Differential expression of nucleoside diphosphate kinases (NDPK/NM23) during Xenopus early development.
In Xenopus laevis, three nucleoside diphosphate kinase (NDPK) monomers have been described (NDPK X1, X2 and X3) (Ouatas et al., 1997). In eucaryotes, this kinase is known as a hetero- or homohexamer. Here, we examine the distribution of the enzyme and its different subunit mRNAs during oogenesis and early embryogenesis of Xenopus laevis, respectively by immunohistofluorescence and whole-mount in situ hybridization. These analyses show that NDPKs and their mRNAs are differentially distributed throughout the oocyte and early embryos with a high level of transcription in somites and brain. We emphasize two points. First, each mRNA displays a distinct subcellular localization in somites, suggesting a complex regulation of NDPK genes both at the transcriptional and translational level and a possible involvement of NDPK X2 homohexamers in the dorsal muscle differentiation. Second, in oocytes and early embryos, the proteins are mainly localized in the nucleus, suggesting a new mechanism for their nuclear import, since they do not possess any known nuclear import sequences.
Ouatas
T
T
Centre de Génétique Moléculaire, CNRS, Gif-sur-Yvette, France. ouatas@mnhn.fr
Sélo
M
M
Sadji
Z
Z
Hourdry
J
J
Denis
H
H
Mazabraud
A
A
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020559:Monomeric GTP-Binding Proteins; D054778:NM23 Nucleoside Diphosphate Kinases; D009687:Nuclear Proteins / Q000378:metabolism; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics; D014981:Xenopus / Q000196:embryology*
D054778:NM23 Nucleoside Diphosphate Kinases; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D009701:Nucleoside-Diphosphate Kinase; D020559:Monomeric GTP-Binding Proteins