International Mammalian Genome Society

The 15th International Mouse Genome Conference (2001)

Table of Contents * Complex Genetics * Developmental Genetics * Gene Annotation * Gene Discovery * Genome Sequencing * Functional Genomics * Mutagenesis * Presentations * Verne Chapman Memorial Lecture

A DEFECT IN A NOVEL NEK-FAMILY KINASE CAUSES CYSTIC DISEASE IN THE MOUSE AND IN ZEBRAFISH

David Beier
Brigham & Women's Hospital/Harvard Medical School
20 Shattuck Street
Boston, MA 02115 USA

Co-Authors: 1)Liu S, 1)Lu W, 1)Kuida S, 2)Obara-Ishihara T, 2)Drummond I
Institutions: 1)Genetics Division, Brigham and Women's Hospital, Harvard Medical School, 2)Renal Division, Massachussetts General Hospital

The juvenile cystic kidney (jck) mutation results in progressive polycystic kidney disease. By positional cloning we identified a mutation in a novel Nek kinase protein, which we call Nek8. The mutation results in a gly-to-val substitution in a highly conserved amino acid motif. To prove that this defect causes cystic disease, we performed a cross-species analysis taking advantage of the evidence that morpholino anti-sense oligos can be used to abrogate gene function in developing zebrafish. Treatment of embryos with an oligo corresponding to the 5' end of the zebrafish ortholog of Nek8 resulted in the formation of pronephric cysts. In vitro studies reveal that expression of either jck mutant Nek8 gene or a construct mutated in the kinase domain results in markedly enlarged and multinucleated cells, which also demonstrate a striking loss of actin stress fibers. Mutant jck kidneys do not show multinucleation in vivo and immunohistochemical analysis does not show mislocalization of membrane proteins. However, EM analysis reveals that, prior to cyst formation, the collecting duct epithelia appears to be lifting off the basement membrane.We suggest that a disruption in actin cytoskeletal assembly by the jck mutation affects cellular adhesion functions, which results in the development of cysts. Further, we suggest that a comparative analysis of gene function in different model systems represents a powerful means to annotate gene function.