Kallistatin/Serpina3c inhibits cardiac fibrosis after myocardial infarction by regulating glycolysis via Nr4a1 activation

Background: Fibrotic remodeling is an essential aspect of heart failure. Human kallistatin (KS, mouse Serpina3c homologs) inhibits fibrosis after myocardial infarction (MI) but the specific underlying mechanism is unknown. Methods: A total of 40 heart failure patients (HFPs) were enrolled and their plasma KS was measured using ELISA. Serpina3c(-/-) and C57BL/6 mice were used to construct the MI model. TGF-beta 1 or a hypoxic condition was established to interfere with the functioning of cardiac fibroblasts (CFs). RNA-seq was performed to assess the effect of Serpina3c on the transcriptome. Findings: The levels of KS were used as a predictor of readmission among the HFPs. Serpina3c expression decreased in MI hearts and CFs. Serpina3c(-/-) led to the aggravation of MI fibrosis, and increased the proliferation of CFs. The overexpression of Serpina3c in CFs had the opposite effect. Glycolysis-related genes were significantly increased in Serpina3c(-/-) group by RNA-seq. Enolase (ENO1), which is a key enzyme in glycolysis, increased most significantly. Inhibition of ENO1 could antagonize the promotion of Serpina3c(-/-) on the proliferation of CFs. Co-IP was performed to verify the interaction between Serpina3c and Nr4a1. Serpina3c(-/-) inhibited the acetylation of Nr4a1 and increased the degradation of Nr4a1. Activation of Nr4a1 could negatively regulate the expression of ENO1 and inhibited the proliferation of Serpina3c(-/-) CFs in Serpina3c(-/-) MI mice. Interpretation: Serpina3c inhibits the transcriptional activation of ENO1 by regulating the acetylation of Nr4a1, thereby reducing the fibrosis after MI by inhibiting glycolysis. Serpina3c is a potential target for prevention and treatment of heart failure after MI.