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Unformatted text preview: play a role in regulating weight. Agouti is usually expressed only in the skin, and mice
homozygous for null mutations of agouti, such as extreme nonagouti
(ae), do not display abnormalities of weight regulation. Controllo del colore del mantello nel topo a
Mc1r a-MSH Melanocyte
pigment Dermal papilla b An agouti-related gene involved in weight regulation Figure 2. The Agouti signaling pathway. (a) Melanocyte pigment production
is regulated by agouti and -melanocyte stimulating hormone ( -MSH). The
paracrine signaling molecule agouti is produced by dermal papillae in the
skin. Agouti binds to, and inhibits signaling through, the melanocortin-1 receptor (Mc1r), a G protein-coupled receptor present on the surface of
melanocytes in overlying hair follicles. The resulting decreased Mc1r signaling induces melanocytes to synthesize the yellow/red pigment, pheomelanin. In contrast, the endocrine signaling molecule -MSH, produced and
secreted by the intermediate pituitary (pars intermedia), binds to Mc1r and
activates signaling, and this increased Mc1r signaling stimulates follicular
melanocytes to synthesize the black pigment, eumelanin. (b) The classic
agouti coat color, which app...
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This document was uploaded on 04/02/2014.
- Fall '14