title: Transcription and weak expression of HLA-DRB6: a gene with anomalies in exon 1 and other regions.
abstract: HLA-DRB6 is one of the human major histocompatibility complex (MHC) genes present in DR1, DR2, and DR10 haplotypes (approximately 26% of individuals). It shows several anomalies in human and non-human primates, including exon 2 stop codons (non-randomly grouped between codons 74 and 94) and a promoter region, and an exon 1 coming from an inserted retrovirus. It has been shown that not only chimpanzee but also human Mhc-DRB6 lack the usual 3' untranslated (UT) polyadenylation signal, and in the present work it was found that the human DRB6 gene coming from an HLA-DR2 haplotype is effectively transcribed after transfection in mouse L cells, and that HLA-DRB6 molecules may be expressed on the cell surface. DRB6 transcription level is remarkably lower in human than in chimpanzee. Moreover, their exons 1 (both taken from the 3'LTR region of a mammary tumor retrovirus) are also different; this shows that these viral insertions may be an important mechanism for different evolutionary changes in orthologous genes of different species. The pathways by which DRB6 molecules may be expressed on the membrane are unclear but other examples of truncated protein expression have also been described, even within the human major histocompatibility complex (i. e., in HLA-G). Finally, the presence of mature HLA-DRB6 mRNA molecules supports the notion that splicing may take place even in the absence of a canonical 3'UT polyadenylation signal.
authors.affiliation: Department of Immunology, Hospital Universitario 12 de Octubre, Universidad Complutense, Carretera de Andalucía, E-28041 Madrid, Spain.
authors.forename: V M
authors.initials: VM
authors.lastname: Fernandez-Soria
authors.forename: P
authors.initials: P
authors.lastname: Morales
authors.forename: M J
authors.initials: MJ
authors.lastname: Castro
authors.forename: B
authors.initials: B
authors.lastname: Suarez
authors.forename: M J
authors.initials: MJ
authors.lastname: Recio
authors.forename: M A
authors.initials: MA
authors.lastname: Moreno
authors.forename: E
authors.initials: E
authors.lastname: Paz-Artal
authors.forename: A
authors.initials: A
authors.lastname: Arnaiz-Villena
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D005091:Exons; D015870:Gene Expression; D006684:HLA-DR Antigens / Q000235:genetics*; D059806:HLA-DR beta-Chains; D006801:Humans; D007739:L Cells; D051379:Mice; D008969:Molecular Sequence Data; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D006684:HLA-DR Antigens; D059806:HLA-DR beta-Chains; C069699:HLA-DRB6 antigen; D012333:RNA, Messenger