We have compared regulation of the
serglycin gene in human
erythroleukemia (HEL) and CHRF 288-11 cells, which have megakaryocytic characteristics, with promyelocytic HL-60 cells. Deletion constructs were prepared from the region -1123/+42 to -20/+42, and putative regulatory sites were mutated. In all three cell lines, the two major regulatory elements for constitutive expression were the (-80)ets site and the
cyclic AMP response element (CRE) half-site at -70. A
protein from HEL and CHRF, but not HL60, nuclear extracts bound to the (-80)ets site. Another
protein from all three cell lines bound to the (-70)CRE.
Phorbol 12-myristate 13-acetate (PMA) and
dibutyryl cyclic AMP (
dbcAMP) increased expression of the reporter in HEL cells 2.5-3- and 4.5-fold, respectively, from all constructs except those with (-70)CRE mutations. PMA virtually eliminated expression of
serglycin mRNA and promoter constructs, but
dbcAMP increased expression in HL-60 cells. The effects of PMA and
dbcAMP on promoter expression correlated with
mRNA expression. The strengths of two
DNase I-hypersensitive sites in the 5'-flanking region and the first intron in all three cells correlated with relative endogenous
serglycin mRNA expression. An additional
DNase I-hypersensitive site in HL60
DNA in the first intron may be related to the high
serglycin expression in HL60 relative to HEL or CHRF cells.