ESTROGEN-TREATMENT INDUCES ELEVATED EXPRESSION OF HMG1 IN MCF-7 CELLS

The high mobility group (HMG)1 protein is a highly conserved and ubiqu itous chromosomal protein found enriched in active chromatin, In this study, we have investigated the effect of estrogen on the expression o f the human high mobility group protein HMG1 gene and found that the H MG1 mRNA level in MCF-7 cells was sharply increased 2.5-fold after 30 min of estrogen treatment. Under continuous estrogen treatment, the HM G1 mRNA level decreased to a 1.5 times that of the basal level at 90 m in and remained at this elevated level under estrogen treatment for up to 24 h. These results support the recent finding by Verrier et al, ( C. S. Verrier, 1997, Mel. Endocrinol, 11, 1009-1019) that HMG1 promote s the binding of the estrogen receptor to the estrogen response elemen t and further reinforce our believe that HMG1 plays a significant role in estrogen-induced gene expression. (C) 1998 Academic Press.