Group-specific amplification of HLA-DQA1 revealed a number of genomic full-length sequences including the novel HLA alleles DQA1*01:10 and DQA1*01:11.

In this article, we describe a subgroup-specific amplification assay for HLA-DQA1 that encompasses the whole coding region and allows us to sequence full-length HLA-DQA1 genes. We introduce the novel alleles HLA-DQA1*01:10 and HLA-DQA1*01:11. Moreover, we were able to confirm the full-length genomic sequence data of the alleles HLA-DQA1*01:07, HLA-DQA1*03:01:01, HLA-DQA1*03:02, HLA-DQA1*04:01:02, HLA-DQA1*04:02, HLA-DQA1*05:03, HLA-DQA1*05:05:01:02 and HLA-DQA1*06:01:01. A complete genomic overview of all six HLA-DQA1 allele groups is now available from the submission of our data to the IMGT/HLA database. Because our approach facilitates the analysis of all HLA-DQA1 allele sequences, HLA-DQA1 may become the first HLA locus from which all subgroup members will be known in detail in the near future.

Nucleosomal structures of c-myc promoters with transcriptionally engaged RNA polymerase II.

Organization of DNA into chromatin has been shown to contribute to a repressed state of gene transcription. Disruption of nucleosomal structure is observed in response to gene induction, suggesting a model in which RNA polymerase II (pol II) is recruited to the promoter upon reorganization of nucleosomes. Here we show that induction of c-myc transcription correlates with the disruption of two nucleosomes in the upstream promoter region. This nucleosomal disruption, however, is not necessary for the binding of pol II to the promoter. Transcriptionally engaged pol II complexes can be detected when the upstream chromatin is in a more closed configuration. Thus, upstream chromatin opening is suggested to affect activation of promoter-bound pol II rather than entry of polymerases into the promoter. Interestingly, pol II complexes are detectable in both sense and antisense transcriptional directions, but only complexes in the sense direction respond to activation signals resulting in processive transcription.

A human immunodeficiency syndrome caused by mutations in CARMIL2.

Human T-cell function is dependent on T-cell antigen receptor (TCR) and co-signalling as evidenced by immunodeficiencies affecting TCR-dependent signalling pathways. Here, we show four human patients with EBV+ disseminated smooth muscle tumours that carry two homozygous loss-of-function mutations in the CARMIL2 (RLTPR) gene encoding the capping protein regulator and myosin 1 linker 2. These patients lack regulatory T cells without evidence of organ-specific autoimmunity, and have defective CD28 co-signalling associated with impaired T-cell activation, differentiation and function, as well as perturbed cytoskeletal organization associated with T-cell polarity and migration disorders. Human CARMIL2-deficiency is therefore an autosomal recessive primary immunodeficiency disorder associated with defective CD28-mediated TCR co-signalling and impaired cytoskeletal dynamics.

Two antisense promoters in the immunoglobulin mu-switch region drive expression of c-myc in the Burkitt's lymphoma cell line BL67.

In the Burkitt's lymphoma (BL) cell line BL67 the first exon of the c-myc gene is fused to the mu-switch region of the immunoglobulin heavy-chain gene (IgH). BL67 cells express IgH/c-myc hybrid RNAs which are initiated in the immunoglobulin locus, transcribed across the chromosomal breakpoint into the first exon of c-myc and spliced using the physiological splice donor and acceptor sites of the c-myc gene. We have isolated cDNAs of these hybrid RNAs and characterized the start points in the Ig heavy-chain gene. Two promoters were identified in the mu-switch region of BL67 cells which give rise to antisense transcription of the mu-gene. These promoters are also active in other BL cell lines, in B cells without Ig translocation and in a T-cell line. Both promoters co-localize with DNAase I-hypersensitive sites, HNF and HSW, in the mu-switch region. The structures of IgH/c-myc hybrid RNAs and of the corresponding promoters are described.

Absence of a paused transcription complex from the c-myc P2 promoter of the translocation chromosome in Burkitt's lymphoma cells: implication for the c-myc P1/P2 promoter shift.

