Cao Hui-Hua, Wang Yu-Ling, Toufeeq Shahzad, Kong Wei-Wei, Ayaz Sadaf, Liu Shi-Huo, Wang Jie, Xu Jia-Ping
Anhui Province Key Laboratory of Resource Insect Biology and Innovative Utilization, School of Life Sciences, Anhui Agricultural University, Hefei 230036, China; School of Bioengineering, Huainan Normal University, Huainan 232038, China.
Anhui Province Key Laboratory of Resource Insect Biology and Innovative Utilization, School of Life Sciences, Anhui Agricultural University, Hefei 230036, China; Anhui International Joint Research and Developmental Center of Sericulture Resources Utilization, Hefei 230036, China.
J Invertebr Pathol. 2024 Nov;207:108188. doi: 10.1016/j.jip.2024.108188. Epub 2024 Sep 6.
A subfamily of conserved proteins called serpins plays crucial roles in various physiological functions, particularly in the activation pathway of the serine protease cascade, an essential component of insect innate immunity. Here, we found Bombyx mori serpin 3 (BmSerpin3) was most highly expressed in the fat body, and was up-regulated after exposure to bacteria, fungus and virus. Further, the expression of BmSerpin3 in the hemocytes, fat body, midgut of silkworm larvae, and BmN cells was up-regulated upon Bombyx mori nucleopolyhedrovirus (BmNPV) infection. Through Bac-to-Bac expression system, we obtained the active protein of BmSerpin3, and the enzyme activity assay showed that BmSerpin3 significantly inhibited the activity of both subtilisin and trypsin. In addition, BmSerpin3 could inhibit the activation of prophenoloxidase (PPO) in larvae. The knockdown of BmSerpin3 showed increased phenoloxidase (PO) activity compared to control after BmNPV infection. Ultimately, we confirmed that BmSerpin3 interacts with B. mori Serine Protease 7 (BmSP7). Hence, we hypothesize that BmSerpin3 is involved in innate immunity by interacting with BmSP7 to regulate the PPO activation cascade. Taken together, these results showed that BmSerpin3 play a role in silkworm innate immunity and lay a foundation for studying its functions.
一个名为丝氨酸蛋白酶抑制剂（serpins）的保守蛋白亚家族在多种生理功能中发挥着关键作用，特别是在丝氨酸蛋白酶级联反应的激活途径中，而丝氨酸蛋白酶级联反应是昆虫先天免疫的重要组成部分。在此，我们发现家蚕丝氨酸蛋白酶抑制剂3（BmSerpin3）在脂肪体中表达量最高，并且在接触细菌、真菌和病毒后会上调。此外，在家蚕核型多角体病毒（BmNPV）感染后，家蚕幼虫的血细胞、脂肪体、中肠以及BmN细胞中BmSerpin3的表达均上调。通过杆状病毒表达系统，我们获得了BmSerpin3的活性蛋白，酶活性测定表明BmSerpin3能显著抑制枯草杆菌蛋白酶和胰蛋白酶的活性。此外，BmSerpin3可以抑制幼虫中酚氧化酶原（PPO）的激活。与对照相比，在BmNPV感染后，敲低BmSerpin3显示酚氧化酶（PO）活性增加。最终，我们证实BmSerpin3与家蚕丝氨酸蛋白酶7（BmSP7）相互作用。因此，我们推测BmSerpin3通过与BmSP7相互作用来调节PPO激活级联反应，从而参与先天免疫。综上所述，这些结果表明BmSerpin3在家蚕先天免疫中发挥作用，为研究其功能奠定了基础。
