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Sample records for complex class i-related

  1. Elevation of soluble major histocompatibility complex class I related chain A protein in malignant and infectious diseases in Chinese patients

    PubMed Central

    2012-01-01

    Background Elevation of soluble major histocompatibility complex class I chain-related gene A (sMICA) products in serum has been linked to tissue/organ transplantation, autoimmune diseases and some malignant disorders. Cells infected by microbiological pathogens may release sMICA, whereas less is known whether and to what extent serum sMICA levels may change in infectious diseases. Methods The present study determined serum sMICA levels by enzyme-linked immunosorbent assay (ELISA) in a southern China population, including patients (n = 1041) suffering from several types of malignant and infectious diseases and healthy controls (n = 141). Results Relative to controls, serum sMICA elevation was significant in patients of hepatic cancer, and was approaching statistical significance in patients with lung, gastric and nasopharyngeal cancers. sMICA elevation was also associated with some bacterial (Enterobacteriaceae, Mycobacterium tuberculosis, non-fermenting Gram-negative bacteria and Gram-positive cocci), viral (hepatitis B and C) and the Microspironema pallidum infections. Conclusion Serum sMICA levels may be informative for the diagnosis of some malignant and infectious diseases. The results also indicate that microbiological infections should be considered as a potential confounding clinical condition causing serum sMICA elevation while using this test to evaluate the status of other disorders, such as cancers, host-graft response and autoimmune diseases. PMID:23181907

  2. Autoantibody Profiles in Collagen Disease Patients with Interstitial Lung Disease (ILD): Antibodies to Major Histocompatibility Complex Class I-Related Chain A (MICA) as Markers of ILD.

    PubMed

    Furukawa, Hiroshi; Oka, Shomi; Shimada, Kota; Masuo, Kiyoe; Nakajima, Fumiaki; Funano, Shunichi; Tanaka, Yuki; Komiya, Akiko; Fukui, Naoshi; Sawasaki, Tatsuya; Tadokoro, Kenji; Nose, Masato; Tsuchiya, Naoyuki; Tohma, Shigeto

    2015-01-01

    Interstitial lung disease (ILD) is frequently associated with collagen disease. It is then designated as collagen vascular disease-associated ILD (CVD-ILD), and influences patients' prognosis. The prognosis of acute-onset diffuse ILD (AoDILD) occurring in patients with collagen disease is quite poor. Here, we report our investigation of auto-antibody (Ab) profiles to determine whether they may be useful in diagnosing CVD-ILD or AoDILD in collagen disease. Auto-Ab profiles were analyzed using the Lambda Array Beads Multi-Analyte System, granulocyte immunofluorescence test, Proto-Array Human Protein Microarray, AlphaScreen assay, and glutathione S-transferase capture enzyme-linked immunosorbent assay in 34 patients with rheumatoid arthritis (RA) with or without CVD-ILD and in 15 patients with collagen disease with AoDILD. The average anti-major histocompatibility complex class I-related chain A (MICA) Ab levels were higher in RA patients with CVD-ILD than in those without (P = 0.0013). The ratio of the average anti-MICA Ab level to the average anti-human leukocyte antigen class I Ab level (ie, MICA/Class I) was significantly higher in RA patients with CVD-ILD compared with those without (P = 4.47 × 10(-5)). To the best of our knowledge, this is the first report of auto-Ab profiles in CVD-ILD. The MICA/Class I ratio could be a better marker for diagnosing CVD-ILD than KL-6 (Krebs von den lungen-6). PMID:26327779

  3. Autoantibody Profiles in Collagen Disease Patients with Interstitial Lung Disease (ILD): Antibodies to Major Histocompatibility Complex Class I-Related Chain A (MICA) as Markers of ILD

    PubMed Central

    Furukawa, Hiroshi; Oka, Shomi; Shimada, Kota; Masuo, Kiyoe; Nakajima, Fumiaki; Funano, Shunichi; Tanaka, Yuki; Komiya, Akiko; Fukui, Naoshi; Sawasaki, Tatsuya; Tadokoro, Kenji; Nose, Masato; Tsuchiya, Naoyuki; Tohma, Shigeto

    2015-01-01

    Interstitial lung disease (ILD) is frequently associated with collagen disease. It is then designated as collagen vascular disease-associated ILD (CVD-ILD), and influences patients’ prognosis. The prognosis of acute-onset diffuse ILD (AoDILD) occurring in patients with collagen disease is quite poor. Here, we report our investigation of auto-antibody (Ab) profiles to determine whether they may be useful in diagnosing CVD-ILD or AoDILD in collagen disease. Auto-Ab profiles were analyzed using the Lambda Array Beads Multi-Analyte System, granulocyte immunofluorescence test, Proto-Array Human Protein Microarray, AlphaScreen assay, and glutathione S-transferase capture enzyme-linked immunosorbent assay in 34 patients with rheumatoid arthritis (RA) with or without CVD-ILD and in 15 patients with collagen disease with AoDILD. The average anti-major histocompatibility complex class I-related chain A (MICA) Ab levels were higher in RA patients with CVD-ILD than in those without (P = 0.0013). The ratio of the average anti-MICA Ab level to the average anti-human leukocyte antigen class I Ab level (ie, MICA/Class I) was significantly higher in RA patients with CVD-ILD compared with those without (P = 4.47 × 10−5). To the best of our knowledge, this is the first report of auto-Ab profiles in CVD-ILD. The MICA/Class I ratio could be a better marker for diagnosing CVD-ILD than KL-6 (Krebs von den lungen-6). PMID:26327779

  4. Role of major histocompatibility complex class I-related molecules A*A5·1 allele in ulcerative colitis in Chinese patients

    PubMed Central

    Lü, Min; Xia, Bing; Ge, Liuqing; Li, Yi; Zhao, Jie; Chen, Fan; Zhou, Feng; Zhang, Xiaolian; Tan, Jinquan

    2009-01-01

    The major histocompatibility complex (MHC) class I-related molecules A (MICA) is a stress-inducible cell surface antigen that is recognized by intestinal epithelial Vδ1 γδ T cells, natural killer (NK) cells and CD8+ T cells with NKG2D receptor participating in the immunological reaction in the intestinal mucosa. The present study aimed to investigate the functions of the MICA*A5.1 allele in the development of ulcerative colitis (UC) in the Chinese population. The microsatellite polymorphisms of MICA were genotyped in 124 unrelated Chinese patients with UC and 172 ethnically matched healthy controls using a semiautomatic fluorescently labelled polymerase chain reaction. MICA*A5.1-expressing Raji cells were generated by gene transfection. Cytotoxicity of NK cells to Raji cells expressing different MICA molecules was detected using the lactate dehydrogenase method. Soluble MICA in the culture supernatant was detected by enzyme-linked immunosorbent assay. The frequency of MICA*A5.1 was significantly higher in UC patients compared with the healthy controls (29·0% versus 17·4%, P= 0·001, corrected P= 0·005, OR = 1·936, 95% CI 1·310–2·863) and the frequency of a MICA*A5.1/A5.1 homozygous genotype was increased in UC patients (18·5% versus 7% in healthy controls, P= 0·0032, corrected P= 0·048, OR = 3·036, 95% CI 1·447–6·372). Raji cells with MICA*A5.1 expression produced more soluble MICA (t = 5·75, P < 0·01) than Raji cells with full-length MICA expression in culture supernatant. Raji cells with MICA*A5.1 expression were more resistant to killing by NK cells than Raji cells with full-length MICA expression. The MICA*A5.1 allele and MICA*A5.1/A5.1 genotype are significantly associated with Chinese UC patients in central China. MICA*A5.1 may play a role in the development of UC by producing more soluble MICA and resistance to NK cells. PMID:19016911

  5. MHC class I-related molecule, MR1, and mucosal-associated invariant T cells.

    PubMed

    Franciszkiewicz, Katarzyna; Salou, Marion; Legoux, Francois; Zhou, Qian; Cui, Yue; Bessoles, Stéphanie; Lantz, Olivier

    2016-07-01

    The MHC-related 1, MR1, molecule presents a new class of microbial antigens (derivatives of the riboflavin [Vitamin B2] biosynthesis pathway) to mucosal-associated invariant T (MAIT) cells. This raises many questions regarding antigens loading and intracellular trafficking of the MR1/ligand complexes. The MR1/MAIT field is also important because MAIT cells are very abundant in humans and their frequency is modified in many infectious and non-infectious diseases. Both MR1 and the invariant TCRα chain expressed by MAIT cells are strikingly conserved among species, indicating important functions. Riboflavin is synthesized by plants and most bacteria and yeasts but not animals, and its precursor derivatives activating MAIT cells are short-lived unless bound to MR1. The recognition of MR1 loaded with these compounds is therefore an exquisite manner to detect invasive bacteria. Herein, we provide an historical perspective of the field before describing the main characteristics of MR1, its ligands, and the few available data regarding its cellular biology. We then summarize the current knowledge of MAIT cell differentiation and discuss the definition of MAIT cells in comparison to related subsets. Finally, we describe the phenotype and effector activities of MAIT cells. PMID:27319347

  6. Expression and purification of human MHC class I-related chain molecule B-α1 domain.

    PubMed

    Wang, Shufen; Xiang, Zemin; Wang, Ya; Xu, Huanhuan; Zhang, Dengyang; Wang, Xuanjun; Sheng, Jun

    2016-07-01

    Major histocompatibility complex (MHC) class I-related chain A/B (MICA/B) is a type of stress-induced molecule that plays an important role in tumor surveillance. MICA/B shares a similar structure with MHC class I molecules, but MICA/B contains a closed cleft, not an open one, in its N-terminal alpha1 domain. The alpha 1 domain was believed to have no roles in antigen presentation, because the closed cleft provides limited space for binding with known molecules, and the cleft of MICA/B have been reported no known functions. To study the possible function of the cleft located in human MICA/B's alpha 1 domain, we attempted to express the human MICB-α1 (hMICB-α1) domain allele protein, which is approximately 20.5 kDa, by utilizing an Escherichia coli (E. coli) secretory pathway. Protein expression was accomplished through the phosphate-limited inducible promoter. After purification using ammonium sulfate precipitation, phenyl hydrophobic Sepharose, SP Sepharose and HisTrap affinity Sepharose, recombinant human MICB-α1 (rhMICB-α1) was obtained with 94.3% purity. The binding capacity of rhMICB-α1 with natural killer group 2, member D (NKG2D) was evaluated in vitro. The results demonstrated that rhMICB-α1 can be prepared through the E. coli secretory pathway. Purified rhMICB-α1 protein was able to functionally bind with NKG2D. This method can be further used to obtain functionally active rhMICB-α1 protein, which can served as the basis for further studies of the possible function of the MICB cleft. PMID:27036081

  7. Identification and characterization of a novel splicing variant of the MHC classI-related Neonatal Fc receptor for IgG

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The neonatal Fc receptor for IgG (FcRn), a MHC class I-related molecule, functions to transport maternal IgG into the fetus or newborn via placenta and/or intestine and protects IgG from catabolism. The mRNAs of several MHC class I-related molecules have multiple splicing variants. In the course of ...

  8. Clonal expansion of double-positive intraepithelial lymphocytes by MHC class I-related chain A expressed in mouse small intestinal epithelium.

    PubMed

    Park, Eun Jeong; Takahashi, Ichiro; Ikeda, Junko; Kawahara, Kazuko; Okamoto, Tetsuji; Kweon, Mi-Na; Fukuyama, Satoshi; Groh, Veronika; Spies, Thomas; Obata, Yuichi; Miyazaki, Jun-Ichi; Kiyono, Hiroshi

    2003-10-15

    Expression of a distant homologue MHC class I molecule, MHC class I-related chain A (MICA), has been found to be stress inducible and limited to the intestinal epithelium. This nonclassical MHC molecule is associated with various carcinomas in humans. To understand the biological consequences of MICA expression in the gut, we generated transgenic (Tg) mice (T3(b)-MICA Tg) under the control of the T3(b) promoter. The T3(b)-MICA Tg mice expressed MICA selectively in the intestine and had an increased number of TCRalphabeta CD4CD8alphaalpha, double-positive (DP) intraepithelial lymphocytes (IELs) in the small bowel. These MICA-expanded DP IELs exhibited a bias to Vbeta8.2 and overlapped motifs of the complementarity-determining region 3 region among various Tg mice. Hence, the overexpression of MICA resulted in a clonal expansion of DP IELs. Studies in model of inflammatory bowel disease showed that transgenic MICA was able to attenuate the acute colitis induced by dextran sodium sulfate administration. Therefore, this unique in vivo model will enable investigation of possible influences of stress-inducible MICA on the gut immune surveillance. PMID:14530335

  9. MHC Class I-Related Neonatal Fc Receptor for IgG Is Functionally Expressed in Monocytes, Intestinal Macrophages, and Dendritic Cells1

    PubMed Central

    Zhu, Xiaoping; Meng, Gang; Dickinson, Bonny L.; Li, Xiaotong; Mizoguchi, Emiko; Miao, Lili; Wang, Yuansheng; Robert, Caroline; Wu, Benyan; Smith, Phillip D.; Lencer, Wayne I.; Blumberg, Richard S.

    2010-01-01

    The neonatal Fc receptor (FcRn) for IgG, an MHC class I-related molecule, functions to transport IgG across polarized epithelial cells and protect IgG from degradation. However, little is known about whether FcRn is functionally expressed in immune cells. We show here that FcRn mRNA was identifiable in human monocytes, macrophages, and dendritic cells. FcRn heavy chain was detectable as a 45-kDa protein in monocytic U937 and THP-1 cells and in purified human intestinal macrophages, peripheral blood monocytes, and dendritic cells by Western blot analysis. FcRn colocalized in vivo with macrosialin (CD68) and Ncl-Macro, two macrophage markers, in the lamina propria of human small intestine. The heavy chain of FcRn was associated with the β2-microglobulin (β2m) light chain in U937 and THP-1 cells. FcRn bound human IgG at pH 6.0, but not at pH 7.5. This binding could be inhibited by human IgG Fc, but not Fab. FcRn could be detected on the cell surface of activated, but not resting, THP-1 cells. Furthermore, FcRn was uniformly present intracellularly in all blood monocytes and intestinal macrophages. FcRn was detectable on the cell surface of a significant fraction of monocytes at lower levels and on a small subset of tissue macrophages that expressed high levels of FcRn on the cell surface. These data show that FcRn is functionally expressed and its cellular distribution is regulated in monocytes, macrophages, and dendritic cells, suggesting that it may confer novel IgG binding functions upon these cell types relative to typical FcγRs: FcγRI, FcγRII, and FcγRIII. PMID:11207281

  10. UL16-binding proteins, novel MHC class I-related proteins, bind to NKG2D and activate multiple signaling pathways in primary NK cells.

    PubMed

    Sutherland, Claire L; Chalupny, N Jan; Schooley, Kenneth; VandenBos, Tim; Kubin, Marek; Cosman, David

    2002-01-15

    The UL16-binding proteins (ULBPs) are a novel family of MHC class I-related molecules that were identified as targets of the human CMV glycoprotein, UL16. We have previously shown that ULBP expression renders a relatively resistant target cell sensitive to NK cytotoxicity, presumably by engaging NKG2D, an activating receptor expressed by NK and other immune effector cells. In this study we show that NKG2D is the ULBP counterstructure on primary NK cells and that its expression is up-regulated by IL-15 stimulation. Soluble forms of ULBPs induce marked protein tyrosine phosphorylation, and activation of the Janus kinase 2, STAT5, extracellular signal-regulated kinase, mitogen-activated protein kinase, and phosphatidylinositol 3-kinase (PI 3-kinase)/Akt signal transduction pathways. ULBP-induced activation of Akt and extracellular signal-regulated kinase and ULBP-induced IFN-gamma production are blocked by inhibitors of PI 3-kinase, consistent with the known binding of PI 3-kinase to DAP10, the membrane-bound signal-transducing subunit of the NKG2D receptor. While all three ULBPs activate the same signaling pathways, ULBP3 was found to bind weakly and to induce the weakest signal. In summary, we have shown that NKG2D is the ULBP counterstructure on primary NK cells and for the first time have identified signaling pathways that are activated by NKG2D ligands. These results increase our understanding of the mechanisms by which NKG2D activates immune effector cells and may have implications for immune surveillance against pathogens and tumors. PMID:11777960

  11. On the structure of valiant's complexity classes

    NASA Astrophysics Data System (ADS)

    Bürgisser, Peter

    In [25,27] Valiant developed an algebraic analogue of the theory of NP-completeness for computations with polynomials over a field. We further develop this theory in the spirit of structural complexity and obtain analogues of well-known results by Baker, Gill, and Solovay [1], Ladner [18], and Schöning [23,24].

  12. Evolution of major histocompatibility complex class I and class II genes in the brown bear

    PubMed Central

    2012-01-01

    Background Major histocompatibility complex (MHC) proteins constitute an essential component of the vertebrate immune response, and are coded by the most polymorphic of the vertebrate genes. Here, we investigated sequence variation and evolution of MHC class I and class II DRB, DQA and DQB genes in the brown bear Ursus arctos to characterise the level of polymorphism, estimate the strength of positive selection acting on them, and assess the extent of gene orthology and trans-species polymorphism in Ursidae. Results We found 37 MHC class I, 16 MHC class II DRB, four DQB and two DQA alleles. We confirmed the expression of several loci: three MHC class I, two DRB, two DQB and one DQA. MHC class I also contained two clusters of non-expressed sequences. MHC class I and DRB allele frequencies differed between northern and southern populations of the Scandinavian brown bear. The rate of nonsynonymous substitutions (dN) exceeded the rate of synonymous substitutions (dS) at putative antigen binding sites of DRB and DQB loci and, marginally significantly, at MHC class I loci. Models of codon evolution supported positive selection at DRB and MHC class I loci. Both MHC class I and MHC class II sequences showed orthology to gene clusters found in the giant panda Ailuropoda melanoleuca. Conclusions Historical positive selection has acted on MHC class I, class II DRB and DQB, but not on the DQA locus. The signal of historical positive selection on the DRB locus was particularly strong, which may be a general feature of caniforms. The presence of MHC class I pseudogenes may indicate faster gene turnover in this class through the birth-and-death process. South–north population structure at MHC loci probably reflects origin of the populations from separate glacial refugia. PMID:23031405

  13. Liquid class predictor for liquid handling of complex mixtures

    DOEpatents

    Seglke, Brent W.; Lekin, Timothy P.

    2008-12-09

    A method of establishing liquid classes of complex mixtures for liquid handling equipment. The mixtures are composed of components and the equipment has equipment parameters. The first step comprises preparing a response curve for the components. The next step comprises using the response curve to prepare a response indicator for the mixtures. The next step comprises deriving a model that relates the components and the mixtures to establish the liquid classes.

  14. "Distribution and functional identification of complex class 1 integrons".

    PubMed

    Quiroga, María Paula; Arduino, Sonia Marina; Merkier, Andrea Karina; Quiroga, Cecilia; Petroni, Alejandro; Roy, Paul H; Centrón, Daniela

    2013-10-01

    The emergence of extended-spectrum β-lactamases and plasmid-mediated resistance to quinolones has been previously found to be associated with the dissemination of complex class 1 integrons in Argentina. In this study, we analyzed their distribution through time and evaluated the functionality of the Orf513 protein, which is the putative recombinase of the ISCR1 mobile element. We investigated the presence of the orf513, blaCTX-M-2, dfrA3b, qnrB10 and blaDHA-1 genes by PCR and DNA sequencing as well as their linkage to class 1 integrons in 451 non-epidemiologically related nosocomial strains resistant to at least one expanded-spectrum cephalosporin and to one aminoglycoside, isolated between 1989 and 2010 from 7 hospitals from Buenos Aires City. The epidemiology of complex class 1 integrons was found to be notably different among fermenting (94/171) and non-fermenting clinical bacilli isolates (1/280). The ISCR1::qnrB10 positive isolates were found since 1993, confirming its presence in clinical isolates more than a decade before its first description. As expected, In35::ISCR1::blaCTX-M-2 was the most common complex class 1 integron among Enterobacteriaceae isolates, particularly in Proteus mirabilis. Experimental analysis corroborated the activity of the Orf513 protein, which was found to bind specific DNA sequences containing the previously suggested oriIS region. These findings showed the high dispersion and maintenance of complex class 1 integrons across time in our nosocomial isolates. The contribution of the ISCR1 mobile element to multidrug resistant phenotypes is significant due to its sustained association to class 1 integrons. PMID:23838285

  15. The complexity of class polynomial computation via floating point approximations

    NASA Astrophysics Data System (ADS)

    Enge, Andreas

    2009-06-01

    We analyse the complexity of computing class polynomials, that are an important ingredient for CM constructions of elliptic curves, via complex floating point approximations of their roots. The heart of the algorithm is the evaluation of modular functions in several arguments. The fastest one of the presented approaches uses a technique devised by Dupont to evaluate modular functions by Newton iterations on an expression involving the arithmetic-geometric mean. Under the heuristic assumption, justified by experiments, that the correctness of the result is not perturbed by rounding errors, the algorithm runs in time O left( sqrt {\\vert D\\vert} log^3 \\vert D\\vert M left( sq... ...arepsilon} \\vert D\\vert right) subseteq O left( h^{2 + \\varepsilon} right) for any \\varepsilon > 0 , where D is the CM discriminant, h is the degree of the class polynomial and M (n) is the time needed to multiply two n -bit numbers. Up to logarithmic factors, this running time matches the size of the constructed polynomials. The estimate also relies on a new result concerning the complexity of enumerating the class group of an imaginary quadratic order and on a rigorously proven upper bound for the height of class polynomials.

  16. Caenorhabditis elegans expressing the Saccharomyces cerevisiae NADH alternative dehydrogenase Ndi1p, as a tool to identify new genes involved in complex I related diseases

    PubMed Central

    Cossard, Raynald; Esposito, Michela; Sellem, Carole H.; Pitayu, Laras; Vasnier, Christelle; Delahodde, Agnès; Dassa, Emmanuel P.

    2015-01-01

    Isolated complex I deficiencies are one of the most commonly observed biochemical features in patients suffering from mitochondrial disorders. In the majority of these clinical cases the molecular bases of the diseases remain unknown suggesting the involvement of unidentified factors that are critical for complex I function. The Saccharomyces cerevisiae NDI1 gene, encoding the mitochondrial internal NADH dehydrogenase was previously shown to complement a complex I deficient strain in Caenorhabditis elegans with notable improvements in reproduction and whole organism respiration. These features indicate that Ndi1p can functionally integrate the respiratory chain, allowing complex I deficiency complementation. Taking into account the Ndi1p ability to bypass complex I, we evaluate the possibility to extend the range of defects/mutations causing complex I deficiencies that can be alleviated by NDI1 expression. We report here that NDI1 expressing animals unexpectedly exhibit a slightly shortened lifespan, a reduction in the progeny, and a depletion of the mitochondrial genome. However, Ndi1p is expressed and targeted to the mitochondria as a functional protein that confers rotenone resistance to those animals without affecting their respiration rate and ATP content. We show that the severe embryonic lethality level caused by the RNAi knockdowns of complex I structural subunit encoding genes (e.g., NDUFV1, NDUFS1, NDUFS6, NDUFS8, or GRIM-19 human orthologs) in wild type animals is significantly reduced in the Ndi1p expressing worm. All together these results open up the perspective to identify new genes involved in complex I function, assembly, or regulation by screening an RNAi library of genes leading to embryonic lethality that should be rescued by NDI1 expression. PMID:26124772

  17. Activation of the JAK/STAT-1 Signaling Pathway by IFN-γ Can Down-Regulate Functional Expression of the MHC Class I-Related Neonatal Fc Receptor for IgG1

    PubMed Central

    Liu, Xindong; Ye, Lilin; Bai, Yu; Mojidi, Habi; Simister, Neil E.; Zhu, Xiaoping

    2009-01-01

    Expression of many MHC genes is enhanced at the transcriptional or posttranscriptional level following exposure to the cytokine IFN-γ. However, in this study we found that IFN-γ down-regulated the constitutive expression of the neonatal Fc receptor (FcRn), an MHC class I-related molecule that functions to transport maternal IgG and protect IgG and albumin from degradation. Epithelial cell, macrophage-like THP-1 cell, and freshly isolated human PBMC exposure to IFN-γ resulted in a significant decrease of FcRn expression as assessed by real-time RT-PCR and Western blotting. The down-regulation of FcRn was not caused by apoptosis or the instability of FcRn mRNA. Chromatin immunoprecipitation and gel mobility shift assays showed that STAT-1 bound to an IFN-γ activation site in the human FcRn promoter region. Luciferase expression from an FcRn promoter-luciferase reporter gene construct was not altered in JAK1- and STAT-1-deficient cells following exposure to IFN-γ, whereas expression of JAK1 or STAT-1 protein restored the IFN-γ inhibitory effect on luciferase activity. The repressive effect of IFN-γ on the FcRn promoter was selectively reversed or blocked by mutations of the core nucleotides in the IFN-γ activation site sequence and by over-expression of the STAT-1 inhibitor PIAS1 or the dominant negative phospho-STAT-1 mutations at Tyr-701 and/or Ser-727 residues. Furthermore, STAT-1 might down-regulate FcRn transcription through sequestering the transcriptional coactivator CREB binding protein/p300. Functionally, IFN-γ stimulation dampened bidirectional transport of IgG across a polarized Calu-3 lung epithelial monolayer. Taken together, our results indicate that the JAK/STAT-1 signaling pathway was necessary and sufficient to mediate the down-regulation of FcRn gene expression by IFN-γ. PMID:18566411

  18. Regulation of major histocompatibility complex class II genes

    PubMed Central

    Choi, Nancy M.; Majumder, Parimal; Boss, Jeremy M.

    2010-01-01

    Summary The major histocompatibility complex class II (MHC-II) genes are regulated at the level of transcription. Recent studies have shown that chromatin modification is critical for efficient transcription of these genes, and a number of chromatin modifying complexes recruited to MHC-II genes have been described. The MHC-II genes are segregated from each other by a series of chromatin elements, termed MHC-II insulators. Interactions between MHC-insulators and the promoters of MHC-II genes are mediated by the insulator factor CCCTC-binding protein and are critical for efficient expression. This regulatory mechanism provides a novel view of how the entire MHC-II locus is assembled architecturally and can be coordinately controlled. PMID:20970972

  19. Receptor complexes for each of the Class 3 Semaphorins.

    PubMed

    Sharma, Anil; Verhaagen, Joost; Harvey, Alan R

    2012-01-01

    The Class 3 Semaphorins (Sema3s) are a sub-family of proteins whose known biological roles are varied and growing. The mechanism of action of the Sema3s requires binding to transmembrane receptors that comprise heteromeric complexes of Neuropilins, Plexins and cell adhesion molecules (CAMs). However, knowledge of the receptor components of the Sema3s remains incomplete, and there may be receptor components which are as yet undiscovered. The receptor complexes of the Sema3s share receptor components with each other, and it is the specific combination of these components within a heteromeric complex that is thought to give rise to selective binding and signalling for individual Sema3s. This crosstalk makes it experimentally difficult to define a single holoreceptor for each Sema3. Furthermore, the receptor composition for a given Sema3 may differ between cell types, and change as a function of developmental state or pathological situation. Nevertheless, there are at least some known differences in the constitutive structure of the receptors for the Sema3s. For example in neural cells, Sema3a and Sema3f signal through different Neuropilins (Nrp1 and Nrp2 respectively) and L1cam only appears important for Sema3a signaling, while Nrcam forms a complex with Nrp2. Further complexity arises from crosstalk of other families of ligands (e.g., VEGF) with Sema3 receptor components. Thus the Sema3s, which have been shown as antagonists for each other, can also act as antagonists for other families of molecules. This review compiles experimental evidence describing the receptor components for the Sema3s, detailing the current state of knowledge of which components are important for signaling of each Sema3 before going on to consider possible future directions for the field. PMID:22783168

  20. Bidirectional selection between two classes in complex social networks

    NASA Astrophysics Data System (ADS)

    Zhou, Bin; He, Zhe; Jiang, Luo-Luo; Wang, Nian-Xin; Wang, Bing-Hong

    2014-12-01

    The bidirectional selection between two classes widely emerges in various social lives, such as commercial trading and mate choosing. Until now, the discussions on bidirectional selection in structured human society are quite limited. We demonstrated theoretically that the rate of successfully matching is affected greatly by individuals' neighborhoods in social networks, regardless of the type of networks. Furthermore, it is found that the high average degree of networks contributes to increasing rates of successful matches. The matching performance in different types of networks has been quantitatively investigated, revealing that the small-world networks reinforces the matching rate more than scale-free networks at given average degree. In addition, our analysis is consistent with the modeling result, which provides the theoretical understanding of underlying mechanisms of matching in complex networks.

  1. Bidirectional selection between two classes in complex social networks

    PubMed Central

    Zhou, Bin; He, Zhe; Jiang, Luo-Luo; Wang, Nian-Xin; Wang, Bing-Hong

    2014-01-01

    The bidirectional selection between two classes widely emerges in various social lives, such as commercial trading and mate choosing. Until now, the discussions on bidirectional selection in structured human society are quite limited. We demonstrated theoretically that the rate of successfully matching is affected greatly by individuals' neighborhoods in social networks, regardless of the type of networks. Furthermore, it is found that the high average degree of networks contributes to increasing rates of successful matches. The matching performance in different types of networks has been quantitatively investigated, revealing that the small-world networks reinforces the matching rate more than scale-free networks at given average degree. In addition, our analysis is consistent with the modeling result, which provides the theoretical understanding of underlying mechanisms of matching in complex networks. PMID:25524835

  2. Polyelectrolyte-Surfactant Complexes: A New Class of Organogelators

    NASA Astrophysics Data System (ADS)

    Cavicchi, Kevin; Liu, Yuqing; Guzman, Gustavo

    2011-03-01

    Polyelectrolyte-surfactant complexes (PE-SURFs) are a class of polymers generated by neutralizing a polyelectrolyte with an oppositely charged surfactant. It has been found that PE-SURFs composed of polystyrene sulfonate and long chain alkyl dimethyl amines act as good organogelators for a range of hydrophobic, organic solvents. Thermo-reversible organogels are formed by heating and cooling PE-SURF/solvent solutions. The gel transition temperature is influenced by the degree of polymerization, the length of the alkyl side-chain, the solubility parameter of the solvent, and the concentration of the gelator. Freeze-drying and scanning electron microscopy characterization of the resultant xerogels shows the formation of rod- and plate-like network morphologies depending on the system parameters. This behavior is consistent with gelation driven by the self-assembly of the amphiphilic PE-SURFs into micellar networks.

  3. Clinical significance of tumor expression of major histocompatibility complex class I-related chains A and B (MICA/B) in gastric cancer patients.

    PubMed

    Ribeiro, Carolina Hager; Kramm, Karina; Gálvez-Jirón, Felipe; Pola, Víctor; Bustamante, Marco; Contreras, Hector R; Sabag, Andrea; Garrido-Tapia, Macarena; Hernández, Carolina J; Zúñiga, Roberto; Collazo, Norberto; Sotelo, Pablo Hernán; Morales, Camila; Mercado, Luis; Catalán, Diego; Aguillón, Juan Carlos; Molina, María Carmen

    2016-03-01

    Gastric cancer (GC) is the third most common cause of cancer death worldwide. Natural killer cells play an important role in the immune defense against transformed cells. They express the activating receptor NKG2D, whose ligands belong to the MIC and ULBP/RAET family. Although it is well established that these ligands are generally expressed in tumors, the association between their expression in the tumor and gastric mucosa and clinical parameters and prognosis of GC remains to be addressed. In the present study, MICA and MICB expression was analyzed, by flow cytometry, in 23 and 20 pairs of gastric tumor and adjacent non-neoplasic gastric mucosa, respectively. Additionally, ligands expression in 13 tumors and 7 gastric mucosa samples from GC patients were evaluated by immunohistochemistry. The mRNA levels of MICA in 9 pairs of tumor and mucosa were determined by quantitative PCR. Data were associated with the clinicopathological characteristics and the patient outcome. MICA expression was observed in 57% of tumors (13/23) and 44% of mucosal samples (10/23), while MICB was detected in 50% of tumors (10/20) and 45% of mucosal tissues (9/20). At the protein level, ligand expression was significantly higher in the tumor than in the gastric mucosa. MICA mRNA levels were also increased in the tumor as compared to the mucosa. However, clinicopathological analysis indicated that, in patients with tumors >5 cm, the expression of MICA and MICB in the tumor did not differ from that of the mucosa, and tumors >5 cm showed significantly higher MICA and MICB expression than tumors ≤5 cm. Patients presenting tumors >5 cm that expressed MICA and MICB had substantially shorter survival than those with large tumors that did not express these ligands. Our results suggest that locally sustained expression of MICA and MICB in the tumor may contribute to the malignant progression of GC and that expression of these ligands predicts an unfavorable prognosis in GC patients presenting large tumors. PMID:26708143

  4. Clinical significance of tumor expression of major histocompatibility complex class I-related chains A and B (MICA/B) in gastric cancer patients

    PubMed Central

    RIBEIRO, CAROLINA HAGER; KRAMM, KARINA; GÁLVEZ-JIRÓN, FELIPE; POLA, VÍCTOR; BUSTAMANTE, MARCO; CONTRERAS, HECTOR R.; SABAG, ANDREA; GARRIDO-TAPIA, MACARENA; HERNÁNDEZ, CAROLINA J.; ZÚÑIGA, ROBERTO; COLLAZO, NORBERTO; SOTELO, PABLO HERNÁN; MORALES, CAMILA; MERCADO, LUIS; CATALÁN, DIEGO; AGUILLÓN, JUAN CARLOS; MOLINA, MARÍA CARMEN

    2016-01-01

    Gastric cancer (GC) is the third most common cause of cancer death worldwide. Natural killer cells play an important role in the immune defense against transformed cells. They express the activating receptor NKG2D, whose ligands belong to the MIC and ULBP/RAET family. Although it is well established that these ligands are generally expressed in tumors, the association between their expression in the tumor and gastric mucosa and clinical parameters and prognosis of GC remains to be addressed. In the present study, MICA and MICB expression was analyzed, by flow cytometry, in 23 and 20 pairs of gastric tumor and adjacent non-neoplasic gastric mucosa, respectively. Additionally, ligands expression in 13 tumors and 7 gastric mucosa samples from GC patients were evaluated by immunohistochemistry. The mRNA levels of MICA in 9 pairs of tumor and mucosa were determined by quantitative PCR. Data were associated with the clinicopathological characteristics and the patient outcome. MICA expression was observed in 57% of tumors (13/23) and 44% of mucosal samples (10/23), while MICB was detected in 50% of tumors (10/20) and 45% of mucosal tissues (9/20). At the protein level, ligand expression was significantly higher in the tumor than in the gastric mucosa. MICA mRNA levels were also increased in the tumor as compared to the mucosa. However, clinicopathological analysis indicated that, in patients with tumors >5 cm, the expression of MICA and MICB in the tumor did not differ from that of the mucosa, and tumors >5 cm showed significantly higher MICA and MICB expression than tumors ≤5 cm. Patients presenting tumors >5 cm that expressed MICA and MICB had substantially shorter survival than those with large tumors that did not express these ligands. Our results suggest that locally sustained expression of MICA and MICB in the tumor may contribute to the malignant progression of GC and that expression of these ligands predicts an unfavorable prognosis in GC patients presenting large tumors. PMID:26708143

  5. Online Courses and Optimal Class Size: A Complex Formula

    ERIC Educational Resources Information Center

    Arzt, Judy

    2011-01-01

    The purpose of this study was to conduct descriptive, exploratory research to answer the questions: What is the ideal class size for online courses? What are the variables that affect optimal class size in this environment? As a study of the literature, the goal was to collect research-based evidence supporting optimal class size. The initial…

  6. Complexities and complications: intersections of class and sexuality.

    PubMed

    Taylor, Yvette

    2009-01-01

    I explore some questions and dilemmas raised by considering social class, gender, and sexuality within the same interconnecting research framework. I begin with attention to the theoretical development of intersectionality, arising from feminist conceptualizations of "differences that matter," and the ways these are included in or excluded from research agendas. Arguing that interconnections between class and sexuality have often been neglected in such moves, I seek to progress beyond intersectionality as a theoretical paradigm, toward understanding intersectionality as a lived experience. I draw on a case study of working-class lesbian lives to bridge the gap between theorization of intersectionality and the research application of this. PMID:19363764

  7. Characterization of Bison bison major histocompatibitity complex class I haplotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    American bison (Bison bison) are highly susceptible to malignant catarrhal fever (MCF). Nevertheless, 20% of clinically normal bison have antibodies to ovine berpesvirus-2 (OvHV-2), the etiologic agent of MCF in North America. The bison MHC class II (MHC-II) genes were characterized in a previous s...

  8. Characterisation of Major Histocompatibility Complex Class I in the Australian Cane Toad, Rhinella marina

    PubMed Central

    Lillie, Mette; Shine, Richard; Belov, Katherine

    2014-01-01

    The Major Histocompatibility Complex (MHC) class I is a highly variable gene family that encodes cell-surface receptors vital for recognition of intracellular pathogens and initiation of immune responses. The MHC class I has yet to be characterised in bufonid toads (Order: Anura; Suborder: Neobatrachia; Family: Bufonidae), a large and diverse family of anurans. Here we describe the characterisation of a classical MHC class I gene in the Australian cane toad, Rhinella marina. From 25 individuals sampled from the Australian population, we found only 3 alleles at this classical class I locus. We also found large number of class I alpha 1 alleles, implying an expansion of class I loci in this species. The low classical class I genetic diversity is likely the result of repeated bottleneck events, which arose as a result of the cane toad's complex history of introductions as a biocontrol agent and its subsequent invasion across Australia. PMID:25093458

  9. Disruption of the Class IIa HDAC Corepressor Complex Increases Energy Expenditure and Lipid Oxidation.

    PubMed

    Gaur, Vidhi; Connor, Timothy; Sanigorski, Andrew; Martin, Sheree D; Bruce, Clinton R; Henstridge, Darren C; Bond, Simon T; McEwen, Kevin A; Kerr-Bayles, Lyndal; Ashton, Trent D; Fleming, Cassandra; Wu, Min; Pike Winer, Lisa S; Chen, Denise; Hudson, Gregg M; Schwabe, John W R; Baar, Keith; Febbraio, Mark A; Gregorevic, Paul; Pfeffer, Frederick M; Walder, Ken R; Hargreaves, Mark; McGee, Sean L

    2016-09-13

    Drugs that recapitulate aspects of the exercise adaptive response have the potential to provide better treatment for diseases associated with physical inactivity. We previously observed reduced skeletal muscle class IIa HDAC (histone deacetylase) transcriptional repressive activity during exercise. Here, we find that exercise-like adaptations are induced by skeletal muscle expression of class IIa HDAC mutants that cannot form a corepressor complex. Adaptations include increased metabolic gene expression, mitochondrial capacity, and lipid oxidation. An existing HDAC inhibitor, Scriptaid, had similar phenotypic effects through disruption of the class IIa HDAC corepressor complex. Acute Scriptaid administration to mice increased the expression of metabolic genes, which required an intact class IIa HDAC corepressor complex. Chronic Scriptaid administration increased exercise capacity, whole-body energy expenditure and lipid oxidation, and reduced fasting blood lipids and glucose. Therefore, compounds that disrupt class IIa HDAC function could be used to enhance metabolic health in chronic diseases driven by physical inactivity. PMID:27626651

  10. The Zhamanshin impact feature: A new class of complex crater?

    NASA Technical Reports Server (NTRS)

    Garvin, J. B.; Schnetzler, C. C.

    1992-01-01

    The record of 10-km-scale impact events of Quaternary age includes only two 'proven' impact structures: the Zhamanshin Impact Feature (ZIF) and the Bosumtwi Impact Crater (BIC). What makes these impact landforms interesting from the standpoint of recent Earth history is their almost total lack of morphologic similarity, in spite of similar absolute ages and dimensions. The BIC resembles pristine complex craters on the Moon to first order (i.e., 'U'-shaped topographic cross section with preserved rim), while the ZIF displays virtually none of the typical morphologic elements of a 13- to 14-km-diameter complex crater. Indeed, this apparent lack of a craterlike surficial topographic expression initially led Soviet geologists to conclude that the structure was only 5.5 to 6 km in diameter and at least 4.5 Ma in age. However, more recent drilling and geophysical observations at the ZIF have indicated that its pre-erosional diameter is at least 13.5 km, and that its age is most probably 0.87 Ma. Why the present topographic expression of a 13.5-km complex impact crater less than 1 m.y. old most closely resembles heavily degraded Mesozoic shield craters such as Lappajarvi is a question of considerable debate. Hypotheses for the lack of a clearly defined craterlike form at the ZIF include a highly oblique impact, a low-strength 'cometary' projectile, weak or water-saturated target materials, and anomalous erosion patterns. The problem remains unresolved because typical erosion rates within the arid sedimentary platform environment of central Kazakhstan in which the ZIF is located are typically low; it would require at least a factor of 10 greater erosion at the ZIF in order to degrade the near-rim ejecta typical of a 13.5-km complex crater by hundreds of meters in only 0.87 Ma, and to partially infill an inner cavity with 27 cu km (an equivalent uniform thickness of infill of 166 m). Our analysis of the degree of erosion and infill at the ZIF calls for rates in the 0.19 to

  11. Expression Regulation of Major Histocompatibility Complex Class I and Class II Encoding Genes

    PubMed Central

    van den Elsen, Peter J.

    2011-01-01

    Major histocompatibility complex (MHC)-I and MHC-II molecules play an essential role in the immune response to pathogens by virtue of their ability to present peptides to CD8+ and CD4+ T cells, respectively. Given this critical role, MHC-I and MHC-II genes are regulated in a tight fashion at the transcriptional level by a variety of transcription factors that interact with conserved cis-acting regulatory promoter elements. In addition to the activities of these regulatory factors, modification of chromatin also plays an essential role in the efficient transcription of these genes to meet with local requirement for an effective immune response. The focus of this review is on the transcription factors that interact with conserved cis-acting promoter elements and the epigenetic mechanisms that modulate induced and constitutive expression of these MHC genes. PMID:22566838

  12. Inhibition of selective signaling events in natural killer cells recognizing major histocompatibility complex class I.

