Abstract
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.
Publication types
-
Research Support, N.I.H., Extramural
MeSH terms
-
3' Untranslated Regions / genetics
-
3' Untranslated Regions / metabolism
-
Animals
-
Base Sequence
-
Carrier Proteins / metabolism
-
Cell Cycle Proteins / genetics
-
Cell Cycle Proteins / metabolism*
-
Gene Expression Regulation, Developmental
-
Humans
-
Models, Biological
-
Molecular Sequence Data
-
Oocytes / drug effects
-
Oocytes / enzymology
-
Oocytes / metabolism
-
Poly(A)-Binding Proteins / metabolism
-
Polyadenylation
-
Progesterone / metabolism
-
Progesterone / pharmacology
-
Protein Binding / genetics
-
Protein Biosynthesis / genetics*
-
RNA, Messenger / metabolism
-
RNA-Binding Proteins / immunology
-
RNA-Binding Proteins / metabolism*
-
Transcription Factors / metabolism*
-
Xenopus
-
Xenopus Proteins / genetics
-
Xenopus Proteins / metabolism*
-
mRNA Cleavage and Polyadenylation Factors
Substances
-
3' Untranslated Regions
-
Carrier Proteins
-
Cell Cycle Proteins
-
Cpeb1 protein, Xenopus
-
Dazl protein, Xenopus
-
PABPC4 protein, Xenopus
-
PUM1 protein, Xenopus
-
PUM2 protein, human
-
Poly(A)-Binding Proteins
-
Pum2 protein, Xenopus
-
RNA, Messenger
-
RNA-Binding Proteins
-
Transcription Factors
-
Xenopus Proteins
-
ls27 protein, Xenopus
-
mRNA Cleavage and Polyadenylation Factors
-
Progesterone