Genetic Control of Ureter and Kidney Development

输尿管和肾脏发育的遗传控制

• 批准号: 7817573
• 负责人: FRANKLIN D COSTANTINI
• 金额: $ 49.77万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-25 至 2011-09-24
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7817573
• 关键词: Ablation; Address; Affect; Alleles; Cell Count; Cell Lineage; Cells; Clinical; Complement; Cues; Data; Defect; Development; Dose; Duct (organ) structure; Ductal Epithelium; Epithelium; Fetal Development; Funding; GDNF gene; Genes; Genetic; Growth; Growth and Development function; Hand; Hypertension; Kidney; Kidney Diseases; Lead; Life; Ligands; Link; Liver; Mesenchyme; Metanephric Diverticulum; Morphogenesis; Mus; Mutation; Nephrons; Occupations; Organ; Organ Culture Techniques; Organ Size; Pancreas; Receptor Protein-Tyrosine Kinases; Regulation; Research Personnel; Role; Services; Signal Transduction; Staging; Stem cells; Tamoxifen; Testing; Time; Ureter; cell killing; collecting tubule structure; cytotoxic; diphtheria toxin fragment A; in vivo; kidney cell; killings; nephrogenesis; postnatal; progenitor; programs; public health relevance; receptor; recombinase; research study

DESCRIPTION (provided by applicant): Little is known about the developmental mechanisms that determine the size of the kidney and the number of nephrons. Why does the kidney grow to a particular size and complexity, and then stop? Is there an intrinsic limitation in the number of divisions of progenitor cells, or is organ size regulated by some other mechanism, such as external signals? In this Revision application, we propose new experiments to address these questions. Two major renal cell lineages are the collecting duct epithelia, which derive from the ureteric bud, and the nephron epithelia, which derive from the metanephric mesenchyme. Cells expressing the Ret receptor, located at the tips of the ureteric bud, are the major progenitors of collecting ducts, while metanephric mesenchyme cells expressing the Ret- ligand GDNF are the progenitors of nephron epithelia. We will use mice expressing an inducible form of Cre recombinase (Cre-ERT2) under the control of the Ret or Gdnf genes. These mice will be crossed with a strain that conditionally expresses a cytotoxic gene, DTA, only in cells that express active Cre, and in their descendants. By inducing Cre activity with Tamoxifen, we will selectively reduce the number of the progenitor cells in the ureteric bud or metanephric mesenchyme, at specific stages of kidney development. We will then analyze the kidneys in vivo and in organ culture, to ask if this alters the rates of ureteric bud growth and nephrogenesis, and the final kidney size and nephron number. If the progen- itors are programmed to divide a limited number of times, then destroying a fraction of them should result in decreased organ size. Alternatively, if these cells have excess proliferative capacity and are regulated by external signals, the organ may recover and reach its normal size. Either the number of ureteric bud or nephron progenitor cells, or both, might limit the growth rate and final size of the kidney. Our experiments also address the basic question of whether tip cell number might determine the rates of elongation and branching of the ureteric bud, and similarly, how the number of nephron progenitors might affect the rate of formation and the size of nephrons. Understanding how the kidney achieves its normal size and nephron number has very important clinical implications, as reduced nephron number may favor the progression of renal diseases and hypertension. The proposed studies expand the scope of our original project (whose Aims concern the regulation of kidney development by growth factors, tyrosine kinase receptors, and intracellular signaling mechanisms) to include studies on the role of progenitor cells in kidney growth and development. It will allow for job creation by providing the funds to hire new postdoctoral researchers, and to purchase additional supplies and services. PUBLIC HEALTH RELEVANCE: Understanding how the kidney achieves its normal size has important clinical implications, as defects in organ growth during fetal development can lead to a reduction in the number of nephrons, the filtering units. This, in turn, may promote the progression of renal diseases and hypertension. This proposal investigates the mechanisms that control how the kidney grows to the correct size, and how the proper number of nephrons is formed.

描述（由申请人提供）：关于确定肾脏大小和肾单位数的发育机制知之甚少。为什么肾脏会长到特定的大小和复杂性，然后停止？祖细胞的分裂数量是否存在固有的限制，或者器官大小受某些其他机制（例如外部信号）调节？在此修订应用程序中，我们提出了新的实验来解决这些问题。两个主要的肾细胞谱系是源自输尿管芽的收集导管上皮，而肾上腺上皮源则来自元素间充质。表达RET受体的细胞位于输尿管芽的尖端，是收集管道的主要祖细胞，而表达Ret-ligand gdnf的肾上腺素间充质细胞是Nephron上皮elia的祖细胞。我们将使用在RET或GDNF基因控制下表达CRE重组酶（CRE-ERT2）的诱导形式的小鼠。这些小鼠将与有条件表达细胞毒性基因DTA的菌株仅在表达活性CRE的细胞及其后代中的细胞。通过使用他莫昔芬诱导CRE活性，我们将在肾脏发育的特定阶段有选择地减少输尿管芽或跨词间质的祖细胞的数量。然后，我们将分析体内和器官培养中的肾脏，询问这是否改变了输尿管芽生长和肾脏形成的速率，以及最终的肾脏大小和肾单位数。如果对后代进行编程以划分有限的次数，那么破坏其中的一部分应导致器官尺寸减小。或者，如果这些细胞具有过多的增殖能力，并且受外部信号调节，则器官可能会恢复并达到其正常大小。输尿管芽的数量或肾单位祖细胞的数量，或两者都可能限制肾脏的生长速率和最终大小。我们的实验还解决了尖端细胞数是否可能决定输尿管芽的伸长率和分支的基本问题，同样，肾单位祖细胞的数量如何影响形成速率和肾脏的大小。了解肾脏如何实现其正常大小和肾单位数具有非常重要的临床意义，因为减少的肾单位数可能有利于肾脏疾病和高血压的进展。拟议的研究扩大了我们原始项目的范围（其目的涉及生长因子，酪氨酸激酶受体和细胞内信号传导机制对肾脏发育的调节），以包括有关祖细胞在肾脏生长和发育中的作用的研究。它将通过提供资金来聘请新的博士后研究人员并购买其他用品和服务来创造就业机会。 公共卫生相关性：了解肾脏如何实现其正常大小具有重要的临床意义，因为胎儿发育过程中器官生长的缺陷会导致肾单位数量减少，即过滤单元。反过来，这可能会促进肾脏疾病和高血压的进展。该提案研究了控制肾脏如何生长到正确尺寸的机制，以及如何形成适当数量的肾单位。