Reduced Glomerular Progenitors Impair Regeneration in Aged Kidney

一般人口的寿命越来越长，这就需要更好地了解老龄化对人类健康的影响。 器官结构和功能。肾功能受损在老年人中更为常见， ESRD在> 65岁的人群中不成比例地增加。这项拨款提案的目标是确定新的 衰老肾脏变化的潜在机制，重点是肾小球，特别是两者 肾小球上皮细胞类型。肾脏衰老的典型表现是足细胞的进行性耗竭， 导致肾小球硬化和肾功能下降。终末分化 上皮细胞，称为足细胞（podo），不能充分增殖，因此不能取代 自己最近，大量令人信服的文献表明，在年轻成人和中年肾脏中， 邻近的肾小球壁上皮细胞（佩奇）的亚群充当成体足祖细胞。我们 最近报道佩奇也受老化的影响;特征是PEC总数减少， 剩余细胞的亚群变得衰老或经历间充质转化。这 赠款提案将研究现有的与年龄相关的podo耗尽问题，但在一个全新的背景下， 通过解决衰老肾脏中PEC祖细胞的主要知识空白及其无法充分 补充能量。新方法将包括我们最近开发的双PEC-podo报告小鼠， 使用诱导型PEC单独标记和谱系追踪同一肾小球内的佩奇和足 祖细胞报告小鼠，以及原代佩奇在来源于高龄报告小鼠的培养物中的用途。 目标1将确定PEC祖细胞数量何时以及以何种速度随着年龄的增长而减少，并将 测试进行性细胞衰老是PEC祖细胞减少的主要原因的假设， 衰老我们将证明，通过降低衰老，PEC祖细胞数量将更高，伴随着 更高的足细胞密度。目的2证明老年小鼠PEC祖细胞的自我更新能力较低 与年轻的小鼠相比，无论是在动物的生命周期中慢性地，还是在对突然的 实验FSGS中足细胞数量的下降。研究将检验老化PEC增殖是一个重要因素的假设。 由于细胞周期抑制剂p21和p16的重新增加而减少，这是继发于 增加氧化应激。目的3将显示老化的PEC祖细胞具有较低的转分化 能力对podo的命运，并测试假设，这是部分由于重新编程的一个子集 老化的佩奇的间充质命运，从而限制了他们的能力转分化成成年足。我们 预计结果将为一个新的范式提供令人信服的证据和候选机制， PEC祖细胞的生物学和功能作用在老化的肾脏中显著改变，从而导致它们的 无法补充足细胞。这些研究将为肾小球重要的功能改变提供证据， 上皮细胞，这是老年肾脏有害变化的基础。

The general population is living longer, precipitating the need to better understand the effects of aging on organ structure and function. Impaired kidney function is more common in the elderly, and the incidence of ESRD is increasing disproportionately in people > 65yrs. The goal of this grant proposal is to identify novel mechanisms underlying changes in the aging kidney, with a focus on the glomerulus, in particular both glomerular epithelial cell types. Kidney aging is typified by a progressive depletion of podocytes, which directly underlies the development of glomerulosclerosis and reduced kidney function. Terminally differentiated epithelial cells, called podocytes (podo) are unable to adequately proliferate, and therefore cannot replace themselves. Recently a large and compelling literature shows that in young adult and middle-aged kidneys, a subpopulation of neighboring glomerular parietal epithelial cells (PECs) serves as adult podo progenitors. We recently reported that PECs are also affected by aging; characterized by a decrease in total PEC number, with subpopulations of the remaining cells becoming senescent or undergoing mesenchymal transformation. This grant proposal will study the existing problem of age-related podo depletion, but in a completely new context, by addressing major knowledge gaps of PEC progenitors in the aging kidney and their inability to adequately replenish podo. New approaches will include our recently developed dual PEC-podo reporter mice that individually label and lineage trace PECs and podos within the same glomerulus, the use of an inducible PEC progenitor reporter mouse, and the use of primary PECs in culture derived from reporter mice of advanced age. Aim 1 will establish when, and at what rate, PEC progenitor number decreases with advancing age, and will test the hypothesis that progressive cellular senescence is a major cause of reduced PEC progenitors with aging. We will prove that by lowering senescence, PEC progenitor number will be higher, accompanied by higher podocyte density. Aim 2 will prove that the self-renewal of PEC progenitors is lower in aged mice compared to young mice, both chronically over the life span of the animal, and acutely in response to an abrupt decline in podo number in experimental FSGS. Studies will test the hypothesis that aged PEC proliferation is reduced due to de novo increases of the cell cycle inhibitors p21 and p16, and that this is secondary to increased oxidative stress. Aim 3 will show that aged PEC progenitors have a lower transdifferentiation capacity towards a podo fate, and test the hypothesis that this is in part due to the reprogramming of a subset of aged PECs to a mesenchymal fate, thereby limiting their ability to transdifferentiate into adult podos. We anticipate that the results will provide compelling evidence and candidate mechanisms for a new paradigm that the biology and functional roles of PEC progenitors are markedly altered in aged kidneys thus, leading to their inability to replenish podos. These studies will provide evidence for important functional changes in glomerular epithelial cells, which underlie detrimental changes in aged kidneys.