Regulation of Matrix Assembly through Rigidity-dependent Fibronectin Conformational Changes

Carraher, Cara Lea; Schwarzbauer, Jean E.

doi:10.1074/jbc.m112.435271

Cited by 46 publications

(48 citation statements)

References 66 publications

(72 reference statements)

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“…AGE-induced cross-linking has been shown to increase the stiffness of collagen [53], and chemically crosslinking FN matrix stabilizes it and reduces fibril breakage by shear forces [54]. Increased tissue stiffness also increased FN matrix assembly [55]. Therefore, AGE-induced crosslinking of FN within the matrix might be another mechanism to promote matrix accumulation.…”

Section: Discussionmentioning

confidence: 99%

Stimulatory effects of advanced glycation endproducts (AGEs) on fibronectin matrix assembly

et al. 2017

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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.

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Section: Discussionmentioning

confidence: 99%

Stimulatory effects of advanced glycation endproducts (AGEs) on fibronectin matrix assembly

et al. 2017

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“…Because increased tissue stiffness is a hallmark of most solid tumor progression and has been shown to affect fibronectin assembly and deposition (28,29), we assessed whether tissue stiffness was affecting the expression of the EDB-FN splice variant within PyMT tumors. To that end, we decreased tumor tissue stiffness by preventing ECM cross-linking by treating the mice with the lysyl oxidase inhibitor β-aminopropionitrile (BAPN) ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Tissue stiffness regulates serine/arginine-rich protein-mediated splicing of the extra domain B-fibronectin isoform in tumors

Bordeleau

Califano

Abril

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Alternative splicing of proteins gives rise to different isoforms that play a crucial role in regulating several cellular processes. Notably, splicing profiles are altered in several cancer types, and these profiles are believed to be involved in driving the oncogenic process. Although the importance of alternative splicing alterations occurring during cancer is increasingly appreciated, the underlying regulatory mechanisms remain poorly understood. In this study, we use both biochemical and physical tools coupled with engineered models, patient samples, and a murine model to investigate the role of the mechanical properties of the tumor microenvironment in regulating the production of the extra domain-B (EDB) splice variant of fibronectin (FN), a hallmark of tumor angiogenesis. Specifically, we show that the amount of EDB-FN produced by endothelial cells increases with matrix stiffness both in vitro and within mouse mammary tumors. Matrix stiffness regulates splicing through the activation of serine/arginine rich (SR) proteins, the splicing factors involved in the production of FN isoforms. Activation of the SR proteins by matrix stiffness and the subsequent production of EDB-FN are dependent on intracellular contractility and PI3K-AKT signaling. Notably, matrix stiffness-mediated splicing is not limited to EDB-FN, but also affects splicing in the production of PKC βII and the VEGF 165b splice variant. Together, these results demonstrate that the mechanical properties of the microenvironment regulate alternative splicing and establish a previously unidentified mechanism by which cells can adapt to their microenvironment.alternative splicing | extracellular matrix | matrix stiffness | angiogenesis | cancer progression D ifferential expression of protein isoforms through alternative splicing is a key element to generating protein diversity and can result in widely different cell phenotypes and behaviors (1-3). Interestingly, tumors exhibit several major differences in protein isoform expression patterns compared with healthy tissue (2, 4), and some of these changes are thought to favor oncogenesis (1). Notably, splicing events are regulated at the pre-mRNA level by splicing regulatory factors that include a family of serine/arginine rich (SR) proteins (5). Elevated SR protein levels have been associated with cancer (5); however, the physiological cues that drive splicing are not well defined.Among the various alternatively spliced proteins present in tumors, the splice variant of fibronectin (FN) that includes the extra domain-B (EDB) type III repeat has been of particular interest in the cancer community because inclusion of the EDB fragment has been proposed as a way to identify and target tumor vasculature (6). EDB-FN is produced by endothelial cells (ECs) in tumors and may favor angiogenesis (7-9). Splicing of FN is regulated by several SR proteins, including SRp40 and SRp20, in several different cell types (10-12). Although the presence of EDB-FN is fairly unique to tumor vasculature, the mechanisms governin...

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“…Fibroblasts cultured in free-floating collagen gels generate less stress and lack fibronectin-containing fibrils. More recently, Carraher and Schwarzbauer [50] utilized a polyacrylamide model to evaluate the role of matrix stiffness on fibronectin organization. Polyacrylamide scaffolds have become popular three-dimensional models as their rigidity can be modulated by altering the ratios of the components contributing to polymerization of the scaffold.…”

Section: Effects Of Tissue Stiffness On Fibrosismentioning

confidence: 99%

“…This is consistent with other studies illustrating that multiple proteins that are involved in mechanotransduction become extended in response to mechanical force thus revealing cryptic interaction sites that mediate activity of the proteins. Indeed, providing exogenous unfolded fibronectin to cells in “soft” polyacrylamide gels increases FAK activation to a similar degree as culture in more rigid gels [50]. …”

Section: Effects Of Tissue Stiffness On Fibrosismentioning

confidence: 99%

Regulation of Tissue Fibrosis by the Biomechanical Environment

Carver

Goldsmith

2013

BioMed Research International

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The biomechanical environment plays a fundamental role in embryonic development, tissue maintenance, and pathogenesis. Mechanical forces play particularly important roles in the regulation of connective tissues including not only bone and cartilage but also the interstitial tissues of most organs. In vivo studies have correlated changes in mechanical load to modulation of the extracellular matrix and have indicated that increased mechanical force contributes to the enhanced expression and deposition of extracellular matrix components or fibrosis. Pathological fibrosis contributes to dysfunction of many organ systems. A variety of in vitro models have been utilized to evaluate the effects of mechanical force on extracellular matrix-producing cells. In general, application of mechanical stretch, fluid flow, and compression results in increased expression of extracellular matrix components. More recent studies have indicated that tissue rigidity also provides profibrotic signals to cells. The mechanisms whereby cells detect mechanical signals and transduce them into biochemical responses have received considerable attention. Cell surface receptors for extracellular matrix components and intracellular signaling pathways are instrumental in the mechanotransduction process. Understanding how mechanical signals are transmitted from the microenvironment will identify novel therapeutic targets for fibrosis and other pathological conditions.

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Regulation of Matrix Assembly through Rigidity-dependent Fibronectin Conformational Changes

Cited by 46 publications

References 66 publications

Stimulatory effects of advanced glycation endproducts (AGEs) on fibronectin matrix assembly

Stimulatory effects of advanced glycation endproducts (AGEs) on fibronectin matrix assembly

Tissue stiffness regulates serine/arginine-rich protein-mediated splicing of the extra domain B-fibronectin isoform in tumors

Regulation of Tissue Fibrosis by the Biomechanical Environment

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