Adult stem cells are key components of animal biology, with the vital task of replenishing cells in numerous tissue types. This function hinges on the prior specification and arrangement of requisite numbers of stem cells and supportive niche cells during development.
Here, I investigate the signaling pathways which act on adult Drosophila ovarian Follicle Stem Cells (FSCs) and their niche cells, Escort Cells (ECs) and Follicle Cells (FCs), during pupal development; location of a cell upon eclosion determines cell identity. Using lineage tracing approaches, we examine how the Wnt, JAK-STAT, Hippo, and Hedgehog pathways influence precursor behaviors, namely cell division, location, and survival, with a focus on the novel process underlying budding of the first egg chamber midway through pupation.
We find that pupal Intermingled Cells (ICs), the precursors to adult ECs, FSCs, and FCs, are also the source of Extra Germarial Crown (EGC) cells and basal stalk cells which surround the first budded egg chamber. As in adults, Wnt primarily affects precursor location, with high Wnt corresponding to anterior cell fates and low Wnt producing a posterior bias. JAK-STAT has a similar, but reverse, effect on location, and appears to contribute to division in posterior locations.
The Hippo pathway, mediated by its effector Yorkie (Yki), mainly affects precursor division and survival, with some effects on location. The role of the Hedgehog pathway in precursor division and posterior movement appears to be mediated via Yki activity. Understanding these developmental processes could contribute to generating organoids for therapeutic discovery.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/1a8p-z897 |
| Date | January 2024 |
| Creators | Misner, Rachel Lotty |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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