FGF12 Modulates Cardiomyocyte Hypertrophy by Inhibiting GATA4-ERK1/2 Phosphorylation Through Altered Intracellular Localization

BackgroundHypertrophic cardiomyopathy (HCM) is a heritable pathological condition resulting from mutations in sarcomere-related proteins, leading to severe structural abnormalities without effective treatment options. Although reduced fibroblast growth factor 12(FGF12) expression is observed in HCM patients, its functional role remains unclear. MethodsEmploying immunoprecipitation (IP)-mass spectrometry (MS) and CUT&Tag sequencing, we investigated FGF12-interacting proteins in myocardial samples from healthy volunteers and HCM patients. CRISPR-Cas9 was utilized to explore the function and interaction partners of FGF12 in cardiomyocytes induced from human pluripotent stem cells (hiPSCs-CMs), other cell lines, and mouse models (MYH7R403Q and MYBPC3c.790G>A, transverse aortic constriction (TAC)). During hypertrophy, FGF12 localizes intranuclearly, prompting investigations into its binding to gene promoter regions through CUT&Tag sequencing and dual-luciferase experiments using myocardial tissues from patients. The beating frequency of hiPS-CMs was assessed using the CardioExcyte 96 real-time label-free cardiomyocyte functional analysis system. ResultsFGF12 was found to associate with proteins involved in energy metabolism, predominantly localizing to the perinuclear space under physiological conditions but shifting into the nucleus of hypertrophic cardiomyocytes. Co-IP-MS revealed significant interactions between FGF12 and metabolism-associated proteins, particularly GATA binding protein 4 (GATA4) and mitogen-activated protein kinase 1/3 (MAPK1/3) in the perinuclear space. In a hypertrophic state, FGF12 bound to the GATA4 promoter region, increasing its expression upon nuclear translocation. Both in vitro and in vivo models demonstrated that FGF12 interaction with GATA4 inhibited GATA4 and MAPK1/3 phosphorylation, inducing the expression of hypertrophy-associated genes. Overexpression of FGF12-NLS-del (nuclear localization signal deletion) resulted in decreased GATA4 phosphorylation, suggesting inhibition in the perinuclear region. ConclusionsThis study elucidates a pathological mechanism of HCM involving FGF12, where its nuclear localization enhances phosphorylation, GATA4 expression, and activation of the ERK1/2-pGATA4 pathway genes associated with hypertrophy. Beyond advancing our understanding of HCM, these findings propose FGF12 as a potential therapeutic target for HCM, warranting further exploration to potentially alleviate this condition affecting millions of individuals.