Retinol-regulated gene expression in human tracheobronchial epithelial cells. Enhanced expression of elongation factor EF-1α

Conducting airway epithelial cells requires vitamin A or its synthetic chemicals (retinoids) for their survival and for the expression of normal mucociliary functions. By using molecular cloning, we have shown that one of the effects of retinol on cultured human tracheobronchial epithelial (HTBE) cells is the enhancement (from 2- to 4-fold) of the mRNA encoding the elongation factor EF-1α. Sequence analysis has shown that clone HT7, which was identified by differential hybridization procedures, contained a cDNA insert which encoded a protein closely resembling (81%) elongation factor EF-1α from brine shrimp and completely identical to the published sequence of human elongation factor EF-1α (Brands, H.H.G.M., Maassen, J. A., Van Hemert, F. J., Amons, R., and Moller, W. (1986) Eur. J. Biochem. 155, 167-171). Regions of homology of HT7 to EF-Tu from yeast mitochondria, plant chloroplasts, and Escherichia coli are also evident. A single RNA band at 1700 bases was observed for both untreated and retinol-treated HTBE cells, and for mouse liver and parotid glands when Northern transfer from denaturing agarose gel was probed with a ³²P-labeled HT7 insert. An enhanced amino acid incorporation and increased protein content per cell for HTBE cells grown in the presence of retinol were observed. Results presented by these studies indicate that retinol may regulate the transcription of a factor required for translation.