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Matrix Biology
Publication date: May 2017
Source:Matrix Biology, Volume 59









Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): Evgenia Karousou, Suniti Misra, Shibnath Ghatak, Katalin Dobra, Martin Götte, Davide Vigetti, Alberto Passi, Nikos K. Karamanos, Spyros S. Skandalis

Synthesis, deposition, and interactions of hyaluronan (HA) with its cellular receptor CD44 are crucial events that regulate the onset and progression of tumors. The intracellular signaling pathways initiated by HA interactions with CD44 leading to tumorigenic responses are complex. Moreover, HA molecules may perform dual functions depending on their concentration and size. Overexpression of variant isoforms of CD44 (CD44v) is most commonly linked to cancer progression, whereas their loss is associated with inhibition of tumor growth. In this review, we highlight that the regulation of HA synthases (HASes) by post-translational modifications, such as O-GlcNAcylation and ubiquitination, environmental factors and the action of microRNAs is important for HA synthesis and secretion in the tumor microenvironment. Moreover, we focus on the roles and interactions of CD44 with various proteins that reside extra- and intracellularly, as well as on cellular membranes with particular reference to the CD44-HA axis in cancer stem cell functions, and the importance of CD44/CD44v6 targeting to inhibit tumorigenesis.





Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): Georgina S. Butler, Andrea R. Connor, Nor Eddine Sounni, Ulrich Eckhard, Charlotte J. Morrison, Agnès Noël, Christopher M. Overall

Members of the CCN family of matricellular proteins are cytokines linking cells to the extracellular matrix. We report that CCN3 (Nov) and CCN5 (WISP2) are novel substrates of MMP14 (membrane-type 1-matrix metalloproteinase, MT1-MMP) that we identified using MMP14 “inactive catalytic domain capture” (ICDC) as a yeast two-hybrid protease substrate trapping platform in parallel with degradomics mass spectrometry screens for MMP14 substrates. CCN3 and CCN5, previously unknown substrates of MMPs, were biochemically validated as substrates of MMP14 and other MMPs in vitro—CCN5 was processed in the variable region by MMP14 and MMP2, as well as by MMP1, 3, 7, 8, 9 and 15. CCN1, 2 and 3 are proangiogenic factors yet we found novel opposing activity of CCN5 that was potently antiangiogenic in an aortic ring vessel outgrowth model. MMP14, a known regulator of angiogenesis, cleaved CCN5 and abrogated the angiostatic activity. CCN3 was also processed in the variable region by MMP14 and MMP2, and by MMP1, 8 and 9. In addition to the previously reported cleavages of CCN1 and CCN2 by several MMPs we found that MMPs 8, 9, and 1 process CCN1, and MMP8 and MMP9 also process CCN2. Thus, our study reveals additional and pervasive family-wide processing of CCN matricellular proteins/cytokines by MMPs. Furthermore, CCN5 cleavage by proangiogenic MMPs results in removal of an angiogenic brake held by CCN5. This highlights the importance of thorough dissection of MMP substrates that is needed to reveal higher-level control mechanisms beyond type IV collagen and other extracellular matrix protein remodelling in angiogenesis. Summary We find CCN family member cleavage by MMPs is more pervasive than previously reported and includes CCN3 (Nov) and CCN5 (WISP2). CCN5 is a novel antiangiogenic factor, whose function is abrogated by proangiogenic MMP cleavage. By processing CCN proteins, MMPs regulate cell responses angiogenesis in connective tissues.





Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): Alexandra K. Pastino, Todd M. Greco, Rommel A. Mathias, Ileana M. Cristea, Jean E. Schwarzbauer

Advanced glycation endproducts (AGEs) are a heterogeneous group of compounds that form via non-enzymatic glycation of proteins throughout our lifespan and at a higher rate in certain chronic diseases such as diabetes. AGEs contribute to the progression of fibrosis, in part by stimulating cellular pathways that affect gene expression. Long-lived ECM proteins are targets for non-enzymatic glycation but the question of whether the AGE-modified ECM leads to excess ECM accumulation and fibrosis remains unanswered. In this study, cellular changes due to AGE accretion in the ECM were investigated. Non-enzymatic glycation of proteins in a decellularized fibroblast ECM was achieved by incubating the ECM in a solution of methylglyoxal (MGO). Mass spectrometry of fibronectin (FN) isolated from the glycated matrix identified twenty-eight previously unidentified MGO-derived AGE modification sites including functional sites such as the RGD integrin-binding sequence. Mesangial cells grown on the glycated, decellularized matrix assembled increased amounts of FN matrix. Soluble AGE-modified bovine serum albumin (BSA) also stimulated FN matrix assembly and this effect was reduced by function-blocking antibodies against the receptor for AGE (RAGE). These results indicate that cells respond to AGEs by increasing matrix assembly and that RAGE is involved in this response. This raises the possibility that the accumulation of ECM during the progression of fibrosis may be enhanced by cell interactions with AGEs on a glycated ECM.





Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): R.S. Ghadiali, S.E. Guimond, J.E. Turnbull, A. Pisconti

Satellite cells (SCs) are skeletal muscle stem cells residing quiescent around healthy muscle fibres. In response to injury or disease SCs activate, proliferate and eventually differentiate and fuse to one another to form new muscle fibres, or to existing damaged fibres to repair them. The sulfated polysaccharide heparan sulfate (HS) is a highly variable biomolecule known to play key roles in the regulation of cell fate decisions, though the changes that muscle HS undergoes during SC differentiation are unknown. Here we show that the sulfation levels of HS increase during SC differentiation; more specifically, we observe an increase in 6-O and 2-O-sulfation in N-acetylated disaccharides. Interestingly, a specific increase in 6-O sulfation is also observed in the heparanome of ageing muscle, which we show leads to promotion of FGF2 signalling and satellite cell proliferation, suggesting a role for the heparanome dynamics in age-associated loss of quiescence. Addition of HS mimetics to differentiating SC cultures results in differential effects: an oversulfated HS mimetic increases differentiation and inhibits FGF2 signalling, a known major promoter of SC proliferation and inhibitor of differentiation. In contrast, FGF2 signalling is promoted by an N-acetylated HS mimetic, which inhibits differentiation and promotes SC expansion. We conclude that the heparanome of SCs is dynamically regulated during muscle differentiation and ageing, and that such changes might account for some of the phenotypes and signalling events that are associated with these processes.





Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): Simone D. Scilabra, Kazuhiro Yamamoto, Martina Pigoni, Kazuma Sakamoto, Stephan A. Müller, Alkmini Papadopoulou, Stefan F. Lichtenthaler, Linda Troeberg, Hideaki Nagase, Kenji Kadomatsu

Tissue inhibitor of metalloproteinases 3 (TIMP-3) is a key regulator of extracellular matrix turnover for its ability to inhibit matrix metalloproteinases (MMPs), adamalysin-like metalloproteinases (ADAMs) and ADAMs with thrombospondin motifs (ADAMTSs). TIMP-3 is a secreted protein whose extracellular levels are regulated by endocytosis via the low-density-lipoprotein receptor-related protein-1 (LRP-1). In this study we developed a molecule able to “trap” TIMP-3 extracellularly, thereby increasing its tissue bioavailability. LRP-1 contains four ligand-binding clusters. In order to investigate the TIMP-3 binding site on LRP-1, we generated soluble minireceptors (sLRPs) containing the four distinct binding clusters or part of each cluster. We used an array of biochemical methods to investigate the binding of TIMP-3 to different sLRPs. We found that TIMP-3 binds to the ligand-binding cluster II of the receptor with the highest affinity and a soluble minireceptor containing the N-terminal half of cluster II specifically blocked TIMP-3 internalization, without affecting the turnover of metalloproteinases. Mass spectrometry-based secretome analysis showed that this minireceptor, named T3TRAP, selectively increased TIMP-3 levels in the extracellular space and inhibited constitutive shedding of a number of cell surface proteins. In conclusion, T3TRAP represents a biological tool that can be used to modulate TIMP-3 levels in the tissue and could be potentially developed as a therapy for diseases characterized by a deficit of TIMP-3, including arthritis.





Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): Samir W. Hamaia, Daisy Luff, Emma J. Hunter, Jean-Daniel Malcor, Dominique Bihan, Donald Gullberg, Richard W. Farndale

The collagen-binding integrins recognise collagen through their inserted (I) domain, where co-ordination of a Mg2+ ion in the metal ion-dependent site is reorganised by ligation by a collagen glutamate residue found in specific collagen hexapeptide motifs. Here we show that GROGER, found in the N-terminal domain of collagens I and III, is only weakly recognised by α10β1, an important collagen receptor on chondrocytes, contrasting with the other collagen-binding integrins. Alignment of I domain sequence and molecular modelling revealed a clash between a unique arginine residue (R215) in α10β1 and the positively-charged GROGER. Replacement of R215 with glutamine restored binding. Substituting arginine at the equivalent locus (Q214) in integrins α1 and α2 I domains impaired their binding to GROGER. Collagen II, abundant in cartilage, lacks GROGER. GRSGET is uniquely expressed in the C-terminus of collagen II, but this motif is similarly not recognised by α10β1. These data suggest an evolutionary imperative to maintain accessibility of the terminal domains of collagen II in tissues such as cartilage, perhaps during endochondral ossification, where α10β1 is the main collagen-binding integrin.





Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): Alfonso Gautieri, Fabian S. Passini, Unai Silván, Manuel Guizar-Sicairos, Giulia Carimati, Piero Volpi, Matteo Moretti, Herbert Schoenhuber, Alberto Redaelli, Martin Berli, Jess G. Snedeker

Concurrent with a progressive loss of regenerative capacity, connective tissue aging is characterized by a progressive accumulation of Advanced Glycation End-products (AGEs). Besides being part of the typical aging process, type II diabetics are particularly affected by AGE accumulation due to abnormally high levels of systemic glucose that increases the glycation rate of long-lived proteins such as collagen. Although AGEs are associated with a wide range of clinical disorders, the mechanisms by which AGEs contribute to connective tissue disease in aging and diabetes are still poorly understood. The present study harnesses advanced multiscale imaging techniques to characterize a widely employed in vitro model of ribose induced collagen aging and further benchmarks these data against experiments on native human tissues from donors of different age. These efforts yield unprecedented insight into the mechanical changes in collagen tissues across hierarchical scales from molecular, to fiber, to tissue-levels. We observed a linear increase in molecular spacing (from 1.45nm to 1.5nm) and a decrease in the D-period length (from 67.5nm to 67.1nm) in aged tissues, both using the ribose model of in vitro glycation and in native human probes. Multiscale mechanical analysis of in vitro glycated tendons strongly suggests that AGEs reduce tissue viscoelasticity by severely limiting fiber–fiber and fibril–fibril sliding. This study lays an important foundation for interpreting the functional and biological effects of AGEs in collagen connective tissues, by exploiting experimental models of AGEs crosslinking and benchmarking them for the first time against endogenous AGEs in native tissue.





Publication date: May 2017
Source:Matrix Biology, Volume 59

Author(s): Ana Tomasovic, Nina Kurrle, Frank Wempe, Silke De-Zolt, Susan Scheibe, Katri Koli, Martin Serchinger, Frank Schnütgen, Duran Sürün, Anja Sterner-Kock, Norbert Weissmann, Harald von Melchner

Latent transforming growth factor beta binding protein 4 (LTBP4) belongs to the fibrillin/LTBP family of proteins and plays an important role as a structural component of extracellular matrix (ECM) and local regulator of TGFβ signaling. We have previously reported that Ltbp4S knock out mice (Ltbp4S−/−) develop centrilobular emphysema reminiscent of late stage COPD, which could be partially rescued by inactivating the antioxidant protein Sestrin 2 (Sesn2). More recent studies showed that Sesn2 knock out mice upregulate Pdgfrβ-controlled alveolar maintenance programs that protect against cigarette smoke induced pulmonary emphysema. Based on this, we hypothesized that the emphysema of Ltbp4S−/− mice is primarily caused by defective Pdgfrβ signaling. Here we show that LTBP4 induces Pdgfrβ signaling by inhibiting the antioxidant Nrf2/Keap1 pathway in a TGFβ-dependent manner. Overall, our data identified Ltbp4 as a major player in lung remodeling and injury repair.





Publication date: May 2017
Source:Matrix Biology, Volume 59









Publication date: May 2017
Source:Matrix Biology, Volume 59









Publication date: Available online 21 April 2017
Source:Matrix Biology

Author(s): Eva Andreuzzi, Roberta Colladel, Rosanna Pellicani, Giulia Tarticchio, Renato Cannizzaro, Paola Spessotto, Benedetta Bussolati, Alessia Brossa, Paolo De Paoli, Vincenzo Canzonieri, Renato V. Iozzo, Alfonso Colombatti, Maurizio Mongiat

Angiogenesis is a crucial process occurring under physiological and pathological conditions, including cancer. The development of blood vessels is tightly regulated by a plethora of cytokines, endothelial cell (EC) receptors and extracellular matrix (ECM) components. In this context, we have shown that Multimerin 2 (MMRN2), an ECM molecule specifically secreted by ECs, exerts angiostatic functions by binding VEGFA and other pro-angiogenic cytokines. Here, we demonstrate that during angiogenic stimuli MMRN2 mRNA levels significantly decrease. Furthermore, we provide evidence that MMRN2 is processed by matrix metalloproteinases (MMPs) including MMP-9 and, to a lesser degree, by MMP-2. This proteolytic cleavage correlates with an increased migration of ECs. Accordingly, MMRN2 down-regulation is associated with an increased number of EC pseudopodia at the migrating front and this effect is attenuated using specific MMP-9 inhibitors. The down-modulation of MMRN2 occurs also in the context of tumor-associated angiogenesis. Immunofluorescence performed on tumor sections indicate a broad co-localization of MMP-9 and MMRN2, suggesting that the molecule may be extensively remodeled during tumor angiogenesis. Given the altered expression in tumors and the key role of MMRN2 in blood vessel function, we postulate that analyses of its expression may serve as a marker to predict the efficacy of the treatments. In conclusion, these data further support the role of MMRN2 as a key molecule regulating EC function and sprouting angiogenesis.





Publication date: Available online 20 April 2017
Source:Matrix Biology

Author(s): Ryuta Tanimoto, Chiara Palladino, Shi-Qiong Xu, Simone Buraschi, Thomas Neill, Leonard G. Gomella, Stephen C. Peiper, Antonino Belfiore, Renato V. Iozzo, Andrea Morrione

Despite extensive clinical and experimental studies over the past decades, the pathogenesis and progression to the castration-resistant stage of prostate cancer remains largely unknown. Progranulin, a secreted growth factor, strongly binds the heparin-sulfate proteoglycan perlecan, and counteracts its biological activity. We established that progranulin acts as an autocrine growth factor and promotes prostate cancer cell motility, invasion, and anchorage-independent growth. Progranulin was overexpressed in prostate cancer tissues vis-à-vis non-neoplastic tissues supporting the hypothesis that progranulin may play a key role in prostate cancer progression. However, progranulin's mode of action is not well understood and proteins regulating progranulin signaling have not been identified. Sortilin, a single-pass type I transmembrane protein of the Vps10 family, binds progranulin in neurons and targets progranulin for lysosomal degradation. Significantly, in DU145 and PC3 cells, we detected very low levels of sortilin associated with high levels of progranulin production and enhanced motility. Restoring sortilin expression decreased progranulin levels, inhibited motility and anchorage-independent growth and destabilized Akt. These results demonstrated a critical role for sortilin in regulating progranulin and suggest that sortilin loss may contribute to prostate cancer progression. Here, we provide the novel observation that progranulin downregulated sortilin protein levels independent of transcription. Progranulin induced sortilin ubiquitination, internalization via clathrin-dependent endocytosis and sorting into early endosomes for lysosomal degradation. Collectively, these results constitute a regulatory feed-back mechanism whereby sortilin downregulation ensures sustained progranulin-mediated oncogenesis.





