Differences in renal cortex transcriptional profiling of wild-type and novel type B cystinuria model rats

Cystinuria is a genetic disorder of cystine transport that accounts for 1–2% of all cases of renal lithiasis. It is characterized by hyperexcretion of cystine in urine and recurrent cystine lithiasis. Defective transport of cystine into epithelial cells of renal tubules occurs because of mutations of the transport heterodimer, including protein b0,+AT (encoded by SLC7A9) and rBAT (encoded by SLC3A1) linked through a covalent disulfide bond. Study generated a novel type B cystinuria rat model by artificially deleting 7bp of Slc7a9 gene exon 3 using the CRISPR-Cas9 system, and those Slc7a9-deficient rats were proved to be similar with cystinuria in terms of genome, transcriptome, translation, and biologic phenotypes and typical secondary changes as medullary fibrosis. Study then established the first transcription database of type B cystinuria based on this novel cystinuria rat model. In accordance with the functional annotation of DEGs, the potential role of glutathione metabolism processes in kidney of cystinuria rat model was proposed, and KEGG analysis results showed that knock-out of Slc7a9 gene triggered more biological changes which has not been study. This rat model and its transcriptional database that mimics the pathogenesis and clinical consequences of human type B cystinuria was generated for a better understanding of pathophysiological mechanism underlying in cystinuria that can be used to provide references when looking for new target and strategies for reducing kidney damage of cystinuria patients.胱氨酸尿症（Cystinuria）是一类胱氨酸转运相关的遗传性疾病，占所有肾石症病例的1%~2%。其临床与病理特征为尿液中胱氨酸过度排泄以及复发性胱氨酸肾石症。肾小管上皮细胞对胱氨酸的转运缺陷，源于转运异二聚体的突变：该异二聚体包含通过共价二硫键连接的b0,+AT蛋白（由SLC7A9基因编码）与rBAT蛋白（由SLC3A1基因编码）。本研究借助CRISPR-Cas9系统（Clustered Regularly Interspaced Short Palindromic Repeats-associated protein 9），通过人工敲除Slc7a9基因第3外显子的7bp片段，成功构建了新型B型胱氨酸尿症大鼠模型。经验证，该Slc7a9基因敲除大鼠在基因组、转录组、翻译水平与生物学表型上均与人类胱氨酸尿症特征高度相似，同时还出现了髓质纤维化等典型继发性病变。基于该新型胱氨酸尿症大鼠模型，本研究构建了首个B型胱氨酸尿症转录组数据库。通过对差异表达基因（DEGs, Differentially Expressed Genes）进行功能注释，本研究提出了谷胱甘肽代谢通路在该模型大鼠肾脏中的潜在调控作用；KEGG（Kyoto Encyclopedia of Genes and Genomes）富集分析结果显示，Slc7a9基因敲除诱导了诸多此前尚未被研究的生物学变化。本研究构建的该大鼠模型及其转录组数据库，可模拟人类B型胱氨酸尿症的发病机制与临床结局，旨在深入阐明胱氨酸尿症的病理生理机制，可为探寻减轻胱氨酸尿症患者肾损伤的全新靶点与干预策略提供参考依据。