Assignment of the gene coding for the T3-delta subunit of the T3-T-cell receptor complex to the long arm of human chromosome 11 and to mouse chromosome 9

N-terminal negatively charged residues in CD3varepsilon chains as a phylogenetically conserved trait potentially yielding isoforms with different isoelectric points: analysis of human CD3varepsilon chains

CD3varepsilon chains are essential to the structure, expression and signaling of T cell receptors. Here, we extend to human CD3varepsilon our previous data in mouse CD3varepsilon showing that, in T cells, proteolytic processing of the acidic N-terminal sequence of CD3varepsilon chains generate distinct polypeptide species that can be identified by two-dimension (IEF-SDS PAGE) electrophoresis and immunoblot. This was shown first by showing the processing of a fusion protein of GFP and the extracellular domain of mouse CD3varepsilon (mCD3GFP) expressed in Jurkat cells. Secondly, pI heterogeneity was also found in human CD3varepsilon chains immunoprecipitated from the surface of Jurkat cells or PHA blasts of human blood T lymphocytes. Comparison of CD3varepsilon chains from 27 different species shows that their N-terminal sequences share a strong acidic nature, despite the large differences in terms of length and composition, even among closely related species. Our results suggest that generation of CD3varepsilon chain isoforms with different N-terminal sequence and pI is a general phenomenon. Thus, as previously observed in the mouse, the relative abundance of CD3varepsilon chain species might regulate TCR/CD3 structure and function, including the strength of the interactions between CD3 dimers and the TCR clonotypic receptors, as well as TCR/CD3 activation thresholds. Interestingly, CD3varepsilon chains from 7 out of 27 species studied have putative N-glycosylation (NxS or NxT) motifs in their Ig extracellular domain. Their location, plus the conservation of residues involved in domain organization, the interactions with other CD3 chains, or the TCR, and signal triggering add new data useful to establish a permissive topology for the interaction between CD3 dimers and the TCR chains.

Lineage promiscuous expression of transcription factors in normal hematopoiesis

Hematopoiesis has provided a valuable model for examining how genetic programs are established and executed in terms of cell fate decision. Identification of common myeloid and lymphoid progenitors allows us to directly assess the regulatory mechanisms of lineage commitment. Multiple markers of hematopoietic lineages are coexpressed in hematopoietic stem cells and progenitors, a phenomenon referred to as lineage priming. Promiscuous expression of several lineage-affiliated genes precedes lineage commitment but does not alter the biological potential of hematopoietic stem cells and multipotent progenitors. Promiscuous accessibility of multiple programs allows flexibility in cell fate commitment at the multipotent stages, indicating that transcriptional promiscuity can operate in stem cells and progenitors to control their transition from multipotency to single-lineage commitment.

Myeloid or lymphoid promiscuity as a critical step in hematopoietic lineage commitment

We demonstrate here that "promiscuous" expression of myeloid or lymphoid genes precedes lineage commitment in hematopoiesis. Prospectively purified single common myeloid progenitors (CMPs) coexpress myelo-erythroid but not lymphoid genes, whereas single common lymphoid progenitors (CLPs) coexpress T and B lymphoid but not myeloid genes. Genes unrelated to the adopted lineage are downregulated in bipotent and monopotent descendants of CMPs and CLPs. Promiscuous gene expression does not alter the biological potential of multipotent progenitors: CMPs with an activated endogenous M lysozyme locus yield normal proportions of myelo-erythroid colonies, and CLPs expressing the pre-T cell receptor alpha gene differentiate into normal numbers of B cells. Thus, the accessibility for multiple myeloid or lymphoid programs promiscuously may allow flexibility in fate commitments at these multipotent stages.

Pancreatic islet cells express a family of inwardly rectifying K+ channel subunits which interact to form G-protein-activated channels

Insulin secretion is associated with changes in pancreatic beta-cell K+ permeability. A degenerate polymerase chain reaction strategy based on the conserved features of known inwardly rectifying K+ (KIR) channel genes was used to identify members of this family expressed in human pancreatic islets and insulinoma. Three related human KIR transcript sequences were found: CIR (also known as cardiac KATP-1), GIRK1, and GIRK2 (KATP-2). The pancreatic islet CIR and GIRK2 full-length cDNAs were cloned, and their genes were localized to human chromosomes 11q23-ter and 21, respectively. Northern blot analysis detected CIR mRNA at similar levels in human islets and exocrine pancreas, while the abundance of GIRK2 mRNA in the two tissues was insufficient for detection by this method. Using competitive reverse-transcription polymerase chain reaction, CIR was found to be present at higher levels than GIRK2 mRNA in native purified beta-cells. Xenopus oocytes injected with M2 muscarinic receptor (M2) plus either GIRK2 or CIR cRNA expressed only very small carbachol-induced currents, while co-injection of CIR plus GIRK2 along with M2 resulted in expression of carbachol-activated strong inwardly rectifying currents. Activators of KATP channels failed to elicit currents in the presence or absence of co-expressed sulfonylurea receptor. These results show that two components of islet cell KIR channels, CIR and GIRK2, may interact to form heteromeric G-protein-activated inwardly rectifying K+ channels that do not possess the typical properties of KATP channels.

