CPEB is a specificity factor that mediates cytoplasmic polyadenylation during Xenopus oocyte maturation

ABSTRACT Several cytoplasmic polyadenylation element (CPE)-containing mRNAs that are repressed in Xenopus oocytes become active during meiotic maturation. A group of factors that are anchored to the CPE are responsible for this repression and activation. Two of the most important are CPEB, which binds directly to the CPE, and Maskin, which associates with CPEB. In oocytes, Maskin also binds eukaryotic translation initiation factor 4E (eIF4E), an interaction that excludes eIF4G and prevents formation of the eIF4F initiation complex. When the oocytes are stimulated to reenter the meiotic divisions (maturation), CPEB promotes cytoplasmic polyadenylation. The newly elongated poly(A) tail becomes bound by poly(A) binding protein (PABP), which in turn binds eIF4G and helps it displace Maskin from eIF4E, thereby inducing translation. Here we show that Maskin undergoes several phosphorylation events during oocyte maturation, some of which are important for its dissociation from eIF4E and translational activation of CPE-containing mRNA. These sites are T58, S152, S311, S343, S453, and S638 and are phosphorylated by cdk1. Mutation of these sites to alanine alleviates the cdk1-induced dissociation of Maskin from eIF4E. Prior to maturation, Maskin is phosphorylated on S626 by protein kinase A. While this modification has no detectable effect on translation during oocyte maturation, it is critical for this protein to localize on the mitotic apparatus in somatic cells. These results show that Maskin activity and localization is controlled by differential phosphorylation.

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Actin assembly mediated by a nucleation promoting factor WASH is involved in MTOC–TMA formation during Xenopus oocyte maturation

Cytoskeleton ◽

10.1002/cm.21428 ◽

2018 ◽

Vol 75 (3) ◽

pp. 131-143 ◽

Cited By ~ 4

Author(s):

Yuka Yamagishi ◽

Hiroshi Abe

Keyword(s):

Oocyte Maturation ◽

Xenopus Oocyte ◽

Actin Assembly ◽

Nucleation Promoting Factor

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c-Mos and cyclin B/cdc2 connections during Xenopus oocyte maturation

Biology of the Cell ◽

10.1016/s0248-4900(01)01128-5 ◽

2001 ◽

Vol 93 (1-2) ◽

pp. 15-25 ◽

Cited By ~ 17

Author(s):

Anna Castro ◽

Marion Peter ◽

Thierry Lorca ◽

Elisabeth Mandart

Keyword(s):

Oocyte Maturation ◽

Xenopus Oocyte ◽

Cyclin B

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Regulation of Src kinase activity during Xenopus oocyte maturation

Developmental Biology ◽

10.1016/j.ydbio.2004.10.018 ◽

2005 ◽

Vol 278 (2) ◽

pp. 289-300 ◽

Cited By ~ 20

Author(s):

Alexander Tokmakov ◽

Tetsushi Iwasaki ◽

Shuji Itakura ◽

Ken-Ichi Sato ◽

Mikako Shirouzu ◽

...

Keyword(s):

Oocyte Maturation ◽

Xenopus Oocyte ◽

Kinase Activity ◽

Src Kinase

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The Cleavage and Polyadenylation Specificity Factor in Xenopus laevis Oocytes Is a Cytoplasmic Factor Involved in Regulated Polyadenylation

Molecular and Cellular Biology ◽

10.1128/mcb.19.8.5707 ◽

1999 ◽

Vol 19 (8) ◽

pp. 5707-5717 ◽

Cited By ~ 55

Author(s):

Kirsten S. Dickson ◽

Andrea Bilger ◽

Scott Ballantyne ◽

Marvin P. Wickens

Keyword(s):

