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Abstract: PO2479

DNA Methylation in Repeated Low-Dose Repeated Cisplatin-Induced CKD

Session Information

Category: CKD (Non-Dialysis)

  • 2103 CKD (Non-Dialysis): Mechanisms

Authors

  • Hu, Xiaoru, Augusta University, Augusta, Georgia, United States
  • Ma, Zhengwei, Augusta University, Augusta, Georgia, United States
  • Dong, Zheng, Augusta University, Augusta, Georgia, United States
Background

DNA methylation is an epigenetic mechanism that regulates gene expression by adding methyl groups to DNA molecules via DNA methyltransferases (DNMTs). Aberrant DNA methylation changes have been implicated in the pathogenesis of kidney diseases. Recent work indicates that DNA methylation protects against cisplatin-induced acute kidney injury partially through hypomethylation of interferon regulatory factor 8 (Irf8). However, little is known about DNA methylation in chronic kidney problems following cisplatin exposure.

Methods

Mice and HK2 cells were subjected to repeated low-dose cisplatin treatment (RLDC). We analyzed the expression of DNMTs and the methylation marker 5-methyl-cytosine following RLDC. We further conducted representation bisulfite sequencing (RRBS) to analyze the genome-wide DNA methylation changes. To explore the pathogenic role of DNA methylation, we initially tested the effects of 5-aza, a pharmacological DNMT inhibitor. We further established and tested a conditional knockout mouse model in which DNMT3a is specifically ablated from kidney proximal tubules (PT-DNMT3a-KO).

Results

RLDC induced notable increases in DNMT1 and DNMT3a (but not DNMT3b) expression, which were accompanied by an overall increase in DNA methylation as shown by 5-methyl-cytosine staining. Genome-wide DNA methylation assay identified differentially methylated regions (DMRs) in 171 genes after RLDC. Five of these genes (Oxgr1, Smim22, Sec61a2, lhx1, Nsd1) had hypermethylation in their promoter regions, which was associated with decreased mRNA expression, suggesting the regulation of these genes by DNA methylation. Functionally, 5-aza reduced the expression of fibrosis-related proteins in cisplatin-treated HK2 cells including collagen I and CTGF. In vivo, 5-aza and ablation of proximal tubule DNMT3a both alleviated the decline of renal function, kidney atrophy, and renal fibrosis after repeated cisplatin treatment.

Conclusion

DNMTs are induced in renal tubular cells after cisplatin exposure, accompanied by an overall increase of DNA methylation. Under this condition, DNA methylation contributes to the development of chronic kidney problems. Inhibition of DNMTs may afford therapeutic effects against cisplatin-induced chronic kidney disease.

Funding

  • NIDDK Support