Date of Award
5-31-2022
Document Type
Campus Access Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
Jens Rister
Second Advisor
Alexey Veraksa
Third Advisor
Kellee Siegfried-Harris
Abstract
The conserved Hippo tumor suppressor pathway balances cell proliferation and apoptosis. In Drosophila melanogaster, the Hippo pathway also plays a non-canonical role to post-mitotically regulate the specification of color-sensing photoreceptors. Green-sensitive (Rh6) or blue-sensitive (Rh5) pigments are expressed when the Hippo pathway is ON or OFF, respectively. I used the Drosophila eye as a model to identify novel regulators of the Hippo pathway. First, I investigated “daltonien”, a mutation that causes a dramatic loss of Rh5 photoreceptors and gain of Rh6 photoreceptors, and narrowed down a potentially affected gene. Moreover, I performed two high throughput screens to identify novel regulators of the pathway in vivo. First, I pursued an RNAi-based water immersion approach with a post-mitotic photoreceptor-specific driver (lGMR-Gal4) and a Rh5>GFP reporter as a readout for Rh5 (Hippo OFF) photoreceptors. We performed a differential gene expression analysis on transcriptomes of Rh6 (Hippo ON) and Rh5 (Hippo OFF) photoreceptors and screened for genes whose knockdown caused a deviation from the wildtype 35:65 Rh5:Rh6 photoreceptors ratio. I identified 17 genes as potential regulators of the pathway. Next, I pursued a CRISPR/Cas9-based approach to identify G-protein coupled receptors (GPCRs) that regulate the pathway in early or late eye development. I used gRNA lines for all known Drosophila GPCRs (from Dr. Schlichting, Brandeis) in combination with the eye-specific driver GMR-GAL4 to screen for GPCRs whose knockout caused adult eye defects. I also used the binary readout of Rh5 vs. Rh6 fate to identify GPCRs that regulate the Hippo pathway in terminal fate decisions. I identified 11 GPCRs required for eye development and one regulator of the Hippo pathway in the post-mitotic context. Taken together, I identified novel regulators of the Hippo pathway in eye growth and post-mitotic photoreceptor fate decisions. These findings could inspire the development of novel drugs and cancer therapies.
Recommended Citation
Bashir, Mhamed, "Identification of Novel Regulators of the Hippo Tumor Suppressor Pathway in the Drosophila Eyeidentification of Novel Regulators of the Hippo Tumor Suppressor Pathway in the Drosophila Eye" (2022). Graduate Masters Theses. 740.
https://scholarworks.umb.edu/masters_theses/740
Comments
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