Alleles of the proximal promoter of BAT1, a putative anti-inflammatory gene adjacent to the TNF cluster, reduce transcription on a disease-associated MHC haplotype.
BACKGROUND
BAT1 belongs to the DEAD-box family of proteins, and is encoded in the central region of the MHC, a region containing genes affecting immunopathological disorders including Type 1 diabetes. We showed that BAT1 can reduce inflammatory cytokine production, supporting its candidacy as a disease gene. Here we examined the proximal promoter region of BAT1.


RESULTS
Ten single nucleotide polymorphisms were identified in approximately 1.4 kb of sequence, defining at least seven alleles. Sections of the BAT1 promoter region were amplified from cells homozygous for the MHC haplotypes associated with susceptibility (HLA-A1, B8, DR3; 8.1 haplotype) and resistance (HLA-A3, B7, DR15; 7.1 haplotype) to diabetes and cloned into a promoter-less luciferase-encoding plasmid. Jurkat cells transiently transfected with fragments from the 8.1 haplotype exhibited a lower luciferase activity than those transfected with fragments from the 7.1 haplotype, indicating reduced transcription. The effect was clearest with the 520 bp immediately upstream of the transcriptional start site. Electrophoretic mobility shift assays using oligonucleotides spanning polymorphic sites within the 520 bp (proximal) promoter fragment showed haplotype-specific binding of nuclear proteins.


CONCLUSIONS
In view of the anti-inflammatory role of BAT1, reduced production on a disease-associated haplotype constitutes a novel and self-consistent model for the effect of central MHC genes on disease.
Wong
Agnes M-L
AM
Department of Pathology, University of Western Australia, Nedlands 6009, Western Australia. ajessiew@cyllene.uwa.edu.au
Allcock
Richard J N
RJ
Cheong
Karey Y M
KY
Christiansen
Frank T
FT
Price
Patricia
P
D000483:Alleles; D001483:Base Sequence; D003001:Cloning, Molecular; D003920:Diabetes Mellitus / Q000235:genetics / Q000276:immunology; D015788:HLA-A1 Antigen / Q000235:genetics / Q000276:immunology; D015795:HLA-B8 Antigen / Q000235:genetics / Q000276:immunology; D015803:HLA-DR3 Antigen / Q000235:genetics / Q000276:immunology; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D019169:Jurkat Cells; D008156:Luciferases / Q000235:genetics; D008285:Major Histocompatibility Complex / Q000235:genetics* / Q000276:immunology; D008969:Molecular Sequence Data; D010957:Plasmids; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D015788:HLA-A1 Antigen; D015795:HLA-B8 Antigen; D015803:HLA-DR3 Antigen; D014409:Tumor Necrosis Factor-alpha; D008156:Luciferases