The human interleukin-10 receptor gene maps to chromosome 11q23.3

The human interleukin-10 receptor (IL-10R) gene has previously been mapped to chromosome 11. Here, we have determined the precise location of the human IL-10R gene by the fluorescence in situ hybridization method, and have found that the IL-10R gene maps to chromosome 11q23.3.

T cell development in CD3-zeta mutant mice

Increasing evidence points to multiple pathways of T lymphocyte development. The well characterized thymus-dependent pathway gives rise to T cells bearing TCR alpha beta heterodimers and either CD4 or CD8 alpha beta co-receptors. T cells of this lineage populate peripheral lymphoid compartments including lymph nodes, spleen, skin, and Peyer's patches. By comparison, factors which govern extrathymic T cell development are poorly understood. A variety of experiments have shown that intestinal intraepithelial lymphocytes (IELs) develop outside of the thymic environment, e.g., in the gut of nude, SCID, and beta 2m-/- mutant mice, and after transplanting bone marrow or fetal liver cells into irradiated thymectomized adult mice. This review focuses on the role of the CD3-zeta subunit in the development of both thymically and extrathymically derived T cells as determined by gene-targeting experiments in mice. Data from these and other T cell-related mutations continue to define crucial stages in thymocyte differentiation. Most interestingly, CD3-zeta mutant mice contain a unique population of intestinal IELs that develops independently of thymic selective processes and expresses a novel TCR/CD3 complex.

Possible association of CD3 and CD4 polymorphisms with insulin-dependent diabetes mellitus (IDDM)

Population and family studies show that predisposition to type I diabetes (IDDM) is multifactorial, and that polymorphisms in the MHC region contribute substantially to the susceptibility to IDDM. In the present study the association of polymorphisms in the CD4 and the delta subunit of CD3 with IDDM were examined in a Belgian population. We observed that the frequency of the CD A4/A4 genotype and of the CD3 91 allele were significantly increased P = 0.0077) and decreased (P = 3.8 x 10(-5), respectively, in IDDM compared with controls. These results therefore suggest that CD4, CD3 or neighbouring genes might contribute to IDDM susceptibility. These results are, however, preliminary and cannot be considered as established until re-tested in a new population.

T cell receptor complexes containing Fc epsilon RI gamma homodimers in lieu of CD3 zeta and CD3 eta components: a novel isoform expressed on large granular lymphocytes

CD3 zeta and CD3 eta form disulfide-linked homo- or heterodimers important in targeting partially assembled Ti alpha-beta/CD3 gamma delta epsilon T cell receptor (TCR) complexes to the cell surface and transducing stimulatory signals after antigen recognition. Here we identify a new TCR isoform expressed on splenic CD2+, CD3/Ti alpha-beta+, CD4-, CD8-, CD16+, NK1.1+ mouse large granular lymphocytes (LGL), which are devoid of CD3 zeta and CD3 eta proteins. The TCRs of this subset contain homodimers of the gamma subunit of the high affinity receptor for IgE (Fc epsilon RI gamma) in lieu of CD3 zeta and/or CD3 eta proteins. The LGL display natural killer-like activity and are cytotoxic for B cell hybridomas producing anti-CD3 epsilon and anti-CD16 monoclonal antibodies, demonstrating the signaling capacity of both TCR and CD16 in this cell type. These findings provide evidence for an additional level of complexity of TCR signal transduction isoforms in naturally occurring T cell subsets.

Differential signal transduction via T-cell receptor CD3 zeta 2, CD3 zeta-eta, and CD3 eta 2 isoforms

The T-cell antigen receptor (TCR) consists of an antigen-binding heterodimer, termed Ti, which is noncovalently associated with the invariant CD3 subunits (gamma, delta, epsilon, zeta, and eta). The CD3 zeta and -eta subunits form either homodimeric or heterodimeric structures in turn associated with the other components of the TCR complex. This feature increases the structural complexity of TCRs by creating "isoforms." Both CD3 zeta and -eta are thought to play an important role in signal transduction triggered by antigen/major histocompatibility complex. To compare signaling functions of TCR isoforms, MA5.8, a CD3 zeta-eta- variant of the cytochrome c-specific, I-Ek-restricted T-cell hybridoma 2B4.11, was stably transfected with cDNAs encoding CD3 zeta and/or CD3 eta, and resulting clones were characterized. The findings indicate that signals inducing Ca2+ mobilization, phosphatidylinositol turnover, and interleukin 2 production are each transmitted by the above TCR isoforms. In contrast, tyrosine phosphorylation of the CD3 zeta subunit but not the CD3 eta subunit follows TCR stimulation. Given the general importance of tyrosine phosphorylation for receptor signaling, it is likely that this difference between TCR isoforms plays a regulatory role in T-lineage function by qualitatively or quantitatively altering signaling events.

