Vallet V, Bens M, Antoine B, Levrat F, Miquerol L, Kahn A, Vandewalle A
Institut National de La Santé et de la Recherche Médicale (INSERM) U129, Institut Cochin de Génétique Moléculaire, Université René Descartes, Paris, France.
Exp Cell Res. 1995 Feb;216(2):363-70. doi: 10.1006/excr.1995.1046.
Renal expression of the aldolase B isoenzyme and transcription factors previously shown to regulate the aldolase B gene promoter in the liver were analyzed in whole kidney, microdissected tubules, and the two PKSV-PCT and PKSV-PR proximal tubule cell lines derived from transgenic mice. Aldolase B gene expression appeared restricted to the proximal tubule, the site where HNF1 alpha, HNF1 beta, C/EBP alpha, and DBP transcripts were also abundant. Compared to the liver, another organ synthesizing aldolase B, proximal tubules from the kidney were characterized by the absence of HNF3 and the presence of higher ratio of HNF1 beta/HNF1 alpha transcripts. The same features were conserved in both PKSV-PCT and PKSV-PR proximal tubule cell lines. Transactivation experiments in PKSV-PCT cultured cells showed that HNF1 alpha, C/EBP alpha, and DBP behave as transactivators of the 190-bp aldolase B gene promoter, and that HNF1 beta had a low transactivating efficiency. HNF1 beta, as well as HNF3, antagonized the HNF1 alpha-dependent transactivation of the aldolase B promoter. The fact that both HNF1 beta and HNF3 factors play similar negative roles by competitively binding close to or on the HNF1 site could suggest that, in proximal tubule renal cells, HNF1 beta has the same attenuator effect on the aldolase B gene promoter as HNF3 in hepatocytes. Thus, these results indicate that such models of established renal tubule cell lines, which have conserved the same features of parental cells, represent valuable tools for studies of the regulation of genes expressed in proximal tubules of the kidney.
在全肾、显微切割的肾小管以及源自转基因小鼠的两种PKSV - PCT和PKSV - PR近端小管细胞系中,分析了醛缩酶B同工酶的肾表达以及先前已证明可调节肝脏中醛缩酶B基因启动子的转录因子。醛缩酶B基因表达似乎局限于近端小管,HNF1α、HNF1β、C/EBPα和DBP转录本在该部位也很丰富。与另一个合成醛缩酶B的器官肝脏相比,肾近端小管的特征是不存在HNF3,且HNF1β/HNF1α转录本的比例更高。这两个特征在PKSV - PCT和PKSV - PR近端小管细胞系中均得以保留。在PKSV - PCT培养细胞中进行的反式激活实验表明,HNF1α、C/EBPα和DBP可作为190 bp醛缩酶B基因启动子的反式激活因子,而HNF1β的反式激活效率较低。HNF1β以及HNF3可拮抗醛缩酶B启动子的HNF1α依赖性反式激活。HNF1β和HNF3因子通过竞争性结合靠近或位于HNF1位点上而发挥相似的负性作用,这一事实可能表明,在近端小管肾细胞中,HNF1β对醛缩酶B基因启动子的衰减作用与肝细胞中的HNF3相同。因此,这些结果表明,这种已建立的肾小管细胞系模型保留了亲代细胞的相同特征,是研究肾近端小管中表达基因调控的有价值工具。