Pigment Translocation in Caridean Shrimp Chromatophores: Receptor Type, Signal Transduction, Second Messengers, and Cross Talk Among Multiple Signaling Cascades

Autor(es)

Milograna, Sarah Ribeiro ; Ribeiro, Marcia Regina ; Bell, Fernanda Tinti ; McNamara, John Campbell

• 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 transdução de sinal e do mecanismo de translocação pigmentar nos cromatossomos ovarianos do camarão Macrobrachium olfersii (Crustacea, Decapoda)
• Beneficiário: John Campbell McNamara
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 08/52647-0 - Translocação pigmentar em cromatóforos ovarianos do camarão de água-doce Macrobrachium olfersi (Crustacea, Decapoda): do receptor aos motores moleculares
• Beneficiário: Sarah Ribeiro Milograna
• Modalidade de apoio: Bolsas no Brasil - Mestrado