Abstract
The melanocortin-3 receptor, MC3-R, is abundant in the brain and is activated by γ-2-melanocyte stimulating hormone (γ-2-MSH). We have previously reported the translocation of protein kinase C (PKC) in spontaneous hypertensive rat (SHR) brain synaptosomes treated with γ-2-MSH. In this study, the expression of PKA and the related PKB in SHR brain synaptosomes was analyzed. PKA was detected in total synaptosomal fractions but not in particulate fractions, whereas PKB was not detected in either fraction. We next tested the hypothesis that the PKC pathway is involved in MC3-R signaling in a neuronal, CAD, cell line. Mobilization of intracellular Ca 2+ was analyzed by dual fluorescence imaging of Fura-2AM loaded MC3-R transfected cells. An increase in intracellular Ca 2+ was observed upon treatment with γ-2-MSH. A MC3-R-green fluorescent protein (GFP) fusion protein was expressed and shown to localize mainly to the plasma membrane in the soma and to neurites in differentiated CAD cells. Treatment with γ-2-MSH led to a punctate appearance and co-immunoprecipitation of the receptor fusion protein with protein kinase C-γ (PKC-γ). Differentiation of some neuronal cells has been shown to be associated with changes in the expression levels of protein kinase C isoenzymes. Induction of CAD cell differentiation was associated with down-regulation of the atypical PKC-ζ and protein kinase B (PKB/Akt1), that was less pronounced in MC3-R transfected cells. However, the levels of classical PKC isozymes, PKC-α, PKC-γ, and PKC-β were unchanged. These studies therefore indicate a role for PKC isozymes in γ-2-MSH/MC3-R receptor signaling and in neuronal cell differentiation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.