DEVELOPMENTAL ROLE OF THE GENE SIX2 IN KIDNEY NEPHRON ENDOWMENT

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 肾脏发育不佳导致先天肾单位数量不足 终生后果，并与心血管-肾脏疾病的重大风险相关 在晚年，与那些出生时具有典型肾单位天赋的人相比。长期目标 目前的提议是确定驱动成功的肾单位的细胞机制 分化以达到最佳的肾单位赋能。具体地说，我们将探索 同源异型盒基因SIX2，并确定SIX2是否参与了 肾脏器官发生过程中肾单位数目的建立。使用RNAi方法， 实验旨在确定SIX2转录的早期失活 肾形成导致输尿管芽生长显著减少，因此肾单位 器官型肾脏外植体培养中的数量。此外，使用可遗传的小鼠模型 发育过程中缺乏足够表达SIX2的肾脏发育不良(短臂) (BR)突变小鼠)，我们将采取系统的方法将SIX2重新引入肾脏 从BR小鼠制备的外植体，并确定外源SIX2是否刺激 输尿管芽的分枝导致肾单位的增加。此外，我们 将含有SIX2基因的250kb Bac基因整合到BR小鼠基因组中，试图 增加肾单位数目，从而挽救与肾脏表型相关的缺陷 SIX2缺乏症。在抢救之后，我们将评估肾脏生理特征是否 在成年BR小鼠体内修复。这项提议将利用BR小鼠品系 显示SIX2基因表达的单倍性不足，是 世界。同样，我们已经充分描述了成年BR小鼠的生理学特征 显示高血压和慢性肾功能衰竭促进我们的表型抢救 实验。当综合考虑时，这些实验将提供基本的 构成SIX2基因基础的肾脏形态发生和特异性 确定SIX2是否直接决定发育中的肾脏中肾单位的捐赠。 这项研究的结果也将强调SIX2在可能的肾单位中的重要性 成人病变肾脏的修复方法。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Suboptimal kidney development resulting in an in-born deficit in nephron number can have lifelong consequences and is associated with a significant risk of cardiovascular-renal disease in later life, compared to those born with a typical nephron endowment. The long-term goal of the current proposal is to identify cellular mechanisms that drive successful nephron differentiation to achieve optimal nephron endowment. Specifically, we will explore the roles of the homeobox gene sine oculis 2 (six2), and determine whether six2 is involved in the establishment of nephron number during kidney organogenesis. Using an RNAi methodology, experiments are designed to determine whether inactivation of six2 transcription early in nephrogenesis results in a significant decrease in ureteric bud growth and, therefore, nephron number in an organotypic kidney explant culture. Further, using a mouse model of heritable renal hypoplasia that lacks sufficient expression of six2 during development (the Brachyrrhine (Br) mutant mouse), we will take a systematic approach to re-introduce six2 to kidney explants that are prepared from Br mice and determine if exogenous six2 stimulates branching of the ureteric buds leading to an enhanced nephron production. Additionally, we will incorporate a 250 kb Bac containing six2 gene into the Br mouse genome to attempt to increase nephron number and, thereby rescuing the defective renal phenotype associated with six2 deficiency. Following the rescue we will assess if renal physiological features are restored in the adult Br mouse. This proposal will take advantage of the Br mouse strain that displays haploinsufficiency of six2 gene expression and is the only working colony in the world. Similarly, we have fully characterized the physiology of the adult Br mouse that demonstrates hypertension and chronic renal failure facilitating our phenotypic rescue experiments. When considered together, these experiments will provide the fundamental insights that constitute the genetic basis of six2 in renal morphogenesis and specifically establish whether six2 directly determines nephron endowment in the developing kidney. Results from this study will also underscore the importance of six2 in possible nephron restoration approaches in the adult diseased kidney.