CHARACTERIZATION OF PHENOBARBITAL-INDUCIBLE MOUSE CYP2B10 GENE-TRANSCRIPTION IN PRIMARY HEPATOCYTES

The mouse phenobarbital (PB)-inducible Cyp2b10 gene promoter has been isolated and sequenced, and control of its expression has been charact erized, The 1405-base pair (bp) Cyp2b10 promoter sequence is 83% ident ical to the corresponding region from the rat CYP2B2 gene. In addition to the lack of CA repeats, differences include insertion of 42 base p airs (-123/-82 bp) into the middle of a consensus sequence to the so c alled ''Barbie box.'' In this report, we have developed a primary mous e hepatocyte culture system in which endogenous 2B10 mRNA as well as C yp2b10-driven CAT activity were induced by PB and 1,4-bis[2-(3,5-dichl oropyridyloxy)]benzene (TCPOBOP), but not by the 3-chloro derivative o f TCPOBOP, Deletion analysis of the Cyp2b10 promoter identified a basa l transcription element at -64/-34 bp and a negative element at -971/- 775 bp. Sequences contained within the -1404/-971 bp region are respon sible for the induced CAT activity. DNase I protection and gel shift a ssays detected five major protein binding sites within the -1404/-971 bp fragment, one of which shared high sequence identity with a portion of a regulatory element in CYP2B2 gene (Trottier, E,, Belzil, A., Sto ltz, C,, and Anderson, A, (1995) Gene 158, 263-268). Our results indic ate that sequences important for PB-induced transcription of Cyp2b10 g ene are located in the distal promoter.