PDGF-DD, a novel mediator of smooth muscle cell phenotypic modulation, is upregulated in endothelial cells exposed to atherosclerosis-prone flow patterns

Abstract

GK. PDGF-DD, a novel mediator of smooth muscle cell phenotypic modulation, is upregulated in endothelial cells exposed to atherosclerosis-prone flow patterns. Am J Physiol Heart Circ Physiol 296: H442-H452, 2009. First published November 21, 2008 doi:10.1152/ajpheart.00165.2008.-Platelet-derived growth factor (PDGF)-BB is a well-known smooth muscle (SM) cell (SMC) phenotypic modulator that signals by binding to PDGF ␣␣-, ␣␤-, and ␤␤-membrane receptors. PDGF-DD is a recently identified PDGF family member, and its role in SMC phenotypic modulation is unknown. Here we demonstrate that PDGF-DD inhibited expression of multiple SMC genes, including SM ␣-actin and SM myosin heavy chain, and upregulated expression of the potent SMC differentiation repressor gene Kruppel-like factor-4 at the mRNA and protein levels. On the basis of the results of promoter-reporter assays, changes in SMC gene expression were mediated, at least in part, at the level of transcription. Attenuation of the SMC phenotypic modulatory activity of PDGF-DD by pharmacological inhibitors of ERK phosphorylation and by a small interfering RNA to Kruppel-like factor-4 highlight the role of these two pathways in this process. PDGF-DD failed to repress SM ␣-actin and SM myosin heavy chain in mouse SMCs lacking a functional PDGF ␤-receptor. Importantly, PDGF-DD expression was increased in neointimal lesions in the aortic arch region of apolipoprotein C-deficient (ApoE Ϫ/Ϫ ) mice. Furthermore, human endothelial cells exposed to an atherosclerosis-prone flow pattern, as in vascular regions susceptible to the development of atherosclerosis, exhibited a significant increase in PDGF-DD expression. These findings demonstrate a novel activity for PDGF-DD in SMC biology and highlight the potential contribution of this molecule to SMC phenotypic modulation in the setting of disturbed blood flow. shear stress; disturbed blood flow; smooth muscle myosin heavy chain; smooth muscle ␣-actin ATHEROSCLEROSIS IS A COMPLEX disease characterized by the accumulation of lipid and cholesterol deposits within the walls of blood vessels, as well as intimal proliferation and extracellular matrix deposition by phenotypically modulated smooth muscle (SM) cells (SMCs) (1). SMCs within human atherosclerotic lesions and experimental atherosclerosis exhibit a distinct morphological change compared with medial SMCs within the normal vessel wall (32). Along with this morphological change, phenotypically modulated SMCs exhibit decreased expression of a variety of contractile genes, including SM ␣-actin, SM myosin heavy chain (MHC), SM22␣, smoothelin, and h1-calponin (32). Advanced atherosclerotic lesions are characterized by a large lipid and necrotic core covered by a fibrous cap, and the thickness and mechanical properties of these lesions are key determinants of the probability of plaque rupture (3, 12, 13), thrombosis, and subsequent acute myocardial infarction or stroke, the leading causes of death in developed countries (3,12,13). Although the precise factors and mechanisms that con...

Extracellular Fluid Excess Is Significantly Associated With Coronary Artery Calcification in Patients With Chronic Kidney Disease

“…These signaling pathways induce the proliferation, migration, apoptosis, and osteoblastic differentiation of VSMCs, and altered VSMCs play a major role in vascular calcification 35, 36. Recent studies have shown that high shear stress induces apoptosis of VSMCs through nitric oxide released by endothelial cells,37 and low shear stress upregulates the proliferation and migration of VSMCs via platelet‐derived growth factor and transforming growth factor secreted by endothelial cells 38. Therefore, ECF excess may also be involved in vascular calcification through the cross‐talk between endothelial cells and VSMCs.…”

Biomechanical regulation of vascular smooth muscle cell functions: from in vitro to in vivo understanding

“…The mechanism involved is that low shear stress increases endothelial PDGF expression [116][117][118] and the upregulated expression of PDGF-DD in ECs mediates VSMC phenotypic modulation [119,120]. High shear stress protects ECs, even shear exceeding 1500 dyn cm 22 did not cause gross injury or denudation [121].…”

Interleukin-1β modulates smooth muscle cell phenotype to a distinct inflammatory state relative to PDGF-DD via NF-κB-dependent mechanisms

“…In addition, in vivo blockade of PDGF-BB or PDGFR-␤ reduces SMC migration into neointimal lesions after vascular injury and decreases SMC accumulation and fibrous cap formation within developing atherosclerotic plaques in mice (25,37,54,66,69). Recent studies have demonstrated that PDGF-DD, a newly discovered PDGF isoform that is a more selective agonist of the PDGFR-␤, also promotes SMC phenotypic modulation through repressing SMC differentiation marker gene expression and increasing SMC proliferation and migration (5,13,38,73). Genetic deletion of the PDGFR-␤ in cultured SMCs abrogated PDGF-DD-and PDGF-BB-induced repression of SMC differentiation marker genes, suggesting that these effects of PDGF on SMC phenotype are mediated via PDGFR-␤ activation (73).…”

“…Recent studies have demonstrated that PDGF-DD, a newly discovered PDGF isoform that is a more selective agonist of the PDGFR-␤, also promotes SMC phenotypic modulation through repressing SMC differentiation marker gene expression and increasing SMC proliferation and migration (5,13,38,73). Genetic deletion of the PDGFR-␤ in cultured SMCs abrogated PDGF-DD-and PDGF-BB-induced repression of SMC differentiation marker genes, suggesting that these effects of PDGF on SMC phenotype are mediated via PDGFR-␤ activation (73). These results suggest that multiple PDGF isoforms acting at the PDGFR-␤ mediate SMC phenotypic modulation in a way that resembles the classically defined switch from a contractile to a synthetic state observed within atherosclerotic lesions in vivo (10,64).…”