RNA helicase DDX5 maintains cardiac function by regulating CamkIIδ alternative splicing [RNA-seq]

The cardiomyocyte-specific deletion of Ddx5 in mice resulted in heart failure characterized by diminished cardiac function, enlarged heart chambers, and heightened fibrosis. Proteomic analysis unveiled the involvement of DDX5 in RNA splicing within cardiomyocytes. Our study identified DDX5 as a regulator of the abnormal splicing of CamkIIδ, preventing the generation of CaMKIIδA. This isoform activates LTCC through serine phosphorylation of Cacna1c, disrupting Ca2+ homeostasis. Consistently, DDX5-depleted cardiomyocytes exhibited elevated intracellular Ca2+ transients and increased sarcoplasmic reticulum Ca2+ content.