REGULATION OF THE VITELLOGENIN GENE B1 PROMOTER AFTER TRANSFER INTO HEPATOCYTES IN PRIMARY CULTURES

The estrogen-dependent and tissue-specific regulation of the Xi Xenopu s laevis vitellogenin gene BI promoter has been studied by lipid-media ted DNA transfer into Xenopus hepatocytes in primary culture. Hepatocy tes achieve an efficient hormonal control of this promoter through a f unctional interaction between the estrogen responsive elements and a p romoter proximal region upstream of the TATA box, which is characteriz ed by a high density of binding sites for the transcription factors CT F/NF-I, C/EBP and HNF3. DNA accessibility to restriction enzymes withi n the chromosomal copy of the vitellogenin gene B1 promoter shows that the estrogen responsive unit and the promoter proximal region are sen sitive to digestion in uninduced and estrogen-induced hepatocytes but not in erythrocyte nuclei. Together, these findings support the notion that chromatin configuration as well as the interplay of promoter ele ments mediate proper hormone-dependent and tissue-specific expression of the B1 vitellogenin gene. (C) 1998 Published by Elsevier Science Ir eland Ltd. All rights reserved.