Study of Reg Receptor-Ligand Biology in the GI Mucosa

描述(申请人提供)：炎症性肠病是一种 以持续的粘膜损伤和再生为特征的疾病。我们应用了信使核糖核酸 基因芯片杂交和高通量文库的转录谱分析 用于在胃肠道中识别新的或未知基因的测序 潜在地调节保护性或再生程序的粘膜。我们的 结果发现，REG基因家族的成员是最高级别的 诱导IBD黏膜中的mRNAs，提示它们可能发挥重要作用 在粘膜修复中。而这个基因家族的生物学功能仍然存在 人们对此知之甚少，最近的研究表明，REG蛋白可能作为 组织有丝分裂原。我们鉴定并纯化了一种新的REG细胞表面 与REG I-α结合的受体(REG-R)。重组REG的治疗作用 I-α诱导ERK蛋白激酶快速激活并呈剂量依赖关系 路径。REG-R受体是一种跨膜蛋白，它只包含一个 胞质结构域小，缺乏受体所需的结构特征 耦合到下游信号通路。因此，我们还确定了 与REG-R共同纯化的第二种蛋白质。我们的三部分假设是：(1) REG基因家族的所有成员都结合并激活这个细胞表面 受体，(2)活性受体复合体包含REG-R和附加的 具有信号所需的细胞质决定因素的亚基 转导；(3)单个REG蛋白及其同源受体 络合物构成了一种新的受体-配体系统，对细胞周期具有独特的重要性 胃肠粘膜的维护和修复。我们建议使用新的 开发的工具可以直接在三个具体目标上检验这一假设：(1) 确定单个REG基因之间的能力是否存在差异 结合并激活受体介导的信号转导。描述一下 表达REG-R的粘膜种群与正常胃粘膜的空间关系 REG基因产物在正常和病变胃肠黏膜中的定位； (2)鉴定REG-R复合体的其他成分，并阐明 配体介导的受体信号的结构要求；以及(3) 研究REG-R-配体系统在体外和体内作为一种 建立小鼠REG-R功能丧失模型的前奏。这包括 检测该受体配体的功能作用的实验 体外和体内与异位或异位相关的病理模型 REG蛋白表达增加。这些研究将提供重要的新的 对调节粘膜再生程序的因素的洞察，并可能导致 治疗影响胃肠粘膜的疾病的新方法，如 炎症性肠病。

DESCRIPTION (provided by applicant): Inflammatory bowel disease (IBD) is a disease marked by ongoing mucosal injury and regeneration. We have applied mRNA transcript profiling by GeneChip hybridization and high-throughput library sequencing to identify novel or unsuspected genes in the gastrointestinal mucosa that potentially mediate protective or regenerative programs. Our results have identified members of the REG gene family as among the most highly induced mRNAs in IBD mucosa, suggesting that they may serve an important role in mucosal repair. While the biological function for this gene family remains poorly understood, recent work has suggested that REG proteins may serve as tissue mitogens. We have identified and purified a novel REG cell surface receptor (REG-R) that binds to Reg I-alpha. Treatment with recombinant Reg I-alpha resulted in rapid and dose-dependent activation of the ERK MAP kinase pathway. The REG-R receptor is a transmembrane protein that contains only a small cytoplasmic domain and lacks structural features required for receptor coupling to downstream signaling pathways. Accordingly, we have also identified a second protein that co-purifies with REG-R. Our three part hypothesis is: (1) all members of the REG gene family bind and activate this cell surface receptor, (2) the active receptor complex contains the REG-R and an additional subunit possessing the cytoplasmic determinants required for signal transduction, and (3) individual REG proteins and their cognate receptor complex constitute a new receptor-ligand system with unique importance to the maintenance and repair of the gastrointestinal mucosa. We propose to use newly developed tools to directly test this hypothesis in three specific aims: (1) determine if differences exist between individual REG genes in their ability to bind and activate receptor-mediated signal transduction. Characterize the spatial relationship between mucosal populations expressing the REG-R and the location of REG gene products in normal and diseased gastrointestinal mucosa; (2) Characterize additional components of the REG-R complex and elucidate the structural requirements of ligand-mediated receptor signaling; and (3) Investigate the role for the REG-R-ligand system in vitro and in vivo as a prelude to developing a murine REG-R loss-of-function model. This includes experiments to examine the functional role served by this receptor ligand system in vitro and under in vivo pathologic models associated with ectopic or increased expression of REG proteins. These studies will provide important new insights into factors that regulate mucosal regenerative programs and may lead to new ways to treat diseases affecting the gastrointestinal mucosa like inflammatory bowel disease.