Science.gov

Sample records for complex class i-related

  1. Emerging Major Histocompatibility Complex Class I-Related Functions of NLRC5.

    PubMed

    Chelbi, S T; Dang, A T; Guarda, G

    2017-01-01

    Recent evidence demonstrates a key role for the nucleotide-binding oligomerization domain-like receptor (NLR) family member NLRC5 (NLR family, CARD domain containing protein 5) in the transcriptional regulation of major histocompatibility complex (MHC) class I and related genes. Detailed information on NLRC5 target genes in various cell types and conditions is emerging. Thanks to its analogy to CIITA (class II major MHC transactivator), a NLR family member known for over 20 years to be the master regulator of MHC class II gene transcription, also the molecular mechanisms underlying NLRC5 function are being rapidly unraveled. MHC class I molecules are crucial in regulating innate and adaptive cytotoxic responses. Whereas CD8(+) T cells detect antigens presented on MHC class I molecules by infected or transformed cells, natural killer (NK) lymphocytes eliminate target cells with downregulated MHC class I expression. Data uncovering the relevance of NLRC5 in homeostasis and activity of these two lymphocyte subsets have been recently reported. Given the importance of CD8(+) T and NK cells in controlling infection and cancer, it is not surprising that NLRC5 is also starting to emerge as a central player in these diseases. This chapter summarizes and discusses novel insights into the molecular mechanisms underlying NLRC5 activity and its relevance to pathological conditions. A thorough understanding of both aspects is essential to evaluate the clinical significance and therapeutic potential of NLRC5.

  2. The Effect of Photodynamic Therapy on Tumor Cell Expression of Major Histocompatibility Complex (MHC) Class I and MHC Class I-Related Molecules

    PubMed Central

    Belicha-Villanueva, Alan; Riddell, Jonah; Bangia, Naveen; Gollnick, Sandra O.

    2013-01-01

    Background and Objective Photodynamic therapy (PDT) is FDA-approved anti-cancer modality for elimination of early disease and palliation in advanced disease. PDT efficacy depends in part on elicitation of a tumor-specific immune response that is dependent on cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. The cytolytic potential of CTLs and NK cells is mediated by the ability of these cells to recognize major histocompatibility complex (MHC) class I and MHC class I-related molecules. The MHC class I-related molecules MICA and MICB are induced by oxidative stress and have been reported to activate NK cells and co-stimulate CD8+ T cells. The purpose of this study was to examine the effect of PDT on tumor cell expression of MHC classes I and II-related molecules in vivo and in vitro. Study Design/Materials and Methods Human colon carcinoma Colo205 cells and murine CT26 tumors were treated with 2-[1-hexyloxyethyl]-2-devinyl pyropheophor-bide-a (HPPH)-PDT at various doses. MHC classes I and I-related molecule expression following treatment of Colo205 cells was temporally examined by flow cytometry using antibodies specific for components of MHC class I molecules and by quantitative PCR using specific primers. Expression of MHC class I-related molecules following HPPH-based PDT (HPPH-PDT) of murine tumors was monitored using a chimeric NKG2D receptor. Results In vitro HPPH-PDT significantly induces MICA in Colo205 cells, but had no effect on MHC class I molecule expression. PDT also induced expression of NKG2D ligands (NKG2DL) following in vivo HPPH-PDT of a murine tumor. Induction of MICA corresponded to increased NK killing of PDT-treated tumor cells. Conclusions PDT induction of MICA on human tumor cells and increased expression of NKG2DL by murine tumors following PDT may play a role in PDT induction of anti-tumor immunity. This conclusion is supported by our results demonstrating that tumor cells have increased sensitivity to NK cell lysis following

  3. Membrane-bound versus soluble major histocompatibility complex Class I-related chain A and major histocompatibility complex Class I-related chain B differential expression: Mechanisms of tumor eradication versus evasion and current drug development strategies.

    PubMed

    Suresh, P K

    2016-01-01

    Major histocompatibility complex Class I-related chain A/chain B (MICA/MICB) is stress-inducible, highly polymorphic ligands whose expression at the transcript level has been detected in all tissues except the central nervous system. However, their restricted protein expression is due to their regulation at the posttranslational level. Its levels are elevated in virally infected and neoplastically transformed cells. Membrane expression of this NKG2DL marks the aberrant cells for elimination by those immune effector cells that express the cognate NKG2D receptor. Among the evasion strategies developed by tumors, the metalloprotease-dependent shedding of MICA/MICB from tumors (either the free or the exosome form) can contribute to the inhibition of cytolysis by the immune effector cells (all NK cells, most NKT cells; γδ CD8+ T cells and αβ CD8+ T cells, as well as some αβ CD4+ T cells). There are micro-RNA clusters that regulate surface expression and shedding. Polymorphic variants can be used as susceptibility/associative markers and can also possibly be used to correlate with tumor survival as well as staging/grading of tumors. Variations in the expression level require quantification of this marker for diagnostic/prognostic and therapeutic purposes. Mechanism-based studies would provide a better tumor-specific understanding of their relative roles in the processes of tumor cell elimination versus growth and progression. Last but not least, conventional, interlaboratory validated assays (for, e.g., antibody-based methods) should be replaced by robust, reproducible, feasible biophysics-based methods using tumor biopsies. Further, correlative DNA polymorphism-based studies can be done using biological fluids (for, e.g., human saliva) that can be sampled by minimally invasive means.

