Regulation of AE2 mRNA expression in the cortical collecting duct by acid/base balance.
Regulation of AE2 mRNA expression in the cortical collecting duct by acid/base balance.
复制标题
通过酸/碱平衡调节皮质集合管中 AE2 mRNA 的表达。
DOI：
10.1152/ajprenal.1998.274.3.f596
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Náray-Fejes-Tóth,A
中科院分区：
文献类型：
--
作者：
Fejes-Tóth,G;Rusvai,E;Cleaveland,ES;Náray-Fejes-Tóth,A
AE 2 mRNA和蛋白质在几个肾单位节段中表达，其中之一是皮质集合管（CCD）。然而，AE 2在CCD的不同细胞类型中的分布以及AE 2在肾脏中的功能尚不清楚。本研究的目的是确定AE 2 mRNA在三种CCD细胞类型中的分布，并研究酸/碱平衡变化对其表达的影响。兔在NH 4Cl（酸）或NaHCO 3（碱）负荷18 h后，通过免疫解剖分离CCD细胞。通过RT-PCR测定AE 2 mRNA水平，并针对β-肌动蛋白水平进行标准化。我们发现CCD细胞表达高水平的AE 2 mRNA（约500拷贝/细胞）。碱负荷兔CCD细胞中AE 2 mRNA水平显著高于酸负荷兔CCD细胞，平均增加3.7 ± 1.07倍。还使用CCD细胞的原代培养物直接测试pH对AE 2 mRNA水平的影响。在酸性培养基中培养的CCD细胞表达AE 2 mRNA的水平显着低于正常或碱性培养基。用分离的主细胞、α-嵌入细胞和β-嵌入细胞（通过荧光激活细胞分选分离）进行的实验表明，AE 2 mRNA水平在三种集合管细胞亚型中相当，并且类似地受酸碱平衡变化的调节。基于这些结果，我们得出结论，适应细胞外H+浓度的变化是伴随着相反的AE 2 mRNA表达的变化。AE 2 mRNA不以细胞类型特异性方式表达，并且酸碱平衡的变化对每个CCD细胞亚型具有相似的影响，这一观察结果表明，AE 2可能具有管家功能，而不是β-嵌入细胞的顶端阴离子交换剂。
AE2 mRNA and protein is expressed in several nephron segments, one of which is the cortical collecting duct (CCD). However, the distribution of AE2 among the different cell types of the CCD and the function of AE2 in the kidney are not known. The purpose of this study was to determine the distribution of AE2 mRNA among the three CCD cell types and to examine the effects of changes in acid/base balance on its expression. Following NH4Cl (acid) or NaHCO3(base) loading of rabbits for ∼18 h, CCD cells were isolated by immunodissection. AE2 mRNA levels were determined by RT-PCR and were normalized for β-actin levels. We found that CCD cells express high levels of AE2 mRNA (∼500 copies/cell). AE2 mRNA levels were significantly higher in CCD cells originating from base-loaded than acid-loaded rabbits, with an average increase of 3.7 ± 1.07-fold. The effect of pH on AE2 mRNA levels was also tested directly using primary cultures of CCD cells. CCD cells incubated in acidic media expressed significantly lower levels of AE2 mRNA than those in normal or alkaline media. Experiments with isolated principal cells, α-intercalated cells, and β-intercalated cells (separated by fluorescence-activated cell sorting) demonstrated that AE2 mRNA levels are comparable in the three collecting duct cell subtypes and are similarly regulated by changes in acid/base balance. Based on these results, we conclude that adaptation to changes in extracellular H+concentration is accompanied by opposite changes in AE2 mRNA expression. The observations that AE2 mRNA is not expressed in a cell-type-specific manner and that changes in acid/base balance have similar effects on each CCD cell subtype suggest that AE2 might serve a housekeeping function rather than being the apical anion exchanger of β-intercalated cells.