title: HLA-G allelic variants are associated with differences in the HLA-G mRNA isoform profile and HLA-G mRNA levels.
abstract: During pregnancy, the human extra-villous trophoblast in the contact zone between maternal and fetal tissue in the placenta does not express the classical MHC class I and II molecules. Instead, HLA-G and -C, and possibly HLA-E, are expressed. HLA-G may modulate the immunological relationship between mother and fetus in several ways. Finally, the expression of membrane-bound HLA-G and soluble HLA-G has been proposed to influence the outcome of pregnancy, and an aberrant HLA-G expression in pre-eclamptic placentas and spontaneous abortions has been reported. Here, an association between certain HLA-G polymorphisms and the mRNA levels of the different alternatively spliced HLA-G isoforms in first trimester trophoblast cell populations is reported. Several alternatively spliced HLA-G mRNA isoforms, including a 14-bp polymorphism in the 3'UTR end (exon 8) of the HLA-G gene, are expressed at a significantly lower level than the corresponding HLA-G mRNA isoforms with the 14-bp sequence deleted. Furthermore, characteristic HLA-G mRNA isoform expression patterns were associated with specific HLA-G genotypes and alleles. In the HLA-G*01012 and - G*01013 alleles that include the 14-bp sequence, an additional alternative splicing was observed, with the first 92-bp of exon 8 spliced out. This was most pronounced in HLA-G genotypes with G*01013. These findings may have functional implications for the recent reports of aberrant HLA-G expression and reproductive success.
authors.affiliation: Department of Clinical Biochemistry, H:S Hvidovre Hospital, Copenhagen University Hospital, 30 Kettegaard Allé, 2650, Hvidovre, Denmark. hviid@dadlnet.dk
authors.forename: Thomas Vauvert F
authors.initials: TV
authors.lastname: Hviid
authors.forename: Sine
authors.initials: S
authors.lastname: Hylenius
authors.forename: Christina
authors.initials: C
authors.lastname: Rørbye
authors.forename: Lone G
authors.initials: LG
authors.lastname: Nielsen
mesh_terms: D017398:Alternative Splicing; D020869:Gene Expression Profiling; D014644:Genetic Variation; D006680:HLA Antigens / Q000235:genetics*; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014327:Trophoblasts / Q000378:metabolism
chemical_list: D006680:HLA Antigens; D059951:HLA-G Antigens; D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger