Characterization of the Drosophila Rae1 protein as a G1 phase regulator of the cell cycle.

Messengers RNA (mRNA) are thought to be export from the nucleus as ribonucleoprotein complexes (mRNP), whose exact protein composition remains not completely determined. The Gle2/RAE1 protein, a highly conserved member of the WD40 repeat protein family, was first shown to be involved in mRNA export. More recently, a role in the cell cycle was also suggested. To get new insights into the functions of the metazoan protein, the Drosophila melanogaster rae1 (dmrae1) cDNA was first cloned, then the corresponding protein characterized and its function investigated by RNA interference. This paper shows that dmRae1 mainly localises to the nuclear membrane like its homologue in Saccharomyces cerevisiae. However, unlike its homologue and despite this particular sub-cellular distribution, its depletion does not impair the export of polyA+ RNAs. Interestingly, the presence of dmRae1 is important for normal proliferation and, more importantly, for the progression through the G1 phase of the cell cycle. Given that dmRae1 is closely related to the human form, results suggest that the human homologue, hsRAE1, may also play a similar role during the cell cycle.