Biochemical Characterization of Pumilio1 and Pumilio2 in Xenopus Oocytes

• Published in: The Journal of biological chemistry Vol. 286; no. 4; pp. 2853 - 2863
• Main Authors: Ota, Ryoma, Kotani, Tomoya, Yamashita, Masakane
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28-01-2011; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Antibodies - chemistry; Base Sequence; Carrier Proteins - biosynthesis; Carrier Proteins - genetics; Cell Cycle Proteins - biosynthesis; Cell Cycle Proteins - genetics; Cyclin B1 - biosynthesis; Cyclin B1 - genetics; Cyclins; Gene Regulation; Molecular Sequence Data; mRNA; mRNA Cleavage and Polyadenylation Factors - biosynthesis; mRNA Cleavage and Polyadenylation Factors - genetics; Oocyte; Oocytes - metabolism; Phosphorylation - physiology; Protein Biosynthesis - physiology; Protein-Protein Interactions; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA-binding Protein; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; Time Factors; Transcription Factors - biosynthesis; Transcription Factors - genetics; Translation Control; Xenopus; Xenopus laevis; Xenopus Proteins - biosynthesis; Xenopus Proteins - genetics; Xenopus Proteins - metabolism; Xenopus; mRNA; RNA-binding Protein; Translation Control; Cyclins; Oocyte; Protein-Protein Interactions
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.155523

Precise control of the timing of translational activation of dormant mRNAs stored in oocytes is required for normal progression of oocyte maturation. We previously showed that Pumilio1 (Pum1) is specifically involved in the translational control of cyclin B1 mRNA during Xenopus oocyte maturation, in cooperation with cytoplasmic polyadenylation element-binding protein (CPEB). It was reported that another Pumilio, Pumilio2 (Pum2), exists in Xenopus oocytes and that this protein regulates the translation of RINGO mRNA, together with Deleted in Azoospermia-like protein (DAZL). In this study, we characterized Pum1 and Pum2 biochemically by using newly produced antibodies that discriminate between them. Pum1 and Pum2 are bound to several key proteins involved in translational control of dormant mRNAs, including CPEB and DAZL, in immature oocytes. However, Pum1 and Pum2 themselves have no physical interaction. Injection of anti-Pum1 or anti-Pum2 antibody accelerated CPEB phosphorylation, cyclin B1 translation, and oocyte maturation. Pum1 phosphorylation coincides with the dissociation of CPEB from Pum1 and the translational activation of cyclin B1 mRNA, a target of Pum1, whereas Pum2 phosphorylation occurred at timing earlier than that for Pum1. Some, but not all, of cyclin B1 mRNAs release the deadenylase PARN during oocyte maturation, whereas Pum1 remains associated with the mRNA. On the basis of these findings, we discuss the functions of Pum1 and Pum2 in translational control of mRNAs during oocyte maturation.