Ren Chunhua, Chen Ting, Jiang Xiao, Luo Xing, Wang Yanhong, Hu Chaoqun
CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Key Laboratory of Applied Marine Biology of Guangdong Province and Chinese Academy of Sciences (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China.
Fish Shellfish Immunol. 2015 Jan;42(1):41-9. doi: 10.1016/j.fsi.2014.10.024. Epub 2014 Oct 28.
Gamma-interferon-inducible lysosomal thiol reductase (GILT) has been described as a key enzyme that facilitating the processing and presentation of major histocompatibility complex class II-restricted antigen in mammals. In this study, the first echinoderm GILT named StmGILT was identified from sea cucumber (Stichopus monotuberculatus). The StmGILT cDNA is 1529 bp in length, containing a 5'-untranslated region (UTR) of 87 bp, a 3'-UTR of 674 bp and an open reading frame (ORF) of 768 bp that encoding a protein of 255 amino acids with a deduced molecular weight of 27.82 kDa and a predicted isoelectric point of 4.73. The putative StmGILT protein possesses all the main characteristics of known GILT proteins, including a signature sequence, a reductase active site CXXC, twelve conserved cysteines, and two potential N-linked glycosylation sites. For the gene structure, StmGILT contains four exons separated by three introns. In the promoter region of StmGILT gene, an NF-κB binding site and an IFN-γ activation site were found. The thiol reductase activity of recombinant StmGILT protein was also demonstrated in this study. In addition, the highest level of mRNA expression was noticed in coelomocytes of S. monotuberculatus. In in vitro experiments performed in coelomocytes, the expression of StmGILT mRNA was significantly up-regulated by lipopolysaccharides (LPS), inactivated bacteria or polyriboinosinic polyribocytidylic acid [poly (I:C)] challenge, suggested that the sea cucumber GILT might play critical roles in the innate immune defending against bacterial and viral infections.
γ-干扰素诱导的溶酶体巯基还原酶（GILT）被描述为一种关键酶，它有助于在哺乳动物中加工和呈递主要组织相容性复合体II类限制性抗原。在本研究中，从海参（单环刺螠）中鉴定出首个棘皮动物GILT，命名为StmGILT。StmGILT cDNA长度为1529 bp，包含一个87 bp的5'-非翻译区（UTR）、一个674 bp的3'-UTR和一个768 bp的开放阅读框（ORF），该开放阅读框编码一个255个氨基酸的蛋白质，推导分子量为27.82 kDa，预测等电点为4.73。推测的StmGILT蛋白具有已知GILT蛋白的所有主要特征，包括一个特征序列、一个还原酶活性位点CXXC、十二个保守的半胱氨酸和两个潜在的N-糖基化位点。关于基因结构，StmGILT包含四个外显子，由三个内含子隔开。在StmGILT基因的启动子区域，发现了一个NF-κB结合位点和一个IFN-γ激活位点。本研究还证实了重组StmGILT蛋白的巯基还原酶活性。此外，在单环刺螠的体腔细胞中观察到最高水平的mRNA表达。在体腔细胞中进行的体外实验中，脂多糖（LPS）、热灭活细菌或聚肌苷酸-聚胞苷酸[poly（I:C）]刺激显著上调了StmGILT mRNA的表达，这表明海参GILT可能在抵御细菌和病毒感染的先天免疫中发挥关键作用。
