p49, a putative HLA class I-specific inhibitory NK receptor belonging to the immunoglobulin superfamily

The killer Ig-like receptors (KIR) are a family of highly related MHC class I receptors that show extreme genetic polymorphism both within the human population and between closely related primate species, suggestive of rapid evolutionary diversification. Most KIR are expressed in a variegated fashion by the NK population, giving rise to an NK repertoire of specificities for MHC class I. We compared the promoter for KIR3DL1, which exhibits variegated gene expression, with that for KIR2DL4, which is expressed by all NK cell clones. Maximum transcriptional activity of each was encoded within ∼270 bp upstream of the translation initiation codon. The KIR2DL4 promoter drove reporter gene expression only in NK cells, while the KIR3DL1 promoter was active in a range of cell types, suggesting that the latter requires other regulatory elements for physiological expression. In NK cells, reporter gene expression driven by the KIR2DL4 promoter was greater than that driven by the KIR3DL1 promoter. DNase I footprinting revealed that transcription factor binding sites differ between the two promoters. The data indicate that while the promoters of these two KIR genes share 67% nucleotide identity, they have evolved distinct properties consistent with different roles in regulating the generation of NK repertoire.

Section: Tissue Specificity Of Promoter Activitymentioning

confidence: 82%

mentioning

confidence: 99%

Different and Divergent Regulation of the KIR2DL4 and KIR3DL1 Promoters

Stewart

Bergen

Trowsdale

2003

“…As with other MHC class I molecules, HLA-G is expressed on the cell surface complexed with ␤ 2 -microglobulin and interacts with a variety of receptors on cells of the innate immune system, including NK cells and monocytes (7)(8)(9)(10)(11). One of the intriguing characteristics of the molecular biology of HLA-G is the expression of an alternatively spliced transcript coding for a truncated, soluble molecule (12,13), now designated HLA-G5.…”

Section: T He Nonclassical Mhc Class I Molecule Hla-g Has Beenmentioning

confidence: 99%

A Soluble Isoform of the Rhesus Monkey Nonclassical MHC Class I Molecule Mamu-AG Is Expressed in the Placenta and the Testis

Ryan¹,

Grendell²,

Geraghty

et al. 2002

The nonclassical MHC class I locus HLA-G is expressed primarily in the placenta, although other sites of expression have been noted in normal and pathological situations. In addition, soluble HLA-G isoforms have been detected in the serum of pregnant and nonpregnant women as well as men. The rhesus monkey placenta expresses a novel nonclassical MHC class I molecule Mamu-AG, which has features remarkably similar to those of HLA-G. We determined that the rhesus placenta expresses Mamu-AG mRNA (Mamu-AG5), retaining intron 4 as previously noted in HLA-G5. Immunostaining experiments with Ab 16G1 against the soluble HLA-G5 intron 4 peptide demonstrated that an immunoreactive protein(s) was present in the syncytiotrophoblasts of the chorionic villi of the rhesus placenta, within villous cytotrophoblasts, and occasionally within cells of the villous stroma. The Mamu-AG5 mRNA was readily detected in rhesus testis (although not in ejaculated sperm). Whereas an Ab against membrane-bound Mamu-AG stained few cells, primarily in the interstitium of the testis, there was consistent immunostaining for Mamu-AG5 in cells within the seminiferous tubules, which was corroborated by localization of Mamu-AG mRNA by in situ hybridization. While primary spermatocytes were negative, Sertoli cells, spermatocytes, and spermatids were consistently positive for 16G1 immunostaining. The specific recognition of the soluble Mamu-AG isoform was confirmed by Western blotting of Mamu-AG5 expressed in heterologous cells. The results demonstrate that a soluble nonclassical MHC class I molecule is expressed in the rhesus monkey placenta and testis, and confirm and extend the unique homology between HLA-G and the rhesus nonclassical molecule Mamu-AG.

“…3). This charged residue has been proposed (22) to mediate a possible interaction with the signal transducer protein DAP12 (23), which might render KIR2DL4 an activatory molecule in some circumstances. The presence of two ITIMs and the absence of charged residues in the transmembrane region point to KIR2DL5 being an inhibitory receptor.…”

Section: Full-length Cdna From Kir2dl51 Reveals An Inhibitory Kir Wimentioning

confidence: 99%

KIR2DL5, a Novel Killer-Cell Receptor with a D0-D2 Configuration of Ig-Like Domains

Vilches

Rajalingam

Uhrberg

et al. 2000

124

Four novel killer-cell Ig-like receptor (KIR) genes were discovered by analysis of genomic DNA from a human donor. One gene, KIR2DL5, is expressed by subpopulations of NK cells and T cells, whereas expression of the other three genes could not be detected. KIR2DL5 has two extracellular Ig-like domains of the D0 and D2 type, a structural configuration that was previously unique to KIR2DL4. Although having a similar structure overall, the KIR2DL4 and KIR2DL5 receptors have distinctive amino acid sequences in the ligand-binding extracellular domains and differ in the transmembrane and cytoplasmic motifs that determine signal transduction. Whereas the KIR2DL4 gene is present on all KIR haplotypes and is expressed by all human NK cells, the KIR2DL5 gene is restricted to the “B” subset of KIR haplotypes and is clonally expressed by NK cells within an individual. Chimpanzee genes for KIR2DL4 and KIR2DL5 have been defined and are very similar in sequence to their human orthologs. The donor in whom KIR2DL5 was first detected bears two variants of it that differ by five nucleotide substitutions in the coding region. Although the substitutions are not predicted to affect gene expression, transcription of only one of the two KIR2DL5 variants could be detected.