NKG2D splice variants: a reexamination of adaptor molecule associationsRabinovich, Brian; Li, Jennifer; Wolfson, Martin; Lawrence, William; Beers, Courtney; Chalupny, Jan; Hurren, Rose; Greenfield, Brad; Miller, Richard; Cosman, David
doi: 10.1007/s00251-005-0078-xpmid: 16470377
NKG2D is a homodimeric C-type lectin-related receptor expressed on natural killer (NK) cells and T cells. In mice, alternative deoxyribonucleic acid (DNA) splicing generates two isoforms of NKG2D that differ in the length of their cytoplasmic domains. Their ability to induce cellular activation is mediated via association with two membrane-bound, signaling adaptor molecules, DAP10 and DAP12. It has been reported that the long form of NKG2D associates exclusively with DAP10, whereas the short variant can interact with either adaptor. The short isoform was reported to be almost undetectable in naïve NK cells. Using two distinct cell types, we demonstrate that like the short isoform, the long variant of NKG2D also associates not only with DAP10 but also with DAP12. Using reporter cells (70Z/3), we demonstrate that DAP12 can compete equally with DAP10 for association with both variants of NKG2D when DAP10 and DAP12 are coexpressed. Cross-linking either isoform of NKG2D induces a calcium flux when associated exclusively with DAP10 or DAP12. Moreover, using quantitative polymerase chain reaction (PCR), we also show that the short isoform of NKG2D is expressed in naïve NK cells. Our data suggest that signaling via mouse NKG2D isoforms is more complex than originally presented.
Gender-specific associations between MICA-STR and nasopharyngeal carcinoma in a southern Chinese Han populationTian, Wei; Zeng, Xiao-min; Li, Li-xin; Jin, He-kun; Luo, Qi-zhi; Wang, Fan; Guo, Shi-shi; Cao, Ya
doi: 10.1007/s00251-006-0093-6pmid: 16547745
Previous studies have identified several HLA-B specificities that are associated with nasopharyngeal carcinoma (NPC) in populations of Chinese descent, in particular HLA-B35, -B38, -B46, and -B58. Perhaps except for HLA-B46, other associations cannot be simply accounted for by the linkage disequilibrium between HLA-A and B loci. The human major histocompatibility complex (MHC) class I chain-related gene A (MICA) maps 46 kb centromeric to HLA-B and is highly polymorphic; it encodes a stress-inducible protein which functions as a ligand for the NKG2D/DAP10 complex to activate natural killer (NK) cells, γδ T cells, and CD8+ T cells. We postulated MICA gene as a susceptibility factor for nasopharyngeal carcinoma, an Epstein–Barr virus-associated malignancy. In this study, 218 unrelated patients newly diagnosed with NPC and 196 randomly selected healthy controls from southern China mainland were analyzed for the short tandem repeat polymorphism of exon 5 of MICA gene (MICA-STR) and MICA gene deletion, using fluorescent polymerase chain reaction-gene scanning (PCR/size-sequencing) and polymerase chain reaction-sequence-specific priming (PCR/SSP) technology. MICA*A9 was present at significantly increased frequency in the patient group (P
C=0.0001002, OR=2.528, 95% CI=1.636–3.907), whereas the frequency of MICA*A5.1 was significantly decreased (P
C=0.006, OR=0.594, 95% CI=0.437–0.806). Gender-based stratification revealed a significant increase of MICA*A9 frequency (P
C=0.000072, OR=3.255, 95% CI=1.855–5.709) and a significant decrease of MICA*A5.1 frequency (P
C=0.000737, OR=0.486, 95% CI=0.337–0.702) in male patients with NPC (N=166), compared with male normal controls (N=120). A significant interaction between MICA*A9 and gender was observed (
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=41.58, P=0.0001). Statistics also revealed heterogeneity of effects among MICA*A5.1/MICA*A9-bearing phenotypes and a dose-dependent effect of MICA*A5.1 and MICA*A9 on NPC risk in male subgroup. This constitutes the first demonstration of a gender-specific association between MICA-STR polymorphism and NPC, which could largely be attributable to the underlying gender-related mechanisms that modulate MICA gene expression. The results provide strong supporting evidence suggesting that MICA*A9 may be a genetic risk factor for NPC in male individuals in this population. The potential interaction between MICA and other non-HLA host factors and environmental exposures remains to be further studied.
Restrictive and diversifying elements of the anti-myelin/oligodendrocyte glycoprotein antibody response in primate experimental allergic encephalomyelitisBüdingen, H.-Christian; Menge, Til; Hauser, Stephen; Genain, Claude
doi: 10.1007/s00251-006-0100-ypmid: 16528499
Autoantibody responses against conformational epitopes of myelin/oligodendrocyte glycoprotein (MOG) possess myelin destructive potential, as demonstrated in the marmoset model of human multiple sclerosis (MS) and in some rodent models of experimental allergic encephalomyelitis. We have previously characterized monoclonal Fab fragments specific for conformational epitopes of MOG that were derived from a combinatorial antibody library generated from a MOG-immune marmoset. In this paper, we address the molecular heterogeneity of humoral responses against MOG in this outbred model of MS by studying additional antibody clones derived from a genetically unrelated animal. We find that all MOG-specific IgGκ Fab fragments, unrelated to genetic make-up, utilize a restricted set of variable region genes, IGHV1 and IGHV3 for the H chain and IGKV1, IGKV3, and IGKV5 for the L chain. Despite these restricting factors, diversity within these antibody repertoires can be observed, predominantly within the H-chain CDR3 regions. Our findings suggest that only a limited set of Ig genes is necessary to launch a diverse, destructive humoral immune response against a single CNS antigen in primates. These results are the first to contribute to a better understanding of how myelin-directed and potentially destructive autoantibody responses may develop in human MS.
