Intestinal distribution of human Na+/H+ exchanger isoforms NHE-1, NHE-2, and NHE-3 mRNA
Intestinal distribution of human Na+/H+ exchanger isoforms NHE-1, NHE-2, and NHE-3 mRNA
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DOI：
10.1152/ajpgi.1996.271.3.g483
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发表时间：
1996-09-01
影响因子：
4.5
通讯作者：
Ramaswamy, K
中科院分区：
文献类型：
--
作者：
Dudeja, PK;Rao, DD;Ramaswamy, K
人类小肠和结肠中Na+/H+交换器(NHE)亚型的同源性及其在载体Na+吸收中的作用尚不清楚。本研究旨在研究NHE-1、NHE-2和NHE-3mRNA在人肠道中的区域和垂直轴分布。用核糖核酸酶保护试验定量检测这些异构体在人体肠道不同区域的mRNA水平。用原位杂交技术对NHE-2和NHE-3mRNA在结肠中的表达进行定位。NHE-1异构体信息在整个人类肠道中均匀存在。相比之下，人类NHE-2和NHE-3亚型的mRNA水平显示出显著的地区差异。NHE-3的表达由高到低依次为回肠和GT、空肠和GT、近端结肠=远端结肠。NHE-2在远端结肠中的表达水平显着高于近端结肠，但在小肠中分布均匀。此外，NHE-2mRNA存在于结肠隐窝表面上皮细胞和隐窝区域的细胞中，提示NHE-2信息存在于整个结肠隐窝的垂直轴上。相反，NHE-3mRNA定位于近端结肠的表面结肠细胞。根据NHE-2和NHE-3mRNA的组织特异性定位，可以推测NHE-2和NHE-3亚型在人体肠道Na+吸收中的相对贡献可能是区域特异性的，这些可能的顶端亚型可能受到不同的调控。
The identity of Na+/H+ exchanger (NHE) isoforms in the human small intestine and colon and their role in vectorial Na+ absorption are not known. The present studies were undertaken to examine the regional and vertical axis distribution of NHE-1, NHE-2, and NHE-3 mRNA in the human intestine. Ribonuclease protection assays were used to quantitate the levels of mRNA of these isoforms in various regions of the human intestine. In situ hybridization technique was used to localize NHE-2 and NHE-3 mRNA in the colon. The NHE-1 isoform message was present uniformly throughout the length of the human intestine. In contrast, mRNA levels for human NHE-2 and NHE-3 isoforms demonstrated significant regional differences. The NHE-3 abundance was found in decreasing order: ileum > jejunum > proximal colon = distal colon. The NHE-2 message level in the distal colon was significantly higher than in the proximal colon but was evenly distributed in the small intestine. In addition, NHE-2 mRNA was present in surface epithelial cells as well as in cells of the crypt region, suggesting the presence of NHE-2 message throughout the vertical axis of the colonic crypts. In contrast, NHE-3 mRNA was localized to surface colonocytes in the proximal colon. On the basis of this tissue-specific localization of NHE-2 and NHE-3 mRNA, it can be speculated that the relative contribution of NHE-2 and NHE-3 isoforms in Na+ absorption in the human intestine may be region specific, and these putative apical isoforms may be differentially regulated.