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α‐MSH and Desacetyl‐α‐MSH Signaling through Melanocortin Receptors
Author(s) -
MOUNTJOY KATHLEEN G.,
WU CHIASHAN JENNY,
CORNISH JILLIAN,
CALLON KAREN E.
Publication year - 2003
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2003.tb03162.x
Subject(s) - melanocortin , receptor , endocrinology , melanocortin receptor , medicine , adenylyl cyclase , signal transduction , chemistry , alpha (finance) , melanocortins , biology , biochemistry , construct validity , nursing , patient satisfaction
A bstract : The functional significance of N‐terminal acetylation of ACTH[1–13]NH 2 is unknown. N‐terminal acetylation of ACTH[1–13]NH 2 (known as desacetyl‐α‐MSH) to produce α‐MSH enhances some activities of ACTH[1–13]NH 2 and virtually eliminates others. To determine whether α‐MSH and desacetyl‐α‐MSH diverge in their coupling to melanocortin receptors in vitro , we measured the sensitivity of MC1, MC3, MC4, and MC5 receptors stably expressed in HEK293 cells to these peptides, functionally coupling them to adenylyl cyclase and a calcium signaling pathway. α‐MSH and desacetyl‐α‐MSH similarly coupled these overexpressed receptors to both signaling pathways. In contrast, we discovered that α‐MSH significantly increased primary rat osteoblast proliferation while for desacetyl‐α‐MSH there was only a trend to do the same. Osteoblast cells expressing very low levels of endogenous melanocortin receptors, in contrast with transfected HEK293 cells overexpressing a single melanocortin receptor, may provide an in vitro model for differentiating between α‐MSH and desacetyl‐α‐MSH signaling.