xRic-8 is a GEF for Gsalpha and participates in maintaining meiotic arrest in Xenopus laevis oocytes.
J Cell Physiol
; 214(3): 673-80, 2008 Mar.
Article
em En
| MEDLINE
| ID: mdl-17960561
ABSTRACT
Immature stage VI Xenopus oocytes are arrested at the G(2)/M border of meiosis I until exposed to progesterone, which induces meiotic resumption through a non-genomic mechanism. One of the earliest events produced by this hormone is inhibition of the plasma membrane enzyme adenylyl cyclase (AC), with the concomitant drop in intracellular cAMP levels and reinitiation of the cell cycle. Recently Gsalpha and Gbetagamma have been shown to play an important role as positive regulators of Xenopus oocyte AC, maintaining the oocyte in the arrested state. However, a question that still remains unanswered, is how the activated state of Gsalpha and Gbetagamma is achieved in the immature oocyte, since no receptor or ligand have been found to be required. Here we provide evidence that xRic-8 can act in vitro and in vivo as a GEF for Gsalpha. Overexpression of xRic-8, through mRNA injection, greatly inhibits progesterone induced oocyte maturation and endogenous xRic-8 mRNA depletion, through siRNA microinjection, induces spontaneous oocyte maturation. These results suggest that xRic-8 is participating in the immature oocyte by keeping Gsalpha-Gbetagamma-AC signaling complex in an activated state and therefore maintaining G2 arrest.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oócitos
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Xenopus laevis
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Subunidades alfa Gs de Proteínas de Ligação ao GTP
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Fatores de Troca do Nucleotídeo Guanina
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Proteínas de Xenopus
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Meiose
Limite:
Animals
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Humans
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article