CLDN5 as a novel modulator of podocyte adhesion to extracellular matrix via β1-integrin binding

Area of Science:

• Nephrology
• Cell Biology
• Molecular Medicine

Background:

• Podocyte adhesion to the glomerular basement membrane (GBM) is vital for kidney filtration.
• Compromised podocyte integrity is a hallmark of chronic kidney diseases.
• The role of claudins beyond cell-cell junctions in podocyte function is largely unknown.

Purpose of the Study:

• To investigate the role of Claudin-5 (CLDN5) in regulating podocyte adhesion and integrity.
• To elucidate the molecular mechanisms by which CLDN5 influences podocyte-GBM interactions.
• To assess the impact of CLDN5 deficiency on kidney injury in vivo.

Main Methods:

• Super-resolution imaging to determine CLDN5 localization at the podocyte-GBM interface.
• In vitro studies using podocytes to assess adhesion, spreading, and mechanical stress resistance upon CLDN5 deletion.
• Co-immunoprecipitation and Western blotting to analyze CLDN5-beta1-integrin complex formation and beta1-integrin stability.
• In vivo studies using Cldn5-knockout (KO) mice subjected to hypertensive and adriamycin-induced kidney injury models.

Main Results:

• CLDN5 localizes at the podocyte-GBM interface, colocalizing with beta1-integrin.
• CLDN5 deletion in podocytes significantly impairs cell adhesion, spreading, and resistance to mechanical stress.
• CLDN5 forms a stable complex with beta1-integrin, preventing its ubiquitination and degradation by stabilizing its membrane localization.
• Cldn5-KO mice exhibit exacerbated renal injury in response to hypertensive and adriamycin-induced stress.

Conclusions:

• CLDN5 plays a critical extra-junctional role in maintaining podocyte adhesion and integrity.
• CLDN5 stabilizes beta1-integrin, crucial for podocyte mechanical resistance and overall kidney function.
• Targeting CLDN5 may offer a novel therapeutic strategy for chronic kidney diseases characterized by podocyte injury.