| Texto completo | |
| Autor(es): |
Milograna, Sarah Ribeiro
;
Ribeiro, Marcia Regina
;
Bell, Fernanda Tinti
;
McNamara, John Campbell
Número total de Autores: 4
|
| Tipo de documento: | Artigo Científico |
| Fonte: | JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL GENETICS AND PHYSIOLOGY; v. 325, n. 9, p. 565-580, NOV 2016. |
| Citações Web of Science: | 3 |
| Resumo | |
Pigment aggregation in shrimp chromatophores is triggered by red pigment concentrating hormone (RPCH), a neurosecretory peptide whose plasma membrane receptor may be a G-protein coupled receptor (GPCR). While RPCH binding activates the Ca2+/cGMP signaling cascades, a role for cyclic AMP (cAMP) in pigment aggregation is obscure, as are the steps governing Ca2+ release from the smooth endoplasmic reticulum (SER). A role for the antagonistic neuropeptide, pigment dispersing homone (-PDH) is also unclear. In red, ovarian chromatophores from the freshwater shrimp Macrobrachium olfersi, we show that a G-protein antagonist (AntPG) strongly inhibits RPCH-triggered pigment aggregation, suggesting that RPCH binds to a GPCR, activating an inhibitory G-protein. Decreasing cAMP levels may cue pigment aggregation, since cytosolic cAMP titers, when augmented by cholera toxin, forskolin or vinpocentine, completely or partially impair pigment aggregation. Triggering opposing Ca2+/cGMP and cAMP cascades by simultaneous perfusion with lipid-soluble cyclic nucleotide analogs induces a tug-of-war response, pigments aggregating in some chromatosomes with unpredictable, oscillatory movements in others. Inhibition of cAMP-dependent protein kinase accelerates aggregation and reduces dispersion velocities, suggesting a role in phosphorylation events, possibly regulating SER Ca2+ release and pigment aggregation. The second messengers IP3 and cADPR do not stimulate SER Ca2+ release. -PDH does not sustain pigment dispersion, suggesting that pigment translocation in caridean chromatophores may be regulated solely by RPCH, since PDH is not required. We propose a working hypothesis to further unravel key steps in the mechanisms of pigment translocation within crustacean chromatophores that have remained obscure for nearly a century. (AU) | |
| Processo FAPESP: | 00/04588-2 - Um estudo da transducao de sinal e do mecanismo de translocacao pigmentar nos cromatossomos ovarianos do camarao macrobrachium olfersii (crustacea, decapoda). |
| Beneficiário: | John Campbell McNamara |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 08/52647-0 - Translocacao pigmentar em cromatoforos ovarianos do camarao de agua-doce macrobrachium olfersi (crustacea, decapoda): do receptor aos motores moleculares. |
| Beneficiário: | Sarah Ribeiro Milograna |
| Modalidade de apoio: | Bolsas no Brasil - Mestrado |