View Program - 63rd Annual Drosophila Research Conference

Obesity and malnutrition can influence nutrient signaling pathways that relay nutrient status throughout the body, yet the molecular components that allow communication about dietary input between different tissues is not completely understood. Drosophila melanogaster ovarian function is sensitive to changes in diet and serves as an ideal model to decipher how nutrient sensing by peripheral tissues influence the ovary. Previous studies demonstrate that Drosophila adipose tissue uses nutrient sensing pathways, like insulin/insulin-like growth factor and Target of Rapamycin signaling to modulate ovarian germline stem cells and their progeny (Armstrong et al., 2014; Armstrong and Drummond-Barbosa, 2018). Multiple adipokines, factors secreted from the adipose tissue, are required for tissue growth during larval development. The range of adipocyte-derived factors that contribute to adipocyte-to-ovary communication is not well understood. We propose that the adipokines with roles in larval growth, eiger (egr), unpaired2 (upd2), stunted (sun), growth blocking peptides (Gbp1, Gbp2, Gbp3) and CCH-amides (ccha2) also function to promote adipose tissue nutrient sensing control of oogenesis. We find that all are expressed in the adult female fat body. Using RT-PCR, we are determining if their expression is modulated by protein-poor and obesogenic diets. To determine their functional role, we use the Gal4/UAS gene expression system for RNAi-mediated knockdown of each adipokine specifically in adult adipocytes and measure effects on oogenesis using whole mount immunofluorescence and confocal microscopy. Thus far, we have observed that adipocyte knockdown of upd2 and egr leads to increased adipocyte size but does not affect germline stem cell number in the ovary. We are currently investigating the effects of adipokine knockdown on other aspects of oogenesis, including germline stem cell maintenance, germline cyst survival, progression through vitellogenesis and ovulation. Understanding how these adipokines communicate to the ovary will allow us to begin uncovering the cellular and molecular mechanisms that underlie signaling between adipose tissue and the germline stem cells.

Examining the Role of Adipokines in Regulating Oogenesis