Genetic reconstitution of the T cell receptor (TcR) alpha/beta heterodimer restores the association of CD3 zeta 2 with the TcR/CD3 complex

The cell surface expression of the T cell receptor (TcR)/CD3 complex and, consequently, the functional competence of the cell is partly dependent on CD3 zeta. In its absence, a pentameric complex (TcR alpha/beta/CD3 gamma delta epsilon) is formed which is inefficiently transported to the cell surface. Reconstitution of CD3 zeta by transfection, in turn, restores the cell surface expression and function of the complex. Through the use of transfection experiments, we here provide direct evidence that the association of CD3 zeta 2 with the TcR/CD3 complex is dependent on the presence of both the TcR alpha and beta polypeptide chains. Despite wild-type levels of the CD3 zeta protein in a TcR alpha-negative mutant human T cell line, a complex was formed intracellularly which lacked CD3 zeta 2 and consisted of beta gamma delta epsilon and beta 2 gamma delta epsilon. Upon transfection of the mutant with a TcR alpha cDNA, a TcR/CD3 complex which contained CD3 zeta 2 was observed intracellularly. In contrast to the partial subcomplex on the cell surface of the untransfected cell line, the TcR/CD3 complex on the transfectant was functional as demonstrated by its ability to mobilize intracellular calcium after stimulation with a mitogenic CD3 epsilon-specific monoclonal antibody. Transient transfection studies performed in COS cell fibroblasts indicated that CD3 zeta 2 was not interacting with the TcR alpha protein alone, implying that a conformation provided by either the TcR alpha/beta heterodimer or the TcR alpha/beta/CD3 gamma delta epsilon complex was necessary for the association of CD3 zeta 2. Transfection studies performed in a TcR alpha/beta-negative murine T-T hybridoma confirmed the requirement of both the TcR alpha and beta proteins in CD3 zeta 2 binding. We conclude that the TcR alpha and beta chains harbor polypeptide sequences essential for the association of CD3 zeta 2 with the TcR/CD3 complex.

Familial pericentric inversion of chromosome 11 in a child with sporadic unilateral retinoblastoma

The authors treated a 12-month-old Japanese boy with sporadic unilateral retinoblastoma and hereditary chromosomal inversion inv(11)(p11q23). This chromosomal inversion was also present in the father of the boy. Cytogenetic analyses of the mother and sister were normal. Retinoblastoma is associated with constitutional deletion of the long arm of chromosome 13. The breakpoint in the chromosome 11q23 region is involved in several malignant hematological diseases, and may be important in malignant transformation. Therefore, a large number of such patients with pericentric inversion of chromosome 11 has to be identified before significance of this chromosomal abnormality can be determined.

Characterization of thymus-derived lymphocytes expressing Ti alpha-beta CD3 gamma delta epsilon zeta-zeta, Ti alpha-beta CD3 gamma delta epsilon eta-eta or Ti alpha-beta CD3 gamma delta epsilon zeta-zeta/zeta-eta antigen receptor isoforms: analysis by gene transfection

To characterize the function of the CD3 eta subunit of the T cell receptor (TCR), we have used cDNAs encoding CD3 zeta, CD3 eta, or both to reconstitute a variant of a cytochrome c-specific, I-Ek-restricted murine T cell hybridoma, termed MA5.8, which lacks CD3 zeta and CD3 eta proteins. We provide direct evidence that assembly and surface expression of TCRs can be mediated by either of these subunits separately or together. However, the level of TCR expression on zeta transfectants is up to one order of magnitude greater than that on eta transfectants, implying that CD3 eta is weakly associated with the pentameric Ti alpha-beta CD3 gamma delta epsilon complex and/or inefficient at salvaging the incomplete TCR from lysosomal degradation. As a component of the TCR, the CD3 eta subunit preferentially forms a heterodimer with CD3 zeta, but is also able to form a CD3 eta-eta homodimer. Crosslinking of Ti alpha-beta CD3 gamma delta epsilon zeta-zeta, Ti alpha-beta CD3 gamma delta epsilon eta-eta, or Ti alpha-beta CD3 gamma delta epsilon zeta-zeta/zeta-eta TCR isotypes with anti-CD3 epsilon monoclonal antibody or a cytochrome c peptide epitope on I-Ek antigen-presenting cells mediates signal transduction resulting in reversible cell-cycle arrest of transfected clones. Given the potential for diversity of signals generated by these functional TCR isotypes and the expression of the CD3 eta gene product in the thymus, CD3 eta is likely to play a role in selection and/or activation of thymocytes during development.

