Patel Sonal, Overgård Aina-Cathrine, Nerland Audun Helge
Institute of Marine Research, Nordnesgate 50, Postboks 1870 Nordnes, N-5817 Bergen, Norway.
Fish Shellfish Immunol. 2008 Nov;25(5):570-80. doi: 10.1016/j.fsi.2008.08.007. Epub 2008 Aug 29.
CD8 is expressed on cytotoxic T-cells where it functions as a co-receptor for the TCR by binding to MHC class I proteins that present peptides on the cell surface. In this study we describe the cloning and sequencing of full length cDNAs encoding CD8alpha and CD8beta from Atlantic halibut (Hippoglossus hippoglossus L.) and subsequent isolation and characterization of the CD8alpha and CD8beta genes. The predicted halibut CD8alpha and CD8beta proteins are similar to those of mammals and other fish. Real time RT-PCR revealed that the highest levels of CD8 mRNA were found in the thymus, while some expression was also seen in the spleen, the gills, and the anterior and posterior kidney. In situ hybridization confirmed that the halibut thymus contained numerous CD8alpha and CD8beta expressing cells, while the anterior kidney had no CD8alpha positive cells but only a few CD8beta expressing cells. Only moderate changes in CD8 mRNA expression in other organs during either nodavirus or Vibrio anguillarum infection were observed. Both CD8alpha and CD8beta were significantly (P<0.05) down-regulated in spleen at 48h compared to their levels at 12h post-infection with nodavirus and V. anguillarum.
CD8在细胞毒性T细胞上表达，通过与在细胞表面呈递肽段的MHC I类蛋白结合，它作为TCR的共受体发挥作用。在本研究中，我们描述了来自大西洋庸鲽（Hippoglossus hippoglossus L.）的编码CD8α和CD8β的全长cDNA的克隆和测序，以及随后CD8α和CD8β基因的分离和鉴定。预测的庸鲽CD8α和CD8β蛋白与哺乳动物和其他鱼类的相似。实时RT-PCR显示，CD8 mRNA在胸腺中的水平最高，而在脾脏、鳃以及前肾和后肾中也有一些表达。原位杂交证实，庸鲽胸腺含有大量表达CD8α和CD8β的细胞，而前肾没有CD8α阳性细胞，只有少数表达CD8β的细胞。在诺达病毒或鳗弧菌感染期间，观察到其他器官中CD8 mRNA表达只有适度变化。与感染诺达病毒和鳗弧菌后12小时的水平相比，在48小时时，脾脏中的CD8α和CD8β均显著下调（P<0.05）。
