Cell Cycle and Metabolism in Chronically Injured Renal Tubules

慢性肾脏疾病（CKD）影响了几乎15%的美国人，肾损伤通常以肾小管为目标 上皮细胞这些小管如何反应可以决定肾脏是否经历修复或肾小管间质损伤。 纤维化（TIF），进行性CKD的共同标志。该提案的重点是了解慢性 肾损伤诱导肾小管细胞周期和代谢的变化，以及这些变化如何影响 肾小管存活和TIF的发展。众所周知，细胞周期、代谢和线粒体 功能都是密切协调的过程，但尚不清楚上皮细胞G1到S细胞周期的进展 影响CKD肾脏的代谢。初步数据表明，从G1期开始减少细胞周期进展， 在啮齿类CKD模型中，肾小管中的S期保护免于纤维化并减少肾小管细胞凋亡。在 此外，减少G1至S进程增加了葡萄糖氧化，葡萄糖代谢为丙酮酸 然后通过柠檬酸循环和电子传递链在线粒体中被氧化。这 该提案将检验减少CKD中上皮细胞G1期至S期进展可保护 通过改变代谢来对抗上皮损伤和纤维化。为了测试这一点，Aim 1将使用 药理学（palbociclib）或遗传学（条件性删除肾小管细胞周期蛋白D1）方法降低G1 小鼠的S细胞周期进展。我们假设，上皮细胞G1期向S期的进展减少， 细胞通过减少肾小管损伤和纤维化在CKD模型中具有保护作用。初步数据显示， 在损伤的肾组织和分离的肾小管细胞中减少细胞周期进程也抑制了 信号通路和炎症细胞因子与肾损伤相关。这一目标调查如何 减少细胞周期进程可以改变这些信号通路，以减少肾小管损伤和肌成纤维细胞 分别通过自分泌和旁分泌信号传导激活。第二个目的是研究代谢 使用Seahorse bioflux时，受损肾小管中发生的变化，G1期至S期进展减少 分析仪、离体14 C-丙酮酸氧化研究和稳定同位素代谢组学。我们假设 减少上皮细胞周期进程增加葡萄糖氧化，导致更好的上皮存活， 减少纤维化，部分是通过AMP激活的蛋白激酶途径。我们还将研究葡萄糖 肾小管中的氧化不依赖于代谢，影响对慢性损伤的反应。细胞的影响 线粒体功能和结构的周期进展也将使用Oroboros和超 分辨率显微镜这些研究应该提供新的信息， 循环和代谢影响对慢性肾损伤的反应， 治疗CKD的治疗靶点。

Chronic kidney disease (CKD) affects almost 15% of Americans, and renal injury often targets the renal tubule epithelia. How these tubules respond can determine whether the kidney undergoes repair or tubulointerstitial fibrosis (TIF), the common hallmark of progressive CKD. This proposal focuses on understanding how chronic renal injury induces changes in the renal tubular cell cycle and metabolism and how these changes affect tubular survival and the development of TIF. It is well known that cell cycle, metabolism, and mitochondrial function are all closely coordinated processes, but it is not clear how epithelial G1 to S cell cycle progression affects metabolism in the CKD kidney. Preliminary data suggests that reducing cell cycle progression from G1 to S phase in renal tubules protects against fibrosis in rodent CKD models and decreases tubular apoptosis. In addition, reducing G1 to S progression increased glucose oxidation, the metabolism of glucose to pyruvate which is then oxidized in the mitochondria through the citric acid cycle and electron transport chain. This proposal will test the hypothesis that reducing epithelial G1 to S phase progression in CKD protects against epithelial injury and fibrosis through altered metabolism. To test this, Aim 1 will use either a pharmacologic (palbociclib) or a genetic (conditionally delete cyclin D1 in renal tubules) approach to reduce G1 to S cell cycle progression in mice. We hypothesize that decreasing G1 progression to S phase in epithelial cells is protective in CKD models by reducing tubular injury and fibrosis. Our preliminary data show that reducing cell cycle progression in both injured kidney tissue and in isolated tubule cells also suppresses signaling pathways and inflammatory cytokines associated with kidney injury. This aim investigates how reducing cell cycle progression may alter these signaling pathways to reduce tubule injury and myofibroblast activation by autocrine and paracrine signaling, respectively. The second aim investigates the metabolic changes that occur in injured tubules with reduced G1 to S phase progression using the Seahorse bioflux analyzer, 14C-pyruvate oxidation studies ex vivo, and stable isotopic metabolomics. We hypothesize that reducing epithelial cell cycle progression increases glucose oxidation leading to better epithelial survival and less fibrosis, in part, through the AMP-activated protein kinase pathway. We will also investigate how glucose oxidation in renal tubules, independent of metabolism, affects the response to chronic injury. The impact of cell cycle progression on mitochondrial function and structure will also be defined using Oroboros and super- resolution microscopy. These studies should provide novel information about how changes in epithelial cell cycle and metabolism affect the response to chronic renal injury with the potential identification of novel therapeutic targets to treat CKD.