Rieder Carmen V, Fliegel Larry
Department of Biochemistry, University of Alberta, Canadian Institute of Health Research Membrane Protein Group, Edmonton, Alberta, Canada T6G 2H7.
Am J Physiol Heart Circ Physiol. 2002 Jul;283(1):H273-83. doi: 10.1152/ajpheart.00042.2002.
We examined the hypothesis that Na(+)/H(+) exchanger expression is regulated during fetal and neonatal development and differentiation. To examine transcriptional regulation of the NHE1 isoform of the Na(+)/H(+) exchanger, transgenic mice were created that contained the mouse NHE1 promoter driving expression of green fluorescent protein. The level of NHE1 transcription varied between tissues and with the stage of embryonic development. The highest expression was in the heart and liver of 12- to 15-day-old mice, and this declined with age. To examine Na(+)/H(+) exchanger protein levels, we immunoblotted mouse tissues from 18-day-old embryos, neonates, and adults. Protein levels increased after embryonic day 18 and peaked at 14 days of age in the heart, lung, liver, kidney, and brain. The greatest rise in NHE1 protein expression occurred in the heart, whereas the smallest increase was in the brain. The results suggest that Na(+)/H(+) exchanger transcription and protein levels are controlled in a tissue-specific and time-dependent manner during development.
在胎儿期和新生儿期的发育与分化过程中，钠氢交换体（Na(+)/H(+) exchanger）的表达受到调控。为了研究钠氢交换体NHE1亚型的转录调控，构建了转基因小鼠，其包含驱动绿色荧光蛋白表达的小鼠NHE1启动子。NHE1的转录水平在不同组织间以及胚胎发育阶段有所不同。最高表达出现在12至15日龄小鼠的心脏和肝脏中，且随年龄增长而下降。为检测钠氢交换体蛋白水平，我们对18日龄胚胎、新生儿及成年小鼠的组织进行了免疫印迹分析。蛋白水平在胚胎第18天之后升高，并在心脏、肺、肝脏、肾脏和大脑中于14日龄时达到峰值。NHE1蛋白表达升高幅度最大的是心脏，而最小的是大脑。结果表明，在发育过程中，钠氢交换体的转录和蛋白水平以组织特异性和时间依赖性方式受到控制。
