The context of T-cell receptor gamma chain genes among wild mouse species

We have examined the context of mouse T-cell receptor gamma (Tcr ) chain variable (V ) and constant (C) genes among a panel of geographically isolated species of mice. Our Southern hybridization survey with C reveals that essentially three C genes are found among mouse species extending phylogenetically from inbred mice through the feral species Mus pahari. However, a V DNA probe detects three to nine V restriction fragment bands among the same group of mice. These results suggest that certain feral mice such as M. pahari, M. platythrix, and M. shortridgei have amplified numbers of V genes. Studies of individual mice from these particular species indicate the highly amplified V content is not the result of a catastrophic gene duplication or deletion event. We conclude that certain species of mice maintain increased content of V presumably for increased diversity in a Tcell response.     

Polymorphism of minor histocompatibility genes in wild mice

H-2^b-restricted cytolytic T lymphocytes (CTL) were generated against H-1, H-3, and H-4 antigens and tested against target cells of F₁ hybrids between wild mice and inbred H-2 ^b mice. The congenic strain combinations for the CTL production were such that they tested one allele each at the H-1 and H-4 loci and four alleles at the H-3 locus. Most of the wild mice tested came from Southern Germany, but a few mice came from other European countries and Egypt and Israel. Virtually all wild mice typed as positive with CTL directed against H-3^b and H-4^b antigens; 32% of the F₁ hybrids tested reacted with anti-H-1^cCTL and 9% reacted with anti-H-3^d CTL. The positive results were not caused by cross-reaction with allogeneic H-2 antigens controlled by the major histocompatibility complex (Mhc) genes of the wild mice. At least some of the H-3 and H-4 antigens detected by the CTL in the F₁ hybrid were not identical with antigens of the immunizing strains. These results suggest a relatively low degree of polymorphism of the tested minor H loci in wild mice and further support the notion that minor H loci are unrelated to the Mhc.     

Mapping of Igk-V genes using backcrossed laboratory and wild mice

In the mouse, the genes coding for the Ly-2 antigen, the chain of the T-cell receptor, and the immunoglobulin kappa light chain have been located on chromosome 6. Although a tentative order has been proposed for these genes, very few data have been reported concerning their genetic distance. To address this question, we have produced backcross mice between SJL and MAI (a wild-derived strain belonging to the Mus musculus), since these mice segregate for the Ly-2 and Igk-C proteins and for the Igk-V24, Igk-V21, Igk-V10, Igk-V8, and Igk-V4 genes. Twelve recombinants were obtained from 163 backcross mice studied. Two mice showed a recombination between the (Igk-V24, Igk-V10, Igk-V8, Igk-V4) and the (Ly-2, Igk-C, Igk-V21) groups, and ten mice displayed a recombination between the (Igk-V24, Igk-V10, Igk-V8, Igk-V4) group and the Tcrb-C loci. These data imply the following gene order: Tcrb-C .... (Igk-V24, Igk-V10, Igk-V8, Igk-V4) .... (Igk-V21, Igk-C, Ly-2). They indicate a distance of 6.1 cM between Tcrb-C and (Igk-V24, Igk-V10, Igk-V8, Igk-V4) and 1.2 cM between Igk-V24, Igk-V10, Igk-V8, Igk-V4 and the (Igk-V21, Igk-C, Ly-2) groups.     

Polymorphism and phylogeny of dinucleotide repeats in human T-cell receptor Vb6 genes

The Vb6 subfamily is the largest reported subfamily of human T-cell receptor (Tcr) genes with as many as 14 possible members based on variation in reported DNA sequences. A study of the genomic organization of four distinct Vb6 genes indicated that they contained within their introns theuniterrupted dinucleotide repeat (GT)_n, with n>8. DNA amplification primers and conditions were determined which amplified the intron of these four different Vb6 gene segments. All four Vb6 genes tested showed length polymorphism when examined in a group of unrelated individuals. Careful sizing and DNA sequencing showed that the alleles of each gene differed in size by multiples of two base pairs (bp), due to different repeat numbers of the dinucleotide (GT)_n. These four microsatellite polymorphisms had from three to ten alleles, and individual heterozygosities of 26% to 83%. The large number of alleles and the high heterozygosity make these polymerase chain reaction (PCR)-based polymorphisms very attractive genetic markers for segregation studies which postulate the presence of autoimmune susceptibility genes within the Tcrb region. Vb6 hybridization to genomic DNA confirmed the relatively large size of the Vb6 subfamily in several hominoid species. Nucleotide sequencing of an intron of the Vb6 genes from other primates revealed the presence of dinucleotide repeats similar to those found in human Vb6 genes. Thus, the (GT)_n microsatellite was not only present in the Vb6 intron before Vb6 gene duplication, but was present before speciation of the hominoids.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers L07638, L07640, and X07641.     