    PubMed Central

    Kaufman, D S; Schoon, R A; Robertson, M J; Leibson, P J

    1995-01-01

    Many studies have characterized the transmembrane signaling events initiated after T-cell antigen receptor recognition of major histocompatibility complex (MHC)-bound peptides. Yet, little is known about signal transduction from a set of MHC class I recognizing receptors on natural killer (NK) cells whose ligation dramatically inhibits NK cell-mediated killing. In this study we evaluated the influence of MHC recognition on the proximal signaling events in NK cells binding tumor targets. We utilized two experimental models where NK cell-mediated cytotoxicity was fully inhibited by the recognition of specific MHC class I molecules. NK cell binding to either class I-deficient or class I-transfected target cells initiated rapid protein tyrosine kinase activation. In contrast, whereas NK cell binding to class I-deficient targets led to inositol phosphate release and increased intracellular free calcium ([Ca2+]i), NK recognition of class I-bearing targets did not induce the activation of these phospholipase C-dependent signaling events. The recognition of class I by NK cells clearly had a negative regulatory effect since blocking this interaction using anti-class I F(ab')2 fragments increased inositol 1,4,5-trisphosphate release and [Ca2+]i and increased the lysis of the targets. These results suggest that one of the mechanisms by which NK cell recognition of specific MHC class I molecules can block the development of cell-mediated cytotoxicity is by inhibiting specific critical signaling events. Images Fig. 2 Fig. 4 PMID:7604018

  13. Regulation of calreticulin–major histocompatibility complex (MHC) class I interactions by ATP

    PubMed Central

    Wijeyesakere, Sanjeeva Joseph; Gagnon, Jessica K.; Arora, Karunesh; Brooks, Charles L.; Raghavan, Malini

    2015-01-01

    The MHC class I peptide loading complex (PLC) facilitates the assembly of MHC class I molecules with peptides, but factors that regulate the stability and dynamics of the assembly complex are largely uncharacterized. Based on initial findings that ATP, in addition to MHC class I-specific peptide, is able to induce MHC class I dissociation from the PLC, we investigated the interaction of ATP with the chaperone calreticulin, an endoplasmic reticulum (ER) luminal, calcium-binding component of the PLC that is known to bind ATP. We combined computational and experimental measurements to identify residues within the globular domain of calreticulin, in proximity to the high-affinity calcium-binding site, that are important for high-affinity ATP binding and for ATPase activity. High-affinity calcium binding by calreticulin is required for optimal nucleotide binding, but both ATP and ADP destabilize enthalpy-driven high-affinity calcium binding to calreticulin. ATP also selectively destabilizes the interaction of calreticulin with cellular substrates, including MHC class I molecules. Calreticulin mutants that affect ATP or high-affinity calcium binding display prolonged associations with monoglucosylated forms of cellular MHC class I, delaying MHC class I dissociation from the PLC and their transit through the secretory pathway. These studies reveal central roles for ATP and calcium binding as regulators of calreticulin–substrate interactions and as key determinants of PLC dynamics. PMID:26420867

  14. Cell stress-regulated human major histocompatibility complex class I gene expressed in gastrointestinal epithelium.

    PubMed Central

    Groh, V; Bahram, S; Bauer, S; Herman, A; Beauchamp, M; Spies, T

    1996-01-01

    Conventional major histocompatibility complex (MHC) class I genes encode molecules that present intracellular peptide antigens to T cells. They are ubiquitously expressed and regulated by interferon gamma. Two highly divergent human MHC class I genes, MICA and MICB, are regulated by promoter heat shock elements similar to those of HSP70 genes. MICA encodes a cell surface glycoprotein, which is not associated with beta 2-microglobulin, is conformationally stable independent of conventional class I peptide ligands, and almost exclusively expressed in gastrointestinal epithelium. Thus, this MHC class I molecule may function as an indicator of cell stress and may be recognized by a subset of gut mucosal T cells in an unusual interaction. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8901601

  15. Challenges in Integrating a Complex Systems Computer Simulation in Class: An Educational Design Research

    ERIC Educational Resources Information Center

    Loke, Swee-Kin; Al-Sallami, Hesham S.; Wright, Daniel F. B.; McDonald, Jenny; Jadhav, Sheetal; Duffull, Stephen B.

    2012-01-01

    Complex systems are typically difficult for students to understand and computer simulations offer a promising way forward. However, integrating such simulations into conventional classes presents numerous challenges. Framed within an educational design research, we studied the use of an in-house built simulation of the coagulation network in four…

  16. Porcine major histocompatibility complex (MHC) class I molecules and analysis of their peptide-binding specificities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In all vertebrate animals, CD8+ cytotoxic T lymphocytes (CTLs) are controlled by major histocompatibility complex class I (MHC-I) molecules, which are highly polymorphic peptide receptors selecting and presenting endogenously derived epitopes to circulating cytotoxic lymphocytes (CTLs). The polymorp...

  17. Cyclophilin C Participates in the US2-Mediated Degradation of Major Histocompatibility Complex Class I Molecules

    PubMed Central

    Chapman, Daniel C.; Stocki, Pawel; Williams, David B.

    2015-01-01

    Human cytomegalovirus uses a variety of mechanisms to evade immune recognition through major histocompatibility complex class I molecules. One mechanism mediated by the immunoevasin protein US2 causes rapid disposal of newly synthesized class I molecules by the endoplasmic reticulum-associated degradation pathway. Although several components of this degradation pathway have been identified, there are still questions concerning how US2 targets class I molecules for degradation. In this study we identify cyclophilin C, a peptidyl prolyl isomerase of the endoplasmic reticulum, as a component of US2-mediated immune evasion. Cyclophilin C could be co-isolated with US2 and with the class I molecule HLA-A2. Furthermore, it was required at a particular expression level since depletion or overexpression of cyclophilin C impaired the degradation of class I molecules. To better characterize the involvement of cyclophilin C in class I degradation, we used LC-MS/MS to detect US2-interacting proteins that were influenced by cyclophilin C expression levels. We identified malectin, PDIA6, and TMEM33 as proteins that increased in association with US2 upon cyclophilin C knockdown. In subsequent validation all were shown to play a functional role in US2 degradation of class I molecules. This was specific to US2 rather than general ER-associated degradation since depletion of these proteins did not impede the degradation of a misfolded substrate, the null Hong Kong variant of α1-antitrypsin. PMID:26691022

  18. Crystal structure of the N-myristoylated lipopeptide-bound MHC class I complex

    PubMed Central

    Morita, Daisuke; Yamamoto, Yukie; Mizutani, Tatsuaki; Ishikawa, Takeshi; Suzuki, Juri; Igarashi, Tatsuhiko; Mori, Naoki; Shiina, Takashi; Inoko, Hidetoshi; Fujita, Hiroaki; Iwai, Kazuhiro; Tanaka, Yoshimasa; Mikami, Bunzo; Sugita, Masahiko

    2016-01-01

    The covalent conjugation of a 14-carbon saturated fatty acid (myristic acid) to the amino-terminal glycine residue is critical for some viral proteins to function. This protein lipidation modification, termed N-myristoylation, is targeted by host cytotoxic T lymphocytes (CTLs) that specifically recognize N-myristoylated short peptides; however, the molecular mechanisms underlying lipopeptide antigen (Ag) presentation remain elusive. Here we show that a primate major histocompatibility complex (MHC) class I-encoded protein is capable of binding N-myristoylated 5-mer peptides and presenting them to specific CTLs. A high-resolution X-ray crystallographic analysis of the MHC class I:lipopeptide complex reveals an Ag-binding groove that is elaborately constructed to bind N-myristoylated short peptides rather than prototypic 9-mer peptides. The identification of lipopeptide-specific, MHC class I-restricted CTLs indicates that the widely accepted concept of MHC class I-mediated presentation of long peptides to CTLs may need some modifications to incorporate a novel MHC class I function of lipopeptide Ag presentation. PMID:26758274

  19. Crystal structure of the N-myristoylated lipopeptide-bound MHC class I complex.

    PubMed

    Morita, Daisuke; Yamamoto, Yukie; Mizutani, Tatsuaki; Ishikawa, Takeshi; Suzuki, Juri; Igarashi, Tatsuhiko; Mori, Naoki; Shiina, Takashi; Inoko, Hidetoshi; Fujita, Hiroaki; Iwai, Kazuhiro; Tanaka, Yoshimasa; Mikami, Bunzo; Sugita, Masahiko

    2016-01-01

    The covalent conjugation of a 14-carbon saturated fatty acid (myristic acid) to the amino-terminal glycine residue is critical for some viral proteins to function. This protein lipidation modification, termed N-myristoylation, is targeted by host cytotoxic T lymphocytes (CTLs) that specifically recognize N-myristoylated short peptides; however, the molecular mechanisms underlying lipopeptide antigen (Ag) presentation remain elusive. Here we show that a primate major histocompatibility complex (MHC) class I-encoded protein is capable of binding N-myristoylated 5-mer peptides and presenting them to specific CTLs. A high-resolution X-ray crystallographic analysis of the MHC class I:lipopeptide complex reveals an Ag-binding groove that is elaborately constructed to bind N-myristoylated short peptides rather than prototypic 9-mer peptides. The identification of lipopeptide-specific, MHC class I-restricted CTLs indicates that the widely accepted concept of MHC class I-mediated presentation of long peptides to CTLs may need some modifications to incorporate a novel MHC class I function of lipopeptide Ag presentation. PMID:26758274

  20. Induction of class II major histocompatibility complex expression in human multiple myeloma cells by retinoid.

    PubMed

    Sanda, Takaomi; Iida, Shinsuke; Kayukawa, Satoshi; Ueda, Ryuzo

    2007-01-01

    Class II major histocompatibility complex (MHC II) is normally silenced in plasma/multiple myeloma (MM) cells at the transcriptional level through downregulation of class II transactivator (CIITA), allowing MM cells to escape from immunological responses. Here we demonstrate that a retinoic acid receptor-alpha/beta-selective retinoid Am80 (tamibarotene) could induce the expression of functional MHC II molecules in human MM cell lines. Am80 upregulated expression of the interferon regulatory factor-1 gene, followed by enhancement of CIITA expression. This is the first report demonstrating that retinoid can induce the expression of MHC II in terminally-differentiated plasma/MM cells. PMID:17229644

  1. Complex structure of a bacterial class 2 histone deacetylase homologue with a trifluoromethylketone inhibitor

    SciTech Connect

    Nielsen, Tine Kragh; Hildmann, Christian; Riester, Daniel; Wegener, Dennis; Schwienhorst, Andreas; Ficner, Ralf

    2007-04-01

    The crystal structure of HDAH FB188 in complex with a trifluoromethylketone at 2.2 Å resolution is reported and compared to a previously determined inhibitor complex. Histone deacetylases (HDACs) have emerged as attractive targets in anticancer drug development. To date, a number of HDAC inhibitors have been developed and most of them are hydroxamic acid derivatives, typified by suberoylanilide hydroxamic acid (SAHA). Not surprisingly, structural information that can greatly enhance the design of novel HDAC inhibitors is so far only available for hydroxamic acids in complex with HDAC or HDAC-like enzymes. Here, the first structure of an enzyme complex with a nonhydroxamate HDAC inhibitor is presented. The structure of the trifluoromethyl ketone inhibitor 9,9,9-trifluoro-8-oxo-N-phenylnonanamide in complex with bacterial FB188 HDAH (histone deacetylase-like amidohydrolase from Bordetella/Alcaligenes strain FB188) has been determined. HDAH reveals high sequential and functional homology to human class 2 HDACs and a high structural homology to human class 1 HDACs. Comparison with the structure of HDAH in complex with SAHA reveals that the two inhibitors superimpose well. However, significant differences in binding to the active site of HDAH were observed. In the presented structure the O atom of the trifluoromethyl ketone moiety is within binding distance of the Zn atom of the enzyme and the F atoms participate in interactions with the enzyme, thereby involving more amino acids in enzyme–inhibitor binding.

  2. Identification of amino acid networks governing catalysis in the closed complex of class I terpene synthases.

    PubMed

    Schrepfer, Patrick; Buettner, Alexander; Goerner, Christian; Hertel, Michael; van Rijn, Jeaphianne; Wallrapp, Frank; Eisenreich, Wolfgang; Sieber, Volker; Kourist, Robert; Brück, Thomas

    2016-02-23

    Class I terpene synthases generate the structural core of bioactive terpenoids. Deciphering structure-function relationships in the reactive closed complex and targeted engineering is hampered by highly dynamic carbocation rearrangements during catalysis. Available crystal structures, however, represent the open, catalytically inactive form or harbor nonproductive substrate analogs. Here, we present a catalytically relevant, closed conformation of taxadiene synthase (TXS), the model class I terpene synthase, which simulates the initial catalytic time point. In silico modeling of subsequent catalytic steps allowed unprecedented insights into the dynamic reaction cascades and promiscuity mechanisms of class I terpene synthases. This generally applicable methodology enables the active-site localization of carbocations and demonstrates the presence of an active-site base motif and its dominating role during catalysis. It additionally allowed in silico-designed targeted protein engineering that unlocked the path to alternate monocyclic and bicyclic synthons representing the basis of a myriad of bioactive terpenoids. PMID:26842837

  3. Maslov complex germ method for systems with second-class constraints

    NASA Astrophysics Data System (ADS)

    Shvedov, O. Yu.

    2016-03-01

    We study the semiclassical mechanics of systems with second-class constraints. We assume that the quantum mechanics of such a system is constructed by the Batalin-Fradkin-Tyutin method, where some additional coordinates and momenta are introduced and second-class constraints are converted into firstclass constraints. We also assume that the algebraic quantization method is used to quantize the extended system. To construct the semiclassical approximation, we use the Maslov complex germ theory. We study the semiclassical states of a system with second-class constraints, their scalar product, and the action of semiclassical observables in the first order of the semiclassical expansion. We consider the transformation of semiclassical states in the course of evolution.

  4. Identification of amino acid networks governing catalysis in the closed complex of class I terpene synthases

    PubMed Central

    Buettner, Alexander; Goerner, Christian; Hertel, Michael; van Rijn, Jeaphianne; Wallrapp, Frank; Eisenreich, Wolfgang; Sieber, Volker; Kourist, Robert; Brück, Thomas

    2016-01-01

    Class I terpene synthases generate the structural core of bioactive terpenoids. Deciphering structure–function relationships in the reactive closed complex and targeted engineering is hampered by highly dynamic carbocation rearrangements during catalysis. Available crystal structures, however, represent the open, catalytically inactive form or harbor nonproductive substrate analogs. Here, we present a catalytically relevant, closed conformation of taxadiene synthase (TXS), the model class I terpene synthase, which simulates the initial catalytic time point. In silico modeling of subsequent catalytic steps allowed unprecedented insights into the dynamic reaction cascades and promiscuity mechanisms of class I terpene synthases. This generally applicable methodology enables the active-site localization of carbocations and demonstrates the presence of an active-site base motif and its dominating role during catalysis. It additionally allowed in silico-designed targeted protein engineering that unlocked the path to alternate monocyclic and bicyclic synthons representing the basis of a myriad of bioactive terpenoids. PMID:26842837

  5. Multi-class and multi-scale models of complex biological phenomena.

    PubMed

    Yu, Jessica S; Bagheri, Neda

    2016-06-01

    Computational modeling has significantly impacted our ability to analyze vast (and exponentially increasing) quantities of experimental data for a variety of applications, such as drug discovery and disease forecasting. Single-scale, single-class models persist as the most common group of models, but biological complexity often demands more sophisticated approaches. This review surveys modeling approaches that are multi-class (incorporating multiple model types) and/or multi-scale (accounting for multiple spatial or temporal scales) and describes how these models, and combinations thereof, should be used within the context of the problem statement. We end by highlighting agent-based models as an intuitive, modular, and flexible framework within which multi-scale and multi-class models can be implemented. PMID:27115496

  6. Interactions between the Class II Transactivator and CREB Binding Protein Increase Transcription of Major Histocompatibility Complex Class II Genes

    PubMed Central

    Fontes, Joseph D.; Kanazawa, Satoshi; Jean, Dickson; Peterlin, B. Matija

    1999-01-01

    Class II major histocompatibility (class II) genes are regulated in a B-cell-specific and gamma interferon-inducible fashion. The master switch for the expression of these genes is the class II transactivator (CIITA). In this report, we demonstrate that one of the functions of CIITA is to recruit the CREB binding protein (CBP) to class II promoters. Not only functional but also specific binding interactions between CIITA and CBP were demonstrated. Moreover, a dominant negative form of CBP decreased the activity of class II promoters and levels of class II determinants on the surface of cells. Finally, the inhibition of class II gene expression by the glucocorticoid hormone could be attributed to the squelching of CBP by the glucocorticoid receptor. We conclude that CBP, a histone acetyltransferase, plays an important role in the transcription of class II genes. PMID:9858618

  7. Cytokines Regulate Proteolysis in Major Histocompatibility Complex Class II–Dependent Antigen Presentation by Dendritic Cells

    PubMed Central

    Fiebiger, Edda; Meraner, Paul; Weber, Ekkehard; Fang, I-Fei; Stingl, Georg; Ploegh, Hidde; Maurer, Dieter

    2001-01-01

    Endo/lysosomal proteases control two key events in antigen (Ag) presentation: the degradation of protein Ag and the generation of peptide-receptive major histocompatibility complex (MHC) class II molecules. Here we show that the proinflammatory cytokines tumor necrosis factor α and interleukin (IL)-1β rapidly increase the activity of cathepsin (cat) S and catB in human dendritic cells (DCs). As a consequence, a wave of MHC class II sodium dodecyl sulfate stable dimer formation ensues in a catS-dependent fashion. In contrast, the antiinflammatory cytokine IL-10 renders DCs incapable of upregulating catS and catB activity and in fact, attenuates the level of both enzymes. Suppressed catS and catB activity delays MHC class II sodium dodecyl sulfate stable dimer formation and impairs Ag degradation. In DCs exposed to tetanus toxoid, IL-10 accordingly reduces the number of MHC class II–peptide complexes accessible to tetanus toxoid–specific T cell receptors, as analyzed by measuring T cell receptor downregulation in Ag-specific T cell clones. Thus, the control of protease activity by pro- and antiinflammatory cytokines is an essential feature of the Ag presentation properties of DCs. PMID:11304549

  8. Complex architecture of major histocompatibility complex class II promoters: reiterated motifs and conserved protein-protein interactions.

    PubMed Central

    Jabrane-Ferrat, N; Fontes, J D; Boss, J M; Peterlin, B M

    1996-01-01

    The S box (also known as at the H, W, or Z box) is the 5'-most element of the conserved upstream sequences in promoters of major histocompatibility complex class II genes. It is important for their B-cell-specific and interferon gamma-inducible expression. In this study, we demonstrate that the S box represents a duplication of the downstream X box. First, RFX, which is composed of the RFX5-p36 heterodimer that binds to the X box, also binds to the S box and its 5'-flanking sequence. Second, NF-Y, which binds to the Y box and increases interactions between RFX and the X box, also increases the binding of RFX to the S box. Third, RFXs bound to S and X boxes interact with each other in a spatially constrained manner. Finally, we confirmed these protein-protein and protein-DNA interactions by expressing a hybrid RFX5-VP16 protein in cells. We conclude that RFX binds to S and X boxes and that complex interactions between RFX and NF-Y direct B-cell-specific and interferon gamma-inducible expression or major histocompatibility complex class II genes. PMID:8756625

  9. Major histocompatibility complex class II deficiency complicated by Mycobacterium avium complex in a boy of mixed ethnicity.

    PubMed

    Dimitrova, Dimana; Ong, Peck Y; O'Gorman, Maurice R G; Church, Joseph A

    2014-08-01

    Major histocompatibility complex class II (MHCII) deficiency represents a rare form of severe immunodeficiency associated with increased susceptibility to viral, bacterial, and fungal pathogens and commonly leads to failure to thrive and early death. This autosomal recessive disorder is caused by mutations in MHCII transcription regulator genes, resulting in impaired expression of MHCII, and it is usually seen in consanguineous populations. Our patient presented at age 15 months with a history of developmental delay, multiple respiratory infections and skin abscesses, and recently, at 5 years of age, he was found to have disseminated Mycobacterium avium complex. His mother is Mexican-American, and his father is Persian. Laboratory investigations showed hypogammaglobulinemia, modest T-lymphopenia, borderline mitogen responses, absent tetanus toxoid and candida antigen lymphoproliferative assays, and absent tetanus toxoid and Haemophilus influenzae type b antibody levels. Flow cytometry demonstrated absent HLA-DR antigen on monocytes and B-cells, and a diagnosis of MHCII deficiency was made. Genetic analysis yielded a homozygous pathogenic class II transactivator (CIITA) mutation. The same mutation was found in both parents. Coincidently, an Xq28 microduplication was identified and likely was the cause of the patient's developmental delay. This patient demonstrated some of the typical features of MHCII deficiency with the addition of several unique findings: disseminated M. avium complex, homozygosity in a CIITA mutation despite remarkably diverse parental ethnicity, and coincident Xq28 microdeletion with mild intellectual disability. PMID:24789686

  10. Characterization of Two Classes of Small Molecule Inhibitors of Arp2/3 Complex

    SciTech Connect

    Nolen, B.; Tomasevic, N; Russell, A; Pierce, D; Jia, Z; McCormick, C; Hartman, J; Sakowicz, R; Pollard, T

    2009-01-01

    Polymerization of actin filaments directed by the actin-related protein (Arp)2/3 complex supports many types of cellular movements. However, questions remain regarding the relative contributions of Arp2/3 complex versus other mechanisms of actin filament nucleation to processes such as path finding by neuronal growth cones; this is because of the lack of simple methods to inhibit Arp2/3 complex reversibly in living cells. Here we describe two classes of small molecules that bind to different sites on the Arp2/3 complex and inhibit its ability to nucleate actin filaments. CK-0944636 binds between Arp2 and Arp3, where it appears to block movement of Arp2 and Arp3 into their active conformation. CK-0993548 inserts into the hydrophobic core of Arp3 and alters its conformation. Both classes of compounds inhibit formation of actin filament comet tails by Listeria and podosomes by monocytes. Two inhibitors with different mechanisms of action provide a powerful approach for studying the Arp2/3 complex in living cells.

  11. Multifunctional class I transcription in Trypanosoma brucei depends on a novel protein complex

    PubMed Central

    Brandenburg, Jens; Schimanski, Bernd; Nogoceke, Everson; Nguyen, Tu N; Padovan, Júlio C; Chait, Brian T; Cross, George A M; Günzl, Arthur

    2007-01-01

    The vector-borne, protistan parasite Trypanosoma brucei is the only known eukaryote with a multifunctional RNA polymerase I that, in addition to ribosomal genes, transcribes genes encoding the parasite's major cell-surface proteins—the variant surface glycoprotein (VSG) and procyclin. In the mammalian bloodstream, antigenic variation of the VSG coat is the parasite's means to evade the immune response, while procyclin is necessary for effective establishment of trypanosome infection in the fly. Moreover, the exceptionally high efficiency of mono-allelic VSG expression is essential to bloodstream trypanosomes since its silencing caused rapid cell-cycle arrest in vitro and clearance of parasites from infected mice. Here we describe a novel protein complex that recognizes class I promoters and is indispensable for class I transcription; it consists of a dynein light chain and six polypeptides that are conserved only among trypanosomatid parasites. In accordance with an essential transcriptional function of the complex, silencing the expression of a key subunit was lethal to bloodstream trypanosomes and specifically affected the abundance of rRNA and VSG mRNA. The complex was dubbed class I transcription factor A. PMID:17972917

  12. The Atiyah class and complex structure stabilization in heterotic Calabi-Yau compactifications

    NASA Astrophysics Data System (ADS)

    Anderson, Lara B.; Gray, James; Lukas, Andre; Ovrut, Burt

    2011-10-01

    Holomorphic gauge fields in N = 1 supersymmetri cheterotic compactifications can constrain the complex structure moduli of a Calabi-Yau manifold. In this paper, the tools necessary to use holomorphic bundles as a mechanism for moduli stabilization are systematically developed. We review the requisite deformation theory — including the Atiyah class, which determines the deformations of the complex structure for which the gauge bundle becomes non-holomorphic and, hence, non-supersymmetric. In addition, two equivalent approaches to this mechanism of moduli stabilization are presented. The first isan efficient computational algorithm for determining the supersymmetric moduli space, while the second is an F-term potential in the four-dimensional theory associated with vector bundle holomorphy. These three methods are proven to be rigorously equivalent. We present explicit examples in which large numbers of complex structure moduli are stabilized. Finally, higher-order corrections to the moduli space are discussed.

  13. Carbonic Anhydrase Inhibitors. Part 541: Metal Complexes of Heterocyclic Sulfonamides: A New Class of Antiglaucoma Agents

    PubMed Central

    Scozzafava, Andrea; Jitianu, Andrei

    1997-01-01

    Metal complexes of heterocyclic sulfonamides possessing carbonic anhydrase (CA) inhibitory properties were recently shown to be useful as intraocular pressure (IOP) lowering agents in experimental animals, and might be developed as a novel class of antiglaucoma drugs. Here we report the synthesis of a heterocyclic sulfonamide CA inhibitor and of the metal complexes containing main group metal ions, such as Be(II), Mg(II), Al(III), Zn(II), Cd(II) and Hg(II) and the new sulfonamide as well as 5-amino-1,3,4-thiadiazole-2-sulfonamide as ligands. The new complexes were characterized by standard physico-chemical procedures, and assayed as inhibitors of three CA isozymes, CA I, II and IV. Some of them (but not the parent sulfonamides) strongly lowered IOP in rabbits when administered as a 2% solution into the eye. PMID:18475811

  14. Predicting protein structural classes based on complex networks and recurrence analysis.

    PubMed

    Olyaee, Mohammad H; Yaghoubi, Ali; Yaghoobi, Mahdi

    2016-09-01

    Protein sequences are divided into four structural classes. The determination of class is a challenging and beneficial task in the bioinformatics field. Several methods have been proposed to this end, but most utilize too many features and produce unsuitable results. In the present, features are extracted based on the predicted secondary structures. At first, predicted secondary structure sequences are mapped into two time series by the chaos game representation. Then, a recurrence matrix is calculated from each of the time series. The recurrence matrix is identified with the adjacency matrix of a complex network and measures are applied for the characterization of complex networks to these recurrence matrixes. For a given protein sequence, a total of 24 characteristic features can be calculated and these are fed into Fisher's discriminated analysis algorithm for classification. To examine the proposed method, two widely used low similarity benchmark datasets design and test its performance. A comparison with the results of existing methods shows that the current study's approach provides a satisfactory performance for protein structural class prediction. PMID:27320678

  15. Rhinovirus infection induces major histocompatibility complex class I and costimulatory molecule upregulation on respiratory epithelial cells.

    PubMed

    Papi, A; Stanciu, L A; Papadopoulos, N G; Teran, L M; Holgate, S T; Johnston, S L

    2000-05-01

    Human respiratory epithelial cells may act as antigen-presenting cells during respiratory viral infections. In addition to major histocompatibility complex (MHC) molecules, antigen presentation requires participation of costimulatory molecules. Here the authors investigated class I and class II antigens and B7-1 and B7-2 costimulatory molecule expression in human A549 pulmonary epithelial cells and primary bronchial epithelial cells (HBECs) at baseline and after rhinovirus infection. Constitutive expression of MHC class I and B7-1 molecules was observed on both cell types. MHC class I molecules were up-regulated by rhinovirus infection, while B7-1 was up-regulated only on A549 cells. B7-2 molecules were constitutively expressed at a low level and were up-regulated by rhinovirus only on HBECs. Rhinovirus induction of antigen-presenting molecule expression on A549 cells was accompanied by cellular activation in terms of induction of release of the chemokines RANTES and Groalpha. These data show that respiratory epithelium expresses full antigen-presentation machinery and that rhinovirus infection up-regulates this expression. PMID:10823784

  16. Binding and activation of major histocompatibility complex class II-deficient macrophages by staphylococcal exotoxins

    NASA Technical Reports Server (NTRS)

    Beharka, A. A.; Armstrong, J. W.; Iandolo, J. J.; Chapes, S. K.; Spooner, B. S. (Principal Investigator)

    1994-01-01

    Macrophages from C2D transgenic mice deficient in the expression of major histocompatibility complex (MHC) class II proteins were used to identify binding sites for superantigens distinct from the MHC class II molecule. Iodinated staphylococcal enterotoxins A and B (SEA and SEB) and exfoliative toxins A and B (ETA and ETB) bound to C2D macrophages in a concentration-dependent and competitive manner. All four toxins increased F-actin concentration within 30 s of their addition to C2D macrophages, indicating that signal transduction occurred in response to toxin in the absence of class II MHC. Furthermore, ETA, ETB, SEA, and, to a lesser extent, SEB induced C2D macrophages to produce interleukin 6. Several molecular species on C2D macrophages with molecular masses of 140, 97, 61, 52, 43, and 37 kDa bound SEA in immunoprecipitation experiments. These data indicate the presence of novel, functionally active toxin binding sites on murine macrophages distinct from MHC class II molecules.

  17. Enhanced Direct Major Histocompatibility Complex Class I Self-Antigen Presentation Induced by Chlamydia Infection

    PubMed Central

    Cram, Erik D.; Simmons, Ryan S.; Palmer, Amy L.; Hildebrand, William H.; Rockey, Daniel D.

    2015-01-01

    The direct major histocompatibility complex (MHC) class I antigen presentation pathway ensures intracellular peptides are displayed at the cellular surface for recognition of infected or transformed cells by CD8+ cytotoxic T lymphocytes. Chlamydia spp. are obligate intracellular bacteria and, as such, should be targeted by CD8+ T cells. It is likely that Chlamydia spp. have evolved mechanisms to avoid the CD8+ killer T cell responses by interfering with MHC class I antigen presentation. Using a model system of self-peptide presentation which allows for posttranslational control of the model protein's stability, we tested the ability of various Chlamydia species to alter direct MHC class I antigen presentation. Infection of the JY lymphoblastoid cell line limited the accumulation of a model host protein and increased presentation of the model-protein-derived peptides. Enhanced self-peptide presentation was detected only when presentation was restricted to defective ribosomal products, or DRiPs, and total MHC class I levels remained unaltered. Skewed antigen presentation was dependent on a bacterial synthesized component, as evidenced by reversal of the observed phenotype upon preventing bacterial transcription, translation, and the inhibition of bacterial lipooligosaccharide synthesis. These data suggest that Chlamydia spp. have evolved to alter the host antigen presentation machinery to favor presentation of defective and rapidly degraded forms of self-antigen, possibly as a mechanism to diminish the presentation of peptides derived from bacterial proteins. PMID:26597986

  18. Mechanistic basis for unexpected bioavailability enhancement of polyelectrolyte complexes incorporating BCS class III drugs and carrageenans.

    PubMed

    Heinen, C; Reuss, S; Saaler-Reinhardt, S; Langguth, P

    2013-09-01

    The objective of this study was to investigate the potential of λ-carrageenan to work as an absorption modifying excipient in combination with formulations of BCS class 3 substances. Trospium chloride was used as a model BCS class 3 substance. Polyelectrolyte complexes of trospium and λ-carrageenan were produced by layer-by-layer complexation. A λ-carrageenan-containing formulation was administered either in capsules size 9 to rats by gavage or directly into ligated intestinal loops of rats. Exceptionally strong variations were observed in the plasma concentrations of the rats that received λ-carrageenan compared to the control group, but enhanced plasma concentrations were observed only in some of the rats. In vitro permeability studies were performed across Caco2-monolayers and across excised segments of rat jejunum in a modified Ussing chamber to learn more about the mechanism of absorption enhancement. The complex did not show any effect in Caco2-cells, but led to a major enhancement of permeability across excised segments in modified Ussing chambers. Carrageenan did not lead to alterations of tight junctions. The bioavailability enhancing effect thus was most likely due to an interaction of the polyelectrolyte-drug complex with the mucus, which provided an intimate contact between the drug and the absorbing surface. A similar effect was also achievable with other types of carrageenan and was also transferable to other compounds. In conclusion, λ-carrageenan-drug complexes show interesting excipient-drug-epithelium interactions - however, for full utilization of the permeation enhancing potential, an intimate and reproducible contact between absorbing epithelia and the complex is needed. PMID:23958316

  19. Covalent assembly of a soluble T cell receptor-peptide-major histocompatibility class I complex.

    PubMed Central

    Grégoire, C; Lin, S Y; Mazza, G; Rebai, N; Luescher, I F; Malissen, B

    1996-01-01

    We used stepwise photochemical cross-linking for specifically assembling soluble and covalent complexes made of a T-cell antigen receptor (TCR) and a class I molecule of the major histocompatibility complex (MHC) bound to an antigenic peptide. For that purpose, we have produced in myeloma cells a single-chain Fv construct of a TCR specific for a photoreactive H-2Kd-peptide complex. Photochemical cross-linking of this TCR single-chain Fv with a soluble form of the photoreactive H-2Kd-peptide ligand resulted in the formation of a ternary covalent complex. We have characterized the soluble ternary complex and showed that it reacted with antibodies specific for epitopes located either on the native TCR or on the Kd molecules. By preventing the fast dissociation kinetics observed with most T cell receptors, this approach provides a means of preparing soluble TCR-peptide-MHC complexes on large-scale levels. Images Fig. 3 Fig. 4 PMID:8692966

  20. Isolation and characterization of major histocompatibility complex class II B genes in cranes.

    PubMed

    Kohyama, Tetsuo I; Akiyama, Takuya; Nishida, Chizuko; Takami, Kazutoshi; Onuma, Manabu; Momose, Kunikazu; Masuda, Ryuichi

    2015-11-01

    In this study, we isolated and characterized the major histocompatibility complex (MHC) class II B genes in cranes. Genomic sequences spanning exons 1 to 4 were amplified and determined in 13 crane species and three other species closely related to cranes. In all, 55 unique sequences were identified, and at least two polymorphic MHC class II B loci were found in most species. An analysis of sequence polymorphisms showed the signature of positive selection and recombination. A phylogenetic reconstruction based on exon 2 sequences indicated that trans-species polymorphism has persisted for at least 10 million years, whereas phylogenetic analyses of the sequences flanking exon 2 revealed a pattern of concerted evolution. These results suggest that both balancing selection and recombination play important roles in the crane MHC evolution. PMID:26452363

  1. A recombinant, soluble, single-chain class I major histocompatibility complex molecule with biological activity.

    PubMed Central

    Mage, M G; Lee, L; Ribaudo, R K; Corr, M; Kozlowski, S; McHugh, L; Margulies, D H

    1992-01-01

    Heterodimeric class I major histocompatibility complex molecules, which consist of a 45-kDa heavy-chain and a 12-kDa beta 2-microglobulin (beta 2m) light chain, bind endogenously synthesized peptides for presentation to antigen-specific T cells. We have synthesized a gene encoding a single-chain, soluble class I molecule derived from mouse H-2Dd, in which the carboxyl terminus of beta 2m is linked via a peptide spacer to the amino terminus of the heavy chain. The chimeric protein is secreted efficiently from transfected L cells, is thermostable, and when loaded with an appropriate antigenic peptide, stimulates an H-2Dd-restricted antigen-specific T-cell hybridoma. Thus, functional binding of peptide does not require the complete dissociation of beta 2m, implying that a heavy chain/peptide complex is not an obligate intermediate in the assembly of the heavy-chain/beta 2m/peptide heterotrimer. Single-chain major histocompatibility complex molecules uniformly loaded with peptide have potential uses for structural studies, toxin or fluor conjugates, and vaccines. Images PMID:1438262

  2. Structures of the Class D Carbapenemase OXA-24 from Acinetobacter baumannii in Complex with Doripenem

    SciTech Connect

    Schneider, Kyle D.; Ortega, Caleb J.; Renck, Nicholas A.; Bonomo, Robert A.; Powers, Rachel A.; Leonard, David A.

    2012-02-08

    The emergence of class D {beta}-lactamases with carbapenemase activity presents an enormous challenge to health practitioners, particularly with regard to the treatment of infections caused by Gram-negative pathogens such as Acinetobacter baumannii. Unfortunately, class D {beta}-lactamases with carbapenemase activity are resistant to {beta}-lactamase inhibitors. To better understand the details of the how these enzymes bind and hydrolyze carbapenems, we have determined the structures of two deacylation-deficient variants (K84D and V130D) of the class D carbapenemase OXA-24 with doripenem bound as a covalent acyl-enzyme intermediate. Doripenem adopts essentially the same configuration in both OXA-24 variant structures, but varies significantly when compared to the non-carbapenemase class D member OXA-1/doripenem complex. The alcohol of the 6a hydroxyethyl moiety is directed away from the general base carboxy-K84, with implications for activation of the deacylating water. The tunnel formed by the Y112/M223 bridge in the apo form of OXA-24 is largely unchanged by the binding of doripenem. The presence of this bridge, however, causes the distal pyrrolidine/sulfonamide group to bind in a drastically different conformation compared to doripenem bound to OXA-1. The resulting difference in the position of the side-chain bridge sulfur of doripenem is consistent with the hypothesis that the tautomeric state of the pyrroline ring contributes to the different carbapenem hydrolysis rates of OXA-1 and OXA-24. These findings represent a snapshot of a key step in the catalytic mechanism of an important class D enzyme, and might be useful for the design of novel inhibitors.

  3. Complex networks for data-driven medicine: the case of Class III dentoskeletal disharmony

    NASA Astrophysics Data System (ADS)

    Scala, A.; Auconi, P.; Scazzocchio, M.; Caldarelli, G.; McNamara, JA; Franchi, L.

    2014-11-01

    In the last decade, the availability of innovative algorithms derived from complexity theory has inspired the development of highly detailed models in various fields, including physics, biology, ecology, economy, and medicine. Due to the availability of novel and ever more sophisticated diagnostic procedures, all biomedical disciplines face the problem of using the increasing amount of information concerning each patient to improve diagnosis and prevention. In particular, in the discipline of orthodontics the current diagnostic approach based on clinical and radiographic data is problematic due to the complexity of craniofacial features and to the numerous interacting co-dependent skeletal and dentoalveolar components. In this study, we demonstrate the capability of computational methods such as network analysis and module detection to extract organizing principles in 70 patients with excessive mandibular skeletal protrusion with underbite, a condition known in orthodontics as Class III malocclusion. Our results could possibly constitute a template framework for organising the increasing amount of medical data available for patients’ diagnosis.

  4. Structural Properties and Complexity of a New Network Class: Collatz Step Graphs

    PubMed Central

    Emmert-Streib, Frank

    2013-01-01

    In this paper, we introduce a biologically inspired model to generate complex networks. In contrast to many other construction procedures for growing networks introduced so far, our method generates networks from one-dimensional symbol sequences that are related to the so called Collatz problem from number theory. The major purpose of the present paper is, first, to derive a symbol sequence from the Collatz problem, we call the step sequence, and investigate its structural properties. Second, we introduce a construction procedure for growing networks that is based on these step sequences. Third, we investigate the structural properties of this new network class including their finite scaling and asymptotic behavior of their complexity, average shortest path lengths and clustering coefficients. Interestingly, in contrast to many other network models including the small-world network from Watts & Strogatz, we find that CS graphs become ‘smaller’ with an increasing size. PMID:23431377

  5. Efficient major histocompatibility complex class I presentation of exogenous antigen upon phagocytosis by macrophages.

    PubMed Central

    Kovacsovics-Bankowski, M; Clark, K; Benacerraf, B; Rock, K L

    1993-01-01

    Antigens in extracellular fluids can be processed and presented with major histocompatibility complex (MHC) class I molecules by a subset of antigen presenting cells (APCs). Chicken egg ovalbumin (Ova) linked to beads was presented with MHC class I molecules by these cells up to 10(4)-fold more efficiently than soluble Ova. This enhanced presentation was observed with covalently or noncovalently linked Ova and with beads of different compositions. A key parameter in the activity of these conjugates was the size of the beads. The APC that is responsible for this form of presentation is a macrophage. These cells internalize the antigen constructs through phagocytosis, since cytochalasin B inhibited presentation. Processing of the antigen and association with MHC class I molecules appears to occur intracellularly as presentation was observed under conditions where there was no detectable release of peptides into the extracellular fluids. When injected in vivo in C57BL/6 mice, Ova-beads, but not soluble Ova, primed CD4- CD8+ cytotoxic T lymphocytes (CTLs). Similar results were obtained in BALB/c mice immunized with beta-galactosidase-beads. The implications of these findings for development of nonliving vaccines that stimulate CTL immunity are discussed. PMID:8506338

  6. Isolation and characterization of major histocompatibility complex class IIB genes from the nurse shark.

    PubMed Central

    Bartl, S; Weissman, I L

    1994-01-01

    The major histocompatibility complex (MHC) contains a set of linked genes which encode cell surface proteins involved in the binding of small peptide antigens for their subsequent recognition by T lymphocytes. MHC proteins share structural features and the presence and location of polymorphic residues which play a role in the binding of antigens. In order to compare the structure of these molecules and gain insights into their evolution, we have isolated two MHC class IIB genes from the nurse shark, Ginglymostoma cirratum. Two clones, most probably alleles, encode proteins which differ by 13 amino acids located in the putative antigen-binding cleft. The protein structure and the location of polymorphic residues are similar to their mammalian counterparts. Although these genes appear to encode a typical MHC protein, no T-cell-mediated responses have been demonstrated in cartilaginous fish. The nurse shark represents the most phylogenetically primitive organism in which both class IIA [Kasahara, M., Vazquez, M., Sato, K., McKinney, E.C. & Flajnik, M.F. (1992) Proc. Natl. Acad. Sci USA 89, 6688-6692] and class IIB genes, presumably encoding the alpha/beta heterodimer, have been isolated. Images Fig. 2 PMID:8278377

  7. Engineering an intracellular pathway for major histocompatibility complex class II presentation of antigens.

    PubMed Central

    Wu, T C; Guarnieri, F G; Staveley-O'Carroll, K F; Viscidi, R P; Levitsky, H I; Hedrick, L; Cho, K R; August, J T; Pardoll, D M

    1995-01-01

    The presentation of antigenic peptides by major histocompatibility complex (MHC) class II molecules to CD4+ T cells is critical to the function of the immune system. In this study, we have utilized the sorting signal of the lysosomal-associated membrane protein LAMP-1 to target a model antigen, human papillomavirus 16 E7 (HPV-16 E7), into the endosomal and lysosomal compartments. The LAMP-1 sorting signal reroutes the antigen into the MHC class II processing pathway, resulting in enhanced presentation to CD4+ cells in vitro. In vivo immunization experiments in mice demonstrated that vaccinia containing the chimeric E7/LAMP-1 gene generated greater E7-specific lymphoproliferative activity, antibody titers, and cytotoxic T-lymphocyte activities than vaccinia containing the wild-type HPV-16 E7 gene. These results suggest that specific targeting of an antigen to the endosomal and lysosomal compartments enhances MHC class II presentation and vaccine potency. Images Fig. 2 Fig. 3 PMID:8524826

  8. The Integrator complex controls the termination of transcription at diverse classes of gene targets

    PubMed Central

    Skaar, Jeffrey R; Ferris, Andrea L; Wu, Xiaolin; Saraf, Anita; Khanna, Kum Kum; Florens, Laurence; Washburn, Michael P; Hughes, Stephen H; Pagano, Michele

    2015-01-01

    Complexes containing INTS3 and either NABP1 or NABP2 were initially characterized in DNA damage responses, but their biochemical function remained unknown. Using affinity purifications and HIV Integration targeting-sequencing (HIT-Seq), we find that these complexes are part of the Integrator complex, which binds RNA Polymerase II and regulates specific target genes. Integrator cleaves snRNAs as part of their processing to their mature form in a mechanism that is intimately coupled with transcription termination. However, HIT-Seq reveals that Integrator also binds to the 3′ end of replication-dependent histones and promoter proximal regions of genes with polyadenylated transcripts. Depletion of Integrator subunits results in transcription termination failure, disruption of histone mRNA processing, and polyadenylation of snRNAs and histone mRNAs. Furthermore, promoter proximal binding of Integrator negatively regulates expression of genes whose transcripts are normally polyadenylated. Integrator recruitment to all three gene classes is DSIF-dependent, suggesting that Integrator functions as a termination complex at DSIF-dependent RNA Polymerase II pause sites. PMID:25675981

  9. Class-first analysis in a continuum: an approach to the complexities of schools, society, and insurgent science

    NASA Astrophysics Data System (ADS)

    Valdiviezo, Laura Alicia

    2010-06-01

    This essay addresses Katherine Richardson Bruna's paper: Mexican Immigrant Transnational Social Capital and Class Transformation: Examining the Role of Peer Mediation in Insurgent Science, through five main points . First, I offer a comparison between the traditional analysis of classism in Latin America and Richardson Bruna's call for a class-first analysis in the North American social sciences where there has been a tendency to obviate the specific examination of class relations and class issues. Secondly, I discuss that a class-first analysis solely cannot suffice to depict the complex dimensions in the relations of schools and society. Thus, I suggest a continuum in the class-first analysis. Third, I argue that social constructions surrounding issues of language, ethnicity, and gender necessarily intersect with issues of class and that, in fact, those other constructions offer compatible epistemologies that aid in representing the complexity of social and institutional practices in the capitalist society. Richardson Bruna's analysis of Augusto's interactions with his teacher and peers in the science class provides a fourth point of discussion in this essay. As a final point in my response I discuss Richardson Bruna's idea of making accessible class-first analysis knowledge to educators and especially to science teachers.

