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Melanocortin potentiates leptin‐induced STAT3 signaling via MAPK pathway
Author(s) -
Zhang Yan,
Wu Xiaojun,
He Yi,
Kastin Abba J.,
Hsuchou Hung,
Rosenblum Charles I.,
Pan Weihong
Publication year - 2009
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2009.06144.x
Subject(s) - leptin , melanocortin , medicine , endocrinology , mapk/erk pathway , signal transduction , biology , melanocortin 4 receptor , receptor , protein kinase a , leptin receptor , microbiology and biotechnology , stat3 , kinase , hormone , obesity
Abstract The co‐existence of receptors for leptin and melanocortin in cerebral microvessels suggests possible interactions between leptin and α‐melanocyte stimulating hormone (MSH) signaling. In this study, we showed that ObRb and melanocortin receptor MC3R and MC4R were present in enriched cerebral microvessels. To test the interactions between ObRb and MC3R or MC4R‐mediated cellular signaling, we over‐expressed these plasmids in RBE4 cerebral microvascular endothelial cells and HEK293 cells in culture. Activation of signal transducers and activators of transcription‐3 (STAT3) in response to leptin was determined by western blotting and luciferase reporter assays. Production of cAMP downstream to melanocortin receptors was determined with a chemiluminescent ELISA kit. αMSH, which increased intracellular cAMP, also potentiated leptin‐induced STAT3 activation. This potentiation was abolished by a specific MEK inhibitor, indicating the involvement of the mitogen‐activated kinase pathway. Reversely, the effect of leptin on αMSH‐induced cAMP production was minimal. Thus, melanocortin specifically potentiated STAT3 signaling downstream to ObRb by cross‐talk with mitogen‐activated kinase. The cooperation of ObRb and G protein‐coupled receptors in cellular signaling may have considerable biological implications not restricted to feeding and obesity.