Podocyte-specific JAK2 overexpression worsens diabetic kidney disease in mice

Area of Science:

• Nephrology
• Molecular Biology
• Diabetology

Background:

• Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling is implicated in diabetic kidney disease (DKD) pathogenesis.
• Increased JAK-STAT gene expression is observed in glomerular cells, including podocytes, in early DKD patients.
• The direct impact of specific JAK or STAT isoform overexpression in glomerular cells on DKD progression remains unclear.

Purpose of the Study:

• To investigate whether overexpression of JAK2 in glomerular podocytes alone can exacerbate diabetic kidney disease.
• To determine the phenotypic alterations resulting from moderate JAK2 increases in podocytes.

Main Methods:

• Overexpression of JAK2 mRNA in glomerular podocytes of 129S6 mice.
• Assessment of kidney function and histology, including albuminuria, mesangial expansion, glomerulosclerosis, fibronectin accumulation, and glomerular basement membrane thickening.
• Evaluation of podocyte density and STAT3-dependent gene expression.
• Treatment with a JAK1/2 inhibitor to assess therapeutic effects.

Main Results:

• A 2-3 fold increase in glomerular JAK2 expression led to significant increases in albuminuria, mesangial expansion, glomerulosclerosis, glomerular fibronectin accumulation, and glomerular basement membrane thickening.
• Diabetic mice with overexpressed JAK2 showed a significant reduction in podocyte density.
• Treatment with a JAK1/2 inhibitor partially reversed key DKD phenotypic changes and normalized STAT3-dependent gene expression.

Conclusions:

• Moderate increases in podocyte JAK2 expression, mirroring levels in early DKD patients, can directly cause progressive diabetic glomerulopathy.
• JAK1/2 inhibition shows promise in retarding the progression of early diabetic kidney disease by targeting these pathways.