  10. Diacylglycerol Kinase α Regulates Tubular Recycling Endosome Biogenesis and Major Histocompatibility Complex Class I Recycling*

    PubMed Central

    Xie, Shuwei; Naslavsky, Naava; Caplan, Steve

    2014-01-01

    Major histocompatibility complex class I (MHC I) presents intracellular-derived peptides to cytotoxic T lymphocytes and its subcellular itinerary is important in regulating the immune response. While a number of diacylglycerol kinase isoforms have been implicated in clathrin-dependent internalization, MHC I lacks the typical motifs known to mediate clathrin-dependent endocytosis. Here we show that depletion of diacylglycerol kinase α (DGKα), a kinase devoid of a clathrin-dependent adaptor protein complex 2 binding site, caused a delay in MHC I recycling to the plasma membrane without affecting the rate of MHC I internalization. We demonstrate that DGKα knock-down causes accumulation of intracellular and surface MHC I, resulting from decreased degradation. Furthermore, we provide evidence that DGKα is required for the generation of phosphatidic acid required for tubular recycling endosome (TRE) biogenesis. Moreover, we show that DGKα forms a complex with the TRE hub protein, MICAL-L1. Given that MICAL-L1 and the F-BAR-containing membrane-tubulating protein Syndapin2 associate selectively with phosphatidic acid, we propose a positive feedback loop in which DGKα generates phosphatidic acid to drive its own recruitment to TRE via its interaction with MICAL-L1. Our data support a novel role for the involvement of DGKα in TRE biogenesis and MHC I recycling. PMID:25248744

  11. Plasticity of empty major histocompatibility complex class I molecules determines peptide-selector function.

    PubMed

    van Hateren, Andy; Bailey, Alistair; Werner, Jörn M; Elliott, Tim

    2015-12-01

    Major histocompatibility complex class I (MHC I) proteins provide protection from intracellular pathogens and cancer via each of a cell's MHC I molecules binding and presenting a peptide to cytotoxic T lymphocytes. MHC I genes are highly polymorphic and can have significant diversity, with polymorphisms predominantly localised in the peptide-binding groove where they can change peptide-binding specificity. However, polymorphic residues may also determine other functional properties, such as how dependent MHC I alleles are on the peptide-loading complex for optimal acquisition of peptide cargo. We describe how differences in the peptide-binding properties of two MHC I alleles correlates with altered conformational flexibility in the peptide-empty state. We hypothesise that plasticity is an intrinsic property encoded by the protein sequence, and that co-ordinated movements of the membrane-proximal and membrane-distal domains collectively determines how dependent MHC I are on the peptide-loading complex for efficient assembly with high affinity peptides. PMID:25818313

  12. Naturally Occurring Class A ß-Lactamases from the Burkholderia cepacia Complex

    PubMed Central

    Poirel, Laurent; Rodriguez-Martinez, José-Manuel; Plésiat, Patrick; Nordmann, Patrice

    2009-01-01

    Chromosomally encoded ß-lactamases from the Burkholderia cepacia complex species (formerly Pseudomonas cepacia) were characterized. Cloning and sequencing identified an Ambler class A ß-lactamase (PenB) from B. cenocepacia. It shares 82% amino acid identity with the PenA ß-lactamases previously identified from B. multivorans 249. Its expression was dependent upon a LysR-type regulatory protein. Its narrow-spectrum hydrolysis activity mostly included penicillins but also included expanded-spectrum cephalosporins and aztreonam at lower levels. In that study, Pen-like ß-lactamases (PenC, PenD, PenE, PenF) that shared 63 to 92% identity with PenB from B. cenocepacia were identified from other Burkholderia species. The corresponding ß-lactamase genes might be used as genetic tools for accurate Burkholderia species identification. PMID:19075063

  13. Increasing complexity: which drug class to choose for treatment of hypertension in the elderly?

    PubMed

    Kaiser, Edelgard Anna; Lotze, Ulrich; Schäfer, Hans Hendrik

    2014-01-01

    Treatment of hypertension in the elderly is expected to become more complex in the coming decades. Based on the current landscape of clinical trials, guideline recommendations remain inconclusive. The present review discusses the latest evidence derived from studies available in 2013 and investigates optimal blood pressure (BP) and preferred treatment substances. Three common archetypes are discussed that hamper the treatment of hypertension in the very elderly. In addition, this paper presents the current recommendations of the NICE 2011, JNC7 2013-update, ESH/ESC 2013, CHEP 2013, JNC8 and ASH/ISH guidelines for elderly patients. Advantages of the six main substance classes, namely diuretics, beta-blockers (BBs), calcium channel blockers (CCBs), angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), and direct renin inhibitors (DRIs) are discussed. Medical and economic implications of drug administration in the very elderly are presented. Avoidance of treatment-related adverse effects has become increasingly relevant. Current substance classes are equally effective, with similar effects on cardiovascular outcomes. Selection of substances should therefore also be based on collateral advantages of drugs that extend beyond BP reduction. The combination of ACEIs and diuretics appears to be favorable in managing systolic/diastolic hypertension. Diuretics are a preferred and cheap combination drug, and the combination with CCBs is recommended for patients with isolated systolic hypertension. ACEIs and CCBs are favorable for patients with dementia, while CCBs and ARBs imply substantial cost savings due to high adherence. PMID:24711696

  14. Glucosylation activity and complex formation of two classes of reversibly glycosylated polypeptides.

    PubMed

    Langeveld, Sandra M J; Vennik, Marco; Kottenhagen, Marijke; Van Wijk, Ringo; Buijk, Ankie; Kijne, Jan W; de Pater, Sylvia

    2002-05-01

    Reversibly glycosylated polypeptides (RGPs) have been implicated in polysaccharide biosynthesis. In plants, these proteins may function, for example, in cell wall synthesis and/or in synthesis of starch. We have isolated wheat (Triticum aestivum) and rice (Oryza sativa) Rgp cDNA clones to study the function of RGPs. Sequence comparisons showed the existence of two classes of RGP proteins, designated RGP1 and RGP2. Glucosylation activity of RGP1 and RGP2 from wheat and rice was studied. After separate expression of Rgp1 and Rgp2 in Escherichia coli or yeast (Saccharomyces cerevisiae), only RGP1 showed self-glucosylation. In Superose 12 fractions from wheat endosperm extract, a polypeptide with a molecular mass of about 40 kD is glucosylated by UDP-glucose. Transgenic tobacco (Nicotiana tabacum) plants, overexpressing either wheat Rgp1 or Rgp2, were generated. Subsequent glucosylation assays revealed that in RGP1-containing tobacco extracts as well as in RGP2-containing tobacco extracts UDP-glucose is incorporated, indicating that an RGP2-containing complex is active. Gel filtration experiments with wheat endosperm extracts and extracts from transgenic tobacco plants, overexpressing either wheat Rgp1 or Rgp2, showed the presence of RGP1 and RGP2 in high-molecular mass complexes. Yeast two-hybrid studies indicated that RGP1 and RGP2 form homo- and heterodimers. Screening of a cDNA library using the yeast two-hybrid system and purification of the complex by an antibody affinity column did not reveal the presence of other proteins in the RGP complexes. Taken together, these results suggest the presence of active RGP1 and RGP2 homo- and heteromultimers in wheat endosperm. PMID:12011358

  15. Major Histocompatibility Complex class I proteins are critical for maintaining neuronal structural complexity in the aging brain.

    PubMed

    Lazarczyk, Maciej J; Kemmler, Julia E; Eyford, Brett A; Short, Jennifer A; Varghese, Merina; Sowa, Allison; Dickstein, Daniel R; Yuk, Frank J; Puri, Rishi; Biron, Kaan E; Leist, Marcel; Jefferies, Wilfred A; Dickstein, Dara L

    2016-01-01

    Major histocompatibility complex class I (MHCI) proteins have been implicated in neuronal function through the modulation of neuritogenesis, synaptogenesis, synaptic plasticity, and memory consolidation during development. However, the involvement of MHCI in the aged brain is unclear. Here we demonstrate that MHCI deficiency results in significant dendritic atrophy along with an increase in thin dendritic spines and a reduction in stubby spines in the hippocampus of aged (12 month old) mice. Ultrastructural analyses revealed a decrease in spine head diameter and post synaptic density (PSD) area, as well as an increase in overall synapse density, and non-perforated, small spines. Interestingly, we found that the changes in synapse density and morphology appear relatively late (after the age of 6 months). Finally, we found a significant age dependent increase in the levels of the glutamate receptor, GluN2B in aged MHCI knockout mice, with no change in GluA2/3, VGluT1, PSD95 or synaptophysin. These results indicate that MHCI may be also be involved in maintaining brain integrity at post-developmental stages notably in the modulation of neuronal and spine morphology and synaptic function during non-pathological aging which could have significant implications for cognitive function. PMID:27229916

  16. Major Histocompatibility Complex class I proteins are critical for maintaining neuronal structural complexity in the aging brain

    PubMed Central

    Lazarczyk, Maciej J.; Kemmler, Julia E.; Eyford, Brett A.; Short, Jennifer A.; Varghese, Merina; Sowa, Allison; Dickstein, Daniel R.; Yuk, Frank J.; Puri, Rishi; Biron, Kaan E.; Leist, Marcel; Jefferies, Wilfred A.; Dickstein, Dara L.

    2016-01-01

    Major histocompatibility complex class I (MHCI) proteins have been implicated in neuronal function through the modulation of neuritogenesis, synaptogenesis, synaptic plasticity, and memory consolidation during development. However, the involvement of MHCI in the aged brain is unclear. Here we demonstrate that MHCI deficiency results in significant dendritic atrophy along with an increase in thin dendritic spines and a reduction in stubby spines in the hippocampus of aged (12 month old) mice. Ultrastructural analyses revealed a decrease in spine head diameter and post synaptic density (PSD) area, as well as an increase in overall synapse density, and non-perforated, small spines. Interestingly, we found that the changes in synapse density and morphology appear relatively late (after the age of 6 months). Finally, we found a significant age dependent increase in the levels of the glutamate receptor, GluN2B in aged MHCI knockout mice, with no change in GluA2/3, VGluT1, PSD95 or synaptophysin. These results indicate that MHCI may be also be involved in maintaining brain integrity at post-developmental stages notably in the modulation of neuronal and spine morphology and synaptic function during non-pathological aging which could have significant implications for cognitive function. PMID:27229916

  17. Multimodal representation contributes to the complex development of science literacy in a college biology class

    NASA Astrophysics Data System (ADS)

    Bennett, William Drew

    educators are communicating ideas and concepts to their audience with more than simple text. A focused holistic rubric was designed in this study to score how well students in this class were able to incorporate aspects of multimodality into their writing assignments. Using these scores and factors within the rubric (ex. Number of original modes created) they were correlated with classroom performance scores to determine the strength and direction of the relationship. Classroom observations of lectures and discussion sections along with personal interviews with students and teaching assistants aided the interpretation of the results. The results from the study were surprisingly complex to interpret given the background of literature which suggested a strong relationship between multimodal representations and science learning (Lemke, 2000). There were significant positive correlations between student multimodal representations and quiz scores but not exam scores. This study was also confounded by significant differences between sections at the beginning of the study which may have led to learning effects later. The dissimilarity between the tasks of writing during their homework and working on exams may be the reason for no significant correlations with exams. The power to interpret these results was limited by the number of the participants, the number of modal experiences by the students, and the operationalization of multimodal knowledge through the holistic rubric. These results do show that a relationship does exist between the similar tasks within science writing and quizzes. Students may also gain derived science literacy benefits from modal experiences on distal tasks in exams as well. This study shows that there is still much more research to be known about the interconnectedness of multimodal representational knowledge and use to the development of science literacy.

  18. A versatile class of prototype dynamical systems for complex bifurcation cascades of limit cycles

    PubMed Central

    Sándor, Bulcsú; Gros, Claudius

    2015-01-01

    A general class of prototype dynamical systems is introduced, which allows to study the generation of complex bifurcation cascades of limit cycles, including bifurcations breaking spontaneously a symmetry of the system, period doubling and homoclinic bifurcations, and transitions to chaos induced by sequences of limit cycle bifurcations. The prototype systems are adaptive, with friction forces f(V(x)) being functionally dependent exclusively on the mechanical potential V(x), characterized in turn by a finite number of local minima. We discuss several low-dimensional systems, with friction forces f(V) which are linear, quadratic or cubic polynomials in the potential V. We point out that the zeros of f(V) regulate both the relative importance of energy uptake and dissipation respectively, serving at the same time as bifurcation parameters, hence allowing for an intuitive interpretation of the overall dynamical behavior. Starting from simple Hopf- and homoclinic bifurcations, complex sequences of limit cycle bifurcations are observed when the energy uptake gains progressively in importance. PMID:26198731

  19. Structures of Staphylococcus aureus peptide deformylase in complex with two classes of new inhibitors.

    PubMed

    Lee, Sang Jae; Lee, Seung-Jae; Lee, Seung Kyu; Yoon, Hye-Jin; Lee, Hyung Ho; Kim, Kyeong Kyu; Lee, Bong Jin; Lee, Byung Il; Suh, Se Won

    2012-07-01

    Peptide deformylase (PDF) catalyzes the removal of the formyl group from the N-terminal methionine residue in newly synthesized polypeptides, which is an essential process in bacteria. Four new inhibitors of PDF that belong to two different classes, hydroxamate/pseudopeptide compounds [PMT387 (7a) and PMT497] and reverse-hydroxamate/nonpeptide compounds [PMT1039 (15e) and PMT1067], have been developed. These compounds inhibited the growth of several pathogens involved in respiratory-tract infections, such as Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae, and leading nosocomial pathogens such as Staphylococcus aureus and Klebsiella pneumoniae with a minimum inhibitory concentration (MIC) in the range 0.1-0.8 mg ml(-1). Interestingly, the reverse-hydroxamate/nonpeptide compounds showed a 250-fold higher antimicrobial activity towards S. aureus, although the four compounds showed similar K(i) values against S. aureus PDF enzymes, with K(i) values in the 11-85 nM range. To provide a structural basis for the discovery of additional PDF inhibitors, the crystal structures of S. aureus PDF in complex with the four inhibitors were determined at resolutions of 1.90-2.30 Å. The inhibitor-bound structures displayed distinct deviations depending on the inhibitor class. The distance between the Zn(2+) ion and the carbonyl O atom of the hydroxamate inhibitors (or the hydroxyl O atom of the reverse-hydroxamate inhibitors) appears to be correlated to S. aureus inhibition activity. The structural information reported in this study should aid in the discovery of new PDF inhibitors that can be used as novel antibacterial drugs. PMID:22751663

  20. Active suppression of major histocompatibility complex class II gene expression during differentiation from B cells to plasma cells.

    PubMed Central

    Latron, F; Jotterand-Bellomo, M; Maffei, A; Scarpellino, L; Bernard, M; Strominger, J L; Accolla, R S

    1988-01-01

    Constitutive expression of major histocompatibility complex class II genes is acquired very early in B-cell ontogeny and is maintained up to the B-cell blast stage. Terminal differentiation in plasma cells is, however, accompanied by a loss of class II gene expression. In B cells this gene system is under the control of several loci encoding transacting factors with activator function, one of which, the aIr-1 gene product, operates across species barriers. In this report human class II gene expression is shown to be extinguished in somatic cell hybrids between the human class II-positive B-cell line Raji and the mouse class II-negative plasmacytoma cell line P3-U1. Since all murine chromosomes are retained in these hybrids and no preferential segregation of a specific human chromosome is observed, the results are compatible with the presence of suppressor factors of mouse origin, operating across species barriers and inhibiting class II gene expression. Suppression seems to act at the level of transcription or accumulation of class II-specific mRNA, since no human, and very few murine, class II transcripts are detectable in the hybrids. Images PMID:3127829

  1. Cohesin regulates major histocompatibility complex class II genes through interactions with MHC-II insulators1

    PubMed Central

    Majumder, Parimal; Boss, Jeremy M.

    2011-01-01

    Cohesin is a multiprotein ringed complex that is most well known for its role in stabilizing the association of sister chromatids between S phase and M. More recently cohesin was found to be associated with transcriptional insulators, elements that are associated with the organization of chromatin into regulatory domains. The human major histocompatibility complex class II (MHC-II) locuscontains ten intergenic elements, termed MHC-II insulators, which bind the transcriptional insulator protein CCCTC transcription factor (CTCF). MHC-II insulators interact with each other forming a base architecture of discrete loops and potential regulatory domains. When MHC-II genes are expressed, their proximal promoter regulatory regions reorganize to the foci established by the interacting MHC-II insulators. MHC-II insulators also bind cohesin, but the functional role of cohesin in regulating this system is not known. Here we show that the binding of cohesin to MHC-II insulators occurred irrespective of MHC-II expression but was required for optimal expression of the HLA-DR and HLA-DQ genes. In a DNA dependent manner, cohesin subunits interacted with CTCF and the MHC-II specific transcription factors RFX and CIITA. Intriguingly, cohesin subunits were important for DNA looping interactions between the HLA-DRA promoter region and a 5’ MHC-II insulator but were not required for interactions between the MHC-II insulators themselves. This latter observation introduces cohesin as a regulator of MHC-II expression by initiating or stabilizing MHC-II promoter regulatory element interactions with the MHC-II insulator elements; events which are required for maximal MHC-II transcription. PMID:21911605

  2. Expression of major histocompatibility complex class II antigens in porcine leptospiral nephritis.

    PubMed

    Radaelli, E; Del Piero, F; Aresu, L; Sciarrone, F; Vicari, N; Mattiello, S; Tagliabue, S; Fabbi, M; Scanziani, E

    2009-09-01

    Class II major histocompatibility complex (MHCII) is required for the presentation of antigens to CD4 helper T cells. During nephritis, not only primary antigen presenting cells such as histiocytes and lymphocytes, but also cytokine-stimulated tubular epithelial cells express MHCII. Leptospirosis in fattening pigs is characterized by several degrees of nephritis, from absence of lesions to severe multifocal tubulo-interstitial inflammation. Renal tissue from 20 8-month-old pigs with spontaneous nephritis and 6 control pigs without renal lesions were investigated for leptospirosis by indirect immunohistochemistry (IHC) and polymerase chain reaction (PCR). IHC for MHCII also was performed on renal samples. Serum samples were tested for different serovars of Leptospira interrogans. Control pigs were free of interstitial nephritis and negative for leptospirosis by all tests. In pigs with nephritis, serology was positive for serovar Pomona in 19/20 pigs. In 16 of these 19 pigs, leptospiral renal infection was confirmed by PCR and/or indirect IHC. Nephritic lesions were classified histologically into perivascular lymphocytic (4 pigs), lymphofollicular (6 pigs), lymphohistiocytic (8 pigs), and neutrophilic (2 pigs) pattern. MHCII expression by histiocytes and lymphocytes was observed in all lesions. Prominent MHCII expression in regenerating tubular epithelium was observed in lymphofollicular and lymphohistiocytic nephritis. No tubular colocalization between leptospiral and MHCII antigen was observed. Results suggest that during leptospiral nephritis, MHCII contributes to the intensity of the inflammatory response. Furthermore de novo MHCII expression in regenerating tubules may play a role in the defence mechanism against leptospiral tubular colonization. PMID:19179617

  3. Effects of major histocompatibility complex class II knockout on mouse bone mechanical properties during development

    NASA Technical Reports Server (NTRS)

    Simske, Steven J.; Bateman, Ted A.; Smith, Erin E.; Ferguson, Virginia L.; Chapes, Stephen K.

    2002-01-01

    We investigated the effect of major histocompatibility complex class II (MHC II) knockout on the development of the mouse peripheral skeleton. These C2D mice had less skeletal development at 8, 12 and 16 weeks of age compared to wild-type C57BL/6J (B6) male mice. The C2D mice had decreased femur mechanical, geometric and compositional measurements compared to wild type mice at each of these ages. C2D femur stiffness (S), peak force in 3-pt bending (Pm), and mineral mass (Min-M) were 74%, 64% and 66%, respectively, of corresponding B6 values at 8 weeks of age. Similar differences were measured at 12 weeks (for which C2D femoral S, Pm and Min-M were 71%, 72% and 73%, respectively, of corresponding B6 values) and at 16 weeks (for which C2D femoral S, Pm and Min-M were 80%, 66% and 61%, respectively, of corresponding B6 values). MHC II knockout delays the development of adult bone properties and is accompanied by lower body mass compared to wild-type controls.

  4. Diversity at the major histocompatibility complex Class II in the platypus, Ornithorhynchus anatinus.

    PubMed

    Lillie, Mette; Woodward, Rachael E; Sanderson, Claire E; Eldridge, Mark D B; Belov, Katherine

    2012-07-01

    The platypus (Ornithorhynchus anatinus) is the sole survivor of a previously widely distributed and diverse lineage of ornithorhynchid monotremes. Its dependence on healthy water systems imposes an inherent sensitivity to habitat degradation and climate change. Here, we compare genetic diversity at the major histocompatibility complex (MHC) Class II-DZB gene and 3 MHC-associated microsatellite markers with diversity at 6 neutral microsatellite markers in 70 platypuses from across their range, including the mainland of Australia and the isolated populations of Tasmania, King Island, and Kangaroo Island. Overall, high DZB diversity was observed in the platypus, with 57 DZB β1 alleles characterized. Significant positive selection was detected within the DZB peptide-binding region, promoting variation in this domain. Low levels of genetic diversity were detected at all markers in the 2 island populations, King Island (endemic) and Kangaroo Island (introduced), with the King Island platypuses monomorphic at the DZB locus. Loss of MHC diversity on King Island is of concern, as the population may have compromised immunological fitness and reduced ability to resist changing environmental conditions. PMID:22563128

  5. Effects of major histocompatibility complex class II knockout on mouse bone mechanical properties during development.

    PubMed

    Simske, Steven J; Bateman, Ted A; Smith, Erin E; Ferguson, Virginia L; Chapes, Stephen K

    2002-01-01

    We investigated the effect of major histocompatibility complex class II (MHC II) knockout on the development of the mouse peripheral skeleton. These C2D mice had less skeletal development at 8, 12 and 16 weeks of age compared to wild-type C57BL/6J (B6) male mice. The C2D mice had decreased femur mechanical, geometric and compositional measurements compared to wild type mice at each of these ages. C2D femur stiffness (S), peak force in 3-pt bending (Pm), and mineral mass (Min-M) were 74%, 64% and 66%, respectively, of corresponding B6 values at 8 weeks of age. Similar differences were measured at 12 weeks (for which C2D femoral S, Pm and Min-M were 71%, 72% and 73%, respectively, of corresponding B6 values) and at 16 weeks (for which C2D femoral S, Pm and Min-M were 80%, 66% and 61%, respectively, of corresponding B6 values). MHC II knockout delays the development of adult bone properties and is accompanied by lower body mass compared to wild-type controls. PMID:12085652

  6. Persistent Ehrlichia chaffeensis infection occurs in the absence of functional major histocompatibility complex class II genes

    NASA Technical Reports Server (NTRS)

    Ganta, Roman Reddy; Wilkerson, Melinda J.; Cheng, Chuanmin; Rokey, Aaron M.; Chapes, Stephen K.

    2002-01-01

    Human monocytic ehrlichiosis is an emerging tick-borne disease caused by the rickettsia Ehrlichia chaffeensis. We investigated the impact of two genes that control macrophage and T-cell function on murine resistance to E. chaffeensis. Congenic pairs of wild-type and toll-like receptor 4 (tlr4)- or major histocompatibility complex class II (MHC-II)-deficient mice were used for these studies. Wild-type mice cleared the infection within 2 weeks, and the response included macrophage activation and the synthesis of E. chaffeensis-specific Th1-type immunoglobulin G response. The absence of a functional tlr4 gene depressed nitric oxide and interleukin 6 secretion by macrophages and resulted in short-term persistent infections for > or =30 days. In the absence of MHC-II alleles, E. chaffeensis infections persisted throughout the entire 3-month evaluation period. Together, these data suggest that macrophage activation and cell-mediated immunity, orchestrated by CD4(+) T cells, are critical for conferring resistance to E. chaffeensis.

  7. T cell receptor recognition of a 'super-bulged' major histocompatibility complex class I-bound peptide

    SciTech Connect

    Tynan, Fleur E; Burrows, Scott R; Buckle, Ashley M; Clements, Craig S; Borg, Natalie A; Miles, John J; Beddoe, Travis; Whisstock, James C; Wilce, Matthew C; Silins, Sharon L; Burrows, Jacqueline M; Kjer-Nielsen, Lars; Kostenko, Lyudmila; Purcell, Anthony W; McCluskey, James; Rossjohn, Jamie

    2010-07-20

    Unusually long major histocompatibility complex (MHC) class I-restricted epitopes are important in immunity, but their 'bulged' conformation represents a potential obstacle to {alpha}{beta} T cell receptor (TCR)-MHC class I docking. To elucidate how such recognition is achieved while still preserving MHC restriction, we have determined here the structure of a TCR in complex with HLA-B*3508 presenting a peptide 13 amino acids in length. This complex was atypical of TCR-peptide-MHC class I interactions, being dominated at the interface by peptide-mediated interactions. The TCR assumed two distinct orientations, swiveling on top of the centrally bulged, rigid peptide such that only limited contacts were made with MHC class I. Although the TCR-peptide recognition resembled an antibody-antigen interaction, the TCR-MHC class I contacts defined a minimal 'generic footprint' of MHC-restriction. Thus our findings simultaneously demonstrate the considerable adaptability of the TCR and the 'shape' of MHC restriction.

  8. Major histocompatibility complex class II genetic variation in forest musk deer (Moschus berezovskii) in China.

    PubMed

    Yao, Gang; Zhu, Ying; Wan, Qiu-Hong; Fang, Sheng-Guo

    2015-10-01

    The major histocompatibility complex (MHC) plays an important role in the immune system of vertebrates. We used the second exon of four MHC class II genes (DRA, DQA1, DQA2 and DRB3) to assess the overall MHC variation in forest musk deer (Moschus berezovskii). We also compared the MHC variation in captive and wild populations. We observed 22 alleles at four loci (four at DRA, four at DQA1, four at DQA2 and 10 at DRB3), 15 of which were newly identified alleles. Results suggest that forest musk deer maintain relatively high MHC variation, which may result from balancing selection. Moreover, considerable diversity was observed at the DRA locus. We found a high frequency of Mobe-DRA*02, Mobe-DQA1*01 and Mobe-DQA2*05 alleles, which may be important for pathogen resistance. A Ewens-Watterson test showed that the DRB3 locus in the wild population had experienced recent balancing selection. We detected a small divergence at the DRA locus, suggesting the effect of weak positive selection on the DRA gene. Alternatively, this locus may be young and not yet adapted a wide spectrum of alleles for pathogen resistance. The significant heterozygosity deficit observed at the DQA1 and DRB3 loci in the captive population and at all four loci in the wild population may be the result of a population bottleneck. Additionally, MHC genetic diversity was higher in the wild population than in the captive, suggesting that the wild population may have the ability to respond to a wider range of pathogens. PMID:26370614

  9. Characterisation of major histocompatibility complex class I genes at the fetal-maternal interface of marsupials.

    PubMed

    Buentjen, Ina; Drews, Barbara; Frankenberg, Stephen R; Hildebrandt, Thomas B; Renfree, Marilyn B; Menzies, Brandon R

    2015-07-01

    Major histocompatibility complex class I molecules (MHC-I) are expressed at the cell surface and are responsible for the presentation of self and non-self antigen repertoires to the immune system. Eutherian mammals express both classical and non-classical MHC-I molecules in the placenta, the latter of which are thought to modulate the maternal immune response during pregnancy. Marsupials last shared a common ancestor with eutherian mammals such as humans and mice over 160 million years ago. Since, like eutherians, they have an intra-uterine development dependent on a placenta, albeit a short-lived and less invasive one, they provide an opportunity to investigate the evolution of MHC-I expression at the fetal-maternal interface. We have characterised MHC-I mRNA expression in reproductive tissues of the tammar wallaby (Macropus eugenii) from the time of placental attachment to day 25 of the 26.5 day pregnancy. Putative classical MHC-I genes were expressed in the choriovitelline placenta, fetus, and gravid endometrium throughout the whole of this period. The MHC-I classical sequences were phylogenetically most similar to the Maeu-UC (50/100 clones) and Maeu-UA genes (7/100 clones). Expression of three non-classical MHC-I genes (Maeu-UD, Maeu-UK and Maeu-UM) were also present in placental samples. The results suggest that expression of classical and non-classical MHC-I genes in extant marsupial and eutherian mammals may have been necessary for the evolution of the ancestral therian placenta and survival of the mammalian fetus at the maternal-fetal interface. PMID:25957041

  10. Regulation of a bovine nonclassical major histocompatibility complex class I gene promoter.

    PubMed

    O'Gorman, Grace M; Al Naib, Abdullah; Naib, Abdullah Al; Ellis, Shirley A; Mamo, Solomon; O'Doherty, Alan M; Lonergan, Pat; Fair, Trudee

    2010-08-01

    Studies have shown in humans and other species that the major histocompatibility complex class I (MHC-I) region is involved at a number of levels in the establishment and maintenance of pregnancy. The aim of this study was to characterize how a bovine nonclassical MHC-I gene (NC1) is regulated. Initial serial deletion experiments of a 2-kb fragment of the NC1 promoter identified regions with positive regulatory elements in the proximal promoter and evidence for a silencer module(s) further upstream that cooperatively contributed to constitutive NC1 expression. The cytokines interferon tau (IFNT), interferon gamma (IFNG), and interleukin 4 (IL4) significantly increased luciferase expression in NC1 promoter reporter constructs and endogenous NC1 mRNA levels in a bovine endometrial cell line. In addition, IFNG, IL3, IL4, and progesterone significantly increased Day 7 bovine blastocyst NC1 mRNA expression when supplemented during in vitro embryo culture. Site-directed mutagenesis analysis identified a STAT6 binding site that conferred IL4 responsiveness in the NC1 proximal promoter. Furthermore, methylation treatment of the proximal promoter, which contains a CpG island, completely abrogated constitutive NC1 expression. Overall, the findings presented here suggest that constitutive NC1 expression is regulated positively by elements in the proximal promoter, which are further controlled by upstream silencer modules. The promoter is responsive to IFNT, IFNG, and IL4, suggesting possible roles for these cytokines in bovine preimplantation embryo survival and/or maternal-fetal tolerance. Our studies also suggest that methylation of the proximal promoter, in particular, could play a significant role in regulating NC1 expression. PMID:20427761

  11. Remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions.

    PubMed

    Jönsson, Peter; Southcombe, Jennifer H; Santos, Ana Mafalda; Huo, Jiandong; Fernandes, Ricardo A; McColl, James; Lever, Melissa; Evans, Edward J; Hudson, Alexander; Chang, Veronica T; Hanke, Tomáš; Godkin, Andrew; Dunne, Paul D; Horrocks, Mathew H; Palayret, Matthieu; Screaton, Gavin R; Petersen, Jan; Rossjohn, Jamie; Fugger, Lars; Dushek, Omer; Xu, Xiao-Ning; Davis, Simon J; Klenerman, David

    2016-05-17

    The αβ T-cell coreceptor CD4 enhances immune responses more than 1 million-fold in some assays, and yet the affinity of CD4 for its ligand, peptide-major histocompatibility class II (pMHC II) on antigen-presenting cells, is so weak that it was previously unquantifiable. Here, we report that a soluble form of CD4 failed to bind detectably to pMHC II in surface plasmon resonance-based assays, establishing a new upper limit for the solution affinity at 2.5 mM. However, when presented multivalently on magnetic beads, soluble CD4 bound pMHC II-expressing B cells, confirming that it is active and allowing mapping of the native coreceptor binding site on pMHC II. Whereas binding was undetectable in solution, the affinity of the CD4/pMHC II interaction could be measured in 2D using CD4- and adhesion molecule-functionalized, supported lipid bilayers, yielding a 2D Kd of ∼5,000 molecules/μm(2) This value is two to three orders of magnitude higher than previously measured 2D Kd values for interacting leukocyte surface proteins. Calculations indicated, however, that CD4/pMHC II binding would increase rates of T-cell receptor (TCR) complex phosphorylation by threefold via the recruitment of Lck, with only a small, 2-20% increase in the effective affinity of the TCR for pMHC II. The affinity of CD4/pMHC II therefore seems to be set at a value that increases T-cell sensitivity by enhancing phosphorylation, without compromising ligand discrimination. PMID:27114505

  12. NetMHCcons: a consensus method for the major histocompatibility complex class I predictions.

    PubMed

    Karosiene, Edita; Lundegaard, Claus; Lund, Ole; Nielsen, Morten

    2012-03-01

    A key role in cell-mediated immunity is dedicated to the major histocompatibility complex (MHC) molecules that bind peptides for presentation on the cell surface. Several in silico methods capable of predicting peptide binding to MHC class I have been developed. The accuracy of these methods depends on the data available characterizing the binding specificity of the MHC molecules. It has, moreover, been demonstrated that consensus methods defined as combinations of two or more different methods led to improved prediction accuracy. This plethora of methods makes it very difficult for the non-expert user to choose the most suitable method for predicting binding to a given MHC molecule. In this study, we have therefore made an in-depth analysis of combinations of three state-of-the-art MHC-peptide binding prediction methods (NetMHC, NetMHCpan and PickPocket). We demonstrate that a simple combination of NetMHC and NetMHCpan gives the highest performance when the allele in question is included in the training and is characterized by at least 50 data points with at least ten binders. Otherwise, NetMHCpan is the best predictor. When an allele has not been characterized, the performance depends on the distance to the training data. NetMHCpan has the highest performance when close neighbours are present in the training set, while the combination of NetMHCpan and PickPocket outperforms either of the two methods for alleles with more remote neighbours. The final method, NetMHCcons, is publicly available at www.cbs.dtu.dk/services/NetMHCcons , and allows the user in an automatic manner to obtain the most accurate predictions for any given MHC molecule. PMID:22009319

  13. Disruption of Hydrogen Bonds between Major Histocompatibility Complex Class II and the Peptide N-Terminus Is Not Sufficient to Form a Human Leukocyte Antigen-DM Receptive State of Major Histocompatibility Complex Class II

    PubMed Central

    Schulze, Monika-Sarah E. D.; Anders, Anne-Kathrin; Sethi, Dhruv K.; Call, Melissa J.

    2013-01-01

    Peptide presentation by MHC class II is of critical importance to the function of CD4+ T cells. HLA-DM resides in the endosomal pathway and edits the peptide repertoire of newly synthesized MHC class II molecules before they are exported to the cell surface. HLA-DM ensures MHC class II molecules bind high affinity peptides by targeting unstable MHC class II:peptide complexes for peptide exchange. Research over the past decade has implicated the peptide N-terminus in modulating the ability of HLA-DM to target a given MHC class II:peptide combination. In particular, attention has been focused on both the hydrogen bonds between MHC class II and peptide, and the occupancy of the P1 anchor pocket. We sought to solve the crystal structure of a HLA-DR1 molecule containing a truncated hemagglutinin peptide missing three N-terminal residues compared to the full-length sequence (residues 306–318) to determine the nature of the MHC class II:peptide species that binds HLA-DM. Here we present structural evidence that HLA-DR1 that is loaded with a peptide truncated to the P1 anchor residue such that it cannot make select hydrogen bonds with the peptide N-terminus, adopts the same conformation as molecules loaded with full-length peptide. HLA-DR1:peptide combinations that were unable to engage up to four key hydrogen bonds were also unable to bind HLA-DM, while those truncated to the P2 residue bound well. These results indicate that the conformational changes in MHC class II molecules that are recognized by HLA-DM occur after disengagement of the P1 anchor residue. PMID:23976922

  14. Multimodal Representation Contributes to the Complex Development of Science Literacy in a College Biology Class

    ERIC Educational Resources Information Center

    Bennett, William Drew

    2011-01-01

    This study is an investigation into the science literacy of college genetics students who were given a modified curriculum to address specific teaching and learning problems from a previous class. This study arose out of an interest by the professor and researcher to determine how well students in the class Human Genetics in the 21st Century…

  15. Economies of Racism: Grounding Education Policy Research in the Complex Dialectic of Race, Class, and Capital

    ERIC Educational Resources Information Center

    Brown, Anthony L.; De Lissovoy, Noah

    2011-01-01

    The intent of this paper is to interrogate the current theoretical discourse in education concerning issues of race and class. The authors maintain that in recent years educational theory and critical policy discourse have unintentionally become splintered in such a way that race and class theories are employed separately, without much analysis of…

  16. The 1.4 Å Crystal Structure of the Class D [beta]-Lactamase OXA-1 Complexed with Doripenem

    SciTech Connect

    Schneider, Kyle D.; Karpen, Mary E.; Bonomo, Robert A.; Leonard, David A.; Powers, Rachel A.

    2010-01-12

    The clinical efficacy of carbapenem antibiotics depends on their resistance to the hydrolytic action of {beta}-lactamase enzymes. The structure of the class D {beta}-lactamase OXA-1 as an acyl complex with the carbapenem doripenem was determined to 1.4 {angstrom} resolution. Unlike most class A and class C carbapenem complexes, the acyl carbonyl oxygen in the OXA-1-doripenem complex is bound in the oxyanion hole. Interestingly, no water molecules were observed in the vicinity of the acyl linkage, providing an explanation for why carbapenems inhibit OXA-1. The side chain amine of K70 remains fully carboxylated in the acyl structure, and the resulting carbamate group forms a hydrogen bond to the alcohol of the 6{alpha}-hydroxyethyl moiety of doripenem. The carboxylate attached to the {beta}-lactam ring of doripenem is stabilized by a salt bridge to K212 and a hydrogen bond with T213, in lieu of the interaction with an arginine side chain found in most other {beta}-lactamase-{beta}-lactam complexes (e.g., R244 in the class A member TEM-1). This novel set of interactions with the carboxylate results in a major shift of the carbapenem's pyrroline ring compared to the structure of the same ring in meropenem bound to OXA-13. Additionally, bond angles of the pyrroline ring suggest that after acylation, doripenem adopts the {Delta}{sup 1} tautomer. These findings provide important insights into the role that carbapenems may have in the inactivation process of class D {beta}-lactamases.

  17. Enriched HLA-DQ3 phenotype and decreased class I major histocompatibility complex antigen expression in recurrent respiratory papillomatosis.

    PubMed Central

    Bonagura, V R; Siegal, F P; Abramson, A L; Santiago-Schwarz, F; O'Reilly, M E; Shah, K; Drake, D; Steinberg, B M

    1994-01-01

    Respiratory papillomas, caused by human papillomaviruses, are benign tumors that recur following removal. We evaluated immune function and major histocompatibility complex (MHC) phenotype and expression in these patients. MHC-independent immune function appeared normal. The frequency of peripheral blood MHC class II phenotypes was highly enriched for DQ3 and DR11, one split of DR5. Class I MHC antigen expression on papilloma tissue was markedly reduced. Together, these phenomena may facilitate papillomavirus evasion of the cellular immune response. Images PMID:7496977

  18. Identification of the class I genes of the mouse major histocompatibility complex by DNA-mediated gene transfer.

    PubMed

    Goodenow, R S; McMillan, M; Nicolson, M; Sher, B T; Eakle, K; Davidson, N; Hood, L

    1982-11-18

    DNA-mediated gene transfer was used to identify cloned class I genes from the major histocompatibility complex of the BALB/c mouse. Three genes encoding the transplantation antigens H-2 Kd, Dd and Ld were identified as well as genes encoding the Qa-2,3 and two TL differentiation antigens. As many as 10 putative novel class I genes were detected by the association of their gene products with beta 2-microglobulin. Alloantiserum prepared to one of the novel antigens was used to demonstrate the expression of the previously undetected antigen on spleen cells of various inbred, congeneic, and recombinant congeneic strains of mice. PMID:6815535

  19. Hsp90-peptide complexes stimulate antigen presentation through the class II pathway after binding scavenger receptor SREC-I

    PubMed Central

    Murshid, Ayesha; Gong, Jianlin; Calderwood, Stuart K

    2016-01-01

    Molecular chaperones such as heat shock protein 90 (Hsp90) have been shown to form complexes with tumor antigens and can be used to prepare anticancer vaccines largely due to this property. Earlier studies had suggested that, mice immunized with a molecular chaperone based vaccine derived from tumors became immune to further vaccination and that both CD8+ and CD4+ T cells were activated by the chaperone vaccine in a manner dependent on scavenger receptor SREC-I. Here we have investigated mechanisms whereby SREC-I might facilitate uptake of Hsp90 conjugated peptides by APC into the MHC class II pathway for presentation to CD4+ T cells. Our studies showed that antigenic peptides associated with Hsp90 were taken up into the Class II pathway by a mechanism dependent on SREC-I binding and internalization and presented to CD4+ T cells. In addition our studies showed that SREC-I could associate with MHC class II molecules on the cell surface and in intracellular endosomes, suggesting a mechanism involving facilitated uptake of peptides into the MHC class II pathway. These studies in addition to our earlier findings showed SREC-I to play a primary role in chaperone-associated antigen uptake both through cross priming of MHC class I molecules and entry into the class II pathway. PMID:25155057

  20. Crystal structures of an archaeal class II DNA photolyase and its complex with UV-damaged duplex DNA.

    PubMed

    Kiontke, Stephan; Geisselbrecht, Yann; Pokorny, Richard; Carell, Thomas; Batschauer, Alfred; Essen, Lars-Oliver

    2011-11-01

    Class II photolyases ubiquitously occur in plants, animals, prokaryotes and some viruses. Like the distantly related microbial class I photolyases, these enzymes repair UV-induced cyclobutane pyrimidine dimer (CPD) lesions within duplex DNA using blue/near-UV light. Methanosarcina mazei Mm0852 is a class II photolyase of the archaeal order of Methanosarcinales, and is closely related to plant and metazoan counterparts. Mm0852 catalyses light-driven DNA repair and photoreduction, but in contrast to class I enzymes lacks a high degree of binding discrimination between UV-damaged and intact duplex DNA. We solved crystal structures of Mm0852, the first one for a class II photolyase, alone and in complex with CPD lesion-containing duplex DNA. The lesion-binding mode differs from other photolyases by a larger DNA-binding site, and an unrepaired CPD lesion is found flipped into the active site and recognized by a cluster of five water molecules next to the bound 3'-thymine base. Different from other members of the photolyase-cryptochrome family, class II photolyases appear to utilize an unusual, conserved tryptophane dyad as electron transfer pathway to the catalytic FAD cofactor. PMID:21892138

  1. Structure and Function of Cross-class Complexes of G Protein-coupled Secretin and Angiotensin 1a Receptors.

    PubMed

    Harikumar, Kaleeckal G; Augustine, Mary Lou; Lee, Leo T O; Chow, Billy K C; Miller, Laurence J

    2016-08-12

    Complexes of secretin (SecR) and angiotensin 1a (Atr1a) receptors have been proposed to be functionally important in osmoregulation, providing an explanation for overlapping and interdependent functions of hormones that bind and activate different classes of GPCRs. However, the nature of these cross-class complexes has not been well characterized and their signaling properties have not been systematically explored. We now use competitive inhibition of receptor bioluminescence resonance energy transfer and bimolecular fluorescence complementation to establish the dominant functionally important state as a symmetrical homodimeric form of SecR decorated by monomeric Atr1a, interacting through lipid-exposed faces of Atr1a TM1 and TM4. Conditions increasing prevalence of this complex exhibited negative allosteric modulatory impact on secretin-stimulated cAMP responses at SecR. In contrast, activating Atr1a with full agonist in such a complex exhibited a positive allosteric modulatory impact on the same signaling event. This modulation was functionally biased, with secretin-stimulated calcium responses unaffected, whereas angiotensin-stimulated calcium responses through the complex were reduced or absent. Further supporting this interpretation, Atr1a with mutations of lipid-exposed faces of TM1 and TM4 that did not affect its ability to bind or signal, could be expressed in the same cell as SecR, yet not exhibit either the negative or positive allosteric impact on cAMP observed with the inactive or activated states of wild type Atr1a on function, and not interfere with angiotensin-stimulated calcium responses like complexes with Atr1a. This may provide a more selective means of exploring the physiologic functional impact of this cross-class receptor complex without interfering with the function of either component receptor. PMID:27330080

  2. The Thermodynamic Mechanism of Peptide–MHC Class II Complex Formation Is a Determinant of Susceptibility to HLA-DM

    PubMed Central

    Templeton, Megan; Hoffman, Megan; Castellini, Margaret J.

