Distinct rat proteins can recognize CCAAT-homologous sequences of the metallothionein promoter and trans-activate this promoter

Oncogene
L P Aniskovitch, S T Jacob

Abstract

We have previously purified and characterized a rat liver protein C'BP-1 that is either identical or closely related to C/EBPdelta (Aniskovitch and Jacob, 1997). The mouse metallothionein-I (MT-I) promoter contains two C'BP-1 binding sites, one of which includes the MRE-c' region (-135 to -110). The C'BP-1 binding activity was detected by EMSA as a major activity for MRE-c' in nonproliferating adult liver cells but not in rat hepatoma cells. In this study, we purified and characterized a factor, C'BP-2, which had a dominant binding activity for MRE-c' in Morris hepatoma 3924A, a poorly differentiated, fast-growing tissue. C'BP-2 is a 28 kDa protein which exists in solution as a monomer. As observed for C'BP-1, affinity-purified C'BP-2 stimulated transcription from the mMT-I gene promoter. DNase I footprinting revealed two C'BP-2 binding sites in the regions that overlap with the CCAAT homologies of the C'BP-1 binding sites on the mMT-I promoter. C'BP-2 made essential contacts with the CCAAT homology and in the region upstream of this sequence. Competition electrophoretic mobility shift assay and methylation interference analysis revealed that C'BP-2 is a protein closely related, but not identical, to CP2. These data suggest tha...Continue Reading

Citations

Dec 4, 2003·Mutation Research·Farzana HaqJames Koropatnick
Sep 2, 1998·Proceedings of the National Academy of Sciences of the United States of America·K GhoshalS T Jacob
Aug 24, 2004·Medical & Biological Engineering & Computing·H J Hermens, M M R Vollenbroek-Hutten

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