Department of Entomology, Soils, and Plant Sciences, Clemson University, Clemson, South Carolina 29634-03 15, USA.
J Insect Sci. 2011;11:6. doi: 10.1673/031.011.0106.
Recent studies have demonstrated that hemichannels, which form gap junctions when paired from apposing cells, may serve additional roles when unpaired including cell adhesion and paracrine communication. Hemichannels in mammals are formed by connexins or pannexins, while in insects they are formed by pannexin homologues termed innexins. The formation of functional gap junctions by insect innexins has been established, although their ability to form functional nonjunctional hemichannels has not been reported. Here the characteristics of nonjunctional hemichannels were examined in three lepidopteran cell types, two cell lines (High Five and Sf9) and explanted hemocytes from Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae). Selective fluorescent dye uptake by hemichannels was observed in a significant minority of cells, using fluorescence microscopy and flow cytometry. Carbenoxelone, an inhibitor of mammalian junctions, disrupted dye uptake, while flufenamic acid and mefloquine did not. The presence of Ca(2+) and Mg(2+) in the media increased hemichannel activity. Additionally, lipopolysaccharide, a stimulator of immune activity in lepidopterans, decreased dye uptake. These results demonstrate for the first time the activity of nonjunctional hemichannels in insect cells, as well as pharmacological tools to manipulate them. These results will facilitate the further examination of the role of innexins and nonjunctional hemichannels in insect cell biology, including paracrine signaling, and comparative studies of mammalian pannexins and insect innexins.
最近的研究表明，半通道在配对细胞形成缝隙连接时可能发挥额外的作用，包括细胞黏附和旁分泌通讯。哺乳动物的半通道由连接蛋白或连接蛋白形成，而昆虫的半通道则由称为连接蛋白同源物的连接蛋白形成。昆虫连接蛋白形成功能性缝隙连接已经得到证实，尽管它们形成功能性非连接性半通道的能力尚未报道。在这里，研究了三种鳞翅目细胞类型（两种细胞系（High Five 和 Sf9）和来自 Heliothis virescens（Fabricius）（鳞翅目：夜蛾科）的离体血细胞）中非连接性半通道的特性。使用荧光显微镜和流式细胞术观察到少数细胞中存在半通道的选择性荧光染料摄取。作为哺乳动物连接体抑制剂的 carbenoxelone 破坏了染料摄取，而 flufenamic acid 和 mefloquine 则没有。培养基中 Ca(2+)和 Mg(2+)的存在增加了半通道的活性。此外，脂多糖，一种刺激鳞翅目免疫活性的物质，减少了染料摄取。这些结果首次证明了昆虫细胞中非连接性半通道的活性，以及用于操纵它们的药理学工具。这些结果将有助于进一步研究连接蛋白和非连接性半通道在昆虫细胞生物学中的作用，包括旁分泌信号传递，以及哺乳动物 pannexin 和昆虫 innexin 的比较研究。
