Altered cellular compartmentalization as a potential pathomechanism driving CKD.

最近由Antonin发现的核孔复合体（NPC）蛋白的基因突变导致人类足细胞病变和足细胞丢失，导致局灶性和节段性肾小球硬化（FSGS）和慢性肾脏疾病（CKD）。NPCs调节核质和细胞质的基本运输，从而调节这些区室之间蛋白质的分布。在神经元中，当npc发生突变时，这种蛋白质分布受损，但这也发生在疾病和生理衰老过程中。足细胞是肾脏中的一种关键细胞，它不能被替换，也不能分裂——类似于神经元。在大多数肾小球疾病以及生理性衰老中，足细胞的丢失原因尚不清楚。在这里，我们将探讨在生理性衰老和肾小球疾病中，鼻咽癌功能不足或受损导致的蛋白质错误定位是否与足细胞的丢失有关。为此，我们将1.)检验核细胞质蛋白比（NCR）作为诊断工具的价值。我们将通过免疫染色检查老年小鼠足细胞中已知的核和细胞质标记蛋白的分布，以及遗传形式FSGS的大鼠菌株以及人类活组织检查。2)从转基因小鼠中分离足细胞，分析亚细胞蛋白质组学，以鉴定在衰老或肾小球疾病中核质比受损的新蛋白。3)在原代足细胞的体外实验中，开发方法来操纵细胞核和细胞质之间的蛋白质分布，并恢复有缺陷的核/细胞质区隔。4)在大鼠和小鼠模型中测试这些操作是否可以改善疾病进展并预防CKD。5)研究NCR和区隔化丧失在肾小管室中的潜在作用，特别是在衰老小鼠的近端小管细胞和急性肾损伤中。总之，我们将分析最近在足细胞中发现的鼻咽癌渗透性受损的新病理机制的相关性，这种机制在表型上导致进行性足细胞丢失和随后的FSGS。我们将研究其诊断效用，其与生理衰老和急性肾损伤阶段转变为CKD的相关性，并旨在首次在小鼠和大鼠模型中进行药物干预。

Genetic mutations in proteins of the nuclear pore complex (NPC) recently identified by Antonin cause podocytopathy and podocyte loss in humans, resulting in focal and segmental glomerulosclerosis (FSGS) and chronic kidney disease (CKD). NPCs regulate the essential transport nucleoplasm and cytoplasm and hence the distribution of proteins between these compartments. In neurons, this protein distribution is impaired when NPCs are mutated, but this also occurs in disease and during physiological aging. The podocyte is a critical cell in the kidney, which cannot be replaced and cannot divide - similar to neurons. In most glomerular diseases as well as in physiological aging, podocytes are lost for yet unknown reasons. Here, we will explore whether an insufficient or impaired NPC function leading to protein mislocalization is associated with the loss of podocytes in physiological aging and in glomerular disease. For this we will1.) test the value of nuclear-cytoplasmic protein ratio (NCR) as diagnostic tool. We will examine by immunostainings the distribution of known nuclear and cytoplasmic marker proteins in podocytes in aged mice and in a rat strain with a genetic form of FSGS as well as in human biopsies. 2.) isolate podocytes from transgenic mice to analyze the subcellular proteomes to identify novel proteins with an impaired nuclear to cytoplasmic ratio in aging or glomerular disease. 3.) develop methods to manipulate protein distribution between the nucleus and cytoplasm in established in-vitro assays in primary podocytes and restore defective nuclear/cytoplasmic compartmentalization. 4.) test in rat and mouse models whether these manipulations can ameliorate disease progression and prevent CKD. 5.) examine a potential role of the NCR and loss of compartmentalization also in the tubular compartment of the kidney, specifically in proximal tubular cells of aging mice as well as in acute kidney injury.In conclusion, we will analyze the relevance of a novel pathomechanism of an impaired NPC permeability recently identified in podocytes, which phenotypically results in progressive podocyte loss and subsequent FSGS. We will investigate its diagnostic utility, its relevance for phase transition to CKD in physiological aging and acute kidney injury and aim for the first pharmacological interventions in mouse and rat models.