Abstract 43: The Role of Epsins in Atherosclerosis
Background Epsins are a family of ubiquitin-binding, endocytic clathrin adaptors. Mice lacking both epsins 1 and 2 (Epn1/2) die at embryonic day 10 and exhibit an abnormal vascular phenotype. We have recently published that epsins function as regulators of tumor angiogenesis by controlling the endocytosis of VEGFR2 (J Clin Invest. 2012). The goal of this project is to define the novel role of epsins in endothelial cells (EC) in regulating inflammation-mediated atherogenesis.
Methods and results To examine the role of endothelial epsins in atherogenesis, we engineered mice with constitutive deletion of epsins in EC (EC-DKO). Strikingly, these mice are viable but display markedly attenuated atherogenesis on an ApoE null background in response to hypercholesterolemia. Oil red O staining revealed that ApoE-/- mice with endothelial deletion of epsins had a significant reduction in atherosclerotic lesion area in aortic root and macrophage infiltration compared to ApoE-/- mice after being fed a western diet for 10 weeks. FACS analysis revealed that deletion of epsins greatly reduced TNFα and LPS-induced expression of adhesion molecules (ICAM & VCAM), selectins (P- & E-), CCR2 and MCP-1 in primary mouse aortic EC (MAEC) isolated from EC-DKO mice. Mechanistically, epsins promote TNFR/TLRs signaling and NF-κB and MAPK (JNK and p38) activation by stabilizing the receptor complex formation and enhancing recruitment of NEMO, a crucial player in NF-kB activation. Conversely, epsin deficiency does not affect the surface expression of TNFR1/TLR2/4 by FACS analysis, suggesting that epsins may be dispensable for endocytosis of TNFR1/TLR2/4. We also observed that a synthetic peptide comprising the epsin ubiquitin-interacting motif (UIM) potently disrupts the association of epsins with TNFR/TLR signaling complex in vitro, suggesting a potential pharmacological inhibitory role for this peptide in controlling the atherosclerosis in vivo. Our data demonstrate that epsins control atherogenesis by regulating TNFR/TLR signaling in endothelial cells and provide a potential novel strategy to perturb atherogenesis.
Conclusion Our results demonstrated an essential role of epsins in atherogenesis by regulating TNFR/TLR signaling.
- © 2013 by American Heart Association, Inc.