    2015-01-01

    Peptides bind MHC class II molecules through a thermodynamically nonadditive process consequent to the flexibility of the reactants. Currently, how the specific outcome of this binding process affects the ensuing epitope selection needs resolution. Calorimetric assessment of binding thermodynamics for hemagglutinin 306–319 peptide variants to the human MHC class II HLA-DR1 (DR1) and a mutant DR1 reveals that peptide/DR1 complexes can be formed with different enthalpic and entropic contributions. Complexes formed with a smaller entropic penalty feature circular dichroism spectra consistent with a non–compact form, and molecular dynamics simulation shows a more flexible structure. The opposite binding mode, compact and less flexible, is associated with greater entropic penalty. These structural variations are associated with rearrangements of residues known to be involved in HLA-DR (DM) binding, affinity of DM for the complex, and complex susceptibility to DM-mediated peptide exchange. Thus, the thermodynamic mechanism of peptide binding to DR1 correlates with the structural rigidity of the complex, and DM mediates peptide exchange by “sensing” flexible complexes in which the aforementioned residues are rearranged at a higher frequency than in more rigid ones. PMID:26116504

  3. Zinc Induces Dimerization of the Class II Major Histocompatibility Complex Molecule That Leads to Cooperative Binding to a Superantigen

    SciTech Connect

    Li,H.; Zhao, Y.; Guo, Y.; Li, Z.; Eislele, L.; Mourad, W.

    2007-01-01

    Dimerization of class II major histocompatibility complex (MHC) plays an important role in the MHC biological function. Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen that can activate large fractions of T cells bearing specific T cell receptor V{beta} elements. Here we have used structural, sedimentation, and surface plasmon resonance detection approaches to investigate the molecular interactions between MAM and the class II MHC molecule HLA-DR1 in the context of a hemagglutinin peptide-(306-318) (HA). Our results revealed that zinc ion can efficiently induce the dimerization of the HLA-DR1/HA complex. Because the crystal structure of the MAM/HLA-DR1/hemagglutinin complex in the presence of EDTA is nearly identical to the structure of the complex crystallized in the presence of zinc ion, Zn{sup 2+} is evidently not directly involved in the binding between MAM and HLA-DR1. Sedimentation and surface plasmon resonance studies further revealed that MAM binds the HLA-DR1/HA complex with high affinity in a 1:1 stoichiometry, in the absence of Zn{sup 2+}. However, in the presence of Zn{sup 2+}, a dimerized MAM/HLA-DR1/HA complex can arise through the Zn{sup 2+}-induced DR1 dimer. In the presence of Zn{sup 2+}, cooperative binding of MAM to the DR1 dimer was also observed.

  4. Major histocompatibility complex haplotypes and class II genes in non-Jewish patients with pemphigus vulgaris.

    PubMed Central

    Ahmed, A R; Wagner, R; Khatri, K; Notani, G; Awdeh, Z; Alper, C A; Yunis, E J

    1991-01-01

    Previous studies demonstrated that HLA-DR4 was markedly increased among Ashkenazi Jewish patients with pemphigus vulgaris (PV), almost entirely as the common Jewish extended haplotype [HLA-B38, SC21, DR4, DQw8] or as the haplotype HLA-B35, SC31, DR4, DQw8, and that HLA-DR4, DQw8 was distributed among patients in a manner consistent with dominant expression of a class II (D-region or D-region-linked) susceptibility gene. In the present study of major histocompatibility complex (MHC) haplotypes in 25 non-Jewish PV patients, DR4, DQw8 was found in 12 of the patients and DRw6, DQw5 was found in 15. Only 3 patients had neither. Only 1 of the DR4, DQw8 haplotypes was [HLA-B38, SC21, DR4, DQw8] and 2 were HLA-B35, SC31, DR4, DQw8; most were the presumed fragments (SC31, DR4, DQw8) or (SC21, DR4, DQw8) or DR4, DQw8 with some other complotype. Of the patients with DRw6, DQw5, all were DRw14, DQw5, and 6 had a rare Caucasian haplotype, HLA-Bw55, SB45, DRw14, DQw5. Four of 6 of these were found in patients of Italian extraction, as was the 1 normal example. The non-Jewish patients were of more Southern European extraction than our controls. This suggests that there are two major MHC susceptibility alleles in American patients with PV. The more ancient apparently arose on a haplotype in the Jews, HLA-B38(35), SC21(SC31), DR4, DQw8, and spread to other populations largely as D-region segments. The other arose in or near Italy on the haplotype HLA-Bw55, SB45, DRw14, DQw5 and has also partially fragmented so that many patients carry only DRw14, DQw5. The available data do not permit the specific localization of either the DR4, DQw8- or the DRw14, DQw5-linked susceptibility genes. Images PMID:1675792

  5. Improving the prediction accuracy of protein structural class: approached with alternating word frequency and normalized Lempel-Ziv complexity.

    PubMed

    Zhang, Shengli; Liang, Yunyun; Yuan, Xiguo

    2014-01-21

    Prediction of protein structural class for low-similarity sequences remains a challenging problem. In this study, the new computational method has been developed to predict protein structural class by incorporating alternating word frequency and normalized Lempel-Ziv complexity. To evaluate the performance of the proposed method, jackknife cross-validation tests are performed on three widely used benchmark datasets, 25PDB, 1189 and 640, respectively. We report 83.6%, 81.8% and 83.6% prediction accuracies for 25PDB, 1189 and 640 benchmarks, respectively. Comparison of our results with other methods shows that the proposed method is very promising and may provide a cost-effective alternative to predict protein structural class in particular for low-similarity datasets and may at least play an important complementary role to existing methods. PMID:24140787

  6. Organization and characteristics of the major histocompatibility complex class II region in the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis).

    PubMed

    Ruan, Rui; Ruan, Jue; Wan, Xiao-Ling; Zheng, Yang; Chen, Min-Min; Zheng, Jin-Song; Wang, Ding

    2016-01-01

    Little is known about the major histocompatibility complex (MHC) in the genome of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) (YFP) or other cetaceans. In this study, a high-quality YFP bacterial artificial chromosome (BAC) library was constructed. We then determined the organization and characterization of YFP MHC class II region by screening the BAC library, followed by sequencing and assembly of positive BAC clones. The YFP MHC class II region consists of two segregated contigs (218,725 bp and 328,435 bp respectively) that include only eight expressed MHC class II genes, three pseudo MHC genes and twelve non-MHC genes. The YFP has fewer MHC class II genes than ruminants, showing locus reduction in DRB, DQA, DQB, and loss of DY. In addition, phylogenic and evolutionary analyses indicated that the DRB, DQA and DQB genes might have undergone birth-and-death evolution, whereas the DQB gene might have evolved under positive selection in cetaceans. These findings provide an essential foundation for future work, such as estimating MHC genetic variation in the YFP or other cetaceans. This work is the first report on the MHC class II region in cetaceans and offers valuable information for understanding the evolution of MHC genome in cetaceans. PMID:26932528

  7. 'You were not born here, so you are classless, you are free!' Social class and cultural complex in analysis.

    PubMed

    Kiehl, Emilija

    2016-09-01

    The unconscious impact of differences in culture and social class is discussed from the perspective of an analyst practising in London whose 'foreign accent' prevents patients from placing her within the social stratifications by which they feel confined. Because she is seen by them as an analyst from both 'inside' and 'outside' the British psycho-social fabric and cultural complex, this opens a space in the transference that enables fuller exploration of the impact of the British social class system on patients' experience of themselves and their world. The paper considers this impact as a trans-generational trauma of living in a society of sharp socio-economic divisions based on material property. This is illustrated with the example of a patient who, at the point of moving towards the career to which he aspired, was unable to separate a sense of personal identity from the social class he so desperately wanted to leave behind and walk the long avenue of individuation. The dearth of literature on the subject of class is considered, and the paper concludes that not enough attention is given to class identification in training. PMID:27530168

  8. Organization and characteristics of the major histocompatibility complex class II region in the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis)

    PubMed Central

    Ruan, Rui; Ruan, Jue; Wan, Xiao-Ling; Zheng, Yang; Chen, Min-Min; Zheng, Jin-Song; Wang, Ding

    2016-01-01

    Little is known about the major histocompatibility complex (MHC) in the genome of Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) (YFP) or other cetaceans. In this study, a high-quality YFP bacterial artificial chromosome (BAC) library was constructed. We then determined the organization and characterization of YFP MHC class II region by screening the BAC library, followed by sequencing and assembly of positive BAC clones. The YFP MHC class II region consists of two segregated contigs (218,725 bp and 328,435 bp respectively) that include only eight expressed MHC class II genes, three pseudo MHC genes and twelve non-MHC genes. The YFP has fewer MHC class II genes than ruminants, showing locus reduction in DRB, DQA, DQB, and loss of DY. In addition, phylogenic and evolutionary analyses indicated that the DRB, DQA and DQB genes might have undergone birth-and-death evolution, whereas the DQB gene might have evolved under positive selection in cetaceans. These findings provide an essential foundation for future work, such as estimating MHC genetic variation in the YFP or other cetaceans. This work is the first report on the MHC class II region in cetaceans and offers valuable information for understanding the evolution of MHC genome in cetaceans. PMID:26932528

  9. Two putative subunits of a peptide pump encoded in the human major histocompatability complex class 2 region

    SciTech Connect

    Bahram, S.; Arnold, D.; Bresnahan, M.; Strominger, J.L.; Spies, T. )

    1991-11-15

    The class 2 region of the human major histocompatibility complex (MHC) may encode several genes controlling the processing of endogenous antigen and the presentation of peptide epitopes by MHC class 1 molecules to cytotoxic T lymphocytes. A previously described peptide supply factor (PSF1) is a member of the multidrug-resistance family of transporters and may pump cytosolic peptides into the membrane-bound compartment where class 1 molecules assemble. A second transporter gene, PSF2, was identified 10 kilobases (kb) from PSF1, near the class 2 DOB gene. The complete sequences of PSF1 and PSF2 were determined from cDNA clones. The translation products are closely related in sequence and predicted secondary structure. Both contain a highly conserved ATP-binding fold and share 25% homology in a hydrophobic domain with a tentative number of eight membrane-spanning segments. Based on the principle dimeric organization of these two domains in other transporters, PSF1 and PSF2 may function as complementary subunits, independently as homodimers, or both. Taken together with previous genetic evidence, the coregulation of PSF1 and PSF2 by {gamma} interferon and the to-some-degree coordinate transcription of these genes suggest a common role in peptide-loading of class 1 molecules, although a distinct function of PSF2 cannot be ruled out.

  10. Selection and trans-species polymorphism of major histocompatibility complex class II genes in the order Crocodylia.

    PubMed

    Jaratlerdsiri, Weerachai; Isberg, Sally R; Higgins, Damien P; Miles, Lee G; Gongora, Jaime

    2014-01-01

    Major Histocompatibility Complex (MHC) class II genes encode for molecules that aid in the presentation of antigens to helper T cells. MHC characterisation within and between major vertebrate taxa has shed light on the evolutionary mechanisms shaping the diversity within this genomic region, though little characterisation has been performed within the Order Crocodylia. Here we investigate the extent and effect of selective pressures and trans-species polymorphism on MHC class II α and β evolution among 20 extant species of Crocodylia. Selection detection analyses showed that diversifying selection influenced MHC class II β diversity, whilst diversity within MHC class II α is the result of strong purifying selection. Comparison of translated sequences between species revealed the presence of twelve trans-species polymorphisms, some of which appear to be specific to the genera Crocodylus and Caiman. Phylogenetic reconstruction clustered MHC class II α sequences into two major clades representing the families Crocodilidae and Alligatoridae. However, no further subdivision within these clades was evident and, based on the observation that most MHC class II α sequences shared the same trans-species polymorphisms, it is possible that they correspond to the same gene lineage across species. In contrast, phylogenetic analyses of MHC class II β sequences showed a mixture of subclades containing sequences from Crocodilidae and/or Alligatoridae, illustrating orthologous relationships among those genes. Interestingly, two of the subclades containing sequences from both Crocodilidae and Alligatoridae shared specific trans-species polymorphisms, suggesting that they may belong to ancient lineages pre-dating the divergence of these two families from the common ancestor 85-90 million years ago. The results presented herein provide an immunogenetic resource that may be used to further assess MHC diversity and functionality in Crocodylia. PMID:24503938

  11. Major histocompatibility complex class II A genes in cichlid fishes: identification, expression, linkage relationships, and haplotype variation.

    PubMed

    Murray, B W; Shintani, S; Sültmann, H; Klein, J

    2000-06-01

    Two cichlid species, the haplochromine Aulonocara hansbaenschi and the tilapiine Oreochromis niloticus, were used to study the major histocompatibility complex (Mhc) class II A variation within this group. Multiple class II A sequences were recovered from A. hansbaenschi and O. niloticus cDNA libraries and three sequence families, DAA, DBA, and DCA, were identified. Sets of O. niloticus haploid embryo families were used to determine the linkage relationships of these genes. Two independently assorting linkage groups were detected, DAA and DBA/DCA, neither of which is linked to the previously described Mhc class I gene cluster. Three DCA genes and up to four DBA genes were found to segregate in different haplotypes, whereas DAA occurred as a single locus. Four DBA haplotypes, DBA*H1-H4, were identified and shown to co-segregate with the previously described class II B haplotypes. Four DCA haplotypes, DCA*H1-H4, were found at a distance of 37 cM from the DBA/class II B cluster; in one DCA haplotype, DCA*H5, the genes were tightly linked to the DBA/class II B clusters. Transcripts of DAA and DBA genes were found in O. niloticus hepatopancreas and spleen; transcripts of DCA genes were detected in the A. hansbaenschi cDNA library, but not in O. niloticus. These findings provide a basis for using class II haplotypes as markers in the study of adaptive radiation in the cichlid species flocks of the East African Great Lakes. PMID:10912508

  12. Selection and Trans-Species Polymorphism of Major Histocompatibility Complex Class II Genes in the Order Crocodylia

    PubMed Central

    Jaratlerdsiri, Weerachai; Isberg, Sally R.; Higgins, Damien P.; Miles, Lee G.; Gongora, Jaime

    2014-01-01

    Major Histocompatibility Complex (MHC) class II genes encode for molecules that aid in the presentation of antigens to helper T cells. MHC characterisation within and between major vertebrate taxa has shed light on the evolutionary mechanisms shaping the diversity within this genomic region, though little characterisation has been performed within the Order Crocodylia. Here we investigate the extent and effect of selective pressures and trans-species polymorphism on MHC class II α and β evolution among 20 extant species of Crocodylia. Selection detection analyses showed that diversifying selection influenced MHC class II β diversity, whilst diversity within MHC class II α is the result of strong purifying selection. Comparison of translated sequences between species revealed the presence of twelve trans-species polymorphisms, some of which appear to be specific to the genera Crocodylus and Caiman. Phylogenetic reconstruction clustered MHC class II α sequences into two major clades representing the families Crocodilidae and Alligatoridae. However, no further subdivision within these clades was evident and, based on the observation that most MHC class II α sequences shared the same trans-species polymorphisms, it is possible that they correspond to the same gene lineage across species. In contrast, phylogenetic analyses of MHC class II β sequences showed a mixture of subclades containing sequences from Crocodilidae and/or Alligatoridae, illustrating orthologous relationships among those genes. Interestingly, two of the subclades containing sequences from both Crocodilidae and Alligatoridae shared specific trans-species polymorphisms, suggesting that they may belong to ancient lineages pre-dating the divergence of these two families from the common ancestor 85–90 million years ago. The results presented herein provide an immunogenetic resource that may be used to further assess MHC diversity and functionality in Crocodylia. PMID:24503938

  13. General approach to the fractionation and class determination of complex mixtures of chlorinated aromatic compounds.

    PubMed

    Albro, P W; Parker, C E

    1980-09-19

    Among the "inadvertent" environmental pollutants are polychlorinated biphenyls, terphenyls, quadphenyls, naphthalenes, diphenyl ethers, dibenzofurans, dibenzo-p-dioxins and benzenes. Mixtures of these classes of compounds also occur in commercial products such as transformer fluids. To analyze such mixtures, gas chromatography--mass spectrometry may be combined with pre-fractionation on basic and acidic alumina columns and semi-quantitative perchlorination techniques. These procedures are illustrated for synthetic mixtures as well as for two samples of stored transformer fluid. Although the described procedure is mainly intended to be applied to the characterization of the major class components of such mixtures, it is also applicable to the determination of trace components such as the dibenzofurans in commercial polychlorinated biphenyls. The mass spectral techniques permit the simultaneous patterning, or "fingerprinting", of the compounds comprising each major class of chlorinated aromatics present. PMID:7451593

  14. Two-dimensional nuclear magnetic resonance analysis of a labeled peptide bound to a class II major histocompatibility complex molecule.

    PubMed

    Driscoll, P C; Altman, J D; Boniface, J J; Sakaguchi, K; Reay, P A; Omichinski, J G; Appella, E; Davis, M M

    1993-07-20

    The formation of peptide/major histocompatibility complex (MHC) complexes and their subsequent recognition by T cells is a pivotal event in the initiation of an immune response. While X-ray crystal structures are now available for class I MHC/peptide complexes, little detailed structural information is known about the class II MHC equivalent, and there are no solution structure data for either. A 16 amino acid residue moth cytochrome c peptide (residues 88 to 103) was 13C-labeled for two-dimensional isotope-edited NMR analysis. The peptide was labeled either selectively in the methyl groups of alanine residues or uniformly at every carbon position, and bound to unlabeled soluble mouse I-Ek class II MHC molecules. Although alpha-helical in the native cytochrome c protein and with no uniform structure in solution, the peptide is bound to the I-Ek molecule with the alpha-carbon atoms of the 11 C-terminal residues held in the binding groove. This indicates that the class II MHC peptide binding site is somewhat larger than that of class I MHC molecules (> or = 11 amino acid residues versus 8 to 10 amino acid residues), consistent with recent data on eluted peptides. Despite the large size of the complex (approximately 70 kDa), nuclear Overhauser effects are clearly detectable between peptide side-chains and the MHC molecule. Indications of the buried or exposed nature of particular side-chains within the bound peptide are derived from the NMR data and these are used together with information from previous biological studies to propose a crude model of the interaction of the peptide with the groove of the MHC molecule. We find no evidence for a conformational change in the peptide/MHC complex in the spectra at pH 5.0 versus pH 7.0, despite a 40-fold faster on-rate for the peptide at the lower pH value. PMID:8393933

  15. The intricate regulation and complex functions of the Class III phosphoinositide 3-kinase Vps34.

    PubMed

    Backer, Jonathan M

    2016-08-01

    The Class III phosphoinositide 3-kinase Vps34 (vacuolar protein sorting 34) plays important roles in endocytic trafficking, macroautophagy, phagocytosis, cytokinesis and nutrient sensing. Recent studies have provided exciting new insights into the structure and regulation of this lipid kinase, and new cellular functions for Vps34 have emerged. This review critically examines the wealth of new data on this important enzyme, and attempts to integrate these findings with current models of Vps34 signalling. PMID:27470591

  16. Characterization and 454 pyrosequencing of Major Histocompatibility Complex class I genes in the great tit reveal complexity in a passerine system

    PubMed Central

    2012-01-01

    Background The critical role of Major Histocompatibility Complex (Mhc) genes in disease resistance and their highly polymorphic nature make them exceptional candidates for studies investigating genetic effects on survival, mate choice and conservation. Species that harbor many Mhc loci and high allelic diversity are particularly intriguing as they are potentially under strong selection and studies of such species provide valuable information as to the mechanisms maintaining Mhc diversity. However comprehensive genotyping of complex multilocus systems has been a major challenge to date with the result that little is known about the consequences of this complexity in terms of fitness effects and disease resistance. Results In this study, we genotyped the Mhc class I exon 3 of the great tit (Parus major) from two nest-box breeding populations near Oxford, UK that have been monitored for decades. Characterization of Mhc class I exon 3 was adopted and bidirectional sequencing was carried using the 454 sequencing platform. Full analysis of sequences through a stepwise variant validation procedure allowed reliable typing of more than 800 great tits based on 214,357 reads; from duplicates we estimated the repeatability of typing as 0.94. A total of 862 alleles were detected, and the presence of at least 16 functional loci was shown - the highest number characterized in a wild bird species. Finally, the functional alleles were grouped into 17 supertypes based on their antigen binding affinities. Conclusions We found extreme complexity at the Mhc class I of the great tit both in terms of allelic diversity and gene number. The presence of many functional loci was shown, together with a pseudogene family and putatively non-functional alleles; there was clear evidence that functional alleles were under strong balancing selection. This study is the first step towards an in-depth analysis of this gene complex in this species, which will help understanding how parasite

  17. Mechanism for Amyloid Precursor-like Protein 2 Enhancement of Major Histocompatibility Complex Class I Molecule Degradation*

    PubMed Central

    Tuli, Amit; Sharma, Mahak; Capek, Haley L.; Naslavsky, Naava; Caplan, Steve; Solheim, Joyce C.

    2009-01-01

    Earlier studies have demonstrated interaction of the murine major histocompatibility complex (MHC) class I molecule Kd with amyloid precursor-like protein 2 (APLP2), a ubiquitously expressed member of the amyloid precursor protein family. Our current findings indicate that APLP2 is internalized in a clathrin-dependent manner, as shown by utilization of inhibitors of the clathrin pathway. Furthermore, we demonstrated that APLP2 and Kd bind at the cell surface and are internalized together. The APLP2 cytoplasmic tail contains two overlapping consensus motifs for binding to the adaptor protein-2 complex, and mutation of a tyrosine shared by both motifs severely impaired APLP2 internalization and ability to promote Kd endocytosis. Upon increased expression of wild type APLP2, Kd molecules were predominantly directed to the lysosomes rather than recycled to the plasma membrane. These findings suggest a model in which APLP2 binds Kd at the plasma membrane, facilitates uptake of Kd in a clathrin-dependent manner, and routes the endocytosed Kd to the lysosomal degradation pathway. Thus, APLP2 has a multistep trafficking function that influences the expression of major histocompatibility complex class I molecules at the plasma membrane. PMID:19808674

  18. Antitumor Activity of a Monoclonal Antibody Targeting Major Histocompatibility Complex Class I–Her2 Peptide Complexes

    PubMed Central

    2013-01-01

    Background Applications of trastuzumab are limited to breast cancer patients with high Her2-expressing tumors. We developed a T-cell receptor mimic (TCRm) monoclonal antibody (hereafter called RL1B) that targets the Her2-E75 peptide (residues 369–377)–HLA-A2 complex and examined its effects in Her2-expressing cancer cells. Methods RL1B binding affinity was determined by surface plasmon resonance and specificity was demonstrated using Her2 antigen-positive and negative tumor cell lines. Immunohistochemistry was used to assess binding to frozen sections of human carcinomas (n = 3). Antitumor activity mediated by RL1B and trastuzumab against Her2+ tumor cell lines was evaluated using the WST-1 cell viability assay and caspase-3 and poly(ADP-ribose) polymerase cleavage assays. A xenograft mouse model (n = 6 per group) was used to assess RL1B antitumor activity. Mechanisms of RL1B-mediated cytotoxicity were evaluated with confocal microscopy, flow cytometry, and histology. All statistical tests were two-sided. Results RL1B bound with high specificity and affinity to the E75 peptide–HLA-A2 complex in all Her2+ and HLA-A2+ cancer cell lines and human carcinomas. Compared with control antibody, RL1B suppressed growth of low Her2–expressing breast tumors in mice (mean volume, RL1B vs control = 241mm3 vs 1531mm3; P = .0109) and statistically significantly increased mouse survival (P = .0098). It reduced viability compared to control monoclonal antibody–treated cells and statistically significantly increased caspase 3 activation of all Her2+ carcinoma cell lines tested, whereas trastuzumab induced apoptosis only in high Her2–expressing cancer cells. Mechanisms of RL1B cytotoxicity were associated with antibody internalization and intracellular signaling. Conclusion The TCRm RL1B could be a new approach to immunotherapy of Her2-expressing malignancies. PMID:23300219

  19. Structure and Polymorphism of the Major Histocompatibility Complex Class II Region in the Japanese Crested Ibis, Nipponia nippon

    PubMed Central

    Taniguchi, Yukio; Matsumoto, Keisuke; Matsuda, Hirokazu; Yamada, Takahisa; Sugiyama, Toshie; Homma, Kosuke; Kaneko, Yoshinori; Yamagishi, Satoshi; Iwaisaki, Hiroaki

    2014-01-01

    The major histocompatibility complex (MHC) is a highly polymorphic genomic region that plays a central role in the immune system. Despite its functional consistency, the genomic structure of the MHC differs substantially among organisms. In birds, the MHC-B structures of Galliformes, including chickens, have been well characterized, but information about other avian MHCs remains sparse. The Japanese Crested Ibis (Nipponia nippon, Pelecaniformes) is an internationally conserved, critically threatened species. The current Japanese population of N. nippon originates from only five founders; thus, understanding the genetic diversity among these founders is critical for effective population management. Because of its high polymorphism and importance for disease resistance and other functions, the MHC has been an important focus in the conservation of endangered species. Here, we report the structure and polymorphism of the Japanese Crested Ibis MHC class II region. Screening of genomic libraries allowed the construction of three contigs representing different haplotypes of MHC class II regions. Characterization of genomic clones revealed that the MHC class II genomic structure of N. nippon was largely different from that of chicken. A pair of MHC-IIA and -IIB genes was arranged head-to-head between the COL11A2 and BRD2 genes. Gene order in N. nippon was more similar to that in humans than to that in chicken. The three haplotypes contained one to three copies of MHC-IIA/IIB gene pairs. Genotyping of the MHC class II region detected only three haplotypes among the five founders, suggesting that the genetic diversity of the current Japanese Crested Ibis population is extremely low. The structure of the MHC class II region presented here provides valuable insight for future studies on the evolution of the avian MHC and for conservation of the Japanese Crested Ibis. PMID:25247679

  20. Human-specific evolution of killer cell immunoglobulin-like receptor recognition of major histocompatibility complex class I molecules.

    PubMed

    Parham, Peter; Norman, Paul J; Abi-Rached, Laurent; Guethlein, Lisbeth A

    2012-03-19

    In placental mammals, natural killer (NK) cells are a population of lymphocytes that make unique contributions to immune defence and reproduction, functions essential for survival of individuals, populations and species. Modulating these functions are conserved and variable NK-cell receptors that recognize epitopes of major histocompatibility complex (MHC) class I molecules. In humans, for example, recognition of human leucocyte antigen (HLA)-E by the CD94:NKG2A receptor is conserved, whereas recognition of HLA-A, B and C by the killer cell immunoglobulin-like receptors (KIRs) is diversified. Competing demands of the immune and reproductive systems, and of T-cell and NK-cell immunity-combined with the segregation on different chromosomes of variable NK-cell receptors and their MHC class I ligands-drive an unusually rapid evolution that has resulted in unprecedented levels of species specificity, as first appreciated from comparison of mice and humans. Counterparts to human KIR are present only in simian primates. Observed in these species is the coevolution of KIR and the four MHC class I epitopes to which human KIR recognition is restricted. Unique to hominids is the emergence of the MHC-C locus as a supplier of specialized and superior ligands for KIR. This evolutionary trend is most highly elaborated in the chimpanzee. Unique to the human KIR locus are two groups of KIR haplotypes that are present in all human populations and subject to balancing selection. Group A KIR haplotypes resemble chimpanzee KIR haplotypes and are enriched for genes encoding KIR that bind HLA class I, whereas group B KIR haplotypes are enriched for genes encoding receptors with diminished capacity to bind HLA class I. Correlating with their balance in human populations, B haplotypes favour reproductive success, whereas A haplotypes favour successful immune defence. Evolution of the B KIR haplotypes is thus unique to the human species. PMID:22312047

  1. Charge-transfer complexes of sulfamethoxazole drug with different classes of acceptors

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Korashy, Sabry A.; El-Deen, Ibrahim M.; El-Sayed, Shaima M.

    2010-09-01

    The charge-transfer complexes of the donor sulfamethoxazole (SZ) with iodine (I 2), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), p-chloranil (CHL) and picric acid (PA) have been studied spectrophotometrically in chloroform or methanol at room temperature using absorption spectrophotometer. The results indicate that formation of CT-complexes in case of four acceptors. The stoichiometry of the complexes was found to be 1:1 ratio by molar ratio method between donor and acceptor with maximum absorption bands (CT band). The data are discussed in terms of formation constant ( KCT), molar extinction coefficient ( ɛCT), standard free energy (Δ G°), oscillator strength (ƒ), transition dipole moment ( μ), resonance energy ( RN) and ionization potential ( ID). The results indicate that the formation constant ( KCT) for the complexes were shown to be dependent upon the nature of electron acceptor, donor and polarity of solvents which were used. IR, 1H NMR, mass spectra, UV-Vis techniques, elemental analyses (CHN) and TG-DTG investigation were used to characterize the four sulfamethoxazole charge-transfer complexes.

  2. Insights into the activation mechanism of class I HDAC complexes by inositol phosphates

    PubMed Central

    Watson, Peter J.; Millard, Christopher J.; Riley, Andrew M.; Robertson, Naomi S.; Wright, Lyndsey C.; Godage, Himali Y.; Cowley, Shaun M.; Jamieson, Andrew G.; Potter, Barry V. L.; Schwabe, John W. R.

    2016-01-01

    Histone deacetylases (HDACs) 1, 2 and 3 form the catalytic subunit of several large transcriptional repression complexes. Unexpectedly, the enzymatic activity of HDACs in these complexes has been shown to be regulated by inositol phosphates, which bind in a pocket sandwiched between the HDAC and co-repressor proteins. However, the actual mechanism of activation remains poorly understood. Here we have elucidated the stereochemical requirements for binding and activation by inositol phosphates, demonstrating that activation requires three adjacent phosphate groups and that other positions on the inositol ring can tolerate bulky substituents. We also demonstrate that there is allosteric communication between the inositol-binding site and the active site. The crystal structure of the HDAC1:MTA1 complex bound to a novel peptide-based inhibitor and to inositol hexaphosphate suggests a molecular basis of substrate recognition, and an entropically driven allosteric mechanism of activation. PMID:27109927

  3. Major histocompatibility complex class II alleles and haplotypes associated with non-suppurative meningoencephalitis in greyhounds.

    PubMed

    Shiel, R E; Kennedy, L J; Nolan, C M; Mooney, C T; Callanan, J J

    2014-09-01

    Non-suppurative meningoencephalitis is a breed-restricted canine neuroinflammatory disorder affecting young greyhounds in Ireland. A genetic risk factor is suspected because of the development of disease in multiple siblings and an inability to identify a causative infectious agent. The aim of this study was to examine potential associations between dog leucocyte antigen (DLA) class II haplotype and the presence of the disease. DLA three locus haplotypes were determined in 31 dogs with non-suppurative meningoencephalitis and in 115 healthy control dogs using sequence-based typing (SBT) methods. All dogs were unrelated at the parental level. Two haplotypes (DRB1*01802/DQA1*00101/DQB1*00802 and DRB1*01501/DQA1*00601/DQB1*02201) were significantly (P = 0.0099 and 0.037) associated with the presence of meningoencephalitis, with odds ratios (95% confidence interval) of 5.531 (1.168-26.19) and 3.736 (1.446-9.652), respectively. These results confirm that there is an association between DLA class II haplotype and greyhound meningoencephalitis, suggesting an immunogenetic risk factor for the development of the disease. Greyhound meningoencephalitis may be a suitable model for human neuroinflammatory diseases with an immunogenetic component. PMID:24851745

  4. Restriction fragment length polymorphism within the class I gene loci of the equine major histocompatibility complex

    SciTech Connect

    Alexander, A.J.; Bailey, E.; Woodward, J.G.

    1986-03-05

    Fourteen standard bred horses were serotyped as homozygous for 1 of 6 Equine Leukocyte Antigen (ELA) specificities. DNA was purified from peripheral leukocytes and digested with Hind III or Pvu II. Southern blot hybridization analysis was carried out using a /sup 32/P-labeled mouse cDNA probe (PH2IIa) specific for class I MHC genes. Both enzymes generated blots that contained a large number of bands (23 to 30) per horse. Significant polymorphism existed among most fragment sizes, while a dozen highly conserved band sizes suggested the presence of Qa/tla - like genes. Only 2 animals (both W6's) showed identical band patterns. Polymorphism was greatest between horses of different serotypes and was significantly decreased within serotypes. Unique bands were present on both blots for both W1's and W6's and may account for the serologic specificity seen in ELA W1 and W6 horses. This study is consistent with the findings in other higher vertebrates and implies that the MHC of the horse includes a highly polymorphic class I multigene family.

  5. Dissociation of β2-microglobulin determines the surface quality control of major histocompatibility complex class I molecules.

    PubMed

    Montealegre, Sebastián; Venugopalan, Vaishnavi; Fritzsche, Susanne; Kulicke, Corinna; Hein, Zeynep; Springer, Sebastian

    2015-07-01

    Major histocompatibility complex class I proteins, which present antigenic peptides to cytotoxic T lymphocytes at the surface of all nucleated cells, are endocytosed and destroyed rapidly once their peptide ligand has dissociated. The molecular mechanism of this cellular quality control process, which prevents rebinding of exogenous peptides and thus erroneous immune responses, is unknown. To identify the nature of the decisive step in endocytic sorting of class I molecules and its location, we have followed the removal of optimally and suboptimally peptide-loaded murine H-2K(b) class I proteins from the cell surface. We find that the binding of their light chain, β2-microglobulin (β2m), protects them from endocytic destruction. Thus, the extended survival of suboptimally loaded K(b) molecules at 25°C is attributed to decreased dissociation of β2m. Because all forms of K(b) are constantly internalized but little β2m-receptive heavy chain is present at the cell surface, it is likely that β2m dissociation and recognition of the heavy chain for lysosomal degradation take place in an endocytic compartment. PMID:25782992

  6. Class II major histocompatibility complex antigen expression on peripheral blood monocytes in patients with inflammatory bowel disease.

    PubMed Central

    Gardiner, K R; Crockard, A D; Halliday, M I; Rowlands, B J

    1994-01-01

    Macrophage major histocompatibility complex (MHC) class II antigen expression is associated with defective antigen presentation to T lymphocytes in animals and is predictive of patient outcome after major trauma or sepsis. In this study, class II antigen (HLA-DR and DQ) expression on peripheral blood monocytes was investigated in patients with inflammatory bowel disease in relation to disease activity and outcome. The percentage positivity and fluorescent intensity of expression of HLA-DR and DQ antigens on monocytes were determined in whole blood samples using dual colour immunofluorescence labelling and flow cytometry. Disease activity was assessed using clinical and laboratory indices. There was no significant difference in percentage positivity or fluorescent intensity of class II antigen expression between patients with Crohn's disease, those with ulcerative colitis, and healthy volunteers. The percentage of monocytes displaying HLA-DR positivity was significantly decreased in patients with active ulcerative colitis (active %: 49.5 (5.6); inactive %: 78.9 (6.9); p = 0.01). Data expressed as mean (SEM). In patients requiring surgical resection of diseased bowel, the percentage of monocytes displaying HLA-DR positivity (51.9 (4.0) %) was significantly reduced compared with patients receiving medical treatment alone (81.1 (3.5) %; p < 0.001). Reduced monocyte HLA-DR expression is therefore associated with disease activity and seems to predict outcome in patients with inflammatory bowel disease. PMID:8174990

  7. Expression of bovine non-classical major histocompatibility complex class 1 proteins in mouse P815 and human K562 cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Major histocompatibility complex class I (MHC-I) proteins can be expressed as cell surface or secreted proteins. To investigate whether bovine non-classical MHC-I proteins are expressed as cell surface or secreted proteins, and to assess the reactivity pattern of monoclonal antibodies with non-class...

  8. Domain structures and molecular evolution of class I and class II major histocompatibility gene complex (MHC) products deduced from amino acid and nucleotide sequence homologies

    NASA Astrophysics Data System (ADS)

    Ohnishi, Koji

    1984-12-01

    Domain structures of class I and class II MHC products were analyzed from a viewpoint of amino acid and nucleotide sequence homologies. Alignment statistics revealed that class I (transplantation) antigen H chains consist of four mutually homologous domains, and that class II (HLA-DR) antigen β and α chains are both composed of three mutually homologous ones. The N-terminal three and two domains of class I and class II (both β and α) gene products, respectively, all of which being ˜90 residues long, were concluded to be homologous to β2-microglobulin (β2M). The membraneembedded C-terminal shorter domains of these MHC products were also found to be homologous to one another and to the third domain of class I H chains. Class I H chains were found to be more closely related to class II α chains than to class II β chains. Based on these findings, an exon duplication history from a common ancestral gene encoding a β2M-like primodial protein of one-domain-length up to the contemporary MHC products was proposed.

  9. Class II malocclusion with complex problems treated with a novel combination of lingual orthodontic appliances and lingual arches.

    PubMed

    Yanagita, Takeshi; Nakamura, Masahiro; Kawanabe, Noriaki; Yamashiro, Takashi

    2014-07-01

    This case report describes a novel method of combining lingual appliances and lingual arches to control horizontal problems. The patient, who was 25 years of age at her first visit to our hospital with a chief complaint of crooked anterior teeth, was diagnosed with skeletal Class II and Angle Class II malocclusion with anterior deep bite, lateral open bite, premolar crossbite, and severe crowding in both arches. She was treated with premolar extractions and temporary anchorage devices. Conventionally, it is ideal to use labial brackets simultaneously with appliances, such as a lingual arch, a quad-helix, or a rapid expansion appliance, in patients with complex problems requiring horizontal, anteroposterior, and vertical control; however, this patient strongly requested orthodontic treatment with lingual appliances. A limitation of lingual appliances is that they cannot be used with other conventional appliances. In this report, we present the successful orthodontic treatment of a complex problem using modified lingual appliances that enabled combined use of a conventional lingual arch. PMID:24975004

  10. Staphylococcus-mediated T-cell activation and spontaneous natural killer cell activity in the absence of major histocompatibility complex class II molecules

    NASA Technical Reports Server (NTRS)

    Chapes, S. K.; Hoynowski, S. M.; Woods, K. M.; Armstrong, J. W.; Beharka, A. A.; Iandolo, J. J.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    We used major histocompatibility complex class II antigen-deficient transgenic mice to show that in vitro natural killer cell cytotoxicity and T-cell activation by staphylococcal exotoxins (superantigens) are not dependent upon the presence of major histocompatibility complex class II molecules. T cells can be activated by exotoxins in the presence of exogenously added interleukin 1 or 2 or in the presence of specific antibody without exogenously added cytokines.

  11. Pan-Specific Prediction of Peptide-MHC Class I Complex Stability, a Correlate of T Cell Immunogenicity.

    PubMed

    Rasmussen, Michael; Fenoy, Emilio; Harndahl, Mikkel; Kristensen, Anne Bregnballe; Nielsen, Ida Kallehauge; Nielsen, Morten; Buus, Søren

    2016-08-15

    Binding of peptides to MHC class I (MHC-I) molecules is the most selective event in the processing and presentation of Ags to CTL, and insights into the mechanisms that govern peptide-MHC-I binding should facilitate our understanding of CTL biology. Peptide-MHC-I interactions have traditionally been quantified by the strength of the interaction, that is, the binding affinity, yet it has been shown that the stability of the peptide-MHC-I complex is a better correlate of immunogenicity compared with binding affinity. In this study, we have experimentally analyzed peptide-MHC-I complex stability of a large panel of human MHC-I allotypes and generated a body of data sufficient to develop a neural network-based pan-specific predictor of peptide-MHC-I complex stability. Integrating the neural network predictors of peptide-MHC-I complex stability with state-of-the-art predictors of peptide-MHC-I binding is shown to significantly improve the prediction of CTL epitopes. The method is publicly available at http://www.cbs.dtu.dk/services/NetMHCstabpan. PMID:27402703

  12. Analysis and formulation of a class of complex dynamic optimization problems

    NASA Astrophysics Data System (ADS)

    Kameswaran, Shivakumar

    The Direct Transcription approach, also known as the direct simultaneous approach, is a widely used solution strategy for the solution of dynamic optimization problems involving differential-algebraic equations (DAEs). Direct transcription refers to the procedure of approximating the infinite dimensional problem by a finite dimensional one, which is then solved using a nonlinear programming (NLP) solver tailored to large-scale problems. Systems governed by partial differential equations (PDEs) can also be handled by spatially discretizing the PDEs to convert them to a system of DAEs. The objective of this thesis is firstly to ensure that direct transcription using Radau collocation is provably correct, and secondly to widen the applicability of the direct simultaneous approach to a larger class of dynamic optimization and optimal control problems (OCPs). This thesis aims at addressing these issues using rigorous theoretical tools and/or characteristic examples, and at the same time use the results for solving large-scale industrial applications to realize the benefits. The first part of this work deals with the analysis of convergence rates for direct transcription of unconstrained and final-time equality constrained optimal control problems. The problems are discretized using collocation at Radau points. Convergence is analyzed from an NLP/matrix-algebra perspective, which enables the prediction of the conditioning of the direct transcription NLP as the mesh size becomes finer. Several convergence results are presented along with tests on numerous example problems. These convergence results lead to an adjoint estimation procedure given the Lagrange multipliers for the large-scale NLP. The work also reveals the role of process control concepts such as controllability on the convergence analysis, and provides a very important link between control and optimization inside the framework of dynamic optimization. As an effort to extend the applicability of the direct

  13. UVRAG is required for virus entry through combinatorial interaction with the class C-Vps complex and SNAREs

    PubMed Central

    Pirooz, Sara Dolatshahi; He, Shanshan; Zhang, Tian; Zhang, Xiaowei; Zhao, Zhen; Oh, Soohwan; O’Connell, Douglas; Khalilzadeh, Payam; Amini-Bavil-Olyaee, Samad; Farzan, Michael; Liang, Chengyu

    2014-01-01

    Enveloped viruses exploit the endomembrane system to enter host cells. Through a cascade of membrane-trafficking events, virus-bearing vesicles fuse with acidic endosomes and/or lysosomes mediated by SNAREs triggering viral fusion. However, the molecular mechanisms underlying this process remain elusive. Here, we found that UV-radiation resistance-associated gene (UVRAG), an autophagic tumor suppressor, is required for the entry of the prototypic negative-strand RNA virus, including influenza A virus and vesicular stomatitis virus, by a mechanism independent of IFN and autophagy. UVRAG mediates viral endocytic transport and membrane penetration through interactions with the class C vacuolar protein sorting (C-Vps) tethering complex and endosomal glutamine-containing SNAREs [syntaxin 7 (STX7), STX8, and vesicle transport through t-SNARE homolog 1B (Vti1b)], leading to the assembly of a fusogenic trans-SNARE complex involving vesicle-associated membrane protein (VAMP8), but not VAMP7. Indeed, UVRAG stimulates VAMP8 translocation to virus-bearing endosomes. Inhibition of VAMP8, but not VAMP7, significantly reduces viral entry. Our data indicate that UVRAG, in concert with C-Vps, regulates viral entry by assembling a specific fusogenic SNARE complex. Thus, UVRAG governs downstream viral entry, highlighting an important pathway capable of potential antiviral therapeutics. PMID:24550300

  14. The great diversity of major histocompatibility complex class II genes in Philippine native cattle.

    PubMed

    Takeshima, S N; Miyasaka, T; Polat, M; Kikuya, M; Matsumoto, Y; Mingala, C N; Villanueva, M A; Salces, A J; Onuma, M; Aida, Y

    2014-12-01

    Bovine leukocyte antigens (BoLA) are extensively used as markers for bovine disease and immunological traits. However, none of the BoLA genes in Southeast Asian breeds have been characterized by polymerase chain reaction (PCR)-sequence-based typing (SBT). Therefore, we sequenced exon 2 of the BoLA class II DRB3 gene from 1120 individual cows belonging to the Holstein, Sahiwal, Simbrah, Jersey, Brahman, and Philippine native breeds using PCR-SBT. Several cross-breeds were also examined. BoLA-DRB3 PCR-SBT identified 78 previously reported alleles and five novel alleles. The number of BoLA-DRB3 alleles identified in each breed from the Philippines was higher (71 in Philippine native cattle, 58 in Brahman, 46 in Holstein × Sahiwal, and 57 in Philippine native × Brahman) than that identified in breeds from other countries (e.g., 23 alleles in Japanese Black and 35 in Bolivian Yacumeño cattle). A phylogenetic tree based on the DA distance calculated from the BoLA-DRB3 allele frequency showed that Philippine native cattle from different Philippine islands are closely related, and all of them are closely similar to Philippine Brahman cattle but not to native Japanese and Latin American breeds. Furthermore, the BoLA-DRB3 allele frequency in Philippine native cattle from Luzon Island, located in the Northern Philippines was different from that in cattle from Iloilo, Bohol, and Leyte Islands, which are located in the Southern Philippines. Therefore, we conclude that Philippine native cattle can be divided into two populations, North and South areas. Moreover, a neutrality test revealed that Philippine native cattle from Leyte showed significantly greater genetic diversity, which may be maintained by balancing selection. This study shows that Asian breeds have high levels of BoLA-DRB3 polymorphism. This finding, especially the identification of five novel BoLA-DRB3 alleles, will be helpful for future SBT studies of BoLA-DRB3 alleles in East Asian cattle. PMID:25606401

  15. The great diversity of major histocompatibility complex class II genes in Philippine native cattle

    PubMed Central

    Takeshima, S.N.; Miyasaka, T.; Polat, M.; Kikuya, M.; Matsumoto, Y.; Mingala, C.N.; Villanueva, M.A.; Salces, A.J.; Onuma, M.; Aida, Y.

