Identification and functional characterization of NODAL rare variants in heterotaxy and isolated cardiovascular malformations.
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.
Mohapatra
Bhagyalaxmi
B
Department of Pediatrics (Cardiology), Baylor College of Medicine, Houston, TX 77030, USA.
Casey
Brett
B
Li
Hua
H
Ho-Dawson
Trang
T
Smith
Liana
L
Fernbach
Susan D
SD
Molinari
Laura
L
Niesh
Stephen R
SR
Jefferies
John Lynn
JL
Craigen
William J
WJ
Towbin
Jeffrey A
JA
Belmont
John W
JW
Ware
Stephanie M
SM
D000595:Amino Acid Sequence; D001483:Base Sequence; D019521:Body Patterning; D018376:Cardiovascular Abnormalities / Q000235:genetics* / Q000378:metabolism; D002648:Child; D015331:Cohort Studies; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D055457:Nodal Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism
C526007:NODAL protein, human; D055457:Nodal Protein; C497782:SMAD2 protein, human; C497790:SMAD3 protein, human; D051899:Smad2 Protein; D051900:Smad3 Protein