| Previous studies have shown that copper (Cu) supplementation at physiologically relevant levels reverses cardiac myocyte hypertrophy induced by phenylephrine (PE), and that this effect was VEGF-dependent. Yet, the amount of VEGF in the media was unchanged. However, we observed that Cu caused an increase in the ratio of VEGFR-1:VEGFR-2 as well as an increase in PKG-1 activity. PKG-1 activity is associated with the regression of cardiac myocyte hypertrophy. The present study was undertaken to test the hypothesis that VEGFR-1 is associated with PKG-1 and their association is involved in Cu induced regression of cardiomyocyte hypertrophy. Human cardiac myocytes (HCM) in cultures were exposed to phenylephrine (PE) at a final concentration of 100 muM for 48 hours to induce cell hypertrophy. Copper sulfate at a final concentration of 5 muM was added to the hypertrophic HCM cultures for 24 hours with the concomitant presence of PE to reverse the hypertrophy. Both hypertrophic and hypertrophic-reversed HCM cells underwent immunoprecipitation using anti-VEGFR-1 antibody or anti-PKG-1 antibody. The immune complex underwent gel-electrophoresis separation and Western blotting and LC-MS/MS analysis. Proteomic analysis identified Vimentin in the immune complexes that immunoprecipitated with VEGFR-1 and PKG-1. This study thus demonstrates that the association between VEGFR-1 with PKG-1 is mediated by Vimentin, and that Vimentin plays a critical role in copper regression of cardiac myocyte hypertrophy. |
