<i>Dnmt3a</i> and <i>Dnmt3b</i>-Decommissioned Fetal Enhancers are Linked to Kidney Disease.

Abstract

Cytosine methylation is an epigenetic mark that dictates cell fate and response to stimuli. The timing and establishment of methylation logic during kidney development remains unknown. DNA methyltransferase 3a and 3b are the enzymes capable of establishing <i>de novo</i> methylation. We generated mice with genetic deletion of <i>Dnmt3a</i> and <i>Dnmt3b</i> in nephron progenitor cells (<i>Six2</i>^<i>Cre</i><i>Dnmt3a/3b</i>) and kidney tubule cells (<i>Ksp</i>^<i>Cre</i><i>Dnmt3a/3b</i>). We characterized <i>Ksp</i>^<i>Cre</i><i>Dnmt3a/3b</i> mice at baseline and after injury. Unbiased omics profiling, such as whole genome bisulfite sequencing, reduced representation bisulfite sequencing and RNA sequencing were performed on whole-kidney samples and isolated renal tubule cells. <i>Ksp</i>^<i>Cre</i><i>Dnmt3a/3b</i> mice showed no obvious morphologic and functional alterations at baseline. Knockout animals exhibited increased resistance to cisplatin-induced kidney injury, but not to folic acid-induced fibrosis. Whole-genome bisulfite sequencing indicated that <i>Dnmt3a</i> and <i>Dnmt3b</i> play an important role in methylation of gene regulatory regions that act as fetal-specific enhancers in the developing kidney but are decommissioned in the mature kidney. Loss of <i>Dnmt3a</i> and <i>Dnmt3b</i> resulted in failure to silence developmental genes. We also found that fetal-enhancer regions methylated by <i>Dnmt3a</i> and <i>Dnmt3b</i> were enriched for kidney disease genetic risk loci. Methylation patterns of kidneys from patients with CKD showed defects similar to those in mice with <i>Dnmt3a</i> and <i>Dnmt3b</i> deletion. Our results indicate a potential locus-specific convergence of genetic, epigenetic, and developmental elements in kidney disease development.