Identification and functional characterization of NODAL rare variants in heterotaxy and isolated cardiovascular malformations

Hum Mol Genet. 2009 Mar 1;18(5):861-71. doi: 10.1093/hmg/ddn411. Epub 2008 Dec 8.

Abstract

NODAL and its signaling pathway are known to play a key role in specification and patterning of vertebrate embryos. Mutations in several genes encoding components of the NODAL signaling pathway have previously been implicated in the pathogenesis of human left-right (LR) patterning defects. Therefore, NODAL, a member of TGF-beta superfamily of developmental regulators, is a strong candidate to be functionally involved in congenital LR axis patterning defects or heterotaxy. Here we have investigated whether variants in NODAL are present in patients with heterotaxy and/or isolated cardiovascular malformations (CVM) thought to be caused by abnormal heart tube looping. Analysis of a large cohort of cases (n = 269) affected with either classic heterotaxy or looping CVM revealed four different missense variants, one in-frame insertion/deletion and two conserved splice site variants in 14 unrelated subjects (14/269, 5.2%). Although similar with regard to other associated defects, individuals with the NODAL mutations had a significantly higher occurrence of pulmonary valve atresia (P = 0.001) compared with cases without a detectable NODAL mutation. Functional analyses demonstrate that the missense variant forms of NODAL exhibit significant impairment of signaling as measured by decreased Cripto (TDGF-1) co-receptor-mediated activation of artificial reporters. Expression of these NODAL proteins also led to reduced induction of Smad2 phosphorylation and impaired Smad2 nuclear import. Taken together, these results support a role for mutations and rare deleterious variants in NODAL as a cause for sporadic human LR patterning defects.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Body Patterning
  • Cardiovascular Abnormalities / genetics*
  • Cardiovascular Abnormalities / metabolism
  • Child
  • Cohort Studies
  • Female
  • Genetic Variation
  • Humans
  • Male
  • Molecular Sequence Data
  • Mutation
  • Nodal Protein / chemistry
  • Nodal Protein / genetics*
  • Nodal Protein / metabolism*
  • Sequence Alignment
  • Signal Transduction
  • Smad2 Protein / genetics
  • Smad2 Protein / metabolism
  • Smad3 Protein / genetics
  • Smad3 Protein / metabolism

Substances

  • NODAL protein, human
  • Nodal Protein
  • SMAD2 protein, human
  • SMAD3 protein, human
  • Smad2 Protein
  • Smad3 Protein