Characterization of paired Ig-like receptors in rats

Tissue Antigens, 2003

The gene for one of the activating members of the paired Ig-like receptor family, Pira6, was isolated from a genomic library and sequenced. The first of 9 exons in the $8.2 kb Pira6 gene encodes the 5 0 untranslated region, the translation initiation site, and approximately half of the signal sequence. The second exon encodes the rest of the signal sequence, exons 3-8 each encode a single Ig-like extracellular domain, and exon 9 encodes the transmembrane region, cytoplasmic tail and 3 0 UTR with four polyadenylation signals and six mRNA instability sequences. A soluble form of PIR-A6 may be generated by alternative splicing. The exonic sequences account for $42% of the Pira6 gene and $34% for the single inhibitory Pirb gene, thus defining Pira and Pirb as genes with relatively short intronic sequences. Extensive sequence homology was found between Pira6 and Pirb from $2 kb upstream of the ATG initiation site to the beginning of intron 8. The Pir genes appear to be distributed in three regions of the proximal end of chromosome 7 based on the present data and an analysis of currently available mouse genomic sequence databases. One region contains a single Pir gene which is almost identical to Pira6, and the other two contain multiple Pir genes in opposite transcriptional orientations. Potential binding sites for hemopoiesisspecific and ubiquitous transcription factors were identified upstream of the Pira6 transcription start sites that reside within the initiator consensus sequence motif. These results provide important clues to the coordinate regulation observed for PIR-A and PIR-B expression during hematopoiesis.

Tissue Antigens, 2008

The genes encoding the murine paired immunoglobulin-like receptors PIR-A and PIR-B are members of a novel gene family which encode cell-surface receptors bearing immunoreceptor tyrosine-based inhibitory motifs (ITIMs) and their non-inhibitorylabivatory counterparts. PIR-A and PIR-B have highly homologous extracellular domains but distinct transmembrane and cytoplasmic regions. A charged arginine in the transmembrane region of PIR-A suggests its potential association with other transmembrane proteins to form a signal transducing unit. PIR-B, in contrast, has an uncharged transmembrane region and several ITIMs in its cytoplasmic tail. These characteristics suggest that PJR-A and PIR-B which are coordinately expressed by B cells and myeloid cells, serve counter.regulatory roles in humoral and inflammatory responses. In the present study we have determined the genomic structure of the single copy PIR-I3 gene. The gene consists of 15 exons and spans approximately 8 kilobases. The first exon contains the 5' untranslated region, the ATG translation start site, and approximately half of the leader peptide sequence. The remainder of the leader peptide sequence is encoded by exon 2. Exons M! encode the six extracellular immunoglobulin-like domains and exons 9 and 10 code for the extracellular membrane proximal and transmembrane regions. The final five exons (exons 11-15) encode for the ITIM-bearing cytoplasmic tail and the 3' untranslated region. The introdexon boundaries of PIR-B obey the GT-AG rule and are in phase I, with the notable exception of the three boundaries determined for ITIM-containing exons. A microsatellite composed of the trinucleotide repeat AAG in the intron between exons 9 and 10 provides a useful marker for studying population genetics.

Journal of immunology (Baltimore, Md. : 1950), 1998

In this study, we demonstrate potent regulatory function of the murine killer cell inhibitory receptor-like molecules, paired Ig-like receptors (PIRs) or p91, using chimeric receptors expressed on the rat basophilic leukemia cell line RBL-2H3. One of the chimeras, which has the transmembrane and cytoplasmic domain of PIR-B fused to the extracellular portion of type IIB receptor for IgG, was able to inhibit the type I receptor for IgE-mediated degranulation response upon coaggregation. This chimera also suppressed cytoplasmic Ca2+ mobilization in the presence and absence of calcium ion in the extracellular medium. Tyrosine to phenylalanine point mutations at the third and fourth immunoreceptor tyrosine-based inhibitory motif-like sequences of PIR-B attenuated the inhibitory effects on degranulation and on cytoplasmic Ca2+ mobilization, indicating the important role of these tyrosines for the delivery of negative signal. In contrast, the cross-linking of another chimeric receptor comp...

Proceedings of the National Academy of Sciences, 1999

The inhibitory function of PIR-B is mediated via its cytoplasmic immunoreceptor tyrosine-based inhibitory motifs, whereas PIR-A pairs with the Fc receptor common ␥ chain to form an activating receptor complex. In these studies, we observed constitutive tyrosine phosphorylation of PIR-B molecules on macrophages and B lymphocytes, irrespective of the cell activation status. Splenocyte PIR-B molecules were constitutively associated with the SHP-1 protein tyrosine phosphatase and Lyn protein tyrosine kinase. In Lyn-deficient mice, PIR-B tyrosine phosphorylation was greatly reduced. Unexpectedly, tyrosine phosphorylation of PIR-B was not observed in most myeloid and B cell lines but could be induced by ligation of the PIR molecules. Finally, the phosphorylation status of PIR-B was significantly reduced in MHC class I-deficient mice, although not in mice deficient in TAP1 or MHC class II expression. These findings suggest a physiological inhibitory role for PIR-B that is regulated by endogenous MHC class I-like ligands.

