Characterization of the gene and promoter for RTI40, a differentiation marker of type I alveolar epithelial cells.
In an effort to understand the processes that establish and maintain the differentiated state of the alveolar epithelium, we have analyzed the gene for rat type I cell 40 kD protein (RTI40), an apical integral plasma membrane protein expressed in type I but not type II alveolar epithelial cells. The RTI40 gene spans 35 kilobase pairs; it contains 6 exons and at least 6 rat Identifier repetitive elements. Three exons encode the predicted RTI40 extracellular domain and one encodes the single transmembrane spanning domain. The final exon encodes one amino acid followed by a stop codon. RTI40 gene transcription starts downstream from a TATA homology, which is immediately adjacent to putative binding sites for thyroid transcription factor 1 and Sp1. In H441 cell transfections, mutagenesis of a 5'-flanking fragment (-2496 to +104) revealed two regions that contribute to promoter activity: -1247 through -795 and -163 through -81. Heterologous promoter fusion experiments suggest that a cooperative interaction between these regions activates transcription. In transfected type II cells, deletion across the proximal region produced a 6-fold drop in promoter activity, whereas deletion across the distal region was without apparent effect. These results provide a foundation to analyze further the factors that govern alveolar epithelial cell phenotype.
Cardiovascular Research Institute, and Departments of Medicine and Pediatrics, University of California San Francisco, California, USA. vanderbi@itsa.ucsf.edu
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JN
Vanderbilt
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LG
Dobbs
D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D015415:Biomarkers; D002454:Cell Differentiation / Q000502:physiology; D004847:Epithelial Cells / Q000737:chemistry / Q000166:cytology*; D005091:Exons / Q000235:genetics; D017353:Gene Deletion; D017930:Genes, Reporter; D008156:Luciferases / Q000235:genetics; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000502:physiology*; D011506:Proteins / Q000032:analysis / Q000235:genetics*; D011650:Pulmonary Alveoli / Q000166:cytology*; D051381:Rats; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D000098853:Podoplanin
D020121:5' Untranslated Regions; D015415:Biomarkers; D008156:Luciferases; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011506:Proteins; C092025:Pdpn protein, rat; D000098853:Podoplanin