Publication date: Available online 4 April 2017
Source:Matrix Biology

Author(s): Pia Ringer, Georgina Colo, Reinhard Fässler, Carsten Grashoff

The ability of cells to adhere and sense their mechano-chemical environment is key to many developmental, postnatal homeostatic and pathological processes; however, the underlying molecular mechanisms are still poorly understood. Here, we summarize recent progress that indicates how cell adhesion, mechanotransduction and chemical signaling are coordinated in cells, and we discuss how the combination of novel experimental approaches with theoretical studies is currently utilized to unravel the molecular mechanisms governing mechano-chemical coupling during cell adhesion.





Publication date: Available online 21 February 2017
Source:Matrix Biology

Author(s): Cornelia Tolg, Han Yuan, Sarah M. Flynn, Kaustuv Basu, Jenny Ma, Kenneth Chor Kin Tse, Beatrice Kowalska, Diana Vulkanesku, Mary K. Cowman, James B. McCarthy, Eva A. Turley

Mammary gland morphogenesis begins during fetal development but expansion of the mammary tree occurs postnatally in response to hormones, growth factors and extracellular matrix. Hyaluronan (HA) is an extracellular matrix polysaccharide that has been shown to modulate growth factor-induced branching in culture. Neither the physiological relevance of HA to mammary gland morphogenesis nor the role that HA receptors play in these responses are currently well understood. We show that HA synthase (HAS2) is expressed in both ductal epithelia and stromal cells but HA primarily accumulates in the stroma. HA accumulation and expression of the HA receptors CD44 and RHAMM are highest during gestation when gland remodeling, lateral branch infilling and lobulo-alveoli formation is active. Molecular weight analyses show that approximately 98% of HA at all stages of morphogenesis is >300kDa. Low levels of 7–114kDa HA fragments are also detected and in particular the accumulation of 7–21kDa HA fragments are significantly higher during gestation than other morphogenetic stages (p <0.05). Using these in vivo results as a guide, in culture analyses of mammary epithelial cell lines (EpH4 and NMuMG) were performed to determine the roles of high molecular weight, 7–21kDa (10kDa MWavg) and HA receptors in EGF-induced branching morphogenesis. Results of these assays show that while HA synthesis is required for branching and 10kDa HA fragments strongly stimulate branching, the activity of HA decreases with increasing molecular weight and 500kDa HA strongly inhibits this morphogenetic process. The response to 10kDa HA requires RHAMM function and genetic deletion of RHAMM transiently blunts lateral branching in vivo. Collectively, these results reveal distinct roles for HA polymer size in modulating growth factor induced mammary gland branching and implicates these polymers in both the expansion and sculpting of the mammary tree during gestation.





Publication date: Available online 17 February 2017
Source:Matrix Biology

Author(s): Patricia Paracuellos, Sebastian Kalamajski, Arkadiusz Bonna, Dominique Bihan, Richard W. Farndale, Erhard Hohenester

The small leucine-rich proteoglycans (SLRPs) are important regulators of extracellular matrix assembly and cell signalling. We have determined crystal structures at ~2.2Å resolution of human fibromodulin and chondroadherin, two collagen-binding SLRPs. Their overall fold is similar to that of the prototypical SLRP, decorin, but unlike decorin neither fibromodulin nor chondroadherin forms a stable dimer. A previously identified binding site for integrin α2β1 maps to an α-helix in the C-terminal cap region of chondroadherin. Interrogation of the Collagen Toolkits revealed a unique binding site for chondroadherin in collagen II, and no binding to collagen III. A triple-helical peptide containing the sequence GAOGPSGFQGLOGPOGPO (O is hydroxyproline) forms a stable complex with chondroadherin in solution. In fibrillar collagen I and II, this sequence is aligned with the collagen cross-linking site KGHR, suggesting a role for chondroadherin in cross-linking.





Publication date: Available online 10 February 2017
Source:Matrix Biology

Author(s): Christian Woltersdorf, Melanie Bonk, Birgit Leitinger, Mikko Huhtala, Jarmo Käpylä, Jyrki Heino, Christian Gil Girol, Stephan Niland, Johannes A. Eble, Peter Bruckner, Rita Dreier, Uwe Hansen

Interactions of cells with supramolecular aggregates of the extracellular matrix (ECM) are mediated, in part, by cell surface receptors of the integrin family. These are important molecular components of cell surface-suprastructures regulating cellular activities in general. A subfamily of β1-integrins with von Willebrand-factor A-like domains (I-domains) in their α-chains can bind to collagen molecules and, therefore, are considered as important cellular mechano-receptors. Here we show that chondrocytes strongly bind to cartilage collagens in the form of individual triple helical molecules but very weakly to fibrils formed by the same molecules. We also find that chondrocyte integrins α1β1-, α2β1- and α10β1-integrins and their I-domains have the same characteristics. Nevertheless we find integrin binding to mechanically generated cartilage fibril fragments, which also comprise peripheral non-collagenous material. We conclude that cell adhesion results from binding of integrin-containing adhesion suprastructures to the non-collagenous fibril periphery but not to the collagenous fibril cores. The biological importance of the well-investigated recognition of collagen molecules by integrins is unknown. Possible scenarios may include fibrillogenesis, fibril degradation and/or phagocytosis, recruitment of cells to remodeling sites, or molecular signaling across cytoplasmic membranes. In these circumstances, collagen molecules may lack a fibrillar organization. However, other processes requiring robust biomechanical functions, such as fibril organization in tissues, cell division, adhesion, or migration, do not involve direct integrin-collagen interactions.





Publication date: Available online 24 January 2017
Source:Matrix Biology

Author(s): Liliana Guerra, Teresa Odorisio, Giovanna Zambruno, Daniele Castiglia

Recessive dystrophic epidermolysis bullosa (RDEB) is a skin fragility disease caused by mutations that affect the function and/or the amount of type VII collagen (C7), the major component of anchoring fibrils. Hallmarks of RDEB are unremitting blistering and chronic wounds leading to tissue fibrosis and scarring. Nearly all patients with severe RDEB develop highly metastatic squamous cell carcinomas (SCC) which are the main cause of death. Accumulating evidence from a murine RDEB model and human RDEB cells demonstrates that lack of C7 also directly alters the wound healing process. Non-healing RDEB wounds are characterized by increased inflammation, high transforming growth factor-β1 (TGF-β1) levels and activity, and are heavily populated by myofibroblasts responsible for enhanced fibrogenesis and matrix stiffness. These changes make the RDEB stroma a microenvironment prone to cancer initiation, where cells with features of cancer-associated fibroblasts are found. Here, we discuss recent knowledge on microenvironment alterations in RDEB, highlighting possible therapeutic targets to prevent and/or delay fibrosis and SCC development.





