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

• Published in: Human molecular genetics Vol. 18; no. 5; pp. 861 - 871
• Main Authors: Mohapatra, Bhagyalaxmi, Casey, Brett, Li, Hua, Ho-Dawson, Trang, Smith, Liana, Fernbach, Susan D., Molinari, Laura, Niesh, Stephen R., Jefferies, John Lynn, Craigen, William J., Towbin, Jeffrey A., Belmont, John W., Ware, Stephanie M.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.03.2009; Oxford Publishing Limited (England)
• Subjects: Amino Acid Sequence; Base Sequence; Biological and medical sciences; Body Patterning; Cardiovascular Abnormalities - genetics; Cardiovascular Abnormalities - metabolism; Child; Cohort Studies; Female; Fundamental and applied biological sciences. Psychology; Genetic Variation; Genetics of eukaryotes. Biological and molecular evolution; Humans; Male; Molecular and cellular biology; 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; Characterization; Variant; Genetics; Identification; Malformation
• ISSN: 0964-6906; 1460-2083; 1460-2083
• DOI: 10.1093/hmg/ddn411

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-β 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.