Journal of Experimental Medicine, 1999

PIR-A and PIR-B, paired immunoglobulin-like receptors encoded, respectively, by multiple Pira genes and a single Pirb gene in mice, are relatives of the human natural killer (NK) and Fc receptors. Monoclonal and polyclonal antibodies produced against a recombinant PIR protein identified cell surface glycoproteins of ‫ف‬ 85 and ‫ف‬ 120 kD on B cells, granulocytes, and macrophages. A disulfide-linked homodimer associated with the cell surface PIR molecules was identified as the Fc receptor common ␥ (FcR ␥ c) chain. Whereas PIR-B fibroblast transfectants expressed cell surface molecules of ‫ف‬ 120 kD, PIR-A transfectants expressed the ‫ف‬ 85-kD molecules exclusively intracellularly; PIR-A and FcR ␥ c cotransfectants expressed the PIR-A/ FcR ␥ c complex on their cell surface. Correspondingly, PIR-B was normally expressed on the cell surface of splenocytes from FcR ␥ c Ϫ / Ϫ mice whereas PIR-A was not. Cell surface levels of PIR molecules on myeloid and B lineage cells increased with cellular differentiation and activation. Dendritic cells, monocytes/macrophages, and mast cells expressed the PIR molecules in varying levels, but T cells and NK cells did not. These experiments define the coordinate cellular expression of PIR-B, an inhibitory receptor, and PIR-A, an activating receptor; demonstrate the requirement of FcR ␥ c chain association for cell surface PIR-A expression; and suggest that the level of FcR ␥ c chain expression could differentially affect the PIR-A/PIR-B equilibrium in different cell lineages. . PIR expression in FcR␥c-deficient and wild-type mice. Bone marrow cells from FcR␥c-deficient (thick line) and wild type mice (thin line) were stained with 6C1 anti-PIR or control (dotted line) mAb, and the stained cells were analyzed as described in the legend for . Only the wild-type mice control staining is illustrated.

The Journal of Immunology, 2001

Proceedings of the National Academy of Sciences, 1997

An Fc␣ receptor probe of human origin was used to identify novel members of the Ig gene superfamily in mice. Paired Ig-like receptors, named PIR-A and PIR-B, are predicted from sequence analysis of the cDNAs isolated from a mouse splenic library. Both type I transmembrane proteins possess similar ectodomains with six Ig-like loops, but have different transmembrane and cytoplasmic regions. The predicted PIR-A protein has a short cytoplasmic tail and a charged Arg residue in the transmembrane region that, by analogy with the Fc␣R relative, suggests the potential for association with an additional transmembrane protein to form a signal transducing unit. In contrast, the PIR-B protein has an uncharged transmembrane region and a long cytoplasmic tail containing four potential immunoreceptor ty-

Immunogenetics, 2005

In mammals many natural killer (NK) cell receptors, encoded by the leukocyte receptor complex (LRC), regulate the cytotoxic activity of NK cells and provide protection against virus-infected and tumor cells. To investigate the origin of the Ig-like domains encoded by the LRC genes, a subset of C2-type Ig-like domain sequences was compiled from mammals, birds, amphibians, and fish. Phylogenetic analysis of these sequences generated seven monophyletic groups in mammals (MI, MII, and FcI, FcIIa, FcIIb, FcIII, FcIV), two in chicken (CI, CII), four in frog (FI-FIV), and five in zebrafish (ZI-ZV). The analysis of the major groups supported the following order of divergence: ZI [or a common ancestor of ZI and F (a cluster composed of the FcIII and FIII groups)], F, CII (or a common ancestor of CII and MII), MII, and MI-CI. The relationships of the remaining groups were unclear, since the phylogenetic positions of these groups were not supported by high bootstrap values. Two main conclusions can be drawn from this analysis. First, the two groups of mammalian LRC sequences must diverged before the separation of the avian and mammalian lineages. Second, the mammalian LRC sequences are most closely related to the Fc receptor sequences and these two groups diverged before the separation of birds and mammals.

Hiromi Kubagawa, University of Alabama at Birmingham Ching-Cheng Chen, University of Alabama at Birmingham Le Hong Ho, Howard Hughes Medical Institute Toshihide Shimada, University of Alabama at Birmingham Lanier Gartland, Howard Hughes Medical Institute Charles Mashburn, Howard Hughes Medical Institute Takahiro Uehara, University of Alabama at Birmingham Jeffrey V. Ravetch, Rockefeller University Max Cooper, Emory University