Localization of gene for human syndecan, an integral membrane proteoglycan and a matrix receptor, to chromosome 2

Syndecan, a cell surface proteoglycan, is an integral membrane protein acting as a receptor for the extracellular matrix. For chromosomal localization of the human syndecan gene, a panel of mouse-human somatic cell hybrids was analyzed by Southern blotting using the cDNA probe for human syndecan. The hybrids were karyotyped at the time of DNA extraction. A band corresponding to the human syndecan gene in Southern blots was found only in a hybrid cell line containing human chromosome 2. This hybrid was subcloned and its subclones were analyzed by Southern blotting and karyotyped. Subclones carrying human chromosome 2 contained the syndecan gene, while subclones not carrying this chromosome did not. The human syndecan gene is thus assigned to chromosome 2.

Gene for human CD59 (likely Ly-6 homologue) is located on the short arm of chromosome 11

The CD59 (MEM-43) antigen, which probably is a human homologue of mouse Ly-6 antigens, is a broadly expressed Mr 18,000-25,000 human leucocyte surface glycoprotein recognized by monoclonal antibody MEM-43. Ten mouse-human T-lymphocyte hybrids, carrying all mouse chromosomes and a limited number of human chromosomes, were analyzed for expression of CD59 by indirect immunofluorescence and immunoblotting with MEM-43 antibody. Karyotypic analysis of the tested clones showed that the presence of human chromosome 11 correlated with the expression of CD59 in all clones tested. Three other human chromosome 11-encoded antigens, 4F2 (Trop-4), Leu 7 (HNK-1, CD57), and lymphocyte homing receptor, were expressed concordantly with CD59. A more exact localization of the gene for CD59 was obtained by the study of Chinese hamster-human cell hybrids containing short or long arm deletions of human chromosome 11. CD59 segregated with hybrids containing part of the short arm of human chromosome 11, but not with the hybrids containing the long arm. Based on these studies we assign the gene for CD59 to region p14-p13 of the short arm of chromosome 11.

A molecular genetic linkage map of mouse chromosome 9 with regional localizations for the Gsta, T3g, Ets-1 and Ldlr loci

A 64-centiMorgan linkage map of mouse chromosome 9 was developed using cloned DNA markers and an interspecific backcross between Mus spretus and the C57BL/6J inbred strain. This map was compared to conventional genetic maps using six markers previously localized in laboratory mouse strains. These markers included thymus cell antigen-1, cytochrome P450-3, dilute, transferrin, cholecystokinin, and the G-protein alpha inhibitory subunit. No evidence was seen for segregation distortion, chromosome rearrangements, or altered genetic distances in the results from interspecific backcross mapping. Regional map locations were determined for four genes that were previously assigned to chromosome 9 using somatic cell hybrids. These genes were glutathione S-transferase Ya subunit (Gsta), the T3 gamma subunit, the low density lipoprotein receptor, and the Ets-1 oncogene. The map locations for these genes establish new regions of synteny between mouse chromosome 9 and human chromosomes 6, 11, and 19. In addition, the close linkage detected between the dilute and Gsta loci suggests that the Gsta locus may be part of the dilute/short ear complex, one of the most extensively studied genetic regions of the mouse.

Molecular cloning and chromosomal localization of the human T-cell receptor zeta chain: distinction from the molecular CD3 complex

The T-cell antigen receptor (TCR) is a multisubunit receptor complex specific to T cells subserving both antigen recognition and signal transduction functions. The zeta chain of the TCR is a component of all surface receptor complexes. This chain was first identified in murine T cells by virtue of the fact that it coimmunoprecipitates with the TCR complex using antibodies directed against either the clone-specific subunits or invariant CD3 subunits of the receptor. Recently, we have isolated a cDNA encoding the murine zeta. Using this as a probe, we have now isolated cDNAs encoding the human zeta. Sequence analysis of cDNAs encoding human and murine zeta reveals that it is a highly conserved protein. In addition to amino acid homology, there is remarkable interspecies conservation in the nucleotide sequence of the 5' and 3' untranslated regions of the zeta mRNA. The previously characterized invariant delta, epsilon, and gamma chains of the TCR, referred to as the CD3 complex, share significant sequence and structural homology with each other and are all located within 300 kilobases of each other on human chromosome 11 (11q23). zeta has no sequence similarity to the CD3 chains and the localization of the human zeta gene to the centromeric region of chromosome 1 underscores the fact that it is a distinct genetic component of the TCR.

Presence of the long chain form of polysialic acid of the neural cell adhesion molecule in Wilms' tumor. Identification of a cell adhesion molecule as an oncodevelopmental antigen and implications for tumor histogenesis

