Deletion of smooth muscle O-GlcNAc transferase prevents development of atherosclerosis in western diet-fed hyperglycemic ApoE -/- mice in vivo

Accumulating evidence highlights protein O-GlcNAcylation as a putative pathogenic contributor of diabetic vascular complications. We previously reported that elevated protein O-GlcNAcylation correlates with increased atherosclerotic lesion formation and VSMC proliferation in response to hyperglycemia. However, the role of O-GlcNAc transferase (OGT), regulator of O-GlcNAc signaling, in evolution of diabetic atherosclerosis remains elusive. The goal of this study was to determine whether smooth muscle OGT (smOGT) plays a direct role in hyperglycemia-induced atherosclerotic lesion formation and SMC de-differentiation. Using tamoxifen-inducible Myh11-CreER T 2 and OGT fl/fl mice, we generated smOGT WT and smOGT KO mice, with and without ApoE-null backgrounds. Following STZ-induced hyperglycemia, smOGT WT and smOGT KO mice were kept on standard laboratory diet for study duration. In a parallel study, smOGT WT ApoE -/- and smOGT KO ApoE -/- were kept on Western diet beginning 8-wks-age. Animals harvested at 14-16-wks-age were used for plasma and tissue collection. Loss of smOGT augmented SM contractile marker expression in aortic vessels of STZ-induced hyperglycemic smOGT KO mice. Consistently, smOGT deletion attenuated atherosclerotic lesion lipid burden (Oil red O), plaque area (H&E), leukocyte (CD45) and smooth muscle cell (ACTA2) abundance in Western diet-induced hyperglycemic smOGT KO ApoE -/- mice. This was accompanied with increased SM contractile markers, and reduced inflammatory and proliferative marker expression. Further, smOGT deletion attenuated YY1 and SRF expression (transcriptional regulators of SM contractile genes) in hyperglycemic smOGT KO ApoE -/- and smOGT KO mice. These data uncover an atheroprotective outcome of smOGT loss-of-function and suggest a direct regulatory role of OGT-mediated O-GlcNAcylation in VSMC de-differentiation in hyperglycemia.