Abstract 16560: Knock-Out of Canopy 2 Activates p16 Pathway to Impair Cardiac Regeneration
Introduction: Cardiac repair and regeneration depend on angiogenesis and cell proliferation. We discovered that Canopy 2 (CNPY2) was a secreted angiogenic growth factor which promotes neovascularization. Cardiac overexpression of CNPY2 in transgenic mice prevented ventricular dilatation following transverse aortic constriction. Here, we investigated the mediators and mechanisms responsible for these beneficial effects using CNPY2 knock-out (KO) mice.
Methods/Results: Cardiac tissue from 5 patients with end-stage heart failure had significantly lower endogenous CNPY2 expression than samples from 3 control patients. Similar to the human results, CNPY2 expression in mouse hearts decreased significantly following an MI. Following coronary ligation, significantly less cell proliferation was found in CNPY2 KO than wild-type (WT) mice which contributed to impaired angiogenesis and tissue repair and decreased cardiac function after MI (fractional shortening: WT: 21.1±2.1% vs. KO: 16.4±1.6%, p<0.01 at day 28 post-MI). RT-qPCR revealed significantly increased p16 expression in CNPY2 KO mouse hearts (WT: 1.0±0.1 vs. KO: 1.8±0.2 [relative expression of p16], p<0.05) which was confirmed by Western blot (WT: 0.43±0.04 vs. KO: 0.73±0.08 [% GAPDH], p<0.05) and immunostaining (WT: 21.6±2.3 vs. KO: 37.2±2.5 [% total cells], p<0.05) for the p16 protein. Expression of cell cycle-related proteins, cyclin D1 and CDK4 and 6, was significantly decreased in CNPY2 KO mouse hearts. MI exacerbated the detrimental effects of p16 on tissue regeneration with a greater increase in CNPY2 KO mice. Activation of the p16 pathway in KO mice was associated with overexpression of CNPY2 in the cardiac tissue of transgenic mice which reversed the inhibition of cell proliferation through suppression of the p16 pathway.
Conclusions: Cardiac injury and progressive heart failure were associated with decreased CNPY2 levels in both humans and mice. Knock-out of CNPY2 resulted in up-regulation of p16 which impaired cardiac function and tissue regeneration. These data suggest that CNPY2 is an important regulator of p16 and promotes cell proliferation and tissue regeneration through inhibition of the p16 pathway. CNPY2 treatment might be a new approach to restore function after an MI.
Author Disclosures: W. Yin: None. J. Guo: None. S. Li: None. P. Billia: None. J. Wu: None. R.D. Weisel: None. R. Li: Research Grant; Significant; Canadian Institutes of Health Research Foundation grant (332652).
- © 2016 by American Heart Association, Inc.