Date of Award
Fall 2025
Document Type
Open Access Dissertation
Department
Biological Sciences
First Advisor
Alissa Armstrong
Abstract
Humans have complex signaling pathways that allow them to store and expend energy based on nutritional quality and availability. Inter-organ signaling is used to communicate nutrient availability between organs based on nutritional needs and the rate of cellular division. Our main overarching question is to investigate how fat-derived signals affect adipocyte morphology and the maintenance of stem cells in the ovary. While signaling pathways, like insulin and mTOR, and some adipokines that are involved in inter-organ nutrient sensing have been identified, the exact nutrient reliant mechanisms of stem cell maintenance are not completely understood. Using Drosophila melanogaster as a model, we investigated how different molecular aspects of nutrient sensing mediate adipose tissue control of oogenesis. Using transgenic Drosophila lines to target specific adipokines in the fat, we examined the how the knockdown of the amino acid transporter CD98hc (Chapter 3), the components of the Ras/MAPK signaling cascade (Chapter 4), and a subset of adipokines needed for development (Chapter 5) were utilized in maintaining adipocyte size, lipid droplet composition, and oogenesis at multiple stages. We hypothesized that the fat derived components of those pathways are needed to maintain normal ovary function and adipocyte homoeostasis. The knockdown of CD98hc in adipocytes resulted in increased amounts of blocked ovulation and increased triglyceride storage in adipocytes (Chapter 3). By knocking down the components of the Ras/MAPK pathway in the fat we observed smaller adipocyte size, lipid droplet size, and lower amounts of stored triglycerides in adipocytes (Chapter 4). We observed increased cell death in the ovary, increases in the amount of dying vitellogenic follicles in the ovariole, and instances of increased triglyceride storage in adipocytes when the adipokines egr, upd2, and CCHa1 were knocked down in the fat (Chapter 5). From this work, we identified signaling components that influence ovarian and adipocyte homeostasis and may have a more general role in relaying nutrient status to additional nutrient responsive organs.
Rights
© 2025, Chad Herbert Simmons
Recommended Citation
Simmons, C. H.(2025). Adipokines Mediate Fat-To-Ovary Communication to Regulate Oogenesis, Adipocyte Size, and Lipid Storage in Drosophila Melanogaster. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8644