Xenopus Laevis ◽

Bos Taurus ◽

Xenopus Laevis Oocytes ◽

Ns1 Protein ◽

Amino Acid Sequence Level ◽

Cytoplasmic Factor ◽

Cytoplasmic Polyadenylation ◽

Cleavage And Polyadenylation ◽

Specificity Factor

ABSTRACT During early development, specific mRNAs receive poly(A) in the cytoplasm. This cytoplasmic polyadenylation reaction correlates with, and in some cases causes, translational stimulation. Previously, it was suggested that a factor similar to the multisubunit nuclear cleavage and polyadenylation specificity factor (CPSF) played a role in cytoplasmic polyadenylation. A cDNA encoding a cytoplasmic form of the 100-kDa subunit of Xenopus laevis CPSF has now been isolated. The protein product is 91% identical at the amino acid sequence level to nuclear CPSF isolated from Bos taurusthymus. This report provides three lines of evidence that implicate theX. laevis homologue of the 100-kDa subunit of CPSF in the cytoplasmic polyadenylation reaction. First, the protein is predominantly localized to the cytoplasm of X. laevisoocytes. Second, the 100-kDa subunit of X. laevis CPSF forms a specific complex with RNAs that contain both a cytoplasmic polyadenylation element (CPE) and the polyadenylation element AAUAAA. Third, immunodepletion of the 100-kDa subunit ofX. laevis CPSF reduces CPE-specific polyadenylation in vitro. Further support for a cytoplasmic form of CPSF comes from evidence that a putative homologue of the 30-kDa subunit of nuclear CPSF is also localized to the cytoplasm of X. laevisoocytes. Overexpression of influenza virus NS1 protein, which inhibits nuclear polyadenylation through an interaction with the 30-kDa subunit of nuclear CPSF, prevents cytoplasmic polyadenylation, suggesting that the cytoplasmic X. laevis form of the 30-kDa subunit of CPSF is involved in this reaction. Together, these results indicate that a distinct, cytoplasmic form of CPSF is an integral component of the cytoplasmic polyadenylation machinery.

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In vitro facilitation of Xenopus oocyte maturation by subthreshold doses of progesterone

Developmental Biology ◽

10.1016/0012-1606(77)90243-3 ◽

1977 ◽

Vol 59 (1) ◽

pp. 91-95 ◽

Cited By ~ 21

Author(s):

Jean Marot ◽

Robert Bellé ◽

René Ozon

Keyword(s):

Oocyte Maturation ◽

Xenopus Oocyte

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Maturation-specific polyadenylation and translational control: diversity of cytoplasmic polyadenylation elements, influence of poly(A) tail size, and formation of stable polyadenylation complexes.

Molecular and Cellular Biology ◽

10.1128/mcb.10.11.5634 ◽

1990 ◽

Vol 10 (11) ◽

pp. 5634-5645 ◽

Cited By ~ 91

Author(s):

J Paris ◽

J D Richter

Keyword(s):

Complex Formation ◽

Oocyte Maturation ◽

Translational Control ◽

Untranslated Regions ◽

Stable Complex ◽

Mobility Shift ◽

Cytoplasmic Polyadenylation ◽

Egg Extracts ◽

Gel Mobility Shift ◽

Rna Polyadenylation

Early embryonic development in Xenopus laevis is programmed in part by maternally derived mRNAs, many of which are translated at the completion of meiosis (oocyte maturation). Polysomal recruitment of at least one of these mRNAs, G10, is regulated by cytoplasmic poly(A) elongation which, in turn, is dependent upon the cytoplasmic polyadenylation element (CPE) UUUUUUAUAAAG and the hexanucleotide AAUAAA (L. L. McGrew, E. Dworkin-Rastl, M. B. Dworkin, and J. D. Richter, Genes Dev. 3:803-815, 1989). We have investigated whether sequences similar to the G10 RNA CPE that are present in other RNAs could also be responsible for maturation-specific polyadenylation. B4 RNA, which encodes a histone H1-like protein, requires a CPE of the sequence UUUUUAAU as well as the polyadenylation hexanucleotide. The 3' untranslated regions of Xenopus c-mos RNA and mouse HPRT RNA also contain U-rich CPEs since they confer maturation-specific polyadenylation when fused to Xenopus B-globin RNA. Polyadenylation of B4 RNA, which occurs very early during maturation, is limited to 150 residues, and it is this number that is required for polysomal recruitment. To investigate the possible diversity of factors and/or affinities that might control polyadenylation, egg extracts that faithfully adenylate exogenously added RNA were used in competition experiments. At least one factor is shared by B4 and G10 RNAs, although it has a much greater affinity for B4 RNA. Additional experiments demonstrate that an intact CPE and hexanucleotide are both required to compete for the polyadenylation apparatus. Gel mobility shift assays show that two polyadenylation complexes are formed on B4 RNA. Optimal complex formation requires an intact CPE and hexanucleotide but not ongoing adenylation. These data, plus additional RNA competition studies, suggest that stable complex formation is enhanced by an interaction of the trans-acting factors that bind the CPE and polyadenylation hexanucleotide.

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