    2014-01-01

    Bovine leukocyte antigens (BoLA) are extensively used as markers for bovine disease and immunological traits. However, none of the BoLA genes in Southeast Asian breeds have been characterized by polymerase chain reaction (PCR)-sequence-based typing (SBT). Therefore, we sequenced exon 2 of the BoLA class II DRB3 gene from 1120 individual cows belonging to the Holstein, Sahiwal, Simbrah, Jersey, Brahman, and Philippine native breeds using PCR-SBT. Several cross-breeds were also examined. BoLA-DRB3 PCR-SBT identified 78 previously reported alleles and five novel alleles. The number of BoLA-DRB3 alleles identified in each breed from the Philippines was higher (71 in Philippine native cattle, 58 in Brahman, 46 in Holstein × Sahiwal, and 57 in Philippine native × Brahman) than that identified in breeds from other countries (e.g., 23 alleles in Japanese Black and 35 in Bolivian Yacumeño cattle). A phylogenetic tree based on the DA distance calculated from the BoLA-DRB3 allele frequency showed that Philippine native cattle from different Philippine islands are closely related, and all of them are closely similar to Philippine Brahman cattle but not to native Japanese and Latin American breeds. Furthermore, the BoLA-DRB3 allele frequency in Philippine native cattle from Luzon Island, located in the Northern Philippines was different from that in cattle from Iloilo, Bohol, and Leyte Islands, which are located in the Southern Philippines. Therefore, we conclude that Philippine native cattle can be divided into two populations, North and South areas. Moreover, a neutrality test revealed that Philippine native cattle from Leyte showed significantly greater genetic diversity, which may be maintained by balancing selection. This study shows that Asian breeds have high levels of BoLA-DRB3 polymorphism. This finding, especially the identification of five novel BoLA-DRB3 alleles, will be helpful for future SBT studies of BoLA-DRB3 alleles in East Asian cattle. PMID:25606401

  16. Evidence for a Complex Class of Nonadenylated mRNA in Drosophila

    PubMed Central

    Zimmerman, J. Lynn; Fouts, David L.; Manning, Jerry E.

    1980-01-01

    The amount, by mass, of poly(A+) mRNA present in the polyribosomes of third-instar larvae of Drosophila melanogaster, and the relative contribution of the poly(A+) mRNA to the sequence complexity of total polysomal RNA, has been determined. Selective removal of poly(A+) mRNA from total polysomal RNA by use of either oligo-dT-cellulose, or poly(U)-sepharose affinity chromatography, revealed that only 0.15% of the mass of the polysomal RNA was present as poly(A+) mRNA. The present study shows that this RNA hybridized at saturation with 3.3% of the single-copy DNA in the Drosophila genome. After correction for asymmetric transcription and reactability of the DNA, 7.4% of the single-copy DNA in the Drosophila genome is represented in larval poly(A+) mRNA. This corresponds to 6.73 x 106 nucleotides of mRNA coding sequences, or approximately 5,384 diverse RNA sequences of average size 1,250 nucleotides. However, total polysomal RNA hybridizes at saturation to 10.9% of the single-copy DNA sequences. After correcting this value for asymmetric transcription and tracer DNA reactability, 24% of the single-copy DNA in Drosophila is represented in total polysomal RNA. This corresponds to 2.18 x 107 nucleotides of RNA coding sequences or 17,440 diverse RNA molecules of size 1,250 nucleotides. This value is 3.2 times greater than that observed for poly(A+) mRNA, and indicates that ≃69% of the polysomal RNA sequence complexity is contributed by nonadenylated RNA. Furthermore, if the number of different structural genes represented in total polysomal RNA is ≃1.7 x 104, then the number of genes expressed in third-instar larvae exceeds the number of chromomeres in Drosophila by about a factor of three. This numerology indicates that the number of chromomeres observed in polytene chromosomes does not reflect the number of structural gene sequences in the Drosophila genome. PMID:6777246

  17. Expression of major histocompatibility complex class I and class II antigens in human Schwann cell cultures and effects of infection with Mycobacterium leprae.

    PubMed

    Samuel, N M; Mirsky, R; Grange, J M; Jessen, K R

    1987-06-01

    Recent experiments on rats have raised the possibility that Schwann cells can present antigens to T lymphocytes. We have investigated whether this mechanism might be relevant in leprosy by determining under what conditions human Schwann cells express class I and class II antigens, and whether infection with Mycobacterium leprae affects this expression. The distribution of these antigens was examined on human Schwann cells in dissociated cell cultures derived from human fetal peripheral nerves. We find that both Schwann cells and fibroblastic cells in these cultures normally express class I antigens but not class II antigens. When Schwann cells are infected with live Mycobacterium leprae for 48 h, 73% of Schwann cells phagocytose the bacteria. Mycobacterium leprae prevents 3H-thymidine incorporation into cultured human Schwann cells, but does not affect class I expression in these cells. Treatment of normal and Mycobacterium leprae infected cultures with gamma-interferon for 72 h induces class II expression on most Schwann cells but not on the majority of fibroblastic cells. The fact that human Schwann cells infected with Mycobacterium leprae can be induced by gamma-interferon to express class II antigens suggests that they may be able to present Mycobacterium leprae antigens to T lymphocytes and thus initiate immune responses against the bacteria. We suggest that a failure of this response, such as that seen within nerve trunks in lepromatous leprosy, is caused by deficient class II expression on Schwann cells. This deficiency in class II expression, in turn, may be caused by the reduced gamma-interferon production characteristic of lepromatous leprosy. PMID:3115648

  18. Selection, trans-species polymorphism, and locus identification of major histocompatibility complex class IIβ alleles of New World ranid frogs

    USGS Publications Warehouse

    Kiemnec-Tyburczy, Karen M.; Richmond, Jonathan Q.; Savage, Anna E.; Zamudio, Kelly R.

    2010-01-01

    Genes encoded by the major histocompatibility complex (MHC) play key roles in the vertebrate immune system. However, our understanding of the evolutionary processes and underlying genetic mechanisms shaping these genes is limited in many taxa, including amphibians, a group currently impacted by emerging infectious diseases. To further elucidate the evolution of the MHC in frogs (anurans) and develop tools for population genetics, we surveyed allelic diversity of the MHC class II ??1 domain in both genomic and complementary DNA of seven New World species in the genus Rana (Lithobates). To assign locus affiliation to our alleles, we used a "gene walking" technique to obtain intron 2 sequences that flanked MHC class II?? exon 2. Two distinct intron sequences were recovered, suggesting the presence of at least two class II?? loci in Rana. We designed a primer pair that successfully amplified an orthologous locus from all seven Rana species. In total, we recovered 13 alleles and documented trans-species polymorphism for four of the alleles. We also found quantitative evidence of selection acting on amino acid residues that are putatively involved in peptide binding and structural stability of the ??1 domain of anurans. Our results indicated that primer mismatch can result in polymerase chain reaction (PCR) bias, which influences the number of alleles that are recovered. Using a single locus may minimize PCR bias caused by primer mismatch, and the gene walking technique was an effective approach for generating single-copy orthologous markers necessary for future studies of MHC allelic variation in natural amphibian populations. ?? 2010 Springer-Verlag.

  19. Unusual evolutionary conservation and frequent DNA segment exchange in class I genes of the major histocompatibility complex.

    PubMed Central

    Hayashida, H; Miyata, T

    1983-01-01

    From comparisons of homologous DNA sequences for many different genes, it was shown that the silent positions of protein-encoding regions and introns evolve at high and remarkably similar rates for different genes. In addition, both silent positions and introns behave like clocks; they accumulated base substitutions at approximately constant rates with respect to geological time. The rates of evolution were estimated to be 5.5 X 10(-9), 3.7 X 10(-9), and 5.3 X 10(-9) per site per year for silent positions, short introns (less than approximately equal to 300 base pairs), and long introns (more than approximately equal to 500 base pairs), respectively. Contrary to expectation from the evolutionary clocks, DNA sequence comparison between pHLA 12.4 (a cloned HLA sequence) of man and Ld together with other H-2 genes of mouse, the class I genes of the major histocompatibility complex, revealed a surprisingly small amount of base substitution for both the introns and the silent positions; the degree of divergence is only about 60% of that of standard genes in the same species comparison. Furthermore, several segmental homologies have been observed between the class I genes of mouse, suggesting the frequent occurrence of gene conversion or double unequal crossing-over in evolution. Interrelations between the extreme polymorphism of the class I genes, the low evolutionary drift of the introns and the silent positions, and the frequent gene conversion or unequal crossing-over within the mouse genes are discussed. PMID:6573677

  20. Association of hypothyroid disease in Doberman Pinscher dogs with a rare major histocompatibility complex DLA class II haplotype.

    PubMed

    Kennedy, L J; Huson, H J; Leonard, J; Angles, J M; Fox, L E; Wojciechowski, J W; Yuncker, C; Happ, G M

    2006-01-01

    Canine hypothyroid disease is similar to Hashimoto's disease in humans, which has been shown to be associated with human major histocompatibility complex (MHC) genes. We have collected 27 Doberman Pinschers affected with primary hypothyroid disease and compared their MHC class II haplotypes with 129 unaffected Doberman Pinschers. Three dog-leucocyte antigen (DLA) genes, DLA-DRB1, DQA1 and DQB1, were characterized by sequence-based typing and assigned to haplotypes for each dog. One rare haplotype was found at an increased frequency in the affected dogs compared to the unaffected dogs (Odds ratio = 2.43, P < 0.02). This haplotype has only been found in Doberman Pinschers and Labradors to date. PMID:16451201

  1. New horizons in mouse immunoinformatics: reliable in silico prediction of mouse class I histocompatibility major complex peptide binding affinity.

    PubMed

    Hattotuwagama, Channa K; Guan, Pingping; Doytchinova, Irini A; Flower, Darren R

    2004-11-21

    Quantitative structure-activity relationship (QSAR) analysis is a main cornerstone of modern informatic disciplines. Predictive computational models, based on QSAR technology, of peptide-major histocompatibility complex (MHC) binding affinity have now become a vital component of modern day computational immunovaccinology. Historically, such approaches have been built around semi-qualitative, classification methods, but these are now giving way to quantitative regression methods. The additive method, an established immunoinformatics technique for the quantitative prediction of peptide-protein affinity, was used here to identify the sequence dependence of peptide binding specificity for three mouse class I MHC alleles: H2-D(b), H2-K(b) and H2-K(k). As we show, in terms of reliability the resulting models represent a significant advance on existing methods. They can be used for the accurate prediction of T-cell epitopes and are freely available online ( http://www.jenner.ac.uk/MHCPred). PMID:15534705

  2. Proteasome Subtypes and Regulators in the Processing of Antigenic Peptides Presented by Class I Molecules of the Major Histocompatibility Complex

    PubMed Central

    Vigneron, Nathalie; Van den Eynde, Benoît J.

    2014-01-01

    The proteasome is responsible for the breakdown of cellular proteins. Proteins targeted for degradation are allowed inside the proteasome particle, where they are cleaved into small peptides and released in the cytosol to be degraded into amino acids. In vertebrates, some of these peptides escape degradation in the cytosol, are loaded onto class I molecules of the major histocompatibility complex (MHC) and displayed at the cell surface for scrutiny by the immune system. The proteasome therefore plays a key role for the immune system: it provides a continued sampling of intracellular proteins, so that CD8-positive T-lymphocytes can kill cells expressing viral or tumoral proteins. Consequently, the repertoire of peptides displayed by MHC class I molecules at the cell surface depends on proteasome activity, which may vary according to the presence of proteasome subtypes and regulators. Besides standard proteasomes, cells may contain immunoproteasomes, intermediate proteasomes and thymoproteasomes. Cells may also contain regulators of proteasome activity, such as the 19S, PA28 and PA200 regulators. Here, we review the effects of these proteasome subtypes and regulators on the production of antigenic peptides. We also discuss an unexpected function of the proteasome discovered through the study of antigenic peptides: its ability to splice peptides. PMID:25412285

  3. Pathogenicity of Bovine Neonatal Pancytopenia-associated vaccine-induced alloantibodies correlates with Major Histocompatibility Complex class I expression

    PubMed Central

    Benedictus, Lindert; Luteijn, Rutger D.; Otten, Henny; Jan Lebbink, Robert; van Kooten, Peter J. S.; Wiertz, Emmanuel J. H. J.; Rutten, Victor P. M. G.; Koets, Ad P.

    2015-01-01

    Bovine Neonatal Pancytopenia (BNP), a fatal bleeding syndrome of neonatal calves, is caused by maternal alloantibodies absorbed from colostrum and is characterized by lymphocytopenia, thrombocytopenia and bone marrow hypoplasia. An inactivated viral vaccine is the likely source of alloantigens inducing BNP-associated alloantibodies in the dam. In this study the specificity of BNP alloantibodies was assessed and was linked to the pathology of BNP. We demonstrated that Major Histocompatibility Complex class I (MHC I) and Very Late Antigen-3, an integrin α3/β1 heterodimer, were the major targets of BNP alloantibodies. However, alloantibody binding to various bovine cell types correlated with MHC I expression, rather than integrin β1 or α3 expression. Likewise, alloantibody-dependent complement-mediated cell lysis correlated strongly with MHC I expression. Examination of several tissues of third trimester bovine foetuses revealed that cells, shown to be affected in calves with BNP, were characterized by high MHC class I expression and high levels of alloantibody binding. We conclude that in spite of the heterogeneous specificity of BNP associated maternal alloantibodies, MHC I-specific antibodies mediate the pathogenicity of BNP in the calf and that cells with high MHC I expression were preferentially affected in BNP. PMID:26235972

  4. Amino Acid Polymorphisms in Hepatitis C Virus Core Affect Infectious Virus Production and Major Histocompatibility Complex Class I Molecule Expression.

    PubMed

    Tasaka-Fujita, Megumi; Sugiyama, Nao; Kang, Wonseok; Masaki, Takahiro; Masaski, Takahiro; Murayama, Asako; Yamada, Norie; Sugiyama, Ryuichi; Tsukuda, Senko; Watashi, Koichi; Asahina, Yasuhiro; Sakamoto, Naoya; Wakita, Takaji; Shin, Eui-Cheol; Kato, Takanobu

    2015-01-01

    Amino acid (aa) polymorphisms in the hepatitis C virus (HCV) genotype 1b core protein have been reported to be a potent predictor for poor response to interferon (IFN)-based therapy and a risk factor for hepatocarcinogenesis. We investigated the effects of these polymorphisms with genotype 1b/2a chimeric viruses that contained polymorphisms of Arg/Gln at aa 70 and Leu/Met at aa 91. We found that infectious virus production was reduced in cells transfected with chimeric virus RNA that had Gln at aa 70 (aa70Q) compared with RNA with Arg at aa 70 (aa70R). Using flow cytometry analysis, we confirmed that HCV core protein accumulated in aa70Q clone transfected cells, and it caused a reduction in cell-surface expression of major histocompatibility complex (MHC) class I molecules induced by IFN treatment through enhanced protein kinase R phosphorylation. We could not detect any effects due to the polymorphism at aa 91. In conclusion, the polymorphism at aa 70 was associated with efficiency of infectious virus production, and this deteriorated virus production in strains with aa70Q resulted in the intracellular accumulation of HCV proteins and attenuation of MHC class I molecule expression. These observations may explain the strain-associated resistance to IFN-based therapy and hepatocarcinogenesis of HCV. PMID:26365522

  5. Presentation of antagonist peptides to naive CD4+ T cells abrogates spatial reorganization of class II MHC peptide complexes on the surface of dendritic cells

    PubMed Central

    Chmielowski, Bartosz; Pacholczyk, Rafal; Kraj, Piotr; Kisielow, Pawel; Ignatowicz, Leszek

    2002-01-01

    By using dendritic cells (DCs) transduced with retroviruses encoding covalent Abβ/peptide fusion proteins tagged with fluorescent proteins, we followed the relocation of class II MHC molecules loaded with agonist or null peptides during the onset of activation of naive and effector CD4+ T cells. Clusters of T cell receptor (TCR)/CD3 complex formed in parallel with clusters of agonist class II MHC/peptide complexes on the surface of DCs. However, activation of naive but not effector T cells was accompanied by expulsion of the null class II MHC/peptide complexes from the T cell–DC interface. These effects were perturbed in the presence of exogenously supplied antagonist peptide. These results suggest that interference with selective relocation of agonist and null MHC/peptide complexes in the immunological synapse contributes to the inhibitory effect of antagonist peptides on the response of naive CD4+ T cells to agonist ligands. PMID:12411579

  6. Adaptor protein complexes AP-1 and AP-3 are required by the HHV-7 Immunoevasin U21 for rerouting of class I MHC molecules to the lysosomal compartment.

    PubMed

    Kimpler, Lisa A; Glosson, Nicole L; Downs, Deanna; Gonyo, Patrick; May, Nathan A; Hudson, Amy W

    2014-01-01

    The human herpesvirus-7 (HHV-7) U21 gene product binds to class I major histocompatibility complex (MHC) molecules and reroutes them to a lysosomal compartment. Trafficking of integral membrane proteins to lysosomes is mediated through cytoplasmic sorting signals that recruit heterotetrameric clathrin adaptor protein (AP) complexes, which in turn mediate protein sorting in post-Golgi vesicular transport. Since U21 can mediate rerouting of class I molecules to lysosomes even when lacking its cytoplasmic tail, we hypothesize the existence of a cellular protein that contains the lysosomal sorting information required to escort class I molecules to the lysosomal compartment. If such a protein exists, we expect that it might recruit clathrin adaptor protein complexes as a means of lysosomal sorting. Here we describe experiments demonstrating that the μ adaptins from AP-1 and AP-3 are involved in U21-mediated trafficking of class I molecules to lysosomes. These experiments support the idea that a cellular protein(s) is necessary for U21-mediated lysosomal sorting of class I molecules. We also examine the impact of transient versus chronic knockdown of these adaptor protein complexes, and show that the few remaining μ subunits in the cells are eventually able to reroute class I molecules to lysosomes. PMID:24901711

  7. Potent T Cell Activation with Dimeric Peptide–Major Histocompatibility Complex Class II Ligand: The Role of CD4 Coreceptor

    PubMed Central

    Hamad, Abdel Rahim A.; O'Herrin, Sean M.; Lebowitz, Michael S.; Srikrishnan, Ananth; Bieler, Joan; Schneck, Jonathan; Pardoll, Drew

    1998-01-01

    The interaction of the T cell receptor (TCR) with its cognate peptide–major histocompatibility complex (MHC) on the surface of antigen presenting cells (APCs) is a primary event during T cell activation. Here we used a dimeric IEk-MCC molecule to study its capacity to activate antigen-specific T cells and to directly analyze the role of CD4 in physically stabilizing the TCR–MHC interaction. Dimeric IEk-MCC stably binds to specific T cells. In addition, immobilized dimeric IEk-MCC can induce TCR downregulation and activate antigen-specific T cells more efficiently than anti-CD3. The potency of the dimeric IEk-MCC is significantly enhanced in the presence of CD4. However, CD4 does not play any significant role in stabilizing peptide-MHC–TCR interactions as it fails to enhance binding of IEk-MCC to specific T cells or influence peptide-MHC–TCR dissociation rate or TCR downregulation. Moreover, these results indicate that dimerization of peptide-MHC class II using an IgG molecular scaffold significantly increases its binding avidity leading to an enhancement of its stimulatory capacity while maintaining the physiological properties of cognate peptide–MHC complex. These peptide-MHC–IgG chimeras may, therefore, provide a novel approach to modulate antigen-specific T cell responses both in vitro and in vivo. PMID:9802975

  8. Molecular Architecture of the Major Histocompatibility Complex Class I-Binding Site of Ly49 Natural Killer Cell Receptors

    SciTech Connect

    Deng,L.; Cho, S.; Malchiodi, E.; Kerzic, M.; Dam, J.; Mariuzza, R.

    2008-01-01

    Natural killer (NK) cells play a vital role in the detection and destruction of virally infected and tumor cells during innate immune responses. The highly polymorphic Ly49 family of NK receptors regulates NK cell function by sensing major histocompatibility complex class I (MHC-I) molecules on target cells. Despite the determination of two Ly49-MHC-I complex structures, the molecular features of Ly49 receptors that confer specificity for particular MHC-I alleles have not been identified. To understand the functional architecture of Ly49-binding sites, we determined the crystal structures of Ly49C and Ly49G and completed refinement of the Ly49C-H-2Kb complex. This information, combined with mutational analysis of Ly49A, permitted a structure-based classification of Ly49s that we used to dissect the binding site into three distinct regions, each having different roles in MHC recognition. One region, located at the center of the binding site, has a similar structure across the Ly49 family and mediates conserved interactions with MHC-I that contribute most to binding. However, the preference of individual Ly49s for particular MHC-I molecules is governed by two regions that flank the central region and are structurally more variable. One of the flanking regions divides Ly49s into those that recognize both H-2D and H-2K versus only H-2D ligands, whereas the other discriminates among H-2D or H-2K alleles. The modular design of Ly49-binding sites provides a framework for predicting the MHC-binding specificity of Ly49s that have not been characterized experimentally.

  9. Schwann cell differentiation inhibits interferon-gamma induction of expression of major histocompatibility complex class II and intercellular adhesion molecule-1.

    PubMed

    Lisak, Robert P; Bealmear, Beverly; Benjamins, Joyce A

    2016-06-15

    Interferon-gamma (IFN-γ) upregulates major histocompatibility complex class II (MHC class II) antigens and intercellular adhesion molecule-1 (ICAM-1) on Schwann cells (SC) in vitro, but in nerves of animals and patients MHC class II is primarily expressed on inflammatory cells. We investigated whether SC maturation influences their expression. IFN-γ induced MHC class II and upregulated ICAM-1; the axolemma-like signal 8-bromo cyclic adenosine monophosphate (8 Br cAMP) with IFN-γ inhibited expression. Delaying addition of 8 Br cAMP to SC already exposed to IFN-γ inhibited ongoing expression; addition of IFN-γ to SC already exposed to 8 Br cAMP resulted in minimal expression. Variability of cytokine-induced MHC class II and ICAM-1 expression by SC in vivo may represent the variability of signals from axolemma. PMID:27235355

  10. Expression, refolding and crystallization of murine MHC class I H-2D{sup b} in complex with human β{sub 2}-microglobulin

    SciTech Connect

    Sandalova, Tatyana; Michaëlsson, Jakob; Harris, Robert A.; Ljunggren, Hans-Gustaf; Kärre, Klas; Schneider, Gunter; Achour, Adnane

    2005-12-01

    Mouse MHC class I H-2Db in complex with human β2m and the LCMV-derived peptide gp33 has been produced and crystallized. Resolution of the structure of this complex combined with the structural comparison with the previously solved crystal structure of H-2Db/mβ2m/gp33 should lead to a better understanding of how the β2m subunit affects the overall conformation of MHC complexes as well as the stability of the presented peptides. β{sub 2}-Microglobulin (β{sub 2}m) is non-covalently linked to the major histocompatibility (MHC) class I heavy chain and interacts with CD8 and Ly49 receptors. Murine MHC class I can bind human β{sub 2}m (hβ{sub 2}m) and such hybrid molecules are often used in structural and functional studies. The replacement of mouse β{sub 2}m (mβ{sub 2}m) by hβ{sub 2}m has important functional consequences for MHC class I complex stability and specificity, but the structural basis for this is unknown. To investigate the impact of species-specific β{sub 2}m subunits on MHC class I conformation, murine MHC class I H-2D{sup b} in complex with hβ{sub 2}m and the peptide gp33 derived from lymphocytic choriomeningitis virus (LCMV) has been expressed, refolded in vitro and crystallized. Crystals containing two complexes per asymmetric unit and belonging to the space group P2{sub 1}, with unit-cell parameters a = 68.1, b = 65.2, c = 101.9 Å, β = 102.4°, were obtained.

  11. Crystal structures of the class D beta-lactamase OXA-13 in the native form and in complex with meropenem.

    PubMed

    Pernot, L; Frénois, F; Rybkine, T; L'Hermite, G; Petrella, S; Delettré, J; Jarlier, V; Collatz, E; Sougakoff, W

    2001-07-20

    The therapeutic problems posed by class D beta-lactamases, a family of serine enzymes that hydrolyse beta-lactam antibiotics following an acylation-deacylation mechanism, are increased by the very low level of sensitivity of these enzymes to beta-lactamase inhibitors. To gain structural and mechanistic insights to aid the design of new inhibitors, we have determined the crystal structure of OXA-13 from Pseudomonas aeruginosa in the apo form and in complex with the carbapenem meropenem. The native form consisted of a dimer displaying an overall organisation similar to that found in the closely related enzyme OXA-10. In the acyl-enzyme complex, the positioning of the antibiotic appeared to be ensured mainly by (i) the covalent acyl bond and (ii) a strong salt-bridge involving the carboxylate moiety of the drug. Comparison of the structures of OXA-13 in the apo form and in complex with meropenem revealed an unsuspected flexibility in the region of the essential serine 115 residue, with possible consequences for the catalytic properties of the enzyme. In the apo form, the Ser115 side-chain is oriented outside the active site, whereas the general base Lys70 adopts a conformation that seems to be incompatible with the activation of the catalytic water molecule required for the deacylation step. In the OXA-13:meropenem complex, a 3.5 A movement of the backbone of the 114-116 loop towards the side-chain of Lys70 was observed, which seems to be driven by a displacement of the neighbouring 91-104 loop and which results in the repositioning of the side-chain hydroxyl group of Ser115 toward the catalytic centre. Concomitantly, the side-chain of Lys70 is forced to curve in the direction of the deacylating water molecule, which is then strongly bound and activated by this residue. However, a distance of ca 5 A separates the catalytic water molecule from the acyl carbonyl group of meropenem, a structural feature that accounts for the inhibition of OXA-13 by this drug. Finally

  12. Time-resolved fluorescence anisotropy and fluctuation correlation analysis of major histocompatibility complex class I proteins in fibroblast cells.

    PubMed

    Heikal, Ahmed A

    2014-03-15

    Major histocompatibility complex class I proteins, MHC(I), are expressed in almost all nucleated cells and synthesized in the endoplasmic reticulum (ER). The orientation and mobility of these complexes are crucial in their biological function in the immune system, i.e., the cytosolic pathogen peptides loading and their presentation to T-cell receptors at the plasma membrane, where cell destruction is triggered. Here, we investigate the structural flexibility and associations of GFP-encoded MHC(I) alleles (H2L(d)), namely H2L(d)GFPin and H2L(d)GFPout, in cultured mouse fibroblast cells. Time-resolved fluorescence anisotropy of H2L(d)GFPin in the ER indicates a dominant overall tumbling motion of 56±7 ns (ER), with a fast conformational flexibility, as compared with a restricted rotation of H2L(d)GFPout. At the single-molecule level, the diffusion coefficient of H2L(d)GFPin and H2L(d)GFPout in the ER is (1.8±0.5)×10(-9) and (2.1±0.6)×10(-9) cm(2)/s, respectively, as revealed by fluorescence correlation spectroscopy. A complementary immunoblotting of H2L(d)GFP constructs, isolated from mouse fibroblast cells, reveals band at 75 kDa as compared with 29 kDa of the free EGFP. These real-time dynamics provide new insights into the structural flexibility and intracellular associations of GFP-labeled MHC(I) alleles (H2L(d)) in living cells. PMID:23811298

  13. Characterization of class II β chain major histocompatibility complex genes in a family of Hawaiian honeycreepers: 'amakihi (Hemignathus virens).

    PubMed

    Jarvi, Susan I; Bianchi, Kiara R; Farias, Margaret Em; Txakeeyang, Ann; McFarland, Thomas; Belcaid, Mahdi; Asano, Ashley

    2016-07-01

    Hawaiian honeycreepers (Drepanidinae) have evolved in the absence of mosquitoes for over five million years. Through human activity, mosquitoes were introduced to the Hawaiian archipelago less than 200 years ago. Mosquito-vectored diseases such as avian malaria caused by Plasmodium relictum and Avipoxviruses have greatly impacted these vulnerable species. Susceptibility to these diseases is variable among and within species. Due to their function in adaptive immunity, the role of major histocompatibility complex genes (Mhc) in disease susceptibility is under investigation. In this study, we evaluate gene organization and levels of diversity of Mhc class II β chain genes (exon 2) in a captive-reared family of Hawaii 'amakihi (Hemignathus virens). A total of 233 sequences (173 bp) were obtained by PCR+1 amplification and cloning, and 5720 sequences were generated by Roche 454 pyrosequencing. We report a total of 17 alleles originating from a minimum of 14 distinct loci. We detected three linkage groups that appear to represent three distinct haplotypes. Phylogenetic analysis revealed one variable cluster resembling classical Mhc sequences (DAB) and one highly conserved, low variability cluster resembling non-classical Mhc sequences (DBB). High net evolutionary divergence values between DAB and DBB resemble that seen between chicken BLB system and YLB system genes. High amino acid identity among non-classical alleles from 12 species of passerines (DBB) and four species of Galliformes (YLB) was found, suggesting that these non-classical passerine sequences may be related to the Galliforme YLB sequences. PMID:26971289

  14. Constraints within major histocompatibility complex class I restricted peptides: Presentation and consequences for T-cell recognition

    SciTech Connect

    Theodossis, Alex; Guillonneau, Carole; Welland, Andrew; Ely, Lauren K.; Clements, Craig S.; Williamson, Nicholas A.; Webb, Andrew I.; Wilce, Jacqueline A.; Mulder, Roger J.; Dunstone, Michelle A.; Doherty, Peter C.; McCluskey, James; Purcell, Anthony W.; Turner, Stephen J.; Rossjohn, Jamie

    2010-03-24

    Residues within processed protein fragments bound to major histocompatibility complex class I (MHC-I) glycoproteins have been considered to function as a series of 'independent pegs' that either anchor the peptide (p) to the MHC-I and/or interact with the spectrum of {alpha}{beta}-T-cell receptors (TCRs) specific for the pMHC-I epitope in question. Mining of the extensive pMHC-I structural database established that many self- and viral peptides show extensive and direct interresidue interactions, an unexpected finding that has led us to the idea of 'constrained' peptides. Mutational analysis of two constrained peptides (the HLA B44 restricted self-peptide (B44DP{alpha}-EEFGRAFSF)) and an H2-D{sup b} restricted influenza peptide (D{sup b}PA, SSLENFRAYV) demonstrated that the conformation of the prominently exposed arginine in both peptides was governed by interactions with MHC-I-orientated flanking residues from the peptide itself. Using reverse genetics in a murine influenza model, we revealed that mutation of an MHC-I-orientated residue (SSLENFRAYV {yields} SSLENARAYV) within the constrained PA peptide resulted in a diminished cytotoxic T lymphocyte (CTL) response and the recruitment of a limited pMHC-I specific TCR repertoire. Interactions between individual peptide positions can thus impose fine control on the conformation of pMHC-I epitopes, whereas the perturbation of such constraints can lead to a previously unappreciated mechanism of viral escape.

  15. Trophoblast Major Histocompatibility Complex Class I Expression Is Associated with Immune-Mediated Rejection of Bovine Fetuses Produced by Cloning.

    PubMed

    Rutigliano, Heloisa M; Thomas, Aaron J; Wilhelm, Amanda; Sessions, Benjamin R; Hicks, Brady A; Schlafer, Donald H; White, Kenneth L; Davies, Christopher J

    2016-08-01

    Trophoblast cells from bovine somatic cell nuclear transfer (SCNT) conceptuses express major histocompatibility complex class I (MHC-I) proteins early in gestation, and this may be one cause of the significant first-trimester embryonic mortality observed in these pregnancies. MHC-I homozygous-compatible (n = 9), homozygous-incompatible (n = 8), and heterozygous-incompatible (n = 5) SCNT pregnancies were established. The control group consisted of eight pregnancies produced by artificial insemination. Uterine and placental samples were collected on Day 35 ± 1 of pregnancy, and expression of MHC-I, leukocyte markers, and cytokines were examined by immunohistochemistry. Trophoblast cells from all SCNT pregnancies expressed MHC-I, while trophoblast cells from age-matched control pregnancies were negative for MHC-I expression. Expression of MHC-I antigens by trophoblast cells from SCNT pregnancies was associated with lymphocytic infiltration in the endometrium. Furthermore, MHC-I-incompatible conceptuses, particularly the heterozygous-incompatible ones, induced a more pronounced lymphocytic infiltration than MHC-I-compatible conceptuses. Cells expressing cluster of differentiation (CD) 3, gamma/deltaTCR, and MHC-II were increased in the endometrium of SCNT pregnancies compared to the control group. CD4(+) lymphocytes were increased in MHC-I-incompatible pregnancies compared to MHC-I-compatible and control pregnancies. CD8(+), FOXP3(+), and natural killer cells were increased in MHC-I heterozygous-incompatible SCNT pregnancies compared to homozygous SCNT and control pregnancies. PMID:27385783

  16. Cross-linking staphylococcal enterotoxin A bound to major histocompatibility complex class I is required for TNF-alpha secretion

    NASA Technical Reports Server (NTRS)

    Wright, A. D.; Chapes, S. K.

    1999-01-01

    The mechanism of how superantigens function to activate cells has been linked to their ability to bind and cross-link the major histocompatibility complex class II (MHCII) molecule. Cells that lack the MHCII molecule also respond to superantigens, however, with much less efficiency. Therefore, the purpose of this study was to confirm that staphylococcal enterotoxin A (SEA) could bind the MHCI molecule and to test the hypothesis that cross-linking SEA bound to MHCII-deficient macrophages would induce a more robust cytokine response than without cross-linking. We used a capture enzyme-linked immunosorbent assay and an immunprecipitation assay to directly demonstrate that MHCI molecules bind SEA. Directly cross-linking MHCI using monoclonal antibodies or cross-linking bound SEA with an anti-SEA antibody or biotinylated SEA with avidin increased TNF-alpha and IL-6 secretion by MHCII(-/-) macrophages. The induction of a vigorous macrophage cytokine response by SEA/anti-SEA cross-linking of MHCI offers a mechanism to explain how MHCI could play an important role in superantigen-mediated pathogenesis. Copyright 1999 Academic Press.

  17. In situ detection of autoreactive CD4 T cells in brain and heart using major histocompatibility complex class II dextramers.

    PubMed

    Massilamany, Chandirasegaran; Gangaplara, Arunakumar; Jia, Ting; Elowsky, Christian; Li, Qingsheng; Zhou, You; Reddy, Jay

    2014-01-01

    This report demonstrates the use of major histocompatibility complex (MHC) class II dextramers for detection of autoreactive CD4 T cells in situ in myelin proteolipid protein (PLP) 139-151-induced experimental autoimmune encephalomyelitis (EAE) in SJL mice and cardiac myosin heavy chain-α (Myhc) 334-352-induced experimental autoimmune myocarditis (EAM) in A/J mice. Two sets of cocktails of dextramer reagents were used, where dextramers(+) cells were analyzed by laser scanning confocal microscope (LSCM): EAE, IA(s)/PLP 139-151 dextramers (specific)/anti-CD4 and IA(s)/Theiler's murine encephalomyelitis virus (TMEV) 70-86 dextramers (control)/anti-CD4; and EAM, IA(k)/Myhc 334-352 dextramers/anti-CD4 and IA(k)/bovine ribonuclease (RNase) 43-56 dextramers (control)/anti-CD4. LSCM analysis of brain sections obtained from EAE mice showed the presence of cells positive for CD4 and PLP 139-151 dextramers, but not TMEV 70-86 dextramers suggesting that the staining obtained with PLP 139-151 dextramers was specific. Likewise, heart sections prepared from EAM mice also revealed the presence of Myhc 334-352, but not RNase 43-56-dextramer(+) cells as expected. Further, a comprehensive method has also been devised to quantitatively analyze the frequencies of antigen-specific CD4 T cells in the 'Z' serial images. PMID:25145797

  18. In Situ Detection of Autoreactive CD4 T Cells in Brain and Heart Using Major Histocompatibility Complex Class II Dextramers

    PubMed Central

    Massilamany, Chandirasegaran; Gangaplara, Arunakumar; Jia, Ting; Elowsky, Christian; Li, Qingsheng; Zhou, You; Reddy, Jay

    2014-01-01

    This report demonstrates the use of major histocompatibility complex (MHC) class II dextramers for detection of autoreactive CD4 T cells in situ in myelin proteolipid protein (PLP) 139-151-induced experimental autoimmune encephalomyelitis (EAE) in SJL mice and cardiac myosin heavy chain-α (Myhc) 334-352-induced experimental autoimmune myocarditis (EAM) in A/J mice. Two sets of cocktails of dextramer reagents were used, where dextramers+ cells were analyzed by laser scanning confocal microscope (LSCM): EAE, IAs/PLP 139-151 dextramers (specific)/anti-CD4 and IAs/Theiler’s murine encephalomyelitis virus (TMEV) 70-86 dextramers (control)/anti-CD4; and EAM, IAk/Myhc 334-352 dextramers/anti-CD4 and IAk/bovine ribonuclease (RNase) 43-56 dextramers (control)/anti-CD4. LSCM analysis of brain sections obtained from EAE mice showed the presence of cells positive for CD4 and PLP 139-151 dextramers, but not TMEV 70-86 dextramers suggesting that the staining obtained with PLP 139-151 dextramers was specific. Likewise, heart sections prepared from EAM mice also revealed the presence of Myhc 334-352, but not RNase 43-56-dextramer+ cells as expected. Further, a comprehensive method has also been devised to quantitatively analyze the frequencies of antigen-specific CD4 T cells in the ‘Z’ serial images. PMID:25145797

  19. Deacylation Mechanism and Kinetics of Acyl-Enzyme Complex of Class C β-Lactamase and Cephalothin.

    PubMed

    Tripathi, Ravi; Nair, Nisanth N

    2016-03-17

    Understanding the molecular details of antibiotic resistance by the bacterial enzymes β-lactamases is vital for the development of novel antibiotics and inhibitors. In this spirit, the detailed mechanism of deacylation of the acyl-enzyme complex formed by cephalothin and class C β-lactamase is investigated here using hybrid quantum-mechanical/molecular-mechanical molecular dynamics methods. The roles of various active-site residues and substrate in the deacylation reaction are elucidated. We identify the base that activates the hydrolyzing water molecule and the residue that protonates the catalytic serine (Ser64). Conformational changes in the active sites and proton transfers that potentiate the efficiency of the deacylation reaction are presented. We have also characterized the oxyanion holes and other H-bonding interactions that stabilize the reaction intermediates. Together with the kinetic and mechanistic details of the acylation reaction, we analyze the complete mechanism and the overall kinetics of the drug hydrolysis. Finally, the apparent rate-determining step in the drug hydrolysis is scrutinized. PMID:26918257

  20. Small organic compounds enhance antigen loading of class II major histocompatibility complex proteins by targeting the polymorphic P1 pocket.

    PubMed

    Höpner, Sabine; Dickhaut, Katharina; Hofstätter, Maria; Krämer, Heiko; Rückerl, Dominik; Söderhäll, J Arvid; Gupta, Shashank; Marin-Esteban, Viviana; Kühne, Ronald; Freund, Christian; Jung, Günther; Falk, Kirsten; Rötzschke, Olaf

    2006-12-15

    Major histocompatibility complex (MHC) molecules are a key element of the cellular immune response. Encoded by the MHC they are a family of highly polymorphic peptide receptors presenting peptide antigens for the surveillance by T cells. We have shown that certain organic compounds can amplify immune responses by catalyzing the peptide loading of human class II MHC molecules HLA-DR. Here we show now that they achieve this by interacting with a defined binding site of the HLA-DR peptide receptor. Screening of a compound library revealed a set of adamantane derivatives that strongly accelerated the peptide loading rate. The effect was evident only for an allelic subset and strictly correlated with the presence of glycine at the dimorphic position beta86 of the HLA-DR molecule. The residue forms the floor of the conserved pocket P1, located in the peptide binding site of MHC molecule. Apparently, transient occupation of this pocket by the organic compound stabilizes the peptide-receptive conformation permitting rapid antigen loading. This interaction appeared restricted to the larger Gly(beta86) pocket and allowed striking enhancements of T cell responses for antigens presented by these "adamantyl-susceptible" MHC molecules. As catalysts of antigen loading, compounds targeting P1 may be useful molecular tools to amplify the immune response. The observation, however, that the ligand repertoire can be affected through polymorphic sites form the outside may also imply that environmental factors could induce allergic or autoimmune reactions in an allele-selective manner. PMID:17005558

  1. Genetic variation of the major histocompatibility complex (MHC class II B gene) in the threatened Hume's pheasant, Syrmaticus humiae.

