Homeless is required for RNA localization in Drosophila oogenesis and encodes a new member of the DE-H family of RNA-dependent ATPases.

Abstract

The homeless (hls) gene of Drosophila is required for anteroposterior and dorsoventral axis formation during oogenesis. At a low frequency, females homozygous for mutations in hls generate early egg chambers in which the oocyte is positioned incorrectly within the cyst. At a high frequency, late-stage egg chambers exhibit a ventralized chorion. Sequence analysis of the hls cDNA predicts a protein with amino-terminal homology to members of the DE-H family of RNA-dependent ATPases and putative helicases. Similarity of 51% in the amino-terminal third of the protein was found to two yeast splicing factors, PRP2 and PRP16, and to Drosophila Maleless, which is required for dosage compensation. To analyze Hls function, RNA localization patterns were determined for seven different transcripts in hls mutant ovaries. Previtellogenic transport to the oocyte was unaffected for all transcripts examined. Transport and localization of bicoid and oskm messages during vitellogenic stages were strongly disrupted, and the distribution and/or quantity of gurken, orb, and fs(3)KIO mRNAs were also affected, but to a lesser degree. In contrast, hu-li tai shao and Biicaudul-D transcripts were transported and localized normally in hls mutants. In addition, Kinesin heavy chain:p-Galactosidase fusion protein failed to localize correctly to the posterior of the oocyte in vitellogenic egg chambers. Examination of the microtubule structure with anti-a-Tubulin antibodies revealed aberrant microtubule organizing center movement and an abnormally dense cytoplasmic microtubule meshwork. We discuss potential roles for Hls in organizing a cytoskeletal framework essential for localizing specific RNAs.

Components of the RNAi Machinery That Mediate Long-Distance Chromosomal Associations Are Dispensable for Meiotic and Early Somatic Homolog Pairing inDrosophila melanogaster

“…Stocks with the following alleles were used: dcr-2 L811fsx and dcr-2 R416x , ago2 414 (Okamura et al 2004), ago2 51b (Xu et al 2004), aub HN2 and aub QC42 (Schü pbach and Wieschaus 1991), spn-E 1/E616 and spn-E hls-D125 (Gillespie and Berg 1995), piwi 1 (Cox et al 1998) and mnk(lok) p6 (Brodsky et al 2004). Embryos from piwi 1 homozygous clones were generated using the FLP-DFS system Perrimon 1992, 1996).…”

An Egalitarian-BicaudalD complex is essential for oocyte specification and axis determination in Drosophila.

“…Oocyte determination requires egl and BicD; oo cyte positioning requires the function of a number of genes such as dicephalic, homeless, and spindleC (Frey et al 1984;Gonzalez-Reyes and St Johnston 1994;Gillespie and Berg 1995). Oocyte determination both re quires and stabilizes a polarized microtubule network that leads to microtubule-mediated transport of RNA from the nurse cells into the future oocyte (Theurkauf et al 1993).…”

Drosophila mus301/spindle-C Encodes a Helicase With an Essential Role in Double-Strand DNA Break Repair and Meiotic Progression

“…The loss of function of the spindle genes in the germline produces defects consistent with their role in the selection of the oocyte, the posterior positioning of the oocyte within the egg chamber, and the polarization of the anterior-posterior and dorsal-ventral axes of the follicle (Gillespie and Berg 1995;González-Reyes et al 1997;Ghabrial et al 1998;Abdu et al 2003;Staeva-Vieira et al 2003). The cloning of okra, spn-A, spn-B, and spn-D established a clear link between these genes and dsDNA break repair.…”