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Molecular characterization of KIR3DL3
Anita E Trundley1, Susan E Hiby, Chiwen Chang
1Department of Pathology, Tennis Court Road, Cambridge, CB2 1QP, UK.
Immunogenetics
|January 5, 2006
Summary
Killer-cell immunoglobulin-like receptor 3DL3 (KIR3DL3) is a gene encoding a protein not typically expressed in healthy individuals. Its expression in NK cells may be induced in specific conditions.
Area of Science:
- Immunology
- Genetics
- Cell Biology
Background:
- Killer-cell immunoglobulin-like receptors (KIRs) are key regulators of natural killer (NK) cell and T-cell subset activity.
- KIR3DL3 is a centromeric framework gene within the human KIR cluster, present in all haplotypes.
- KIR3DL3 possesses a unique structure with a single inhibitory motif and lacks a stem region found in other KIRs.
Purpose of the Study:
- To investigate the expression of KIR3DL3 in human peripheral blood and decidual NK cells.
- To analyze the methylation status of the KIR3DL3 promoter and its effect on protein expression.
- To characterize the polymorphism of the KIR3DL3 gene.
Main Methods:
- Reverse transcriptase polymerase chain reaction (RT-PCR) for mRNA detection.
- Protein analysis using a KIR3DL3-specific monoclonal antibody (CH21).
- Bisulphite conversion method to assess promoter methylation.
- Quantitative RT-PCR and sequencing for variant analysis.
Main Results:
- KIR3DL3 mRNA was detected in CD56(bright) NK cells from peripheral blood and decidua, and in the NK92 cell line.
- The KIR3DL3 promoter was found to be heavily methylated, inhibiting surface protein expression.
- Demethylation induced detectable surface protein expression.
- Fourteen KIR3DL3 variants were identified in 25 individuals, with substitutions clustering near the transmembrane region.
Conclusions:
- KIR3DL3 is not a pseudogene and encodes a protein.
- Protein expression is suppressed in healthy individuals due to promoter methylation.
- KIR3DL3 expression may be inducible under specific developmental or pathological circumstances.