The Role of SR Splicing Protein 9G8 in Regulating Lipid Metabolism in Drosophila Intestine
Open Access
- Author:
- Voskoboynikov, Roman
- Area of Honors:
- Biochemistry and Molecular Biology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Justin Di Angelo, Thesis Supervisor
Jeanne Marie Rose, Thesis Honors Advisor - Keywords:
- Drosophila
9G8
SR protein
Intestine
Metabolism
Splicing - Abstract:
- For the last several decades, the rate of metabolic diseases in humans, such as obesity or diabetes (type 2), has been increasing drastically. These diseases arise from defects in the body’s ability to take in and store nutrients such as carbohydrates and triglycerides. To better understand the pathways which our body uses to absorb and store nutrients, a simpler, yet similar organism, such as Drosophila melanogaster, can be used as a model system. Previous studies have shown splicing factors – proteins that assist alternative splicing of mRNA – to have an impact on lipid storage in the fly body. Specifically, adipose tissue knockdown of SR proteins, which are a group of splicing factors that regulate splice-site selection, revealed an increase in triglyceride storage in whole flies. However, whether SR proteins function in other tissues to regulate nutrient metabolism was not known. We focused on studying the role of SR proteins in fly intestines by decreasing their levels in the gut and measuring the relative concentrations of lipids and carbohydrates. In total, we explored eight such proteins, including 9G8, B52, SF2, SC35, Rbp1, Rbp1-Like, RSF1, and SRp54. Among those, RSF1 limits overall triglyceride levels, while Rbp1 promotes the storage of triglycerides in both male and female flies. Other SR proteins, including 9G8, SC35, Rbp1-Like, SF2, and Srp54 also seem to alter whole fly triglyceride stores, in only one of the sexes. RSF1 was also found to reduce overall glycogen storage, while Rbp1 functioned to promote it in both sexes. Additionally, SC35, SF2, and Srp54 were found to diminish overall available free glucose, while B52 enhanced its production in female flies. We next further investigated 9G8, an SR protein which displayed a prominent lipid phenotype in both the fat body and intestine. After using RNA-seq to identify differentially expressed genes, we utilized qPCR to confirm the differential expression of lipid processing enzymes, such as lipases and fatty acid synthases and fatty acid elongases. Overall, we determined most SR proteins to have a unique phenotype in the fly intestine and found 9G8 to regulate whole body, as well as intestinal, lipid homeostasis by altering the expression of genes involved in metabolism of lipids.