An interaction network of RNA-binding proteins involved in Drosophila oogenesis

Prashali Bansal; Johannes Madlung; Kristina Schaaf; Boris Macek; Fulvia Bono

In addition to their crucial role in pre-mRNA processing, splicing factors also affect the cytoplasmic fates of mRNAs. SmB, a spliceomosomal Sm protein is a known osk mRNP component. SmB contributes to germcell specification, at least in part by facilitating osk mRNA localization (103) and fails to localize to the posterior of the oocyte in the absence of Vas (104) . Several Sm proteins have also been detected to be associated with Vas in the oocytes (56). Consistent with this, we co-purified SmB with Stau, Glo, Hrp48 and Vas. We also purified other splicing regulators with several of our baits, including pUF68 (105) and the SR family proteins SC35 and SF2 (106, 107) . Both SC35 and SF2 could be validated for their interaction with Glo and Stau, while pUF68 bound eIF4AIII and Stau in vitro. pUF68 was previously shown to interact with Hrp48 and Glo (38) and SF2 co-purifies with the short isoform of Osk (108) . These results together with the well-studied role of SR proteins in cytoplasmic regulation of gene expression including mRNA export, decay and translation in mammalian systems (109, 110) suggest that splicing factors are bona fide components of the mRNA localization machinery.