Glomerular VEGF resistance induced by PKCδ/SHP-1 activation and contribution to diabetic nephropathy

Area of Science:

• Nephrology
• Molecular Biology
• Diabetic Complications

Background:

• Diabetic nephropathy is a major complication of diabetes.
• Glomerular podocytes and vascular endothelial growth factor (VEGF) signaling are crucial for kidney function.
• Dysregulation of protein kinase Cδ (PKCδ) and phosphatases are implicated in diabetic kidney disease.

Purpose of the Study:

• To investigate the role of glucose-induced PKCδ and SHP-1 activation in VEGF signaling.
• To determine the impact of this pathway on podocyte apoptosis and endothelial dysfunction.
• To explore therapeutic targets for diabetic nephropathy.

Main Methods:

• In vitro studies using cultured podocytes.
• In vivo studies using diabetic rodent models (rats and mice).
• Utilized molecular inhibitors, genetic knockout models (PKCδ-knockout mice), and assessed protein expression and signaling pathways.

Main Results:

• High glucose increased PKCδ and p38 MAPK, leading to elevated SHP-1 expression.
• This pathway promoted podocyte apoptosis and inhibited VEGF signaling.
• PKCδ knockout mice showed protection against diabetic kidney injury, reduced albuminuria, and preserved VEGF signaling.
• Inhibitors of PKCδ, p38 MAPK, and SHP-1 negated adverse effects of high glucose.

Conclusions:

• Hyperglycemia-induced PKCδ/p38 MAPK activation and SHP-1 expression contribute to VEGF resistance, podocyte apoptosis, and endothelial dysfunction in diabetic nephropathy.
• This pathway is independent of NF-κB activation.
• Targeting the PKCδ/p38 MAPK/SHP-1 axis offers a potential therapeutic strategy for diabetic kidney disease.