Both CLIC4 and CLIC5A activate ERM proteins in glomerular endothelium

Area of Science:

• Nephrology
• Cell Biology
• Molecular Biology

Background:

• Chloride intracellular channel 5A (CLIC5A) is highly expressed in renal glomeruli, activating ERM proteins crucial for cell structure.
• CLIC5A deficiency in mice reduces ERM phosphorylation in podocytes but not endothelial cells (EC).
• Glomerular EC also express CLIC4, suggesting a potential compensatory role.

Purpose of the Study:

• To investigate if CLIC4 can compensate for CLIC5A loss in activating ERM proteins in glomerular EC.
• To determine the role of CLIC4 and CLIC5A in maintaining glomerular capillary architecture and function.

Main Methods:

• Analysis of CLIC5-deficient mice to observe CLIC4 expression and ERM phosphorylation.
• In vitro studies using cultured glomerular EC to assess the effects of CLIC4 silencing and re-expression.
• Generation and analysis of mice lacking both CLIC4 and CLIC5.

Main Results:

• CLIC4 is upregulated and colocalizes with ERM proteins in glomerular EC of CLIC5-deficient mice.
• CLIC4 silencing in cultured EC reduces ERM phosphorylation; exogenous CLIC4 or CLIC5A rescues this effect.
• Mice lacking both CLIC4 and CLIC5 show profoundly reduced ERM phosphorylation in glomerular EC.
• Dual CLIC4/CLIC5 deficiency leads to decreased fenestrae density, proteinuria, glomerular cell proliferation, and matrix deposition.

Conclusions:

• CLIC4 stimulates ERM activation and compensates for CLIC5A in glomerular EC.
• CLIC4/CLIC5A-mediated ERM activation is essential for maintaining glomerular capillary architecture.
• Dysregulation of CLIC4/CLIC5A contributes to glomerular pathology and kidney dysfunction.