DNA damage response pathways in podocytes: novel targets to treat focal segmental glomerulosclerosis

积累的DNA损伤和DNA损伤反应信号的改变在衰老过程中起着基础性作用，并导致一系列与衰老相关的疾病。对于终末分化的肾小球足细胞来说，功能的维持，包括其基因组的持续修复，对细胞的生存至关重要。因此，我们最近发现了早衰症相关基因ERCC1，该基因编码DNA核苷酸切除修复(NER)中的一个关键酶，以对抗肾小球衰老。全基因组转录组分析揭示了14周龄复合杂合子小鼠肾小球老化的特征，这些小鼠携带ERCC1功能丧失和亚型等位基因(ERCC1-/Δ)。随后，我们获得了足细胞特异性ERCC1基因敲除小鼠模型(Ercc1pko)。这些小鼠表现出严重的足细胞功能障碍和局灶节段性肾小球硬化(FSGS)的组织学证据。根据我们以前的数据，我们假设足细胞中DNA损伤的积累在老年人FSGS的发展中起着基础性作用。这一建议的首要目标是了解DNA损伤反应(DDR)信号如何影响足细胞的动态平衡和存活的机制，以及该网络的改变如何导致FSGS。具体地说，我们的目标是(1)利用小鼠模型和线虫描述DNA损伤信号和对足细胞动态平衡至关重要的已知通路之间的串扰，(2)揭示DDR信号和DDR预适应在实验性FSGS小鼠模型中的影响，以及(3)研究mTOR抑制、热量限制和细胞衰老在DDR相关FSGS中的作用。我们期望这个项目将大大提高对与年龄相关的FSGS的了解，并导致确定潜在的药物干预的新靶点。

Accumulating DNA damage and alterations in DNA damage response signaling play fundamental roles in the aging process and contribute to a wide range of aging-associated diseases. For terminally differentiated glomerular podocytes functional maintenance including the continuous repair of their genome is of great importance for cellular survival. Accordingly, we recently identified the progeria-associated gene Ercc1, coding for a key enzyme in DNA nucleotide excision repair (NER), to counteract glomerular aging. Genome-wide transcriptome analyses revealed the signature of aged glomeruli in 14 week-old compound heterozygous mice harboring a loss-of-function and a hypomorphic allele of Ercc1 (Ercc1-/Δ). Subsequently, we have generated a podocyte-specific Ercc1 knockout mouse model (Ercc1pko). These mice display severe podocyte dysfunction and histologic evidence of focal segmental glomerulosclerosis (FSGS). Based on our previous data we hypothesize that accumulation of DNA damage in podocytes plays a fundamental role in the development of FSGS in the elderly. The overarching goal of this proposal is to understand the mechanisms how DNA damage response (DDR) signaling affects podocyte homeostasis and survival and how alterations of this network lead to FSGS. Specifically, we aim (1) at delineating the crosstalk between DNA damage signaling and known pathways crucial for podocyte homeostasis using mouse models and C. elegans, (2) at unraveling the impact of DDR signaling and DDR preconditioning in experimental mouse models of FSGS, and (3) at investigating the role of mTOR inhibition, caloric restriction and cellular senescence in DDR-related FSGS. We expect that this project will significantly enhance the understanding of age-related FSGS and lead to the identification of novel targets potentially amenable to pharmacological interventions.