Selective expression of TSPAN2 in vascular smooth muscle is independently regulated by TGF-b1/smad and myocardin/serum response factor

Tetraspanins (TSPANs) comprise a large family of 4-trans membr anedoma in proteins. Theimportance of TSPANs in vascular smoothmuscle cells (VSMCs) is unexplored. Given that TGF-β1 and myocardin (MYOCD) are potent activators for VSMC differentiation, we screened for TGF-β1 and MYOCD/serum response factor (SRF)-regulated TSPANs in VSMC by using RNA-seqanalyses and RNA-arrays. TSPAN2was found to be the only TSPAN family gene induced by TGF-β1 and MYOCD, and reduced by SRF deficiency in VSMCs. We also found that TSPAN2 is highly expressed in smooth muscle-enriched tissues and down-regulated in in vitro models of VSMC pheno typi cmodulation. TSPAN2expressionis attenuatedinmouse carotid arteries after ligationinjury and infailed human arteriovenous fistula samples after occlusion by dedifferentiated neointimal VSMC. In vitro functional studies showed that TSPAN2 suppresses VSMC proliferation and migration. Luciferase reporter and chromatin immunopreci pitation assays demonstrated that TSPAN2 is regulated by 2 parallel pathways, MYOCD/SRF and TGF-β1/SMAD, via distinct binding elements within the proximal promoter. Thus, we identified the first VSMCenriched and MYOCD/SRF and TGF-β1/SMAD-dependent TSPAN familymember, whose expression is intimately associated with VSMC differentiation and negatively correlated with vascular disease. Our results suggest that TSPAN2mayplay important roles in vasculardisease.