Wnt4/β-Catenin Signaling Induces VSMC Proliferation and Is Associated With Intimal Thickening

Abstract

Rationale: Vascular smooth muscle cell (VSMC) proliferation causes intimal thickening in atherosclerosis andrestenosis. Previously, we demonstrated that Wnt/␤-catenin signaling upregulates VSMC proliferation in vitro.Objective: We examined this pathway in vivo and investigated the involvement of specific Wnt proteins in VSMC proliferation. Methods and Results:Left carotid arteries of TOPgal (␤-catenin signaling reporter) transgenic mice were ligated to induce intimal thickening. ␤-Catenin signaling was induced in the media and intima at 3 and 28 days after ligation, respectively, and was associated with VSMC proliferation and cyclin D1 expression. In vitro, a Wnt agonist promoted mouse VSMC proliferation, whereas Wnt inhibitory factor (WIF)-1 retarded platelet-derived growth factor-BB (PDGF-BB)-induced VSMC proliferation. Microarray analysis and quantitative PCR detected a significant induction of Wnt2 and Wnt4 mRNA in PDGF-BB-treated (proliferating) VSMCs compared to quiescent VSMCs. Western blotting revealed this increase was only translated into protein for Wnt4. Specific silencing RNA knockdown of Wnt4, but not Wnt2, significantly reduced VSMC proliferation. Recombinant Wnt4, but not Wnt2, significantly increased VSMC proliferation by Ϸ2-fold and silencing RNA knockdown revealed this is via Frizzled 1. Immunohistochemistry showed that increased Wnt4 protein correlated with VSMC proliferation and cyclin D1 expression (P<0.05 and P<0.001, respectively) during intimal thickening after rat carotid artery injury. Importantly, we also showed that intimal thickening and VSMC proliferation after carotid artery ligation was significantly retarded in Wnt4 ؉/؊ compared to Wnt4 ؉/؉ mice. nappropriate vascular smooth muscle cell (VSMC) activation plays a key role in pathologies that involve intimal thickening, such as atherosclerosis and restenosis after angioplasty and vein grafting. 1,2 Intimal thickening occurs as a result of augmented VSMC proliferation, in addition to increased VSMC migration, extracellular matrix synthesis and phenotypic change. 3 Recently, we and others have proposed that the Wnt/␤-catenin pathway is a novel regulator of VSMC proliferation and thereby intimal thickening. 4 -10 The Wnt family (comprised of 19 secreted, lipid-modified glycoproteins) plays a crucial role not only in the regulation of embryogenesis and development, but also in cell proliferation, differentiation, polarity, migration, and invasion (see review 11 ). Wnt proteins activate downstream signaling pathways (in a paracrine and autocrine manner) after binding to cell surface Frizzled (Fzd) receptors. 12 Abnormal Wnt signaling is associated with many human diseases, including cancer and degenerative diseases 11 ; however, the involvement of Wnt signaling in atherosclerosis and restenosis remains to be fully elucidated. ConclusionsAlthough Wnt signaling via ␤-catenin has a recognized role in controlling the proliferation of cells in human cancers, 13 its role in VSMCs has only recently been considered. We previously showed that ...

Long Noncoding RNA-GAS5

“…[35][36][37] VSMC function and intimal thickening also can be regulated by β-catenin signaling. [38][39][40] Given the role of GAS5 in regulating β-catenin nuclear translocation, we can conclude that GAS5 regulates EC and VSMC function and vascular remodeling through β-catenin signaling.…”

Atherosclerotic Calcification: Wnt Is the Hint

“…Synthesis of extracellular matrix by VSMCs, along with inflammatory cell invasion, thickens the arterial wall 1, 30. When lipids begin to accumulate in the vessel wall, modification via aggregation induces lipid uptake in macrophages, creating foam cells 6, 7.…”

“…In addition, there are suggestions that an obstructive calcified lesion is more stable than a nonobstructive thin‐cap fibroatheroma, because the calcified plaque leads to stable angina pectoris, whereas the fibroatheroma has a tendency to rupture 36. Thus, calcification may be paradoxically beneficial, despite its associations with cardiovascular morbidity and mortality 30. Conversely, the increased incidence of disease and death with VC may not be a direct effect of calcification itself, but rather the fact that calcification is found in advanced atherosclerotic lesions 37…”

Orphan Nuclear Receptor Nur77 Inhibits Angiotensin II–Induced Vascular Remodeling via Downregulation of β-Catenin

“…14,15 Many studies have revealed the critical pathophysiological roles of the Wnt/β-catenin pathway in vascular remodeling. [16][17][18][19] Tsaousi et al 18 found that Wnt4/β-catenin signaling induces VSMC proliferation and is associated with intimal thickening in ligated arteries. Diverse physiological stimuli, including oxidized low-density lipoprotein and growth factors, activate β-catenin signaling in VSMCs.…”