Zhang Z, Cohen D M
Division of Nephrology, Hypertension, and Clinical Pharmacology, Oregon Health Sciences University, Portland, USA.
Am J Physiol. 1997 Nov;273(5):F837-42. doi: 10.1152/ajprenal.1997.273.5.F837.
In cells of the murine renal inner medullary collecting duct (mIMCD3) cell line, acute hypotonic shock (50% dilution of medium with sterile water but not with sterile 150 mM NaCl) increased Egr-1 mRNA abundance 2.5-fold at 6 h, as determined by Northern analysis. This increase was accompanied by increased Egr-1 transcription, as quantitated by luciferase reporter gene assay. Increased transcription was dose dependent, additive with other Egr-1 transcriptional activators, and occurred in the absence of overt cytotoxicity, as quantitated via a fluorometric viability assay. In addition, hypotonic stress increased Egr-1 protein abundance, which was accompanied by augmented Egr-1-specific DNA binding ability, as measured via electrophoretic mobility shift assay. Increased DNA binding was further associated with increased transactivation by Egr-1, demonstrated through transient transfection of mIMCD3 cells with a luciferase reporter gene driven by tandem repeats of the Egr-1 DNA consensus sequence. Taken together, these data indicate that hypotonic stress activates Egr-1 transcription, translation, DNA binding, and transactivation in renal medullary cells. This phenomenon might play a role in the acquisition of the adaptive phenotype in response to hypotonic stress in cells of the renal medulla in vivo.
在小鼠肾内髓集合管（mIMCD3）细胞系的细胞中，急性低渗休克（用无菌水而非无菌150 mM NaCl将培养基稀释50%）使Egr-1 mRNA丰度在6小时时增加了2.5倍，这是通过Northern分析确定的。这种增加伴随着Egr-1转录的增加，通过荧光素酶报告基因测定进行定量。转录增加呈剂量依赖性，与其他Egr-1转录激活剂相加，并且在没有明显细胞毒性的情况下发生，通过荧光活力测定进行定量。此外，低渗应激增加了Egr-1蛋白丰度，同时伴随着Egr-1特异性DNA结合能力的增强，通过电泳迁移率变动分析进行测量。DNA结合增加进一步与Egr-1的反式激活增加相关，通过用由Egr-1 DNA共有序列串联重复驱动的荧光素酶报告基因对mIMCD3细胞进行瞬时转染来证明。综上所述，这些数据表明低渗应激激活了肾髓质细胞中Egr-1的转录、翻译、DNA结合和反式激活。这种现象可能在体内肾髓质细胞对低渗应激的适应性表型获得中发挥作用。
