Transcriptional regulation of kidney-specific genes

水通道蛋白-2 （aquaporin-2, AQP2）的表达仅局限于肾集管细胞，这种严格的限制性表达可通过该基因的转录介导。AQP2基因5侧区域的特征包括一个TATA盒、两个GATA共识序列、一个AP-1位点、一个AP-2位点、三个e -box和一个循环amp响应元件。在IMCD细胞原代培养第1天进行的报告基因测定表明，-2.9 kb的5'区域起启动子的作用。缺失实验表明，-434 ~ -364和-153 ~ -84至少有两个区域含有负作用的顺式元件。为了评估GATA基序在AQP2基因中的功能作用，我们试图分离一个在集管中表达的GATA因子。从大鼠肾脏中分离到两个编码GATA因子的cdna （GATA-2和-3）。AQP2基因5侧区域的GATA基序为功能性顺式元件，集水管中的GATA-3可能是AQP-2在体内表达的重要调控因子之一。大鼠ic - k1氯离子通道是010氯离子通道家族的肾特异性成员，仅存在于肾Henle’s袢的if-in升肢中。为了深入了解CIC-K1肾特异性表达的机制，我们分离了一个包含大鼠CIC-K1基因5'-侧翼区域的基因组。近5侧区序列包含一个AP-3位点、一个GRE、几个AP-2位点和几个e -box，但缺少一个TATA box。缺失分析显示，这种细胞特异性启动子活性在IM细胞中仍然存在于含有51 bp 5'侧翼区域的结构中，但在-29结构中丢失，这清楚地表明-51至-30的22 bp在cic - k1启动子的细胞特异性活性中起主要作用。这22 bp由富含嘌呤的序列（GGGGAGGGG-GAGGGGAG）组成，凝胶阻滞分析表明，在IM细胞中存在与该元件结合的特定蛋白。这些结果表明，新的富含嘌呤的元素可能在CIC-K1基因启动子的活性中起关键作用。少

Expression of aquaporin-2 (AQP2) is exclusively limited to kidney collecting duct cells, and this strictly limited expression could be mediated by transcription of the gene. The 5-flanking region of the AQP2 gene was characterized by a TATA box, two GATA consensus sequences, an AP-1 site, an AP-2 site, three E-boxes, and a cycle AMP-responsive element. A reporter gene assay performed in the 1st day of primary culture of IMCD cells showed that the 5' region up to -2.9 kb worked as a promoter. Deletion experiments showed that at least two regions, from -434 to -364 and from -153 to -84, contain negatively acting cis-elements. To evaluate the functional role of GATA motifs in AQP2 gene, we sought to isolate a GATA factor(s) expressed in collecting ducts. Two cDNAs encoding GATA factors were isolated from rat kidney (GATA-2 and -3). GATA motifs in the 5-flanking region of the AQP2 gene were functional cis-elements and that GATA-3 in collecting ducts may be one of the important regulators o … More f AQP-2 expression in vivo.The rat CIC-K1 chloride channel is a kidney-specific member of the 010 chloride channel family found exclusively in the if-in ascending limb of Henle's loop in the kidney. To gain insight into the mechanism(s) of kidney-specific expression of CIC-K1, a genomic done that contains the 5'-flanking region of the rat CIC-K1 gene was isolated. The sequence of the proximal 5-flanking region contained an AP-3 site, a GRE, several AP-2 sites, and several E-boxes, but it lacked a TATA box.Deletion analysis revealed that this cell-specific promoter activity in IM cells was still present in the construct containing 51 b p of-the 5'-flanking region but was lost in the -29 construct, dearly demonstrating that the-22 bp from -51 to -30 have a major role in the cell-specific activity of the CIC-K1-promoter. These 22 bp consist of purine-rich sequence (GGGGAGGGG-GAGGGGAG), and gel-retardation analysis demonstrated the existence of a specific protein(s) binding to this element in IM cells. These results suggest that the novel purine-rich element may play a key role in the activity of the CIC-K1 gene promoter. Less