LncRNA MALAT1 regulates diabetic cardiac fibroblasts through the Hippo-YAP signaling pathway.

Diabetic cardiomyopathy (DCM) is a major diabetes-related microvascular disease. LncRNA MALAT1 is widely expressed in cardiomyocytes responding to hypoxia and high levels of glucose (high glucose). In this study, cardiac fibroblasts (CFs) were transfected with si-MALAT1 and exposed to high glucose. CFs in the high glucose groups were treated with 30 mmol/L glucose, and the control CFs were treated with 5.5 mmol/L glucose. The expression of MALAT1 in the nucleus and cytoplasm of CFs was detected. The biological behavior of CFs, as well as collagen production, activity of the Hippo-YAP pathway, and nuclear localization of YAP were measured. Mouse models of DCM were established to observe the pathological changes to myocardium and determine the levels of collagen I, Bax, and Bcl-2. The interaction between MALAT1 and YAP was analyzed, and CREB expression in the high-glucose treated CFs was detected. MALAT1 was upregulated in high-glucose CFs and located in the nucleus. High-glucose increased collagen production, inflammation, cell proliferation, cell invasiveness, and phosphorylation of MST1 and LATS1, and also promoted nuclear translocation of . These trends in high-glucose treated CFs and the DCM mice were reversed by transfection with si-MALAT1. MALAT1 positively regulated the nuclear translocation of YAP by binding to CREB. CREB levels were increased in the high-glucose CFs, but decreased after silencing MALAT1. These results indicate that si-MALAT1 reduces inflammation and collagen accumulation in high-glucose CFs and DCM mice via the Hippo-YAP pathway and CREB.