We have shown recently that pausing of RNA polymerase II (pol II) at the transcription start site regulates expression from the P2 promoter of the proto-oncogene c-myc. RNAs initiated at the P2 promoter usually contribute > 80% to steady-state c-myc RNA levels in normal cells. In Burkitt's lymphoma (BL) cells c-myc is chromosomally translocated to an immunoglobulin (Ig) gene and preferentially transcribed from the upstream P1 promoter. We have studied the activity of c-myc promoters in two BL cell lines with high expression of P1 RNA. Kinetic nuclear run-on experiments show that the initiation rate at the c-myc P1 promoter in BL2 and BL60 cells is not increased compared with control BJAB cells, whereas the number of paused polymerases at the P2 promoter is greatly diminished. The translocation c-myc gene of BL60 cells was cloned and stably transfected into the BL cell line Raji. The transfected c-myc gene regained the ability to form a paused transcription complex at the c-myc P2 promoter. The data suggest that a paused polymerase at the c-myc P2 promoter impedes transcription from the upstream P1 promoter on a normal c-myc gene. The c-myc gene on the translocation chromosome in BL cells has lost the ability to retain pol II at the P2 promoter, probably by interaction with elements of the adjacent Ig gene locus.

The role of immunoglobulin kappa elements in c-myc activation.

Burkitt's lymphoma cells are characterized by chromosomal translocations involving the proto-oncogene c-myc on chromosome 8 and one of the immunoglobulin gene loci on chromosome 2, 14 or 22. The translocated c-myc allele is transcriptionally activated, shows a preferential usage of promoter P1 over P2 (promoter shift) and lacks the ability to retain the transcription complex at the P2 promoter. In order to define the elements of the immunoglobulin kappa gene involved in deregulation of c-myc in a t(2;8) translocation, we designed constructs consisting of c-myc and different parts of the immunoglobulin kappa gene locus. Chromatin analysis of these stably transfected constructs revealed DNase I hypersensitive sites within the c-myc 5' region characteristic for an actively transcribed c-myc gene and three sites within the immunoglobulin kappa locus corresponding to the matrix attachment region, the intron and 3' enhancers, respectively. These three regulatory elements were necessary and sufficient for maximal c-myc activation and formation of the promoter shift. Kinetic nuclear run on experiments were performed to study the distribution of transcription complexes on c-myc exon 1 on constructs with and without the immunoglobulin kappa regulatory elements. The absence of a pausing polymerase complex at the c-myc P2 promoter could be demonstrated for constructs consisting of c-myc and the two kappa enhancers. Therefore the two enhancers are sufficient to relief the elongational block at the P2 promoter, however, the matrix attachment region is additionally required for maximal c-myc activation observed in Burkitt's lymphoma cells.

c-myc expression is activated by the immunoglobulin kappa-enhancers from a distance of at least 30 kb but not by elements located within 50 kb of the unaltered c-myc locus in vivo.

50 kb of contiguous DNA sequences covering the human c-myc coding region and approximately 20 kb of flanking upstream and downstream sequences were cloned onto a prokaryotic F-factor derived plasmid, which also contains a selectable marker and the plasmid origin of DNA replication oriP of Epstein Barr virus (EBV). Since these plasmids replicate extrachromosomally after stable transfection into EBV-positive B-cell lines, the gene regulation of c-myc can be analysed independent from chromosomal integration positions. Despite the presence of all known c-myc regulatory elements on these constructs, expression from the stably transfected c-myc gene was barely detectable in either cell line. Hypermethylation of these plasmids could be excluded as a mechanism for the lack of gene expression. Insertion of the immunoglobulin kappa-intron and 3' enhancers, however, activated c-myc transcription, when placed adjacent to or separated from the c-myc promoters by as far as 30 kb. These results indicate that transcription of c-myc in vivo requires additional and still unidentified control elements located outside this 50 kb fragment, and experimentally demonstrate long range enhancer function in vivo.

Expression of truncated transcripts of the proto-oncogene c-fps/fes in human lymphoma and lymphoid leukemia cell lines.

