The Role of Clec16a in the Pancreatic Islet

描述(由申请人提供：本提案详细介绍了Scott Soleimanour医学博士的研究和培训计划，以发展他作为内科科学家的学术生涯，专注于彻底了解调节胰腺�细胞复制和生存的因素，最终目标是改进1型糖尿病的治疗。拟议的K08奖项的职业发展部分包括高级教学课程和正式的研究指导，由主要导师、宾夕法尼亚大学医学院医学副教授多丽丝·A·斯托弗斯(Doris A.Stoffers)和多学科指导委员会监督。宾夕法尼亚大学医学院提供了一个研究丰富的环境，开放访问各种专家教职人员和资源，这将有利于Soleimanour博士的科学和专业发展。在这项K08申请中提出的研究将集中在Clec16a(C-凝集素结构域家族16，成员A)，一个1型糖尿病易感基因和基本�细胞转录因子Pdx1的新靶点的�细胞特异性作用上。果蝇Clec16a的同源基因EMA是一种内体蛋白，通过与Vps-C-Hops复合体直接相互作用，调节内体和自噬体成熟过程中的关键转变，对内体成熟至关重要。EMA功能的丧失导致生长因子信号的增加，这是由于配体结合受体的清除减少而导致的突触终末过度生长。虽然Clec16a被认为仅限于免疫细胞表达，但我们的初步证据表明，Clec16a在小鼠和人类的胰岛中高表达。此外，功能丧失实验表明，Clec16a调节�细胞系的晚期内小体积累、细胞复制、胰岛素分泌和线粒体呼吸。因此，我们推测Clec16a在体内调节�-细胞内体途径以及�-细胞质量和功能的维持。具体目的1.检验Clec16a对�细胞质量和维持葡萄糖稳态至关重要的假说。这一目标将通过使用条件性Clec16a loxP等位基因在体内进行�细胞特异性功能丧失实验来确定Clec16a的作用。实验将集中于葡萄糖耐量和胰岛素分泌的测定，以及与�细胞增殖和/或存活变化相关的�细胞团的形态分析。具体目的II.检验Pdx1靶标Clec16a调节内噬菌体、自噬小体和线粒体功能的基本方面的假设。实验将确定Clec16a在内小体和自噬小体成熟、内小体运输、线粒体生物发生和钙流动中的作用。此外，还将确定Pdx1在调节Clec16a和�细胞内体途径中的上游调控作用。通过这些特定的目标，我们将建立一个新的Pdx1靶点在调节�-细胞质量和功能中的作用和作用机制。我们还将确定内体途径中的一个靶点对�细胞功能的重要性，包括胰岛素分泌、复制/存活、线粒体功能和自噬调节，这可能为未来的研究开辟一个新的领域。

DESCRIPTION (provided by applicant: This proposal details the research and training plan for Scott Soleimanpour, M.D. to develop his academic career as a physician-scientist focused on the thorough understanding of factors which regulate pancreatic �-cell replication and survival, with the eventual goal of improving treatment of type 1 diabetes. The career development portion of the proposed K08 award includes an advanced didactic curriculum and formal research mentoring under the supervision of the primary mentor, Doris A. Stoffers, M.D., Ph.D., Associate Professor of Medicine at the University of Pennsylvania School of Medicine, and a multi-disciplinary mentorship committee. The University of Pennsylvania School of Medicine offers a research-rich environment with open access to a wide assortment of expert faculty and resources that will be beneficial in the scientific and professional development of Dr. Soleimanpour. The research proposed in this K08 application will focus on the �-cell specific role of Clec16a (C-lectin domain family 16, member A), a type 1 diabetes susceptibility gene and novel target of the essential �-cell transcription factor Pdx1. The Drosophila orthologue of Clec16a, Ema, is an endosomal protein vital to endosomal maturation through direct interaction with the Vps-C HOPS complex, which regulates key transitions in endosome and autophagosome maturation. Loss of Ema function leads to increased growth factor signaling due to decreased clearance of ligand bound receptors with resultant synaptic terminal overgrowth. While Clec16a has been suggested to have restricted expression to immune cells, our preliminary evidence indicates that Clec16a is highly expressed in mouse and human islets. Further, loss of function experiments suggest that Clec16a regulates late endosome accumulation, cell replication, insulin secretion, and mitochondrial respiration in �-cell lines. Therefore, we hypothesize that Clec16a regulates the � -cell endosomal pathway and the maintenance of �-cell mass and function in vivo. Specific Aim I. To test the hypothesis that Clec16a is critical to �-cell mass and maintenance of glucose homeostasis. This aim will determine the role of Clec16a via �-cell specific loss-of-function experiments in vivo using a conditional Clec16a loxP allele. Experiments will focus on determinations of glucose tolerance and insulin secretion, as well as morphologic analysis of �-cell mass related to changes in � -cell proliferation and/or survival. Specific Aim II. To test the hypothesis that the Pdx1 target Clec16a regulates essential aspects of endosome, autophagosome, and mitochondrial function. Experiments will determine the role of Clec16a in endosomal and autophagosome maturation, endosomal trafficking, and mitochondrial biogenesis and calcium flux. In addition, the upstream regulatory role of Pdx1 in regulation of Clec16a and the � -cell endosomal pathway will be determined. Through these specific aims, we will establish the role and functional mechanism for a novel Pdx1 target in the regulation of � -cell mass and function. We will also determine the importance of a target in the endosomal pathway to � -cell function, including insulin secretion, replication/survival, mitochondrial function, and regulation of autophagy, that may open a new areas for future research.