Abstract P170: Targeting Angiotensin Ii-induced Endoplasmic Reticulum Stress In Vsmcs To Reduce Pathological Vascular Amyloid Burden And Remodeling

Abstract

Hypertension is a complex disorder and risk factor for cardiovascular disease, ultimately contributing to premature death. The societal burden of hypertension is enormous, therefore better understanding of molecular mechanisms underlying hypertension and associated pathological vascular remodeling is needed for mechanism-targeted therapy development. Endoplasmic reticulum (ER) stress occurs in cells under increased protein synthesis, Ca 2+ flux, or ROS generating environments- all of which are induced by Angiotensin II signaling in vascular cells. ER stress leads to the accumulation of misfolded proteins, and mediates cell death, fibrotic, and hypertrophic responses. The aim of this study was to target ER stress via chemical chaperone 3-hydroxy-2-naphthoic acid (3HNA) or genetic overexpression of chaperone glucose-regulated protein 78 (GRP78) to reduce protein aggregation and pathological response in VSMCs. Rat primary VSMCs were treated with 500 μM 3HNA or 30 MOI lacZ-GRP78 prior to stimulation with Ang II (100 nM). Protein synthesis assessed via puromycin incorporation revealed ER stress inhibition blocked Ang II associated protein synthesis in VSMCs, fold change relative to control of 1.7 (saline + Ang II) to 1.2 (3-HNA + Ang II) treated cells (P<0.05). GRP78 overexpression attenuated Ang II induction pre-amyloid oligomers (P<0.01) from 2.1 aggregates/cell to 0.9 aggregates/cell. Proteomic assessment of aggregates revealed Ang II induced crystallin AB (1.3 fold rel to control), HSP70 (1.716 fold rel to control) and annexin a2 (1.3 fold increase) enrichment in detergent insoluble fractions, which was attenuated by GRP78 overexpression (P=0.03, 0.03, and 0.024, respectively). In a 2 week Ang II infusion model, 3HNA was injected in C57/Bl6 mice. Ang II-induced medial thickness and cardiac vessel fibrosis was significantly reduced by 3-HNA (P<0.05). SM22α Cre GRP78 mice were generated and found protective against Ang II induced cardiac hypertrophy via HW/BW ratio (Cre- vs Cre+ Ang II P<0.05), and a trend in reduction of aortic medial thickness (P=0.098). Overall, GRP78 chaperone expression reduced protein aggregation and subsequent vascular remodeling induced by hypertensive stimulus and may elude novel therapeutic targets.