Chromodomain Helicase Binding Protein 8 (Chd8) Is A Novel A-Kinase Anchoring Protein Expressed During Rat Cardiac Development

A-kinase anchoring proteins (AKAPs) bind the regulatory subunits of protein kinase A (PKA) and localize the holoenzyme to discrete signaling microdomains in multiple subcellular compartments. Despite emerging evidence for a nuclear pool of PKA that rapidly responds to activation of the PKA signaling cascade, only a few AKAPs have been identified that localize to the nucleus. Here we show a PKA-binding domain in the amino terminus of Chd8, and demonstrate subcellular colocalization of Chd8 with RII. RII overlay and immunoprecipitation assays demonstrate binding between Chd8-S and RII alpha. Binding is abrogated upon dephosphorylation of RIIa. By immunofluorescence, we identified nuclear and perinuclear pools of Chd8 in HeLa cells and rat neonatal cardiomyocytes. We also show high levels of Chd8 mRNA in RNA extracted from postnatal rat hearts. These data add Chd8 to the short list of known nuclear AKAPs, and implicate a function for Chd8 in postnatal rat cardiac development.