Subramaniam M, Hefferan T E, Tau K, Peus D, Pittelkow M, Jalal S, Riggs B L, Roche P, Spelsberg T C
Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA.
J Cell Biochem. 1998 Feb 1;68(2):226-36.
This laboratory has previously identified a novel TGF-beta inducible early gene (TIEG) in human osteoblasts [Subramaniam et al. (1995): Nucleic Acids Res 23:4907-4912]. Using TIEG specific polyclonal antibody and immunoprecipitation methods in normal human fetal osteoblast cells (hFOB cells), we have now demonstrated that TIEG encodes a 72-kDa protein whose levels are transiently increased at as early as 2 h of TGF-beta treatment. Polarized confocal microscopic analysis of hFOB cells shows a nuclear localized TIEG protein in untreated cells under the conditions described under Methods. Interestingly, the levels of TIEG protein in the nuclei increase when the cells are treated with TGF-beta 1 for 2 h. In contrast, similar analyses of untreated human keratinocytes show a cytoplasmic localized TIEG protein that appears to be translocated to the nucleus after H2O2 treatment. Additional immunohistochemical studies have demonstrated that TIEG protein is expressed in epithelial cells of the placenta, breast, and pancreas, as well as in osteoblast cells of bone and selected other cells of the bone marrow and cerebellum with some cells showing a cytoplasmic localization and others a nuclear localization. All cells of the kidney display negative staining for this protein. Interestingly, a stage specific expression of TIEG protein is found in a dozen breast cancer biopsies, using immunohistochemistry. The cells in normal breast epithelium displays a high expression of TIEG protein, those in the in situ carcinoma display less than one-half of the levels, and those in the invasive carcinoma show a complete absence of the TIEG protein. TIEG has been localized to chromosome 8q22.2 locus, the same locus as the genes involved in osteopetrosis and acute myeloid leukemia and close to the c-myc gene locus and a locus of high polymorphism in cancer biopsies. The correlation between the levels of TIEG protein and the stage of breast cancer, its prime location in human chromosome 8q22.2, and past studies with pancreatic carcinoma, suggests that TIEG may play a role in tumor suppressor gene activities, apoptosis, or some other regulatory function of cell cycle regulation.
本实验室先前已在人成骨细胞中鉴定出一种新型的转化生长因子β诱导早期基因（TIEG）[Subramaniam等人（1995年）：《核酸研究》23:4907 - 4912]。在正常人胎儿成骨细胞（hFOB细胞）中使用TIEG特异性多克隆抗体和免疫沉淀方法，我们现在已证明TIEG编码一种72 kDa的蛋白质，其水平在转化生长因子β处理后最早2小时就会短暂升高。在方法部分所述条件下，对hFOB细胞进行偏振共聚焦显微镜分析显示，未处理细胞中的TIEG蛋白定位于细胞核。有趣的是，当细胞用转化生长因子β1处理2小时后，细胞核中TIEG蛋白的水平会增加。相比之下，对未处理的人角质形成细胞进行类似分析显示，TIEG蛋白定位于细胞质，在过氧化氢处理后似乎会转运到细胞核。额外的免疫组织化学研究表明，TIEG蛋白在胎盘、乳腺和胰腺的上皮细胞中表达，以及在骨的成骨细胞和骨髓及小脑的某些其他细胞中表达，一些细胞显示细胞质定位，另一些细胞显示细胞核定位。肾脏的所有细胞对该蛋白呈阴性染色。有趣的是，使用免疫组织化学方法在十几例乳腺癌活检中发现了TIEG蛋白的阶段特异性表达。正常乳腺上皮中的细胞显示TIEG蛋白高表达，原位癌中的细胞显示的水平不到正常水平的一半，而浸润癌中的细胞则完全没有TIEG蛋白。TIEG已定位到8号染色体q22.2位点，该位点与涉及骨硬化症和急性髓性白血病的基因相同，且靠近c - myc基因位点以及癌症活检中高度多态性的一个位点。TIEG蛋白水平与乳腺癌阶段之间的相关性、其在人8号染色体q22.2上的主要定位以及过去对胰腺癌的研究表明，TIEG可能在肿瘤抑制基因活性、细胞凋亡或细胞周期调控的某些其他调节功能中发挥作用。