Publication date: Available online 23 January 2017
Source:Matrix Biology

Author(s): Nicole C. Smits, Takashi Kobayashi, Pratyaksh K. Srivastava, Sladjana Skopelja, Julianne A. Ivy, Dustin J. Elwood, Radu V. Stan, Gregory J. Tsongalis, Frank W. Sellke, Peter L. Gross, Michael D. Cole, James T. DeVries, Aaron V. Kaplan, John F. Robb, Scott M. Williams, Nicholas W. Shworak

The HS3ST1 gene controls endothelial cell production of HSAT+ – a form of heparan sulfate containing a specific pentasaccharide motif that binds the anticoagulant protein antithrombin (AT). HSAT+ has long been thought to act as an endogenous anticoagulant; however, coagulation was normal in Hs3st1 / mice that have greatly reduced HSAT+ (HajMohammadi et al., 2003). This finding indicates that HSAT+ is not essential for AT's anticoagulant activity. To determine if HSAT+ is involved in AT's poorly understood inflammomodulatory activities, Hs3st1 / and Hs3st1 +/+ mice were subjected to a model of acute septic shock. Compared with Hs3st1 +/+ mice, Hs3st1 / mice were more susceptible to LPS-induced death due to an increased sensitivity to TNF. For Hs3st1 +/+ mice, AT treatment reduced LPS-lethality, reduced leukocyte firm adhesion to endothelial cells, and dilated isolated coronary arterioles. Conversely, for Hs3st1 / mice, AT induced the opposite effects. Thus, in the context of acute inflammation, HSAT+ selectively mediates AT's anti-inflammatory activity; in the absence of HSAT+, AT's pro-inflammatory effects predominate. To explore if the anti-inflammatory action of HSAT+ also protects against a chronic vascular-inflammatory disease, atherosclerosis, we conducted a human candidate-gene association study on >2000 coronary catheterization patients. Bioinformatic analysis of the HS3ST1 gene identified an intronic SNP, rs16881446, in a putative transcriptional regulatory region. The rs16881446G/G genotype independently associated with the severity of coronary artery disease and atherosclerotic cardiovascular events. In primary endothelial cells, the rs16881446G allele associated with reduced HS3ST1 expression. Together with the mouse data, this leads us to conclude that the HS3ST1 gene is required for AT's anti-inflammatory activity that appears to protect against acute and chronic inflammatory disorders.





Publication date: Available online 19 January 2017
Source:Matrix Biology

Author(s): Lauren A. Griggs, Nadiah T. Hassan, Roshni S. Malik, Brian P. Griffin, Brittany A. Martinez, Lynne W. Elmore, Christopher A. Lemmon

Epithelial-Mesenchymal Transition (EMT) is a dynamic process through which epithelial cells transdifferentiate from an epithelial phenotype into a mesenchymal phenotype. Previous studies have demonstrated that both mechanical signaling and soluble growth factor signaling facilitate this process. One possible point of integration for mechanical and growth factor signaling is the extracellular matrix. Here we investigate the role of the extracellular matrix (ECM) protein fibronectin (FN) in this process. We demonstrate that inhibition of FN fibrillogenesis blocks activation of the Transforming Growth Factor-Beta (TGF-β) signaling pathway via Smad2 signaling, decreases cell migration and ultimately leads to inhibition of EMT. Results show that soluble FN, FN fibrils, or increased contractile forces are insufficient to independently induce EMT. We further demonstrate that inhibition of latent TGF-β1 binding to FN fibrils via either a monoclonal blocking antibody against the growth factor binding domain of FN or through use of a FN deletion mutant that lacks the growth factor binding domains of FN blocks EMT progression, indicating a novel role for FN in EMT in which the assembly of FN fibrils serves to localize TGF-β1 signaling to drive EMT.





Publication date: Available online 4 January 2017
Source:Matrix Biology

Author(s): R.P. Cavalheiro, M.A. Lima, T.R. Jarrouge-Bouças, G.M. Viana, C.C. Lopes, V.J. Coulson-Thomas, J.L. Dreyfuss, E.A. Yates, I.L.S. Tersariol, H.B. Nader

Syndecans are heparan sulfate proteoglycans characterized as transmembrane receptors that act cooperatively with the cell surface and extracellular matrix proteins. Syn4 knockdown was performed in order to address its role in endothelial cells (EC) behavior. Normal EC and shRNA-Syn4-EC cells were studied comparatively using complementary confocal, super-resolution and non-linear microscopic techniques. Confocal and super-resolution microscopy revealed that Syn4 knockdown alters the level and arrangement of essential proteins for focal adhesion, evidenced by the decoupling of vinculin from F-actin filaments. Furthermore, Syn4 knockdown alters the actin network leading to filopodial protrusions connected by VE-cadherin–rich junction. shRNA-Syn4-EC showed reduced adhesion and increased migration. Also, Syn4 silencing alters cell cycle as well as cell proliferation. Moreover, the ability of EC to form tube-like structures in matrigel is reduced when Syn4 is silenced. Together, the results suggest a mechanism in which Syndecan-4 acts as a central mediator that bridges fibronectin, integrin and intracellular components (actin and vinculin) and once silenced, the cytoskeleton protein network is disrupted. Ultimately, the results highlight Syn4 relevance for balanced cell behavior.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Ambra Pozzi, Peter D. Yurchenco, Renato V. Iozzo

Basement membranes are delicate, nanoscale and pliable sheets of extracellular matrices that often act as linings or partitions in organisms. Previously considered as passive scaffolds segregating polarized cells, such as epithelial or endothelial cells, from the underlying mesenchyme, basement membranes have now reached the center stage of biology. They play a multitude of roles from blood filtration to muscle homeostasis, from storing growth factors and cytokines to controlling angiogenesis and tumor growth, from maintaining skin integrity and neuromuscular structure to affecting adipogenesis and fibrosis. Here, we will address developmental, structural and biochemical aspects of basement membranes and discuss some of the pathogenetic mechanisms causing diseases linked to abnormal basement membranes.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Michael J. Randles, Martin J. Humphries, Rachel Lennon

Basement membranes are formed from condensed networks of extracellular matrix (ECM) proteins. These structures underlie all epithelial, mesothelial and endothelial sheets and provide an essential structural scaffold. Candidate-based investigations have established that predominant components of basement membranes are laminins, collagen type IV, nidogens and heparan sulphate proteoglycans. More recently, global proteomic approaches have been applied to investigate ECM and these analyses confirm tissue-specific ECM proteomes with a high degree of complexity. The proteomes consist of structural as well as regulatory ECM proteins such as proteases and growth factors. This review is focused on the proteomic analysis of basement membranes and illustrates how this approach can be used to build our understanding of ECM regulation in health and disease.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Marion Jeanne, Douglas B Gould

COL4A1 and COL4A2 are extracellular matrix proteins that form heterotrimers and are present in nearly all basement membranes in every organ. In the past decade, COL4A1 and COL4A2 mutations have been identified to cause a multi-system disorder for which penetrance and severity of constituent phenotypes can greatly vary. Here, we compare the outcomes of more than 100 mutations identified in patients and data from a murine allelic series to explore the presence of genotype–phenotype correlations – many of which are shared among other types of collagen. We find that there is a frequency bias for COL4A1 over COL4A2 mutations and that glycine (Gly) substitutions within the triple helical domain are the most common class of mutations. Glycine is most often replaced by a charged amino acid, however the position of the mutation, and not the properties of the substituting amino acid, appears to have a greater influence on disease severity. Moreover, the impact of position is not straightforward. Observations from a murine allelic series suggest that mutations in the NC1 domain may result in relatively mild phenotypes via a ‘quantitative’ mechanism similar to other types of collagens, however, this effect was not apparent in human reports. Importantly, other position-dependent effects had differential impacts depending on the phenotype of interest. For example, the severity of cerebrovascular disease correlated with an amino-to-carboxy severity gradient for triple-helical glycine substitutions whereas the penetrance and severity of myopathy and nephropathy appear to involve a functional sub-domain(s). Greater understanding of genotype–phenotype correlations and the interaction of consequences of different mutations will be important for patient prognosis and care and for developing mechanism-based therapeutics to treat individual components of this emerging syndrome.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Dominic Cosgrove, Shiguang Liu

