CCN2 activates ERK-signaling via integrin αv and enhances the interaction of ERK and DUSP6 in lymphatic endothelial cells

Abstract

Cellular communication network factor 2 (CCN2, also known as CTGF), is a modular and matricellular protein and a well-known angiogenic factor in physiological and pathological angiogenesis. However, its roles in lymphangiogenesis and intracellular signaling in lymphatic endothelial cells (LECs) remain unclear. Here, we investigated CCN2 signaling in LECs and its effects on lymphangiogenesis. In primary cultured LECs, gene expressions of lymphatic endothelial markers lymphatic vessel endothelial hyaluronan receptor 1 (Lyve1), Podoplanin and prospero homeobox 1 (Prox1) and lymphangiogenic factors vascular endothelial cell growth factor c (Vegfc), vascular endothelial cell growth factor d (Vegfd) and fms-related tyrosine kinase 4 (Flt4, also known as Vegfr3) were upregulated by CCN2. Subsequently, we found that CCN2 induced phospho-ERK and that was decreased by suppression of integrin v. CCN2 slightly decreased the growth of LECs due to enhancement of the interaction of ERK and dual specific protein phosphatase 6 (DUSP6), and knockdown of DUSP6 increased CCN2-induced phospho-ERK levels. In in vivo Matrigel plug assays, the number of Podoplanin-positive vessels was increased by exogenous CCN2, and phospho-ERK-positive LEC and DUSP6-positive LEC were detected in CCN2 plugs. These results suggest that CCN2-related lymphangiogenesis is regulated by DUSP6, which enables negative modulation of ERK-signaling.