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  • The human minor histocompatibility antigen 1 is a RhoGAP. 24086303

    The human minor Histocompatibility Antigen HMHA-1 is a major target of immune responses after allogeneic stem cell transplantation applied for the treatment of leukemia and solid tumors. The restriction of its expression to hematopoietic cells and many solid tumors raised questions regarding its cellular functions. Sequence analysis of the HMHA-1 encoding HMHA1 protein revealed the presence of a possible C-terminal RhoGTPase Activating Protein (GAP) domain and an N-terminal BAR domain. Rho-family GTPases, including Rac1, Cdc42, and RhoA are key regulators of the actin cytoskeleton and control cell spreading and migration. RhoGTPase activity is under tight control as aberrant signaling can lead to pathology, including inflammation and cancer. Whereas Guanine nucleotide Exchange Factors (GEFs) mediate the exchange of GDP for GTP resulting in RhoGTPase activation, GAPs catalyze the low intrinsic GTPase activity of active RhoGTPases, resulting in inactivation. Here we identify the HMHA1 protein as a novel RhoGAP. We show that HMHA1 constructs, lacking the N-terminal region, negatively regulate the actin cytoskeleton as well as cell spreading. Furthermore, we show that HMHA1 regulates RhoGTPase activity in vitro and in vivo. Finally, we demonstrate that the HMHA1 N-terminal BAR domain is auto-inhibitory as HMHA1 mutants lacking this region, but not full-length HMHA1, showed GAP activity towards RhoGTPases. In conclusion, this study shows that HMHA1 acts as a RhoGAP to regulate GTPase activity, cytoskeletal remodeling and cell spreading, which are crucial functions in normal hematopoietic and cancer cells.
    Tipo de documento:
    Referencia
    Referencia del producto:
    05-389
    Nombre del producto:
    Anti-Rac1 Antibody, clone 23A8

  • Influence of HLA-C expression level on HIV control. 23559252

    A variant upstream of human leukocyte antigen C (HLA-C) shows the most significant genome-wide effect on HIV control in European Americans and is also associated with the level of HLA-C expression. We characterized the differential cell surface expression levels of all common HLA-C allotypes and tested directly for effects of HLA-C expression on outcomes of HIV infection in 5243 individuals. Increasing HLA-C expression was associated with protection against multiple outcomes independently of individual HLA allelic effects in both African and European Americans, regardless of their distinct HLA-C frequencies and linkage relationships with HLA-B and HLA-A. Higher HLA-C expression was correlated with increased likelihood of cytotoxic T lymphocyte responses and frequency of viral escape mutation. In contrast, high HLA-C expression had a deleterious effect in Crohn's disease, suggesting a broader influence of HLA expression levels in human disease.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MABF233
    Nombre del producto:
    Anti-HLA-C Antibody, clone DT9

  • PRAME, a gene encoding an antigen recognized on a human melanoma by cytolytic T cells, is expressed in acute leukaemia cells. 9753074

    Gene PRAME was found to encode an antigen recognized on a human melanoma cell line by an autologous cytolytic T-lymphocyte clone. This gene is expressed at a high level in a very large fraction of tumours, such as melanomas, non-small-cell lung carcinomas, sarcomas, head and neck tumours and renal carcinomas. It is therefore a candidate for tumour immunotherapy even though some low expression is found in certain normal tissues. We tested by RT-PCR the expression of PRAME on more than 250 bone marrow or blood samples from patients with a haematological malignancy. Approximately 25% of the acute leukaemia samples were positive. Remarkably, all acute myeloblastic leukaemias that carried the chromosomal translocation t(8;21), which fuses the genes AML1 and ETO, expressed PRAME at a high level.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo

  • TLiSA1, a human T lineage-specific activation antigen involved in the differentiation of cytotoxic T lymphocytes and anomalous killer cells from their precursors. 2580933

    The characteristics of a novel T lineage-specific activation antigen, termed TLiSA1, are described. The antigen was detected with a mouse monoclonal antibody, LeoA1, that was raised against activated human T cells generated in mixed lymphocyte culture (MLC). The antigen became strongly expressed on T cells 48-72 h after stimulation with phytohemagglutinin, and retained expression on MLC-activated T cells after 10 d of culture. The antigen was absent from a range of human T, B, myeloid, fibroblast, and tumour cell lines, but was present on the surface of the interleukin 2 (IL-2)-dependent gibbon cell line MLA-144. Analysis of the antigen by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immunoprecipitates obtained from activated human T cells demonstrated a broad band in the region of 70 kD, whereas precipitates obtained from MLA-144 revealed a single narrow band of 95 kD. The molecule was expressed with a maximum density of 66,000 copies per cell on the surface of MLC-activated T cell blasts, as assessed by Scatchard analysis. TLiSA1 was distinguished from the IL-2 receptor bound by the anti-Tac monoclonal antibody by demonstrating that the antigens did not comodulate or coprecipitate, and by constructing an IL-2-independent human T X T hybrid that expressed the TLiSA1 but not the Tac antigen. MLC with B lymphoblasts was used to generate cytotoxic T lymphocytes (CTL) specific for the stimulating cell, and anomalous killer (AK) cells able to kill melanoma target cells. The presence of LeoA1 or F(ab')2 fragments of the antibody from the beginning of coculture did not affect proliferation in these cultures, but did inhibit the induction of both CTL and AK cells from their precursors. This inhibition of differentiation by LeoA1 was confirmed under conditions of limiting dilution, where it was shown that the antibody reduced the frequency of CTL produced, and greatly (fourfold) reduced the frequency of AK cells generated from their precursors. We discuss the possibility that human CTL may express a differentiation factor receptor that is distinct from the receptor for IL-2.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MABT398
    Nombre del producto:
    Anti-CD226/DNAM-1 Antibody, clone LeoA1 (Azide Free)

  • Transactivation of E2F-regulated genes by polyomavirus large T antigen: evidence for a two-step mechanism. 15572699

    Polyomavirus large T antigen transactivates a variety of genes whose products are involved in S phase induction. These genes are regulated by the E2F family of transcription factors, which are under the control of the pocket protein retinoblastoma protein and its relatives p130 and p107. The viral protein causes a dissociation of E2F-pocket protein complexes that results in transactivation of the genes. This reaction requires the N-terminal binding site for pocket proteins and the J domain that binds chaperones. We found earlier that a mutation of the zinc finger located within the C-terminal domain, a region assumed to function mainly in the replication of viral DNA, also interferes with transactivation. Here we show that binding of the histone acetyltransferase coactivator complex CBP/p300-PCAF to the C terminus correlates with the ability of large T antigen to transactivate genes. This interaction results in promoter-specific acetylation of histones. Inactive mutant proteins with changes within the C-terminal domain were nevertheless able to dissociate the E2F pocket protein complexes, indicating that this dissociation is a necessary but insufficient step in the T antigen-induced transactivation of genes. It has to be accompanied by a second step involving the T antigen-mediated recruitment of a histone acetyltransferase complex.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-599
    Nombre del producto:
    Anti-acetyl-Histone H3 Antibody

  • Multiple DNA damage signaling and repair pathways deregulated by simian virus 40 large T antigen. 20519379

    We demonstrated previously that expression of simian virus 40 (SV40) large T antigen (LT), without a viral origin, is sufficient to induce the hallmarks of a cellular DNA damage response (DDR), such as focal accumulation of gamma-H2AX and 53BP1, via Bub1 binding. Here we expand our characterization of LT effects on the DDR. Using comet assays, we demonstrate that LT induces overt DNA damage. The Fanconi anemia pathway, associated with replication stress, becomes activated, since FancD2 accumulates in foci, and monoubiquitinated FancD2 is detected on chromatin. LT also induces a distinct set of foci of the homologous recombination repair protein Rad51 that are colocalized with Nbs1 and PML. The FancD2 and Rad51 foci require neither Bub1 nor retinoblastoma protein binding. Strikingly, wild-type LT is localized on chromatin at, or near, the Rad51/PML foci, but the LT mutant in Bub1 binding is not localized there. SV40 infection was previously shown to trigger ATM activation, which facilitates viral replication. We demonstrate that productive infection also triggers ATR-dependent Chk1 activation and that Rad51 and FancD2 colocalize with LT in viral replication centers. Using small interfering RNA (siRNA)-mediated knockdown, we demonstrate that Rad51 and, to a lesser extent, FancD2 are required for efficient viral replication in vivo, suggesting that homologous recombination is important for high-level extrachromosomal replication. Taken together, the interplay of LT with the DDR is more complex than anticipated, with individual domains of LT being connected to different subcomponents of the DDR and repair machinery.
    Tipo de documento:
    Referencia
    Referencia del producto:
    05-530

  • IL-22 contributes to TGF-β1-mediated epithelial-mesenchymal transition in asthmatic bronchial epithelial cells. 24283210

