Semaphorin3a disrupts podocyte foot processes causing acute proteinuria.

Area of Science:

• Nephrology
• Molecular Biology
• Cell Biology

Background:

• Semaphorin3a (Sema3a) is a secreted protein known to repel migrating axons and endothelial cells.
• In the adult mouse kidney, Sema3a is expressed in podocytes and collecting tubules, suggesting a potential role in renal function.

Purpose of the Study:

• To investigate the effects of exogenous Semaphorin3a on kidney structure and function.
• To explore the potential role of Semaphorin3a in glomerular filtration barrier homeostasis.
• To determine if Vascular Endothelial Growth Factor-A (VEGF-A) can counteract Sema3a-induced kidney damage.

Main Methods:

• Administration of exogenous Semaphorin3a to adult mice.
• Assessment of proteinuria and renal ultrastructure.
• Evaluation of vascular endothelial growth factor-A receptor expression.
• Analysis of slit-diaphragm protein levels (podocin, nephrin, CD2AP).
• Co-administration of Semaphorin3a and VEGF-165.

Main Results:

• Exogenous Semaphorin3a induced acute nephrotic range proteinuria.
• Renal ultrastructural abnormalities included podocyte foot process effacement/fusion and endothelial cell damage.
• Sema3a treatment decreased VEGF receptor expression and downregulated key slit-diaphragm proteins.
• Co-administration with VEGF-165 prevented proteinuria and ultrastructural damage.
• These findings suggest Sema3a's effects are partly mediated by downregulation of VEGF receptor 2 signaling.

Conclusions:

• Semaphorin3a plays a significant role in disrupting glomerular filtration barrier homeostasis.
• The balance between Semaphorin3a and VEGF-A signaling is critical for maintaining kidney health.
• Targeting Sema3a or modulating VEGF-A signaling may offer therapeutic strategies for proteinuric kidney diseases.