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Novel insights into the non-neuronal expression & function of the RNA-binding protein Alan Shepard (Shep) during D. melanogaster Oogenesis

Almoalem, Abdulla 2023. Novel insights into the non-neuronal expression & function of the RNA-binding protein Alan Shepard (Shep) during D. melanogaster Oogenesis. PhD Thesis, Cardiff University.
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In Drosophila, the major body axes of the adult fly are established during oogenesis. This is achieved within the oocyte cytoplasm through the asymmetric distribution and local translation of key maternal mRNAs, such as oskar and gurken. The spatiotemporal regulation of these mRNAs is tightly controlled at the post-transcriptional level by the dynamic remodelling of their ribonucleoprotein complexes. The D. melanogaster alan shepard (shep) gene encodes a highly conserved RNA-binding protein with two RNA-recognition motifs. Although shep has been predominantly studied in the nervous system, much remains unknown about its molecular function in other tissues. In a yeast two-hybrid screen, our group identified Shep as a potential interacting partner of the RNA-binding protein PTB, a known regulator of oskar and gurken mRNAs. Therefore, we decided to characterize the expression patterns and potential roles of the Drosophila Shep during oogenesis. Our in vivo characterization revealed that Shep localizes to the oocyte cortex during mid-oogenesis with enrichment at the posterior and dorsal-anterior corners, where oskar and gurken mRNAs are restricted to define posterior and dorsal fate, respectively. Furthermore, we demonstrated that Shep interacts with oskar and gurken mRNAs in vivo and in vitro. Moreover, overexpression of Shep reduced Oskar and Gurken levels, which compromised body axis formation. Conversely, shep loss-of-function led to the ectopic and premature translation of oskar mRNA within the oocyte cytoplasm. Our work reveals a novel non-neuronal role for shep in Drosophila body axis patterning by regulating oskar and gurken mRNAs. Here, we show that shep is transcribed into various ovarian mRNA transcripts leading to the expression of several isoforms with distinct localization patterns. We also demonstrate that the conserved Delta-Notch signalling pathway regulates shep expression within ovarian somatic cells. Moreover, we provide in vivo and in vitro evidence suggesting that Shep and PTB are part of similar RNP complexes in the ovary and may work together to regulate a variety of mRNAs at the post-transcriptional level

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: Biosciences
Subjects: Q Science > Q Science (General)
Date of First Compliant Deposit: 2 January 2024
Last Modified: 03 Jan 2024 14:32

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