Mao Yuting, Furukawa Seiichi
Degree Programs in Life and Earth Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Insect Sci. 2025 Jun;32(3):845-860. doi: 10.1111/1744-7917.13432. Epub 2024 Aug 12.
Insect hemocytes eliminate foreign substances from the hemocoel through various immune reactions. Integrins, receptor proteins present on the cell membrane, are formed as a heterodimer from α and β subunits and are known to be involved in various immune reactions. To elucidate the role of integrins in the immunity of the lepidoptera Mythimna separata, genes encoding integrins were screened from the genome, resulting in the identification of eight α and four β integrin genes. The expression levels of the integrin genes did not change in response to the injection of small abiotic beads undergoing phagocytosis in M. separata larvae. However, significant inductions of some integrin gene expressions were observed in hemocytes that formed capsules around large abiotic beads during encapsulation, especially in MysIntα2. Under biotic stimulation, induction of the MysIntα2 was evident after exposures to Gram-negative bacteria (Escherichia coli) and entomopathogenic nematodes (Steinernema carpocapsae), but not to Gram-positive bacteria (Micrococcus luteus). Immunostaining analysis revealed that MysIntα2 was specifically localized to hemocytes surrounding the beads during the encapsulation reaction. Furthermore, the spreading and encapsulation abilities of hemocytes were significantly inhibited by incubation with MysIntα2 antibodies. Suppression of MysIntα2 expression in M. separata larvae by injecting double-stranded RNA also resulted in a decrease in encapsulation activity. Collectively, these results indicate that MysIntα2 plays pivotal roles in the cellular immune response of M. separata, particularly during encapsulation. This likely occurs through the regulation of hemocyte spreading activity, thereby facilitating the formation of multilayered capsules around large invaders.
昆虫血细胞通过各种免疫反应从血腔中清除异物。整合素是存在于细胞膜上的受体蛋白，由α和β亚基形成异二聚体，已知参与各种免疫反应。为了阐明整合素在鳞翅目粘虫免疫中的作用，从基因组中筛选了编码整合素的基因，鉴定出8个α整合素基因和4个β整合素基因。在粘虫幼虫中，注射正在被吞噬的小非生物珠后，整合素基因的表达水平没有变化。然而，在包囊形成过程中，围绕大非生物珠形成包囊的血细胞中观察到一些整合素基因表达的显著诱导，尤其是在MysIntα2中。在生物刺激下，暴露于革兰氏阴性菌（大肠杆菌）和昆虫病原线虫（小卷蛾斯氏线虫）后，MysIntα2的诱导明显，但暴露于革兰氏阳性菌（藤黄微球菌）后则不明显。免疫染色分析表明，在包囊反应过程中，MysIntα2特异性定位于围绕珠子的血细胞中。此外，用MysIntα2抗体孵育可显著抑制血细胞的铺展和包囊能力。通过注射双链RNA抑制粘虫幼虫中MysIntα2的表达也导致包囊活性降低。总体而言，这些结果表明MysIntα2在粘虫的细胞免疫反应中起关键作用，尤其是在包囊形成过程中。这可能是通过调节血细胞铺展活性来实现的，从而促进围绕大型入侵者形成多层包囊。
