背景:常染色体显性肾小管间质性肾病(ADTKD)是由各种基因的突变引起的,包括REN,UMOD,MUC1和HNF1B。由于REN突变(ADTKD-REN)导致的ADTKD通常被表征为触发内质网应激(ERS)级联的蛋白质病。在细胞水平上可能与ADTKD-UMOD和ADTKD-MUC1共享相似性。这项研究,灵感来自一个有W17R突变的病人,调查ERS通过这种突变以及其他两种肾素变体激活,W10R和L381P。
方法:我们建立了表达野生型和突变肾素形式的稳定细胞系(W17R,W10R,和L381P)。使用荧光素酶报告基因测定,RT-qPCR,和共聚焦显微镜,我们评估了ERS激活,确定肾素变体的细胞定位,并表征了W17R系中的线粒体网络。
结果:L381P线显示ERS激活,包括MANF和CRELD2的转录上调。在W17R系中没有观察到ERS激活,而W10R线表现出中间特性。值得注意的是,W17R变异体被误导至线粒体,导致线粒体网络组织发生变化.
结论:ERS激活不是对ADTKD-REN中不同肾素突变的普遍反应。W17R突变的发病机制可能涉及线粒体功能障碍,而不是ER通路。尽管需要进一步的研究来充分证实这一假设。建议测试CRELD2和MANF作为ADTKD-REN患者特定亚组的靶向治疗标志物。此外,氟氢可的松治疗已显示出在四年期间稳定我们患者的肾功能的疗效,而没有明显的副作用。
BACKGROUND: Autosomal dominant tubulointerstitial kidney disease (ADTKD) results from mutations in various genes, including REN, UMOD, MUC1, and HNF1B. ADTKD due to REN mutations (ADTKD-REN) is often characterized as a proteinopathy that triggers the endoplasmic reticulum stress (ERS) cascade, potentially sharing similarities with ADTKD-UMOD and ADTKD-MUC1 at the cellular level. This study, inspired by a patient harboring a W17R mutation, investigates ERS activation by this mutation alongside two other renin variants, W10R and L381P.
METHODS: We established stable cell lines expressing both wild-type and mutated renin forms (W17R, W10R, and L381P). Using luciferase reporter assays, RT-qPCR, and confocal microscopy, we evaluated ERS activation, determined the cellular localization of the renin variants, and characterized the mitochondrial network in the W17R line.
RESULTS: The L381P line exhibited ERS activation, including transcriptional upregulation of MANF and CRELD2. No ERS activation was observed in the W17R line, while the W10R line exhibited intermediate characteristics. Notably, the W17R variant was misrouted to the mitochondria resulting in changes of the mitochondrial network organisation.
CONCLUSIONS: ERS activation is not a universal response to different renin mutations in ADTKD-REN. The pathogenesis of the W17R mutation may involve mitochondrial dysfunction rather than the ER pathway, albeit further research is needed to substantiate this hypothesis fully. Testing CRELD2 and MANF as targeted therapy markers for a specific subgroup of ADTKD-REN patients is recommended. Additionally, fludrocortisone treatment has shown efficacy in stabilizing the renal function of our patient over a four-year period without significant side effects.