Mechanical Stretch Increases MMP-2 Production in Vascular Smooth Muscle Cells via Activation of PDGFR-β/Akt Signaling Pathway

Kyo Won Seo,Seung Jin Lee,Chi Dae Kim,Jin Ung Bae,Yun Hak Kim,Sun Sik Bae,So Youn Park,Sadashiva Karnik

doi:10.1371/journal.pone.0070437

Abstract

Increased blood pressure, leading to mechanical stress on vascular smooth muscle cells (VSMC), is a known risk factor for vascular remodeling via increased activity of matrix metalloproteinase (MMP) within the vascular wall. This study aimed to identify cell surface mechanoreceptors and intracellular signaling pathways that influence VSMC to produce MMP in response to mechanical stretch (MS). When VSMC was stimulated with MS (0–10% strain, 60 cycles/min), both production and gelatinolytic activity of MMP-2, but not MMP-9, were increased in a force-dependent manner. MS-enhanced MMP-2 expression and activity were inhibited by molecular inhibition of Akt using Akt siRNA as well as by PI3K/Akt inhibitors, LY293002 and AI, but not by MAPK inhibitors such as PD98059, SP600125 and SB203580. MS also increased Akt phosphorylation in VSMC, which was attenuated by AG1295, a PDGF receptor (PDGFR) inhibitor, but not by inhibitors for other receptor tyrosine kinase including EGF, IGF, and FGF receptors. Although MS activated PDGFR-α as well as PDGFR-β in VSMC, MS-induced Akt phosphorylation was inhibited by molecular deletion of PDGFR-β using siRNA, but not by inhibition of PDGFR-α. Collectively, our data indicate that MS induces MMP-2 production in VSMC via activation of Akt pathway, that is mediated by activation of PDGFR-β signaling pathways.

Highlights

Excess hemodynamic forces, leading to mechanical stretch (MS) in vascular smooth muscle cells (VSMC), play an important role in vascular remodeling and atherosclerotic lesion formation [1], [2]
MS enhances matrix metalloproteinases (MMP)-2 activity and production in VSMC MMP activity was measured using extracts prepared from culture media of primary VSMC exposed to MS
Gelatin zymography showed that MS increased MMP-2 activity, but not MMP-9, in force (5 and 10%)- and time (6 and 12 hrs)-dependent manners (Figure 1A and 1B)

Summary

Introduction

Excess hemodynamic forces, leading to mechanical stretch (MS) in VSMC, play an important role in vascular remodeling and atherosclerotic lesion formation [1], [2]. The complex process of vascular remodeling involves enhanced collagen decomposition and extracellular matrix reorganization [3]. These processes are regulated by the enzymatic activity of matrix metalloproteinases (MMP) within the vascular wall [4], [5]. MMP-2 expression in VSMC is significantly increased in vulnerable regions of atherosclerotic plaques [8], [9], suggesting a pathogenic role for MMP-2 in the progression of plaque rupture in hypertension-related atherosclerosis. Regulation of MMP activity may occur at multiple levels either by gene transcription and synthesis of inactive proenzymes, post translational activation of proenzymes, or via the interaction of secreted MMP with their inhibitors named tissue inhibitors of metalloproteinases [10]. Besides enzymatic activation by other proteases [11], Akt signaling pathways are known to enhance MMP expression and activity in vitro study [12], [13]

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