College of Life Sciences, Liaoning Normal University, Dalian, 116081, China; Lamprey Research Center, Liaoning Normal University, Dalian, 116081, China.
Fish Shellfish Immunol. 2019 Sep;92:196-208. doi: 10.1016/j.fsi.2019.05.062. Epub 2019 Jun 5.
Serine protease inhibitors (serpins) are a large protein family that is involved in various physiological processes and is known to regulate innate immunity pathways. However, research for the functional study of serpins in lamprey is limited. In the present study, a serpin gene was cloned and characterized from Lampetra japonica at molecular, protein and cellular levels, named L-serpin which belongs to family F serine protease inhibitors (serpin family). The L-serpin includes a serpin domain in the N-terminus. The mRNA transcript of L-serpin was extensively expressed in kidney, supraneural body, intestine, liver, heart, gill and the highest expression in leukocytes. The mRNA expression level of L-serpin increased significantly after Vibrio anguillarum, Staphylocccus aureus and Poly I:C stimulation and dramatically peak at 8 h. It is demonstrated that the L-serpin protected cells from lethal Gram-negative endotoxemia through associating with inhibition of lipopolysaccharide (LPS)-triggered cell death and inflammatory factors expression. Surface plasmon resonance (SPR) and the microbe binding assay were used to determine that L-serpin interacts directly with LPS (KD = 6.14 × 10 M). Furthermore, we confirmed L-serpin is a major inhibitor of complement activation by inactivating lamprey-C1q protein (KD = 2.06 × 10 M). Taken together, these findings suggest that L-serpin is a endogenous anti-inflammatory factor to defend against Gram-negative bacterial challenge and involved in lamprey innate immunity.
丝氨酸蛋白酶抑制剂（serpins）是一个庞大的蛋白质家族，参与多种生理过程，并且已知可调节先天免疫途径。然而，关于七鳃鳗 serpins 的功能研究还很有限。本研究从日本七鳃鳗中克隆和鉴定了一种丝氨酸蛋白酶抑制剂（serpin 家族）基因，命名为 L-serpin。L-serpin 在 N 端包含一个 serpin 结构域。L-serpin 的 mRNA 转录本在肾脏、神经上体、肠、肝、心脏、鳃中广泛表达，在白细胞中表达量最高。L-serpin 的 mRNA 表达水平在鳗弧菌、金黄色葡萄球菌和 Poly I:C 刺激后显著增加，在 8 小时达到峰值。研究表明，L-serpin 通过与脂多糖（LPS）触发的细胞死亡和炎症因子表达抑制相关，从而保护细胞免受致命的革兰氏阴性内毒素血症的影响。表面等离子体共振（SPR）和微生物结合测定表明，L-serpin 与 LPS 直接相互作用（KD=6.14×10-7M）。此外，我们还证实 L-serpin 通过失活七鳃鳗-C1q 蛋白来抑制补体激活（KD=2.06×10-7M）。综上所述，这些发现表明 L-serpin 是一种内源性抗炎因子，可抵御革兰氏阴性细菌的挑战，并参与七鳃鳗的先天免疫。
