Genomic organization and regulation of a human 7-helix transmembrane receptor which is expressed in pulmonary epithelial cells and induced in hypoxia.
The genetic, regulatory, and tissue-specific characterization of G-protein-coupled receptors is substantial since it contributes to the identification of the natural ligand which may influence basic physiological processes and cell function. Here we explored the genomic structure of a human orphan seven-transmembrane receptor which presents the human homologue of a receptor which has been controversially identified as a rat adrenomedullin receptor subtype. Based on the cDNA sequence a 3.4 kb genomic DNA fragment was isolated. Sequencing of the fragment and comparison studies revealed an intron of 544 bp in the 5' untranslated region, followed by a second exon encoding the receptor protein of 404 amino acids. The gene is localized on chromosome 12q. The 5' regulatory region contains several SP1, AP2, and CAAT sites as well as hypoxia responsive elements (HRE) both in the 5' and 3' regulatory region. RT-PCR with intron spanning primers demonstrated mRNA signals in various tissues, especially in lung. Characterizing the histological expression pattern in lung sections by nonisotopic in situ hybridization, a strong signal of receptor mRNA was identified in pulmonary epithelial cells of bronchi and alveoli. Analysis of the two human pulmonary epithelial cell lines, H23 and A549, showed significant mRNA induction of this receptor subtype in hypoxia.
Hänze
Jörg
J
Department of Internal Medicine, Justus-Liebig-University, Klinikstrasse 36, D-35392 Giessen, Germany. joerg.haenze@innere.med.uni-giessen.de
Groneberg
David A
DA
Rose
Frank
F
Hanisch
Anika
A
Dötsch
Jörg
J
Peiser
Christian
C
Seeger
Werner
W
Rascher
Wolfgang
W
Fischer
Axel
A
Grimminger
Friedrich
F
D015687:Cell Hypoxia; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000502:physiology; D005786:Gene Expression Regulation; D015894:Genome, Human; D006801:Humans; D008168:Lung / Q000166:cytology; D011956:Receptors, Cell Surface / Q000235:genetics*; D043562:Receptors, G-Protein-Coupled; D020133:Reverse Transcriptase Polymerase Chain Reaction
D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C450520:seven-transmembrane G-protein-coupled receptor