Cell death and clearance are vital processes throughout development and in maintaining homeostasis. Apoptosis, autophagic cell death, and necroptosis are the most well characterized forms of programmed cell death; however, alternative cell death pathways are being discovered and characterized. During oogenesis in Drosophila, fifteen nurse cells support the oocyte through development. During late stages of oogenesis these fifteen nurse cell die and are cleared in a developmentally regulated form of cell death. This application aims to identify the mechanism of developmentally regulated cell death and clearance of nurse cells in late oogenesis. Preliminary data suggest a non-autonomous cell death induced by the surrounding stretch follicle cells.
The first aim consists of characterizing the role of lysosomes in nurse cell death and clearance. Ex vivo live imaging and an RNAi screen of lysosomal processing genes will be utilized.
The second aim i s to determine how the stretch follicle cells surround the nurse cells. More specifically, I will use a genetic construct, Flybow, that expresses different fluorophores in a homogenous cell population; this will allow for tracking of individual stretch follicle cells through confocal microscopy. I will alo inhibit stretch follicle cell extension by pharmacological agents and dominant negative GTPases to test the requirements of stretch follicle cells surrounding nurse cells for their death and clearance.
The third aim i s to identify signaling molecules necessary for death and clearance of the nurse cells. This will be accomplished by identifying the secretome, the sum of all secreted molecules, of the stretch follicle cells by mass spectrometry. An RNAi screen of the secretome will be conducted in parallel. Altogether the goal of this application is to understand the mechanistic process of nurse cell death and clearance. The information gained from this work will be beneficial to better understanding non-apoptotic cell death in humans.

Public Health Relevance

Cell death and clearance of dead cells are important aspects of development and homeostasis of an organism. There are multiple forms of cell death, but only apoptosis is well understood. This application aims to better characterize a poorly understood form of non-apoptotic cell death and clearance of corpses.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZRG1)
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Brown, Patrick
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Boston University
Schools of Arts and Sciences
United States
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Timmons, Allison K; Mondragon, Albert A; Meehan, Tracy L et al. (2017) Control of non-apoptotic nurse cell death by engulfment genes in Drosophila. Fly (Austin) 11:104-111