The human c-fps/fes proto-oncogene is expressed as a transcript of about 3.0 kb in both normal and leukemic myeloid cells. We have detected truncated c-fps/fes transcripts of about 0.9 kb in a panel of human lymphoma and lymphoid leukemia cell lines, but not in normal untransformed hematopoietic cells. Analysis of the chromatin structure of the c-fps/fes gene revealed DNAase I-hypersensitive sites in the 5' region of the gene and in exon 16. The presence and absence of these sites correlates with the expression of the 3.0 kb and 0.9 kb c-fps/fes RNAs respectively. The truncated transcripts initiate at two distinct sites within exon 16 of the c-fps/fes gene. The genomic region 5' to the transcription initiation sites is G+C rich but does not contain typical promoter consensus sequences. Sequence analysis of a cDNA clone of the truncated c-fps/fes transcripts did not reveal any point mutation and the truncated transcripts are normally spliced using the regular splice donor and acceptor sites. A putative open reading frame encompasses the phosphotransfer motif and the autophosphorylation site of the fps/fes kinase domain. In vitro transcription/translation of a cDNA clone corresponding to the truncated c-fps/fes transcripts revealed a protein of 17 kDa. There are no translocations or rearrangements in or around the c-fps/fes gene in cell lines which express the truncated c-fps/fes transcripts. This alternative transcription of c-fps/fes may indicate a novel activation process of this proto-oncogene.

Deregulation of the proto-oncogene c-myc through t(8;22) translocation in Burkitt's lymphoma.

In Burkitt's lymphoma (BL) cells the proto-oncogene c-myc is juxtaposed to one of the immunoglobulin (Ig) loci on chromosomes 2, 14, or 22. The c-myc gene becomes transcriptionally activated as a consequence of the chromosomal translocation and shows preferential usage of promoter P1 over P2, a phenomenon referred to as promoter shift. In order to define the responsible regulatory elements within the Ig lambda locus, we studied the effect of the human Ig lambda enhancer (HuE lambda) on c-myc expression after stable transfection into BL cells. A 12 kb genomic fragment encompassing HuE lambda, but not HuE lambda alone, strongly activated c-myc expression and induced the promoter shift. To identify additional elements involved in c-myc deregulation, we mapped DNaseI hypersensitive sites within the 12 kb lambda fragment on the construct. Besides one hypersensitive site corresponding to HuE lambda, three additional sites were detected. Two of these elements displayed enhancer activity after transient transfection. The third element did not activate c-myc transcription, but was required for full c-myc activation and promoter shift. Deletion analyses of the c-myc promoter identified the immediate promoter region as sufficient for activation by the Ig lambda. locus, but also revealed that induction of the promoter shift requires additional upstream elements.

Popliteal venous aneurysm with pulmonary and paradoxical embolization.

A 31-year-old woman was admitted with recurrent pulmonary emboli. The patient subsequently developed right sided hemiplegia. A mobile left atrial mass attached to the interatrial septum was detected and paradoxical embolization was assumed to be the underlying cause of the cerebral event. Leg phlebography and B-mode ultrasonographic imaging showed that the most probable source of embolization was a right popliteal venous aneurysm containing thrombi adherent to the vein wall. The immediate treatment was restricted to full dose heparin therapy and supportive measures. Thirteen days after admission, the aneurysm was excised. Recovery was rapid and the patient was discharged for further rehabilitation with an only minimal neurological deficit 3 weeks after admission.

A novel HLA-DRB1 allele, HLA-DRB1*0465, was identified in a Hodgkin's lymphoma cell line.

The new human leucocyte antigen-DRB1*0465 allele was identified in the Hodgkin's lymphoma cell line KM-H2. This novel allele differs from the DRB1*0406 allele by a single nucleotide exchange at position 288 (211) (A-->T), which results in an arginine to tryptophan amino acid replacement at codon 90 in the new allele.

HLA-DQB1*0319, a novel HLA-DQB1 allele, shows strong haplotype association to HLA-DRB1*1102.

The new human leukocyte antigen-DQB1*0319 allele was identified in a prospective bone marrow donor by sequence-based typing. This novel allele differs from the DQB1*0301 allele at nucleotide position 554 (C-->T), which results in a Thr to Ile amino acid exchange. The new allele shows a strong association to DRB1*1102, suggesting that the haplotype DRB1*1102-DQB1*0319 is quite common.

Epstein-Barr virus vector-mediated gene transfer into human B cells: potential for antitumor vaccination.

