FGF13 is a novel regulator of NF-κB and potentiates pathological cardiac hypertrophy

Summary FGF13 is an intracellular FGF factor. Its role in cardiomyopathies has been rarely investigated. We revealed that endogenous FGF13 is up-regulated in cardiac hypertrophy accompanied by increased nuclear localization. The upregulation of FGF13 plays a deteriorating role both in hypertrophic cardiomyocytes and mouse hearts. Mechanistically, FGF13 directly interacts with p65 by its nuclear localization sequence and co-localizes with p65 in the nucleus in cardiac hypertrophy. FGF13 deficiency inhibits NF-κB activation in ISO-treated NRCMs and TAC-surgery mouse hearts, while FGF13 overexpression shows the opposite trend. Moreover, FGF13 overexpression alone is sufficient to activate NF-κB in cardiomyocytes. Neither the interaction between FGF13 and p65 nor the effects of FGF13 on NF-κB has nothing to do with IκB. Together, an IκB-independent mechanism for NF-κB regulation has been revealed in cardiomyocytes both under basal and stressful conditions, suggesting the promising application of FGF13 as a therapeutic target for pathological cardiac hypertrophy and heart failure.