    PubMed

    Chen, Weicai; Bei, Yongjian; Li, Hanhua

    2015-01-01

    Major histocompatibility complex (MHC) genes are the most polymorphic genes in vertebrates and encode molecules that play a crucial role in pathogen resistance. As a result of their diversity, they have received much attention in the fields of evolutionary and conservation biology. Here, we described the genetic variation of MHC class II B (MHCIIB) exon 2 in a wild population of Hume's pheasant (Syrmaticus humiae), which has suffered a dramatic decline in population over the last three decades across its ranges in the face of heavy exploitation and habitat loss. Twenty-four distinct alleles were found in 73 S. humiae specimens. We found seven shared alleles among four geographical groups as well as six rare MHCIIB alleles. Most individuals displayed between one to five alleles, suggesting that there are at least three MHCIIB loci of the Hume's pheasant. The dN ⁄ dS ratio at putative antigen-binding sites (ABS) was significantly greater than one, indicating balancing selection is acting on MHCIIB exon 2. Additionally, recombination and gene conversion contributed to generating MHCIIB diversity in the Hume's pheasant. One to three recombination events and seventy-five significant gene conversion events were observed within the Hume's pheasant MHCIIB loci. The phylogenetic tree and network analysis revealed that the Hume's pheasant alleles do not cluster together, but are scattered through the tree or network indicating a trans-species evolutionary mode. These findings revealed the evolution of the Hume's pheasant MHC after suffering extreme habitat fragmentation. PMID:25629763

  2. Relationship between target antigens and major histocompatibility complex (MHC) class II genes in producing two pathogenic antibodies simultaneously

    PubMed Central

    Zakka, L R; Keskin, D B; Reche, P; Ahmed, A R

    2010-01-01

    In this report, we present 15 patients with histological and immunopathologically proven pemphigus vulgaris (PV). After a mean of 80 months since the onset of disease, when evaluated serologically, they had antibodies typical of PV and pemphigoid (Pg). Similarly, 18 patients with bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP) were diagnosed on the basis of histology and immunopathology. After a mean of 60 months since the onset of disease, when their sera were evaluated they were found to have Pg and PV autoantibodies. In both groups of patients the diseases were characterized by a chronic course, which included several relapses and recurrences and were non-responsive to conventional therapy. The major histocompatibility complex class II (MHC II) genes were studied in both groups of patients and phenotypes associated typically with them were observed. Hence, in 33 patients, two different pathogenic autoantibodies were detected simultaneously. The authors provide a computer model to show that each MHC II gene has relevant epitopes that recognize the antigens associated with both diseases. Using the databases in these computer models, the authors present the hypothesis that these two autoantibodies are produced simultaneously due to the phenomena of epitope spreading. PMID:21069937

  3. Inhibition of Class II Major Histocompatibility Complex Antigen Processing by Escherichia coli Heat-Labile Enterotoxin Requires an Enzymatically Active A Subunit

    PubMed Central

    Matousek, Milita P.; Nedrud, John G.; Cieplak, Witold; Harding, Clifford V.

    1998-01-01

    Escherichia coli heat-labile enterotoxin (LT) and cholera toxin (CT) were found to inhibit intracellular antigen processing. Processing was not inhibited by mutant LT with attenuated ADP-ribosyltransferase activity, CT B or LT B subunit, which enhanced presentation of preexisting cell surface peptide-class II major histocompatibility complex complexes. Inhibition of antigen processing correlated with A subunit ADP-ribosyltransferase activity. PMID:9632629

  4. Activation of cytomegalovirus-specific CD8+ T-cell response by antibody-mediated peptide-major histocompatibility class I complexes

    PubMed Central

    Schmittnaegel, Martina; Klein, Christian; Levitsky, Victor; Knoetgen, Hendrik

    2016-01-01

    Imposing antigenicity on tumor cells is a key step toward successful cancer-immunotherapy. A cytomegalovirus-derived peptide recombinantly fused to a major histocompatibility class I complex and a monoclonal antibody can be targeted to tumor cells by antibody-mediated delivery and activate a strong and specific CD8+ T cell response. PMID:26942061

  5. Major histocompatibility complex class I expression on neurons in subacute sclerosing panencephalitis and experimental subacute measles encephalitis

    SciTech Connect

    Gogate, N.; Yamabe, Toshio; Verma, L.; Dhib-Jalbut, S.

    1996-04-01

    Lack of major histocompatibility class I antigens on neurons has been implicated as a possible mechanism for viral persistence in the brain since these antigens are required for cytotoxic T-lymphocyte recognition of infected cells. In subacute sclerosing panencephalitis (SSPE), measles virus (MV) persists in neurons, resulting in a fatal chronic infection. MHC class I mRNA expression was examined in formalin-fixed brain tissue from 6 SSPE patients by in situ hybridization. In addition MHC class I protein expression in MV-infected neurons was examined in experimental Subacute Measles Encephalitis (SME) by double immunohistochemistry. MHC class I mRNA expression was found to be upregulated in SSPE tissues studied, and in 5 out of 6 cases the expression was definitively seen on neurons. The percentage of neurons expressing MHC class I mRNA ranged between 20 to 84% in infected areas. There was no correlation between the degree of infection and expression of MHC class I molecules on neurons. Importantly, the number of neurons co-expressing MHC class I and MV antigens was markedly low, varying between 2 to 8%. Similar results were obtained in SME where 20 to 30% of the neurons expressed MHC class I but < 8% co-expressed MHC class I and MV antigens. Perivascular infiltrating cells in the infected regions in SME expressed IFN{gamma} immunoreactivity. The results suggest that MV may not be directly involved in the induction of MHC class I on neurons and that cytokines such as IFN{gamma} may play an important role. Furthermore, the paucity of neurons co-expressing MHC class I and MV antigens in SSPE and SME suggests that such cells are either rapidly cleared by cytotoxic T lymphocytes (CTL), or, alternatively, lack of co-expression of MHC class I on MV infected neurons favors MV persistence in these cells by escaping CTL recognition. 33 refs., 3 figs., 3 tabs.

  6. Major histocompatibility complex class II (DR) antigen and costimulatory molecules on in vitro and in vivo activated human polymorphonuclear neutrophils

    PubMed Central

    Sandilands, Gavin P; McCrae, Jame; Hill, Kathryn; Perry, Martin; Baxter, Derek

    2006-01-01

    We have previously shown that normal human peripheral blood polymorphonuclear neutrophils (PMNs) contain cytoplasmic ‘stores’ of three key molecules normally associated with antigen presentation and T-cell costimulation, i.e. major histocompatibility complex class II (DR) antigen, CD80 (B7-1) and CD86 (B7-2). These cytoplasmic molecules were found to translocate to the cell surface within a few minutes following cross-linking (X-L) of Mac-1: an early neutrophil activation signal. In this study we have compared X-L of Mac −1 in parallel with four other well documented in vitro neutrophil activators: phorbol myristate acetate, N-formyl methionyl leucyl phenylalanine, lipopolysaccharide, and phagocytosis of immunoglobulin G–Latex particles. In addition, we have used paired samples of neutrophils obtained from peripheral blood (as a control) and synovial fluid from patients with rheumatoid arthritis as a source of in vivo activated cells. With the exception of phagocytosis, all activators resulted in the rapid (within 30 min) generation of two populations of activated neutrophils (designated P1 and P2) based on flow-cytometry measurements of size, granularity and phenotype. Significant up-regulation of DR and costimulatory molecules was observed, predominantly on P2 cells, with all activators except phagocytosis. CD80 and CD86 were noted to respond to the various activation signals in a different pattern suggesting that their intracellular granule location may be different. Dual-staining confocal laser microscopy studies showed that CD80 is largely confined to secretory vesicles (SVs) while CD86 appears to have a much wider distribution being found in SVs and within secondary (specific) and primary (azurophilic) granules. Increased surface expression of these antigens was also observed on P2 synovial fluid neutrophils appearing as large heterogeneous clusters on the cell surface when visualized by confocal laser microscopy. PMID:17034427

  7. Murine cytomegalovirus perturbs endosomal trafficking of major histocompatibility complex class I molecules in the early phase of infection.

    PubMed

    Tomas, Maja Ilić; Kucić, Natalia; Mahmutefendić, Hana; Blagojević, Gordana; Lucin, Pero

    2010-11-01

    Murine cytomegalovirus (MCMV) functions interfere with protein trafficking in the secretory pathway. In this report we used Δm138-MCMV, a recombinant virus with a deleted viral Fc receptor, to demonstrate that MCMV also perturbs endosomal trafficking in the early phase of infection. This perturbation had a striking impact on cell surface-resident major histocompatibility complex class I (MHC-I) molecules due to the complementary effect of MCMV immunoevasins, which block their egress from the secretory pathway. In infected cells, constitutively endocytosed cell surface-resident MHC-I molecules were arrested and retained in early endosomal antigen 1 (EEA1)-positive and lysobisphosphatidic acid (LBPA)-negative perinuclear endosomes together with clathrin-dependent cargo (transferrin receptor, Lamp1, and epidermal growth factor receptor). Their progression from these endosomes into recycling and degradative routes was inhibited. This arrest was associated with a reduction of the intracellular content of Rab7 and Rab11, small GTPases that are essential for the maturation of recycling and endolysosomal domains of early endosomes. The reduced recycling of MHC-I in Δm138-MCMV-infected cells was accompanied by their accelerated loss from the cell surface. The MCMV function that affects cell surface-resident MHC-I was activated in later stages of the early phase of viral replication, after the expression of known immunoevasins. MCMV without the three immunoevasins (the m04, m06, and m152 proteins) encoded a function that affects endosomal trafficking. This function, however, was not sufficient to reduce the cell surface expression of MHC-I in the absence of the transport block in the secretory pathway. PMID:20719942

  8. Inflammatory bowel diseases influence major histocompatibility complex class I (MHC I) and II compartments in intestinal epithelial cells.

    PubMed

    Bär, F; Sina, C; Hundorfean, G; Pagel, R; Lehnert, H; Fellermann, K; Büning, J

    2013-05-01

    Antigen presentation by intestinal epithelial cells (IEC) is crucial for intestinal homeostasis. Disturbances of major histocompatibility complex class I (MHC I)- and II-related presentation pathways in IEC appear to be involved in an altered activation of CD4(+) and CD8(+) T cells in inflammatory bowel disease. However, a comprehensive analysis of MHC I- and II-enriched compartments in IEC of the small and large bowel in the healthy state as opposed to inflammatory bowel diseases is lacking. The aim of this study was to characterize the subcellular expression of MHC I and II in the endocytic pathway of IEC throughout all parts of the intestinal tract, and to identify differences between the healthy state and inflammatory bowel diseases. Biopsies were taken by endoscopy from the duodenum, jejunum, ileum and colon in healthy individuals (n = 20). In Crohn's disease (CD), biopsies were obtained from the ileum and colon and within the colon from ulcerative colitis (UC) patients (n = 15). Analysis of IEC was performed by immunoelectron microscopy. MHC I and II were identified in early endosomes and multi-vesicular, multi-lamellar, electrondense and vacuolar late endosomes. Both molecules were enriched in multi-vesicular bodies. No differences were found between the distinct parts of the gut axis. In CD and UC the expression of MHC I and II showed a shift from multi-vesicular bodies towards the basolateral membranes. Within the multi-vesicular bodies, MHC I and II moved from internal vesicles to the limiting membranes upon inflammation in CD and UC. MHC I- and II-enriched compartments in IEC were identical in all parts of the small and large bowel. CD and UC appear to modulate the MHC I- and II-related presentation pathways of exogenous antigens in IEC. PMID:23574324

  9. Localization of major histocompatibility complex class II molecules in phagolysosomes of murine macrophages infected with Leishmania amazonensis.

    PubMed Central

    Antoine, J C; Jouanne, C; Lang, T; Prina, E; de Chastellier, C; Frehel, C

    1991-01-01

    Leishmania-infected macrophages are potential antigen-presenting cells for CD4+ T lymphocytes, which recognize parasite antigens bound to major histocompatibility complex class II molecules (Ia). However, the intracellular sites where Ia and antigens may interact are far from clear, since parasites grow within the modified lysosomal compartment of the host cell, whereas Ia molecules seem to be targeted to endosomes. To address this question, the expression and fate of Ia molecules were studied by immunocytochemistry in Leishmania amazonensis-infected murine macrophages stimulated with gamma interferon. In uninfected macrophages, Ia molecules were localized on the plasma membrane and in perinuclear vesicles, but they underwent a dramatic redistribution after infection, since most of the intracellular staining was then associated with the periphery of the parasitophorous vacuoles (p.v.) and quite often polarized towards amastigote-binding sites. The Ii invariant chain, which is transiently associated with Ia during their intracellular transport, although well expressed in infected macrophages, apparently did not reach the p.v. Similar findings were observed with macrophages from mice either resistant or highly susceptible to Leishmania infection. In order to determine the origin of p.v.-associated Ia, the fate of plasma membrane, endosomal, and lysosomal markers, detected with specific antibodies, was determined after infection. At 48 h after infection, p.v. was found to exhibit a membrane composition typical of mature lysosomes. Overall, these data suggest that (i) Ia located in p.v. originate from secondary lysosomes involved in the biogenesis of this compartment or circulate in several endocytic organelles, including lysosomes and (ii) p.v. could play a role in antigen processing and presentation. Alternatively, the presence of high amounts of Ia in p.v. could be due to a Leishmania-induced mechanism by means of which this organism may evade the immune response

  10. Role of major histocompatibility complex class II in resistance of mice to naturally acquired infection with Syphacia obvelata

    NASA Technical Reports Server (NTRS)

    Stewart, Patricia W.; Chapes, Stephen K.

    2003-01-01

    Genetics plays a substantial role in host resistance in many host-parasite interactions. We examined the prevalence of naturally acquired infection with Syphacia obvelata in a number of mouse strains housed in a non-barrier facility. These mice, which included cross-bred and congenic, inbred strains on various genetic backgrounds, differ in the loci for the immune function genes--major histocompatibility complex class II (MHCII), toll-like receptor 4 (Tlr4), and solute carrier family 11, member 1 (Slc11a1)--which allowed comparisons of the impact of these genes on resistance to pinworm infection. Male and female mice of various ages were sampled over an 18-month period; infection was determined by use of the cellophane tape test. Results indicated that mice that were MHCII+/+ had a significantly lower prevalence of infection than did mice that were MHCII-/-. Differences were not seen between male and female mice. Although MHCII+/+ mice had an age-associated decrease in infection prevalence, such decrease was not seen in MHCII-/- mice. In contrast, infection prevalence in mice with the normal Tlr4 gene (Tlr4(LPS-n/LPS-n)) gene did not differ significantly compared with that in mice that were homozygous for either the point mutation (Tlr4(LPS-d/LPS-d)) or deletion (Tlr4(LPS-del/LPS-del)) of that gene. Likewise, the presence (Sle11a1r/r) or absence (Slc11a1s/s) of functional alleles for Slc11a1 had no effect on the prevalence of infection with S. obvelata. In conclusion, presence of MHCII, but not Tlr4 or Slc11a1 significantly influences prevalence of naturally acquired infection with S. obvelata. These data justify further comprehensive analyses of the immune components that are involved in pinworm resistance.

  11. Full solution, for crystal class 3m, of the Holland-EerNisse complex material-constant theory of lossy piezoelectrics for harmonic time dependence.

    PubMed

    Piquette, Jean C; McLaughlin, Elizabeth A

    2007-06-01

    A complex material-constant theory of lossy piezoelectrics is fully solved for crystal class 3m for harmonic time dependence of the fields and stresses. A new demonstration that the theory's eigen coupling factor equation applies to the lossy alternating current (AC) case also is given. The solution presented for crystal class 3m provides a complete orthonormal set of eigenvectors and eigenvalues for the eigen coupling factor problem, and it also provides a complete orthonormal set of eigenvectors and eigenvalues for the eigen loss tangent problem, for this crystal class. It is shown that two positive coupling factors are sufficient to express an arbitrary 3m crystal state. Despite the complex nature of the material constants, the Holland-EerNisse theory produces fully real expressions for the coupling factors. The loss tangent eigenvalues also are fully real and positive. The loss eigenstates are important because driving a crystal in a loss eigenstate tends to minimize the impact of material losses. Given also is a set of loss inequalities for crystal class 3m. The loss inequalities of crystal class 6mm are recovered from these when d22 and s(E)14 both vanish. PMID:17571823

  12. Constitutive expression of major histocompatibility complex class II antigens in pulmonary epithelium and endothelium varies among different species.

    PubMed

    Houser, Stuart L; Benjamin, Louis C; Wain, John C; Madsen, Joren C; Allan, James S

    2004-02-27

    We have observed high constitutive levels of class II antigen expression on porcine and human coronary endothelium, but not on the endothelium of rats and mice. This study examines whether a similar interspecies difference exists in the expression of class II molecules on pulmonary epithelium and endothelium. Lung tissues from naïve human, porcine, and rodent sources were stained with the monoclonal antibody ISCR3 and examined by light microscopy. Immunoperoxidase staining of class II molecules was observed on human and porcine pulmonary epithelium and endothelium, but was absent in rats and mice. By using an antibody with cross-species reactivity, we demonstrated that naïve swine pulmonary epithelium and endothelium, unlike those of rodent species, express basal levels of class II antigens in a manner similar to that observed in human lung tissue. These interspecies differences may explain experimental differences observed between murine and large-animal constructs. PMID:15084944

  13. Endoplasmic reticulum aminopeptidase 1 function and its pathogenic role in regulating innate and adaptive immunity in cancer and major histocompatibility complex class I-associated autoimmune diseases.

    PubMed

    Fruci, D; Romania, P; D'Alicandro, V; Locatelli, F

    2014-08-01

    Major histocompatibility complex (MHC) class I molecules present antigenic peptides on the cell surface to alert natural killer (NK) cells and CD8(+) T cells for the presence of abnormal intracellular events, such as virus infection or malignant transformation. The generation of antigenic peptides is a multistep process that ends with the trimming of N-terminal extensions in the endoplasmic reticulum (ER) by aminopeptidases ERAP1 and ERAP2. Recent studies have highlighted the potential role of ERAP1 in reprogramming the immunogenicity of tumor cells in order to elicit innate and adaptive antitumor immune responses, and in conferring susceptibility to autoimmune diseases in predisposed individuals. In this review, we will provide an overview of the current knowledge about the role of ERAP1 in MHC class I antigen processing and how its manipulation may constitute a promising tool for cancer immunotherapy and treatment of MHC class I-associated autoimmune diseases. PMID:25066018

  14. Effective suppression of class I major histocompatibility complex expression by the US11 or ICP47 genes can be limited by cell type or interferon-gamma exposure.

    PubMed

    Radosevich, Thomas J; Seregina, Tatiana; Link, Charles J

    2003-12-10

    An impediment encountered in many viral-based gene therapy clinical trials has been the rapid destruction of the transgene by the host's immune response. The processing and presentation of antigens through the class I major histocompatibility complex (MHC) pathway is the initial specific response to viral infection. Disruption of the class I MHC pathway by herpes simplex virus (HSV) or the human cytomegalovirus (HCMV) results in a decrease of the CD8(+) cytotoxic T lymphocyte (CTL) response and prolongs survival of infected cells in the host. Two viral immune suppression genes that interfere with the class I MHC presentation pathway, the HSV type I ICP47 gene and HCMV US11 gene, were cloned and each incorporated into a retroviral vector. HSV ICP47 and HCMV US11 transgenes were expressed in multiple cells lines and compared for their abilities to reduce antigen presentation on the cell surface by class I MHC. Retroviral supernatants were used to transduce human, canine, and rat cell lines. Fluorescence-activated cell sorter (FACS) analysis of US11- and ICP47-transduced cell lines demonstrated substantial reductions in class I MHC cell surface expression in most cell lines except in rodent cells where ICP47 is nonfunctional. The decrease in the level of class I MHC expression for ICP47 transduced cell lines ranged from 31-98% relative to negative controls. US11 decreased class I cell surface MHC by 67-96%. When both ICP47 and US11 are expressed in human cells, a further reduction of class I MHC was observed. Next, human A375 melanoma cells were tested to determine if the resulting reduction in cell surface class I MHC would reduce in vitro cytotoxicity by CTL. A375 cells expressing either ICP47 or US11 demonstrated a twofold to threefold reduction of specific lysis by primed CD8(+) CTL. These data clearly establish an ability to convey immune protection to human cells by viral genes. However, further analysis demonstrated that interferon (IFN)-gamma could reverse

  15. Major histocompatibility complex class II dextramers: New tools for the detection of antigen-specific, CD4 T cells in basic and clinical research

    PubMed Central

    Massilamany, Chandirasegaran; Krishnan, Bharathi; Reddy, Jay

    2015-01-01

    The advent of major histocompatibility complex (MHC) tetramer technology has been a major contribution to T cell immunology, because tetramer reagents permit detection of antigen-specific T cells at the single-cell level in heterogeneous populations by flow cytometry. However, unlike MHC class I tetramers, the utility of MHC class II tetramers has been less frequently reported. MHC class II tetramers can be used successfully to enumerate the frequencies of antigen-specific CD4 T cells in cells activated in vitro, but their use for ex vivo analyses continues to be a problem, due in part to their activation dependency for binding with T cells. To circumvent this problem, we recently reported the creation of a new generation of reagents called MHC class II dextramers, which were found to be superior to their counterparts. In this review, we discuss the utility of class II dextramers vis-a-vis tetramers, with respect to their specificity and sensitivity, including potential applications and limitations. PMID:26207337

  16. Herpes B Virus, Macacine Herpesvirus 1, Breaks Simplex Virus Tradition via Major Histocompatibility Complex Class I Expression in Cells from Human and Macaque Hosts

    PubMed Central

    Vasireddi, Mugdha

    2012-01-01

    B virus of the family Herpesviridae is endemic to rhesus macaques but results in 80% fatality in untreated humans who are zoonotically infected. Downregulation of major histocompatibility complex (MHC) class I in order to evade CD8+ T-cell activation is characteristic of most herpesviruses. Here we examined the cell surface presence and total protein expression of MHC class I molecules in B virus-infected human foreskin fibroblast cells and macaque kidney epithelial cells in culture, which are representative of foreign and natural host initial target cells of B virus. Our results show <20% downregulation of surface MHC class I molecules in either type of host cells infected with B virus, which is statistically insignificantly different from that observed in uninfected cells. We also examined the surface expression of MHC class Ib molecules, HLA-E and HLA-G, involved in NK cell inhibition. Our results showed significant upregulation of HLA-E and HLA-G in host cells infected with B virus relative to the amounts observed in other herpesvirus-infected cells. These results suggest that B virus-infected cell surfaces maintain normal levels of MHC class Ia molecules, a finding unique among simplex viruses. This is a unique divergence in immune evasion for B virus, which, unlike human simplex viruses, does not inhibit the transport of peptides for loading onto MHC class Ia molecules because B virus ICP47 lacks a transporter-associated protein binding domain. The fact that MHC class Ib molecules were significantly upregulated has additional implications for host-pathogen interactions. PMID:22973043

  17. Diverse repertoire of the MHC class II-peptide complexes is required for presentation of viral superantigens.

    PubMed

    Golovkina, T; Agafonova, Y; Kazansky, D; Chervonsky, A

    2001-02-15

    Among other features, peptides affect MHC class II molecules, causing changes in the binding of bacterial superantigens (b-Sag). Whether peptides can alter binding of viral superantigens (v-Sag) to MHC class II was not known. Here we addressed the question of whether mutations limiting the diversity of peptides bound by the MHC class II molecules influenced the presentation of v-Sag and, subsequently, the life cycle of the mouse mammary tumor virus (MMTV). T cells reactive to v-Sag were found in mice lacking DM molecules as well as in A(b)Ep-transgenic mice in which MHC class II binding grooves were predominantly occupied by an invariant chain fragment or Ealpha(52-68) peptide, respectively. APCs from the mutant mice failed to present v-Sag, as determined by the lack of Sag-specific T cell activation, Sag-induced T cell deletion, and by the aborted MMTV infection. In contrast, mice that express I-A(b) with a variety of bound peptides presented v-Sag and were susceptible to MMTV infection. Comparison of v-Sag and b-Sag presentation by the same mutant cells suggested that presentation of v-Sag had requirements similar to that for presentation of toxic shock syndrome toxin-1. Thus, MHC class II peptide repertoire is critical for recognition of v-Sag by the T cells and affects the outcome of infection with a retrovirus. PMID:11160278

  18. Class-First Analysis in a Continuum: An Approach to the Complexities of Schools, Society, and Insurgent Science

    ERIC Educational Resources Information Center

    Valdiviezo, Laura Alicia

    2010-01-01

    This essay addresses Katherine Richardson Bruna's paper: "Mexican Immigrant Transnational Social Capital and Class Transformation: Examining the Role of Peer Mediation in Insurgent Science", through five main points. First, I offer a comparison between the traditional analysis of classism in Latin America and Richardson Bruna's call for a…

  19. Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds; Synthesis, characterization and biological evolution

    NASA Astrophysics Data System (ADS)

    Kumar Naik, K. H.; Selvaraj, S.; Naik, Nagaraja

    2014-10-01

    Present work reviews that, the synthesis of (E)-N";-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M2+L]X2, where M2+ = Mn, Co, Ni, Cu, Sr and Cd, L = (7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X = Cl-. Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective α-glucosidase inhibitory activity than free Schiff base ligand.

  20. Cloning and modeling of CD8 beta in the amphibian ambystoma Mexicanum. Evolutionary conserved structures for interactions with major histocompatibility complex (MHC) class I molecules.

    PubMed

    Fellah, Julien S; Tuffèry, Pierre; Etchebest, Catherine; Guillet, Françoise; Bleux, Christian; Charlemagne, Jacques

    2002-04-17

    Mammalian and avian T-cells exhibit a large number of well characterized surface molecules associated with their maturation degree. Very little is known in comparison with T-cell differentiation in ectothermic vertebrates. This is mainly due to the lack of probes to identify T-cell subsets. We cloned and sequenced the first ectothermic CD8 beta DNA complementary to RNA from an amphibian species, the Mexican axolotl. The CD8 beta chain was 30-36% identical with its avian and mammalian homologues. The extracellular V-like domain contained the two typically conserved cysteines and was followed by a J-like sequence containing the canonical Phe-Gly-X-Gly stretch. The connecting peptide was much longer than in other species and contained potential O-glycosylation sites. The axolotl CD8 beta and major histocompatibility complex class I molecules were modeled using human HLA-A2/CD8 alphaalpha complex as template. The backbone conformation of axolotl CD8 beta matched well with the CD8 alpha-2 subunit of the human complex but significant structural differences were located in the CDR1, CDR2 and DE loops. Both axolotl and human class I showed large negative surface potential. The interacting area of the human CD8 alpha chain and of the corresponding region of axolotl CD8 beta had positive electrostatic potential compatible with complexation with the corresponding class I molecules. The presence of a CD8 beta homologue in an amphibian species implies that it was already present in the Devonian ancestor of amphibians and mammals, i.e. more than 400 million years ago. PMID:12034498

  1. Gene Conversion in the Evolution of Both the H-2 and Qa Class I Genes of the Murine Major Histocompatibility Complex

    PubMed Central

    Kuhner, M.; Watts, S.; Klitz, W.; Thomson, G.; Goodenow, R. S.

    1990-01-01

    In order to better understand the role of gene conversion in the evolution of the class I gene family of the major histocompatibility complex (MHC), we have used a computer algorithm to detect clustered sequence similarities among 24 class I DNA sequences from the H-2, Qa, and Tla regions of the murine MHC. Thirty-four statistically significant clusters were detected; individual analysis of the clusters suggested at least 25 past gene conversion or recombination events. These clusters are comparable in size to the conversions observed in the spontaneously occurring H-2K(bm) and H-2K(km2) mutations, and are distributed throughout all exons of the class I gene. Thus, gene conversion does not appear to be restricted to the regions of the class I gene encoding their antigen-presentation function. Moreover, both the highly polymorphic H-2 loci and the relatively monomorphic Qa and Tla loci appear to have participated as donors and recipients in conversion events. If gene conversion is not limited to the highly polymorphic loci of the MHC, then another factor, presumably natural selection, must be responsible for maintaining the observed differences in level of variation. PMID:2076814

  2. Migration-related health inequalities: showing the complex interactions between gender, social class and place of origin.

    PubMed

    Malmusi, Davide; Borrell, Carme; Benach, Joan

    2010-11-01

    In this paper, we briefly review theories and findings on migration and health from the health equity perspective, and then analyse migration-related health inequalities taking into account gender, social class and migration characteristics in the adult population aged 25-64 living in Catalonia, Spain. On the basis of the characterisation of migration types derived from the review, we distinguished between immigrants from other regions of Spain and those from other countries, and within each group, those from richer or poorer areas; foreign immigrants from low-income countries were also distinguished according to duration of residence. Further stratification by sex and social class was applied. Groups were compared in relation to self-assessed health in two cross-sectional population-based surveys, and in relation to indicators of socio-economic conditions (individual income, an index of material and financial assets, and an index of employment precariousness) in one survey. Social class and gender inequalities were evident in both health and socio-economic conditions, and within both the native and immigrant subgroups. Migration-related health inequalities affected both internal and international immigrants, but were mainly limited to those from poor areas, were generally consistent with their socio-economic deprivation, and apparently more pronounced in manual social classes and especially for women. Foreign immigrants from poor countries had the poorest socio-economic situation but relatively better health (especially men with shorter length of residence). Our findings on immigrants from Spain highlight the transitory nature of the 'healthy immigrant effect', and that action on inequality in socio-economic determinants affecting migrant groups should not be deferred. PMID:20869798

  3. A step-by-step overview of the dynamic process of epitope selection by major histocompatibility complex class II for presentation to helper T cells.

    PubMed

    Sadegh-Nasseri, Scheherazade

    2016-01-01

    T cell antigen receptors (TCRs) expressed on cytotoxic or helper T cells can only see their specific target antigen as short sequences of peptides bound to the groove of proteins of major histocompatibility complex (MHC) class I, and class II respectively. In addition to the many steps, several participating proteins, and multiple cellular compartments involved in the processing of antigens, the MHC structure, with its dynamic and flexible groove, has perfectly evolved as the underlying instrument for epitope selection. In this review, I have taken a step-by-step, and rather historical, view to describe antigen processing and determinant selection, as we understand it today, all based on decades of intense research by hundreds of laboratories. PMID:27347387

  4. Localization of major histocompatibility complex class I and II mRNA in human first-trimester chorionic villi by in situ hybridization.

    PubMed

    Lata, J A; Tuan, R S; Shepley, K J; Mulligan, M M; Jackson, L G; Smith, J B

    1992-04-01

    Maternal immune recognition of pregnancy occurs despite the nonexpression of classical major histocompatibility complex (MHC) antigenic determinants by chorionic villous trophoblast, which comprise the major surface area where maternal blood contacts fetal-derived cells. cDNA-mRNA in situ hybridization was used to probe expression of transcripts corresponding to nonpolymorphic MHC determinants in first-trimester chorionic villus samples. The HLA-B7 probe hybridization signals were localized to syncytiotrophoblast and to cells of the mesenchyme but not to villous cytotrophoblast. HLA-G mRNA was found only in syncytiotrophoblast. A DR beta clone hybridized to both villous cytotrophoblast and syncytiotrophoblast. The results suggest that expression of trophoblast class I and class II determinants early in gestation (10 wk) may be regulated by posttranscriptional events. This also suggests the potential for maternal antifetal alloimmune responses. PMID:1552281

  5. A step-by-step overview of the dynamic process of epitope selection by major histocompatibility complex class II for presentation to helper T cells

    PubMed Central

    Sadegh-Nasseri, Scheherazade

    2016-01-01

    T cell antigen receptors (TCRs) expressed on cytotoxic or helper T cells can only see their specific target antigen as short sequences of peptides bound to the groove of proteins of major histocompatibility complex (MHC) class I, and class II respectively. In addition to the many steps, several participating proteins, and multiple cellular compartments involved in the processing of antigens, the MHC structure, with its dynamic and flexible groove, has perfectly evolved as the underlying instrument for epitope selection. In this review, I have taken a step-by-step, and rather historical, view to describe antigen processing and determinant selection, as we understand it today, all based on decades of intense research by hundreds of laboratories. PMID:27347387

  6. Complex phenotypic and genotypic responses of Listeria monocytogenes strains exposed to the class IIa bacteriocin sakacin P.

    PubMed

    Tessema, Girum Tadesse; Møretrø, Trond; Kohler, Achim; Axelsson, Lars; Naterstad, Kristine

    2009-11-01

    Sakacin P is a class IIa bacteriocin that is active against the food-borne pathogen Listeria monocytogenes, and use of this compound as a biopreservative in foods has been suggested. In the present study, we characterized 30 spontaneous sakacin P-resistant mutants of L. monocytogenes obtained after single exposure to sakacin P. The frequency of development of sakacin P resistance for all strains was in the range from 10(-8) to 10(-9). Using the 50% inhibitory concentration (IC(50)) of sakacin P, the strains could be grouped into strains with high levels of resistance (IC(50), > or =10(4) ng ml(-1)) and strains with low levels of resistance (IC(50), <10(4) ng ml(-1)). Resistant strains belonging to the same IC(50) group also had similar physiological and genetic characteristics. Generally, the resistant strains showed substantial variations in many parameters, such as differences in the stability of the acquired resistance to sakacin P, growth fitness, food-related stress tolerance, and biofilm-forming ability. Fourier transform infrared spectroscopy revealed differences between wild-type and resistant strains in polysaccharide, fatty acid, and, protein regions. A mannose-specific phosphotransferase (PTS) operon has been described for class IIa bacteriocin resistance, and the sakacin P-resistant strains displayed both up- and downregulation of the expression of the mptA gene encoding the PTS system. This is the first comprehensive study of the diversity of a large number of spontaneous resistant mutants obtained after one exposure to a class IIa bacteriocin, particularly to sakacin P. The great diversity among the resistant strains exposed to the same stress conditions suggests that there are different resistance mechanisms. PMID:19767478

  7. Evidence for a trans-acting factor that regulates the transcription of class II major histocompatibility complex genes: genetic and functional analysis.

    PubMed Central

    Calman, A F; Peterlin, B M

    1988-01-01

    The study of specific trans-acting transcription factors in prokaryotes and lower eukaryotes has been greatly facilitated by genetic analysis of mutant strains deficient in such factors. We have developed such a system to study mammalian trans-acting factors that regulate the transcription of class II major histocompatibility complex genes, using the mutant cell lines RM2 and RM3. These cells, derived from the human B-cell line Raji, specifically fail to transcribe their class II major histocompatibility complex genes. Here we show that a transfected HLA-DR alpha class II major histocompatibility complex gene, like the endogenous HLA-DR alpha genes, is efficiently transcribed in Raji cells but not in RM2 or RM3 cells, demonstrating that the mutant cells are deficient in a specific trans-acting factor required for transcription of these genes. HLA-DR expression in RM2 and RM3 cells is rescued by fusion to another B-cell line but not by fusion to each other. Thus, the defects in the two cell lines are recessive and noncomplementing and define a locus whose wild-type product we designate TF-X1. We show that TF-X1 influences the activity of a 24-base-pair B-cell-specific cis-acting transcription element in the HLA-DR alpha promoter. However, in three different biochemical assays, we detect no difference between wild-type and mutant cells in the DNA-binding proteins that interact with these DNA sequences. Thus, the defective version of TF-X1 may be a DNA-binding protein that binds to the HLA-DR alpha promoter but fails to activate transcription. Alternatively, TF-X1 may not be a DNA-binding protein at all. Images PMID:3143110

  8. Analysis of global O(t(-α)) stability and global asymptotical periodicity for a class of fractional-order complex-valued neural networks with time varying delays.

    PubMed

    Rakkiyappan, R; Sivaranjani, R; Velmurugan, G; Cao, Jinde

    2016-05-01

    In this paper, the problem of the global O(t(-α)) stability and global asymptotic periodicity for a class of fractional-order complex-valued neural networks (FCVNNs) with time varying delays is investigated. By constructing suitable Lyapunov functionals and a Leibniz rule for fractional differentiation, some new sufficient conditions are established to ensure that the addressed FCVNNs are globally O(t(-α)) stable. Moreover, some sufficient conditions for the global asymptotic periodicity of the addressed FCVNNs with time varying delays are derived, showing that all solutions converge to the same periodic function. Finally, numerical examples are given to demonstrate the effectiveness and usefulness of our theoretical results. PMID:26922720

  9. Acute Viral Escape Selectively Impairs Nef-Mediated Major Histocompatibility Complex Class I Downmodulation and Increases Susceptibility to Antiviral T Cells

    PubMed Central

    Weiler, Andrea M.; Das, Arpita; Akinyosoye, Oluwasayo; Cui, Sherry; O'Connor, Shelby L.; Scheef, Elizabeth A.; Reed, Jason S.; Panganiban, Antonito T.; Sacha, Jonah B.; Rakasz, Eva G.; Friedrich, Thomas C.

    2015-01-01

    Nef-specific CD8+ T lymphocytes (CD8TL) are associated with control of simian immunodeficiency virus (SIV) despite extensive nef variation between and within animals. Deep viral sequencing of the immunodominant Mamu-B*017:01-restricted Nef165–173IW9 epitope revealed highly restricted evolution. A common acute escape variant, T170I, unexpectedly and uniquely degraded Nef's major histocompatibility complex class I (MHC-I) downregulatory capacity, rendering the virus more vulnerable to CD8TL targeting other epitopes. These data aid in a mechanistic understanding of Nef functions and suggest means of immunity-mediated control of lentivirus replication. PMID:26637459

  10. Acute Viral Escape Selectively Impairs Nef-Mediated Major Histocompatibility Complex Class I Downmodulation and Increases Susceptibility to Antiviral T Cells.

    PubMed

    Weiler, Andrea M; Das, Arpita; Akinyosoye, Oluwasayo; Cui, Sherry; O'Connor, Shelby L; Scheef, Elizabeth A; Reed, Jason S; Panganiban, Antonito T; Sacha, Jonah B; Rakasz, Eva G; Friedrich, Thomas C; Maness, Nicholas J

    2016-02-01

    Nef-specific CD8(+) T lymphocytes (CD8TL) are associated with control of simian immunodeficiency virus (SIV) despite extensive nef variation between and within animals. Deep viral sequencing of the immunodominant Mamu-B*017:01-restricted Nef165-173IW9 epitope revealed highly restricted evolution. A common acute escape variant, T170I, unexpectedly and uniquely degraded Nef's major histocompatibility complex class I (MHC-I) downregulatory capacity, rendering the virus more vulnerable to CD8TL targeting other epitopes. These data aid in a mechanistic understanding of Nef functions and suggest means of immunity-mediated control of lentivirus replication. PMID:26637459

  11. A PTIP-PA1 subcomplex promotes transcription for IgH class switching independently from the associated MLL3/MLL4 methyltransferase complex.

    PubMed

    Starnes, Linda M; Su, Dan; Pikkupeura, Laura M; Weinert, Brian T; Santos, Margarida A; Mund, Andreas; Soria, Rebeca; Cho, Young-Wook; Pozdnyakova, Irina; Kubec Højfeldt, Martina; Vala, Andrea; Yang, Wenjing; López-Méndez, Blanca; Lee, Ji-Eun; Peng, Weiqun; Yuan, Joan; Ge, Kai; Montoya, Guillermo; Nussenzweig, André; Choudhary, Chunaram; Daniel, Jeremy A

    2016-01-15

    Class switch recombination (CSR) diversifies antibodies for productive immune responses while maintaining stability of the B-cell genome. Transcription at the immunoglobulin heavy chain (Igh) locus targets CSR-associated DNA damage and is promoted by the BRCT domain-containing PTIP (Pax transactivation domain-interacting protein). Although PTIP is a unique component of the mixed-lineage leukemia 3 (MLL3)/MLL4 chromatin-modifying complex, the mechanisms for how PTIP promotes transcription remain unclear. Here we dissected the minimal structural requirements of PTIP and its different protein complexes using quantitative proteomics in primary lymphocytes. We found that PTIP functions in transcription and CSR separately from its association with the MLL3/MLL4 complex and from its localization to sites of DNA damage. We identified a tandem BRCT domain of PTIP that is sufficient for CSR and identified PA1 as its main functional protein partner. Collectively, we provide genetic and biochemical evidence that a PTIP-PA1 subcomplex functions independently from the MLL3/MLL4 complex to mediate transcription during CSR. These results further our understanding of how multifunctional chromatin-modifying complexes are organized by subcomplexes that harbor unique and distinct activities. PMID:26744420

  12. A PTIP–PA1 subcomplex promotes transcription for IgH class switching independently from the associated MLL3/MLL4 methyltransferase complex

    PubMed Central

    Starnes, Linda M.; Su, Dan; Pikkupeura, Laura M.; Weinert, Brian T.; Santos, Margarida A.; Mund, Andreas; Soria, Rebeca; Cho, Young-Wook; Pozdnyakova, Irina; Kubec Højfeldt, Martina; Vala, Andrea; Yang, Wenjing; López-Méndez, Blanca; Lee, Ji-Eun; Peng, Weiqun; Yuan, Joan; Ge, Kai; Montoya, Guillermo; Nussenzweig, André; Choudhary, Chunaram; Daniel, Jeremy A.

    2016-01-01

    Class switch recombination (CSR) diversifies antibodies for productive immune responses while maintaining stability of the B-cell genome. Transcription at the immunoglobulin heavy chain (Igh) locus targets CSR-associated DNA damage and is promoted by the BRCT domain-containing PTIP (Pax transactivation domain-interacting protein). Although PTIP is a unique component of the mixed-lineage leukemia 3 (MLL3)/MLL4 chromatin-modifying complex, the mechanisms for how PTIP promotes transcription remain unclear. Here we dissected the minimal structural requirements of PTIP and its different protein complexes using quantitative proteomics in primary lymphocytes. We found that PTIP functions in transcription and CSR separately from its association with the MLL3/MLL4 complex and from its localization to sites of DNA damage. We identified a tandem BRCT domain of PTIP that is sufficient for CSR and identified PA1 as its main functional protein partner. Collectively, we provide genetic and biochemical evidence that a PTIP–PA1 subcomplex functions independently from the MLL3/MLL4 complex to mediate transcription during CSR. These results further our understanding of how multifunctional chromatin-modifying complexes are organized by subcomplexes that harbor unique and distinct activities. PMID:26744420

  13. A new class of luminescent Cu(I) complexes with tripodal ligands – TADF emitters for the yellow to red color range.

    PubMed

    Gneuß, Timo; Leitl, Markus J; Finger, Lars H; Rau, Nicholas; Yersin, Hartmut; Sundermeyer, Jörg

    2015-05-14

    A new class of emissive and neutral Cu(I) compounds with tripodal ligands is presented. The complexes were characterized chemically, computationally, and photophysically. Under ambient conditions, the powders of the compounds exhibit yellow to red emission with quantum yields ranging from about 5% to 35%. The emission represents a thermally activated delayed fluorescence (TADF) combined with a short-lived phosphorescence which represents a rare situation and is a consequence of high spin-orbit coupling (SOC). In the series of the investigated compounds the non-radiative rates increase with decreasing emission energy according to the energy gap law while the radiative rate is almost constant. Furthermore, a well-fit linear dependence between the experimental emission energies and the transition energies calculated by DFT and TD-DFT methods could be established, thus supporting the applicability of these computational methods also to Cu(I) complexes. PMID:25434594

  14. Versatility of using major histocompatibility complex class II dextramers for derivation and characterization of antigen-specific, autoreactive T cell hybridomas.

    PubMed

    Krishnan, Bharathi; Massilamany, Chandirasegaran; Basavalingappa, Rakesh H; Rajasekaran, Rajkumar A; Kuszynski, Charles; Switzer, Barbara; Peterson, Daniel A; Reddy, Jay

    2015-11-01

    Antigen-specific, T cell hybridomas are useful to study the cellular, molecular and functional events, but their generation is a lengthy process. Thus, there is a need to develop robust methods to generate the hybridoma clones rapidly in a short period of time. To this end, we have demonstrated a novel approach using major histocompatibility complex (MHC) class II dextramers to generate T cell hybridomas for an autoantigen, proteolipid protein (PLP) 139-151. Using MHC class II dextramers assembled with PLP 139-151 as screening and sorting tools, we successfully obtained mono antigen-specific clones within seven to eight weeks. In conjunction with other T cell markers, dextramers permitted phenotypic characterization of hybridoma clones for their antigen specificity in a single step by flow cytometry. Importantly, we achieved successful fusions using dextramer(+) cells sorted by flow cytometry as a starting population, resulting in direct identification of multiple antigen-specific clones. Characterization of selected clones led us to identify chemokine receptor, CCR4(+) to be expressed consistently, but their cytokine-producing ability was variable. Our work provides a proof-of principle that the antigen-specific, CD4 T cell hybridoma clones can be generated directly using MHC class II dextramers. The availability of hybridoma clones that bind dextramers may serve as useful tools for various in vitro and in vivo applications. PMID:26268454

  15. Introduction of protein or DNA delivered via recombinant Salmonella typhimurium into the major histocompatibility complex class I presentation pathway of macrophages.

