| Autor: |
Panebra A; Cardiopulmonary Genomics Program, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD 21201-1075, USA., Schwarb MR, Swift SM, Weiss ST, Bleecker ER, Hawkins GA, Liggett SB |
| Jazyk: |
angličtina |
| Zdroj: |
American journal of physiology. Lung cellular and molecular physiology [Am J Physiol Lung Cell Mol Physiol] 2008 Feb; Vol. 294 (2), pp. L190-5. Date of Electronic Publication: 2007 Nov 16. |
| DOI: |
10.1152/ajplung.00277.2007 |
| Abstrakt: |
Beta(2)-adrenergic receptors (beta(2)-AR) expressed on airway epithelial and smooth muscle cells regulate mucociliary clearance and relaxation and are the targets for beta-agonists in the treatment of obstructive lung disease. However, the clinical responses display extensive interindividual variability, which is not adequately explained by genetic variability in the 5'-flanking or coding region of the intronless beta(2)-AR gene. The nonsynonymous coding polymorphism most often associated with a bronchodilator phenotype (Arg16) is found within three haplotypes that differ by the number of Cs (11, 12, or 13) within a 3'-untranslated region (UTR) poly-C tract. To examine potential effects of this variability on receptor expression, BEAS-2B cells were transfected with constructs containing the beta(2)-AR (Arg16) coding sequence followed by its 3'-UTR with the various polymorphic poly-C tracts. beta(2)Arg16-11C had 25% lower mRNA expression and 33% lower beta(2)-AR protein expression compared with the other two haplotypes. Consistent with this lower steady-state expression, beta(2)Arg16-11C mRNA displayed more rapid and extensive degradation after actinomycin D treatment compared with beta(2)Arg16-12C and -13C. However, beta(2)Arg16-12C underwent 50% less downregulation of receptor expression during beta-agonist exposure compared with the other two haplotypes. Thus these haplotypes direct a potential low-response phenotype due to decreased steady-state receptor expression combined with wild-type agonist-promoted downregulation (beta(2)Arg16-11C) and a high-response phenotype due to increased baseline expression combined with decreased agonist-promoted downregulation (beta(2)Arg16-12C). This heterogeneity may contribute to the variability of clinical responses to beta-agonist, and genotyping to identify these 3'-UTR polymorphisms may improve predictive power within the context of beta(2)-AR haplotypes in pharmacogenetic studies. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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