Lee Kwang Sik, Kim Bo Yeon, Choo Young Moo, Jin Byung Rae
Department of Applied Biology, College of Natural Resources and Life Science, Dong-A University, Busan, 604-714, Republic of Korea.
Department of Applied Biology, College of Natural Resources and Life Science, Dong-A University, Busan, 604-714, Republic of Korea.
Dev Comp Immunol. 2018 Aug;85:170-176. doi: 10.1016/j.dci.2018.04.011. Epub 2018 Apr 11.
Serine proteases and serine protease homologs are involved in the prophenoloxidase (proPO)-activating system leading to melanization. The Bombyx mori serine protease homolog BmSPH-1 regulates nodule melanization. Here, we show the dual role of BmSPH-1 in the development and immunity of B. mori. BmSPH-1 was expressed in hemocytes after molting and during the larval-pupal transformation in normal development. In contrast, following infection, BmSPH-1 was expressed in hemocytes and cleaved in the hemolymph, which resulted in the induction of PO activity. Moreover, BmSPH-1 was cleaved in the cuticle during the larval-pupal transformation and early pupal stages. In BmSPH-1 RNAi-treated silkworms, the reduced BmSPH-1 mRNA levels during the spinning stage or the prepupal stage resulted in the arrest of pupation or pupal cuticular melanization, respectively. The binding assays revealed that BmSPH-1 interacts with B. mori immulectin, proPO, and proPO-activating enzyme. Our findings demonstrate that BmSPH-1 paticipates larval-pupal transformation, pupal cuticular melanization and innate immunity of silkworms, illustrating the dual role of BmSPH-1 in development and immunity.
丝氨酸蛋白酶和丝氨酸蛋白酶同源物参与导致黑化的前酚氧化酶（proPO）激活系统。家蚕丝氨酸蛋白酶同源物BmSPH-1调节结节黑化。在此，我们展示了BmSPH-1在家蚕发育和免疫中的双重作用。在正常发育过程中，BmSPH-1在蜕皮后和幼虫-蛹转化期间在血细胞中表达。相比之下，感染后，BmSPH-1在血细胞中表达并在血淋巴中被切割，这导致了PO活性的诱导。此外，在幼虫-蛹转化和蛹早期阶段，BmSPH-1在表皮中被切割。在经BmSPH-1 RNA干扰处理的家蚕中，吐丝阶段或预蛹阶段BmSPH-1 mRNA水平降低分别导致化蛹停滞或蛹表皮黑化。结合试验表明，BmSPH-1与家蚕免疫凝集素、proPO和proPO激活酶相互作用。我们的研究结果表明，BmSPH-1参与家蚕的幼虫-蛹转化、蛹表皮黑化和先天免疫，说明了BmSPH-1在发育和免疫中的双重作用。
