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J. Virol., Feb 1997, 965-970, Vol 71, No. 2
SY Choi, K van de Mark and DV Faller
The infection of cells with Moloney murine leukemia virus (M-MuLV) causes
an increase in specific cellular gene products, including the major
histocompatibility complex (MHC) class I antigens. This upregulation occurs
through a transactivation process mediated by the long terminal repeat
(LTR) of M-MuLV, and we show here that the gene activation response to the
LTR requires at least one specific cis element within the MHC proximal
promoter region. Nested deletions of MHC class I H-2Kb gene promoter
sequence were subcloned into a chloramphenicol acetyltransferase (CAT)
reporter vector and then transiently introduced into BALB/c-3T3 cells
expressing M-MuLV or cotransfected into BALB/c-3T3 cells with a vector
containing subgenomic portions of the virus, including the LTR. CAT
activity assays demonstrated that a minimal H-2Kb gene promoter (-64 to
+12) contained elements sufficient for this transactivation. DNase I
footprinting assays located a protein-binding site in the region of -64 to
-34 bp from the transcriptional start site, and point mutation analysis
confirmed the location of this cis-acting element, designated the let
response element (LRE), and defined a binding motif. This LRE is distinct
from binding sites for currently known transcription factors in the class I
MHC gene promoter and is conserved in the promoters of human and murine MHC
class I genes. Mutation of the LRE resulted in dramatic reduction in both
DNA-protein binding activity in electrophoretic mobility shift assay and in
the ability of the mutated promoter to respond to retroviral
transactivation. Addition of the LRE to a heterologous promoter conferred
the ability to respond to retroviral transactivation.
Copyright © 1997, American Society for Microbiology
Identification of a cis-acting element in the class I major histocompatibility complex gene promoter responsive to activation by retroviral sequences
Cancer Research Center, Department of Medicine, Boston University School of Medicine, Massachusetts 02118, USA.
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