Induction of tenascin-C by cyclic tensile strain versus growth factors: distinct contributions by Rho/ROCK and MAPK signaling pathways

Abstract

Expression of the extracellular matrix (ECM) protein tenascin-C is induced in fibroblasts by growth factors as well as by tensile strain. Mechanical stress can act on gene regulation directly, or indirectly via the paracrine release of soluble factors by the stimulated cells. To distinguish between these possibilities for tenascin-C, we asked whether cyclic tensile strain and soluble factors, respectively, induced its mRNA via related or separate mechanisms. When cyclic strain was applied to chick embryo fibroblasts cultured on silicone membranes, tenascin-C mRNA and protein levels were increased twofold within 6 h compared to the resting control. Medium conditioned by strained cells did not stimulate tenascin-C mRNA in resting cells. Tenascin-C mRNA in resting cells was increased by serum; however, cyclic strain still caused an additional induction. Likewise, the effect of TGF-beta1 or PDGF-BB was additive to that of cyclic strain, whereas IL-4 or H2O2 (a reactive oxygen species, ROS) did not change tenascin-C mRNA levels. Antagonists for distinct mitogen-activated protein kinases (MAPK) inhibited tenascin-C induction by TGF-beta1 and PDGF-BB, but not by cyclic strain. Conversely, a specific inhibitor of Rho-dependent kinase strongly attenuated the response of tenascin-C mRNA to cyclic strain, but had limited effect on induction by growth factors. The data suggest that regulation of tenascin-C in fibroblasts by cyclic strain occurs independently from soluble mediators and MAPK pathways; however, it requires Rho/ROCK signaling.

ROCK2/rasHa co-operation induces malignant conversion via p53 loss, elevated NF-κB and tenascin C-associated rigidity, but p21 inhibits ROCK2/NF-κB-mediated progression

“…1,2,13 Previous K14.ROCK er studies demonstrated ROCK-associated collagen deposition resulted in a stiffened ECM and increased tissue rigidity. 5 Similarly human cutaneous SCCs demonstrated ROCK2/p-Mypt1 staining correlated with MLC2 phosphorylation and actomyosin contractility; 6 suggesting a mechano-transduction pathway facilitated progression by providing the mobility/flexibility necessary to invade tissues with increased rigidity, [6][7][8] ideas supported by analysis of tenascin C [28][29][30] and p-Mypt1 inactivation.…”

“…Tenascin C is a large ECM/molecule associated with alterations in rigidity that drive progression [27][28][29] and previously linked with activated Rho/Rock and MAP Kinase signalling. 28,29 Tenascin C expression reflects tumour aggression and metastatic potential 27,[48][49][50] and also associated with deregulated NF-κβ signalling 48 and NF-κβ roles in inflammation.…”

“…In normal tissues, ECM expression of tenascin C is low but levels increase during tumour progression and given the interrelationship between ROCK2-associated collagen deposition and resultant integrin-mediated in the extracellular matrix, 4-6 tenascin C levels were analysed to assess stage-specific roles and whether expression reflected increased tissue stiffness. [27][28][29] 4HT-treated K14.ROCK er /HK1.ras 1205 invade. In addition, whilst papilloma outgrowths displayed elevated p-Mypt1, expression was again confined to super-basal layers, alongside supra-basal ROCK2 due to intense basal-layer p21 expression.…”

Mechanoregulation of gene expression in fibroblasts

“…Mechanoregulation of gene expression has been widely studied in chicken skin fibroblasts, and various mechanisms have been proposed for the mechanoregulation of ECM genes (Chiquet-Ehrismann et al, 1994;Chiquet et al, 1996Chiquet et al, , 2003Chiquet et al, , 2004Sarasa-Renedo and Chiquet, 2005;Sarasa-Renedo et al, in press). The genes of focus in these studies are tenascin-C and collagen fibril-associated type XII collagen.…”

“…The resulting increase in force at focal complexes triggers the transition of these structures into focal contacts. It has been shown that ROCK inhibitor attenuates cyclic stretching-mediated tenascin-C mRNA induction, and ROCK stimulators act synergistically with cyclic stretching to induce tenascin-C, suggesting a direct correlation between the tenascin-C gene induction and ROCK-mediated cytoskeletal tension (Chiquet et al, 2004;Sarasa-Renedo et al, in press). …”