© 2002 American Thoracic Society DOI: 10.1165/rcmb.2002-0014OC Regulation of Human Clara Cell 10 kD Protein Expression by Chicken Ovalbumin Upstream Promoter Transcription Factors (COUP-TFs)Lung Biology Research Programme and Canadian Institutes of Health Research Group in Lung Development, Hospital for Sick Children; Departments of Laboratory Medicine and Pathobiology, Paediatrics and Physiology, The University of Toronto, Toronto, Ontario, Canada; and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas Address correspondence to: Jim Hu, Lung Biology Research Programme, Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1X8 Canada. E-mail: jhu{at}sickkids.on.ca Clara cell 10 kD protein (CC10) is expressed specifically in a portion of nonciliated airway epithelial cells. The molecular mechanisms that determine its high specificity are not clear. Transcription factors implicated in the regulation of CC10 in rodents do not show the same level of cell specificity. We report here that a 3.3 kb human CC10 DNA fragment, containing the 5' flanking region and promoter, directs lacZ reporter expression in a small portion of Clara cells of the airway epithelia of transgenic mice, indicating the requirement of additional regulatory elements for expression. Addition of an intron containing a transcription enhancer from the human cytokeratin 18 gene greatly enhances the level of transgene expression and broadens epithelial specificity. To gain insight into the mechanisms underlying the cell specificity of human CC10 expression, we performed a promoter analysis of the CC10 gene and a yeast one-hybrid screening to identify factors that regulate the promoter. We have found that chicken ovalbumin upstream promoter transcription factors (COUP-TFs) interact with a proximal promoter region and confirmed the interaction by gel-shift assays. Cotransfection analyses with reporter constructs in cultured cells indicated that COUP-TFs inhibit human CC10 expression. These experiments suggest that COUP-TFs may play a pivotal role in cell specificity of the human CC10 gene by inhibiting its expression in nonpermissive cells.
Abbreviations: activation protein-1, AP-1 • 3-amino-1,2,4-triazole, 3-AT • chloramphenical acetyltransferase, CAT • Clara cell secretory protein, CCSP • Clara cell 10 kD protein, CC10 • chicken ovalbumin upstream promoter transcription factors, COUP-TF • Forkhead box A, FoxA • Octamer, Oct • ovalbumin, OVA • secreted alkaline phosphatase, SEAP • Tris-boric acid-EDTA buffer, TBE • thyroid transcription factor, TTF This article has been cited by other articles:
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