    PubMed

    Catic, A; Dietrich, G; Gentschev, I; Goebel, W; Kaufmann, S H; Hess, J

    1999-02-01

    Recombinant (r) Salmonella typhimurium aroA strains which display the hen egg ovalbumin OVA(257-264) peptide SIINFEKL in secreted form were constructed. In addition, attenuated rS. typhimurium pcDNA-OVA constructs harbouring a eukaryotic expression plasmid encoding complete OVA were used to introduce the immunodominant OVA(257-264) epitope into the major histocompatibility complex (MHC) class I presentation pathway. Both modes of antigen delivery (DNA and protein) by Salmonella vaccine carriers stimulated OVA(257-264)-specific CD8 T-cell hybridomas. An in vitro infection system was established that allowed both rSalmonella carrier devices to facilitate MHC class I delivery of OVA(257-264) by coexpression of listeriolysin (Hly) or by coinfection with rS. typhimurium Hlys (Hess J., Gentschev I., Miko D., Welzel M., Ladel C., Goebel W., Kaufmann S.H.E., Proc. Natl. Acad. Sci. USA 93 (1996) 1458-1463). Coexpression of Hly and coinfection with rS. typhimurium Hlys slightly improved MHC class I processing of OVA. Our data provide further evidence for the feasibility of attenuated, Hly-expressing rS. typhimurium carriers secreting heterologous antigens or harbouring heterologous DNA as effective vaccines for stimulating CD8 T cells in addition to CD4 T cells. PMID:10594975

  16. Tissue factor initiates glomerular fibrin deposition and promotes major histocompatibility complex class II expression in crescentic glomerulonephritis.

    PubMed Central

    Erlich, J. H.; Holdsworth, S. R.; Tipping, P. G.

    1997-01-01

    Increased glomerular tissue factor (TF) expression is associated with glomerular fibrin deposition and renal failure in human and experimental crescentic glomerulonephritis (GN). However, the in vivo functional contribution of TF to the development of glomerular fibrin deposition, crescent formation, and renal failure in GN has not been established. The contribution of TF to fibrin deposition and renal injury was studied in a rabbit model of crescentic GN in which glomerular macrophage infiltration, augmented TF expression, and fibrin deposition are prominent. Administration of anti-TF antibody inhibited glomerular TF activity in nephritic glomeruli by 96%, without affecting macrophage accumulation or systemic indices of coagulation. Anti-TF antibody significantly reduced glomerular fibrin deposition (fibrin scores, 0.43 +/- 0.10 (treated) and 1.40 +/- 0.19 (control); P < 0.0005), crescent formation (0.33 +/- 0.05 (treated) and 1.0 +/- 0.06 (control); P < 0.0005), and development of renal failure (serum creatinine, 168 +/- 22 mumol/l (treated) and 267 +/- 35 mumol/l (control); P < 0.04). This was associated with significant reduction in proteinuria (1189 +/- 277 mg/24 hours (treated) and 2060 +/- 336 mg/24 hours (control); P < 0.03) and expression of MHC class II antigen in glomeruli (1.25 +/- 0.41 (treated) and 2.83 +/- 0.53 (control); P < 0.03) and in tubules and interstitial areas. These data demonstrate that TF is the major in vivo initiator of fibrin deposition in crescentic GN. The reduction in proteinuria and glomerular major histocompatibility class II antigen expression by TF inhibition suggests that TF may also activate other mediators that contribute to glomerular injury. Images Figure 1 PMID:9060825

  17. Strategic mutations in the class I major histocompatibility complex HLA-A2 independently affect both peptide binding and T cell receptor recognition.

    PubMed

    Baxter, Tiffany K; Gagnon, Susan J; Davis-Harrison, Rebecca L; Beck, John C; Binz, Anne-Kathrin; Turner, Richard V; Biddison, William E; Baker, Brian M

    2004-07-01

    Mutational studies of T cell receptor (TCR) contact residues on the surface of the human class I major histocompatibility complex (MHC) molecule HLA-A2 have identified a "functional hot spot" that comprises Arg(65) and Lys(66) and is involved in recognition by most peptide-specific HLA-A2-restricted TCRs. Although there is a significant amount of functional data on the effects of mutations at these positions, there is comparatively little biochemical information that could illuminate their mode of action. Here, we have used a combination of fluorescence anisotropy, functional assays, and Biacore binding experiments to examine the effects of mutations at these positions on the peptide-MHC interaction and TCR recognition. The results indicate that mutations at both position 65 and position 66 influence peptide binding by HLA-A2 to various extents. In particular, mutations at position 66 result in significantly increased peptide dissociation rates. However, these effects are independent of their effects on TCR recognition, and the Arg(65)-Lys(66) region thus represents a true "hot spot" for TCR recognition. We also made the observation that in vitro T cell reactivity does not scale with the half-life of the peptide-MHC complex, as is often assumed. Finally, position 66 is implicated in the "dual recognition" of both peptide and TCR, emphasizing the multiple roles of the class I MHC peptide-binding domain. PMID:15131131

  18. Molecular and biological interaction between major histocompatibility complex class I antigens and luteinizing hormone receptors or beta-adrenergic receptors triggers cellular response in mice.

    PubMed Central

    Solano, A R; Cremaschi, G; Sánchez, M L; Borda, E; Sterin-Borda, L; Podestá, E J

    1988-01-01

    Purified IgG from BALB/c mouse anti-C3H serum exerts positive inotropic and chronotropic effects in C3H mouse atria and induces testosterone synthesis in C3H mouse Leydig cells. The effect depends on IgG concentration and can be abolished by beta-adrenergic-receptor and luteinizing hormone-receptor antagonists. IgG interferes with the binding of dihydroalprenolol and luteinizing hormone. Monoclonal antibodies against major histocompatibility complex class I antigens were active on the Leydig cells of C3H and BALB/c mice. There was a parallelism between the effect of each individual monoclonal antibody with specificity for a particular haplotype and the response of the target cell from the strains carrying such haplotypes. These antibodies could precipitate the soluble luteinizing hormone-receptor complex. The results suggested that bound hormone triggers the association of major histocompatibility class I antigen with the receptor, thereby activating the respective target cells. PMID:2839829

  19. New class of oxotechnetium (5+) chelate complexes containing a TcON/sub 2/S/sub 2/ core

    SciTech Connect

    Davison, A.; Jones, A. G.; Orvig, C.; Sohn, M.

    1981-06-01

    The benzoyl-protected dimercaptodiamides (PhCOS(CH/sub 2/)/sub n/CONH)/sub 2/X (n = 1, X = (CH/sub 2/)/sub 2/, (CH/sub 2/)/sub 3/, and 0-C/sub 6/H/sub 4/; n = 2, X = (CH/sub 2/)/sub 2/ and (CH/sub 2/)/sub 3/) have been synthesized. From these, via the sodium dithionite reduction of TcO/sub 4//sup -/ in base, the technetium complexes (TcO(S(CH/sub 2/)/sub n/CONXNCO(CH/sub 2/)/sub n/S))/sup -/ (n = 1, X = (CH/sub 2/)/sub 2/, (CH/sub 2/)/sub 3/, and o-C/sub 6/H/sub 4/; n = 2, X = (CH/sub 2/)/sub 2/) have been prepared. The synthesis and characterization of the complexes, and their precursors, are presented, and the radiopharmaceutical applicability is discussed.

  20. On conjugate gradient type methods and polynomial preconditioners for a class of complex non-Hermitian matrices

    NASA Technical Reports Server (NTRS)

    Freund, Roland

    1988-01-01

    Conjugate gradient type methods are considered for the solution of large linear systems Ax = b with complex coefficient matrices of the type A = T + i(sigma)I where T is Hermitian and sigma, a real scalar. Three different conjugate gradient type approaches with iterates defined by a minimal residual property, a Galerkin type condition, and an Euclidian error minimization, respectively, are investigated. In particular, numerically stable implementations based on the ideas behind Paige and Saunder's SYMMLQ and MINRES for real symmetric matrices are proposed. Error bounds for all three methods are derived. It is shown how the special shift structure of A can be preserved by using polynomial preconditioning. Results on the optimal choice of the polynomial preconditioner are given. Also, some numerical experiments for matrices arising from finite difference approximations to the complex Helmholtz equation are reported.

  1. Copper(I) Complexes of Zwitterionic Imidazolium-2-Amidinates, a Promising Class of Electroneutral, Amidinate-Type Ligands.

    PubMed

    Márquez, Astrid; Ávila, Elena; Urbaneja, Carmen; Álvarez, Eleuterio; Palma, Pilar; Cámpora, Juan

    2015-11-16

    The first complexes containing imidazolium-2-amidinates as ligands (betaine-type adducts of imidazolium-based carbenes and carbodiimides, NHC-CDI) are reported. Interaction of the sterically hindered betaines ICyCDI(DiPP) and IMeCDI(DiPP) [both bearing 2,6-diisopropylphenyl (DiPP) substituents on the terminal N atoms] with Cu(I) acetate affords mononuclear, electroneutral complexes 1a and 1b, which contain NHC-CDI and acetate ligands terminally bound to linear Cu(I) centers. In contrast, the less encumbered ligand ICyCDI(p-Tol), with p-tolyl substituents on the nitrogen donor atoms, affords a dicationic trigonal paddlewheel complex, [Cu2(μ-ICyCDI(p-Tol))3](2+)[OAc(-)]2 (2-OAc). The nuclear magnetic resonance (NMR) resonances of this compound are broad and indicate that in solution the acetate anion and the betaine ligands compete for binding the Cu atom. Replacing the external acetate with the less coordinating tetraphenylborate anion provides the corresponding derivative 2-BPh4 that, in contrast with 2-OAc, gives rise to sharp and well-defined NMR spectra. The short Cu-Cu distance in the binuclear dication [Cu2(μ-ICyCDI(p-Tol))3](2+) observed in the X-ray structures of 2-BPh4 and 2-OAc, ca. 2.42 Å, points to a relatively strong "cuprophilic" interaction. Attempts to force the bridging coordination mode of IMeCDI(DiPP) displacing the acetate anion with BPh4(-) led to the isolation of the cationic mononuclear derivative [Cu(IMeCDI(DiPP))2](+)[BPh4](-) (3b) that contains two terminally bound betaine ligands. Compound 3b readily decomposes upon being heated, cleanly affording the bis-carbene complex [Cu(IMe)2](+)[BPh4(-)] (4) and releasing the corresponding carbodiimide (C(═N-DiPP)2). PMID:26517572

  2. You Can't Get There From Here! Problems and Potential Solutions in Developing New Classes of Complex Systems

    NASA Technical Reports Server (NTRS)

    Hinchey, Michael G.; Rash, James L.; Truszkowski, Walter F.; Rouff, Christopher A.; Sterritt, Roy

    2005-01-01

    The explosion of capabilities and new products within the sphere of Information Technology (IT) has fostered widespread, overly optimistic opinions regarding the industry, based on common but unjustified assumptions of quality and correctness of software. These assumptions are encouraged by software producers and vendors, who at this late date have not succeeded in finding a way to overcome the lack of an automated, mathematically sound way to develop correct systems from requirements. NASA faces this dilemma as it envisages advanced mission concepts that involve large swarms of small spacecraft that will engage cooperatively to acheve science goals. Such missions entail levels of complexity that beg for new methods for system development far beyond today's methods, which are inadequate for ensuring correct behavior of large numbers of interacting intelligent mission elements. New system development techniques recently devised through NASA-led research will offer some innovative approaches to achieving correctness in complex system development, including autonomous swarm missions that exhibit emergent behavior, as well as general software products created by the computing industry.

  3. Dialkyldiselenophosphinato-metal complexes - a new class of single source precursors for deposition of metal selenide thin films and nanoparticles

    NASA Astrophysics Data System (ADS)

    Malik, Sajid N.; Akhtar, Masood; Revaprasadu, Neerish; Qadeer Malik, Abdul; Azad Malik, Mohammad

    2014-08-01

    We report here a new synthetic approach for convenient and high yield synthesis of dialkyldiselenophosphinato-metal complexes. A number of diphenyldiselenophosphinato-metal as well as diisopropyldiselenophosphinato-metal complexes have been synthesized and used as precursors for deposition of semiconductor thin films and nanoparticles. Cubic Cu2-xSe and tetragonal CuInSe2 thin films have been deposited by AACVD at 400, 450 and 500 °C whereas cubic PbSe and tetragonal CZTSe thin films have been deposited through doctor blade method followed by annealing. SEM investigations revealed significant differences in morphology of the films deposited at different temperatures. Preparation of Cu2-xSe and In2Se3 nanoparticles using diisopropyldiselenophosphinato-metal precursors has been carried out by colloidal method in HDA/TOP system. Cu2-xSe nanoparticles (grown at 250 °C) and In2Se3 nanoparticles (grown at 270 °C) have a mean diameter of 5.0 ± 1.2 nm and 13 ± 2.5 nm, respectively.

  4. Characterization and evolution of major histocompatibility complex class II genes in the aye-aye, Daubentonia madagascariensis.

    PubMed

    Go, Yasuhiro; Rakotoarisoa, Gilbert; Kawamoto, Yoshi; Shima, Taizo; Koyama, Naoki; Randrianjafy, Albert; Mora, Roger; Hirai, Hirohisa

    2005-04-01

    Major histocompatibility complex genes (Mhc-DQB and Mhc-DRB) were sequenced in seven aye-ayes (Daubentonia madagascariecsis), which is an endemic and endangered species in Madagascar. An aye-aye from a north-eastern population showed genetic relatedness to individuals of a north-western population and had a somewhat different repertoire from another north-eastern individual. These observations suggest that the extent of genetic variation in Mhc genes is not excessively small in the aye-aye in spite of recent rapid destruction of their habitat by human activities. In light of Mhc gene evolution, trans-species and allelic polymorphisms can be estimated to have been retained for more than 50 Ma (million years) based on the time scale of lemur evolution. PMID:15322927

  5. Novel class of Bi(iii) hydroxamato complexes: synthesis, urease inhibitory activity and activity against H. pylori.

    PubMed

    Keogan, D M; Twamley, B; Fitzgerald-Hughes, D; Griffith, D M

    2016-07-01

    Reaction of Bi(NO3)3 with benzohydroxamic acid (Bha) and salicylhydroxamic acid (Sha) gives the novel Bi(iii) complexes [Bi2(Bha-1H)2(μ-Bha-1H)2(η(2)-NO3)2] () and [Bi6(CH3OH)2(η(1)-NO3)2(η(2)-NO3)(OH2)2(Sha-1H)12](NO3)2 (). X-ray crystal structure of reveals two hydroxamato coordination modes; bidentate bridging (O, O') and bidentate non-bridging (O, O') and of reveals one coordination mode; bidentate bridging (O, O'). , specifically designed to and demonstrated to inhibit the activity of urease, exhibits excellent antibacterial activity against three strains of Helicobacter pylori with MIC ≥ 16 μg mL(-1). PMID:27314129

  6. Complex, multiple ore fluids in the world class southeast Missouri Pb-Zn-Cu MVT deposits: Sulfur isotope evidence

    SciTech Connect

    Burstein, I.B.; Shelton, K.L. ); Gregg, J.M.; Hagni, R.D. . Dept. of Geology Geophysics)

    1993-03-01

    More than 625 sulfur isotope data from all of the mines in the Viburnum Trend Pb-Zn-Cu MVT district of southeast Missouri have identified large temporal variations of sulfur isotope composition within the complex mineral paragenesis of each mine as well as large spatial variations in sulfur isotope composition within and among mines. The general trend of [delta][sup 34]S values with increasing paragenetic time is: Early pyrite, [minus]9 to [minus]1[per thousand]; Early bornite-chalcopyrite, [minus]9 to +16[per thousand]; Massive chalcopyrite, [minus]14 to +9[per thousand]; Main sphalerite, +12 to +26[per thousand]; Cuboctahedral galena, +5 to +22[per thousand]; Main marcasite, [minus]19 to +9[per thousand]; Cubic galena, [minus]2 to +13[per thousand] Late sphalerite, +6 to +13[per thousand]; Late marcasite, +10 to +19[per thousand]; Late chalcopyrite, +2 to +33[per thousand]. Spatial correlation of [delta][sup 34]S values of the Main stages of sulfide mineralization in the West Fork mine may indicate that the cuboctahedral galena in this mine was precipitated from a Pb-rich, S-poor fluid that incorporated sulfur from reaction with earlier marcasite. In the rest of the district, ore precipitation may have occurred by mixing of Pb-rich, S-poor fluids with Pb-poor, S-rich fluids. Complex mineral parageneses and sulfur isotope systematics within the southeast Missouri Pb-Zn-Cu MVT deposits are compatible with multiple, metal-specific fluids and multiple precipitation mechanisms, as well as multiple sulfur sources.

  7. Guanidinium-Rich, Glycerol-Derived Oligocarbonates: A New Class of Cell-Penetrating Molecular Transporters That Complex, Deliver, and Release siRNA

    PubMed Central

    Wender, Paul A.; Huttner, Melanie A.; Staveness, Daryl; Vargas, Jessica R.; Xu, Adele F.

    2015-01-01

    A highly versatile and step-economical route to a new class of guanidinium-rich molecular transporters and evaluation of their ability to complex, deliver, and release siRNA are described. These new drug/probe delivery systems are prepared in only two steps, irrespective of length or composition, using an organocatalytic ring-opening co-oligomerization of glycerol-derived cyclic carbonate monomers incorporating either protected guanidine or lipid side chains. The resultant amphipathic co-oligomers are highly effective vehicles for siRNA delivery, providing an excellent level of target protein suppression (>85%). These new oligocarbonates are nontoxic at levels required for cell penetration and can be tuned for particle size. Relative to the previously reported methyl(trimethylene)carbonate (MTC) scaffold, the ether linkage at C2 in the new transporters markedly enhances the stability of the siRNA/co-oligomer complexes. Both hybrid co-oligomers, containing a mixture of glycerol- and MTC-derived monomers, and co-oligomers containing only glycerol monomers are found to provide tunable control over siRNA complex stability. On the basis of a glycerol and CO2 backbone, these new co-oligomers represent a rapidly tunable and biocompatible siRNA delivery system that is highly effective in suppressing target protein synthesis. PMID:25588140

  8. Guanidinium-rich, glycerol-derived oligocarbonates: a new class of cell-penetrating molecular transporters that complex, deliver, and release siRNA.

    PubMed

    Wender, Paul A; Huttner, Melanie A; Staveness, Daryl; Vargas, Jessica R; Xu, Adele F

    2015-03-01

    A highly versatile and step-economical route to a new class of guanidinium-rich molecular transporters and evaluation of their ability to complex, deliver, and release siRNA are described. These new drug/probe delivery systems are prepared in only two steps, irrespective of length or composition, using an organocatalytic ring-opening co-oligomerization of glycerol-derived cyclic carbonate monomers incorporating either protected guanidine or lipid side chains. The resultant amphipathic co-oligomers are highly effective vehicles for siRNA delivery, providing an excellent level of target protein suppression (>85%). These new oligocarbonates are nontoxic at levels required for cell penetration and can be tuned for particle size. Relative to the previously reported methyl(trimethylene)carbonate (MTC) scaffold, the ether linkage at C2 in the new transporters markedly enhances the stability of the siRNA/co-oligomer complexes. Both hybrid co-oligomers, containing a mixture of glycerol- and MTC-derived monomers, and co-oligomers containing only glycerol monomers are found to provide tunable control over siRNA complex stability. On the basis of a glycerol and CO2 backbone, these new co-oligomers represent a rapidly tunable and biocompatible siRNA delivery system that is highly effective in suppressing target protein synthesis. PMID:25588140

  9. The PI3K class III complex promotes axon pruning by downregulating a Ptc-derived signal via endosome-lysosomal degradation.

    PubMed

    Issman-Zecharya, Noa; Schuldiner, Oren

    2014-11-24

    Developmental axon pruning is essential for wiring the mature nervous system, but its regulation remains poorly understood. Here we show that the endosomal-lysosomal pathway regulates developmental pruning of Drosophila mushroom body γ neurons. We demonstrate that the UV radiation resistance-associated gene (UVRAG) functions together with all core components of the phosphatidylinositol 3-kinase class III (PI3K-cIII) complex to promote pruning via the endocytic pathway. By studying several PI(3)P binding proteins, we found that Hrs, a subunit of the ESCRT-0 complex, required for multivesicular body (MVB) maturation, is essential for normal pruning progression. Thus, we hypothesized the existence of an inhibitory signal that needs to be downregulated. Finally, our data suggest that the Hedgehog receptor, Patched, is the source of this inhibitory signal likely functioning in a Smo-independent manner. Taken together, our in vivo study demonstrates that the PI3K-cIII complex is essential for downregulating Patched via the endosomal-lysosomal pathway to execute axon pruning. PMID:25458013

  10. TCR-like antibodies distinguish conformational and functional differences in two- versus four-domain auto reactive MHC class II-peptide complexes.

    PubMed

    Dahan, Rony; Tabul, Moran; Chou, Yuan K; Meza-Romero, Roberto; Andrew, Shayne; Ferro, Adolph J; Burrows, Gregory G; Offner, Halina; Vandenbark, Arthur A; Reiter, Yoram

    2011-05-01

    Antigen-presenting cell-associated four-domain MHC class II (MHC-II) molecules play a central role in activating autoreactive CD4(+) T cells involved in multiple sclerosis (MS) and type 1 diabetes (T1D). In contrast, two-domain MHC-II structures with the same covalently attached self-peptide (recombinant T-cell receptor ligands (RTLs)) can regulate pathogenic CD4(+) T cells and reverse clinical signs of experimental autoimmune diseases. RTL1000, which is composed of the β1α1 domains of human leukocyte antigen (HLA)-DR2 linked to the encephalitogenic human myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide, was recently shown to be safe and well tolerated in a phase I clinical trial in MS. To evaluate the opposing biological effects of four- versus two-domain MHC-II structures, we screened phage Fab antibodies (Abs) for the neutralizing activity of RTL1000. Five different TCR-like Abs were identified that could distinguish between the two- versus four-domain MHC-peptide complexes while the cognate TCR was unable to make such a distinction. Moreover, Fab detection of native two-domain HLA-DR structures in human plasma implies that there are naturally occurring regulatory MHC-peptide complexes. These results demonstrate for the first time distinct conformational determinants characteristic of activating versus tolerogenic MHC-peptide complexes involved in human autoimmunity. PMID:21469129

  11. Association between Single Nucleotide Polymorphisms of the Major Histocompatibility Complex Class II Gene and Newcastle Disease Virus Titre and Body Weight in Leung Hang Khao Chickens

    PubMed Central

    Molee, A.; Kongroi, K.; Kuadsantia, P.; Poompramun, C.; Likitdecharote, B.

    2016-01-01

    The aim of the present study was to investigate the effect of single nucleotide polymorphisms in the major histocompatibility complex (MHC) class II gene on resistance to Newcastle disease virus and body weight of the Thai indigenous chicken, Leung Hang Khao (Gallus gallus domesticus). Blood samples were collected for single nucleotide polymorphism analysis from 485 chickens. Polymerase chain reaction sequencing was used to classify single nucleotide polymorphisms of class II MHC. Body weights were measured at the ages of 3, 4, 5, and 7 months. Titres of Newcastle disease virus at 2 weeks to 7 months were determined and the correlation between body weight and titre was analysed. The association between single nucleotide polymorphisms and body weight and titre were analysed by a generalized linear model. Seven single nucleotide polymorphisms were identified: C125T, A126T, C209G, C242T, A243T, C244T, and A254T. Significant correlations between log titre and body weight were found at 2 and 4 weeks. Associations between single nucleotide polymorphisms and titre were found for C209G and A254T, and between all single nucleotide polymorphisms (except A243T) and body weight. The results showed that class II MHC is associated with both titre of Newcastle disease virus and body weight in Leung Hang Khao chickens. This is of concern because improved growth traits are the main goal of breeding selection. Moreover, the results suggested that MHC has a pleiotropic effect on the titre and growth performance. This mechanism should be investigated in a future study. PMID:26732325

  12. SU-8/Pyrex microchip electrophoresis with integrated electrochemical detection for class-selective electrochemical index determination of phenolic compounds in complex samples.

    PubMed

    Castañeda, Raquel; Vilela, Diana; González, María Cristina; Mendoza, Sandra; Escarpa, Alberto

    2013-07-01

    A SU-8/Pyrex single-channel microchip integrating three 100 μm Pt electrodes (MCE-ED) for class-selective electrochemical index determination (CSEID) of phenolic acids and flavonoids in complex extracts of Tagetes lucida (Tl), Mentha piperita (Mp), Cymbopogon citratus (Cc), Calendula officinalis (Co), and Cynara scolymus (Cs) is proposed. Under strategic conditions controlled by a MES buffer (pH 5.0; 25 mM) and accordingly to the antioxidant acid-base properties, the simultaneous measurement of total acids and flavonoids indexes was achieved in less than 100 s with excellent analytical performance. The reliability of MCE-ED approach was demonstrated toward the high agreement between the total phenolic content obtained using microchip approach with those obtained by the well-established HPLC-DAD; revealing both identical order regarding the total phenolic content in the target samples. In addition, further comparison of MCE-ED with the traditional Folin-Ciocalteu antioxidant capacity assay, showed that MCE-ED approach could become a class-selective antioxidant capacity assay revealing that the sample antioxidant capacity was decreasing as Tl > Mp > Cs > Cc > Co according to their endogenous polyphenol content. These results suggested that the microchip approach is not only a reliable method for fast assessment of class-selective antioxidants constituting a very good alternative to the long analysis times and the using of toxic solvents required in HPLC but a novel truly antioxidant capacity assay. This excellent analytical performance is connected with the key-features of the "ready-to-use" system employed in this work such as portability, full integration of electrochemical detection, easy-operation, and potential MCE-ED disposability. PMID:23595251

  13. Closely Related Mycobacterial Strains Demonstrate Contrasting Levels of Efficacy as Antitumor Vaccines and Are Processed for Major Histocompatibility Complex Class I Presentation by Multiple Routes in Dendritic Cells

    PubMed Central

    Cheadle, Eleanor J.; O'Donnell, Dearbhaile; Selby, Peter J.; Jackson, Andrew M.

    2005-01-01

    Mycobacteria expressing recombinant antigens are already being developed as vaccines against both infections and tumors. Little is known about how dendritic cells might process such antigens. Two different mycobacterial species, the fast-growing Mycobacterium smegmatis and the slow-growing M. bovis M. bovis BCG, were engineered to express a model tumor antigen, the Kb-restricted dominant cytotoxic T-lymphocyte epitope OVA257-264. Recombinant M. bovis BCG but not recombinant M. smegmatis conferred protection to mice challenged with the B16-OVA tumor cell line. We went on to investigate whether the contrast in antitumor efficacy could be due to differences in how dendritic cells process antigen from the two mycobacterial strains for class I presentation. Both strains of mycobacteria caused phenotypic maturation of dendritic cells, but recombinant M. smegmatis infection led to a greater degree of dendritic cell maturation than recombinant M. bovis BCG infection. Antigen from recombinant M. smegmatis was processed and presented as OVA257-264 on Kb molecules by the dendritic cell line DC2.4 but not by bone marrow-derived dendritic cells (BMDC) or splenic dendritic cells. In contrast, antigen from recombinant M. bovis BCG was presented by all three dendritic cell types as long as the mycobacteria were viable. Such presentation was dependent on proteasome function and nascent major histocompatibility complex (MHC) class I molecules in DC2.4 cells but independent of the proteasome and transporter associated with antigen processings (TAP) in BMDC and splenic dendritic cells. These data demonstrate for the first time that antigen vectored by the slow-growing M. bovis BCG but not that vectored by fast-growing, readily destroyed M. smegmatis is processed and presented on MHC class I by in vitro-generated dendritic cells, which has implications for recombinant microbial vaccine development. PMID:15664917

  14. Construction of Soluble Mamu-B*1703, a Class I Major Histocompatibility Complex of Chinese Rhesus Macaques, Monomer and Tetramer Loaded with a Simian Immunodeficiency Virus Peptide

    PubMed Central

    Ouyang, Dongyun; Wang, Xiaoying; He, Xianhui; Xu, Lihui; Shi, Huanjing; Gao, Qi; Guo, He

    2009-01-01

    Chinese-descent rhesus macaques have become more prevalent for HIV infection and vaccine investigation than Indian-origin macaques. Most of the currently available data and reagents such as major histocompatibility complex (MHC) class I tetramers, however, were derived from Indian-origin macaques due to the dominant use of these animals in history. Although there are significant differences in the immunogenetic background between the two macaque populations, they share a few of common MHC class I alleles. We reported in this study the procedure for preparation of a soluble Mamu-B*1703 (a MHC class I molecule of Chinese macaques) monomer and tetramer loaded with a dominant simian immunodeficiency virus (SIV) epitope IW9 (IRYPKTFGW) that was identified to be Mamu-B*1701-restricted in Indian macaques. The DNA fragment encoding the Mamu-B*1703 extracellular domain fused with a BirA substrate peptide (BSP) was amplified from a previously cloned cDNA and inserted into a prokaratic expression vector. In the presence of the antigenic peptide IW9 and light chain β2-microglobulin, the expressed heavy chain was refolded into a soluble monomer. After biotinylation, four monomers were polymerized as a tetramer by phycoerythrin-conjugated streptavidin. The tetramer, having been confirmed to have the right conformation, was a potential tool for investigation of antigen-specific CD8+ T-lymphocytes in SIV vaccine models of Chinese macaques. And our results also suggested that some antigenic peptides reported in Indian-origin macaques could be directly recruited as ligands for construction of Chinese macaque MHC tetramers. PMID:19403061

  15. Association of major histocompatibility complex class 1 chain-related gene a dimorphism with type 1 diabetes and latent autoimmune diabetes in adults in the Algerian population.

    PubMed

    Raache, Rachida; Belanteur, Khadidja; Amroun, Habiba; Benyahia, Amel; Heniche, Amel; Azzouz, Malha; Mimouni, Safia; Gervais, Thibaud; Latinne, Dominique; Boudiba, Aissa; Attal, Nabila; Abbadi, Mohamed Cherif

    2012-04-01

    Major histocompatibility complex class I chain-related gene A (MICA-129) dimorphism was investigated in 73 autoimmune diabetes patients (type 1 diabetes and latent autoimmune diabetes in adults) and 75 controls from Algeria. Only MICA-129 Val allele and MICA-129 Val/Val genotype frequencies were higher among patients than in the control group. Statistical analysis of the estimated extended HLA-DR-DQ-MICA haplotypes shown that individual effects of MICA alleles on HLA-DQ2-DR3-MICA-129 Val/Val and HLA-DQ8-DR4-MICA-129 Val/Val haplotypes were significantly higher in patients than in the control groups. These preliminary data might suggest a relevant role of MICA-129 Val/Val single nucleotide polymorphism (weak/weak binders of NKG2D receptor) in the pathogenesis of T1D and LADA. PMID:22323559

  16. Association of Major Histocompatibility Complex Class 1 Chain-Related Gene A Dimorphism with Type 1 Diabetes and Latent Autoimmune Diabetes in Adults in the Algerian Population

    PubMed Central

    Belanteur, Khadidja; Amroun, Habiba; Benyahia, Amel; Heniche, Amel; Azzouz, Malha; Mimouni, Safia; Gervais, Thibaud; Latinne, Dominique; Boudiba, Aissa; Attal, Nabila; Abbadi, Mohamed Cherif

    2012-01-01

    Major histocompatibility complex class I chain-related gene A (MICA-129) dimorphism was investigated in 73 autoimmune diabetes patients (type 1 diabetes and latent autoimmune diabetes in adults) and 75 controls from Algeria. Only MICA-129 Val allele and MICA-129 Val/Val genotype frequencies were higher among patients than in the control group. Statistical analysis of the estimated extended HLA-DR-DQ-MICA haplotypes shown that individual effects of MICA alleles on HLA-DQ2-DR3-MICA-129 Val/Val and HLA-DQ8-DR4-MICA-129 Val/Val haplotypes were significantly higher in patients than in the control groups. These preliminary data might suggest a relevant role of MICA-129 Val/Val single nucleotide polymorphism (weak/weak binders of NKG2D receptor) in the pathogenesis of T1D and LADA. PMID:22323559

  17. Specialized functions of major histocompatibility complex class I molecules. II. Hmt binds N-formylated peptides of mitochondrial and prokaryotic origin

    PubMed Central

    1991-01-01

    The physiological functions of the mouse telomeric major histocompatibility complex (MHC) class I molecules, including Hmt, are unknown. Hmt presents a polymorphic, N-formylated peptide encoded by the mitochondrial gene ND1 forming the cell surface maternally transmitted antigen (Mta). Because the N-formyl moiety is required for Hmt binding, we proposed that Hmt may function generally in presentation of N-formylated antigens. This hypothesis was validated by a competitive binding assay, demonstrating that synthetic N-formyl peptides from other mitochondrial genes also bound Hmt. Bacteria similarly initiate protein synthesis with N-formylmethionine; indeed, we established that Hmt can also present prokaryotic peptides in an N- formyl-dependent manner. These results indicate biochemical specialization of this MHC-peptide interaction and suggest a unique role for Hmt in prokaryotic host defenses. PMID:1919442

  18. An interferon gamma-regulated protein that binds the interferon-inducible enhancer element of major histocompatibility complex class I genes.

    PubMed Central

    Driggers, P H; Ennist, D L; Gleason, S L; Mak, W H; Marks, M S; Levi, B Z; Flanagan, J R; Appella, E; Ozato, K

    1990-01-01

    Interferons (IFNs) induce transcription of major histocompatibility complex (MHC) class I genes through the conserved IFN consensus sequence (ICS) that contains an IFN response motif shared by many IFN-regulated genes. By screening mouse lambda ZAP expression libraries with the ICS as a probe, we isolated a cDNA clone encoding a protein that binds the ICS, designated ICSBP. Protein blot analysis with labeled oligonucleotide probes showed that ICSBP binds not only the MHC class I ICS but also IFN response motifs of many IFN-regulated genes, as well as a virus-inducible element of the IFN-beta gene. The ICSBP cDNA encodes 424 amino acids and a long 3' untranslated sequence. The N-terminal 115 amino acids correspond to a putative DNA-binding domain and show significant sequence similarity with other cloned IFN response factors (IRF-1 and IRF-2). Because of the structural similarity and shared binding specificity, we conclude that ICSBP is a third member of the IRF gene family, presumably playing a role in IFN- and virus-mediated regulation of many genes. Although IRF-1 and IRF-2 share some similarity in their C-terminal regions, ICSBP shows no similarity to IRF-1 or IRF-2 in this region, suggesting that it is more distantly related. We show that ICSBP mRNA is expressed predominantly in lymphoid tissues and is inducible preferentially by IFN-gamma. The induction by IFN-gamma appears to be predominant in lymphocytes and macrophages, implying that ICSBP plays a regulatory role in cells of the immune system. The presence of multiple factors that bind common IFN response motifs may partly account for the complexity and diversity of IFN action as well as IFN-regulated gene expression. Images PMID:2111015

  19. Generation of Antiviral Major Histocompatibility Complex Class I-Restricted T Cells in the Absence of CD8 Coreceptors ▿

    PubMed Central

    Andrews, Nicolas P.; Pack, Christopher D.; Lukacher, Aron E.

    2008-01-01

    The CD8 coreceptor is important for positive selection of major histocompatibility complex I (MHC-I)-restricted thymocytes and in the generation of pathogen-specific T cells. However, the requirement for CD8 in these processes may not be essential. We previously showed that mice lacking β2-microglobulin are highly susceptible to tumors induced by mouse polyoma virus (PyV), but CD8-deficient mice are resistant to these tumors. In this study, we show that CD8-deficient mice also control persistent PyV infection as efficiently as wild-type mice and generate a substantial virus-specific, MHC-I-restricted, T-cell response. Infection with vesicular stomatitis virus (VSV), which is acutely cleared, also recruited antigen-specific, MHC-I-restricted T cells in CD8-deficient mice. Yet, unlike in VSV infection, the antiviral MHC-I-restricted T-cell response to PyV has a prolonged expansion phase, indicating a requirement for persistent infection in driving T-cell inflation in CD8-deficient mice. Finally, we show that the PyV-specific, MHC-I-restricted T cells in CD8-deficient mice, while maintained long term at near-wild-type levels, are short lived in vivo and have extremely narrow T-cell receptor repertoires. These findings provide a possible explanation for the resistance of CD8-deficient mice to PyV-induced tumors and have implications for the maintenance of virus-specific MHC-I-restricted T cells during persistent infection. PMID:18337581

  20. Major histocompatibility complex class II DAB alleles associated with intestinal parasite load in the vulnerable Chinese egret (Egretta eulophotes).

    PubMed

    Lei, Wei; Zhou, Xiaoping; Fang, Wenzhen; Lin, Qingxian; Chen, Xiaolin

    2016-07-01

    The maintenance of major histocompatibility complex (MHC) polymorphism has been hypothesized to result from many mechanisms such as rare-allele advantage, heterozygote advantage, and allele counting. In the study reported herein, 224 vulnerable Chinese egrets (Egretta eulophotes) were used to examine these hypotheses as empirical results derived from bird studies are rare. Parasite survey showed that 147 (65.63%) individuals were infected with 1-3 helminths, and 82.31% of these infected individuals carried Ascaridia sp. Using asymmetric polymerase chain reaction technique, 10 DAB1, twelve DAB2, and three DAB3 exon 2 alleles were identified at each single locus. A significant association of the rare allele Egeu-DAB2*05 (allele frequency: 0.022) with helminth resistance was found for all helminths, as well as for the most abundant morphotype Ascaridia sp. in the separate analyses. Egeu-DAB2*05 occurred frequently in uninfected individuals, and individuals carrying Egeu-DAB2*05 had significantly lower helminth morphotypes per individual (HMI) (the number of HMI) and the fecal egg count values. Further, the parasite infection measurements were consistently lower in individuals with an intermediate number of different alleles in the duplicated DAB loci. Significantly, heterozygosity within each DAB locus was not correlated with any parasite infection measurements. These results indicate that the diversity in MHC Egeu-DAB gene is associated with intestinal parasite load and maintained by pathogen-driven selection that probably operate through both the rare-allele advantage and the allele counting strategy, and suggest that Egeu-DAB2*05 might be a valuable indicator of better resistance to helminth diseases in the vulnerable Chinese egret. PMID:27386085

  1. Further diversity of the 5' promoter region of the MHC class I-related chain B gene.

    PubMed

    Laza-Briviesca, R; Pearson, H; Saudemont, A; Madrigal, J A; Cox, S T

    2016-02-01

    We have now found a total of 15 individual MICB promoter sequences, varying by combination of 18 polymorphic positions within the MICB minimal promoter sequence. Sequence-based typing and cloning characterized the three new 5' promoter sequences as MICB-P13, MICB-P14 and MICB-P15. PMID:26707708

  2. Respiratory Syncytial Virus Infection Upregulates NLRC5 and Major Histocompatibility Complex Class I Expression through RIG-I Induction in Airway Epithelial Cells

    PubMed Central

    Guo, Xuancheng; Liu, Taixiang; Shi, Hengfei; Wang, Jingjing; Ji, Ping; Wang, Hongwei; Hou, Yayi; Tan, Ren Xiang

    2015-01-01

    ABSTRACT Respiratory syncytial virus (RSV) is the leading cause of acute respiratory tract viral infection in infants, causing bronchiolitis and pneumonia. The host antiviral response to RSV acts via retinoic acid-inducible gene I (RIG-I). We show here that RSV infection upregulates major histocompatibility complex class I (MHC-I) expression through the induction of NLRC5, a NOD-like, CARD domain-containing intracellular protein that has recently been identified as a class I MHC transactivator (CITA). RSV infection of A549 cells promotes upregulation of NLRC5 via beta interferon (IFN-β) production, since the NLRC5-inducing activity in a conditioned medium from RSV-infected A549 cells was removed by antibody to IFN-β, but not by antibody to IFN-γ. RSV infection resulted in RIG-I upregulation and induction of NLRC5 and MHC-I. Suppression of RIG-I induction significantly blocked NLRC5, as well as MHC-I, upregulation and diminished IRF3 activation. Importantly, Vero cells deficient in interferon production still upregulated MHC-I following introduction of the RSV genome by infection or transfection, further supporting a key role for RIG-I. A model is therefore proposed in which the host upregulates MHC-I expression during RSV infection directly via the induction of RIG-I and NLRC5 expression. Since elevated expression of MHC-I molecules can sensitize host cells to T lymphocyte-mediated cytotoxicity or immunopathologic damage, the results have significant implications for the modification of immunity in RSV disease. IMPORTANCE Human respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in infants and young children worldwide. Infection early in life is linked to persistent wheezing and allergic asthma in later life, possibly related to upregulation of major histocompatibility class I (MHC-I) on the cell surface, which facilitates cytotoxic T cell activation and antiviral immunity. Here, we show that RSV infection of lung epithelial

  3. A Novel Class of Bis- and Tris-Chelate Diam(m)inebis(dicarboxylato)platinum(IV) Complexes as Potential Anticancer Prodrugs

    PubMed Central

    Varbanov, Hristo P.; Göschl, Simone; Heffeter, Petra; Theiner, Sarah; Roller, Alexander; Jensen, Frank; Jakupec, Michael A.; Berger, Walter; Galanski, Markus; Keppler, Bernhard K.

    2015-01-01

    A novel class of platinum(IV) complexes of the type [Pt(Am)-(R(COO)2)2], where Am is a chelating diamine or two monodentate am(m)ine ligands and R(COO)2 is a chelating dicarboxylato moiety, was synthesized. For this purpose, the reaction between the corresponding tetrahydroxidoplatinum(IV) precursors and various dicarboxylic acids, such as oxalic, malonic, 3-methylmalonic, and cyclobutanedicarboxylic acid, was utilized. All new compounds were characterized in detail, using 1D and 2D NMR techniques, ESI-MS, FTIR spectroscopy, elemental analysis, TGA, and X-ray diffraction. Their in vitro cytotoxicity was determined in a panel of human tumor cell lines (CH1, SW480 and A549) by means of the MTT colorimetric assay. Furthermore, the lipophilicity and redox properties of the novel complexes were evaluated in order to better understand their pharmacological behavior. The most promising drug candidate, 4b (Pt(DACH)(mal)2), demonstrated low in vivo toxicity but profound anticancer activity against both the L1210 leukemia and CT-26 colon carcinoma models. PMID:25032896

  4. Phosphatidylinositol glycan anchor biosynthesis, class X containing complex promotes cancer cell proliferation through suppression of EHD2 and ZIC1, putative tumor suppressors.