Bovine T cell receptor gamma variable and constant genes: combinatorial usage by circulating γδ T cellsHerzig, Carolyn; Blumerman, Seth; Lefranc, Marie-Paule; Baldwin, Cynthia
doi: 10.1007/s00251-006-0097-2pmid: 16541255
Studies here describe expression and sequence of several new bovine T cell receptor gamma (TRG) genes to yield a total of 11 TRG variable (TRGV) genes (in eight subgroups) and six TRG constant (TRGC) genes. Publicly available genomic sequences were annotated to show their placement. Homologous TRG genes in cattle and sheep were assigned, using four accepted criteria. New genes described here include the bovine TRGC6, TRGV2, and TRGV4, homologues of ovine TRGC4, TRGV2, and TRGV4, respectively. The bovine Vγ7 and BTGV1 clones (previously TRGV4 and TRGV2, respectively) were reassigned to new subgroups TRGV7 and TRGV8, respectively, with approval by the IMGT Nomenclature Committee. Three TRGV subgroups (TRGV5, TRGV6, and TRGV8) were further designated as TRGV5-1 and TRGV5-2, TRGV6-1 and TRGV6-2, and TRGV8-1 and TRGV8-2 because each subgroup is comprised of two mapped genes. The complete sequence of bovine TRGC5 is also reported, for which a limited number of nucleotides was previously available, and shown to be most closely related to ovine TRGC5. Analysis of circulating γδ T cells revealed that rearrangement of TRGV genes with TRGC genes is largely dictated by their proximity within one of the six genomic V-J-C cassettes, with all TRG genes expressed by bovine peripheral blood γδ T cells. Cattle are useful models for γδ T cell biology because they have γδ T cells that respond to isopentenylpyrophosphate (IPP) antigens, while mice do not, and some bovine TRGV genes cluster closely with human genes.
Polymorphism of two very similar MHC class Ib loci in rainbow trout (Oncorhynchus mykiss)Dijkstra, Johannes; Kiryu, Ikunari; Yoshiura, Yasutoshi; Kumánovics, Attila; Kohara, Masakazu; Hayashi, Nobuhiro; Ototake, Mitsuru
doi: 10.1007/s00251-006-0086-5pmid: 16518622
As part of an ongoing elucidation of rainbow trout major histocompatibility complex (MHC) class I, the polymorphism of two MHC class Ib loci was analyzed. These loci, Onmy-UCA and Onmy-UDA, are situated head-to-tail and share more than 89% nucleotide identity in their open reading frames. They share 80% identity with some trout Ia alleles. The deduced amino acid sequences suggest that the UCA and UDA molecules are transported to endosomal compartments and may bind peptides in their binding groove. Our survey revealed seven UCA and eight UDA alleles. Similarity indices overlap when comparing within and between UCA and UDA alleles and some cross-locus motif variation is observed. In most trout both UCA and UDA transcripts were found. However, there probably is functional redundancy, because some trout lacked transcription of one of the two loci. Furthermore, for some UCA and UDA alleles, splicing deficiencies, early stop codons, and upstream start codons were found, which may interfere with efficient protein expression. The present study is the first extensive report on MHC class Ib polymorphism assigned to locus in ectotherm species.
Maternal transfer of complement components C3-1, C3-3, C3-4, C4, C5, C7, Bf, and Df to offspring in rainbow trout (Oncorhynchus mykiss)Løvoll, Marie; Kilvik, Terje; Boshra, Hani; Bøgwald, Jarl; Sunyer, J.; Dalmo, Roy
doi: 10.1007/s00251-006-0096-3pmid: 16550351
Defense mechanisms in developing fish are poorly known but before maturation of lymphoid organs and immunocompetence, innate mechanisms are essential. The complement system represents a major part of innate immunity. Our main objective was to map the presence of complement components early in fish development. Rainbow trout eggs, embryos, and hatchlings were assayed for the onset and duration of C3-1, C3-3, C3-4, C4, C5, C7, factor B, and factor D transcription using real-time reverse transcription-polymerase chain reaction. In general, complement transcript levels increased steadily from day 28 postfertilization to hatch, followed by a decrease during yolk–sac resorption. All the complement proteins studied were found in unfertilized eggs. There was no correlation between the transcript and protein levels throughout the study period. Complement proteins appeared in the liver, kidney, and intestine between day 7 and 35 but not until day 77 in the heart. This study is the first to address the ontogeny of several complement components and represents the first evidence that maternal transfer of complement components, other than C3, occurs in teleost fish.