The long chain form of polysialic acid characteristic of the low adhesive embryonic form of the neural cell adhesion molecule NCAM is temporally and spatially expressed in developing kidney but undetectable in normal adult kidney. Therefore, this molecule represents a developmentally regulated antigen in kidney contrasted with neural tissue, where it is also detectable in the adult brain. This investigation of 25 Wilms' tumors comprising all different histologic types demonstrates expression of this molecule under conditions of malignant growth. Immunostaining was observed in Wilms' tumors with both a monoclonal anti-polysialic acid antibody and a polyclonal anti-NCAM polypeptide antiserum. Intense cell surface staining sensitive to endosialidases specifically hydrolyzing alpha 2,8 linked (poly)sialic acid was detectable in blastemal regions, and weaker, variable labeling was seen over tubules and glomeruloid bodies. The stroma was not stained. This is evidence indicating that Wilms' tumor originates from the embryonic equivalent of induced metanephrogenic mesenchyme. It seems unlikely however, that the stroma is derived from the blastema. The same high molecular mass broad band typical of the embryonic form of NCAM was revealed by immunoblot analysis of homogenates from Wilms' tumor as well as from embryonic kidney and brain. In situ hybridization demonstrated the presence of mRNA for NCAM in all but stromal elements of Wilm's tumors. Thus, polysialic acid is present on NCAM and represents a new oncodevelopmental antigen in human kidney. Polysialic acid was greatly reduced or absent by immunohistochemistry and immunoblotting in necrotic tumor areas.

Characterization and expression of the murine CD3-epsilon gene

The receptor for antigen on the surface of T lymphocytes consists of a variable disulfide-bridged hetero-dimer (TCR-alpha/beta or -gamma/delta) associated with invariant CD3 proteins (CD3-gamma, -delta, -epsilon, and -zeta). The genes coding for the CD3 proteins are expressed in the earliest recognizable thymocytes, preceding the rearrangement and expression of the TCR genes. The isolation, characterization, and in vitro expression of the murine CD3-epsilon gene, as reported here, represent obligatory steps toward our understanding of the complex rules that govern T-cell-specific gene expression. The CD3-epsilon gene was transcribed from a non-TATA promoter and consisted of eight exons, two of which were unusually small (18 and 15 base pairs). The transmembrane exon was found to be homologous to the transmembrane exons of the CD3-gamma and CD3-delta genes. In transient-transfection experiments, a genomic fragment comprising 4 kilobases of upstream sequence and extending into the second exon sufficient to drive the expression of a reporter gene in murine T cells.

Molecular organization of the human CD3 gene family on chromosome 11q23

The genes encoding three invariant components of the human T-cell antigen receptor, the CD3 delta, gamma, and epsilon chains, are located on human chromosome 11 at band q23. We isolated cosmid clones containing the human CD3 delta and gamma chain genes in vectors designed for rapid and efficient chromosome "walking". The human CD3 epsilon gene was located in the region immediately downstream of the CD3 delta and gamma genes using synthetic oligonucleotide probes and the localization of this gene confirmed by DNA sequencing. Detailed restriction mapping of the CD3 locus demonstrated that all three CD3 subunits are encoded within 60 kb of DNA with the CD3 epsilon gene located 26 kb downstream of the CD3 delta and gamma genes. Analysis of genomic DNA on pulsed field gels using probes isolated from these cosmid clones defined a physical map of 750 kb spanning the CD3 locus on human chromosome 11q23. The CD3 genes thus comprise a multigene family encoding cell surface components important for transmembrane signaling on T lymphocytes. The arrangement of these genes suggest that they may share common regulatory elements for the control of gene expression during T-cell ontogeny.

Human CD3-epsilon gene contains three miniexons and is transcribed from a non-TATA promoter

The antigen receptor of the T lymphocyte consists of two variable T-cell receptor chains (either TCR-alpha, TCR-beta or TCR-gamma, TCR-delta) noncovalently linked to four different invariant membrane proteins (CD3-gamma, CD3-delta, CD3-epsilon, and the CD3-zeta homodimer). The CD3 genes are expressed early in thymocyte development, preceding the rearrangement and expression of the T-cell receptor genes. Here we report the isolation and structural analysis of the human CD3-epsilon gene. The gene consisted of nine exons. Three exons, encoding the junction of leader peptide and mature protein, were extremely small (21, 15, and 18 base pairs, respectively). The murine gene contained only two such miniexons, the sequences of which were not homologous to those of the three human miniexons. But from comparisons of intron sequences the regions surrounding the human miniexons III and IV appeared to be closely related to those surrounding the murine miniexons III and IV. The most-3' miniexon in the human gene (IVa) had no murine counterpart and appeared not to duplicate any of the other miniexons. Sequence analysis of CD3-epsilon cDNA clones isolated from four independent libraries gave no evidence for alternative use of these miniexons. Like CD3-delta, the CD3-epsilon gene was transcribed from a weak, nontissue-specific, TATA-less promoter. Pulsed-field electrophoresis showed that the human CD3-epsilon gene was separated from the CD3-gamma, CD3-delta gene pair by at least 30 kilobases, but by no more than 300 kilobases.

