Biology subjects

Gavis, E. R.

Publications and source records attributed to Gavis, E. R..

3 recordsLinked to original sources

bioRxiv2023

Smaug regulates germ plasm synthesis and primordial germ cell number in Drosophila embryos by repressing the oskar and bruno 1 mRNAs

During Drosophila oogenesis, the Oskar (OSK) RNA-binding protein (RBP) determines the amount of germ plasm that assembles at the posterior pole of the oocyte. Here we identify the mechanisms that regulate the osk mRNA in the early embryo. We show that the Smaug (SMG) RBP is transported into the germ plasm of the early embryo where it accumulates in the germ granules. SMG binds to and represses translation of the osk mRNA itself as well as the bruno 1 (bru1) mRNA, which encodes an RBP that we show promotes germ plasm production. Loss of SMG or mutation of SMGs binding sites in the osk or bru1 mRNAs results in ectopic translation of these transcripts in the germ plasm and excess PGCs. SMG therefore triggers a post-transcriptional regulatory pathway that attenuates germ plasm synthesis in embryos, thus modulating the number of PGCs.

developmental biology↗

bioRxiv2022

Pseudouridine-dependent ribosome biogenesis regulates translation of polyglutamine proteins during Drosophila oogenesis

Stem cells in many systems, including Drosophila germline stem cells (GSCs), increase ribosome biogenesis and translation during terminal differentiation. Here, we show that pseudouridylation of ribosomal RNA (rRNA) mediated by the H/ACA box is required for ribosome biogenesis and oocyte specification. Reducing ribosome levels during differentiation decreased the translation of a subset of mRNAs that are enriched for CAG repeats and encode polyglutamine-containing proteins, including differentiation factors such as RNA-binding Fox protein 1. Moreover, ribosomes were enriched at CAG repeats within transcripts during oogenesis. Increasing TOR activity to elevate ribosome levels in H/ACA box-depleted germlines suppressed the GSC differentiation defects, whereas germlines treated with the TOR inhibitor rapamycin had reduced levels of polyglutamine-containing proteins. Thus, ribosome biogenesis and ribosome levels can control stem cell differentiation via selective translation of CAG repeat-containing transcripts.

developmental biology↗

bioRxiv2022

Overlapping and distinct cis-acting requirements for oskar mRNA localization pathways

Localization of oskar mRNA to the posterior of the Drosophila oocyte is essential for abdominal patterning and germline development. oskar localization is a multi-step process involving temporally and mechanistically distinct transport modes. Numerous cis-acting elements and trans-acting factors have been identified that mediate earlier motor-dependent transport steps leading to accumulation of oskar at the posterior. Little is known, however, about what features of oskar are required for the later localization phase, that occurs by diffusion with local entrapment and results in the accumulation of large oskar ribonucleoprotein granules by the end of oogenesis. Here we test whether cis- and trans-acting requirements for kinesin-dependent oskar transport, the structured oskar spliced localization element (SOLE) and the exon junction complex (EJC), are also required for late-phase localization. In contrast to kinesin-dependent motility, late-phase localization is independent of the EJC and depends not only on the structure but also the sequence of the SOLE. Late-phase localization also requires the oskar 3 UTR and we show that the 3 UTR is sufficient for ribonucleoprotein granule selectivity.

developmental biology↗