CircRNA DICAR as a novel endogenous regulator for diabetic cardiomyopathy and diabetic pyroptosis of cardiomyocytes

In this study, we identified that a conserved circular RNA (circRNA) DICAR, which was downregulated in diabetic mouse hearts. DICAR had an inhibitory effect on diabetic cardiomyopathy (DCM), as the spontaneous cardiac dysfunction, cardiac cell hypertrophy, and cardiac fibrosis occurred in DICAR deficiency (DICAR(+/-)) mice, whereas the DCM was alleviated in DICAR-overexpressed DICAR(Tg) mice. At the cellular level, we found that overexpression of DICAR inhibited, but knockdown of DICAR enhanced the diabetic cardiomyocyte pyroptosis. At the molecular level, we identified that DICAR-VCP-Med12 degradation could be the underlying molecular mechanism in DICAR-mediated effects. The synthesized DICAR junction part (DICAR-JP) exhibited a similar effect to the entire DICAR. In addition, the expression of DICAR in circulating blood cells and plasma from diabetic patients was lower than that from health controls, which was consistent with the decreased DICAR expression in diabetic hearts. DICAR and the synthesized DICAR-JP may be drug candidates for DCM.

Automated summary

We found that DICAR, a conserved circRNA, was downregulated in diabetic mouse hearts. DICAR had an inhibitory effect on diabetic cardiomyopathy (DCM), and its deficiency led to cardiac dysfunction, hypertrophy, and fibrosis in mice. On the molecular level, DICAR-VCP-Med12 degradation could be the underlying mechanism for DICAR-mediated effects. The synthesized DICAR-JP showed similar effects, and the expression of DICAR in diabetic patients was lower than in healthy controls, suggesting that DICAR and DICAR-JP could be potential drug candidates for DCM.