Diverse wild mouse origins of xenotropic, mink cell focus-forming, and two types of ecotropic proviral genes

We analyzed wild mouse DNAs for the number and type of proviral genes related to the env sequences of various murine leukemia viruses (MuLVs). Only Mus species closely related to laboratory mice carried these retroviral sequences, and the different subclasses of viral env genes tended to be restricted to specific taxonomic groups. Only Mus musculus molossinus carried proviral genes which cross-reacted with the inbred mouse ecotropic MuLV env gene. The ecotropic viral env sequence associated with the Fv-4 resistance gene was found in the Asian mice M. musculus molossinus and Mus musculus castaneus and in California mice from Lake Casitas (LC). Both M. musculus castaneus and LC mice carried many additional Fv-4 env-related proviruses, two of which are common to both mouse populations, which suggests that these mice share a recent common ancestry. Xenotropic and mink cell focus-forming (MCF) virus env sequences were more widely dispersed in wild mice than the ecotropic viral env genes, which suggests that nonecotropic MuLVs were integrated into the Mus germ line at an earlier date. Xenotropic MuLVs represented the major component of MuLV env-reactive genes in Asian and eastern European mice classified as M. musculus molossinus, M. musculus castaneus, and Mus musculus musculus, whereas Mus musculus domesticus from western Europe, the Mediterranean, and North America contained almost exclusively MCF virus env copies. M. musculus musculus mice from central Europe trapped near the M. musculus domesticus/M. musculus musculus hybrid zone carried multiple copies of both types of env genes. LC mice also carried both xenotropic and MCF viral env genes, which is consistent with the above conclusion that they represent natural hybrids of M. musculus domesticus and M. musculus castaneus.     

Polymorphism of the T-cell receptor gamma variable and constant region genes in a Chinese population

Summary The human T-cell receptor gamma gene region spans 160 kb genomic DNA. Restriction fragment length polymorphisms (RFLPs) have been previously documented for the constant region (TRGC) genes, the joining (TRGJ) segments and the variable (TRGV) genes. We have recently defined the alleles of the T-cell receptor gamma V, J and C genes and we have described seven haplotypes of the V gamma subgroup I genes characterized either by RFLPs or by deletion or insertion of V gamma genes. The number of VI genes may vary from 7 to 10 per haploid genome, the 9-gene haplotype being the most frequent. Allelic fragments can unambiguously characterize the TRGC2 gene with duplication or triplication of the exon 2. These alleles and haplotypes have been analyzed in four different populations (French, Lebanese, Tunisian and Black African). In this paper, we compare these allele and haplotype frequencies with those found in a Chinese population and we describe new TRGV allelic restriction fragments found only in the Chinese samples. These results and the previous data demonstrate the flexibility of the human T cell receptor gamma locus and the importance of unequal crossing-overs in the evolution of that locus. Moreover, they underline the importance of studying these polymorphisms in population genetics.     

New T-cell receptor gamma haplotypes in wild mice and evidence for limited Tcrg-V gene polymorphism

Tcrg gene polymorphism was investigated by Southern blot analysis on a panel of laboratory and wild mouse strains using a set of probes which identify all known Tcrg-V and -C genes. Only three haplotypes are found in laboratory mice: gA, gB, and gC which are represented by BALB/c, AKR, and DBA/2 prototypes respectively. gA and gC haplotypes are the most frequent among laboratory mice whereas gB is poorly represented. Seven new haplotypes are described among 23 wild mice corresponding to four Mus musculus subspecies (Mus mus domesticus, castaneus, musculus, and molossinus). However, only a few new alleles of individual genes are observed. Tcrg-V genes located at the 5 end of the Tcrg locus (V7 and V4) appear to be nonpolymorphic whereas two Tcrg-V3,-V5,-V6,-C4 and three Tcr-V1,-V2,-C1,-C2, and -C3 specific restriction fragment length polymorphisms are detected. These results indicate a relatively high degree of conservation of Tcrg genes as compared to other members of the immunoglobulin (Ig) gene family and might be related to the specificity and function of T cells. Several of the new haplotypes described here result from point mutations in noncoding Tcrg-V or -C gene-flanking regions. Recombinations may have also participated in the evolution of the Tcrg locus. Finally, these new Tcrg haplotypes are unequally distributed among the four M. m. subspecies and support the idea that the gA and gC haplotypes found in laboratory mice are inherited from M. m. domesticus whereas gB might originated from asian subspecies (castaneus, musculus or molossinus).     

