Regulated Pumilio-2 binding controls RINGO/Spy mRNA translation and CPEB activation.
CPEB is a sequence-specific RNA-binding protein that controls the polyadenylation-induced translation of mos and cyclin B1 mRNAs in maturing Xenopus oocytes. CPEB activity requires not only the phosphorylation of S174, but also the synthesis of a heretofore-unknown upstream effector molecule. We show that the synthesis of RINGO/Spy, an atypical activator of cyclin-dependent kinases (cdks), is necessary for CPEB-directed polyadenylation. Deletion analysis and mRNA reporter assays show that a cis element in the RINGO/Spy 3'UTR is necessary for translational repression in immature (G2-arrested) oocytes. The repression is mediated by 3'UTR Pumilio-Binding Elements (PBEs), and by its binding protein Pumilio 2 (Pum2). Pum2 also interacts with the Xenopus homolog of human Deleted for Azoospermia-like (DAZL) and the embryonic poly(A)-binding protein (ePAB). Following the induction of maturation, Pum2 dissociates not only from RINGO/Spy mRNA, but from XDAZL and ePAB as well; as a consequence, RINGO/Spy mRNA is translated. These results demonstrate that a reversible Pum2 interaction controls RINGO/Spy mRNA translation and, as a result, CPEB-mediated cytoplasmic polyadenylation.
Padmanabhan
Kiran
K
Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
Richter
Joel D
JD
D020413:3' Untranslated Regions / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D039102:Poly(A)-Binding Proteins / Q000378:metabolism; D026723:Polyadenylation; D011374:Progesterone / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding / Q000235:genetics; D014176:Protein Biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D039221:mRNA Cleavage and Polyadenylation Factors
D020413:3' Untranslated Regions; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C490388:Cpeb1 protein, Xenopus; C503588:Dazl protein, Xenopus; C424905:PABPC4 protein, Xenopus; C430875:PUM1 protein, Xenopus; C471243:PUM2 protein, human; D039102:Poly(A)-Binding Proteins; C508296:Pum2 protein, Xenopus; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C119055:ls27 protein, Xenopus; D039221:mRNA Cleavage and Polyadenylation Factors; D011374:Progesterone