Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Qingdao Key Laboratory for Marine Fish Breeding and Biotechnology, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Dev Comp Immunol. 2020 Jul;108:103686. doi: 10.1016/j.dci.2020.103686. Epub 2020 Mar 20.
A robust immune response against invading pathogens greatly depends on the balance of metabolism, which could be vigorously modulated by insulin/IGF signaling (IIS) pathway in vertebrates. However, knowledge on the IIS pathway, especially the function of insulin-like peptides (ILPs) in invertebrates remained largely unknown. In the present study, a novel ILP was identified from Eriocheir sinensisis (designated EsILP). The coding sequence of EsILP was of 216 bp, which encoded a polypeptide of 71 amino acids containing an IlGF-like domain with four conserved cysteine residues. The mRNA transcripts of EsILP were found to be expressed dominantly in eyestalks and hepatopancreas, and EsILP protein was found to be distributed in the anterior median area of thoracic ganglion mass and the edges of hepatic tubules correspondingly. After Aeromonas hydrophila stimulation, EsILP transcripts were significantly increased at 3, 12 and 24 h post-stimulation in eyestalks and 6 and 48 h in hemocytes, respectively. In contrast, the expression level of EsILP decreased significantly in hepatopancreas from 6 h to 12 h after the stimulation. The glucose level in the hemolymph of crabs was significantly decreased from 6 to 12 h after the injection of recombinant EsILP. These results collectively demonstrated that the ancient ILP protein in E. sinensisis could negatively regulate glucose metabolism and participate in the immune response of the crabs against pathogen infection, which provided clues for the further investigation about the evolution and function of the IIS pathway in invertebrates.
一个强大的免疫反应对抗入侵病原体在很大程度上取决于新陈代谢的平衡，这可以通过脊椎动物的胰岛素/IGF 信号通路（IIS）强有力地调节。然而，关于 IIS 通路的知识，特别是胰岛素样肽（ILPs）在无脊椎动物中的功能，仍然知之甚少。在本研究中，从中华绒螯蟹（命名为 EsILP）中鉴定出一种新型的 ILP。EsILP 的编码序列为 216bp，编码一个 71 个氨基酸的多肽，含有一个具有四个保守半胱氨酸残基的 IlGF 样结构域。发现 EsILP 的 mRNA 转录物主要在眼柄和肝胰腺中表达，EsILP 蛋白则分布在前胸神经节质量的前正中区和肝小管的边缘。在受到嗜水气单胞菌刺激后，EsILP 转录物在眼柄中分别在刺激后 3、12 和 24h 显著增加，在血细胞中在 6 和 48h 显著增加。相比之下，在刺激后 6-12h，EsILP 在肝胰腺中的表达水平显著降低。注射重组 EsILP 后，螃蟹血淋巴中的葡萄糖水平从 6 小时到 12 小时显著下降。这些结果共同表明，中华绒螯蟹中古老的 ILP 蛋白可以负调控葡萄糖代谢，并参与螃蟹对病原体感染的免疫反应，为进一步研究 IIS 通路在无脊椎动物中的进化和功能提供了线索。