Expression of human CD4 by two human-mouse interlineage hybrids

Two hybrid cell lines expressing human CD4 were prepared by fusing human B-lymphoid cells with the mouse T-lymphoma BW5147. Hybrid TF42 was derived from a human B-lymphoblastoid line and TF53.1 from a human B-ALL. Variants of these hybrids expressing or lacking CD4 were isolated by sorting cells stained with the monoclonal antibody (mAb) OKT4 on a fluorescence-activated cell sorter (FACS). Cytogenetic, isoenzyme and DNA analysis confirmed the presence of human chromosome 12 in the CD4+ hybrids, and revealed that CD4 expression by TF42 was associated with multiple copies of this chromosome. Of seventy mAb recognizing human T-cell antigens screened on the CD4+ and CD4- variants of the two hybrids, only mAb recognizing CD4 and Leu 8 reacted with the CD4+ cells. These hybrids should be useful in the preparation, screening and analysis of anti-CD4 monoclonal antibodies, and in studies of CD4 epitopes recognized by HIV.

Molecular cloning of the zeta chain of the T cell antigen receptor

The T cell antigen receptor is a multi-subunit receptor complex present on the surface of all mature and many developing T cells. It consists of clonotypic heterodimers noncovalently linked to five invariant chains that are encoded by four genes and referred to as the CD3 complex. The CD3 gamma, delta, and epsilon chains have been molecularly characterized. In this report the molecular cloning of a complementary DNA encoding the zeta chain of the murine T cell antigen receptor is described. The predicted protein sequence of the zeta chain suggests a structure distinct from those of any of the previously described receptor subunits.

Expression of human CD antigens, including CD1 and CD25, by human x mouse interlineage leukaemia hybrids

The expression of human cell-membrane antigens by hybrid cell lines derived by fusing a human B-ALL and mouse BW 5147 T-lymphoma cells has been studied. Using monoclonal antibodies (mAb), the phenotypes of 19 of the 24 hybrids which grew 11-44 days post-fusion have been analysed by indirect membrane immunofluorescence (IF). These uncloned hybrid cells were assayed early after outgrowth, prior to extensive human chromosome and antigen loss. Nonetheless, cytogenetic analysis showed that all hybrids contained variable numbers of human chromosomes. Phenotypic analysis showed that the hybrids could be grouped as follows: a high frequency expressing CD25 (IL-2 receptor), human T200, HLA class I alpha and beta 2microglobulin, and reacting with the mAb H207 and 12E7; an intermediate frequency expressing CD1 and CD2; and a low frequency expressing CD3, CD4, CD5, CD7, CD8 and CD9. This pattern of antigen expression resembled the frequency of these cells in the human B-ALL parent line. Cell sorting was used to immunoselect hybrids expressing CD1 and CD2, but CD1 expression was unstable during subsequent culture.

Close linkage of the mouse and human CD3 gamma- and delta-chain genes suggests that their transcription is controlled by common regulatory elements

Antigen receptors on the T-cell surface are noncovalently associated with at least four invariant polypeptide chains, CD3-gamma, -delta, -epsilon, and -zeta. The mouse CD3-gamma gene, consisting of seven exons, was found to be highly homologous to the CD3-delta gene described earlier. Both the high level of sequence homology and the exon/intron organization indicate that the CD3-gamma and -delta genes arose by gene duplication. Surprisingly, murine and human genomic DNA clones could be isolated that contained elements of both the CD3-gamma and CD3-delta genes. In fact, the putative transcription start site of the mouse CD3-gamma gene is less than 1.4 kilobases from the transcription initiation site of the mouse CD3-delta gene. Common elements that regulate the divergent transcription of the two genes are therefore proposed to be located in the intervening 1.4-kilobase DNA segment. This might contribute to the coordinate expression of the CD3-gamma and -delta genes during intrathymic maturation of T lymphocytes.

Localization of the human progesterone receptor gene to chromosome 11q22-q23

The human progesterone receptor gene was mapped by in situ hybridization using two cDNA probes corresponding to the 5' and 3' part of the coding sequence. This gene was localized to 11q22-q23.

Evolutionary relationship between the T3 chains of the T-cell receptor complex and the immunoglobulin supergene family

Antigen receptors on the surface of the thymus-derived (T) lymphocytes are associated with small integral membrane proteins called the T3 (CD3) gamma, delta, epsilon, and zeta chains. After interaction of the T-cell receptor with antigen, the T3 proteins are believed to transfer an activation signal to the intracellular compartment. In previous studies, the human gamma, epsilon, and delta chains have been cloned along with the mouse delta chain, but a relationship between these sequences and known molecular families has not been established. We now report the molecular cloning and characterization of the murine T3-epsilon protein and a sequence and structural analysis of the relationships between all the T3 chains and the immunoglobulin superfamily. It is established that the T3 chains are immunoglobulin-related and a particular relationship to the neural cell adhesion molecule (N-CAM) is noted. This sequence relationship adds interest to previous findings that the T3 chains are genetically linked to N-CAM and Thy-1 antigen on band q23 of human chromosome 11.

