title: The amphibian melanization inhibiting factor (MIF) blocks the alpha-MSH effect on mouse malignant melanocytes.
abstract: We have found that a melanization inhibitory factor (MIF) extracted from the ventral skin of Rana forreri has a slight inhibitory effect on the activity levels of tyrosinase and dopachrome tautomerase in B16/F10 and Cloudman S-91 murine melanoma cell lines. Furthermore, this factor appears to block the effects of alpha-MSH on these enzymatic activities. However, MIF treatment does not affect the melanogenic action of theophylline on the same cells, suggesting that MIF acts proximal to MSH-mediated cAMP formation, possibly by interaction with the MSH receptor. In this way, we show that this amphibian factor has biological activity on mammalian melanocytes. This suggests the existence of mammalian counterparts of amphibian MIF in the mouse integument that might regulate epidermal melanocytes. These peptides might be related to the agouti protein, as they share similar mechanisms of action. The interaction of different peptides with the MSH receptor would be a complex but general mechanism responsible for many mammalian coat color variants.
authors.affiliation: Departamento de Bioquímica y Biología Molecular e Immunología, Facultad de Medicina, Universidad de Murcia, Spain.
authors.forename: A M
authors.initials: AM
authors.lastname: López-Contreras
authors.forename: J H
authors.initials: JH
authors.lastname: Martínez-Liarte
authors.forename: F
authors.initials: F
authors.lastname: Solano
authors.forename: P
authors.initials: P
authors.lastname: Samaraweera
authors.forename: J M
authors.initials: JM
authors.lastname: Newton
authors.forename: J T
authors.initials: JT
authors.lastname: Bagnara
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D019746:Intramolecular Oxidoreductases; D007535:Isomerases / Q000187:drug effects / Q000378:metabolism; D009075:MSH Release-Inhibiting Hormone / Q000494:pharmacology*; D008543:Melanins / Q000737:chemistry / Q000378:metabolism*; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D014442:Monophenol Monooxygenase / Q000187:drug effects / Q000378:metabolism; D011898:Ranidae; D013806:Theophylline / Q000494:pharmacology; D014446:Tyrosine 3-Monooxygenase / Q000187:drug effects / Q000378:metabolism; D014665:Vasodilator Agents / Q000494:pharmacology; D000521:alpha-MSH / Q000494:pharmacology*
chemical_list: D008543:Melanins; D014665:Vasodilator Agents; D000521:alpha-MSH; D009075:MSH Release-Inhibiting Hormone; D013806:Theophylline; D014446:Tyrosine 3-Monooxygenase; D014442:Monophenol Monooxygenase; D007535:Isomerases; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase