Abstract 12268: Overexpression of Endothelial p25 Causes Vascular Remodeling by Inducing Premature Aging

Abstract

Introduction: Cardiovascular diseases are the leading cause of disability and death worldwide. The cyclin-dependent kinase 5 (CDK5) signaling pathway has been implicated in the regulation of SIRT1, a mammalian longevity regulator involved in the cellular homeostasis and aging. However, the participation of p25, the regulatory subunit of CDK5 in cardiovascular diseases has not been fully understood. Hypothesis: Selective overexpression of p25 in the vascular endothelium leads to vascular remodeling by accelerating vascular aging. Methods: A transgenic mouse model with selective overexpression of p25 in endothelial cells (EC-p25) was established. Aortas were collected from 12- or 30-weeks old EC-p25 and control mice. Vascular tone response, vascular senescence, aortic stiffness and aortic wall hypertrophy were evaluated with wire myography, senescence-associated β-galactosidase (SA-β-gal), alizarin red and heamatoxylin-eosine staining respectively. Protein levels were measured by Western blotting. Primary porcine aortic endothelial cells (PAECs) were transfected with p25, Sirt1 and Sirt1 lacking deacetylase activity, cell death and senescence were evaluated. Sirt1 activity was measured in EC-p25 and Control mice. A p-value p<0.05 was considered as statistically significant. Results: Young EC-p25 mice exhibited increased vascular tone compared to the control mice. Alizarin red staining was more abundant in the aorta of 30 weeks old EC-p25 compared with the control mice, whereas SA-β-gal staining and aortic wall thickness were increased in EC-p25 mice. Overexpression of p25 in PAECs induced endothelial senescence and cell death. EC-p25 mice showed increased Sirt1 activity levels. Western blot analysis demonstrated that SIRT1 protein was fragmented in aorta of EC-p25 mice with increased levels of shorter fragments of Sirt1. PAECs transfected with Sirt1 mutant exhibited increased senescence. Conclusion: Selective overexpression of p25 in the vascular endothelium may regulate vascular remodeling by increasing vascular tone, vascular and endothelial senescence, aortic stiffness and aortic wall hypertrophy possible by modulating Sirt1 activity and integrity in the aorta of EC-p25 mice, accelerating premature vascular aging.