Drosophila Orb, the homolog of vertebrate CPEB, is a key translational regulator involved in oocyte polarity and maturation through poly(A) tail elongation of specific mRNAs. orb also has an essential function during early oogenesis that 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.
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http://dx.doi.org/10.1016/j.devcel.2015.11.003 | DOI Listing |
Curr Biol
January 2025
Department of Developmental Biology and Cancer Research, The Hebrew University of Jerusalem Faculty of Medicine, Ein-Kerem Campus, Jerusalem 9112102, Israel; Institute for Medical Research, Israel-Canada (IMRIC), Ein-Kerem Campus, Jerusalem 9112102, Israel. Electronic address:
Vertebrate oocyte polarity has been observed for two centuries and is essential for embryonic axis formation and germline specification, yet its underlying mechanisms remain unknown. In oocyte polarization, critical RNA-protein (RNP) granules delivered to the oocyte's vegetal pole are stored by the Balbiani body (Bb), a membraneless organelle conserved across species from insects to humans. However, the mechanisms of Bb formation are still unclear.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Entomology, University of California, Riverside, CA 92521.
Female mosquitoes require a vertebrate blood meal to activate reproduction, transmitting numerous devastating human diseases. Vitellogenesis is a central event of female reproduction that involves the massive production of vitellogenin (Vg) in the fat body and the maturation of ovaries. This process is controlled by the steroid hormone 20-hydroxyecdysone (20E); however, its molecular regulatory basis remains not completely understood.
View Article and Find Full Text PDFBiology (Basel)
December 2024
Amphibian Biology Group, Department of Evolutionary Biology and Conservation of Vertebrates, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland.
The gonads of amphibians, like other vertebrates, consist of somatic tissues, which create a specific environment essential for the differentiation of germline cells. The earliest stages of gametogenesis still remain underexplored in anuran amphibians. We propose to introduce the term "pregametogenesis" for a specific period of gonocyte proliferation and differentiation that occurs exclusively during the early stages of gonadal development.
View Article and Find Full Text PDFGenome Biol
January 2025
College of Life Sciences, Key Laboratory of Animal Reproduction and Biotechnology in Universities of Shandong, Qingdao Agricultural University, Qingdao, 266109, China.
Background: In humans and other mammals, the process of oogenesis initiates asynchronously in specific ovarian regions, leading to the localization of dormant and growing follicles in the cortex and medulla, respectively; however, the current understanding of this process remains insufficient.
Results: Here, we integrate single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) to comprehend spatial-temporal gene expression profiles and explore the spatial organization of ovarian microenvironments during early oogenesis in pigs. Projection of the germ cell clusters at different stages of oogenesis into the spatial atlas unveils a "cortical to medullary (C-M)" distribution of germ cells in the developing porcine ovaries.
Front Cell Dev Biol
December 2024
Department of Pediatric Surgery and Laboratory of Pediatric Surgery, West China Hospital/West China School of Medicine, Sichuan University, Chengdu, China.
Histone modification signatures mark sites of transcriptional regulatory elements and regions of gene activation and repression. These sites vary among cell types and undergo dynamic changes during development and in diseases. Oocytes produce numerous maternal factors essential for early embryonic development, which are significantly influenced by epigenetic modifications.
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