Elsevier

Developmental Biology

Volume 297, Issue 2, 15 September 2006, Pages 350-360
Developmental Biology

Stage-specific Importin13 activity influences meiosis of germ cells in the mouse

https://doi.org/10.1016/j.ydbio.2006.04.465Get rights and content
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Abstract

Importin-mediated transport of cargoes is known to be a key mechanism for nucleo-cytoplasmic trafficking of molecules. Ipo13, which is a member of Importin-β gene family, encodes two transcripts by utilizing different transcription start sites. In the mouse, the full-length transcript (L-Ipo13) is expressed in the primordial germ cells in the embryo and is later expressed predominantly at the pachytene phase of meiosis in both male and female germ cells. The shorter transcript (TS-Ipo13) is only expressed in the germ cells in the adult testis. Activity of L-Ipo13, but not TS-Ipo13, mediates the nuclear accumulation of ubiquitin-conjugating enzyme 9 (UBC9), a cargo of human IPO13. This finding is consistent with the progressive accumulation of UBC9 in the nucleus of the meiotic germ cells after the onset of L-Ipo13 expression. Following siRNA knockdown of IPO13 activity in the fetal ovary, fewer germ cells are found to progress to the late-pachytene stage of meiosis and nuclear accumulation of UBC9 is reduced. Our findings strongly implicate a stage-specific role of IPO13 in nuclear-cytoplasmic translocation of cargoes that accompanies meiotic differentiation of the mouse germ cells.

Keywords

Importin13
Primordial germ cells
Germ cells
Meiosis
UBC9
Pachytene

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1

Present address: Division of Integrative Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811, Japan.