Abstract P313: Alterations in Notch Signaling in Diabetic Coronary Microvascular Smooth Muscle and Endothelial Cells

Abstract

Notch signaling between vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) is crucial during normal vascular development and homeostasis and may contribute to vasculopathies. Notch signaling is known to regulate VSMC phenotypic mechanisms, including proliferation and differentiation. We previously reported differences in VSCM Notch3 and EC Jagged1 mRNA expression, as well as a de-differentiated VSMC phenotype, in diabetic coronary resistance microvascular (CRM) cells as a potential mechanism for the inward remodeling observed in those vessels. The current study tested the hypothesis that VSMC-EC dependent Notch signaling accounts for phenotypic changes in VSMCs that may promote adverse remodeling observed in diabetic CRMs. Low-passage primary coronary VMSCs were isolated from normal (n=6) and type 2 diabetic db/db mice (n=4) and were either cultured alone or co-cultured with normal or type 2 diabetic human coronary microvascular endothelial cells (hCMECs), respectively. Notch2 expression was significantly attenuated in diabetic CRM VSMCs in both mono- and co-culture conditions (0.53±0.12 vs. 1.00±0.06, p <0.01 and 0.59±0.09 vs. 0.94±0.04, p <0.01, respectively). There were no significant differences in Hes1, and Hrt3 was increased in only normal VSMCs that were co-cultured with ECs. We further found that proliferation inhibitor p53 expression was significantly lower in diabetic CRM VSMCs in when co-cultured with ECs (0.78±0.15 vs. 1.34±0.13, p <0.01), and Smad3 was significantly reduced in diabetic co-cultured CRM VSMCs (0.90±0.02 vs. 1.14±0.06, p <0.05). Collectively, these data implicate that Notch signaling through p53 and Smad3 may account for phenotypic alterations of diabetic CRM VSMCs.