KANK deficiency leads to podocyte dysfunction and nephrotic syndrome

Area of Science:

• Genetics
• Molecular Biology
• Nephrology

Background:

• Steroid-resistant nephrotic syndrome (SRNS) is a significant cause of progressive kidney disease.
• Monogenic mutations account for 30% of evaluated SRNS cases, highlighting genetic factors.

Purpose of the Study:

• To identify novel genetic causes of nephrotic syndrome.
• To investigate the role of KANK family genes in podocyte function.

Main Methods:

• Homozygosity mapping and whole-exome sequencing were used to identify mutations.
• Functional genetic screens in Drosophila and zebrafish models were performed.
• Protein localization and interaction studies in rat and human podocytes were conducted.

Main Results:

• Recessive mutations in KANK1, KANK2, and KANK4 were identified in individuals with nephrotic syndrome.
• Drosophila KANK homolog (dKank) is essential for nephrocyte function, with knockdown disrupting filtration structures.
• KANK proteins localize to podocytes, and KANK2 interacts with ARHGDIA, a regulator of RHO GTPases.
• Knockdown of KANK2 in zebrafish and human podocytes recapitulated nephrotic syndrome phenotypes and affected RHOA signaling.

Conclusions:

• KANK family genes play evolutionarily conserved roles in maintaining podocyte structure and function.
• Dysregulation of KANK genes and RHO GTPase signaling contributes to nephrotic syndrome pathogenesis.