Abstract 11801: Glycoprotein Nonmetastatic Melanoma Proteinbbregulates Lysosomal Integrity and Lifespan of Senescent Endothelial Cells

Abstract

Introduction: The accumulation of senescent cells during aging relates to the development of various age-related pathologies including atherosclerosis and heart failure, which can be improved by specific elimination of senescent cells, so called “senolysis”. We have identified glycoprotein nonmetastatic melanoma protein B (GPNMB) as an antigen specifically expressed by senescent endothelial cells, so called “seno-antigen”. Also, we previously developed the vaccine against Gpnmb, eliminated senescent cells in mice, leading to an improvement of age-related pathologies. However, detailed function of GPNMB in senescent cells is still uncertain. Purpose: To elucidate the role of GPNMB in senescent cells and cardiovascular-related pathologies. Methods: Overexpression or depletion of GPNMB in endothelial cells (ECs) were generated. Cellular senescence was induced in ECs by doxorubicin. Gpnmb-knockout or overexpressed (Gp-KO or Gp-OE) mice were generated and imposed to hind-limb ischemia treatment or high-fat-diet feeding to evaluate vascular functions. Double transgenic mice (ApoE-KO and Gp-KO or Gp-OE) were also generated and imposed to high-fat diet to develop atherosclerosis. Results: The depletion of GPNMB in ECs was proved to shorten their replicative lifespan, and increase the expression of negative cell cycle regulators including p53, p21 and p16. Conversely, overexpressed GPNMB protected ECs from senescence stress. In vivo studies showed the impairment of vascular function, atherogenesis, and endothelium-dependent vasodilatation were enhanced in Gp-KO mice, but attenuated in Gp-OE mice. Furthermore, GPNMB was found to localize on lysosomal membrane. Cells with depleted GPNMB demonstrated the accumulation of dysfunctional lysosomes, indicated the contribution of GPNMB in maintaining lysosome integrity. Under senescence-associated lysosomal stress, elevated GPNMB expression was detected, contributing to senescent cells survival. Conclusions: GPNMB acts as a protective factor to senescent cells. Seno-antigen targeting GPNMB is possibly considered as an efficient strategy against cardiovascular diseases and other age-associated disorders with higher selectivity and fewer off-target effects.