Alport syndrome is the result of mutations in any of three type IV collagen genes, COL4A3, COL4A4, or COL4A5. Because the three collagen chains form heterotrimers, there is an absence of all three proteins in the basement membranes where they are expressed. In the glomerulus, the mature glomerular basement membrane type IV collagen network, normally comprised of two separate networks, α3(IV)/α4(IV)/α5(IV) and α1(IV)/α2(IV), is comprised entirely of collagen α1(IV)/α2. This review addresses the current state of our knowledge regarding the consequence of this change in basement membrane composition, including both the direct, via collagen receptor binding, and indirect, regarding influences on glomerular biomechanics. The state of our current understanding regarding mechanisms of glomerular disease initiation and progression will be examined, as will the current state of the art regarding emergent therapeutic approaches to slow or arrest glomerular disease in Alport patients.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Ritva Heljasvaara, Mari Aikio, Heli Ruotsalainen, Taina Pihlajaniemi

Collagen XVIII is a ubiquitous basement membrane (BM) proteoglycan produced in three tissue-specific isoforms that differ in their N-terminal non-collagenous sequences, but share collagenous and C-terminal non-collagenous domains. The collagenous domain provides flexibility to the large collagen XVIII molecules on account of multiple interruptions in collagenous sequences. Each isoform has a complex multi-domain structure that endows it with an ability to perform various biological functions. The long isoform contains a frizzled-like (Fz) domain with Wnt-inhibiting activity and a unique domain of unknown function (DUF959), which is also present in the medium isoform. All three isoforms share an N-terminal laminin-G-like/thrombospondin-1 sequence whose specific functions still remain unconfirmed. The proteoglycan nature of the isoforms further increases the functional diversity of collagen XVIII. An anti-angiogenic domain termed endostatin resides in the C-terminus of collagen XVIII and is proteolytically cleaved from the parental molecule during the BM breakdown for example in the process of tumour progression. Recombinant endostatin can efficiently reduce tumour angiogenesis and growth in experimental models by inhibiting endothelial cell migration and proliferation or by inducing their death, but its efficacy against human cancers is still a subject of debate. Mutations in the COL18A1 gene result in Knobloch syndrome, a genetic disorder characterised mainly by severe eye defects and encephalocele and, occasionally, other symptoms. Studies with gene-modified mice have elucidated some aspects of this rare disease, highlighting in particular the importance of collagen XVIII in the development of the eye. Research with model organisms have also helped in determining other structural and biological functions of collagen XVIII, such as its requirement in the maintenance of BM integrity and its emerging roles in regulating cell survival, stem or progenitor cell maintenance and differentiation and inflammation. In this review, we summarise current knowledge on the properties and endogenous functions of collagen XVIII in normal situations and tissue dysregulation. When data is available, we discuss the functions of the distinct isoforms and their specific domains.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Jouni Uitto, Cristina Has, Hassan Vahidnezhad, Leila Youssefian, Leena Bruckner-Tuderman

Epidermolysis bullosa (EB), a phenotypically heterogeneous group of skin fragility disorders, is characterized by blistering and erosions with considerable morbidity and mortality. Mutations in as many as 18 distinct genes expressed at the cutaneous basement membrane zone have been shown to be associated with the blistering phenotype, attesting to the role of the corresponding proteins in providing stable association of the epidermis to the dermis through adhesion at the dermo-epidermal basement membrane zone. Thus, different forms of EB have been highly instructive in providing information on the physiological functions of these proteins as integral components of the supramolecular adhesion complexes. In addition, precise information of the underlying genes and distinct mutations in families with EB has been helpful in subclassification of the disease with prognostic implications, as well as for prenatal testing and preimplantation genetic diagnosis. Furthermore, knowledge of the types of mutations is a prerequisite for application of allele-specific treatment approaches that have been recently developed, including read-through of premature termination codon mutations and chaperone-facilitated intracellular transport of conformationally altered proteins to proper physiologic subcellular location. Collectively, EB serves as a paradigm of heritable skin diseases in which significant progress has been made in identifying the underlying genetic bases and associated aberrant pathways leading from mutations to the phenotype, thus allowing application of precision medicine for this, currently intractable group of diseases.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Robert S. Rogers, Hiroshi Nishimune

The synapse between motor neurons and skeletal muscle is known as the neuromuscular junction (NMJ). Proper alignment of presynaptic and post-synaptic structures of motor neurons and muscle fibers, respectively, is essential for efficient motor control of skeletal muscles. The synaptic cleft between these two cells is filled with basal lamina. Laminins are heterotrimer extracellular matrix molecules that are key members of the basal lamina. Laminin α4, α5, and β2 chains specifically localize to NMJs, and these laminin isoforms play a critical role in maintenance of NMJs and organization of synaptic vesicle release sites known as active zones. These individual laminin chains exert their role in organizing NMJs by binding to their receptors including integrins, dystroglycan, and voltage-gated calcium channels (VGCCs). Disruption of these laminins or the laminin-receptor interaction occurs in neuromuscular diseases including Pierson syndrome and Lambert–Eaton myasthenic syndrome (LEMS). Interventions to maintain proper level of laminins and their receptor interactions may be insightful in treating neuromuscular diseases and aging related degeneration of NMJs.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Raphael Vezina-Audette, Mathieu Tremblay, Salvatore Carbonetto

Previous work has shown that myotubes cultured on laminin-coated substrates form complex aggregates of synaptic proteins that are similar in shape and composition to neuromuscular junctions (NMJs). Here we show that laminin instructs the location of complex aggregates which form only on the lower surface when laminin is coated onto culture dishes but over the entire cell when laminin is added in solution. Silencing of myotubes by agents that block electrical activity (tetrodotoxin, verapamil) or by inhibitors of calmodulin dependent kinase (CaMKII) render the myotube permissive for the formation of complex aggregates. Treatment with laminin alone will facilitate the formation of complex aggregates hours later when myotubes are made permissive by inhibiting CaMKII. The AChR agonist carbachol disperses pre formed aggregates suggesting that non-permissiveness may involve active dispersal of AChRs. The permissive period requires ongoing protein synthesis. The latter may reflect a requirement for rapsyn, which turns over rapidly, and is necessary for aggregation. Consistent with this geldanamycin, an agent that increases rapsyn turnover disrupts complex aggregates. Agrin is well known to induce small clusters of AChRs but does not induce complex aggregates even though aggregate formation requires MuSK, a receptor tyrosine kinase activated by agrin. Dystroglycan (DG) is the major laminin receptor mediating complex aggregate formation with some contribution from β1 integrins. In addition, there is a pool of CaMKII associated with DG. We discuss how these permissive and instructive mechanisms bear on NMJ formation in vivo.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Alexander Nyström, Olivier Bornert, Tobias Kühl

For most disorders caused by mutations in genes encoding basement membrane (BM) proteins, there are at present only limited treatment options available. Genetic BM-linked disorders can be viewed as especially suited for treatment with cell-based therapy approaches because the proteins that need to be restored are located in the extracellular space. In consequence, complete and permanent engraftment of cells does not necessarily have to occur to achieve substantial causal therapeutic effects. For these disorders cells can be used as transient vehicles for protein replacement. In addition, it is becoming evident that BM-linked genetic disorders are modified by secondary diseases mechanisms. Cell-based therapies have also the ability to target such disease modifying mechanisms. Thus, cell therapies can simultaneously provide causal treatment and symptomatic relief, and accordingly hold great potential for treatment of BM-linked disorders. However, this potential has for most applications and diseases so far not been realized. Here, we will present the state of cell therapies for BM-linked diseases. We will discuss use of both pluripotent and differentiated cells, the limitation of the approaches, their challenges, and the way forward to potential wider implementation of cell therapies in the clinics.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Jacopo Di Russo, Melanie-Jane Hannocks, Anna-Liisa Luik, Jian Song, Xueli Zhang, Lema Yousif, Gunita Aspite, Rupert Hallmann, Lydia Sorokin







Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Mary H. Foster

Basement membrane components are targets of autoimmune attack in diverse diseases that destroy kidneys, lungs, skin, mucous membranes, joints, and other organs in man. Epitopes on collagen and laminin, in particular, are targeted by autoantibodies and T cells in anti-glomerular basement membrane glomerulonephritis, Goodpasture's disease, rheumatoid arthritis, post-lung transplant bronchiolitis obliterans syndrome, and multiple autoimmune dermatoses. This review examines major diseases linked to basement membrane autoreactivity, with a focus on investigations in patients and animal models that advance our understanding of disease pathogenesis. Autoimmunity to glomerular basement membrane type IV is discussed in depth as a prototypic organ-specific autoimmune disease yielding novel insights into the complexity of anti-basement membrane immunity and the roles of genetic and environmental susceptibility.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Jean-Baptiste Oudart, Jean-Claude Monboisse, François-Xavier Maquart, Bertrand Brassart, Sylvie Brassart-Pasco, Laurent Ramont

Type XIX collagen is a minor collagen that is associated with the basement membrane zone that belongs to the FACIT family (Fibril-Associated Collagens with Interrupted Triple helices). The FACIT family is composed of type IX, XII, XIV, XVI, XX, XXI, XXII and XIX collagens, which share many highly conserved structural motifs: a short NC1 domain, a thrombospondin-like N-terminal domain (TSPN), and numerous cysteine residues. The main role of FACITs is to ensure the integrity and stability of the extracellular matrix and its fibrillar collagen network by regulating the formation and size of the collagen fibrils. Type XIX collagen was discovered in a human rhabdomyosarcoma cell line. The collagen α1(XIX) chain is composed of 5 triple-helical domains (COL) interrupted by 6 non-triple-helical (NC) domains with a short, C-terminal, 19 amino acid non-collagenous domain (NC1). This collagen is involved in the differentiation of muscle cells, central nervous system development, and formation of the esophagus. Type XIX collagen is associated with the basement membrane zone, like type XVIII and XV collagens. Its short NC1(XIX) C-terminal domain inhibits the migration and invasion of melanoma cells. It also exerts a strong anti-angiogenic effect by inhibiting MMP-14 and VEGF expression. NC1(XIX) binding to αvβ3 integrin decreases the phosphorylation of proteins involved in the FAK (Focal Adhesion Kinase)/PI3K (PhosphoInositide 3-Kinase)/Akt (protein kinase B)/mTOR (Mammalian Target Of Rapamycin) pathway. On the other hand, NC1(XIX) induces an increase in GSK3β activity by decreasing its level of phosphorylation. The inhibition of this pathway could explain the anti-tumor properties of the NC1(XIX) domain.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Tammy T. Chang, Dhruv Thakar, Valerie M. Weaver

Clinically, non-invasive carcinomas are confined to the epithelial side of the basement membrane and are classified as benign, whereas invasive cancers invade through the basement membrane and thereby acquire the potential to metastasize. Recent findings suggest that, in addition to protease-mediated degradation and chemotaxis-stimulated migration, basement membrane invasion by malignant cells is significantly influenced by the stiffness of the associated interstitial extracellular matrix and the contractility of the tumor cells that is dictated in part by their oncogenic genotype. In this review, we highlight recent findings that illustrate unifying molecular mechanisms whereby these physical cues contribute to tissue fibrosis and malignancy in three epithelial organs: breast, pancreas, and liver. We also discuss the clinical implications of these findings and the biological properties and clinical challenges linked to the unique biology of each of these organs.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Sanela Mrkonjic, Olivier Destaing, Corinne Albiges-Rizo

Degradation of the extracellular matrix is a critical step of tumor cell invasion. Both protease-dependent and -independent mechanisms have been described as alternate processes in cancer cell motility. Interestingly, some effectors of protease-dependent degradation are focalized at invadosomes and are directly coupled with contractile and adhesive machineries composed of multiple mechanosensitive proteins. This review presents recent findings in protease-dependent mechanisms elucidating the ways the force affects extracellular matrix degradation by targeting protease expression and activity at invadosome. The aim is to highlight mechanosensing and mechanotransduction processes to direct the degradative activity at invadosomes, with the focus on membrane tension, proteases and mechanosensitive ion channels.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): David Pulido, David C. Briggs, Jinwen Hua, Erhard Hohenester

Laminins are a major constituent of all basement membranes. The polymerisation of laminins at the cell surface is mediated by the three short arms of the cross-shaped laminin heterotrimer. The short arms contain repeats of laminin-type epidermal growth factor-like (LE) domains, interspersed with globular domains of unknown function. A single LF domain is inserted between LE5 and LE6 of the laminin β1 and β2 chains. We report the crystal structure at 1.85Å resolution of the laminin β2 LE5-LF-LE6 region. The LF domain consists of a β-sandwich related to bacterial family 35 carbohydrate binding modules, and more distantly to the L4 domains present in the short arms of laminin α and γ chains. An α-helical region mediates the extensive interaction of the LF domain with LE5. The relative arrangement of LE5 and LE6 is very similar to that of consecutive LE domains in uninterrupted LE tandems. Fitting atomic models to a low-resolution structure of the first eight domains of the laminin β1 chain determined by small-angle X-ray scattering suggests a deviation from the regular LE array at the LE4–LE5 junction. These results advance our understanding of laminin structure.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Veronika Ramovs, Lisa te Molder, Arnoud Sonnenberg

Integrins play an important role in cell adhesion by linking the cytoskeleton of cells to components in the extracellular matrix. In this capacity, integrins cooperate with different cell surface receptors, including growth factor receptors and G-protein coupled receptors, to regulate intracellular signaling pathways that control cell polarization, spreading, migration, survival, and gene expression. A distinct subfamily of molecules in the integrin family of adhesion receptors is formed by receptors that mediate cell adhesion to laminins, major components of the basement membrane that lie under clusters of cells or surround them, separating them from other cells and/or adjacent connective tissue. During the past decades, many studies have provided evidence for a role of laminin-binding integrins in tumorigenesis, and both tumor-promoting and suppressive activities have been identified. In this review we discuss the dual role of the laminin-binding integrins α3β1 and α6β4 in tumor development and progression, and examine the factors and mechanisms involved in these opposing effects.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Olga M. Viquez, Eugenia M. Yazlovitskaya, Tianxiang Tu, Glenda Mernaugh, Pablo Secades, Karen K. McKee, Elizabeth Georges-Labouesse, Adele De Arcangelis, Vito Quaranta, Peter Yurchenco, Leslie C. Gewin, Arnoud Sonnenberg, Ambra Pozzi, Roy Zent

Laminins are a major constituent of the basement membranes of the kidney collecting system. Integrins, transmembrane receptors formed by non-covalently bound α and β subunits, serve as laminin receptors, but their role in development and homeostasis of the kidney collecting system is poorly defined. Integrin α3β1, one of the major laminin receptors, plays a minor role in kidney collecting system development, while the role of α6 containing integrins (α6β1 and α6β4), the other major laminin receptors, is unknown. Patients with mutations in α6 containing integrins not only develop epidermolysis bullosa, but also have abnormalities in the kidney collecting system. In this study, we show that selectively deleting the α6 or β4 integrin subunits at the initiation of ureteric bud development in mice does not affect morphogenesis. However, the collecting system becomes dilated and dysmorphic as the mice age. The collecting system in both null genotypes was also highly susceptible to unilateral ureteric obstruction injury with evidence of excessive tubule dilatation and epithelial cell apoptosis. Mechanistically, integrin α6-null collecting duct cells are unable to withstand high mechanical force when adhered to laminin. Thus, we conclude that α6 integrins are important for maintaining the integrity of the kidney collecting system by enhancing tight adhesion of the epithelial cells to the basement membrane. These data give a mechanistic explanation for the association between kidney collecting system abnormalities in patients and epidermolysis bullosa.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Corina M. Borza, Yan Su, Truc-Linh Tran, Ling Yu, Nick Steyns, Kayla J. Temple, Marcin J. Skwark, Jens Meiler, Craig W. Lindsley, Brennan R. Hicks, Birgit Leitinger, Roy Zent, Ambra Pozzi

