Two otu transcripts are selectively localised in Drosophila oogenesis by a mechanism that requires a function of the otu protein

Abstract

The ovarian tumour gene (otu) is required for several processes during Drosophila oogenesis. The locus encodes two protein isoforms that have been proposed to act during different stages of oogenesis. Here we show that the corresponding otu mRNAs display a dynamic pattern of expression during oogenesis. The 4.1 kb mRNA encoding the 104 kDa isoform is expressed throughout adult oogenesis, but is mainly restricted to nurse cells. The 3.2 kb mRNA encoding the 98 kDa protein isoform is selectively localised in the oocyte up to stage 9. Both mRNAs are expressed abundantly in nurse cells at stages 10-11. We propose that the oocyte-specific function of otu is realised by the 98 kDa isoform. We show that the export of the 3.2 kb mRNA from the nurse cell nuclei requires a functional otu protein. The otu protein is also required for the correct distribution of the pumilio and oskar mRNAs, while the Bic-D, K10 and staufen mRNAs are localised in wild type fashion in otu mutants. Furthermore, we have observed a region of homology between the carboxy-terminal part of the otu protein and the mammalian microtubule associated proteins. The more severe the mutation in this region of homology, the more disturbed mRNA distribution is observed in otu mutants.

Hrb27C, Sqd and Otu cooperatively regulategurkenRNA localization and mediate nurse cell chromosome dispersion inDrosophilaoogenesis

“…Interestingly, the otu 11 allele, which contains a missense mutation in exon 6a (Steinhauer and Kalfayan, 1992), shows the grk localization and dorsalization defect, strongly suggesting that the tudor domain of Otu plays an important function in grk localization. As otu mutants also show defects in osk localization (Tirronen et al, 1995), it appears that like several other factors, Otu is required for both grk and osk localization. Additionally, Otu has been isolated from cytoplasmic mRNP complexes (Glenn and Searles, 2001).…”

“…otu produces two protein isoforms, Otu98 and Otu104, by alternative splicing of a 126 bp exon. Genetic and molecular analyses reveal distinct requirements for each isoform during oogenesis Steinhauer and Kalfayan, 1992;Sass et al, 1995;Tirronen et al, 1995). In particular, a mutant that specifically disrupts the Otu104 product has persistent polytene nurse cell chromosomes, suggesting that the 98 kDa Otu isoform is not capable of mediating wild-type chromosome dispersion (Steinhauer and Kalfayan, 1992).…”

Rna Localization in Development

“…For example, nanos is transcribed at low levels, and oocyte accumulation can be seen only later (28). Additional transcripts, such as ovarian tumor (29) and cytoplasmic tropomyosin II (cTmII ) (30), also accumulate in the oocyte at this and later stages but are not localized. Therefore oocyte-specific accumulation is not unique to RNAs that will be localized within the oocyte during later stages of oogenesis but is a property of many RNAs synthesized in the germline of early egg chambers.…”

Localization, anchoring and translational control ofoskar,gurken,bicoidandnanosmRNA during Drosophila oogenesis

“…24,27 Consistent with the idea that association of Otu and Glo with Hrp48 promotes posterior osk mRNA localization, oocytes mutant for otu or glo display defects in posterior osk mRNA deployment. 27,28 Another RNA associated protein which functions in posterior osk mRNA localization is the decapping protein dDcp1. 29 dDcp1 localizes to the posterior of the oocyte in a osk mRNA-and MT-dependent manner, but it is itself required for posterior osk mRNA localization as osk mRNA is frequently mislocalized to the anterior in hypo-called tsunagi) and eIF4AIII have all been implicated in posterior osk localization.…”