Possible role of mouse poly(A) polymerase mGLD-2 during oocyte maturation.
Cytoplasmic polyadenylation of mRNAs is involved in post-transcriptional regulation of genes, including translational activation. In addition to yeast Cid1 and Cid13 and mouse TPAP, GLD-2 has been recently identified as a cytoplasmic poly(A) polymerase in Caenorhabditis elegans and Xenopus oocytes. In this study, we have characterized mouse GLD-2, mGLD-2, in adult tissues, meiotically maturing oocytes, and NIH3T3 cultured cells. mGLD-2 was ubiquitously present in all tissues and cells tested. mGLD-2 was localized in the nucleus as well as in the cytoplasm of somatic, testicular, and cultured cells. Transfection of expression plasmids encoding mGLD-2 and the mutant proteins into NIH3T3 cells revealed that a 17-residue sequence in the N-terminal region of mGLD-2 probably acts as a localization signal required for the transport into the nucleus. Analysis of reverse transcriptase-polymerase chain reaction indicated the presence of mGLD-2 mRNA in the oocytes throughout meiotic maturation. However, 54-kDa mGLD-2 was found in the oocytes only at the metaphases I and II after germinal vesicle breakdown, presumably due to translational control. When mGLD-2 synthesis was artificially inhibited and enhanced by injection of double-stranded and polyadenylated RNAs into the germinal vesicle-stage oocytes, respectively, oocyte maturation was significantly arrested at the metaphase-I stage. These results suggest that mGLD-2 may act in the ooplasm on the progression of metaphase I to metaphase II during oocyte maturation.
Nakanishi
Tomoko
T
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki, Japan.
Kubota
Haruka
H
Ishibashi
Naoko
N
Kumagai
Satoshi
S
Watanabe
Hiromi
H
Yamashita
Misuzu
M
Kashiwabara
Shin-Ichi
S
Miyado
Kenji
K
Baba
Tadashi
T
D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology; D003593:Cytoplasm / Q000201:enzymology; D005260:Female; D008297:Male; D008677:Metaphase / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009865:Oocytes / Q000201:enzymology* / Q000254:growth & development*; D011062:Polynucleotide Adenylyltransferase / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D013737:Testis / Q000201:enzymology; D014018:Tissue Distribution
D012333:RNA, Messenger; D011062:Polynucleotide Adenylyltransferase