Scrambled Eggs: Apoptotic Cell Clearance by Non-Professional Phagocytes in the Drosophila Ovary

Abstract

For half of a century, it has been known that non-professional phagocytes, such as fibroblasts, endothelial, and epithelial cells, are capable of efferocytosis (engulfment of apoptotic cells). Non-professional phagocytes differ from professional phagocytes in the range and efficiency of engulfment. Much of the recognition and underlying signaling machinery between non-professional and professional phagocytes is the same, but it is not known how the engulfment capacity of non-professional phagocytes is controlled. Moreover, the signaling networks involved in cell corpse recognition, engulfment, and phagosome maturation are only partially understood. The Drosophila ovary provides an excellent system to investigate the regulation of phagocytic activity by epithelial cells, a major class of non-professional phagocytes. During Drosophila oogenesis, mid-stage egg chambers undergo apoptosis of the germline in response to nutrient deprivation. Epithelial follicle cells then undergo major cell shape changes and concomitantly engulf the germline material. Our previous work has established that Draper and the integrin α-PS3/β-PS heterodimer are required in follicle cells for germline cell clearance. In addition, we have characterized phagosome maturation pathways, and found that the JNK pathway amplifies the engulfment response. In this review, we discuss recent advances on the interplay between engulfment pathways in the follicular epithelium for cell clearance in the Drosophila ovary. We also provide a comparison to apoptotic cell clearance mechanisms in C. elegans and mammals, illustrating strong conservation of efferocytosis mechanisms by non-professional phagocytes.

Chemokine Receptors and Phagocyte Biology in Zebrafish

“…Phagocytes are broadly divided into professional and non-professional phagocytes (1). In non-professional phagocytes like epithelial cells, endothelial cells, and fibroblasts, phagocytosis is a facultative function as these cells have other tissue-resident functions, although they can contribute to tissue homeostasis by phagocytosing apoptotic debris (2). In contrast, professional phagocytes efficiently identify, engulf, and clear invading pathogens, harmful substances, and dying cells.…”

“…Opsonic receptors recognize targets detected and bound by soluble host molecules, such as complement proteins and antibodies. Receptors for apoptotic cells recognize soluble cues secreted by dying cells (e.g., lysophosphatidylcholine and ATP) or characteristic molecules exposed on the surface of dying cells, such as phosphatidylserine (1,2). Professional phagocytes play pivotal roles in immunomodulation, development, pathogen clearance and antigen presentation (2,3).…”

Extracellular Vesicle Transfer from Endothelial Cells Drives VE-Cadherin Expression in Breast Cancer Cells, Thereby Causing Heterotypic Cell Contacts

“…mCherry-tagged lifeact proved cytoskeleton remodeling in MCF7 cells ( Figure 7 D). Lamellipodia formation and cytoskeleton reorganization would support the hypothesis that phagocytic clearance of dying cells (efferocytosis) is a mechanism by which MCF7 cells take up extracellular vesicles from dying HUVECs ( Figure 7 A,D) [ 34 , 35 ]. Therefore, the area of colocalized mCherry and GFP fluorescence increased over time ( Figure 7 B,E) due to the increasing number of HUVEC-derived, GFP-containing vesicles inside TCs ( Figure 7 C).…”

Upregulated IGF‑1 in the lungs of asthmatic mice originates from alveolar macrophages

“…IGF-1 promotes the phagocytosis of AECs. IGF-1 signaling is involved in the inflammatory response (18); the role of non-professional phagocytosis in the inflammatory response has been reported (19). Thus, whether IGF-1 affects the phagocytosis of AECs, non-professional phagocytes, was investigated in the present study.…”