LPA stimulates intestinal DRA gene transcription via LPA2 receptor, PI3K/AKT, and c-Fos-dependent pathway.
LPA stimulates intestinal DRA gene transcription via LPA2 receptor, PI3K/AKT, and c-Fos-dependent pathway.
复制标题
DOI：
10.1152/ajpgi.00172.2011
复制
发表时间：
2012-03
期刊：
影响因子：
--
通讯作者：
Amika Singla;Anoop Kumar;S. Priyamvada;Maliha S Tahniyath;S. Saksena;R. Gill;W. Alrefai;P. Dudeja
中科院分区：
文献类型：
--
作者：
Amika Singla;Anoop Kumar;S. Priyamvada;Maliha S Tahniyath;S. Saksena;R. Gill;W. Alrefai;P. Dudeja
DRA(在腺瘤中下调)或SLC26A3是介导肠上皮细胞氯离子吸收的主要顶端阴离子交换器。DRA功能和表达的紊乱与腹泻有关，如先天性氯化物腹泻和炎症性肠病。先前的研究表明，DRA受到短期和转录机制的调节。在这方面，我们最近表明，溶血磷脂酸(LPA)是一种重要的生物活性磷脂，短期处理可通过增加人肠上皮细胞DRA表面水平来刺激Cl(-)/HCO(3)(-)(OH(-))交换活性。然而，LPA在基因转录水平上对DRA的长期影响尚未被研究。本研究旨在研究LPA对DRA功能和表达的影响，并阐明其转录调控机制。长期LPA处理可提高Caco-2细胞的Cl(-)/HCO(3)(-)交换活性。LPA处理(50-100μM)的Caco-2细胞可显著刺激DRA mRNA水平和DRA启动子活性(-1183/+114)。DRA启动子活性的增加涉及LPA2受体和磷脂酰肌醇3-激酶(PI3K)/AKT通路。从-1183/+114到-790/+114的渐进性缺失消除了LPA的刺激作用，表明-1183/-790启动子区含有LPA反应元件。利用EMSA和突变研究，我们的结果表明LPA以c-Fos依赖的方式诱导DRA启动子的活性。LPA还可增加Caco-2细胞c-Fos和c-Jun的蛋白表达。此外，c-Fos的过表达而不是c-Jun的过表达增强了DRA启动子的活性。这种对LPA反应的DRA转录增加表明LPA可能作为止泻剂，并可用于治疗与肠道炎症性或感染性疾病相关的腹泻。
DRA (downregulated in adenoma) or SLC26A3 is the major apical anion exchanger mediating Cl(-) absorption in intestinal epithelial cells. Disturbances in DRA function and expression have been implicated in diarrheal conditions such as congenital chloride diarrhea and inflammatory bowel diseases. Previous studies have shown that DRA is subject to regulation by short-term and transcriptional mechanisms. In this regard, we have recently shown that short-term treatment by lysophosphatidic acid (LPA), an important bioactive phospholipid, stimulates Cl(-)/HCO(3)(-)(OH(-)) exchange activity via an increase in DRA surface levels in human intestinal epithelial cells. However, the long-term effects of LPA on DRA at the level of gene transcription have not been examined. The present studies were aimed at investigating the effects of LPA on DRA function and expression as well as elucidating the mechanisms underlying its transcriptional regulation. Long-term LPA treatment increased the Cl(-)/HCO(3)(-) exchange activity in Caco-2 cells. LPA treatment (50-100 μM) of Caco-2 cells significantly stimulated DRA mRNA levels and DRA promoter activity (-1183/+114). This increase in DRA promoter activity involved the LPA2 receptor and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. Progressive deletions from -1183/+114 to -790/+114 abrogated the stimulatory effects of LPA, indicating that the -1183/-790 promoter region harbors LPA response elements. Utilizing EMSA and mutational studies, our results showed that LPA induced the DRA promoter activity in a c-Fos-dependent manner. LPA also increased the protein expression of c-Fos and c-Jun in Caco-2 cells. Furthermore, overexpression of c-Fos but not c-Jun enhanced the DRA promoter activity. This increase in DRA transcription in response to LPA indicates that LPA may act as an antidiarrheal agent and could be exploited for the treatment of diarrhea associated with inflammatory or infectious diseases of the gut.