The Stiffness of Cardiac Fibroblast Substrates Exerts a Regulatory Influence on Collagen Metabolism via α2β1 Integrin, FAK and Src Kinases

Abstract

Information about mechanical strain in the extracellular space is conducted along collagen fibers connected with integrins and then transmitted within cells. An aim of the study is to verify the hypothesis that the stiffness of cardiac human fibroblast substrates exerts a regulatory effect on collagen metabolism via integrin α2β1 and downstream signaling. The experiments were performed on human cardiac fibroblasts cultured on stiff or soft polyacrylamide gels. Extracellular and intracellular collagen content, metalloproteinase-1 (MMP-1), metalloproteinase-9 (MMP-9) and expression of the α1 chain of the procollagen type I gene (Col1A1) were elevated in cultures settled on soft substrate. The substrate stiffness did not modify tissue inhibitors of matrix metalloproteinase capacity (TIMPs 1–4). Integrin α2β1 inhibition (TC-I 15) or α2 subunit silencing resulted in augmentation of collagen content within the culture. Expression of Col1A1 and Col3A1 genes was increased in TC-I 15-treated fibroblasts. Total and phosphorylated levels of both FAK and Src kinases were elevated in fibroblasts cultured on stiff substrate. Inhibition of FAK (FAK kinase inhibitor 14) or Src kinase (AZM 47527) increased collagen content within the culture. The substrate stiffness exerted a regulatory influence on collagen metabolism via integrin α2β1 and its downstream signaling (FAK and Src kinases) in cardiac fibroblasts.

PRPF19 facilitates colorectal cancer liver metastasis through activation of the Src -YAP1 pathway via K63-linked ubiquitination of MYL9

“…Next, we focused on exploring the molecular mechanisms by which the PFPF19/MYL9 axis promoted metastasis in CRC cells. Notably, previous studies have revealed that cytoskeletal tension and matric stiffness can activate the expression of Src [30][31][32], and actomyosin contractility and Src function are required for YAP1 activation by stiff matrices [19]. Moreover, high ECM stiffness could directly lead to nuclear localization and subsequent transcriptional activity of YAP1 [33,34], while actomyosin inhibition blocks the matrix remodeling and YAP1 activation, all of which implies that a functional contractile cytoskeleton is necessary for the activation of YAP1.…”

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“…By transmitting mechanical cues into biochemical signals, cells respond through transcriptional regulation in the nucleus [ 93 , 105 ]. Gałdyszyńska M et al found α2β1 integrin and its downstream FAK/Src kinase signaling regulated collagen metabolism in cardiac fibroblasts cultured on the stiffer substrate, collagen content was elevated and regulated by MMP-1 and MMP-9 on soft substrates [ 106 ]. Yes-associated protein/transcriptional co-activator with PDZ-binding motifs (YAP/TAZ) are transcriptional co-activators that play a key role in the Hippo signaling pathway and are involved in various cellular processes.…”

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“…140 Moreover, scaffold stiffness regulates collagen metabolism in cardiac fibroblasts via integrin α2β1 and downstream signaling. 141…”

“…140 Moreover, scaffold stiffness regulates collagen metabolism in cardiac fibroblasts via integrin α2β1 and downstream signaling. 141 The viscoelasticity of hydrogels influences cell spreading, proliferation, migration and differentiation. In particular, cell spreading increased on elastic substrates, e.g.…”