The efficient gene transfer of immunostimulatory cytokines into autologous tumor cells or the transfer of tumor-associated antigens into professional antigen-presenting cells is a prerequisite for many immunotherapeutic approaches. In particular with B cells, the efficiency of gene uptake is one of the limiting factors in cell-based vaccine strategies, since normal and malignant human B cells are commonly refractory to transducing gene vectors. Due to its natural tropism for human B cells, Epstein-Barr virus (EBV), a human herpes virus, might be an option, which we wanted to explore. EBV efficiently infects human B cells and establishes a latent infection, while the viral genome is maintained extrachromosomally. Although these characteristics are attractive, EBV is an oncogenic virus. Here, we present a novel EBV-derived vector, which lacks three EBV genes including two viral oncogenes and an essential lytic gene, and encodes granulocyte-macrophage colony-stimulating factor (GM-CSF) as a cytokine of therapeutic interest. We could show that EBV vectors efficiently transduce different B-cell lines, primary resting B cells, and tumor cells of B-cell lineage. Vector-derived GM-CSF was expressed in sufficient amounts to support the maturation of dendritic cells and their presentation of model antigens to cognate T-cell clones in autologous settings and an allogeneic, HLA-matched assay. We conclude that the EBV vector system might offer an option for ex vivo manipulation of B cells and gene therapy of B-cell lymphomas.

Epstein-Barr virus BNRF1 protein allows efficient transfer from the endosomal compartment to the nucleus of primary B lymphocytes.

Epstein-Barr virus (EBV) is a tumor virus with marked B lymphotropism. After crossing the B-cell membrane, the virus enters cytoplasmic vesicles, where decapsidation takes place to allow transfer of the viral DNA to the cell nucleus. BNRF1 has been characterized as the EBV major tegument protein, but its precise function is unknown. We have constructed a viral mutant that lacks the BNRF1 gene and report here its in vitro phenotype. A recombinant virus devoid of BNRF1 (DeltaBNRF1) showed efficient DNA replication and production of mature viral particles. B cells infected with the DeltaBNRF1 mutant presented viral lytic antigens as efficiently as B cells infected with wild-type or BNRF1 trans-complemented DeltaBNRF1 viruses. Antigen presentation in B cells infected with either wild-type (EBV-wt) or DeltaBNRF1 virus was blocked by leupeptin addition, showing that both viruses reach the endosome/lysosome compartment. These data were confirmed by direct observation of the mutant virus in endosomes of infected B cells by electron microscopy. However, we observed a 20-fold reduction in the number of B cells expressing the nuclear protein EBNA2 after infection with a DeltaBNRF1 virus compared to wild-type infection. Likewise, DeltaBNRF1 viruses transformed primary B cells much less efficiently than EBV-wt or BNRF1 trans-complemented viruses. We conclude from these findings that BNRF1 plays an important role in viral transport from the endosomes to the nucleus.

The latent membrane protein 2 gene of Epstein-Barr virus is important for efficient B cell immortalization.

The viral latent membrane proteins 2 (LMP2) of Epstein-Barr virus (EBV) were analysed genetically to evaluate their role in B cell immortalization. LMP2 is transcribed as two differently spliced mRNAs which code for the LMP2A and -B proteins, also called terminal protein-1 and -2. LMP2A and -B are found in latently infected, growth-transformed B lymphocytes in vitro, in different human tumours, and in latently infected B cells in vivo. Two different approaches were used to generate EBV mutants in which the second, third and part of the fourth exon of the LMP2 gene were deleted by insertion of a marker gene. Initially, conventional homologous recombination in a Burkitt's lymphoma cell line (P3HR1) between the endogenous EBV genome and an introduced plasmid was used to generate EBV mutants. This experiment identified LMP2 as dispensable for B cell immortalization as has been reported. In a second approach, the same LMP2 mutant gene was analysed in the context of a mini-EBV plasmid. These are E. coli constructs that are sufficient when packaged into an EBV coat both to initiate and to maintain proliferation of infected B cells. In comparison with a fully competent mini-EBV, LMP2- mini-EBVs were found to be greatly reduced in their capacity to yield immortalized B cell clones. This finding confirmed the initially observed bias against LMP2- B cell clones, most of which were found to be coinfected with complementing P3HR1 virus. These results indicate that LMP2 contributes to the efficiency of B cell immortalization and that the LMP2s phenotype is auxiliary in nature.

Nucleosomal structure of active and inactive c-myc genes.

