The laminin-binding integrins regulate nuclear factor κB-dependent epithelial cell polarity and inflammation

Area of Science:

• Nephrology
• Developmental Biology
• Cell Biology

Background:

• Laminin-binding integrins (α3β1, α6β1, α6β4) are co-expressed in the developing kidney collecting duct.
• Previous studies showed individual deletion of integrin α3 or α6 subunits had mild or no effect on kidney development.

Purpose of the Study:

• To investigate the cooperative role of integrin α3 and α6 subunits in kidney collecting duct development.
• To elucidate the molecular mechanisms underlying the observed phenotypes.

Main Methods:

• Conditional knockout of integrin α3 and α6 subunits in the developing ureteric bud of mice.
• Histological analysis and assessment of kidney function with age.
• Analysis of cytokine secretion, cell characteristics, and signaling pathways (NF-κB, Snail, Slug) in collecting duct epithelial cells.

Main Results:

• Double knockout of α3 and α6 integrins phenocopied the α3 knockout phenotype in the collecting system.
• Aged double knockout mice developed severe kidney inflammation, fibrosis, and failure.
• Integrin α3α6-null cells showed increased pro-inflammatory cytokine secretion, mesenchymal characteristics, and loss of barrier function due to elevated NF-κB activity.

Conclusions:

• Cooperation between laminin-binding integrins α3 and α6 is crucial for kidney collecting duct development and maintenance.
• These integrins regulate epithelial cell polarity and suppress pro-inflammatory cytokine secretion by controlling NF-κB signaling.
• Dysregulation of these integrins can lead to kidney inflammation, fibrosis, and failure.