Abstract 51: Thymosin β4 Targets Wisp1 to Protect Cardiomyocytes in AngII- induced Cardiac Hypertrophy

Abstract

Background: Thymosin beta-4 (Tβ4) is a ubiquitous protein with many properties relating to cell proliferation and differentiation that promotes wound healing and modulates inflammatory mediators. However, the role of Tβ4 in cardiomyocytes hypertrophy is currently unknown. The purpose of this study is to dissect the cardio-protective mechanism of Tβ4 in Ang II induced cardiac hypertrophy. Methods: Rat neonatal cardiomyocytes with or without Tβ4 pretreatment were stimulated with Ang II and expression of cell sizes, hypertrophy marker genes and Wnt signaling components was evaluated by quantitative real-time PCR, western blotting and fluorescent microscopy. Selected target gene Wisp-1 was either overexpressed or silenced by siRNA transfections in neonatal cardiomyocytes and effect of Tβ4 in Ang II-induced cardiac hypertrophy was evaluated. Results: Pre-treatment of Tβ4 resulted in reduction of cell sizes, hypertrophy marker genes and WNT-associated gene expression and levels induced by Ang II in cardiomyocytes. Tβ4 pretreatment also resulted in an increase in the expression of antiapoptotic proteins and reduction of Bax/BCl 2 ratio in the cardiomyocytes. Wisp-1 overexpression promotes cardiac hypertrophy and was reversed by pretreatment with Tβ4. Knocking down of Wisp1 partly rescue the cells from hypertrophic response after Tβ4 treatment. Conclusion: This is the first report that demonstrates the effect of Tβ4 on cardiomyocytes hypertrophy and its capability to selectively target Wisp-1 in neonatal cardiomyocytes thus preventing cell death, thereby, protecting the myocardium. Wisp-1 promotes the cardiac hypertrophy which was prevented by Tβ4 treatment.