The nucleosomal structure of active and inactive c-myc genes has been analyzed in detail in undifferentiated and differentiated cells of the promyelocytic leukemia cell line HL60. The c-myc P2 promoter was never found in nucleosomal configuration, no matter whether c-myc was expressed or not. Differences in the nucleosomal structure, however, were found in the promoter upstream region proximal to a previously described DNase I-hypersensitive site I, at the P0 promoter, and at the P1 promoter and upstream thereof. In these regions nucleosomes were detected in differentiated but not undifferentiated HL60 cells. Similar patterns of nucleosomes as found for active and inactive c-myc genes in HL60 cells were found for active and inactive episomal c-myc genes in stably transfected B cell lines. In these cell lines three activation stages could be described for episomal c-myc constructs: (i) uninducible, (ii) inducible, and (iii) induced. Significant differences in the nucleosomal structure of c-myc were observed for the uninducible and inducible stages, but not for the inducible and induced stages.

Long-range chromatin analysis of the human MYC locus by pulsed-field gel electrophoresis.

The identification of cis-acting regulatory elements has been greatly facilitated by the perception that nonnucleosomal regions of chromatin, including sites where transacting factors are bound, are hypersensitive to cleavage by nucleases. Hence, mapping of DNaseI-hypersensitive sites (HSs) has become particularly valuable for the detection of transcriptional control elements. The utility of this technique, however, may be constrained by the huge size of some eukaryotic gene domains or by the nonavailability of genomic probes. Apparently, both of these drawbacks hold true for the human protooncogene MYC. To overcome these limitations, we investigated the feasibility of mapping DNaseI-HSs in large restriction fragments. By using MYC-amplified cell lines, we devised a simple protocol that allowed for the detection of DNaseI-HSs at a distance of several hundred kb. In an attempt to identify additional regulatory elements required for MYC expression, we used this method to establish the long-range chromatin structure of four MYC amplicons. This method has potential benefits and applications.

Identification of two enhancer elements downstream of the human c-myc gene.

Expression of the proto-oncogene c-myc is tightly regulated in vivo. Transcription of c-myc is assumed to be controlled by a number of positive and negative cis-acting control elements located upstream or within exon 1 and intron 1. However, these regulatory elements are not sufficient for c-myc expression after stable transfection or in transgenic mice. Transcription of c-myc in vivo thus requires additional control elements located outside the tested HindIII-EcoRI gene fragment. In order to identify these putative additional control elements, we mapped DNase I hypersensitive sites around the human c-myc gene in nine different tumor cell lines and in primary lymphocytes. Within the coding and 5' region of the gene, an almost identical pattern of DNase I hypersensitive sites was detected in the various cells. In contrast, chromatin analysis of the c-myc 3' region revealed a complex pattern of constitutive and tissue-specific DNase I hypersensitive sites. In enhancer trap experiments we identified two cis-acting control elements, both co-localizing with DNase I hypersensitive sites, that stimulated c-myc transcription after transient transfection in Raji or HeLa cells. Both regulatory elements exerted their enhancer activity in either orientation and regardless of their location within the plasmids. Both elements also conferred activation on a heterologous promoter. The association of these enhancers with DNase I hypersensitive sites, indicating their functional activity in vivo, make them potential candidates for the postulated regulatory control element(s) required for c-myc expression in vivo.

[Mechanical recanalization and local thrombolysis in a patient with fulminant pulmonary embolism and craniocerebral trauma]. / Mechanische Rekanalisation und lokale Thrombolyse bei einer Patientin mit fulminanter Lungenembolie und Schädeltrauma.

A 77-year-old female patient presenting with recurrent pulmonary embolism and shock had a severe craniocerebral trauma after collapsing at home 2 days before admission. Since systemic thrombolytic therapy appeared hazardous in this patient, percutaneous fragmentation and distal dispersion of the proximal pulmonary emboli was performed using a pigtail catheter. This procedure improved cardiac output immediately by 15%, whereas the mean pulmonary artery pressure dropped only slightly from 48 to 46 mmHg. Thereafter, a streptokinase infusion of 100,000 IU during 1 h was instituted through the pigtail catheter into the pulmonary artery. 12 hours after the treatment was started, cardiac output was raised by 70% and mean pulmonary artery pressure was decreased from 48 to 25 mmHg. 14 days after admission, control ventilation-perfusion scan showed a markedly improved pulmonary perfusion, and right heart catheterization revealed normal right heart pressures. The patient recovered rapidly and there was no evidence of recurrent pulmonary embolism 18 months later. This report demonstrates that a percutaneous catheter fragmentation of proximal pulmonary emboli combined with local intermediate-dose infusion of streptokinase may be a helpful therapeutic option in patients with massive pulmonary embolism in whom systemic thrombolytic therapy is contraindicated.