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Metadados | Descrição | Idioma |
---|---|---|
Autor(es): dc.creator | Isoldi, Mauro César | - |
Autor(es): dc.creator | Provencio, Ignacio | - |
Autor(es): dc.creator | Castrucci, Ana Maria de Lauro | - |
Data de aceite: dc.date.accessioned | 2019-11-06T13:32:36Z | - |
Data de disponibilização: dc.date.available | 2019-11-06T13:32:36Z | - |
Data de envio: dc.date.issued | 2015-03-06 | - |
Data de envio: dc.date.issued | 2015-03-06 | - |
Data de envio: dc.date.issued | 2010 | - |
Fonte completa do material: dc.identifier | http://www.repositorio.ufop.br/handle/123456789/4554 | - |
Fonte: dc.identifier.uri | http://educapes.capes.gov.br/handle/capes/557662 | - |
Descrição: dc.description | Melanin granule (melanosome) dispersion within Xenopus laevis melanophores is evoked either by light or a-MSH. We have previously demonstrated that the initial biochemical steps of light and a-MSH signaling are distinct, since the increase in cAMP observed in response to a-MSH was not seen after light exposure. cAMP concentrations in response to a-MSH were significantly lower in cells pre-exposed to light as compared to the levels in dark-adapted melanophores. Here we demonstrate the presence of an adenylyl cyclase (AC) in the Xenopus melanophore, similar to the mammalian type IX which is inhibited by Ca2+–calmodulin-activated phosphatase. This finding supports the hypothesis that the cyclase could be negatively modulated by a light-promoted Ca2+ increase. In fact, the activity of calcineurin PP2B phosphatase was increased by light, which could result in AC IX inhibition, thus decreasing the response to a-MSH. St-Ht31, a disrupting agent of protein kinase A (PKA)–anchoring kinase A protein (AKAP) complex totally blocked the melanosome dispersing response to a-MSH, but did not impair the photo-response in Xenopus melanophores. Sequence comparison of a melanophore AKAP partial clone with GenBank sequences showed that the anchoring protein was a gravin-like adaptor previously sequenced from Xenopus non-pigmentary tissues. Co-immunoprecipitation of Xenopus AKAP and the catalytic subunit of PKA demonstrated that PKA is associated with AKAP and it is released in the presence of a-MSH. We conclude that in X. laevis melanophores, AKAP12 (gravin-like) contains a site for binding the inactive PKA thus compartmentalizing PKA signaling and also possesses binding sites for PKC. Light diminishes a-MSH-induced increase of cAMP by increasing calcineurin (PP2B) activity, which in turn inhibits adenylyl cyclase type IX, and/or by activating PKC, which phosphorylates the gravin-like molecule, thus destabilizing its binding to the cell membrane. | - |
Idioma: dc.language | en | - |
Direitos: dc.rights | O Periódico General and Comparative Endocrinology concede permissão para depósito deste artigo no Repositório Institucional da UFOP. Número da licença: 3546550247482. | - |
Palavras-chave: dc.subject | Melanophore | - |
Palavras-chave: dc.subject | Melanopsin | - |
Palavras-chave: dc.subject | Light | - |
Palavras-chave: dc.subject | Calcineurin | - |
Palavras-chave: dc.subject | Melanosome photo-dispersion | - |
Título: dc.title | Light modulates the melanophore response to a-MSH in Xenopus laevis: an analysis of the signal transduction crosstalk mechanisms involved. | - |
Aparece nas coleções: | Repositório Institucional - UFOP |
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