Progesterone regulates the accumulation and the activation of Eg2 kinase in Xenopus oocytes

• Published in: Journal of cell science Vol. 113 ( Pt 7); no. 7; pp. 1127 - 1138
• Main Authors: Frank-Vaillant, M, Haccard, O, Thibier, C, Ozon, R, Arlot-Bonnemains, Y, Prigent, C, Jessus, C
• Format: Journal Article
• Language: English
• Published: England Company of Biologists 01.04.2000
• Subjects: Animals; Aurora Kinases; CDC2 Protein Kinase - metabolism; CDC2 Protein Kinase - physiology; Cell Cycle Proteins - metabolism; Cell Differentiation; Cyclic AMP-Dependent Protein Kinases - metabolism; Enzyme Activation; Female; Freshwater; Life Sciences; Meiosis; Oocytes - enzymology; Oocytes - metabolism; Oocytes - physiology; Parthenogenesis; Phosphorylation; Poly A - metabolism; Progesterone - physiology; Protein Kinases - metabolism; Protein Serine-Threonine Kinases; Ribose - metabolism; RNA Caps - metabolism; RNA, Messenger - metabolism; Xenopus; Xenopus laevis; Xenopus Proteins
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.113.7.1127

Xenopus prophase oocytes reenter meiotic division in response to progesterone. The signaling pathway leading to Cdc2 activation depends on neosynthesized proteins and a decrease in PKA activity. We demonstrate that Eg2 protein, a Xenopus member of the Aurora/Ipl1 family of protein kinases, accumulates in response to progesterone and is degraded after parthenogenetic activation. The polyadenylation and cap ribose methylation of Eg2 mRNA are not needed for the protein accumulation. Eg2 protein accumulation is induced by progesterone through a decrease in PKA activity, upstream of Cdc2 activation. Eg2 kinase activity is undetectable in prophase and is raised in parallel with Cdc2 activation. In contrast to Eg2 protein accumulation, Eg2 kinase activation is under Cdc2 control. Furthermore, by using an anti-sense strategy, we show that Eg2 accumulation is not required in the transduction pathway leading to Cdc2 activation. Altogether, our results strongly suggest that Eg2 is not necessary for Cdc2 activation, though it could participate in the organization of the meiotic spindles, in agreement with the well-conserved roles of the members of the Aurora family, from yeast to man.