    Allergic asthma is characterized by airway inflammation in response to antigen exposure, leading to airway remodeling and lung dysfunction. Epithelial-mesenchymal transition (EMT) may play a role in airway remodeling through the acquisition of a mesenchymal phenotype in airway epithelial cells. TGF-β1 is known to promote EMT; however, other cytokines expressed in severe asthma with extensive remodeling, such as IL-22, may also contribute to this process. In this study, we evaluated the contribution of IL-22 to EMT in primary bronchial epithelial cells from healthy and asthmatic subjects.Primary bronchial epithelial cells were isolated from healthy subjects, mild asthmatics and severe asthmatics (n=5 patients per group). The mRNA and protein expression of epithelial and mesenchymal cell markers and EMT-associated transcription factors was evaluated following stimulation with TGF-β1, IL-22 and TGF-β1+IL-22.Primary bronchial epithelial cells stimulated with TGF-β1 underwent EMT, demonstrated by decreased expression of epithelial markers (E-cadherin and MUC5AC) and increased expression of mesenchymal markers (N-cadherin and vimentin) and EMT-associated transcription factors. IL-22 alone had no effect on epithelial or mesenchymal gene expression. However, IL-22+TGF-β1 promoted the expression of some EMT transcription factors (Snail1 and Zeb1) and led to a more profound cadherin shift, but only in cells obtained from severe asthmatics.The impact of IL-22 on airway epithelial cells depends on the cytokine milieu and the clinical phenotype of the patient. Further studies are required to determine the molecular mechanism of IL-22 and TGF-β1 cooperativity in driving EMT in primary human bronchial epithelial cells.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB374
    Nombre del producto:
    Anti-Glyceraldehyde-3-Phosphate Dehydrogenase Antibody, clone 6C5

  • Isolation and culture of neurons and astrocytes from the mouse brain cortex. 21913093

    Many experimental animal models of human neurodegenerative diseases have been developed to understand the events leading toward neuronal dysfunction and death. However, definitive comprehension of the molecular and cellular mechanisms in these animal models is problematic because of the complexity of the intact nervous tissue. Primary neuronal cultures prepared from rodent nervous tissues represent a powerful tool not only to study the individual contribution of different cell types (such as neurons or glia) to disease progression, but also to investigate the role of neuron-glia interactions during development and pathogenesis of disease. Here, we describe a method to isolate and culture neurons and astrocytes from the mouse cerebral cortex, and we also present a practical application for transfection and subsequent immunofluorescence.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB3420
    Nombre del producto:
    Anti-Tau-1 Antibody, clone PC1C6

  • Modulation of the antigenic peptide transporter TAP by recombinant antibodies binding to the last five residues of TAP1. 17418234

    The transporter associated with antigen processing (TAP) plays a pivotal role in the major histocompatibility complex (MHC) class I mediated immune response against infected or malignantly transformed cells. It belongs to the ATP-binding cassette (ABC) superfamily and consists of TAP1 (ABCB2) and TAP2 (ABCB3), each of which possesses a transmembrane and a nucleotide-binding domain (NBD). Here we describe the generation of recombinant Fv and Fab antibody fragments to human TAP from a hybridoma cell line expressing the TAP1-specific monoclonal antibody mAb148.3. The epitope of the antibody was mapped to the very last five C-terminal amino acid residues of TAP1 on solid-supported peptide arrays. The recombinant antibody fragments were heterologously expressed in Escherichia coli and purified to homogeneity from periplasmic extracts by affinity chromatography. The monoclonal and recombinant antibodies bind with nanomolar affinity to the last five C-terminal amino acid residues of TAP1 as demonstrated by ELISA and surface plasmon resonance. Strikingly, the recombinant antibody fragments confer thermal stability to the heterodimeric TAP complex. At the same time TAP is arrested in a peptide transport incompetent conformation, although ATP and peptide binding to TAP are not affected. Based on our results we suggest that the C terminus of TAP1 modulates TAP function presumably as part of the dimer interface of the NBDs.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MABF125
    Nombre del producto:
    Anti-TAP1 Antibody, clone mAb 148.3

  • Interaction between host gastric Sialyl-Lewis X and H. pylori SabA enhances H. pylori density in patients lacking gastric Lewis B antigen. 16405531

    OBJECTIVES: We tested whether the interaction between host gastric Le(x) antigen and the SabA protein of H. pylori determined gastric colonization density. METHODS: A total of 145 H. pylori-infected patients were assessed for their bacterial density and gastric Le(b) and sialyl-Le(x) expression. Their corresponding H. pylori isolates were tested for babA2 and sabA genotype by PCR. The sabA-genopositive PCR products were sequenced to check for mutations affecting SabA expression. The BabA and SabA expressions of each isolate were confirmed by Western blotting. RESULTS: All 145 H. pylori isolates were babA2-genopositive and expressed BabA. There were 116 (80%) sabA-genopositive isolates, but only 45 (31%) of the isolates expressed SabA. Sequence of sabA-genopositive PCR products was achieved in 92 isolates, of which 60% had regular CT repeat-pairs and the other 40% had a unique deletion of the CT repeats. Neither the deletion nor the different CT repeat-pairs in the sabA region were totally correlated with SabA expression, defined by Western blotting. H. pylori density was higher in those expressing gastric sialyl-Le(x) antigen (which interacts with SabA) (p 0.001) only in those patients expressing weak or no gastric Le(b) antigen (which would interact with BabA), not in those with evident expression of gastric Le(b) antigen. CONCLUSIONS: In Taiwan, H. pylori isolates are 100% BabA-positive, but only 31% of them express SabA. The interaction between gastric sialyl-Le(x) and SabA of H. pylori determines the colonization density of patients expressing gastric Le(b) weakly or not at all.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB2096