Identification of genetic pathways that regulate kidney cell fate: Hand2 inhibits intermediate mesoderm development

项目总结 首席研究员寻求指导培训以研究早期肾脏的基因调控 利用斑马鱼胚胎进行发育。研究和培训将在博士的实验室进行。 Deborah Yelon，加州大学旧金山分校儿科肾病学部的支持 迭戈和由肾脏发育和疾病专家组成的咨询委员会以及 器官形成的遗传调控。目标是获得培训并进行实验室研究，以 将导致首席调查员发展成为一名独立的内科科学家。的总目标是 这项研究旨在阐明调节肾脏早期发育的遗传途径，以便 深入了解肾脏出生缺陷的病因，并指导再生医学的策略。去做 因此，PI将利用斑马鱼作为模型的遗传和胚胎学优势 有机体。与哺乳动物的肾脏一样，斑马鱼的肾脏来自中间中胚层。工作 在包括斑马鱼在内的多种生物中，已经定义了几个促进IM形成的保守因子。 然而，定义IM与其邻近领土区分的边界的机制是 还不能理解。PI最近的研究表明，bHLH转录因子Hand2定义了 通过调节后中胚层内细胞命运的决定来调节IM的侧缘。当即时消息和 胚胎肾脏在hand2突变体中扩张，hand2过表达导致IM和 肾脏发育。此外，Hand2在位于外侧的后中胚层部分也有表达。 与IM相邻。静脉祖细胞在这两个区域之间产生，而hand2促进静脉 在此界面上抑制IM形成的同时，祖细胞发育。外侧的HAND2表达区域 还表达之前参与促进肾脏形成的锌指转录因子osr1，以及 遗传分析表明，Hand2和osr1在肾脏发育过程中具有功能拮抗作用。 总而言之，这些数据揭示了一个以前未被识别的、调节IM边界的遗传网络， 提出了一种模型，在该模型中，Hand2的功能与osr1相反，以控制祖细胞分配到 肾脏和静脉血统。为了测试这一模型，将追求两个具体目标。第一个目标将定义角色 对HAND2中抑制IM谱系的规范，采用高分辨率命运图分析和细胞自主性 学习。第二个目标是确定Hand2和osr1控制IM的途径中的基因 规范，使用互补候选基因和整个转录组方法来识别相关的 伙伴和效应器基因。这些研究将阐明Hand2在IM形成中的作用，并阐明 通过平衡肾和静脉谱系的形成来定义IM的边界的通路。超过了 从长远来看，对这些遗传途径的详细理解应该会改善诊断、预后和 肾脏疾病患者的治疗选择。

PROJECT SUMMARY The Principal Investigator seeks mentored training to investigate the genetic regulation of early kidney development using the zebrafish embryo. Research and training will be carried out in the laboratory of Dr. Deborah Yelon, with the support of the Division of Pediatric Nephrology at the University of California, San Diego and an advisory committee composed of specialists in kidney development and disease and in the genetic regulation of organ formation. The objective is to obtain training and pursue laboratory research that will lead to the Principal Investigator's development into an independent physician-scientist. The overall goal of the research is to elucidate the genetic pathways regulating early stages of kidney development in order to gain insight into the etiology of kidney birth defects and to instruct strategies in regenerative medicine. To do so, the PI will take advantage of the genetic and embryological benefits of using the zebrafish as a model organism. Like mammalian kidneys, zebrafish kidneys are derived from the intermediate mesoderm (IM). Work in multiple organisms, including zebrafish, has defined several conserved factors that promote IM formation. However, the mechanisms defining the boundaries that distinguish the IM from its neighboring territories are not yet understood. Recent studies by the PI suggest that the bHLH transcription factor Hand2 defines the lateral border of the IM by regulating cell fate decisions within the posterior mesoderm. While the IM and embryonic kidney are expanded in hand2 mutants, hand2 overexpression results in strong inhibition of IM and kidney development. Additionally, hand2 is expressed in a portion of the posterior mesoderm that lies laterally adjacent to the IM. Venous progenitors arise between these two territories, and hand2 promotes venous progenitor development while inhibiting IM formation at this interface. The lateral hand2-expressing territory also expresses osr1, a zinc-finger transcription factor previously implicated in promoting kidney formation, and genetic analyses suggest that hand2 and osr1 have functionally antagonistic roles during kidney development. Together, these data shed light on a previously unrecognized genetic network that regulates IM boundaries, suggesting a model in which hand2 functions in opposition to osr1 to control the allocation of progenitor cells to kidney and vein lineages. To test this model, two specific aims will be pursued. The first aim will define the role of hand2 in the inhibition of IM lineage specification, using high-resolution fate map analysis and cell autonomy studies. The second aim will identify genes in the pathways through which hand2 and osr1 control IM specification, using complementary candidate gene and whole transcriptome approaches to identify relevant partner and effector genes. These studies will elucidate the role of hand2 in IM formation and illuminate the pathways that define the boundaries of the IM by balancing formation of the kidney and vein lineages. Over the long term, detailed comprehension of these genetic pathways should improve diagnostic, prognostic, and therapeutic options for patients with kidney disease.