The ß subunit of soluble guanylyl cyclase GUCY1B3 exerts cardioprotective effects against ischemic injury via the PKCε/Akt pathway.

The soluble form of guanylyl cyclase (sGC) is the main receptor for the signaling agent nitric oxide (NO), which regulates cardiomyocyte contractile function and attenuates cardiomyocyte hypertrophy. sGC catalyzes the formation of cyclic guanosine monophosphate (cGMP), a regulator of vascular tone, and cardiac NO-sGC-cGMP signaling modulates cardiac stress responses, including ischemia and reperfusion (IR) injury. Here, we investigated the role of GUCY1B3 (the ß subunit of sGC) in cardiomyocyte IR injury and myocardial infarction (MI) in vitro and in vivo. GUCY1B3 was upregulated in neonatal rat ventricular myocytes in response to IR injury, and GUCY1B3 overexpression restored IR-induced cell death and apoptosis. Treatment with specific inhibitors of PKCδ, PKCε, and Akt suggested that the protective effects of GUCY1B3 were mediated by PKCε/Akt signaling. In a mouse model of coronary artery ligation-induced MI, GUCY1B3 silencing aggravated MI-induced cardiac dysfunction and increased infarct size and exacerbated cardiomyocyte apoptosis in association with the inactivation of PKCε and Akt. Our results suggest that GUCY1B3 exerts cardioprotective effects through the modulation of the PKCε/Akt activity and identify a potential mechanism involved in NO-sGC-cGMP signaling in the heart.

Cardioprotective Effects of SIRT6 in a Mouse Model of Transverse Aortic Constriction-Induced Heart Failure.

SIRT6, a member of the NAD (+)-dependent class III deacetylase sirtuin family, plays important roles in the maintenance of cardiovascular homeostasis. Telomere shortening is a risk factor for age-associated diseases, including heart disease. In the present study, we investigated the role of SIRT6 and telomerase in a mouse model of transverse aortic constriction (TAC)-induced heart failure. SIRT6, telomerase reverse transcriptase (TERT), and telomere repeat binding factor (TRF)-1 were significantly downregulated in TAC mice compared with their expression in sham-operated mice. Lentiviral vector-mediated overexpression of SIRT6 upregulated TERT and TRF1 and increased the survival of mice after TAC. Echocardiography and hemodynamic measurements as well as histological analyses indicated that SIRT6 overexpression attenuated TAC-induced heart dysfunction and decreased TAC-induced cardiac inflammatory responses, reducing cardiac fibrosis and decreasing infarct size. Taken together, our findings indicate that SIRT6 protects the myocardium against damage and this effect may be mediated by the modulation of telomeres. Our findings linking SIRT6 and telomere integrity in the heart warrant further investigation into the underlying mechanisms and support SIRT6 as a promising therapeutic target for the treatment of cardiovascular diseases.