Nesfatin-1 suppresses cardiac L-type Ca channels through melanocortin type 4 receptor and the novel protein kinase C theta isoform pathway

Abstract

Background/Aims: Nesfatin-1 (NF-1), an anorexic nucleobindin-2 (NUCB2)-derived hypothalamic peptide, acts as a peripheral cardiac modulator and it can induce negative inotropic effects. However, the mechanisms underlying these effects in cardiomyocytes remain unclear. Methods: Using patch clamp, protein kinase assays, and western blot analysis, we studied the effect of NF-1 on L-type Ca 2+ currents (I Ca,L ) and to explore the regulatory mechanisms of this effect in adult ventricular myocytes. Results: NF-1 reversibly decreased I Ca,L in a dose-dependent manner. This effect was mediated by melanocortin 4 receptor (MC4-R) and was associated with a hyperpolarizing shift in the voltage-dependence of inactivation. Dialysis of cells with GDP-β-S or anti-G β antibody as well as pertussis toxin pretreatment abolished the inhibitory effects of NF-1 on I Ca,L . Protein kinase C (PKC) antagonists abolished NF-1-induced responses, whereas inhibition of PKA activity or intracellular application of the fast Ca 2+ -chelator BAPTA elicited no such effects. Application of NF-1 increased membrane abundance of PKC theta isoform (PKC θ ), and PKC θ inhibition abolished the decrease in I Ca,L induced by NF-1. Conclusion: These data suggest that NF-1 suppresses L-type Ca 2+ channels via the MC4-R that couples sequentially to the βγ subunits of G i/o -protein and the novel PKC θ isoform in adult ventricular myocytes.