Role of Claudin-2 in Inflammatory Diseases and Colon Cancer

Claudin-2 在炎症性疾病和结肠癌中的作用

• 批准号: 8970129
• 负责人: Amar B Singh
• 金额: $ 31.57万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-03 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8970129
• 关键词: Role; Claudin; Inflammatory; Diseases; Colon

DESCRIPTION (provided by applicant): Increased mucosal permeability is a key characteristic of the inflammatory bowel disease (IBD). The claudin family of proteins constitutes the tight junctions (TJs), which are the sole determinants of the paracellular permeability in an intact epithelium. Importantly, a common finding from the analysis of the IBD (Crohn's and Ulcerative Colitis) patient samples and related animal models is that claudin-2 expression is highly upregulated in the IBD. In the claudin family, Claudin-2 is unique as its expression correlates with the epithelial leakiness. However, it is also noteworthy that the colonic claudin-2 is expressed among the undifferentiated colonocytes at the crypt base, the proliferative zone. Furthermore, outcome from our preliminary studies and recently published studies from other labs suggest potential correlation of claudin-2 expression with the colonic epithelial cell proliferation and/or migration. It is further noteworthy that claudin-2 is a target of the Wnt/�-catenin signaling. However, role of claudin-2 in the pathogenesis of IBD is not known. To investigate, we generated Villin-claudin-2 transgenic (Cl-2Tg) mice that overexpress claudin-2 in the colon, a condition similar to the IBD. Our studies using these mice have provided novel outcomes: 1) Colonic epithelial permeability in Cl-2Tg mice is significantly increased compared to the WT littermates (p<0.05); 2) the colon and crypt lengths in Cl-2Tg mice are significantly increased compared to the wild type (WT) littermates (p<0.001 for both); and 3) Cl-2Tg mice are significantly protected from experimental-colitis [induced using dextran sodium sulfate (DSS, 4% w/v in drinking water)] compared to WT littermates (p<0.001). Our further data show sharp decreases in the DSS-induced expressions of proinflammatory cytokines including IL-1a, IL- 1�, TNF-a in Cl-2Tg mice compared to the WT littermates. On the other hand, gene expressions related with proliferation were upregulated in the DSS-treated Cl-2Tg mice compared to the DSS-treated WT littermates. Taken together, we postulate that claudin-2 plays an important role in the regulation of colonic homeostasis. We further hypothesize that immune adaptation/tolerance due to the constitutive increase in the mucosal permeability and/or modulations of the colonic epithelial cell proliferation/apoptosis or combination of both underlie the protection from DSS-colitis in Cl-2Tg mice. To test our hypothesis, we have proposed following specific aims: 1) To determine whether claudin-2 TG mice are protected against mucosal inflammation and disease; 2) To determine the role of claudin-2 in colitis-associated regeneration, repair and colitis-associated cancer; and 3) To determine the cellular and molecular mechanism/s underlying protection from colitis in claudin-2 TG mice. We anticipate that our studies will provide valuable and clinically relevant information that will have direct impact upon the understanding of the regulation of IBD pathogenesis and its progression to cancer, and will create potential new opportunities for therapeutic interventions.

描述（由申请人提供）：粘膜通透性增加是炎症性肠病（IBD）的关键特征。 密蛋白家族构成了紧密连接 (TJ)，它是完整上皮细胞旁细胞通透性的唯一决定因素。 重要的是，对 IBD（克罗恩病和溃疡性结肠炎）患者样本和相关动物模型的分析的一个共同发现是，claudin-2 表达在 IBD 中高度上调。 在 Claudin 家族中，Claudin-2 是独特的，因为它的表达与上皮渗漏相关。 然而，还值得注意的是，结肠claudin-2在隐窝基底（增殖区）的未分化结肠细胞中表达。 此外，我们的初步研究结果和其他实验室最近发表的研究结果表明，claudin-2 表达与结肠上皮细胞增殖和/或迁移存在潜在相关性。 进一步值得注意的是，claudin-2 是 Wnt/β-连环蛋白信号传导的靶标。 然而，claudin-2 在 IBD 发病机制中的作用尚不清楚。 为了进行研究，我们培育了 Villin-claudin-2 转基因 (Cl-2Tg) 小鼠，它们在结肠中过度表达claudin-2，这种情况与 IBD 类似。 我们使用这些小鼠的研究提供了新的结果：1）与 WT 同窝小鼠相比，Cl-2Tg 小鼠的结肠上皮通透性显着增加（p<0.05）； 2)与野生型(WT)同窝小鼠相比，Cl-2Tg小鼠的结肠和隐窝长度显着增加(两者p<0.001)； 3) 与 WT 同窝小鼠相比，Cl-2Tg 小鼠明显免受实验性结肠炎的影响（使用葡聚糖硫酸钠（DSS，饮用水中 4% w/v）诱导）（p<0.001）。 我们的进一步数据显示，与 WT 同窝小鼠相比，Cl-2Tg 小鼠中 DSS 诱导的促炎细胞因子（包括 IL-1a、IL-1α、TNF-a）的表达急剧下降。 另一方面，与 DSS 处理的 WT 同窝小鼠相比，DSS 处理的 Cl-2Tg 小鼠中与增殖相关的基因表达上调。 综上所述，我们假设claudin-2在结肠稳态的调节中发挥重要作用。 我们进一步假设，由于粘膜通透性的组成性增加和/或结肠上皮细胞增殖/凋亡的调节或两者的组合而导致的免疫适应/耐受是Cl-2Tg小鼠免受DSS结肠炎的保护的基础。 为了检验我们的假设，我们提出了以下具体目标：1）确定claudin-2 TG小鼠是否能够免受粘膜炎症和疾病的影响； 2) 确定claudin-2在结肠炎相关再生、修复和结肠炎相关癌症中的作用； 3) 确定claudin-2 TG 小鼠预防结肠炎的细胞和分子机制。 我们预计我们的研究将提供有价值的临床相关信息，这些信息将直接影响对 IBD 发病机制及其进展为癌症的调节的理解，并将为治疗干预创造潜在的新机会。