The ABC Transporter Promotes Cell Clearance in the Ovary.

The clearance of dead cells is a fundamental process in the maintenance of tissue homeostasis. Genetic studies in , , and mammals have identified two evolutionarily conserved signaling pathways that act redundantly to regulate this engulfment process: the and pathways. Of these engulfment genes, only the ortholog remains to be identified in Homology searches have revealed a family of putative homologs encoding ATP-binding cassette (ABC) transporters in To determine which of these genes functions similarly to , we analyzed mutants for engulfment phenotypes in oogenesis, during which nurse cells (NCs) in each egg chamber undergo programmed cell death (PCD) and are removed by neighboring phagocytic follicle cells (FCs).

Control of non-apoptotic nurse cell death by engulfment genes in Drosophila.

Programmed cell death occurs as a normal part of oocyte development in Drosophila. For each egg that is formed, 15 germline-derived nurse cells transfer their cytoplasmic contents into the oocyte and die. Disruption of apoptosis or autophagy only partially inhibits the death of the nurse cells, indicating that other mechanisms significantly contribute to nurse cell death.

Analysis of Phagocytosis in the Drosophila Ovary.

Programmed cell death (PCD) is essential for health and development. Generally, the last step of PCD is clearance, or engulfment, by phagocytes. Engulfment can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification of the engulfed material.

Components of the Engulfment Machinery Have Distinct Roles in Corpse Processing.

Billions of cells die in our bodies on a daily basis and are engulfed by phagocytes. Engulfment, or phagocytosis, can be broken down into five basic steps: attraction of the phagocyte, recognition of the dying cell, internalization, phagosome maturation, and acidification. In this study, we focus on the last two steps, which can collectively be considered corpse processing, in which the engulfed material is degraded.

Polarization of the epithelial layer and apical localization of integrins are required for engulfment of apoptotic cells in the Drosophila ovary.

Inefficient clearance of dead cells or debris by epithelial cells can lead to or exacerbate debilitating conditions such as retinitis pigmentosa, macular degeneration, chronic obstructive pulmonary disease and asthma. Despite the importance of engulfment by epithelial cells, little is known about the molecular changes that are required within these cells. The misregulation of integrins has previously been associated with disease states, suggesting that a better understanding of the regulation of receptor trafficking could be key to treating diseases caused by defects in phagocytosis.

Detection of Cell Death and Phagocytosis in the Drosophila Ovary.

Billions of cells die and are cleared throughout the development and homeostasis of an organism. Either improper death or clearance can lead to serious illnesses. In the adult Drosophila ovary, germline cells can die by programmed cell death (PCD) at three distinct stages; here we focus on cell death that occurs in mid- and late oogenesis.

Use of necrotic markers in the Drosophila ovary.

Necrosis is a form of cell death characterized by cytoplasmic and organelle swelling, compromised -membrane integrity, intracellular acidification, and increased levels of reactive oxygen species (ROS) and cytosolic Ca(2+). In the Drosophila ovary, two distinct forms of cell death occur naturally. In response to starvation, caspase-dependent cell death occurs during mid-oogenesis.

Draper acts through the JNK pathway to control synchronous engulfment of dying germline cells by follicular epithelial cells.

The efficient removal of dead cells is an important process in animal development and homeostasis. Cell corpses are often engulfed by professional phagocytes such as macrophages. However, in some tissues with limited accessibility to circulating cells, engulfment is carried out by neighboring non-professional phagocytes such as epithelial cells.