Species differences in cis-elements of the Pro alpha 1(I) procollagen promoter and their binding proteins

Previous studies suggest that there may be species differences in the utili zation of cis-elements of the type I collagen genes. The present study was designed to examine this possibility by focusing on two regions of the pro alpha 1(I) collagen promoter. One is the GC-rich A1 region (-194/168) that modulates transcriptional activity or the mouse promoter. The other contain s a glucocorticoid response element (GRE) implicated in negative glucocorti coid regulation of the rat promoter. Unlike mouse A1 probes, probes represe nting the analogous human (-195/-168) and rat (-193/-179) regions failed to bind nuclear proteins in gel shift assays. Binding assays with mouse A1 pr obes containing base substitutions indicated that this behavior could be as cribed to five bases in the human, and two in the rat sequences. In additio n, the pattern of expression of c-Krox, a protein that alters transcription al activity via the mouse A1 clement, differed in mouse and human tissues. Computer analysis revealed differences in the arrangement of CRE half-sites in human and rat pro alpha 1(I) collagen promoters. in a region of the hum an promoter (-700/673) analogous to the rat (-672/-633), there are three ha lf-sites, each separated by two nucleotides, that cooperate in binding of g lucocorticoid receptor. There also is a proximal half site at position -335 of the human promoter that binds glucocorticoid receptor, but it is not pr esent in the rat promoter. This study has defined several species-specific differences in the sequences and nuclear protein binding activity of region s involved in transcriptional activity of the pro alpha 1(I) collagen promo ter. The results suggest that the A1 regions of the human and rat promoters examined here are unlikely to function as regulatory cis-elements, and the y provide a framework for investigating the role of GREs in transcriptional regulation. They also suggest that species differences in cis-elements and transcription factors should be taken into consideration when using hetero logous systems to study collagen gene regulation. J. Cell. Biochem. 73:408- 422, 1999. Published 1999 Wiley-Liss, Inc.dagger