Endothelial signaling in kidney morphogenesis: a role for hemodynamic forces

Area of Science:

• Developmental Biology
• Renal Physiology
• Vascular Biology

Background:

• Endothelial cells are crucial for embryonic organ development, but the signaling pathways remain unclear.
• Glomerulogenesis, the formation of the kidney's filtering units, depends on vascularization.

Purpose of the Study:

• To investigate the role of vascular signals in embryonic kidney development, specifically glomerulogenesis.
• To identify the molecular mechanisms linking vascular presence to glomerular assembly.

Main Methods:

• Utilized zebrafish mutants with defects in glomerulogenesis and cardiac function.
• Employed pharmacological inhibition of cardiac output and laser-induced vascular occlusion.
• Assessed the expression and regulation of matrix metalloproteinase-2 (MMP-2) in renal endothelial cells.
• Investigated the effect of MMP-2 inhibition using TIMP-2.

Main Results:

• Mutations disrupting glomerulogenesis also caused cardiac dysfunction, highlighting a link between circulation and kidney development.
• Absence of blood flow, induced by various methods, prevented glomerular formation.
• Renal endothelial cell expression of MMP-2 was regulated by blood flow, suggesting a flow-sensitive signaling pathway.
• Inhibition of MMP-2 activity blocked glomerulogenesis without affecting blood circulation.

Conclusions:

• Vascular blood flow is a critical requirement for proper glomerular assembly during embryonic development.
• A stretch-responsive signaling pathway involving MMP-2 in endothelial cells likely mediates the effects of blood flow on glomerulogenesis.