Yao Ying, Wei Honglan, Liu Lili, Liu Lin, Bai Shoujun, Li Caixia, Luo Yun, Zeng Rui, Han Min, Ge Shuwang, Xu Gang
Department of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
J Huazhong Univ Sci Technolog Med Sci. 2011 Aug;31(4):469. doi: 10.1007/s11596-011-0475-3. Epub 2011 Aug 7.
Recently, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is suggested as a new agent in the fighting against fibrogenesis. In tumor, DJ-1 is identified as a negative regulator of PTEN. But the expression of DJ-1 and the regulation of PTEN in fibrosis are unclear. Renal fibrosis was induced in 5/6 subtotal nephrectomy rat model. Human proximal tubular epithelial cells (HKC) were treated with transforming growth factor-beta 1 (TGF-β1), or transfected with DJ-1 or PTEN. Confocal microscope was used to investigate the localization of DJ-1 and PTEN. The selective phosphoinositide-3 kinase (PI3K) inhibitor, LY294002, was administered to inhibit PI3K pathway. The DJ-1 and PTEN expression, markers of epithelial-mesenchymal transition (EMT) and Akt phosphorylation were measured by RT-PCR, Western blotting or immunocytochemistry. In vitro, after HKC cells were stimulated with 10 ng/mL TGF-β1 for 72 h, the expression of DJ-1 was increased, and that of PTEN was decreased. In vivo, the same results were identified in 5/6-nephrectomized rats. In normal HKC cells, most of DJ-1 protein localized in cytoplasm, and little in nucleus. TGF-β1 upregulated DJ-1 expression in both cytoplasma and nuclei. In contrary, TGF-β1 emptied cytoplasmic PTEN protein into nucleus. Overexpression of DJ-1 decreased the expression of PTEN, promoted the activation of Akt and the expression of vimentin, and also led to the loss of cytoplasmic PTEN. Contrarily, overexpression of PTEN protected HKC cells from TGF-β1-induced EMT. In conclusion, DJ-1 is upregulated in renal fibrosis and DJ-1 mediates EMT by suppressing cytoplasmic PTEN expression and Akt activation.
最近，10号染色体缺失的磷酸酶和张力蛋白同源物（PTEN）被认为是对抗纤维化的一种新因子。在肿瘤中，DJ-1被鉴定为PTEN的负调节因子。但DJ-1在纤维化中的表达及对PTEN的调节尚不清楚。采用5/6肾大部切除大鼠模型诱导肾纤维化。用转化生长因子-β1（TGF-β1）处理人近端肾小管上皮细胞（HKC），或转染DJ-1或PTEN。用共聚焦显微镜研究DJ-1和PTEN的定位。给予选择性磷酸肌醇-3激酶（PI3K）抑制剂LY294002抑制PI3K通路。通过RT-PCR、蛋白质免疫印迹或免疫细胞化学检测DJ-1和PTEN的表达、上皮-间质转化（EMT）标志物及Akt磷酸化。体外实验中，HKC细胞用10 ng/mL TGF-β1刺激72小时后，DJ-1表达增加，PTEN表达降低。体内实验中，5/6肾切除大鼠也得到相同结果。在正常HKC细胞中，大部分DJ-1蛋白定位于细胞质，细胞核中较少。TGF-β1使DJ-1在细胞质和细胞核中的表达均上调。相反，TGF-β1将细胞质中的PTEN蛋白转移至细胞核。DJ-1过表达降低了PTEN的表达，促进了Akt的激活和波形蛋白的表达，也导致细胞质中PTEN的丢失。相反，PTEN过表达可保护HKC细胞免受TGF-β1诱导的EMT。总之，DJ-1在肾纤维化中上调，且DJ-1通过抑制细胞质PTEN表达和Akt激活介导EMT。
