CELL-SPECIFIC DIFFERENCES IN DNASE-I HYPERSENSITIVITY BETWEEN THE 2 PROMOTERS OF THE RAT GLUCOKINASE GENE

Glucokinase (GK) gene transcription occurs in the liver and the B cell of the endocrine pancreas where it is subject to different modes of r egulation. This is accomplished largely through the use of two linked, cell-specific promoters separated by at least 12 kbp. We have used DN ase I hypersensitivity to explore the chromatin structure surrounding the two promoters in cells that express either the liver or B cell for m of the GK gene, as well as cells that do not express GK. In RIN38 ce lls, a B-cell-derived cell line, hypersensitive sites are detected ove r both the proximal and distal promoters. In liver, hypersensitive sit es are present in the proximal promoter but not the distal promoter. I nterestingly, in H4IIEC3 cells, a hepatoma cell line that has lost the ability to express GK, hypersensitive sites are also found in the pro ximal promoter but not the distal promoter. (C) 1995 Acidemic Press. I nc.