PCBP2 Promotes NRG4 mRNA Stability to Diminish Angiotensin II-Induced Hypertrophy, NLRP3 Inflammasome Activation, and Oxidative Stress of AC16 Cardiomyocytes.

Myocardial hypertrophy, a complex cardiovascular disorder, remains a significant challenge. NRG4 has shown protective effects against myocardial damage. Here, we clarified the role of NRG4 in angiotensin II (Ang II)-induced hypertrophy of AC16 cardiomyocytes. The Ang II-stimulated AC16 cell line was used as an in vitro model of myocardial hypertrophy. Immunofluorescence using an anti-α-actinin antibody was used to observe cell area and size. mRNA expression was detected by quantitative PCR, and protein levels were measured by immunoblot assay. ROS amount detection was performed by flow cytometry. The cell protein/DNA ratio and the levels of IL-1β, IL-18, MDA and SOD were tested using commercial kits. The relationship between PCBP2 and NRG4 mRNA was validated by luciferase, RNA immunoprecipitation (RIP), and mRNA stability assays. In Ang II-stimulated AC16 cells, PCBP2 and NRG4 were markedly downregulated. Increased NRG4 expression relieved Ang II-induced hypertrophy and fibrosis in AC16 cardiomyocytes. Moreover, NRG4 increase weakened NLRP3 inflammasome activation and oxidative stress in Ang II-stimulated AC16 cardiomyocytes. Mechanistically, PCBP2 stabilized NRG4 mRNA to increase NRG4 protein expression in Ang II-induced AC16 cardiomyocytes. NRG4 depletion counteracted the suppressive effects of PCBP2 upregulation on hypertrophy, NLRP3 inflammasome activation, and oxidative stress of Ang II-induced AC16 cardiomyocytes. Additionally, the PCBP2/NRG4 cascade regulated the AMPK/mTOR signaling pathway in Ang II-induced AC16 cardiomyocytes. Our data demonstrate that the previously uncharacterized PCBP2/NRG4 cascade attenuates Ang II-triggered hypertrophy, NLRP3 inflammasome activation, and oxidative stress of AC16 cardiomyocytes.