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that binds to and is activated by collagens. DDR1 expression increases following kidney injury and accumulating evidence suggests that it contributes to the progression of injury. To this end, deletion of DDR1 is beneficial in ameliorating kidney injury induced by angiotensin infusion, unilateral ureteral obstruction, or nephrotoxic nephritis. Most of the beneficial effects observed in the DDR1-null mice are attributed to reduced inflammatory cell infiltration to the site of injury, suggesting that DDR1 plays a pro-inflammatory effect. The goal of this study was to determine whether, in addition to its pro-inflammatory effect, DDR1 plays a deleterious effect in kidney injury by directly regulating extracellular matrix production. We show that DDR1-null mice have reduced deposition of glomerular collagens I and IV as well as decreased proteinuria following the partial renal ablation model of kidney injury. Using mesangial cells isolated from DDR1-null mice, we show that these cells produce significantly less collagen compared to DDR1-null cells reconstituted with wild type DDR1. Moreover, mutagenesis analysis revealed that mutations in the collagen binding site or in the kinase domain significantly reduce DDR1-mediated collagen production. Finally, we provide evidence that blocking DDR1 kinase activity with an ATP-competitive small molecule inhibitor reduces collagen production. In conclusion, our studies indicate that the kinase activity of DDR1 plays a key role in DDR1-induced collagen synthesis and suggest that blocking collagen-mediated DDR1 activation may be beneficial in fibrotic diseases.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Shaohua Li, Yanmei Qi, Karen McKee, Jie Liu, June Hsu, Peter D. Yurchenco

During early embryogenesis, endodermal γ1-laminin expression is required for basement membrane (BM) assembly, promoting conversion of non-polar pluripotent cells into polarized epiblast. The influence of laminin-111 (Lm111) and its integrin and dystroglycan (DG) receptors on epiblast in embryoid bodies (EBs), a model for differentiation of the embryonic plate, was further investigated. Lm111 added to the medium of EBs initiated conversion of inner nonpolar cell to the polarized epiblast epithelium with an exterior-to-central basal-to-apical orientation. Microinjection of Lm111 into EB interiors resulted in an interior BM with complete inversion of cell polarity. Lm111 assembled a BM on integrin-β1 null EBs with induction of polarization at reduced efficiency. β-Integrin compensation was not detected in these nulls with integrin adaptor proteins failing to assemble. A dimer of laminin LG domains 4–5 (LZE3) engineered to strongly bind to α-dystroglycan almost completely inhibited laminin accumulation on integrin β1-null EBs, reducing BM and ablating cell polarization. When Lm111 was incubated with integrin-β1/dystroglycan double-knockout EBs, laminin failed to accumulate on the EBs, the EBs did not differentiate, and the EBs underwent apoptosis. Collectively the findings support the hypotheses that the locus of laminin cell surface assembly can determine the axis of epithelial polarity. This requires integrin- and/or dystroglycan-dependent binding to laminin LG domains with the highest efficiency achieved when both receptors are present. Finally, EBs that cannot assemble a matrix undergo apoptosis.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Maria A. Gubbiotti, Thomas Neill, Renato V. Iozzo

Perlecan, a large basement membrane heparan sulfate proteoglycan, is expressed in a wide array of tissues where it regulates diverse cellular processes including bone formation, inflammation, cardiac development, and angiogenesis. Here we provide a contemporary review germane to the biology of perlecan encompassing its genetic regulation as well as an analysis of its modular protein structure as it pertains to function. As perlecan signaling from the extracellular matrix converges on master regulators of autophagy, including AMPK and mTOR, via a specific interaction with vascular endothelial growth factor receptor 2, we specifically focus on the mechanism of action of perlecan in autophagy and angiogenesis and contrast the role of endorepellin, the C-terminal fragment of perlecan, in these cellular and morphogenic events.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Dorin-Bogdan Borza

The glomerular basement membrane (GBM) is an essential component of the glomerular filtration barrier. Heparan sulfate proteoglycans such as agrin are major components of the GBM, along with α345(IV) collagen, laminin-521 and nidogen. A loss of GBM heparan sulfate chains is associated with proteinuria in several glomerular diseases and may contribute to the underlying pathology. As the major determinants of the anionic charge of the GBM, heparan sulfate chains have been thought to impart charge selectivity to the glomerular filtration, a view challenged by the negligible albuminuria in mice that lack heparan sulfate in the GBM. Recent studies provide increasing evidence that heparan sulfate chains modulate local complement activation by recruiting complement regulatory protein factor H, the major inhibitor of the alternative pathway in plasma. Factor H selectively inactivates C3b bound to surfaces bearing host-specific polyanions such as heparan sulfate, thus limiting complement activation on self surfaces such as the GBM, which are not protected by cell-bound complement regulators. We discuss mechanisms whereby the acquired loss of GBM heparan sulfate can impair the local regulation of the alternative pathway, exacerbating complement activation and glomerular injury in immune-mediated kidney diseases such as membranous nephropathy and lupus nephritis.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Vaishali N. Patel, Dallas L. Pineda, Matthew P. Hoffman

Branching morphogenesis is a fundamental process in the development of diverse epithelial organs such as the lung, kidney, liver, pancreas, prostate, salivary, lacrimal and mammary glands. A unifying theme during organogenesis is the importance of epithelial cell interactions with the extracellular matrix (ECM) and growth factors (GFs). The diverse developmental mechanisms giving rise to these epithelial organs involve many organ-specific GFs, but a unifying paradigm during organogenesis is the regulation of GF activity by heparan sulfates (HS) on the cell surface and in the ECM. This primarily involves the interactions of GFs with the sulfated side-chains of HS proteoglycans. HS is one of the most diverse biopolymers and modulates GF binding and signaling at the cell surface and in the ECM of all tissues. Here, we review what is known about how HS regulates branching morphogenesis of epithelial organs with emphasis on the developing salivary gland, which is a classic model to investigate epithelial-ECM interactions. We also address the structure, biosynthesis, turnover and function of HS during organogenesis. Understanding the regulatory mechanisms that control HS dynamics may aid in the development of therapeutic interventions for diseases and novel strategies for tissue engineering and regenerative medicine.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Ricardo Cruz-Acuña, Andrés J. García

Naturally-derived materials have been extensively used as 3D cellular matrices as their inherent bioactivity makes them suitable for the study of many cellular processes. Nevertheless, lot-to-lot variability, inability to decouple biochemical and biophysical properties and, in some types, their tumor-derived nature limits their translational potential and reliability. One innovative approach to overcome these limitations has focused on incorporating bioactivity into cytocompatible, synthetic hydrogels that present tunable physicochemical properties. This review provides an overview of successful approaches to convey basement membrane-like bioactivity into 3D artificial hydrogel matrices in order to recapitulate cellular responses to native matrices. Recent advances involving biofunctionalization of synthetic hydrogels via incorporation of bioactive motifs that promote cell-matrix interactions and cell-directed matrix degradation will be discussed. This review highlights how the tunable physicochemical properties of biofunctionalized synthetic hydrogel matrices can be exploited to study the separate contributions of biochemical and biophysical matrix properties to different cellular processes.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Astgik Petrosyan, Stefano Da Sacco, Nikita Tripuraneni, Ursula Kreuser, Maria Lavarreda-Pearce, Riccardo Tamburrini, Roger E. De Filippo, Giuseppe Orlando, Paolo Cravedi, Laura Perin

