抄録
In cardiomyocytes, protein kinase D1 (PKD1) plays a central role in the response to stress signal. Neuro-humoral stimuli activate PKD1 that localizes at the Z-discs and phosphorylates several myofibril proteins, regulating the cardiac contraction. In the nucleus, PKD1 promotes the activation of gene transcription. We aimed to identify novel protein-PKD1 interactions. PKD1 interacting proteins were searched by yeast-two hybrid screening. We identified Enigma homolog 1 (ENH1) as a new binding partner of PKD1. Both ENH1 and PKD1 interact with α1C, the pore-forming subunit of the L-type voltage-gated calcium channels in neonatal rat cardiomyocytes. Silencing of ENH1, using RNA interference, prevented the binding of PKD1 to α1C. Moreover, a dominant negative mutant of PKD1 or the silencing of ENH1 inhibited the α-adrenergic-induced increase of L-type calcium currents. We found a new binding partner, ENH1, and a new target, α1C, for PKD1 in neonatal rat cardiomyocytes. Upon α-adrenergic stimulation, ENH1 scaffolds PKD1 to α1C to form a signaling complex which regulates the activity of cardiac L-type voltage-gated calcium channels. [J Physiol Sci. 2008;58 Suppl:S72]
