Analysis of T cell antigen receptor (TCR) expression by human peripheral blood CD4-8- alpha/beta T cells demonstrates preferential use of several V beta genes and an invariant TCR alpha chain.

CD4-CD8- (double negative [DN]) alpha/beta T cells are a largely uncharacterized subpopulation of unknown function. To investigate whether these cells are selected to recognize particular antigens or antigen-presenting molecules, DN alpha/beta T cells were purified from the peripheral blood of five normal donors and their T cell receptor (TCR) alpha and beta chains were examined. Random cloning of TCR alpha chains by single-sided polymerase chain reaction (PCR) amplification identified an invariant rearrangement between V alpha 24 and J alpha Q, with no N region diversity, which was expressed preferentially by DN alpha/beta T cells from all donors. Random cloning also identified a precise V alpha 7.2-J alpha (IGRJa14) rearrangement, with two variable amino acids encoded in the V-J junction, which was enriched in the DN alpha/beta T cell preparations from some, but not all, donors. Analysis of TCR beta chains by quantitative PCR amplification demonstrated that the expression of four V beta gene families, V beta 2, 8, 11, and 13, was markedly increased in these DN alpha/beta T cell preparations. The expression of particular TCRs by DN alpha/beta T cells from multiple donors indicates that these cells, or at least a subpopulation of cells with this phenotype, recognize a limited spectrum of antigens and suggests that they may use nonpolymorphic antigen-presenting molecules.

cDNA cloning and characterization of mouse DTEF-1 and ETF, members of the TEA/ATTS family of transcription factors.

Members of the TEA/ATTS family of transcription factors have been found in most representative eukaryotic organisms. In vertebrates, the TEA family contains at least four members, which share overlapping DNA-binding specificity and have similar transcriptional activation properties. In this article, we describe the cDNA cloning and characterization of the murine TEA proteins DTEF-1 (mDTEF-1) and ETF. Using in situ hybridization analysis of mouse embryos, we found that mDTEF-1 and ETF transcript distributions substantially overlap. ETF is expressed throughout the embryo except in the myocardium early in development, whereas late in development, it is enriched in lung and neuroectoderm. Mouse DTEF-1 is expressed at a much lower level throughout development and is substantially enriched in ectoderm and skin, as well as in the developing pituitary at midgestation. Northern blot analysis of adult mouse tissue total RNA showed that both ETF and mDTEF-1 are abundant in uterus and lung relative to other tissues. Using gel mobility shift assays and GAL4-fusion protein analysis, we demonstrated that the full coding sequences of ETF and mDTEF-1 encode M-CAT/GT-IIC-binding proteins containing activation domains.

Detection of clonal immunoglobulin gene rearrangements by polymerase chain reaction amplification and single-strand conformational polymorphism analysis.

Analysis of immunoglobulin gene rearrangements by Southern blotting is a sensitive and specific method for detecting B cell malignancies but requires a relatively large amount of intact DNA. It cannot be utilized in many cases where only a small amount of tissue is available or where the tissue has been fixed. This report demonstrates that polymerase chain reaction (PCR) amplification in conjunction with single-strand conformational polymorphism (SSCP) analysis can be utilized to detect clonal immunoglobulin heavy chain (IgH) gene rearrangements. IgH gene rearrangements from a series of frozen or formalin-fixed B cell malignancies were PCR-amplified using oligonucleotide primers, based upon consensus sequences in the IgH variable and joining regions. Analysis of the single-stranded PCR products on nondenaturing polyacrylamide gels revealed discrete SSCPs corresponding to the malignant B cells. These SSCPs were detectable when the malignant cells represented as few as 0.2% of the total mononuclear cells in peripheral blood. PCR amplification in conjunction with SSCP analysis thus provides a sensitive and specific method to detect clonal IgH rearrangements from minute amounts of fresh, frozen, or fixed tissue.

cDNA cloning and characterization of murine transcriptional enhancer factor-1-related protein 1, a transcription factor that binds to the M-CAT motif.