The gene encoding the epsilon subunit of the T3/T-cell receptor complex maps to chromosome 11 in humans and to chromosome 9 in mice

The T3 complex is composed of three polypeptide chains that are both structurally and functionally associated with the receptor for antigen on the surface of human T lymphocytes. In a series of experiments utilizing both somatic cell hybrids and chromosomal hybridization in situ, the genes encoding two members of the human T3 complex, T3-delta and T3-epsilon, were found to reside on the long arm of chromosome 11 in band q23. The murine T3-epsilon gene was localized to chromosome 9. The location of the T3-delta and T3-epsilon genes with respect to the Hu-ets-1 gene, which is also located in 11q23, is discussed. Recent assignments of several genes, preferentially expressed in human cells of hematopoietic and neuroectodermal origins, to band q23 of human chromosome 11 and the murine equivalents to murine chromosome 9 may define a conserved gene cluster important in cell proliferation and differentiation.

Chromosomal locations of the gene coding for the CD3 (T3) gamma subunit of the human and mouse CD3/T-cell antigen receptor complexes

The gene coding for the Mr 26000 gamma chain of the human CD3 (T3) antigen/T-cell antigen receptor complex was mapped to chromosome band 11q23 by using a cDNA clone (pJ6T3 gamma-2), by in situ hybridization to metaphase chromosomes and by Southern blot analysis of a panel of human-rodent somatic cell hybrids. The mouse homolog, here termed Cdg-3, was mapped to chromosome 9 using the mouse gamma cDNA clone pB10.AT3 gamma-1 and a panel of mouse-hamster somatic cell hybrids. Similar locations for the CD3 delta genes have been described previously. Thus, the corporate results indicate that the CD3 gamma and delta genes have remained together since they duplicated about 200 million years ago.

Polymorphism for RhT3, a CD3-like cell surface antigen, expressed on rhesus monkey T lymphocytes

The target antigen of the FN18 monoclonal antibody, called RhT3, is probably the rhesus monkey homologue of the human CD3 antigen, expressed on mature T cells. RhT3 appears to be polymorphic, since FN18 was not reactive with T cells from all the screened animals. Thus, immunofluorescent staining of peripheral blood lymphocytes with FN18 antibody revealed either a positive or a negative phenotype for the target antigen. In a rhesus monkey population, nonreactivity for FN18 was observed in low frequency (2.7%). Expression and non-expression of RhT3 appeared to be constant characteristics. Non-expression was not associated with any demonstrable immunodeficiency. Further, there seemed to be no association between the presence of the FN18 target antigen and sex, age or expression of MHC class I antigens. Family studies indicated that the positive phenotype is expressed in the same fashion by animals presumably heterozygous or homozygous for the positive allele, the negative phenotype being expressed only on cells from animals homozygous for an assumed blank allele. Therefore, the positive phenotype is likely to be transmitted in an autosomal dominant mode. In the animals with the negative phenotype, normal T-cell numbers were present, as was demonstrated by B- and T-cell specific monoclonal antibodies. Cytoplasmic staining of cytospun lymphocyte preparations with FN18 revealed that polymorphism was present at the intracellular level. Cell proliferation tests, using PWM and Con A as mitogens, showed the presence of apparently functional RhT3 cell surface molecules in FN18 non-reactive animals. Polymorphism is therefore assumed to be at the epitope level.

Negative trans-regulation of T-cell antigen receptor/T3 complex mRNA expression in murine T-lymphoma somatic cell hybrids

The antigen-specific T-cell receptor (TCR) is composed of variable antigen-recognition chains TCR-alpha and TCR-beta in noncovalent association with the invariant T3 multimer. The TCR-alpha and TCR-beta chains are encoded by gene segments that must be juxtaposed by rearrangement in order to be expressed. To examine whether mechanisms other than gene rearrangement might regulate TCR/T3 gene expression, somatic cell hybrids were formed among closely related murine SL12 T-lymphoma clones that differ in TCR/T3 mRNA levels. In hybrid cells formed between cell clones in which one parent is TCR-beta+ and the other is TCR-beta-, the resultant hybrid cells lack detectable TCR-beta transcripts. Since the protein synthesis inhibitor cycloheximide partially reverses TCR-beta repression in the hybrid cells, we postulate that a labile repressor protein is involved. The amount of mRNA encoding one of the T3 polypeptide chains, T3-delta, is also strongly negatively transregulated in the same hybrid cells in which TCR-beta mRNA expression is repressed. The negative trans-regulation of TCR-beta and T3-delta mRNA expression is relatively specific, since the levels of TCR-alpha mRNA and several thymocyte surface antigens are not repressed in somatic cell hybrids. Our results indicate that rearrangement of the TCR genes alone is not sufficient for TCR-beta expression and that trans-acting factors regulate the amounts of both TCR-beta and T3-delta mRNA in this system.

