School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China.
Fish Shellfish Immunol. 2010 Dec;29(6):998-1002. doi: 10.1016/j.fsi.2010.08.010. Epub 2010 Aug 20.
Epithelial cell adhesion molecule (EpCAM) was initially identified as a tumor-associated antigen in human. Recent studies show that EpCAM is a transmembrane glycoprotein with diverse functions in cell adhesion and other processes such as cellular signaling, cell migration, proliferation and differentiation. In fish, the knowledge on the structure and function of EpCAM is limited as only zebrafish EpCAM has been characterized and shown to play a role in embryonic development. In the present study, we isolated a cDNA encoding a homologue of zebrafish EpCAM from grass carp. The deduced grass carp EpCAM (gcEpCAM) protein of 306 amino acids shared 59-85% of similarity with the EpCAMs in other vertebrates. Protein sequence analysis revealed a transmembrane domain and two epidermal growth factor (EGF)-like repeats in the extracellular region of gcEpCAM which were both conserved in EpCAM from fish to mammal. RT-PCR analysis showed that gcEpCAM transcript was expressed with high abundance in skin, pituitary, kidney, head kidney, gill, thymus and head kidney leucocyte (HKL). Furthermore, real time PCR assay was developed to assess gcEpCAM mRNA expression in HKLs stimulated by lipopolysaccharide (LPS). Results showed that LPS significantly increased gcEpCAM mRNA expression in a time- and dose-dependent manner and the peak response was observed at 12h after treatment with 30 μg/ml of LPS. These results indicated that gcEpCAM may be a LPS-induced gene involved in the immune response in fish head kidney.
上皮细胞黏附分子（EpCAM）最初被鉴定为人源肿瘤相关抗原。最近的研究表明，EpCAM 是一种跨膜糖蛋白，在细胞黏附以及细胞信号转导、细胞迁移、增殖和分化等过程中具有多种功能。在鱼类中，EpCAM 的结构和功能的相关知识较为有限，目前仅鉴定和研究了斑马鱼 EpCAM，发现其在胚胎发育中发挥作用。本研究从草鱼中分离到一个编码斑马鱼 EpCAM 同源物的 cDNA。草鱼 EpCAM（gcEpCAM）蛋白由 306 个氨基酸组成，与其他脊椎动物的 EpCAM 具有 59-85%的相似性。蛋白序列分析显示 gcEpCAM 的跨膜结构域和两个表皮生长因子（EGF）样重复序列位于其胞外区，这些序列在鱼类到哺乳动物的 EpCAM 中均具有保守性。RT-PCR 分析表明 gcEpCAM 转录本在皮肤、脑垂体、肾脏、头肾、鳃、胸腺和头肾白细胞（HKL）中大量表达。此外，建立了实时 PCR 检测方法来评估 LPS 刺激的 HKL 中 gcEpCAM mRNA 的表达。结果表明，gcEpCAM mRNA 的表达随 LPS 刺激时间和剂量的增加而呈时间和剂量依赖性增加，在 LPS 处理 30μg/ml 后 12h 达到峰值。这些结果表明 gcEpCAM 可能是一种 LPS 诱导的参与鱼类头肾免疫反应的基因。
