Intestinal NHE8 is highly expressed in goblet cells and its expression is subject to TNF-α regulation.
Intestinal NHE8 is highly expressed in goblet cells and its expression is subject to TNF-α regulation.
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肠道NHE8在杯状细胞中高表达，其表达受TNF-α调节。
DOI：
10.1152/ajpgi.00367.2015
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Ghishan,FayezK
中科院分区：
文献类型：
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作者：
Xu,Hua;Li,Qingtian;Zhao,Yang;Li,Jing;Ghishan,FayezK
虽然肠道在消化和吸收中起着重要作用，但上皮细胞的粘液在粘膜保护中起着关键作用。杯状细胞分散在隐窝和肠上皮细胞中，它们分泌粘液的重要成分粘蛋白。我们已经报道了钠/氢交换器（NHE）8是粘膜保护中的新型参与者，因为NHE 8功能的丧失导致粘蛋白产生减少和细菌粘附增加。虽然NHE 8已被证明在肠上皮细胞中表达，并且其表达在肠道炎症期间减少，但对NHE 8在杯状细胞中的作用一无所知。本研究旨在明确杯状细胞中NHE 8的表达以及TNF-α在NHE 8调节中的作用。以HT 29-MTX细胞为体外培养模型，我们在杯状细胞中检测到丰富的NHE 8 mRNA。免疫组织化学染色定位NHE 8蛋白质的质膜和细胞内的隔室中的杯状细胞。此外，杯状细胞中的NHE 8表达受促炎细胞因子TNF-α调节。在TNF-α存在下，HT 29-MTX细胞中NHE 8在mRNA和蛋白水平上的表达均显著降低。转录抑制剂放线菌素D可阻断NHE 8 mRNA表达的抑制作用。启动子报告基因分析表明TNF-α确实降低了NHE 8启动子活性。从机制上讲，TNF-α减少了Sp3蛋白与人NHE 8基础启动子区的结合。因此，NHE 8在杯状细胞中表达，并且炎性细胞因子TNF-α通过转录机制下调NHE 8表达。
While the intestine plays an important role in digestion and absorption, the mucus lining the epithelium represents a pivotal function in mucosal protection. Goblet cells are scattered in both the crypts and among enterocytes, and they secrete an important component of mucus, mucin. We have reported that sodium/hydrogen exchanger (NHE) 8 is a novel player in mucosal protection, since loss of NHE8 function resulted in reduced mucin production and increased bacterial adhesion. While NHE8 has been shown to be expressed in enterocytes and its expression is reduced during intestinal inflammation, nothing is known about the role of NHE8 in goblet cells. This current study is designed to define the expression of NHE8 and the role of TNF-α in the regulation of NHE8 in goblet cells. Using HT29-MTX cells as an in vitro model, we detected abundant NHE8 mRNA in goblet cells. Immunohistochemical staining localized NHE8 protein on the plasma membrane and in the intracellular compartments in goblet cells. Furthermore, NHE8 expression in goblet cells is regulated by the proinflammatory cytokine TNF-α. The expression of NHE8 in HT29-MTX cells was significantly reduced at both mRNA and protein levels in the presence of TNF-α. This inhibition of NHE8 mRNA expression could be blocked by the transcriptional inhibitor actinomycin D. Promoter reporter assay showed that NHE8 promoter activity was indeed reduced by TNF-α. Mechanistically, TNF-α reduced Sp3 protein binding to the human NHE8 basal promoter region. Therefore, NHE8 is expressed in goblet cells, and the inflammatory cytokine TNF-α downregulates NHE8 expression by a transcriptional mechanism.