血管内皮细胞MICA基因mRNA和蛋白质表达

Expression of MICA mRNA and Protein in Human Endothelial Cells

MICA系MHC-I类相关多态性基因A,其表达细胞膜蛋白质分子与器官移植免疫排斥有关.新生儿脐带静脉血管内皮细胞(HUVEC)被分离和培养至4～6代.11例新分离培养的HUVEC和7种人细胞株的MICAmRNA转录水平用RT-PCR检测,应用细胞流式检测细胞膜表面的MICA分子的表达情况,同时应用免疫印迹的方法对整个细胞MICA蛋白质的表达水平进行检测和分析.结果显示MICAmRNA在所有检测细胞中有表达,HUVEC细胞膜或胞浆中MICA蛋白质表达量很高,而在人体淋巴细胞膜表面和胞内未检出MICA分子的表达.提示HUVEC和淋巴细胞在MICA表达的差异性可能与不同细胞的内部调节机制有关.而供体器官血管内皮细胞表达多态性MICA分子有可能成为移植抗原发生免疫排斥反应.

MHC class I related Chain A（MICA）is a polymorphic gene that expresses glycoproteins on the cellular membrane.It may play a role in organ transplant rejection.Human umbilical vein endothelial cells（HUVEC）were isolated from umbilical cord veins and cultured within 4~6 passages.RT-PCR was used to analyze MICA mRNA that expressed on 11 HUEVCs and 7 culture cell lines.Surface MICA expression was examined by flow cytometry with monoclonal antibody staining.Total MICA proteins were accessed by Western blot.The results show that all of tested cells were found to have MICA mRNA expression.HUEVCs have surface MICA expressed in high level,but MICA protein expression in T and B lymphocytes was not detected.The difference of MICA expression by human endothelial cells and lymphocytes may indicate that the levels of surface MICA are differentially regulated in different cells.Moreover,the expression of MICA on the surface of endothelial cells makes this polymorphic molecule a possible target during the immune response of graft rejection in organ transplantation.