Cytogenetic consequences of hybridization between wild and laboratory mice

Wild mice from the aboriginal population were crossed with the laboratory C57BL/6 mice. F1 hybrids were backcrossed with both parents. Significant increase of recombination frequency in the AY-Ra region of the 2nd chromosome (from 22.0 to 33.1 cM), of the frequency of occurrence of X-Y univalents (up to 54.6%) and of autosomal univalents (up to 9.1%) was found in the F1. In backcrosses all these induces decreased gradually.     

Generation of T-cell receptor retrogenic mice

T-cell receptor (TCR) transgenic (Tg) mice have revolutionized our understanding of many aspects of T-cell biology. Whereas they provide an almost unlimited source of T cells with a single specificity, breeding them onto different backgrounds and/or new knockout/knock-in mouse models is often time-consuming (6 months to several years), which can make the process costly and can significantly delay research. This protocol describes a new method for expressing defined TCR-alpha and TCR-beta proteins from a single 2A peptide-linked multicistronic retroviral vector in mice, using retrovirus-mediated stem cell gene transfer. We refer to these as 'retrogenic' (Rg) mice ('retro' from retrovirus and 'genic' from Tg) to avoid confusion with traditional transgenic mice. We have successfully used this approach to express over 50 different TCRs on several different mouse backgrounds in as little as 6 weeks.     

Organization of the human T-cell receptor genes

T lymphocytes recognize antigens through their membrane bound T-cell receptors. Whereas the conventional T-cell receptors are heterodimers of alpha and beta chains, expressed at the surface of CD3+ CD4+ and CD3+ CD8+ T lymphocytes, the gamma delta T-cell receptors are found at the surface of a subset of T-lymphocytes of phenotype CD3+ CD4- CD8-. The synthesis of the T-cell receptor chains results from the junction (or rearrangement) of DNA segments: Variable (V) gene and joining (J) segment for the alpha and gamma chains, V gene, D (diversity) and J segments for the beta and delta chains. In this review, we summarize the recent findings on the genomic organization of the alpha, beta, gamma and delta T-cell receptor loci in human.     

Polymorphism of transferrin found in the laboratory rat and wild rats in Japan

Polymorphism of the transferrin locus (Tf) was found in the laboratory rat and wild rats in Japan by polyacrylamide gel electrophoresis. Two phenotypes, “a” and “b,” were distinguished in homozygotes. It is suggested that these are controlled by autosomal codominant alleles. In 10 laboratory strains, only the IS strain showed the a type. This allele found in the IS strain was broadly distributed in Japanese wild rats. It is considered to be derived from a wild rat in Japan. Linkage relationship betweenTf andAlp-1 was not established.     

T-cell specific rearrangement of T-cell receptor beta transgenes in mice.

To study rearrangement of T cell receptor (TCR) genes, transgenic mice were generated with a TCR beta minilocus in germline configuration, containing three V beta, two D beta, fourteen J beta and two C beta gene segments and the TCR beta enhancer. Using the polymerase chain reaction as an analytical tool both partial DJ as well as complete VDJ rearrangements were seen, indicating that the minilocus contained all sequence elements required for rearrangment. Rearrangements of minilocus gene segments were restricted to T cells in the thymus and the periphery and did not occur in B cells. V beta 8.3 and V beta 5 sequences encoded by the minilocus were expressed on the surface of peripheral T cells at high frequencies. Transgenic mice with TCR minilocus genes will be a useful system to identify DNA sequence elements required for regulation of rearrangement in vivo.     

Sequence and diversity of rabbit T-cell receptor gamma chain genes

The nucleotide sequences of one constant (C), six variable (V), and two joining (J) gene segments coding for the rabbit T-cell receptor gamma chain (Tcrg) were determined by directly sequencing fragments amplified by the cassette-ligation mediated polymerase chain reaction. The Tcrg-C gene segment did not encode a cysteine residue for connection to the Tcr delta chain in the connecting region, and two variant forms of the Tcrg-C gene segment were generated by alternative splicing, like the human Tcrg-C2 gene. Five of six rabbit Tcrg-V gene segments belonged to the same family and displayed similarity to five productive human Tcrg-V1 family genes as well as the mouse Tcrg-V5 gene. The remaining rabbit Tcrg-V gene segment displayed similarity to the human Tcrg-V3 gene. Both rabbit Tcrg-J gene segments displayed similarity to the human Tcrg-J2.1 and 2.3, respectively. These findings suggested that the genomic organization of rabbit Tcrg genes is more similar to that of human than of mouse Tcrg genes.The nucleotide sequence data reported in this paper have been submitted to the GSDB, DDBJ, EMBL, and NCBI nucleotide sequence databases and have been assigned the accession numbers D38134-D38144 and D42090