Molecular Mechanisms Regulating Intestinal Homeostasis

描述(申请人提供)：肠粘膜通过时空调节增殖、分化、迁移和细胞死亡来维持其完整性。协调这些事件的分子机制，特别是在损伤修复的背景下，还不是很清楚。此外，目前尚不清楚 这些过程的扰动如何影响细胞连接的形成和屏障功能。Kruppel-like factor5(KLF5)是转录因子家族中的一员。 调节不同的细胞过程，包括发育、增殖和分化。 KLF5在肠上皮细胞的增殖成分中高表达，并在体外和体内被证明能促进肠上皮细胞的增殖。最近来自肠道特异缺失KLF5的小鼠的DAT表明，KLF5是维持肠道隐窝结构和上皮屏障完整性所必需的。此外，最近的研究表明，KLF5对葡聚糖硫酸钠(DSS)诱导的小鼠结肠炎模型的粘膜愈合是必需的。基于这些结果，我们假设KLF5控制着隐窝-腔轴上皮细胞的更新和成熟，并且是肠上皮完整性所必需的。为了验证这一假说，已开发了以下目标：(I)确定KLF5在调节肠腺-腔轴上皮细胞的增殖、迁移和成熟中的作用。遗传小鼠模型和细胞培养系统将用于KLF5的异位表达或抑制，以探讨KLF5在调节肠上皮细胞动态平衡过程中的作用。(Ii)确定KLF5维持肠道功能的需要量 上皮屏障功能。KLF5的表达对肠道通透性和顶端连接复合体形成的影响将被确定。(3)研究KLF5在肠上皮损伤修复中的作用。这些实验将测试增加KLF5水平是否可以改善DSS诱导的结肠炎的结局和上皮愈合。将测试几种提高KLF5在小鼠结肠中表达的方法，包括腺病毒传递、纳米颗粒传递和转基因表达。还将使用具有可诱导的肠道特异性KLF5缺失的小鼠进行相互研究，以测试KLF5是否是修复肠道损伤所必需的。这些研究的长期目标是阐明在组织更新和损伤修复的情况下调节肠上皮完整性的分子机制。建议的研究将有助于更好地了解协调增殖、迁移和分化过程的因素，以维持肠道结构和屏障功能。特别是，这些研究将探索KLF5在上皮成熟、迁移和细胞连接形成过程中的新作用，以及KLF5作为炎症性肠病等疾病的治疗靶点的可能性。

DESCRIPTION (provided by applicant): The intestinal mucosa maintains its integrity through spatiotemporal regulation of proliferation, differentiation, migration, and cell death along the crypt-luminal axis of the intestine. The molecular mechanisms that coordinate these events, particularly in the context of injury repair, are not well understood. Furthermore, it is not known how perturbations of these processes impact cell junction formation and barrier function. Kruppel- like factor 5 (KLF5) is a member of a family of transcription factors that function in the regulation of diverse cellular processes including development, proliferation, and differentiation. KLF5 is highly expressed in the proliferative component of the intestinal epithelium, and has been shown to promote proliferation of intestinal epithelial cells in vitro and in vivo. Recent dat from mice with intestine-specific deletion of Klf5 indicate that KLF5 is required for maintenance of intestinal crypt architecture and epithelial barrier integrity. In addition, it was shown recenty that KLF5 is necessary for mucosal healing in the dextran sulfate sodium (DSS) mouse model of colitis. Based on these results, we hypothesize that KLF5 controls renewal and maturation of epithelial cells along the crypt-luminal axis and is required for intestinal epithelial integrity. he following aims have been developed to test this hypothesis: (I) Define the role of KLF5 in regulating proliferation, migration, and maturation of epithelial cells along the crypt-luminal axi of the intestine. Genetic mouse models and cell culture systems will be used for ectopic expression or inhibition of KLF5 to explore the role of KLF5 in regulating processes involved in intestinal epithelial homeostasis. (II) Determine the requirement of KLF5 in maintaining intestinal epithelial barrier function. The effects of KLF5 expression on intestinal permeability and the formation of apical junctional complexes will be determined. (III) Examine the role of KLF5 in intestinal epithelial wound repair. These experiments will test whether increased levels of KLF5 can improve outcome and epithelial healing in DSS-induced colitis. Several methods to increase KLF5 expression in the mouse colon will be tested, including adenoviral delivery, nanoparticle delivery and transgenic expression. Reciprocal studies using mice with inducible intestine-specific deletion of Klf5 will also be conducted to test whether KLF5 is necessary for repair of intestinal injury. The long-term goal of these studies is to elucidate the molecular mechanisms that regulate intestinal epithelial integrity, both in situations of tissue renewal and injury repar. The proposed studies will contribute to a better understanding of factors that coordinate the processes of proliferation, migration, and differentiation to maintain intestinal architecture and barrier function. In particular, these studies will explore novel roles for KLF5 in the processes o epithelial maturation, migration, and cell junction formation, and the possibility for KLF5 as a therapeutic target in disease conditions such as inflammatory bowel disease.