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Kidney Week

Abstract: FR-PO1031

Kank1 Knockout Fish Causes Proteinuria

Session Information

Category: Genetic Diseases of the Kidney

  • 1002 Genetic Diseases of the Kidney: Non-Cystic

Authors

  • Oda, Keiko, Mie University Graduate School of Medicine, Tsu, Japan
  • Katayama, Kan, Mie University Graduate School of Medicine, Tsu, Japan
  • Tanoue, Akiko, Mie University Graduate School of Medicine, Tsu, Japan
  • Ishikawa, Eiji, Mie University Graduate School of Medicine, Tsu, Japan
  • Ito, Masaaki, Mie University Graduate School of Medicine, Tsu, Japan
Background

Kank family consists of Kank1-4 and contains KN motif, coiled-coil domains, and ankyrin-repeats. Kank1 protein is mostly located in the cytoplasm and is thought to play a role in organizing actin cytoskeleton. Recently, Kank1 is reported to be associated with nephrotic syndrome.

Methods

The expression pattern of Kank1 protein was examined in human frozen kidney sections. Since Kank1 is a conserved gene between human and zebrafish, kank1 knockout zebrafish has been used in this study. The mutant kank1 zebrafish line has a C to T point mutation in exon 3 of kank1 gene, which results in a premature stop codon from CAA (Q) to TAA. By utilizing kank1 knockout zebrafish embryos, we examined its phenotype and performed a functional assay by injecting fluorescent-conjugated dextrans.

Results

Kank1 protein was localized in the podocytes and the proximal tubules. Genotyping of zebrafish embryos from kank1 heterozygous parents was performed by polymerase chain reaction method. The phenotype of kank1 knockout embryos at 4 days per fertilization (dpf) was comparable with that of wild-type embryos. The morphology of pronephros in kank1 knockout embryos was also comparable with that in wild-type embryos under Periodic acid–Schiff stain. However, there was an uptake of both 500-kDa fluorescein isothiocyanate and 10-kDa rhodamine dextrans in the proximal tubules of kank1 knockout embryos at 3.5 dpf while there was only an uptake of 10-kDa rhodamine dextran in the those of wild-type embryos.

Conclusion

Knockout of kank1 in zebrafish might be related to the disturbed filtration barrier in the pronephros and support the human data in nephrotic syndrome.