Translational control of autophagy by Orb in the Drosophila germline [mature]
Ontology highlight
ABSTRACT: Drosophila Orb, the homologue of vertebrate CPEB is a key translational regulator involved in oocyte polarity and maturation through poly(A) tail elongation of specific mRNAs. orb has also an essential function during early oogenesis which has not been addressed at the molecular level. Here, we show that orb prevents cell death during early oogenesis, thus allowing oogenesis to progress. It does so through the repression of autophagy, by directly repressing, together with the CCR4 deadenylase, the translation of Autophagy-specific gene 12 (Atg12) mRNA. Autophagy and cell death observed in orb mutant ovaries are reduced by decreasing Atg12 or other Atg mRNA levels. These results reveal a role of Orb in translational repression and identify autophagy as an essential pathway regulated by Orb during early oogenesis. Importantly, they also establish translational regulation as a major mode of control of autophagy, a key process in cell homeostasis in response to environmental cues.
Project description:Drosophila Orb, the homologue of vertebrate CPEB is a key translational regulator involved in oocyte polarity and maturation through poly(A) tail elongation of specific mRNAs. orb has also an essential function during early oogenesis which has not been addressed at the molecular level. Here, we show that orb prevents cell death during early oogenesis, thus allowing oogenesis to progress. It does so through the repression of autophagy, by directly repressing, together with the CCR4 deadenylase, the translation of Autophagy-specific gene 12 (Atg12) mRNA. Autophagy and cell death observed in orb mutant ovaries are reduced by decreasing Atg12 or other Atg mRNA levels. These results reveal a role of Orb in translational repression and identify autophagy as an essential pathway regulated by Orb during early oogenesis. Importantly, they also establish translational regulation as a major mode of control of autophagy, a key process in cell homeostasis in response to environmental cues. Orb RIP-chip vs mock IP on ovaries from mature 3-5 day old females.
Project description:Drosophila Orb, the homologue of vertebrate CPEB is a key translational regulator involved in oocyte polarity and maturation through poly(A) tail elongation of specific mRNAs. orb has also an essential function during early oogenesis which has not been addressed at the molecular level. Here, we show that orb prevents cell death during early oogenesis, thus allowing oogenesis to progress. It does so through the repression of autophagy, by directly repressing, together with the CCR4 deadenylase, the translation of Autophagy-specific gene 12 (Atg12) mRNA. Autophagy and cell death observed in orb mutant ovaries are reduced by decreasing Atg12 or other Atg mRNA levels. These results reveal a role of Orb in translational repression and identify autophagy as an essential pathway regulated by Orb during early oogenesis. Importantly, they also establish translational regulation as a major mode of control of autophagy, a key process in cell homeostasis in response to environmental cues. Orb RIP-chip vs mock IP on ovaries from newly eclosed females.
Project description:Drosophila Orb, the homologue of vertebrate CPEB is a key translational regulator involved in oocyte polarity and maturation through poly(A) tail elongation of specific mRNAs. orb has also an essential function during early oogenesis which has not been addressed at the molecular level. Here, we show that orb prevents cell death during early oogenesis, thus allowing oogenesis to progress. It does so through the repression of autophagy, by directly repressing, together with the CCR4 deadenylase, the translation of Autophagy-specific gene 12 (Atg12) mRNA. Autophagy and cell death observed in orb mutant ovaries are reduced by decreasing Atg12 or other Atg mRNA levels. These results reveal a role of Orb in translational repression and identify autophagy as an essential pathway regulated by Orb during early oogenesis. Importantly, they also establish translational regulation as a major mode of control of autophagy, a key process in cell homeostasis in response to environmental cues.
Project description:We used microarrays to identify mRNAs regulated by Orb, the Drosophila CPEB homolog, during oogenesis. We analyzed RNA recovered from immunoprecipitation experiments and transcriptomes of wild-type and orb mutant females. Keywords: mRNA targets of a regulatory protein
Project description:Localized protein translation is critical in many biological contexts, particularly in highly polarized cells, such as neurons, to regulate gene expression in a spatiotemporal manner. The cytoplasmic polyadenylation element-binding (CPEB) family of RNA-binding proteins has emerged as a key regulator of mRNA transport and local translation required for early embryonic development, synaptic plasticity, and long-term memory (LTM). Drosophila Orb and Orb2 are single members of the CPEB1 and CPEB2 subfamilies of the CPEB proteins, respectively. At present, the identity of the mRNA targets they regulate is not fully known, and the binding specificity of the CPEB2 subfamily is a matter of debate. Using transcriptome-wide UV cross-linking and immunoprecipitation, we define the mRNA-binding sites and targets of Drosophila CPEBs. Both Orb and Orb2 bind linear cytoplasmic polyadenylation element-like sequences in the 3′ UTRs of largely overlapping target mRNAs, with Orb2 potentially having a broader specificity. Both proteins use their RNA-recognition motifs but not the Zinc-finger region for RNA binding. A subset of Orb2 targets is translationally regulated in cultured S2 cells and fly head extracts. Moreover, pan-neuronal RNAi knockdown of these targets suggests that a number of these targets are involved in LTM. Our results provide a comprehensive list of mRNA targets of the two CPEB proteins in Drosophila, thus providing insights into local protein synthesis involved in various biological processes, including LTM.
Project description:In this study we show that Drosophila Tudor-domain containing protein 5-like (Tdrd5l) is important for post-transcriptional regulation of maternal mRNAs. Tdrd5l localizes to a novel of body in the germline and interacts with post-transcriptional regulation pathways. In mutant females we observe accumulation of Gurken and its activator Orb in nurse cells during oogenesis. Decreased orb function suppresses the Tdrd5l-mutant phenotype, indicating that this is a primary defect in these mutants.
Project description:Autophagy is critical for protecting HSCs from metabolic stress. Here, we used a genetic approach to inactivate autophagy in adult HSCs by deleting the Atg12 gene. We show that loss of autophagy causes accumulation of mitochondria and an oxidative phosphorylation (OXPHOS)-activated metabolic state, which drives accelerated myeloid differentiation likely through epigenetic deregulations rather than transcriptional changes, and impairs HSC self-renewal activity and regenerative potential. To determine how loss of autophagy affects gene expression, we conducted microarray analysis of purified control and Atg12 conditional knockout HSCs.