The M-CAT motif is a cis-regulatory DNA sequence that is essential for muscle-specific transcription of several genes. Previously, we had shown that both muscle-specific (A1) and ubiquitous (A2) factors bind to an essential M-CAT motif in the myosin heavy chain beta gene and that the ubiquitous factor is transcriptional enhancer factor (TEF)-1. Here we report the isolation of mouse cDNAs encoding two forms (a and b) of a TEF-1-related protein, TEFR1. The TEFR1a cDNA encodes a 427-amino acid protein. The coding region of TEFR1b is identical to 1a in both nucleotide and predicted amino acid sequence except for the absence of 43 amino acids downstream of the TEA DNA-binding domain. Three TEFR1 transcripts (approximately 7, approximately 3.5, and approximately 2 kilobase pairs) are enriched in differentiated skeletal muscle (myotubes) relative to undifferentiated skeletal muscle (myoblasts) and non-muscle cells in culture. In situ hybridization analysis indicated that TEFR1 transcripts are enriched in the skeletal muscle lineage during mouse embryogenesis. Transient expression of fusion proteins of TEFR1 and the yeast GAL4 DNA-binding domain in cell lines activated the expression of chloramphenicol acetyltransferase (CAT) reporter constructs containing GAL4 binding sites, indicating that TEFR1 contains an activation domain. An anti-TEFR1 polyclonal antibody supershifted the muscle-specific M-CAT.A1 factor complex in gel mobility shift assays, suggesting that TEFR1 is a major component of this complex. Our results suggest that TEFR1 might play a role in the embryonic development of skeletal muscle in the mouse.

Human intestinal intraepithelial lymphocytes are derived from a limited number of T cell clones that utilize multiple V beta T cell receptor genes.

Intestinal intraepithelial lymphocytes (IEL) are a phenotypically distinct T cell population of unknown function. The majority of human intestinal IEL express the TCR-alpha beta, the CD8 accessory molecule, and the CD45RO Ag, suggesting that they are MHC class I-restricted memory T cells. Recent analyses of the TCR alpha- and beta-chains expressed by these cells have shown marked skewing toward one or several V region genes in individual donors and revealed the presence of clonally expanded cells. In addition, functional data has suggested that the MHC class I-like CD1 molecules may be the target ligands for some human intestinal IEL clones. This report examines in detail the TCR-beta repertoire of human jejunal IEL to determine what fraction of these cells are clonally expanded and to determine whether a particular subset of V beta genes are utilized by the clonally expanded cells. The results demonstrate that the majority of IEL are derived from the expansion of a relatively few T cell clones and that these clones can utilize a large number of different V beta genes. Oligoclonal expansion is also demonstrated among lamina propria lymphocytes (LPL), with overlapping but distinct clones detected in the LPL vs the IEL populations. These results indicate that most intestinal IEL-alpha beta, and a subpopulation of LPL, are specific for a limited number of Ag and place constraints on the possible roles played by IEL in the defense against diverse environmental pathogens or in the generation of oral tolerance.

Muscle-specific regulation of a transfected rabbit myosin heavy chain beta gene promoter.

We have examined the transcriptional regulation of the rabbit myosin heavy chain (HC) beta gene by using DNA-mediated transfection experiments. To analyze the activity of the myosin HC beta promoter in a myogenic background, cultured myoblasts from 12-day-old chick embryonic breast muscle were transfected with a chimeric gene containing 781 base pairs of the promoter region fused to the gene for chloramphenicol acetyltransferase (CAT). As indicated by the transient expression of chloramphenicol acetyltransferase, the activity of the promoter in myoblast cultures increased at least 32-fold following differentiation and was selectively inhibited when myogenesis was blocked with 5-bromodeoxyuridine. Furthermore, RNase protection experiments showed that the in vivo myosin HC beta transcriptional initiation (or cap) site was utilized in the transfected skeletal muscle cells and also that the regulation of the exogenous promoter was similar to the induction of the endogenous skeletal alpha-actin gene. The results indicated that the exogenous promoter is regulated in a tissue- and stage-specific manner. By creating progressive 5' deletions of the promoter, we showed that only the region extending -294 base pairs upstream from the cap site is necessary for the muscle-specific expression. Linker-scanner mutagenesis of this region indicated that the positive regulation in differentiated skeletal muscle is mediated by at least two distinct elements within the 5'-flanking region of the myosin HC beta gene.