The pentanucleotide ATTGG, the "inverted CCAAT," is an essential element for HLA class I gene transcription.
The HLA class I genes, HLA-A, -B, and -C, contain an inverted CCAAT sequence (ATTGG) located 20 bp upstream of the canonical CCAAT and approximately 70 bp upstream of the transcription initiation site. We have investigated the transcriptional function of the class I inverted CCAAT sequence using the HLA-normal cell line, HeLa. Deletion, mutation, or inversion of the inverted CCAAT sequence abrogated or reduced the activity of the class I promoter, as assessed by luciferase reporter gene assays in transient gene expression experiments. This activity coincided with occupancy of the inverted CCAAT motif, as tested by electrophoretic mobility shift assays using the wild-type sequence and mutated variants of the sequence. The ATTGG-binding protein was not CP2, NF-1, or other known CCAAT-binding proteins, but the complex may contain a CP1/NF-Y-like protein. Our results indicate that this inverted CCAAT sequence is an essential element for the expression of HLA class I genes and that its transcriptional activity depends upon the sequence, position, and orientation of the pentanucleotide.
Schoneich
J
J
Immunology Program, Sloan-Kettering Institute for Cancer Research, New York, NY 10021, USA.
Lee
J L
JL
Mansky
P
P
Sheffery
M
M
Yang
S Y
SY
D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000502:physiology; D005805:Genes, MHC Class I; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000502:physiology; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D015395:Histocompatibility Antigens Class I; D009687:Nuclear Proteins