Comparison of constitutional and tumor-associated 11;22 translocations: nonidentical breakpoints on chromosomes 11 and 22

Recurring, site-specific chromosomal rearrangements are associated with several human syndromes and malignant disorders. Such nonrandom translocations involving chromosome 22 in band q11 are numerous and found to be associated with a diversity of neoplasms as well as constitutional disorders. Chromosome 11 in bands q23-q24 is similarly involved in several types of tumors as well as in a recurring constitutional reciprocal translocation with chromosome 22. Here we report the use of chromosomal in situ hybridization to compare the translocation breakpoints in the cytologically indistinguishable constitutional t(11;22) and the tumor-related t(11;22) associated with Ewing sarcoma and peripheral neuroepithelioma. We have shown that the breakpoints can be distinguished from each other with respect to the locus encoding the constant region of the Ig lambda light chain (C lambda) at 22q11 and the ETS1 locus at 11q23----q24; ETS1 has been called hu-ets-1 or human c-ets-1. The tumor-associated chromosome 11 breakpoint is also different from those of leukemias with t(9;11) and t(4;11) translocations. Southern-blot analysis showed no rearrangement of ETS1 in these disorders in the region detected by our probe. ETS1 has also been mapped more precisely to 11q23.3----q24 by in situ hybridization to cells from an individual with an 11q23.3----qter deletion.

The beta-subunit of follicle-stimulating hormone is deleted in patients with aniridia and Wilms' tumour, allowing a further definition of the WAGR locus

One in 10,000 children develops Wilms' tumour, an embryonal malignancy of the kidney. Although most Wilms' tumours are sporadic, a genetic predisposition is associated with aniridia, genito-urinary malformations and mental retardation (the WAGR syndrome). Patients with this syndrome typically exhibit constitutional deletions involving band p13 of one chromosome 11 homologue. It is likely that these deletions overlap a cluster of separate but closely linked genes that control the development of the kidney, iris and urogenital tract (the WAGR complex). A discrete aniridia locus, in particular, has been defined within this chromosomal segment by a reciprocal translocation, transmitted through three generations, which interrupts 11p13. In addition, the specific loss of chromosome 11p alleles in sporadic Wilms' tumours has been demonstrated, suggesting that the WAGR complex includes a recessive oncogene, analogous to the retinoblastoma locus on chromosome 13. In WAGR patients, the inherited 11p deletion is thought to represent the first of two events required for the initiation of a Wilms' tumour, as suggested by Knudson from epidemiological data. We have now isolated the deleted chromosomes 11 from four WAGR patients in hamster-human somatic cell hybrids, and have tested genomic DNA from the hybrids with chromosome 11-specific probes. We show that 4 of 31 markers are deleted in at least one patient, but that of these markers, only the gene encoding the beta-subunit of follicle-stimulating hormone (FSHB) is deleted in all four patients. Our results demonstrate close physical linkage between FSHB and the WAGR locus, suggest a gene order for the four deleted markers and exclude other markers tested from this region. In hybrids prepared from a balanced translocation carrier with familial aniridia, the four markers segregate into proximal and distal groups. The translocation breakpoint, which identifies the position of the aniridia gene on 11p, is immediately proximal to FSHB, in the interval between FSHB and the catalase gene.

Exon/intron organization of the genes coding for the delta chains of the human and murine T-cell receptor/T3 complex

Genomic DNA clones containing the gene coding for the 20-kDa T3 glycoprotein of the T-cell receptor/T3 complex (T3-delta chain) of human and mouse were isolated and characterized. The human T3-delta gene is approximately equal to 4 kilobases (kb) long and contains five exons: a 151-base-pair (bp) exon containing the 5' untranslated and the coding sequences of the signal peptide, one exon of 219 bp, which contains most of the extracellular segment of the T3-delta chain, one 130-bp-long exon coding mainly for the transmembrane portion of the molecule, and two exons of 44 bp and 156 bp encoding the cytoplasmic domain and 3' untranslated region of the T3-delta chain, respectively. The murine T3-delta gene, which has a similar organization, contains 5 kb, because the first intron is approximately equal to 1 kb larger than in the human gene. Two major mRNA initiation sites within a small area approximately equal to 100 nucleotides 5' of the AUG codon were determined by S1 nuclease analysis and primer-extension studies. The remarkably high level of conservation of nucleotide sequences in this region suggests that this segment may be important for the regulation of T-cell-specific transcription of the T3-delta gene. The T3-delta gene does not contain the "TATA box" found in many eukaryotic promoters.

Localization of the human NCAM gene to band q23 of chromosome 11: the third gene coding for a cell interaction molecule mapped to the distal portion of the long arm of chromosome 11

cDNA clones containing sequences coding for the murine neural cell adhesion molecule (N-CAM) were used in Southern hybridizations on human genomic DNA and demonstrated approximately 90% homology between human and murine NCAM genes. In situ hybridization with one of these clones was performed on human metaphase chromosomes and allowed the localization of the human NCAM gene to band q23 of chromosome 11. The genes for two other cell surface molecules believed to be involved in cell-cell interactions, Thy-1 and the delta chain of the T3-T cell receptor complex, have recently been localized to the same region of chromosome 11 in man. Moreover, this region of the human chromosome 11 appears to be syntenic to a region of murine chromosome 9 that also contains the staggerer locus: staggerer mice show abnormal neurological features which may be related to abnormalities in the conversion of the embryonic to the adult forms of the N-CAM molecule.