From the Department of Biomedical Engineering and.
From the Department of Biomedical Engineering and
J Biol Chem. 2018 Nov 30;293(48):18655-18666. doi: 10.1074/jbc.RA118.004020. Epub 2018 Oct 15.
Cellular responses to platelet-derived growth factor (PDGF) are altered in a variety of pathological conditions, including cancers, fibroses, and vascular diseases, making PDGF-induced signaling pathways important therapeutic targets. The limited success of therapies designed to impact PDGF pathways may be overcome with a clearer understanding of how cells integrate signals from PDGF and the extracellular matrix (ECM). Here, we assessed the effects of fibronectin matrix assembly on the responsiveness of mesenchymal cells to PDGF. Our results indicate that fibroblast-mediated assembly of fibronectin fibrils attenuates intracellular calcium release in response to PDGF. The dose-dependent inhibition of PDGF-induced intracellular calcium release was specific to the ECM form of fibronectin. Further, a recombinant protein engineered to mimic ECM fibronectin similarly attenuated intracellular calcium release in response to PDGF. Of note, fibronectin attenuated the PDGF-calcium signaling axis at the level of phosphoinositide 3-kinase (PI3K) activation. Interestingly, ECM fibronectin did not alter other intracellular signals activated by PDGF, including activation of PDGF receptor β, AKT Ser/Thr kinase, phospholipase Cγ1, and extracellular signal-regulated kinase 1/2 (ERK1/2). Rather, fibronectin inhibited activation of the p55 regulatory subunit of PI3K in response to a variety of stimuli, indicating that ECM fibronectin selectively attenuates the intracellular calcium release cascade while leaving intact other PDGF signaling pathways. Selective regulation of calcium signaling by ECM fibronectin via the p55 regulatory subunit of PI3K represents a mechanism by which cells tune their response to PDGF and may therefore serve as a target to selectively regulate one branch of PDGF signaling.
细胞对血小板衍生生长因子 (PDGF) 的反应在多种病理条件下发生改变，包括癌症、纤维化和血管疾病，这使得 PDGF 诱导的信号通路成为重要的治疗靶点。旨在影响 PDGF 途径的治疗方法的有限成功可能会通过更清楚地了解细胞如何整合来自 PDGF 和细胞外基质 (ECM) 的信号来克服。在这里，我们评估了纤连蛋白基质组装对间充质细胞对 PDGF 反应性的影响。我们的结果表明，成纤维细胞介导的纤连蛋白原纤维组装会减弱细胞内钙释放对 PDGF 的反应。PDGF 诱导的细胞内钙释放的剂量依赖性抑制是纤连蛋白 ECM 形式特异性的。此外，一种工程重组蛋白，设计用于模拟 ECM 纤连蛋白，也会减弱细胞内钙释放对 PDGF 的反应。值得注意的是，纤连蛋白在磷酸肌醇 3-激酶 (PI3K) 激活水平上减弱了 PDGF-钙信号轴。有趣的是，ECM 纤连蛋白不会改变 PDGF 激活的其他细胞内信号，包括 PDGF 受体 β、AKT Ser/Thr 激酶、磷脂酶 Cγ1 和细胞外信号调节激酶 1/2 (ERK1/2) 的激活。相反，纤连蛋白抑制了各种刺激物对 PI3K p55 调节亚基的激活，表明 ECM 纤连蛋白选择性地减弱细胞内钙释放级联，同时保持 PDGF 信号通路的其他途径完好无损。ECM 纤连蛋白通过 PI3K p55 调节亚基对钙信号的选择性调节代表了细胞调节其对 PDGF 反应的一种机制，因此可能成为选择性调节 PDGF 信号通路的一个分支的靶点。
