Functional methylome analysis of human diabetic kidney disease

Area of Science:

• Nephrology
• Epigenetics
• Molecular Biology

Background:

• Poor metabolic control in diabetes mellitus leads to long-term kidney damage.
• Epigenetic modifications, such as DNA methylation, are implicated as mediators of this lasting impact.
• Limited comprehensive data exists on methylation changes in human diabetic kidney disease (DKD).

Purpose of the Study:

• To investigate widespread DNA methylation changes in human DKD kidney tubule samples.
• To identify specific epigenetic alterations and their correlation with gene expression and kidney function.
• To explore the functional role of methylation changes in the tumor necrosis factor alpha (TNF) locus in DKD.

Main Methods:

• Whole-genome bisulfite sequencing for base-resolution methylome mapping of human DKD tubule samples.
• RNA sequencing to measure associated gene expression.
• dCas9-Tet1 technology to manipulate methylation levels at the TNF locus and assess functional impact.
• Analysis of methylation and gene expression in diabetic mouse models.

Main Results:

• Widespread DNA methylation changes were identified in DKD kidney samples.
• Coordinated changes in DNA methylation and gene expression were observed in immune signaling pathways, notably TNF.
• Decreasing TNF methylation increased TNF transcript levels, confirming its regulatory role.
• Elevated TNF levels in diabetic mice exacerbated kidney disease severity, indicated by increased albuminuria.

Conclusions:

• DKD kidneys exhibit significant, widespread DNA methylation alterations.
• Epigenetic modifications at the TNF locus play a crucial role in DKD pathogenesis.
• Targeting epigenetic changes, like TNF methylation, may offer novel therapeutic strategies for diabetic nephropathy.