EDNRA variants associate with smooth muscle mRNA levels, cell proliferation rates, and cystic fibrosis pulmonary disease severity.
Airway inflammation and pulmonary disease are heterogeneous phenotypes in cystic fibrosis (CF) patients, even among patients with the same cystic fibrosis transmembrane conductance regulator (CFTR) genotype. Endothelin, a proinflammatory peptide and smooth muscle agonist, is increased in CF airways, potentially contributing to the pulmonary phenotype. Four cohorts of CF patients were screened for variants in endothelin pathway genes to determine whether any of these variants associated with pulmonary function. An initial cohort of 808 CF patients homozygous for the common CF mutation, DeltaF508, showed significant association for polymorphisms in the endothelin receptor A gene, EDNRA (P = 0.04), but not in the related endothelin genes (EDN1, EDN2, EDN3, or EDNRB) or NOS1, NOS2A, or NOS3. Variants within EDNRA were examined in three additional cohorts of CF patients, 238 patients from Seattle, WA, 303 from Ireland and the U.K., and 228 from Cleveland, OH, for a total of 1,577 CF patients. The three additional groups each demonstrated a significant association between EDNRA 3'-untranslated region (UTR) variant rs5335 and pulmonary function (P = 0.002). At the molecular level, single nucleotide primer extension assays suggest that the effect of the variants is quantitative. EDNRA mRNA levels from cultured primary tracheal smooth muscle cells are greater for the allele that appears to be deleterious to lung function than for the protective allele, suggesting a mechanism by which increased receptor function is harmful to the CF airway. Finally, cell proliferation studies using human airway smooth muscle cells demonstrated that cells homozygous for the deleterious allele proliferate at a faster rate than those homozygous for the protective allele.
Darrah
Rebecca
R
Department of Pediatrics, Case Western Reserve University, Cleveland, Ohio 44106, USA.
McKone
Edward
E
O'Connor
Clare
C
Rodgers
Christine
C
Genatossio
Alan
A
McNamara
Sharon
S
Gibson
Ronald
R
Stuart Elborn
J
J
Ennis
Madeleine
M
Gallagher
Charles G
CG
Kalsheker
Noor
N
Aitken
Moira
M
Wiese
Dawn
D
Dunn
John
J
Smith
Paul
P
Pace
Rhonda
R
Londono
Douglas
D
Goddard
Katrina A B
KA
Knowles
Michael R
MR
Drumm
Mitchell L
ML
D000328:Adult; D000483:Alleles; D002460:Cell Line; D049109:Cell Proliferation; D015331:Cohort Studies; D003550:Cystic Fibrosis / Q000235:genetics* / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D005786:Gene Expression Regulation; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009130:Muscle, Smooth / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044022:Receptor, Endothelin A / Q000235:genetics* / Q000378:metabolism; D015203:Reproducibility of Results; D012129:Respiratory Function Tests; D014132:Trachea / Q000473:pathology; D055815:Young Adult
D012333:RNA, Messenger; D044022:Receptor, Endothelin A