The miscarriage-associated HLA-G -725G allele influences transcription rates in JEG-3 cells.
BACKGROUND
HLA-G is a non-classical HLA with important immunomodulatory roles in pregnancy. A polymorphism in the promoter region, -725G, was previously associated with sporadic miscarriage in women who were unselected with respect to reproductive history. In this study, the transcription levels of different HLA-G promoter haplotypes were examined to determine whether the miscarriage-associated -725G allele influences transcription.


METHODS
Five naturally occurring promoter haplotypes and three variant haplotypes created by site-directed mutagenesis were sub-cloned into luciferase expression vectors and transfected into JEG-3 cells. Expression levels of these eight haplotypes were examined in cultured cells before and after treatment with interferon-beta (IFN-beta), cytosine-5-DNA methyltransferase (M. SssI) and 5-aza-2'-deoxycytidine. Differences in expression levels between haplotypes were determined by analysis of variance (ANOVA).


RESULTS
Promoter haplotypes with the miscarriage-associated -725G allele were expressed at significantly higher levels in all culture conditions compared with otherwise identical haplotypes that had a -725C or -725T allele.


CONCLUSIONS
Variation in the HLA-G promoter region influences transcription rates. Contrary to expectations, increased expression of HLA-G may be disadvantageous in some pregnancies.
Ober
C
C
Department of Human Genetics, The University of Chicago, IL 60637, USA. c-ober@genetics.uchicago.edu
Billstrand
C
C
Kuldanek
S
S
Tan
Z
Z
D000022:Abortion, Spontaneous / Q000235:genetics*; D000483:Alleles; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D015257:DNA-Cytosine Methylases / Q000378:metabolism; D000077209:Decitabine; D005260:Female; D006680:HLA Antigens / Q000235:genetics / Q000502:physiology*; D059951:HLA-G Antigens; D006239:Haplotypes / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000502:physiology*; D006801:Humans; D016899:Interferon-beta / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured
D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D016899:Interferon-beta; D000077209:Decitabine; C081573:DNA modification methylase SssI; D015257:DNA-Cytosine Methylases; D001374:Azacitidine