Hortsch M, Olson A, Fishman S, Soneral S N, Marikar Y, Dong R, Jacobs J R
Department of Anatomy and Cell Biology, University of Michigan, Ann Arbor 48109-0616, USA.
Int J Dev Biol. 1998 Jan;42(1):33-42.
Using a novel monoclonal antibody we have studied the expression of a large proteoglycan-type molecule in Drosophila embryos. This molecule is secreted exclusively by migratory, embryonic hemocytes/macrophages and was therefore named MDP-1 for Macrophage-Derived Proteoglycan-1. Expression of MDP-1 begins late during hemocyte differentiation, after these cells have left their birthplace in the head mesoderm. At this time, macrophages are engaged in extracellular matrix deposition and the phagocytosis of cell debris generated by apoptotic events in various parts of the embryo, in particular from the developing central nervous system. Embryos deficient for programmed cell death display a greatly reduced amount of MDP-1 deposition in tissues that normally undergo morphogenetic cell death. This suggests a regulatory role for apoptosis in the terminal differentiation of Drosophila hemocytes. MDP-1 is initially deposited around the developing central nervous system and is later found in basement membrane structures surrounding various other organs, such as the gut, Malpighian tubules and part of the tracheal system. The temporal and localized deposition of MDP-1 suggests that it may play a role in delineating the central nervous system structure during axonogenesis and may participate in the formation of a functional 'blood-brain barrier' in Drosophila.
我们使用一种新型单克隆抗体研究了果蝇胚胎中一种大型蛋白聚糖型分子的表达。这种分子仅由迁移性胚胎血细胞/巨噬细胞分泌，因此被命名为MDP-1，即巨噬细胞衍生蛋白聚糖-1。MDP-1的表达在血细胞分化后期开始，此时这些细胞已离开其在头部中胚层的出生地。此时，巨噬细胞参与细胞外基质沉积以及胚胎各部位凋亡事件产生的细胞碎片的吞噬作用，特别是来自发育中的中枢神经系统的细胞碎片。缺乏程序性细胞死亡的胚胎在通常经历形态发生性细胞死亡的组织中显示出大量减少的MDP-1沉积。这表明凋亡在果蝇血细胞的终末分化中起调节作用。MDP-1最初沉积在发育中的中枢神经系统周围，随后在围绕其他各种器官（如肠道、马氏管和气管系统的一部分）的基底膜结构中发现。MDP-1的时间和局部沉积表明，它可能在轴突发生过程中描绘中枢神经系统结构方面发挥作用，并可能参与果蝇功能性“血脑屏障”的形成。
