Mongan Nigel P, Martin Kisha M, Gudas Lorraine J
Department of Pharmacology, Weill Medical College, Cornell University, New York, New York 10021, USA.
Mol Carcinog. 2006 Dec;45(12):887-900. doi: 10.1002/mc.20186.
Human Rex-1 (hRex-1) (also referred to as zinc-finger protein-42, Zfp42) encodes a zinc finger protein expression of which is believed to be characteristic of pluripotent stem cells. We have applied bioinformatics to classify the relationship of human, rat, and mouse REX1 proteins in the C2H2 family of zinc finger proteins and demonstrate that REX1 is a member of the YY1 sub-family of transcription factors, which includes the Drosophila pleiohomeotic (Pho) protein. We have generated a molecular model of the human REX1 zinc finger domains based on the crystal structure of the YY1 transcription factor. To date, expression of hRex-1 and its extensively studied mouse homolog mRex-1, has been reported only in embryonic and adult stem cells and in differentiated spermatocytes. In this study, reverse transcription-PCR and Western analysis were employed to assay for hRex-1 expression in cultured normal human epithelial cells and human carcinoma cell lines. Expression of hRex-1 mRNA was detected in normal human epidermal keratinocytes, normal prostate epithelial cells (PrEC), bronchial, and small airway lung epithelial cells. Other stem cell markers, such as Oct 4, DAB2, and cMyc were also detected in normal human epidermal keratinocyte cultures. Expression of hRex-1 was also detected in some human tumor cell lines including MDA-MB-468 mammary carcinoma, SCC-15 head and neck squamous cell carcinoma, and N-TERA2 human teratocarcinoma cells. Western analyses confirmed expression of the human REX1 (ZFP42) protein in MDA-MB-468 cells and normal human keratinocytes. This research has identified model human cell culture systems, in addition to embryonic stem (ES) cells, in which Rex-1 is expressed, and this should enable the characterization of REX1 functions in normal adult epithelial cells and tumorigenic stem cells.
人类Rex-1（hRex-1）（也称为锌指蛋白-42，即Zfp42）编码一种锌指蛋白，其表达被认为是多能干细胞的特征。我们应用生物信息学对锌指蛋白C2H2家族中的人类、大鼠和小鼠REX1蛋白的关系进行分类，并证明REX1是转录因子YY1亚家族的成员，该亚家族包括果蝇的多效同源（Pho）蛋白。我们基于YY1转录因子的晶体结构生成了人类REX1锌指结构域的分子模型。迄今为止，hRex-1及其经过广泛研究的小鼠同源物mRex-1仅在胚胎和成人干细胞以及分化的精母细胞中被报道有表达。在本研究中，采用逆转录PCR和蛋白质免疫印迹分析来检测培养的正常人上皮细胞和人癌细胞系中hRex-1的表达。在正常人表皮角质形成细胞、正常前列腺上皮细胞（PrEC）、支气管和小气道肺上皮细胞中检测到了hRex-1 mRNA的表达。在正常人表皮角质形成细胞培养物中还检测到了其他干细胞标志物，如Oct 4、DAB2和cMyc。在一些人类肿瘤细胞系中也检测到了hRex-1的表达，包括MDA-MB-468乳腺癌细胞、SCC-15头颈部鳞状细胞癌细胞和N-TERA2人畸胎瘤细胞。蛋白质免疫印迹分析证实了人类REX1（ZFP42）蛋白在MDA-MB-468细胞和正常人角质形成细胞中的表达。这项研究除了胚胎干细胞外，还鉴定出了表达Rex-1的人类细胞培养模型系统，这将有助于在正常成人上皮细胞和致瘤干细胞中表征REX1的功能。
