Requirement for Croquemort in Phagocytosis of Apoptotic Cells in Drosophila

Abstract

Macrophages in the Drosophila embryo are responsible for the phagocytosis of apoptotic cells and are competent to engulf bacteria. Croquemort (CRQ) is a CD36-related receptor expressed exclusively on these macrophages. Genetic evidence showed that crq was essential for efficient phagocytosis of apoptotic corpses but was not required for the engulfment of bacteria. The expression of CRQ was regulated by the amount of apoptosis. These data define distinct pathways for the phagocytosis of corpses and bacteria in Drosophila.

Structural and functional characterization of pseudopodocyte, a shaggy immune cell produced by two Drosophila species of the obscura group

“…Pseudopodocytes thus, seem to behave like plasmatocytes rather than lamellocytes. Plasmatocytes are also known to be involved in the phagocytosis of apoptotic cells and hydrolyzed tissue during Drosophila development (Franc et al, 1999;Lanot et al, 2001). So, phagocytic activities of plasmatocytes are essential for Drosophila development but happen to be involved in immunity defenses, too.…”

“…Their cytoplasm encloses a well-developed Golgi apparatus, a rough endoplasmic reticulum (RER) developed in large cisternae, numerous free ribosomes, lipidic vesicles, and phagolysosome-like inclusions (Ribeiro and Brehélin, 2006). Plasmatocytes are involved in phagocytosis, wound healing, production of antimicrobial peptides and, probably, in foreign body recognition, too (Brehélin, 1982;Franc et al, 1999;Ribeiro and Brehélin, 2006;Samakovlis et al, 1990;Dimarcq, 1997;Tzou et al, 2002;Meister, 2004;Charoux and Royet, 2009). They also contribute to encapsulation: they were shown attaching to the chorion of a parasitoid egg within a few hours after parasitization, thus being the first cells to come in contact with the foreign body at the very beginning of capsule formation (Russo et al, 1996;Williams et al, 2005).…”

CD36: Implications in cardiovascular disease

“…CD36 is classified as a class B scavenger receptor (Platt, & Gordon, 1998,Krieger, 1997, and is part of a gene family that includes lysosomal integral membrane protein II (LIMP-II), which plays a role in nerve myelinization (Gamp, et al, 2003), CD36 and LIMP-II analogous-I protein (CLA-1) (known as scavenger receptor BI (SR-BI) in mice), which mediates the selective uptake of cholesterol esters from high density lipoprotein (HDL) (Acton, Rigotti, Landschulz, Xu, Hobbs, & Krieger, 1996), and Croquemorte, a drosophila protein, that phagocytoses apoptotic cells and senescent erythrocytes (Franc, Dimarcq, Lagueux, Hoffmann, & Ezekowitz, 1996,Franc, Heitzler, Ezekowitz, & White, 1999. Scavenger receptors are found in both primitive and immunologically advanced organisms and their continued evolutionary conservation suggest their important role at the forefront of the initial organism response to pathogens and in normal homeostasis (Krieger, 1997,Gordon, 2002.…”

How Drosophila combats microbial infection: a model to study innate immunity and host–pathogen interactions

“…One of the functions of embryonic blood is to ingest apoptotic cells by phagocytosis. In addition, it has also been shown that blood cells have the capacity to engulf microbes injected into the embryo [8]. Toward the end of embryogenesis, the lymph glands (the larval haematopoietic organ) differentiate along the anterior portion of the dorsal vessel (Figure 3a).…”