Elucidating the role of Myosin 5b in intestinal inflammation

肠上皮通过维持屏障并对腔内抗原和细菌信号作出适当反应，在体内平衡和健康中发挥重要作用。上皮通过被称为微绒毛的数千个富含肌动蛋白的突起来完成这些功能。微绒毛含有向上皮细胞传递信息的蛋白质。微绒毛顶端的一种重要蛋白质是肠碱性磷酸酶，这种酶可以解毒促炎细菌和宿主衍生的化合物，并将上皮损伤降到最低。微绒毛通过称为微绒毛间粘附复合物（IMAC）的连接蛋白保持在适当的高度、距离和密度。我们的初步数据表明，IMAC化合物和肠碱性磷酸酶通过分子马达肌球蛋白5b传递到上皮细胞的顶端成员。在我们的动物模型中，功能性肌球蛋白5b的缺失以及随后imac和肠道碱性磷酸酶的错误定位改变了微绒毛的结构和功能，我们假设这为上皮功能障碍奠定了基础。最近有研究表明，炎症性肠病（IBD）患者Myosin 5b基因表达降低，上皮细胞上的微绒毛缩短、紊乱。我们的初步数据表明，在IBD患者的结肠活检和TNBS结肠炎小鼠模型中，Myosin 5b蛋白减少。我们假设炎症降低Myosin 5b基因表达和蛋白水平，从而导致IMAC和肠道碱性磷酸酶蛋白的错误定位，并使炎症循环持续下去。为了解决这个问题，我们建议使用急性（DSS）和慢性（t细胞转移）动物结肠炎模型（Aim 1）来确定Myosin 5b在肠道炎症中的作用，并确定促炎刺激下调Myosin 5b的机制，以及Myosin 5b的降低如何为小鼠和人类肠道类器官的进一步损伤奠定基础（Aim 2）。这项工作有可能确定参与肠道炎症的关键途径；可以用来开发下一代疗法的靶点。这项研究可能会导致改善患者健康结果和生活质量的治疗方法。

The intestinal epithelium plays an essential role in homeostasis and health by maintaining a barrier and responding appropriately to luminal antigens and bacterial signals. The epithelium accomplishes these functions via thousands of actin-rich protrusions known as microvilli. Microvilli harbor proteins which relay information to the epithelial cell. One important protein at the tips of the microvilli is intestinal alkaline phosphatase -an enzyme that detoxify pro-inflammatory bacterial and host derived compounds and minimizes epithelial insults. Microvilli are maintained at the proper height, distance and density by linker proteins known as the intermicrovillar adhesion complex (IMAC). Our preliminary data indicates that IMAC compounds and intestinal alkaline phosphatase are delivered to the apical member of epithelial cells by the molecular motor Myosin 5b. Loss of functional Myosin 5b and subsequent mislocalization of IMACs and intestinal alkaline phosphatase alters the structure and function of microvilli in our animal model, and we postulate that this sets the stage for epithelial dysfunction. Recently it has been demonstrated that patients with Inflammatory Bowel Disease (IBD) have decreased gene expression of Myosin 5b and have shortened, disordered microvilli on their epithelial cells. Our preliminary data indicates that Myosin 5b protein is decreased in colonic biopsies of IBD patients and in a TNBS mouse model of colitis. We hypothesize that inflammation decreases Myosin 5b gene expression and protein levels, which leads to the mislocalization of IMAC and intestinal alkaline phosphatase protein and perpetuates a cycle of inflammation. To address this question, we propose to define the role of Myosin 5b in intestinal inflammation using acute (DSS) and chronic (T-cell transfer) animal colitis models (Aim 1) and define the mechanisms by which pro-inflammatory stimuli downregulate Myosin 5b and how decreased Myosin 5b sets the stage for further insults using mouse and human intestinal organoids (Aim 2). This work has the potential to identify key pathways involved in intestinal inflammation; targets which could be used to develop next generation therapeutics. This research may lead to treatments which enhance patient health outcomes and quality of life.