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Allelic polymorphism in transcriptional regulatory regions of HLA-DQB genes.

ABSTRACT: Class II genes of the human major histocompatibility complex (MHC) are highly polymorphic. Allelic variation of structural genes provides diversity in immune cell interactions, contributing to the formation of the T cell repertoire and to susceptibility to certain autoimmune diseases. We now report that allelic polymorphism also exists in the promoter and upstream regulatory regions (URR) of human histocompatibility leukocyte antigen (HLA) class II genes. Nucleotide sequencing of these regulatory regions of seven alleles of the DQB locus reveals a number of allele-specific polymorphisms, some of which lie in functionally critical consensus regions thought to be highly conserved in class II promoters. These sequence differences also correspond to allelic differences in binding of nuclear proteins to the URR. Fragments of the URR of two DQB alleles were analyzed for binding to nuclear proteins extracted from human B lymphoblastoid cell lines (B-LCL). Gel retardation assays showed substantially different banding patterns to the two promoters, including prominent variation in nuclear protein binding to the partially conserved X box regions and a novel upstream polymorphic sequence element. Comparison of these two polymorphic alleles in a transient expression system demonstrated a marked difference in their promoter strengths determined by relative abilities to initiate transcription of the chloramphenicol acetyltransferase reporter gene in human B-LCL. Shuttling of URR sequences between alleles showed that functional variation corresponded to both the X box and upstream sequence polymorphic sites. These findings identify an important source of MHC class II diversity, and suggest the possibility that such regulatory region polymorphisms may confer allelic differences in expression, inducibility, and/or tissue specificity of class II molecules.

SUBMITTER: Andersen LC

PROVIDER: S-EPMC2118753 | biostudies-other | 1991 Jan

REPOSITORIES: biostudies-other

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Allelic polymorphism in transcriptional regulatory regions of HLA-DQB genes.

Andersen L C LC Beaty J S JS Nettles J W JW Seyfried C E CE Nepom G T GT Nepoom B S BS

The Journal of experimental medicine 19910101 1

Class II genes of the human major histocompatibility complex (MHC) are highly polymorphic. Allelic variation of structural genes provides diversity in immune cell interactions, contributing to the formation of the T cell repertoire and to susceptibility to certain autoimmune diseases. We now report that allelic polymorphism also exists in the promoter and upstream regulatory regions (URR) of human histocompatibility leukocyte antigen (HLA) class II genes. Nucleotide sequencing of these regulator ...[more]

PMID: 1985121

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Project description:CC chemokine ligand 2 (CCL2) is the most potent monocyte chemoattractant and inter-individual differences in its expression level have been associated with genetic variants mapping to the cis-regulatory regions of the gene. An A to G polymorphism in the CCL2 enhancer region at position -2578 (rs1024611; A>G), was found in most studies to be associated with higher serum CCL2 levels and increased susceptibility to a variety of diseases such as HIV-1 associated neurological disorders, tuberculosis, and atherosclerosis. However, the precise mechanism by which rs1024611influences CCL2 expression is not known. To address this knowledge gap, we tested the hypothesis that rs1024611G polymorphism is associated with allelic expression imbalance (AEI) of CCL2. We used haplotype analysis and identified a transcribed SNP in the 3'UTR (rs13900; C>T) can serve as a proxy for the rs1024611 and demonstrated that the rs1024611G allele displayed a perfect linkage disequilibrium with rs13900T allele. Allele-specific transcript quantification in lipopolysaccharide treated PBMCs obtained from heterozygous donors showed that rs13900T allele were expressed at higher levels when compared to rs13900C allele in all the donors examined suggesting that CCL2 is subjected to AEI and that that the allele containing rs1024611G is preferentially transcribed. We also found that AEI of CCL2 is a stable trait and could be detected in newly synthesized RNA. In contrast to these in vivo findings, in vitro assays with haplotype-specific reporter constructs indicated that the haplotype bearing rs1024611G had a lower or similar transcriptional activity when compared to the haplotype containing rs1024611A. This discordance between the in vivo and in vitro expression studies suggests that the CCL2 regulatory region polymorphisms may be functioning in a complex and context-dependent manner. In summary, our studies provide strong functional evidence and a rational explanation for the phenotypic effects of the CCL2 rs1024611G allele.

Project description:PurposeIn patients with neuroblastoma (NB), treatment with anti-GD2 monoclonal antibody (mAb) directs natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) against tumor cells. However, tumor cytotoxicity is attenuated by ligation of inhibitory killer immunoglobulin-like receptors (KIRs) by HLA class I molecules. KIR3DL1 polymorphism influences its ability to engage HLA-Bw4 ligands. We tested the hypothesis that poorly interacting combinations of KIR3DL1 and HLA ligands are more permissive of mAb-mediated antitumor effect.MethodsKIR3DL1 and HLA-B subtyping were performed with a multiplex intermediate-resolution polymerase chain reaction assay for a cohort of 245 patients who were treated with antibody 3F8 for high-risk NB. Patient outcomes were analyzed according to expected degree of interaction between KIR3DL1 and HLA-B subtypes and grouped as strong, weak, or noninteractors. A comparison of NK response to 3F8 mAb opsonized NB cells between strong- and noninteracting donors was performed by flow cytometry.ResultsKIR3DL1 and HLA-B subtype combinations associated with noninteraction as a result of lack of receptor expression [KIR3DL1(-)], failure of interaction with inhibitory ligands [KIR3DS1(+)], or absence of KIR ligands resulted in significantly improved overall and progression-free survival. Patients with KIR3DL1 and HLA-B subtype combinations that were predictive of weak interaction had superior outcomes compared with those that were predictive of strong interaction; however, both groups were inferior to those with noninteracting subtype combinations. In vitro analysis of 3F8-mediated ADCC showed that KIR3DL1(-) and 3DS1(+) NK cells were insensitive to inhibition by HLA-Bw4-expressing NB targets.ConclusionWe conclude that KIR3LD1 and HLA-B allele combinations can have a prognostic impact on patient survival after treatment with anti-GD2 mAb that relies on NK-ADCC. The survival advantage seen in noninteracting combinations supports the therapeutic disinhibition of individuals with strongly interacting KIR and ligand pairs.

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Allelic polymorphism in transcriptional regulatory regions of HLA-DQB genes.

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Allelic polymorphism in transcriptional regulatory regions of HLA-DQB genes.

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