Intestinal 5-HT Transporter: A novel therapeutic target for GI disorders

肠道 5-HT 转运蛋白：胃肠道疾病的新型治疗靶点

• 批准号: 8629924
• 负责人: Ravinder K Gill
• 金额: $ 27.41万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8629924
• 关键词: 1-Phosphatidylinositol 3-Kinase; Acute; Attenuated; Cell Culture Techniques; Cell membrane; Colitis; Communicable Diseases; Crohn' s disease; Data; Diarrhea; Disease; Down-Regulation; Enteral; Event; Exhibits; Experimental Models; Functional disorder; Gastrointestinal Diseases; Gene Expression; Health; Human; Ileitis; In Vitro; Infection; Inflammation; Inflammation Mediators; Inflammatory; Inflammatory Bowel Diseases; Inflammatory Response; Inflammatory disease of the intestine; Intervention; Intestines; Investigation; Knock-out; Knockout Mice; Laboratories; Liquid substance; Membrane Protein Traffic; Messenger RNA; Modeling; Molecular; Mus; Pain; Pathway interactions; Patients; Phenotype; Phosphorylation; Protein Kinase; Protein Tyrosine Phosphatase; Receptor Signaling; Regulation; Reporter; Reporting; Repression; Research Design; Role; Serotonin; Signal Transduction; Signal Transduction Pathway; Small Intestines; Surface; TNF gene; Testing; Time; Tissues; Transforming Growth Factors; Transgenic Mice; Tumor Necrosis Factor-Beta; Ulcerative Colitis; Up-Regulation; Water Movements; Wild Type Mouse; cell motility; ileum; improved; in vitro Model; in vivo; in vivo Model; insight; mRNA Expression; mouse model; new therapeutic target; novel; novel therapeutic intervention; overexpression; promoter; protein expression; repaired; response; serotonin transporter; trafficking

DESCRIPTION (provided by applicant): Gastrointestinal disorders such as inflammatory bowel diseases (IBD) and diarrhea remain a major health burden, warranting investigations aimed at better treatment options. Increasing evidence implicates a decrease in intestinal 5-HT transporter (SERT) and the consequent high luminal 5-HT levels in the pathophysiology of diarrheal and inflammatory disorders of the intestine both in humans and experimental models of inflammation or infection. As an important example, SERT KO mice exhibit diarrheal phenotype, abnormal motility and exacerbation of inflammatory responses. Therefore, it is critical to understand the regulation of SERT, a novel target for the treatment of GI disorders. However, very little is known regarding mechanisms underlying dysregulation of intestinal SERT under pathophysiological conditions. Previous studies from our laboratory and others have demonstrated that intestinal SERT activity is subject to regulation by protein kinases, protein tyrosine phosphatases and alterations at the level of gene expression. SERT has been previously shown to be inhibited by the pro-inflammatory mediators, LPS and TNF via distinct mechanisms. For example, LPS decreased SERT levels at the plasma membrane, whereas, TNF reduced SERT mRNA expression, albeit the detailed mechanisms underlying these effects are not known. Whether SERT upregulation can prove effective in counteracting SERT inhibition and alleviation of inflammatory and diarrheal phenotype is also not known. In this regard, our preliminary studies showed that SERT function is stimulated by TGF-β1 by post- translational mechanisms as well as via alterations at the level of gene expression in IECs. Thus, to establish the role of intestinal SERT as a novel target of GI disorders, proposed studies will test the hypothesis that SERT function and/or expression is increased by distinct signaling, trafficking and molecular mechanisms, which can counteract the inhibition of SERT in pathophysiological states to reverse diarrhea or inflammation. Studies proposed in Specific Aim 1 will elucidate the signaling and membrane trafficking events modulating SERT in response to TGF-β1 or LPS. Specific Aim 2 will elucidate the molecular mechanisms modulating SERT gene expression in response to long-term TNF or TGF- β1 and investigate the cross-talk of their signaling/molecular pathways. Specific Aim 3 will critically examine whether luminal fluid accumulation (hallmark of diarrhea) caused by TNF or inflammation in SAMP/yitc mice (model of ileitis resembling Crohn's disease) is reversed by TGF-β1. Furthermore, mechanisms modulating SERT in response to TNF and their reversal by TGF-β1 will be examined in the native intestine utilizing wild type, SERT knock out and DNIIR mice, (lacking TGF- β receptor signaling). Overall, these studies are designed to provide valuable insights into the mechanisms upregulating intestinal SERT in pathophysiological conditions, where TGF-β1 signaling is defective and/or SERT expression is downregulated. Thus, these studies should establish the role of SERT as a novel therapeutic target for intervention in IBD and associated diarrhea.

描述（由申请人提供）：炎症性肠病（IBD）和腹泻等胃肠道疾病仍然是主要的健康负担，需要进行旨在更好的治疗选择的研究。越来越多的证据表明，肠道 5-HT 转运蛋白 (SERT) 的减少以及随之而来的高管腔 5-HT 水平与人类和炎症或感染实验模型的腹泻和肠道炎症性疾病的病理生理学有关。作为一个重要的例子，SERT KO 小鼠表现出腹泻表型、运动异常和炎症反应加剧。因此，了解 SERT 的调节至关重要，SERT 是治疗胃肠道疾病的新靶点。然而，对于病理生理条件下肠道 SERT 失调的机制知之甚少。我们实验室和其他实验室之前的研究表明，肠道 SERT 活性受到蛋白激酶、蛋白酪氨酸磷酸酶和基因表达水平改变的调节。先前已证明 SERT 可通过不同的机制受到促炎介质 LPS 和 TNF 的抑制。例如，LPS 降低了质膜上的 SERT 水平，而 TNF 则降低了 SERT mRNA 的表达，尽管这些作用背后的详细机制尚不清楚。 SERT 上调是否可以有效对抗 SERT 抑制以及减轻炎症和腹泻表型也尚不清楚。在这方面，我们的初步研究表明，SERT 功能是通过翻译后机制以及 IEC 基因表达水平的改变而被 TGF-β1 刺激的。因此，为了确定肠道 SERT 作为胃肠道疾病新靶点的作用，拟议的研究将检验以下假设：SERT 功能和/或表达通过不同的信号传导、运输和分子机制而增加，这可以抵消病理生理状态下 SERT 的抑制，从而逆转腹泻或炎症。具体目标 1 中提出的研究将阐明响应 TGF-β1 或 LPS 调节 SERT 的信号传导和膜运输事件。具体目标 2 将阐明调节 SERT 基因表达以响应长期 TNF 或 TGF-β1 的分子机制，并研究其信号传导/分子途径的串扰。具体目标 3 将严格检查 SAMP/yitc 小鼠（类似于克罗恩病的回肠炎模型）中由 TNF 或炎症引起的管腔积液（腹泻的标志）是否可以被 TGF-β1 逆转。此外，将利用野生型、SERT 敲除小鼠和 DNIIR 小鼠（缺乏 TGF-β 受体信号传导）在天然肠道中检查响应 TNF 调节 SERT 及其通过 TGF-β1 逆转的机制。总体而言，这些研究旨在为病理生理条件下上调肠道 SERT 的机制提供有价值的见解，其中 TGF-β1 信号传导存在缺陷和/或 SERT 表达下调。因此，这些研究应该确立 SERT 作为干预 IBD 和相关腹泻的新治疗靶点的作用。