Thulasitha William Shanthakumar, Kim Yucheol, Umasuthan Navaneethaiyer, Jayasooriya R G P T, Kim Gi-Young, Nam Bo-Hye, Noh Jae Koo, Lee Jehee
Department of Marine Life Sciences, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
Department of Marine Life Sciences, Jeju National University, Jeju Self-Governing Province, 63243, Republic of Korea.
Fish Shellfish Immunol. 2016 Jul;54:11-21. doi: 10.1016/j.fsi.2016.03.154. Epub 2016 Mar 26.
Thioredoxin domain-containing protein 12 (TXNDC12) is a small, disulfide-containing protein that belongs to the thioredoxin (TXN) superfamily. In the present study, we identified and characterized a TXNDC12-like gene, designated OfTXNDC12, from rock bream, Oplegnathus fasciatus. OfTXNDC12 consists of seven exons interrupted by six introns. Comparative genomic structural analysis revealed that the TXNDC12 of vertebrates is a structurally conserved gene. The coding sequence of OfTXNDC12 comprises 522 bp, which encodes 173 amino acid residues with the conserved thioredoxin active site motif, CGAC, and a probable C-terminal ER retrieval motif, GDEL. Transcriptional analysis of OfTXNDC12 showed the highest concentrations of the mRNA transcript in the liver, implying that it has a significant role in the liver under normal physiological conditions. In comparison, injection of lipopolysaccharide, Edwardsiella tarda, Streptococcus iniae, polyinosinic:polycytidylic acid (poly[I:C]) and rock bream iridovirus mostly triggered greater upregulation of OfTXNDC12 transcript levels in liver than in gill tissue, supporting its potential functional importance in the liver. Insulin disulfide reduction assay showed that the recombinant fusion protein (rOfTXNDC12) possesses significant thioredoxin activity. Treatment of LNCaP cells with the recombinant protein along with H2O2 revealed that rOfTXNDC12 increased the viability of cells and further supported its putative antioxidant capacity. Taken together, the results from our study suggest that OfTXNDC12 encodes for a potent antioxidant involved in redox regulation that shows significant responses to immune stimuli.
含硫氧还蛋白结构域蛋白12（TXNDC12）是一种小型的含二硫键蛋白，属于硫氧还蛋白（TXN）超家族。在本研究中，我们从条石鲷（Oplegnathus fasciatus）中鉴定并表征了一个类似TXNDC12的基因，命名为OfTXNDC12。OfTXNDC12由7个外显子组成，被6个内含子隔开。比较基因组结构分析表明，脊椎动物的TXNDC12是一个结构保守的基因。OfTXNDC12的编码序列包含522 bp，编码173个氨基酸残基，具有保守的硫氧还蛋白活性位点基序CGAC和一个可能的C端内质网回收基序GDEL。OfTXNDC12的转录分析表明，mRNA转录本在肝脏中的浓度最高，这意味着它在正常生理条件下的肝脏中具有重要作用。相比之下，注射脂多糖、迟缓爱德华氏菌、海豚链球菌、聚肌苷酸:聚胞苷酸（poly[I:C]）和条石鲷虹彩病毒后，肝脏中OfTXNDC12转录水平的上调大多比鳃组织中更明显，这支持了它在肝脏中的潜在功能重要性。胰岛素二硫键还原试验表明，重组融合蛋白（rOfTXNDC12）具有显著的硫氧还蛋白活性。用重组蛋白和H2O2处理LNCaP细胞表明，rOfTXNDC12提高了细胞活力，并进一步支持了其假定的抗氧化能力。综上所述，我们的研究结果表明，OfTXNDC12编码一种参与氧化还原调节的强效抗氧化剂，对免疫刺激有显著反应。
