Mutations in NEK8 link multiple organ dysplasia with altered Hippo signalling and increased c-MYC expression

Hum Mol Genet. 2013 Jun 1;22(11):2177-85. doi: 10.1093/hmg/ddt070. Epub 2013 Feb 14.

Abstract

Mutations affecting the integrity and function of cilia have been identified in various genes over the last decade accounting for a group of diseases called ciliopathies. Ciliopathies display a broad spectrum of phenotypes ranging from mild manifestations to lethal combinations of multiple severe symptoms and most of them share cystic kidneys as a common feature. Our starting point was a consanguineous pedigree with three affected fetuses showing an early embryonic phenotype with enlarged cystic kidneys, liver and pancreas and developmental heart disease. By genome-wide linkage analysis, we mapped the disease locus to chromosome 17q11 and identified a homozygous nonsense mutation in NEK8/NPHP9 that encodes a kinase involved in ciliary dynamics and cell cycle progression. Missense mutations in NEK8/NPHP9 have been identified in juvenile cystic kidney jck mice and in patients suffering from nephronophthisis (NPH), an autosomal-recessive cystic kidney disease. This work confirmed a complete loss of NEK8 expression in the affected fetuses due to nonsense-mediated decay. In cultured fibroblasts derived from these fetuses, the expression of prominent polycystic kidney disease genes (PKD1 and PKD2) was decreased, whereas the oncogene c-MYC was upregulated, providing potential explanations for the observed renal phenotype. We furthermore linked NEK8 with NPHP3, another NPH protein known to cause a very similar phenotype in case of null mutations. Both proteins interact and activate the Hippo effector TAZ. Taken together, our study demonstrates that NEK8 is essential for organ development and that the complete loss of NEK8 perturbs multiple signalling pathways resulting in a severe early embryonic phenotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abnormalities, Multiple / genetics*
  • Abnormalities, Multiple / metabolism*
  • Abnormalities, Multiple / pathology
  • Cell Line
  • Consanguinity
  • Dandy-Walker Syndrome / genetics*
  • Dandy-Walker Syndrome / metabolism*
  • Dandy-Walker Syndrome / pathology
  • Female
  • Fetus / abnormalities
  • Gene Expression Regulation*
  • Gene Frequency
  • Genome-Wide Association Study
  • Genotype
  • Humans
  • Male
  • Mutation*
  • NIMA-Related Kinases
  • Pancreatic Cyst / genetics*
  • Pancreatic Cyst / metabolism*
  • Pancreatic Cyst / pathology
  • Pedigree
  • Polymorphism, Single Nucleotide
  • Protein Binding
  • Protein Kinases / genetics*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins c-myc / genetics*
  • Signal Transduction*
  • TRPP Cation Channels / genetics
  • TRPP Cation Channels / metabolism

Substances

  • Proto-Oncogene Proteins c-myc
  • TRPP Cation Channels
  • polycystic kidney disease 1 protein
  • polycystic kidney disease 2 protein
  • Protein Kinases
  • Hippo protein, human
  • NEK8 protein, human
  • NIMA-Related Kinases
  • Protein-Serine-Threonine Kinases

Supplementary concepts

  • Renal hepatic pancreatic dysplasia Dandy Walker cyst