BMP Signaling Pathway Regulates Phagocytosis And Hematopoietic Function In Drosophila

Innate immunity is the first line of defense for Drosophila against the invasion of bacteria,which is divided into humoral immunity and cellular immunity.Phagocytosis of plasmatocytes is an important component of cellular immunity and is responsible for removing invading pathogenic bacteria and apoptotic cells produced in development.The molecular mechanism of plasmatocytes phagocytosis remains unclear.The lymph gland is the main hematopoietic organs in the larval stage of drosophila,which is divided into three regions according to cell type,cortical area,medullary area and PSC.Under normal circumstances,the lymph gland should be in homeostasis,but the molecular mechanisms involved in this homeostasis are still unclear.The bone morphogenetic protein(BMP)is a member of the transformational growth factor β(TGF-β)superfamily and is involved in a variety of biological processes,including oogenesis,embryonic mesoderm formation,midgut morphogenesis and stem cell maintenance.The function of BMP signaling pathways in phagocytosis and lymph gland homeostasis maintenance is unclear.In this study,the UAS-Gal4 system and the BMP signaling pathway RNAi drosophila were used to analyse BMP-signaling genes involved in plasmatocytes phagocytosis and lymph gland homeostasis.In addition,the effect of gbb genes on hematopoietic homeostasis was focused,and the role of gbb genes in hemocyte proliferation and differentiation was analyzed by using genetic and cell biology techniques.The main findings of this paper are as follows:1.In larval,Dpp,Gbb,Tkv,Wit,Brk and Omb promote plasmatocytes phagocytosis of Fluo Sphere Microspheres,Dpp,Gbb,Tkv,Wit and Brk promote plasmatocytes phagocytosis of gram-negative bacteria,and Gbb promotes plasmatocytes phagocytosis of gram-positive bacteria.In adult,Gbb promotes plasmatocytes phagocytosis of Fluo Sphere Microspheres,while Put inhibits it.2.In the CZ region,Gbb,Wit,Put,Sal and Brk inhibit plasmatocytes differentiation,in the MZ region,Dpp and Put promote the differentiation of progenitors,Gbb,Wit,Sax,Med,Mad,Sal and Brk inhibit the differentiation of progenitors.3.The gbb gene is widely expressed in lymph glands.Gbb inhibits EGFR and JNK signaling pathways,thereby inhibiting the differentiation of lamellocytes and the proliferation of lymph gland cells.In the CZ region,Gbb inhibits plasmatocytes differentiation by inhibiting the EGFR signaling pathway.Gbb inhibits the differentiation of crystal cells in progenitors and intermediate progenitors.In summary,BMP signaling pathway genes play an important role in plasmatocytes phagocytosis and hematopoietic function.Gbb plays an important role in regulating the differentiation of lamellocytes,plasmatocytes and crystal cells.This study further deepens the connection between BMP signaling pathway and hematopoietic function,and provides a theoretical basis for studying the molecular mechanism of blood diseases.