Almasoud, Jameela;
(2025)
Drosophila adipose tissue displays an apicobasal cell polarity and undergoes an epithelial-to-amoeboid transition driving cell dispersal by swimming migration.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The Drosophila adipose tissue, called the fat body, plays diverse roles in development including in energy storage, growth regulation, immune responses and wound healing. During embryonic and larval stages, the fat body exists as a flat, single-layered sheet that is surrounded by a basement membrane. As development progresses into the pupal stage, the fat body undergoes fat body remodeling, where fat body cells dissociate from neighboring cells and detach from the basement membrane to initiate amoeboid swimming cell migration. We hypothesize that fat body remodeling is similar to an epithelial-to-mesenchymal/amoeboid transition (EMT/EAT), a process essential for development and cancer metastasis. However, unlike epithelia, the fat body was not previously recognized to exhibit apicobasal polarity, a requisite for EMT. Surprisingly, my findings revealed that larval fat body cells display apicobasal polarity prior to fat body remodeling, despite being ensheathed by basement membrane. This polarity is shown to be essential for maintaining tissue integrity and supporting Collagen IV mediated cell-cell adhesion. This polarity is lost as remodeling begins. I show that GATA transcription factor, Serpent and Ecdysone signaling are critical regulators of polarity loss, as well as, dissociation of fat body cells and the initiation of swimming migration. Overall, my study reveals apicobasal polarity as a defining feature of the larval fat body cell, contributing to tissue integrity mediated via an unusual type of Collagen IV-mediated cell-cell adhesion. During metamorphosis, fat body remodeling represents an EMT/EAT-like transition, driven by Ecdysone signaling and Serpent, transforming the fat body tissue from a continuous sheet to individual migrating fat body cells that disperse throughout the pupal body.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Drosophila adipose tissue displays an apicobasal cell polarity and undergoes an epithelial-to-amoeboid transition driving cell dispersal by swimming migration |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Cell and Developmental Biology UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10211247 |
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