Regulation of Intestinal PYY cell function

描述（由申请人提供）：肠内分泌细胞在营养消化和吸收中起关键作用，是正常生命所必需的。肠内分泌L细胞特别令人感兴趣，因为它具有感知肠腔内容物的能力，并且作为响应，分泌几种激素。其中两种激素处于糖尿病和肥胖研究的最前沿：1）胰岛素刺激胰高血糖素样肽1（GLP-1）; 2）饱腹感诱导肽酪氨酸（PYY）。为了研究L细胞，申请人的实验室开发了转基因小鼠模型，其中PYY启动子驱动增强型绿色荧光蛋白（GFP）的表达。使用PYY- GFP模型沿着共聚焦激光扫描显微镜（LSCM），申请人和他的团队已经表征了L细胞中类似轴突的长（超过50 μ m）基底细胞质突起的存在.申请人的长期目标是理解肠内分泌细胞，特别是L细胞如何与肠神经元交换分子信息以诱导饱腹感和调节食欲。该提案的目的是通过评估其在PYY分泌中的作用以及表征调节其生长和维持的因素来确定L细胞基底过程在L细胞功能中的重要性。中心假设是L细胞基底突由来自肠神经胶质的特定信号滋养，并起假轴突的作用。该假设是基于申请人开发的初步数据制定的，这些数据表明L细胞与肠神经系统的元件具有密切关系。其基本原理是，通过定义的功能和调节的基础过程，可以开发新的方法来调节激素分泌的L细胞。中心假设将在两个特定的目标进行测试：目标1是确定神经营养因子对L细胞中轴突样延伸的影响。申请人将在培养的原代L细胞和含有L细胞的肠类器官模型中检查轴突突起伸长。目的二是研究L细胞基底突中神经丝的特征及其在PYY分泌中的作用。申请人将使用RNAi技术在体外和体内研究L细胞中发现的神经丝。因为PYY是主要的饱腹感信号，所以预期L细胞和肠神经元之间的物理连接对食欲调节具有重要影响。拟议的项目将为申请人提供必要的培训，使其成为胃肠道内分泌学领域的独立研究者。

DESCRIPTION (provided by applicant): Enteroendocrine cells play a key role in nutrient digestion and absorption, and are essential for normal life. The enteroendocrine L cell is of particular interest because it has the capacity to sense contents of the gut lumen and, in response, secretes several hormones. Two of those hormones are at the forefront of diabetes and obe- sity research: 1) the insulin-stimulating glucagon-like peptide 1 (GLP-1); and, 2) the satiety-inducing peptide tyrosine tyrosine (PYY). To study L cells, the applicant's laboratory has developed a transgenic mouse model in which the PYY promoter drives the expression of enhanced green fluorescent protein (GFP). Using the PYY- GFP model along with confocal laser scanning microscopy (LSCM), the applicant and his team have characterized the existence in L cells of a long (more than 50 5m) basal cytoplasmic process that resembles an axon. The long-term goal of the applicant is to understand how enteroendocrine cells, in particular the L cell, ex- change molecular information with enteric neurons to induce satiety and regulate appetite. The objective of this proposal is to determine the importance of the L cell basal process in the function of L cells, by assessing its role in PYY secretion and by characterizing the factors that regulate its growth and maintenance. The central hypothesis is that the L cell basal process is nurtured by specific signals derived from enteric glia, and functions as a pseudo-axon. The hypothesis has been formulated based on preliminary data developed by the applicant that show that L cells have an intimate relationship with elements of the enteric nervous system. The rationale is that by defining the function and regulation of basal processes new approaches can be developed to modulate hormone secretion from L cells. The central hypothesis will be tested in two specific aims: Aim 1 is to determine the effects of neurotrophic factors on the axon-like extension in L cells. The applicant will examine axonal process elongation in cultured primary L cells and in an intestinal organoid model that contains L cells. Aim 2 is to characterize the neurofilaments in L cell basal processes and define their role in PYY secretion. The applicant will use RNAi techniques to study in vitro and in vivo the neurofilaments found in L cells. Because PYY is a major satiety signal, the physical connection between the L cell and enteric neurons is ex- pected to carry important consequences for the regulation of appetite. The proposed project will provide the applicant with the required training to become an independent investigator in the field of gastrointestinal endocrinology.