    PubMed

    Nakakido, Makoto; Tamura, Kenji; Chung, Suyoun; Ueda, Koji; Fujii, Risa; Kiyotani, Kazuma; Nakamura, Yusuke

    2016-09-01

    We identified phosphatidylinositol glycan anchor biosynthesis, class X (PIGX), which plays a critical role in the biosynthetic pathway of glycosylphosphatidylinositol (GPI)-anchor motif, to be upregulated highly and frequently in breast cancer cells. Knockdown of PIGX as well as reticulocalbin 1 (RCN1) and reticulocalbin 2 (RCN2), which we found to interact with PIGX and was indicated to regulate calcium-dependent activities, significantly suppressed the growth of breast cancer cells. We also identified PIGX to be a core protein in an RCN1/PIGX/RCN2 complex. Microarray analysis revealed that the expression of two putative tumor suppressor genes, Zic family member 1 (ZIC1) and EH-domain containing 2 (EHD2), were upregulated commonly in cells in which PIGX, RCN1, or RCN2 was knocked down, suggesting that this RCN1/PIGX/RCN2 complex could negatively regulate the expression of these two genes and thereby contribute to human breast carcinogenesis. Our results imply that PIGX may be a good candidate molecule for development of novel anticancer drugs for breast cancer. PMID:27572108

  5. Phosphatidylinositol glycan anchor biosynthesis, class X containing complex promotes cancer cell proliferation through suppression of EHD2 and ZIC1, putative tumor suppressors

    PubMed Central

    Nakakido, Makoto; Tamura, Kenji; Chung, Suyoun; Ueda, Koji; Fujii, Risa; Kiyotani, Kazuma; Nakamura, Yusuke

    2016-01-01

    We identified phosphatidylinositol glycan anchor biosynthesis, class X (PIGX), which plays a critical role in the biosynthetic pathway of glycosylphosphatidylinositol (GPI)-anchor motif, to be upregulated highly and frequently in breast cancer cells. Knockdown of PIGX as well as reticulocalbin 1 (RCN1) and reticulocalbin 2 (RCN2), which we found to interact with PIGX and was indicated to regulate calcium-dependent activities, significantly suppressed the growth of breast cancer cells. We also identified PIGX to be a core protein in an RCN1/PIGX/RCN2 complex. Microarray analysis revealed that the expression of two putative tumor suppressor genes, Zic family member 1 (ZIC1) and EH-domain containing 2 (EHD2), were upregulated commonly in cells in which PIGX, RCN1, or RCN2 was knocked down, suggesting that this RCN1/PIGX/RCN2 complex could negatively regulate the expression of these two genes and thereby contribute to human breast carcinogenesis. Our results imply that PIGX may be a good candidate molecule for development of novel anticancer drugs for breast cancer.

  6. "Racializing" Class

    ERIC Educational Resources Information Center

    Hatt-Echeverria, Beth; Urrieta, Luis, Jr.

    2003-01-01

    In an effort to explore how racial and class oppressions intersect, the authors use their autobiographical narratives to depict cultural and experiential continuity and discontinuity in growing up white working class versus Chicano working class. They specifically focus on "racializing class" due to the ways class is often used as a copout by…

  7. Rhodococcus equi-Infected Macrophages Are Recognized and Killed by CD8+ T Lymphocytes in a Major Histocompatibility Complex Class I-Unrestricted Fashion

    PubMed Central

    Patton, Kristin M.; McGuire, Travis C.; Fraser, Darrilyn G.; Hines, Stephen A.

    2004-01-01

    The goal of this research was to examine the role of cytotoxic T lymphocytes (CTL) in the control of Rhodococcus equi and specifically to determine if R. equi-specific CD8+ CTL occurred in the blood of immune horses. Equine peripheral blood mononuclear cells stimulated with antigen-presenting cells either infected with R. equi or exposed to soluble R. equi antigen lysed R. equi-infected target cells. Lysis was decreased to background by depletion of either CD2+ or CD3+ cells, indicating that the effector cell had a T-lymphocyte, but not NK cell, phenotype. Stimulation induced an increased percentage of CD8+ T cells in the effector population, and depletion of CD8+ T cells resulted in significantly decreased lysis of infected targets. Killing of R. equi-infected macrophages by effector cells was equally effective against autologous and equine leukocyte antigen A (classical major histocompatibility complex [MHC] class I) mismatched targets. To evaluate potential target antigens, target cells were infected with either virulent (80.6-kb plasmid-containing) or avirulent (plasmid-cured) R. equi. The degree of lysis was not altered by the presence of the plasmid, providing evidence that the virulence plasmid, which is required for survival within macrophages, was not necessary for recognition and killing of R. equi-infected cells. These data indicate that immunocompetent adult horses develop R. equi-specific CD8+ CTL, which may play a role in immunity to R. equi. The apparent lack of restriction via classical MHC class I molecules suggests a novel or nonclassical method of antigen processing and presentation, such as presentation by CD1 or other nonclassical MHC molecules. PMID:15557631

  8. Dominating expression of negative regulatory factors downmodulates major histocompatibility complex Class-II expression on dendritic cells in chronic hepatitis C infection

    PubMed Central

    Tomer, Shallu; Chawla, Yogesh K; Duseja, Ajay; Arora, Sunil K

    2016-01-01

    AIM: To elucidate the molecular mechanisms leading to development of functionally impaired dendritic cells (DCs) in chronic hepatitis C (CHC) patients infected with genotype 3 virus. METHODS: This prospective study was conducted on the cohorts of CHC individuals identified as responders or non-responders to antiviral therapy. Myeloid DCs were isolated from the peripheral blood of each subject using CD1c (BDCA1)+ DC isolation Kit. Monocytes from healthy donor were cultured with DC growth factors such as IL-4 and GM-CSF either in the presence or absence of hepatitis C virus (HCV) viral proteins followed by LPS stimulation. Phenotyping was done by flowcytometry and gene expression profiling was evaluated by real-time PCR. RESULTS: Non-responders [sustained virological response (SVR)-ve] to conventional antiviral therapy had significantly higher expression of genes associated with interferon responsive element such as IDO1 and PD-L1 (6-fold) and negative regulators of JAK-STAT pathway such as SOCS (6-fold) as compared to responders (SVR+ve) to antiviral therapy. The down-regulated genes in non-responders included factors involved in antigen processing and presentation mainly belonging to major histocompatibility complex (MHC) Class-II family as HLA-DP, HLA-DQ (2-fold) and superoxide dismutase (2-fold). Cells grown in the presence of HCV viral proteins had genes down-regulated for factors involved in innate response, interferon signaling, DC maturation and co-stimulatory signaling to T-cells, while the genes for cytokine signaling and Toll-like receptors (4-fold) were up-regulated as compared to cells grown in absence of viral proteins. CONCLUSION: Underexpressed MHC class-II genes and upregulated negative regulators in non-responders indicate diminished capacity to present antigen and may constitute mechanism of functionally defective state of DCs. PMID:27298560

  9. Histone deacetylase 1/mSin3A disrupts gamma interferon-induced CIITA function and major histocompatibility complex class II enhanceosome formation.

    PubMed

    Zika, Eleni; Greer, Susanna F; Zhu, Xin-Sheng; Ting, Jenny P-Y

    2003-05-01

    The class II transactivator (CIITA) is a master transcriptional regulator of major histocompatibility complex class II (MHC-II) promoters. CIITA does not bind DNA, but it interacts with the transcription factors RFX5, NF-Y, and CREB and associated chromatin-modifying enzymes to form an enhanceosome. This report examines the effects of histone deacetylases 1 and 2 (HDAC1/HDAC2) on MHC-II gene induction by gamma interferon (IFN-gamma) and CIITA. The results show that an inhibitor of HDACs, trichostatin A, enhances IFN-gamma-induced MHC-II expression, while HDAC1/HDAC2 inhibits IFN-gamma- and CIITA-induced MHC-II gene expression. mSin3A, a corepressor of HDAC1/HDAC2, is important for this inhibition, while NcoR, a corepressor of HDAC3, is not. The effect of this inhibition is directed at CIITA, since HDAC1/HDAC2 reduces transactivation by a GAL4-CIITA fusion protein. CIITA binds to overexpressed and endogenous HDAC1, suggesting that HDAC and CIITA may affect each other by direct or indirect association. Inhibition of HDAC activity dramatically increases the association of NF-YB and RFX5 with CIITA, the assembly of CIITA, NF-YB, and RFX5 enhanceosome, and the extent of H3 acetylation at the MHC-II promoter. These results suggest a model where HDAC1/HDAC2 affect the function of CIITA through a disruption of MHC-II enhanceosome and relevant coactivator-transcription factor association and provide evidence that CIITA may act as a molecular switch to modulate MHC-II transcription by coordinating the functions of both histone acetylases and HDACs. PMID:12697811

  10. Kaposi's Sarcoma-Associated Herpesvirus Viral Interferon Regulatory Factor 3 Inhibits Gamma Interferon and Major Histocompatibility Complex Class II Expression▿†

    PubMed Central

    Schmidt, Katharina; Wies, Effi; Neipel, Frank

    2011-01-01

    Kaposi's sarcoma-associated herpesvirus (KSHV) carries four genes with homology to human interferon regulatory factors (IRFs). One of these IRFs, the viral interferon regulatory factor 3 (vIRF-3), is expressed in latently infected primary effusion lymphoma (PEL) cells and required for their continuous proliferation. Moreover, vIRF-3 is known to be involved in modulation of the type I interferon (IFN) response. We now show that vIRF-3 also interferes with the type II interferon system and antigen presentation to the adaptive immune system. Starting with an analysis of the transcriptome, we show that vIRF-3 inhibits expression of major histocompatibility complex class II (MHC II) molecules: small interfering RNA (siRNA)-mediated knockdown of vIRF-3 in KSHV-infected PEL cell lines resulted in increased MHC II levels; overexpression of vIRF-3 in KSHV-negative B cells leads to downmodulation of MHC II. This regulation could be traced back to inhibition of class II transactivator (CIITA) transcription by vIRF-3. Reporter assays revealed that the gamma interferon (IFN-γ)-sensitive CIITA promoters PIV and PIII were inhibited by vIRF-3. Consistently, IFN-γ levels increased upon vIRF-3 knockdown in PEL cells. IFN-γ regulation by vIRF-3 was confirmed in reporter assays as well as by upregulation of typical IFN-γ target genes upon knockdown of vIRF-3 in PEL cells. In summary, we conclude that vIRF-3 contributes to the viral immunoevasion by downregulation of IFN-γ and CIITA and thus MHC II expression. PMID:21345951

  11. The QTL within the H2 Complex Involved in the Control of Tuberculosis Infection in Mice Is the Classical Class II H2-Ab1 Gene

    PubMed Central

    Logunova, Nadezhda; Korotetskaya, Maria; Polshakov, Vladimir; Apt, Alexander

    2015-01-01

    The level of susceptibility to tuberculosis (TB) infection depends upon allelic variations in numerous interacting genes. In our mouse model system, the whole-genome quantitative trait loci (QTLs) scan revealed three QTLs involved in TB control on chromosomes 3, 9, and in the vicinity of the H2 complex on chromosome 17. For the present study, we have established a panel of new congenic, MHC-recombinant mouse strains bearing differential small segments of chromosome 17 transferred from the TB-susceptible I/St (H2 j) strain onto the genetic background of TB-resistant C57BL/6 (B6) mice (H2 b). This allowed narrowing the QTL interval to 17Ch: 33, 77–34, 34 Mb, containing 36 protein-encoding genes. Cloning and sequencing of the H2 j allelic variants of these genes demonstrated profound polymorphic variations compare to the H2 b haplotype. In two recombinant strains, B6.I-249.1.15.100 and B6.I-249.1.15.139, recombination breakpoints occurred in different sites of the H2-Aβ 1 gene (beta-chain of the Class II heterodimer H2-A), providing polymorphic variations in the domain β1 of the Aβ-chain. These variations were sufficient to produce different TB-relevant phenotypes: the more susceptible B6.I-249.1.15.100 strain demonstrated shorter survival time, more rapid body weight loss, higher mycobacterial loads in the lungs and more severe lung histopathology compared to the more resistant B6.I-249.1.15.139 strain. CD4+ T cells recognized mycobacterial antigens exclusively in the context of the H2-A Class II molecule, and the level of IFN-γ-producing CD4+ T cells in the lungs was significantly higher in the resistant strain. Thus, we directly demonstrated for the first time that the classical H2- Ab1 Class II gene is involved in TB control. Molecular modeling of the H2-Aj product predicts that amino acid (AA) substitutions in the Aβ-chain modify the motif of the peptide–MHC binding groove. Moreover, unique AA substitutions in both α- and β-chains of the H2-Aj molecule

  12. Major histocompatibility complex class I-intercellular adhesion molecule-1 association on the surface of target cells: implications for antigen presentation to cytotoxic T lymphocytes.

    PubMed

    Lebedeva, Tatiana; Anikeeva, Nadja; Kalams, Spyros A; Walker, Bruce D; Gaidarov, Ibragim; Keen, James H; Sykulev, Yuri

    2004-12-01

    Polarization and segregation of the T-cell receptor (TCR) and integrins upon productive cytotoxic T-lymphocyte (CTL) target cell encounters are well documented. Much less is known about the redistribution of major histocompatibility complex class I (MHC-I) and intercellular adhesion molecule-1 (ICAM-1) proteins on target cells interacting with CTLs. Here we show that human leucocyte antigen-A2 (HLA-A2) MHC-I and ICAM-1 are physically associated and recovered from both the raft fraction and the fraction of soluble membranes of target cells. Conjugation of target cells with surrogate CTLs, i.e. polystyrene beads loaded with antibodies specific for HLA-A2 and ICAM-1, induced the accumulation of membrane rafts, and beads loaded with ICAM-1-specific antibodies caused the selective recruitment of HLA-A2 MHC-I at the contact area of the target cells. Disruption of raft integrity on target cells led to a release of HLA-A2 and ICAM-1 from the raft fraction, abatement of HLA-A2 polarization, and diminished the ability of target cells bearing viral peptides to induce a Ca(2+) flux in virus-specific CTLs. These data suggest that productive engagement of ICAM-1 on target cells facilitates the polarization of MHC-I at the CTL-target cell interface, augmenting presentation of cognate peptide-MHC (pMHC) complexes to CTLs. We propose that ICAM-1-MHC-I association on the cell membrane is a mechanism that enhances the linkage between antigen recognition and early immunological synapse formation. PMID:15554924

  13. Major Histocompatibility Complex Class II Inhibits Fas Antigen-Mediated Gastric Mucosal Cell Apoptosis through Actin-Dependent Inhibition of Receptor Aggregation

    PubMed Central

    Stoicov, Calin; Cai, Xun; Li, Hanchen; Klucevsek, Kristine; Carlson, Jane; Saffari, Reza; Houghton, JeanMarie

    2005-01-01

    Escape from normal apoptotic controls is thought to be essential for the development of cancer. During Helicobacter pylori infection, the leading cause of gastric cancer, activation of the Fas antigen (Fas Ag) apoptotic pathway is responsible for early atrophy and tissue loss. As disease progresses, metaplastic and dysplastic glands arise which express Fas Ag but are resistant to apoptosis and are believed to be the precursor cells for adenocarcinoma. In this report, we show that one mechanism of acquired Fas resistance is inhibition of receptor aggregation via a major histocompatibility complex class II (MHCII)-mediated, actin-dependent mechanism. For these studies we used the well-described C57BL/6 mouse model of Helicobacter pylori and Helicobacter felis infection. Under normal conditions, Fas Ag is expressed at low levels, and MHCII expression on gastric mucosal cells is negligible. With infection and inflammation, both receptors are upregulated, and 6.1% of gastric mucosal cells express MHCII in combination with Fas Ag. Using the rat gastric mucosal cell line RGM-1 transfected with murine Fas Ag and MHCIIαβ chains, we demonstrate that MHCII prevents Fas receptor aggregation and inhibits Fas-mediated signaling through its effects on the actin cytoskeleton. Depolymerization of actin with cytochalasin D allows receptors to aggregate and restores Fas sensitivity. These findings offer one mechanism by which gastric mucosal cells acquire Fas resistance. PMID:16177302

  14. Crystal structure of Fushi tarazu factor 1 ligand binding domain/Fushi tarazu peptide complex identifies new class of nuclear receptors.

    PubMed

    Yoo, Jiho; Ko, Sunggeon; Kim, Hyeyon; Sampson, Heidi; Yun, Ji-Hye; Choe, Kwang-Min; Chang, Iksoo; Arrowsmith, Cheryl H; Krause, Henry M; Cho, Hyun-Soo; Lee, Weontae

    2011-09-01

    The interaction between the orphan nuclear receptor FTZ-F1 (Fushi tarazu factor 1) and the segmentation gene protein FTZ is critical for specifying alternate parasegments in the Drosophila embryo. Here, we have determined the structure of the FTZ-F1 ligand-binding domain (LBD)·FTZ peptide complex using x-ray crystallography. Strikingly, the ligand-binding pocket of the FTZ-F1 LBD is completely occupied by helix 6 (H6) of the receptor, whereas the cofactor FTZ binds the co-activator cleft site of the FTZ-F1 LBD. Our findings suggest that H6 is essential for transcriptional activity of FTZ-F1; this is further supported by data from mutagenesis and activity assays. These data suggest that FTZ-F1 might belong to a novel class of ligand-independent nuclear receptors. Our findings are intriguing given that the highly homologous human steroidogenic factor-1 and liver receptor homolog-1 LBDs exhibit sizable ligand-binding pockets occupied by putative ligand molecules. PMID:21775434

  15. Low Major Histocompatibility Complex Class II Variation in the Endangered Indo-Pacific Humpback Dolphin (Sousa chinensis): Inferences About the Role of Balancing Selection.

    PubMed

    Zhang, Xiyang; Lin, Wenzhi; Zhou, Ruilian; Gui, Duan; Yu, Xinjian; Wu, Yuping

    2016-03-01

    It has been widely reported that the major histocompatibility complex (MHC) is under balancing selection due to its immune function across terrestrial and aquatic mammals. The comprehensive studies at MHC and other neutral loci could give us a synthetic evaluation about the major force determining genetic diversity of species. Previously, a low level of genetic diversity has been reported among the Indo-Pacific humpback dolphin (Sousa chinensis) in the Pearl River Estuary (PRE) using both mitochondrial marker and microsatellite loci. Here, the expression and sequence polymorphism of 2 MHC class II genes (DQB and DRB) in 32 S. chinensis from PRE collected between 2003 and 2011 were investigated. High ratios of non-synonymous to synonymous substitution rates, codon-based selection analysis, and trans-species polymorphism (TSP) support the hypothesis that balancing selection acted on S. chinensis MHC sequences. However, only 2 haplotypes were detected at either DQB or DRB loci. Moreover, the lack of deviation from the Hardy-Weinberg expectation at DRB locus combined with the relatively low heterozygosity at both DQB locus and microsatellite loci suggested that balancing selection might not be sufficient, which further suggested that genetic drift associated with historical bottlenecks was not mitigated by balancing selection in terms of the loss of MHC and neutral variation in S. chinensis. The combined results highlighted the importance of maintaining the genetic diversity of the endangered S. chinensis. PMID:26787544

  16. Molecular components of the B cell antigen receptor complex of class IgD differ partly from those of IgM.

    PubMed Central

    Wienands, J; Hombach, J; Radbruch, A; Riesterer, C; Reth, M

    1990-01-01

    Two classes of immunoglobulin, IgM and IgD, are present as antigen receptors on the surface of mature B lymphocytes. We show here that IgD molecules are noncovalently associated in the B cell membrane with a heterodimer consisting of two proteins of 35 kd (IgD-alpha) and 39 kd (Ig-beta), respectively. The two novel proteins are not found in the IgD-expressing myeloma J558L delta m, which fails to bring IgD antigen receptor onto the cell surface. In a surface IgD positive variant line of this myeloma, however, membrane-bound IgD molecules are associated with the heterodimer, suggesting that the formation of an antigen receptor complex is required for surface IgD expression. We further demonstrate that the IgD-associated heterodimer differs partly from that of the IgM antigen receptor and that its binding to the heavy chain only requires the presence of the last constant domain and the transmembrane part of the delta m chain. Images Fig. 3. Fig. 5. Fig. 6. Fig. 7. PMID:2303036

  17. Allelic and haplotype variation of major histocompatibility complex class II DRB1 and DQB loci in the St Lawrence beluga (Delphinapterus leucas).

    PubMed

    1999-07-01

    In order to assess levels of major histocompatibility complex (Mhc) variation within the St Lawrence beluga (Delphinapterus leucas) the variation at the beluga Mhc DRB1 class II locus was assessed by single-strand conformation polymorphism (SSCP) analysis of the peptide-binding region for 313 whales collected from 13 sampling locations across North America. In addition, samples from west Greenland and the St Lawrence were also typed at the DQB locus, allowing comparison to a previous study and assessment of linkage disequilibrium of alleles at the two loci. Comparisons of DRB1 and DQB allele frequencies among all sampling locations indicated genetic structure (alpha < 0.005). Most of this structure resulted from differences between the different wintering groups. Significant genetic structure (alpha = 0.05) exists among each pair of the following groups at both the DRB1 and DQB loci; St Lawrence, Hudson Strait, Bering Sea, Cunningham Inlet, and Davis Strait (minus Cunningham Inlet), except the St Lawrence and Hudson Strait for the DQB locus. In the St Lawrence population, six of the eight DRB1 alleles are present representing all five known allelic lineages. Evidence of linkage disequilibrium between the DRB1 and DQB is present in two sampling locations, the St Lawrence and Nuussuaq (alpha = 0.05). Analysis of probable DRB1-DQB haplotypes among groups of beluga suggests a haplotype reduction in the St Lawrence. PMID:10447854

  18. The production and crystallization of the human leukocyte antigen class II molecules HLA-DQ2 and HLA-DQ8 complexed with deamidated gliadin peptides implicated in coeliac disease

    PubMed Central

    Henderson, Kate N.; Reid, Hugh H.; Borg, Natalie A.; Broughton, Sophie E.; Huyton, Trevor; Anderson, Robert P.; McCluskey, James; Rossjohn, Jamie

    2007-01-01

    The major histocompatibility complex (MHC) class II molecules HLA-DQ2 and HLA-DQ8 are key risk factors in coeliac disease, as they bind deamidated gluten peptides that are subsequently recognized by CD4+ T cells. Here, the production and crystallization of both HLA-DQ2 and HLA-DQ8 in complex with the deamidated gliadin peptides DQ2 α-I (PQPELPYPQ) and DQ8 α-I (EGSFQPSQE), respectively, are reported. PMID:18084083

  19. Detection and Quantification of CD4+ T Cells with Specificity for a New Major Histocompatibility Complex Class II-Restricted Influenza A Virus Matrix Protein Epitope in Peripheral Blood of Influenza Patients

    PubMed Central

    Linnemann, Thomas; Jung, Günther; Walden, Peter

    2000-01-01

    FVFTLTVPS was identified as the core sequence of a new major histocompatibility complex class II-restricted T-cell epitope of influenza virus matrix protein. Epitope-specific CD4+ T cells were detected in the peripheral blood of patients with frequencies of up to 0.94%, depending on the number of additional terminal amino acids. PMID:10954576

  20. Equine Herpesvirus 1 Multiply Inserted Transmembrane Protein pUL43 Cooperates with pUL56 in Downregulation of Cell Surface Major Histocompatibility Complex Class I

    PubMed Central

    Huang, Teng; Ma, Guanggang

    2015-01-01

    ABSTRACT Herpesviruses have evolved an array of strategies to counteract antigen presentation by major histocompatibility complex class I (MHC-I). Previously, we identified pUL56 of equine herpesvirus 1 (EHV-1) as one major determinant of the downregulation of cell surface MHC-I (G. Ma, S. Feineis, N. Osterrieder, and G. R. Van de Walle, J. Virol. 86:3554–3563, 2012, http://dx.doi.org/10.1128/JVI.06994-11; T. Huang, M. J. Lehmann, A. Said, G. Ma, and N. Osterrieder, J. Virol. 88:12802–12815, 2014, http://dx.doi.org/10.1128/JVI.02079-14). Since pUL56 was able to exert its function only in the context of virus infection, we hypothesized that pUL56 cooperates with another viral protein. Here, we generated and screened a series of EHV-1 single-gene deletion mutants and found that the pUL43 orthologue was required for downregulation of cell surface MHC-I expression at the same time of infection as when pUL56 exerts its function. We demonstrate that the absence of pUL43 was not deleterious to virus growth and that expression of pUL43 was detectable from 2 h postinfection (p.i.) but decreased after 8 h p.i. due to lysosomal degradation. pUL43 localized within Golgi vesicles and required a unique hydrophilic N-terminal domain to function properly. Finally, coexpression of pUL43 and pUL56 in transfected cells reduced the cell surface expression of MHC-I. This process was dependent on PPxY motifs present in pUL56, suggesting that late domains are required for pUL43- and pUL56-dependent sorting of MHC class I for lysosomal degradation. IMPORTANCE We describe here that the poorly characterized herpesviral protein pUL43 is involved in downregulation of cell surface MHC-I. pUL43 is an early protein and degraded in lysosomes. pUL43 resides in the Golgi vesicles and needs an intact N terminus to induce MHC-I downregulation in infected cells. Importantly, pUL43 and pUL56 cooperate to reduce MHC-I expression on the surface of transfected cells. Our results suggest a model for

  1. Key Role of Toll-Like Receptor 2 in the Inflammatory Response and Major Histocompatibility Complex Class II Downregulation in Brucella abortus-Infected Alveolar Macrophages

    PubMed Central

    Ferrero, Mariana C.; Hielpos, M. Soledad; Carvalho, Natalia B.; Barrionuevo, Paula; Corsetti, Patricia P.; Giambartolomei, Guillermo H.; Oliveira, Sergio C.

    2014-01-01

    Alveolar macrophages (AM) seem to constitute the main cellular target of inhaled brucellae. Here, we show that Brucella abortus invades and replicates in murine AM without inducing cytotoxicity. B. abortus infection induced a statistically significant increase of tumor necrosis factor alpha (TNF-α), CXCL1 or keratinocyte chemoattractant (KC), interleukin-1β (IL-1β), IL-6, and IL-12 in AM from C57BL/6 mice and BALB/c mice, but these responses were generally weaker and/or delayed compared to those elicited in peritoneal macrophages. Studies using knockout mice for TLR2, TLR4, and TLR9 revealed that TNF-α and KC responses were mediated by TLR2 recognition. Brucella infection reduced in a multiplicity of infection-dependent manner the expression of major histocompatibility complex class II (MHC-II) molecules induced by gamma interferon (IFN-γ) in AM. The same phenomenon was induced by incubation with heat-killed B. abortus (HKBA) or the lipidated form of the 19-kDa outer membrane protein of Brucella (L-Omp19), and it was shown to be mediated by TLR2 recognition. In contrast, no significant downregulation of MHC-II was induced by either unlipidated Omp19 or Brucella LPS. In a functional assay, treatment of AM with either L-Omp19 or HKBA reduced the MHC-II-restricted presentation of OVA peptides to specific T cells. One week after intratracheal infection, viable B. abortus was detected in AM from both wild-type and TLR2 KO mice, but CFU counts were higher in the latter. These results suggest that B. abortus survives in AM after inhalatory infection in spite of a certain degree of immune control exerted by the TLR2-mediated inflammatory response. Both the modest nature of the latter and the modulation of MHC-II expression by the bacterium may contribute to such survival. PMID:24478078

  2. Equine herpesvirus type 4 UL56 and UL49.5 proteins downregulate cell surface major histocompatibility complex class I expression independently of each other.

    PubMed

    Said, Abdelrahman; Azab, Walid; Damiani, Armando; Osterrieder, Nikolaus

    2012-08-01

    Major histocompatibility complex class I (MHC-I) molecules are critically important in the host defense against various pathogens through presentation of viral peptides to cytotoxic T lymphocytes (CTLs), a process resulting in the destruction of virus-infected cells. Herpesviruses interfere with CTL-mediated elimination of infected cells by various mechanisms, including inhibition of peptide transport and loading, perturbation of MHC-I trafficking, and rerouting and proteolysis of cell surface MHC-I. In this study, we show that equine herpesvirus type 4 (EHV-4) modulates MHC-I cell surface expression through two different mechanisms. First, EHV-4 can lead to a significant downregulation of MHC-I expression at the cell surface through the product of ORF1, a protein expressed with early kinetics from a gene that is homologous to herpes simplex virus 1 UL56. The EHV-4 UL56 protein reduces cell surface MHC-I as early as 4 h after infection. Second, EHV-4 can interfere with MHC-I antigen presentation, starting at 6 h after infection, by inhibition of the transporter associated with antigen processing (TAP) through its UL49.5 protein. Although pUL49.5 has no immediate effect on overall surface MHC-I levels in infected cells, it blocks the supply of antigenic peptides to the endoplasmic reticulum (ER) and transport of peptide-loaded MHC-I to the cell surface. Taken together, our results show that EHV-4 encodes at least two viral immune evasion proteins: pUL56 reduces MHC-I molecules on the cell surface at early times after infection, and pUL49.5 interferes with MHC-I antigen presentation by blocking peptide transport in the ER. PMID:22623773

  3. Antigen-Specific Signaling by a Soluble, Dimeric Peptide/Major Histocompatibility Complex Class II/Fc Chimera Leading to T Helper Cell Type 2 Differentiation

    PubMed Central

    Casares, Sofia; Zong, Cong S.; Radu, Dorel L.; Miller, Alexander; Bona, Constantin A.; Brumeanu, Teodor-Doru

    1999-01-01

    Interaction between a T cell receptor (TCR) and various ligands, i.e., anti-TCR antibodies, superantigens, peptides, or altered peptide ligands in the context of major histocompatibility complex (MHC) molecules can trigger different T helper cell (Th) effector functions. Herein, we studied the T cell response induced by a soluble, dimeric peptide/MHC class II chimera, namely hemagglutinin (HA)110-120/I-Edαβ/Fcγ2a (DEF). We have previously demonstrated that the soluble DEF molecule binds stably and specifically to HA110-120–specific TCRs expressed by a T cell hybridoma. Administration of DEF in vivo induced differentiation of resting and activated peptide-specific T cells toward a Th2 response, as indicated by the increase of interleukin (IL)-4, IL-10, and specific immunoglobulin (Ig)G1 antibodies and decrease of IL-2, specific IgG2a antibodies, and cytotoxic T lymphocyte activity. In contrast to HA110-120 peptide presented by the DEF molecule to T cells, the nominal synthetic peptide induced a predominant Th1 response, and the PR8 virus–derived HA110-120 peptides induced a mixed Th1/Th2 response. Independent of antigen processing, soluble DEF was almost 2 logs more potent in stimulating cognate T cells than the nominal peptide. Polarization of cognate T cells toward the Th2 response occurred upon interaction of soluble DEF with TCR and CD4 molecules followed by early activation of p56lck and ZAP-70 tyrosine kinases, and negative signaling of the signal transducer and activator of transcription (STAT)4 pathway of Th1 differentiation. DEF-like molecules may provide a new tool to study the mechanisms of signaling toward Th2 differentiation and may also provide a potential immunotherapeutic approach to modulate autoreactive T cells toward protective Th2 immune responses. PMID:10449525

  4. In silico prediction of peptide binding affinity to class I mouse major histocompatibility complexes: a comparative molecular similarity index analysis (CoMSIA) study.

    PubMed

    Hattotuwagama, Channa K; Doytchinova, Irini A; Flower, Darren R

    2005-01-01

    Current methods for the in silico identification of T cell epitopes (which form the basis of many vaccines, diagnostics, and reagents) rely on the accurate prediction of peptide-major histocompatibility complex (MHC) affinity. A three-dimensional quantitative structure-activity relationship (3D-QSAR) for the prediction of peptide binding to class I MHC molecules was established using the comparative molecular similarity index analysis (CoMSIA) method. Three MHC alleles were studied: H2-D(b), H2-K(b), and H2-K(k). Models were produced for each allele. Each model consisted of five physicochemical descriptors-steric bulk, electrostatic potentials, hydrophobic interactions, and hydrogen-bond donor and hydrogen-bond acceptor abilities. The models have an acceptable level of predictivity: cross-validation leave-one-out statistical terms q2 and SEP (standard error of prediction) ranged between 0.490 and 0.679 and between 0.525 and 0.889, respectively. The non-cross-validated statistical terms r2 and SEE (standard error of estimate) ranged between 0.913 and 0.979 and between 0.167 and 0.248, respectively. The use of coefficient contour maps, which indicate favored and disfavored areas for each position of the MHC-bound peptides, allowed the binding specificity of each allele to be identified, visualized, and understood. The present study demonstrates the effectiveness of CoMSIA as a method for studying peptide-MHC interactions. The peptides used in this study are available on the Internet (http://www.jenner.ac.uk/AntiJen). The partial least-squares method is available commercially in the SYBYL molecular modeling software package. PMID:16180918

  5. Parasite Manipulation of the Invariant Chain and the Peptide Editor H2-DM Affects Major Histocompatibility Complex Class II Antigen Presentation during Toxoplasma gondii Infection

    PubMed Central

    Leroux, Louis-Philippe; Nishi, Manami; El-Hage, Sandy; Fox, Barbara A.; Bzik, David J.

    2015-01-01

    Toxoplasma gondii is an obligate intracellular protozoan parasite. This apicomplexan is the causative agent of toxoplasmosis, a leading cause of central nervous system disease in AIDS. It has long been known that T. gondii interferes with major histocompatibility complex class II (MHC-II) antigen presentation to attenuate CD4+ T cell responses and establish persisting infections. Transcriptional downregulation of MHC-II genes by T. gondii was previously established, but the precise mechanisms inhibiting MHC-II function are currently unknown. Here, we show that, in addition to transcriptional regulation of MHC-II, the parasite modulates the expression of key components of the MHC-II antigen presentation pathway, namely, the MHC-II-associated invariant chain (Ii or CD74) and the peptide editor H2-DM, in professional antigen-presenting cells (pAPCs). Genetic deletion of CD74 restored the ability of infected dendritic cells to present a parasite antigen in the context of MHC-II in vitro. CD74 mRNA and protein levels were, surprisingly, elevated in infected cells, whereas MHC-II and H2-DM expression was inhibited. CD74 accumulated mainly in the endoplasmic reticulum (ER), and this phenotype required live parasites, but not active replication. Finally, we compared the impacts of genetic deletion of CD74 and H2-DM genes on parasite dissemination toward lymphoid organs in mice, as well as activation of CD4+ T cells and interferon gamma (IFN-γ) levels during acute infection. Cyst burdens and survival during the chronic phase of infection were also evaluated in wild-type and knockout mice. These results highlight the fact that the infection is influenced by multiple levels of parasite manipulation of the MHC-II antigen presentation pathway. PMID:26195549

  6. Genetic drift vs. natural selection in a long-term small isolated population: major histocompatibility complex class II variation in the Gulf of California endemic porpoise (Phocoena sinus).

    PubMed

    Munguia-Vega, Adrian; Esquer-Garrigos, Yareli; Rojas-Bracho, Lorenzo; Vazquez-Juarez, Ricardo; Castro-Prieto, Aines; Flores-Ramirez, Sergio

    2007-10-01

    Although many studies confirm long-term small isolated populations (e.g. island endemics) commonly sustain low neutral genetic variation as a result of genetic drift, it is less clear how selection on adaptive or detrimental genes interplay with random forces. We investigated sequence variation at two major histocompatibility complex (Mhc) class II loci on a porpoise endemic to the upper Gulf of California, México (Phocoena sinus, or vaquita). Its unique declining population is estimated around 500 individuals. Single-strand conformation polymorphism analysis revealed one putative functional allele fixed at the locus DQB (n = 25). At the DRB locus, we found two presumed functional alleles (n = 29), differing by a single nonsynonymous nucleotide substitution that could increase the stability at the dimer interface of alphabeta-heterodimers on heterozygous individuals. Identical trans-specific DQB1 and DRB1 alleles were identified between P. sinus and its closest relative, the Burmeister's porpoise (Phocoena spinipinnis). Comparison with studies on four island endemic mammals suggests fixation of one allele, due to genetic drift, commonly occurs at the DQA or DQB loci (effectively neutral). Similarly, deleterious alleles of small effect are also effectively neutral and can become fixed; a high frequency of anatomical malformations on vaquita gave empirical support to this prediction. In contrast, retention of low but functional polymorphism at the DRB locus was consistent with higher selection intensity. These observations indicated natural selection could maintain (and likely also purge) some crucial alleles even in the face of strong and prolonged genetic drift and inbreeding, suggesting long-term small populations should display low inbreeding depression. Low levels of Mhc variation warn about a high susceptibility to novel pathogens and diseases in vaquita. PMID:17727623

  7. Genetic Variation of the Major Histocompatibility Complex (MHC Class II B Gene) in the Threatened Hume’s Pheasant, Syrmaticus humiae

    PubMed Central

    Chen, Weicai; Bei, Yongjian; Li, Hanhua

    2015-01-01

    Major histocompatibility complex (MHC) genes are the most polymorphic genes in vertebrates and encode molecules that play a crucial role in pathogen resistance. As a result of their diversity, they have received much attention in the fields of evolutionary and conservation biology. Here, we described the genetic variation of MHC class II B (MHCIIB) exon 2 in a wild population of Hume’s pheasant (Syrmaticus humiae), which has suffered a dramatic decline in population over the last three decades across its ranges in the face of heavy exploitation and habitat loss. Twenty-four distinct alleles were found in 73 S. humiae specimens. We found seven shared alleles among four geographical groups as well as six rare MHCIIB alleles. Most individuals displayed between one to five alleles, suggesting that there are at least three MHCIIB loci of the Hume’s pheasant. The dN ⁄ dS ratio at putative antigen-binding sites (ABS) was significantly greater than one, indicating balancing selection is acting on MHCIIB exon 2. Additionally, recombination and gene conversion contributed to generating MHCIIB diversity in the Hume’s pheasant. One to three recombination events and seventy-five significant gene conversion events were observed within the Hume’s pheasant MHCIIB loci. The phylogenetic tree and network analysis revealed that the Hume’s pheasant alleles do not cluster together, but are scattered through the tree or network indicating a trans-species evolutionary mode. These findings revealed the evolution of the Hume’s pheasant MHC after suffering extreme habitat fragmentation. PMID:25629763

  8. Major Histocompatibility Complex Class I Downregulation Induced by Equine Herpesvirus Type 1 pUL56 Is through Dynamin-Dependent Endocytosis

    PubMed Central

    Huang, Teng; Lehmann, Maik J.; Said, Abdelrahman; Ma, Guanggang

    2014-01-01

    ABSTRACT Equine herpesvirus type 1 (EHV-1) downregulates cell surface expression of major histocompatibility complex class I (MHC-I) in infected cells. We have previously shown that pUL56 encoded by the EHV-1 ORF1 gene regulates the process (G. Ma, S. Feineis, N. Osterrieder, and G. R. Van de Walle, J. Virol. 86:3554–3563, 2012, doi:http://dx.doi.org/10.1128/JVI.06994-11). Here, we report that cell surface MHC-I in EHV-1-infected cells is internalized and degraded in the lysosomal compartment in a pUL56-dependent fashion. pUL56-induced MHC-I endocytosis required dynamin and tyrosine kinase but was independent of clathrin and caveolin-1, the main constituents of the clathrin- and raft/caveola-mediated endocytosis pathways, respectively. Downregulation of cell surface MHC-I was significantly inhibited by the ubiquitin-activating enzyme E1 inhibitor PYR41, indicating that ubiquitination is essential for the process. Finally, we show that downregulation is not specific for MHC-I and that other molecules, including CD46 and CD63, are also removed from the cell surface in a pUL56-dependent fashion. IMPORTANCE We show that alphaherpesvirus induces MHC-I downregulation through endocytosis, which is mediated by pUL56. The dynamin-dependent endocytic pathway is responsible for MHC-I internalization in infected cells. Furthermore, we discovered that this endocytic process can be disrupted by the inhibiting ubiquitin-activating E1 enzyme, which is indispensable for ubiquitination. Finally, pUL56 action extends to a number of cell surface molecules that are significant for host immunity. Therefore, the protein may exert a more general immunomodulatory effect. PMID:25165105

  9. Bordetella pertussis Proteins Dominating the Major Histocompatibility Complex Class II-Presented Epitope Repertoire in Human Monocyte-Derived Dendritic Cells

    PubMed Central

    Stenger, Rachel M.; Meiring, Hugo D.; Kuipers, Betsy; Poelen, Martien; van Gaans-van den Brink, Jacqueline A. M.; Boog, Claire J. P.; de Jong, Ad P. J. M.

    2014-01-01

    Knowledge of naturally processed Bordetella pertussis-specific T cell epitopes may help to increase our understanding of the basis of cell-mediated immune mechanisms to control this reemerging pathogen. Here, we elucidate for the first time the dominant major histocompatibility complex (MHC) class II-presented B. pertussis CD4+ T cell epitopes, expressed on human monocyte-derived dendritic cells (MDDC) after the processing of whole bacterial cells by use of a platform of immunoproteomics technology. Pertussis epitopes identified in the context of HLA-DR molecules were derived from two envelope proteins, i.e., putative periplasmic protein (PPP) and putative peptidoglycan-associated lipoprotein (PAL), and from two cytosolic proteins, i.e., 10-kDa chaperonin groES protein (groES) and adenylosuccinate synthetase (ASS). No epitopes were detectable from known virulence factors. CD4+ T cell responsiveness in healthy adults against peptide pools representing epitope regions or full proteins confirmed the immunogenicity of PAL, PPP, groES, and ASS. Elevated lymphoproliferative activity to PPP, groES, and ASS in subjects within a year after the diagnosis of symptomatic pertussis suggested immunogenic exposure to these proteins during clinical infection. The PAL-, PPP-, groES-, and ASS-specific responses were associated with secretion of functional Th1 (tumor necrosis factor alpha [TNF-α] and gamma interferon [IFN-γ]) and Th2 (interleukin 5 [IL-5] and IL-13) cytokines. Relative paucity in the natural B. pertussis epitope display of MDDC, not dominated by epitopes from known protective antigens, can interfere with the effectiveness of immune recognition of B. pertussis. A more complete understanding of hallmarks in B. pertussis-specific immunity may advance the design of novel immunological assays and prevention strategies. PMID:24599530

  10. Bordetella pertussis proteins dominating the major histocompatibility complex class II-presented epitope repertoire in human monocyte-derived dendritic cells.

    PubMed

    Stenger, Rachel M; Meiring, Hugo D; Kuipers, Betsy; Poelen, Martien; van Gaans-van den Brink, Jacqueline A M; Boog, Claire J P; de Jong, Ad P J M; van Els, Cécile A C M

    2014-05-01

    Knowledge of naturally processed Bordetella pertussis-specific T cell epitopes may help to increase our understanding of the basis of cell-mediated immune mechanisms to control this reemerging pathogen. Here, we elucidate for the first time the dominant major histocompatibility complex (MHC) class II-presented B. pertussis CD4(+) T cell epitopes, expressed on human monocyte-derived dendritic cells (MDDC) after the processing of whole bacterial cells by use of a platform of immunoproteomics technology. Pertussis epitopes identified in the context of HLA-DR molecules were derived from two envelope proteins, i.e., putative periplasmic protein (PPP) and putative peptidoglycan-associated lipoprotein (PAL), and from two cytosolic proteins, i.e., 10-kDa chaperonin groES protein (groES) and adenylosuccinate synthetase (ASS). No epitopes were detectable from known virulence factors. CD4(+) T cell responsiveness in healthy adults against peptide pools representing epitope regions or full proteins confirmed the immunogenicity of PAL, PPP, groES, and ASS. Elevated lymphoproliferative activity to PPP, groES, and ASS in subjects within a year after the diagnosis of symptomatic pertussis suggested immunogenic exposure to these proteins during clinical infection. The PAL-, PPP-, groES-, and ASS-specific responses were associated with secretion of functional Th1 (tumor necrosis factor alpha [TNF-α] and gamma interferon [IFN-γ]) and Th2 (interleukin 5 [IL-5] and IL-13) cytokines. Relative paucity in the natural B. pertussis epitope display of MDDC, not dominated by epitopes from known protective antigens, can interfere with the effectiveness of immune recognition of B. pertussis. A more complete understanding of hallmarks in B. pertussis-specific immunity may advance the design of novel immunological assays and prevention strategies. PMID:24599530