Unraveling metabolic signaling in podocytes and its contribution to FSGS

线粒体除了作为细胞发电厂的经典功能外，最近已被认为是控制代谢信号通路的中央信号枢纽。受已知引起遗传性SRNS的一组核基因突变的启发，这些突变影响线粒体蛋白质，特别是辅酶Q10的生物合成，我们在第一个资助期内全面分析了肾小球足细胞的主要能量来源。有趣的是，足细胞在生理条件下主要通过独立于氧化磷酸化（OXPHOS）机制的无氧糖酵解维持其代谢平衡。这些发现挑战了我们对足细胞线粒体功能的看法。最近，我们描述了足细胞中线粒体功能和胰岛素信号传导之间的新联系：线粒体融合和分裂机制的损伤由线粒体蛋白OMA 1或PHB 2的表达丧失引起，导致包括AKT和营养传感器mTOR的胰岛素信号级联的过度激活。该项目的总体目标是获得机制的见解FSGS的发病机制中的线粒体信号和随后的代谢后果的失调的作用。为此目的，我们将（目的1）描绘功能障碍的线粒体采用Oma 1和Phb 2缺陷足细胞的代谢影响，在体外和体内。我们将进行广泛的代谢组学和蛋白质组学分析以及功能测定，以了解胰岛素和mTOR信号传导的具体贡献。在一个独立的方法（目标2），我们将专注于线粒体基因簇已知引起遗传性SRNS，我们将系统地研究辅酶Q10生物合成的影响足细胞和FSGS中的作用。我们利用我们新建立的类似于人类疾病的小鼠模型，通过对代谢组、蛋白质组和最终转录组的综合分析来解开足细胞特异性辅酶Q10信号传导网络（目的2）。最后（目标3），我们将把我们的发现转化为FOrMe登记研究中收集的MCD/FSGS患者的肾活检。在这里，我们将采用一种新的无偏见的MS/MS为基础的方法，使用肾小球组织从石蜡包埋切片的人肾活检，以及有针对性的方法，深入到代谢信号。其他有针对性的方法将使我们能够专注于代谢信号通路的贡献。

Mitochondria in addition to their classical function as cellular power plants have recently been recognized as central signaling hubs to control metabolic signaling pathways. Inspired by a cluster of nuclear gene mutations known to cause inherited SRNS which affect mitochondrial proteins and in particular co-enzyme Q10 biosynthesis, we comprehensively analyzed the primary sources of energy of glomerular podocytes within the first funding period. Interestingly, podocytes maintain their metabolic balance under physiological conditions primarily via anaerobic glycolysis independent of the oxidative phosphorylation (OXPHOS) machinery. These findings challenge our view on mitochondrial function in podocytes. Recently, we described a novel link between mitochondrial function and insulin signaling in podocytes: an impairment of the mitochondrial fusion and fission machinery caused by loss of the expression of the mitochondrial proteins OMA1 or PHB2 resulted in an overactivation of the insulin signal cascade comprising AKT and the nutrient-sensor mTOR. The overarching goal of this project is to gain mechanistic insights into the role of deregulated mitochondrial signaling and subsequent metabolic consequences in the pathogenesis of FSGS. For this purpose, we will (Aim 1) delineate the metabolic impact of dysfunctional mitochondria employing Oma1 and Phb2 deficient podocytes both, in vitro and in vivo. We will perform extensive metabolomic and proteomic analyses as well as functional assays to understand the specific contributions of insulin and mTOR signaling. In an independent approach (Aim 2), we will focus on the mitochondrial gene cluster known to cause inherited SRNS and we will systematically study the impact of co-enzyme Q10 biosynthesis in podocytes and the role in FSGS. We make use of our newly established mouse models resembling the human disease to unravel podocyte-specific co-enzyme Q10 signaling networks by a comprehensive analysis of the metabolome, proteome and ultimately transcriptome (Aim 2). Finally (Aim 3), we will translate our findings to renal biopsies of patients with MCD/FSGS collected in the FOrMe registry. Here, we will employ a novel unbiased MS/MS based approach using glomerular tissue from paraffin embedded sections of human kidney biopsies as well as a targeted approach to go deeper into metabolic signaling. Additional targeted approaches will allow us to focus on the contribution of metabolic signaling pathways among others.