Bohrmann J, Lämmel H
Institut für Biologie I (Zoologie), Universität Freiburg, Germany.
Int J Dev Biol. 1998 Jul;42(5):709-21.
Ductin is a putative connexon-forming protein in gap junctions of arthropods. To analyze the role of gap-junction mediated cell-cell communication during Drosophila embryogenesis, we used two different polyclonal anti-ductin sera. One antiserum was directed against ductin isolated from gap junctions of the lobster Nephrops whilst the other was raised against a nonapeptide at the N-terminus of ductin from Drosophila. Both antisera were found to inhibit, when microinjected into Drosophila ovarian follicles, the intercellular exchange of fluorescent tracer molecules between oocyte and follicle epithelium. This result indicates that Drosophila ductin plays a decisive role in gap-junctional communication and confirms the cytoplasmic location of the ductin N-terminus in gap junctions. On immunofluorescence preparations and immunoblots, the anti-ductin sera specifically recognized ovarian as well as embryonic antigens. Following microinjections of the antisera into embryos prior to gastrulation, significantly reduced rates of hatching larvae were obtained. Moreover, microinjections into the mid-ventral region of the embryos resulted in specific ventral defects that depended on the concentration of the ductin antibodies. In particular, larvae with ventral holes in their cuticles occurred with high frequency. During gastrulation, antiserum-injected embryos often developed defects in the middle region of their ventral furrow. Here, mesodermal cells failed to invaginate correctly and, thus, no cuticle was formed. We conclude that, during Drosophila embryogenesis, gap-junctional communication is required for epithelial integrity and morphogenetic events.
导管蛋白是节肢动物间隙连接中一种假定的连接子形成蛋白。为了分析间隙连接介导的细胞间通讯在果蝇胚胎发育过程中的作用，我们使用了两种不同的多克隆抗导管蛋白血清。一种抗血清针对从龙虾海螯虾的间隙连接中分离出的导管蛋白，而另一种则是针对果蝇导管蛋白N端的九肽产生的。当将这两种抗血清显微注射到果蝇卵巢卵泡中时，发现它们都能抑制卵母细胞和卵泡上皮细胞之间荧光示踪分子的细胞间交换。这一结果表明果蝇导管蛋白在间隙连接通讯中起决定性作用，并证实了导管蛋白N端在间隙连接中的细胞质定位。在免疫荧光制剂和免疫印迹上，抗导管蛋白血清能特异性识别卵巢和胚胎抗原。在原肠胚形成之前将抗血清显微注射到胚胎中后，孵化出的幼虫数量显著减少。此外，将抗血清显微注射到胚胎的腹中部区域会导致特定的腹部缺陷，这取决于导管蛋白抗体的浓度。特别是，表皮有腹侧孔的幼虫出现频率很高。在原肠胚形成期间，注射抗血清的胚胎在腹沟中部区域常常出现缺陷。在这里，中胚层细胞未能正确内陷，因此没有形成表皮。我们得出结论，在果蝇胚胎发育过程中，间隙连接通讯对于上皮完整性和形态发生事件是必需的。
