title: Nesfatin-1 Suppresses Cardiac L-type Ca²⁺ Channels Through Melanocortin Type 4 Receptor and the Novel Protein Kinase C Theta Isoform Pathway.
abstract: OBJECTIVE
  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 Ca2+ currents (ICa,L) and to explore the regulatory mechanisms of this effect in adult ventricular myocytes.
  
  
  RESULTS
  NF-1 reversibly decreased ICa,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-Gβ antibody as well as pertussis toxin pretreatment abolished the inhibitory effects of NF-1 on ICa,L. Protein kinase C (PKC) antagonists abolished NF-1-induced responses, whereas inhibition of PKA activity or intracellular application of the fast Ca2+-chelator BAPTA elicited no such effects. Application of NF-1 increased membrane abundance of PKC theta isoform (PKCθ), and PKCθ inhibition abolished the decrease in ICa,L induced by NF-1.
  
  
  CONCLUSIONS
  These data suggest that NF-1 suppresses L-type Ca2+ channels via the MC4-R that couples sequentially to the βγ subunits of Gi/o-protein and the novel PKCθ isoform in adult ventricular myocytes.
authors.forename: Jiaoqian
authors.initials: J
authors.lastname: Ying
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shan
authors.initials: S
authors.lastname: Gong
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Chang
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zhou
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Tao
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhang
mesh_terms: D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D000080866:Nucleobindins; D011493:Protein Kinase C / Q000378:metabolism*; D000074121:Protein Kinase C-theta; D017208:Rats, Wistar; D044105:Receptor, Melanocortin, Type 4 / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D020746:Calcium Channels, L-Type; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D009419:Nerve Tissue Proteins; C000630652:Nucb1 protein, rat; D000080866:Nucleobindins; D044105:Receptor, Melanocortin, Type 4; C489591:Prkcq protein, rat; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta; D019206:GTP-Binding Protein alpha Subunits, Gi-Go