The outcome of tissue engineered organ transplants depends on the capacity of the biomaterial to promote a pro-healing response once implanted in vivo. Multiple studies, including ours, have demonstrated the possibility of using the extracellular matrix (ECM) of animal organs as platform for tissue engineering and more recently, discarded human organs have also been proposed as scaffold source. In contrast to artificial biomaterials, natural ECM has the advantage of undergoing continuous remodeling which allows adaptation to diverse conditions. It is known that natural matrices present diverse immune properties when compared to artificial biomaterials. However, how these properties compare between diseased and healthy ECM and artificial scaffolds has not yet been defined. To answer this question, we used decellularized renal ECM derived from WT mice and from mice affected by Alport Syndrome at different time-points of disease progression as a model of renal failure with extensive fibrosis. We characterized the morphology and composition of these ECMs and compared their in vitro effects on macrophage activation with that of synthetic scaffolds commonly used in the clinic (collagen type I and poly-L-(lactic) acid, PLLA). We showed that ECM derived from Alport kidneys differed in fibrous protein deposition and cytokine content when compared to ECM derived from WT kidneys. Yet, both WT and Alport renal ECM induced macrophage differentiation mainly towards a reparative (M2) phenotype, while artificial biomaterials towards an inflammatory (M1) phenotype. Anti-inflammatory properties of natural ECMs were lost when homogenized, hence three-dimensional structure of ECM seems crucial for generating an anti-inflammatory response. Together, these data support the notion that natural ECM, even if derived from diseased kidneys promote a M2 protolerogenic macrophage polarization, thus providing novel insights on the applicability of ECM obtained from discarded organs as ideal scaffold for tissue engineering.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): Celestial R. Jones-Paris, Sayan Paria, Taloa Berg, Juan Saus, Gautam Bhave, Bibhash C. Paria, Billy G. Hudson

Basement membranes (BMs) are specialized extracellular scaffolds that influence behaviors of cells in epithelial, endothelial, muscle, nervous, and fat tissues. Throughout development and in response to injury or disease, BMs are fine-tuned with specific protein compositions, ultrastructure, and localization. These features are modulated through implements of the BM toolkit that is comprised of collagen IV, laminin, perlecan, and nidogen. Two additional proteins, peroxidasin and Goodpasture antigen-binding protein (GPBP), have recently emerged as potential members of the toolkit. In the present study, we sought to determine whether peroxidasin and GPBP undergo dynamic regulation in the assembly of uterine tissue BMs in early pregnancy as a tractable model for dynamic adult BMs. We explored these proteins in the context of collagen IV and laminin that are known to extensively change for decidualization. Electron microscopic analyses revealed: 1) a smooth continuous layer of BM in between the epithelial and stromal layers of the preimplantation endometrium; and 2) interrupted, uneven, and progressively thickened BM within the pericellular space of the postimplantation decidua. Quantification of mRNA levels by qPCR showed changes in expression levels that were complemented by immunofluorescence localization of peroxidasin, GPBP, collagen IV, and laminin. Novel BM-associated and subcellular spatiotemporal localization patterns of the four components suggest both collective pericellular functions and distinct functions in the uterus during reprogramming for embryo implantation.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58

Author(s): R. Tyler Miller

Physical properties are differentiated characteristics of tissues that are essential to their function. For example, the function of bone depends on its rigidity, and the function of skin depends on its elasticity. The aggregate physical properties of tissues are determined by a collaborative relationship between their cells and matrix and are the product of genetic programs, circulating chemical signals, physical signals, and age. The mechanical properties of matrix and basement membranes in biologic systems are difficult to understand in detail because of their complexity and technical limitations of measurements. Matrix may contain fibrillary collagens, network collagens, other fibrillar proteins such as elastin, fibronectin, and laminins, proteoglycans, and can be a reservoir for growth factors. In each tissue and in different regions of the same tissue, matrix composition can vary. The goal of measuring the mechanical properties of matrix is to understand the physical environment experienced by specific cell types to be able to control cell behavior in vivo and for tissue engineering. At this time, such precise analysis is not possible. The general elastic properties of tissues are now better characterized, and model systems using limited numbers of matrix constituents permit improved understanding of the physical behavior of matrix and its effects on cells. This review will describe model systems for understanding problems of matrix elasticity, focus on a relatively new aspect of matrix mechanics, strain-stiffening, and the interactions of cells with matrix to produce overall tissue mechanical properties.





Publication date: January 2017
Source:Matrix Biology, Volumes 57–58









Publication date: Available online 30 December 2016
Source:Matrix Biology

Author(s): Ville Koistinen, Kai Härkönen, Riikka Kärnä, Uma Thanigai Arasu, Sanna Oikari, Kirsi Rilla

The mesothelium is a membrane that forms the lining of several body cavities. It is composed of simple squamous mesothelial cells that secrete a glycosaminoglycan-rich lubricating fluid between inner organs. One of the most abundant glycosaminoglycans of those fluids is hyaluronan, which is synthesized on a plasma membrane and especially on apical filopodia of cultured cells. Our recent study showed that similar hyaluronan-rich protrusions are found in mesothelial lining in vivo, which suggests that hyaluronan synthesis in plasma membrane protrusions is a general process. However, the mesothelial lining was negative for the hyaluronan receptor CD44 while in many previous studies cultured mesothelial cells have been shown to express CD44. To further explore these findings we induced epithelial to mesenchymal transition in primary rat mesothelial cells by EGF-treatment and scratch wounding. Surprisingly, the results showed that at a normal epithelial, confluent stage the mesothelial cells are negative for CD44, but EMT induced by EGF or wounding activates CD44 expression and the whole hyaluronan synthesis machinery. In addition to typical EMT-like morphological changes, the growth of apical filopodia and budding of extracellular vesicles (EVs) were induced. In summary, the results of this study show that the activation of hyaluronan synthesis machinery, especially the expression of CD44 is strongly associated with EMT induced by EGF and wounding in mesothelial cells. Moreover, EMT enhances the secretion of EVs that carry CD44 and hyaluronan, which may be important regulators in EV interactions with their targets and ECM remodeling. The results of the present study also suggest that CD44 is a potential marker for EVs, especially those secreted from cells during tissue repair and pathological processes.





Publication date: Available online 20 December 2016
Source:Matrix Biology

Author(s): Kai Hu, Bjorn R. Olsen, Tatiana Y. Besschetnova

Our previous studies of Antxr1 knockout mice suggested that fibrotic skin abnormalities in these mice are associated with increased VEGF signaling. Here, based on studies of primary fibroblasts isolated from skin of Antx1 +/+ and Antxr1 −/− mice at embryonic stage E17.5 and postnatal day P49, we conclude that increased Col1a1 and Fn1 expression in Antxr1-deficient fibroblasts is partly mediated by a cell-autonomous ANTXR1-dependent mechanism. In turn, this may act in parallel with VEGF-dependent regulation of collagen type I and fibronectin production. We demonstrate that shRNA mediated knockdown of VEGF in Antxr1 −/− fibroblasts reduces Col1a1 and Fn1 expression to below control levels, and these are restored by exogenous addition of recombinant VEGF. In addition, the increase in protein levels of collagen type I and fibronectin in mutant cells is blocked by VEGF neutralizing antibody. However, expressing the longest isoform of ANTXR1 (sv1) in mutant fibroblasts decreases levels of Ctgf, Col1a1 and Fn1 transcripts, but has no effect on VEGF expression. Taken together, our data suggest that the increased matrix production in Antxr1- deficient fibroblasts primarily occurs via a CTGF-dependent pathway and that other ANTXR1–associated mechanisms contribute to VEGF-dependent increase of collagen type I and fibronectin expression. Our findings provide a basis for further studies of novel ANTXR1-dependent connective tissue homeostatic control mechanisms in healthy individuals, patients with organ fibrosis, and patients with GAPO syndrome.





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