  4. Full-length coding sequences of three major histocompatibility complex class I-related chain A alleles, MICA*019, MICA*027 and MICA*045, identified by sequence-based typing in Chinese individuals.

    PubMed

    Xu, Y P; Gao, S Q; Tao, H

    2015-10-01

    Full-length coding sequences of three major histocompatibility complex class I-related chain A alleles, MICA*019, MICA*027 and MICA*045. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. 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

  6. 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).

  7. Expression and clinical value of the soluble major histocompatibility complex class I-related chain A molecule in the serum of patients with renal tumors.

    PubMed

    Zhao, Y-K; Jia, C-M; Yuan, G-J; Liu, W; Qiu, Y; Zhu, Q-G

    2015-06-29

    We investigated the expression and clinical value of the soluble major histocompatibility complex class I-related chain A (sMICA) molecule in the serum of patients with renal tumors. Sixty patients diagnosed with renal tumors were enrolled in the experimental group, whereas 20 healthy volunteers served as the control group. The sMICA levels were measured via enzyme-linked immunosorbent assay, and the results were analyzed in combination with data from pathol-ogy examination. The experimental group had a statistically significant higher sMICA level (P < 0.05) than the control group. The sMICA level was higher in patients with malignant tumors than in those with be-nign tumors. We also observed a positive relationship among different tumor-node-metastasis (TNM) pathological stages with more advanced diseases exhibiting higher sMICA levels. As a tumor-associated antigen, MICA has a close relationship with renal tumorigenesis and immune es-cape. Our results indicated that sMICA levels were related to tumor pathol-ogy, TNM stage, and metastasis. Therefore, sMICA might be a potential marker for tumor characteristics, prognosis, and recurrence prediction.

  8. Cutting Edge: Down-regulation of major histocompatibility complex class I-related chain A (MICA) on tumor cells by IFNγ-induced microRNA1

    PubMed Central

    Yadav, Deepak; Ngolab, Jennifer; Seung-Hwan Lim, Rod; Krishnamurthy, Siddharth; Bui, Jack D.

    2009-01-01

    NKG2D is a receptor used by natural killer (NK) cells to detect virally infected and transformed cells. It recognizes ligands that are expressed constitutively on primary tumors and tumor cell lines. In this report, we have identified four microRNAs (miRNAs) that each was sufficient to reduce the expression of the NKG2D ligand major histocompatibility complex class I-related chain A (MICA). One of these miRNAs (miR-520b) was induced by IFNγ, leading to a reduction in MICA surface protein levels. Interestingly, miR-520b acted on both the MICA 3′UTR and promoter region and caused a decrease in the levels of MICA transcript. In contrast, an anti-sense oligonucleotide inhibitor of miR-520b increased the expression of a reporter construct containing the MICA 3′UTR but not the MICA promoter region. These findings demonstrate the novel regulation of an NKG2D ligand by an endogenous miRNA that is itself induced by IFNγ. PMID:19109132

  9. Serum soluble major histocompatibility complex class I-related chain A/B expression in patients with alcoholic liver disease in Hainan Li community

    PubMed Central

    Wei, Xiaobin; Ren, Biqiong; Lin, Danqin; Luo, Bin; Fu, Xianxian; Li, Chunyun; Xia, Huan; Xiao, Xi; Yu, Ping

    2015-01-01

    Background/Aims: To study the expression and clinical significance of serum soluble major histocompatibility complex class I-related chain A/B (sMICA/B), and its correlation with percentage of CD4+, CD8+, and NK cells, Liver fibrosis screening test, and liver enzymes in alcoholic liver disease (ALD). Methods: Hainan Li ALD patients (n = 141) and healthy Li subjects (n = 100) were enrolled for the study. Liver enzymes were measured using automatic biochemical analyzer and Liver fibrosis screening test was used to study the correlation. In addition, sMICA/B expression in serum and percentage of CD4+, CD8+, and NK cells were determined using ELISA and flow cytometry respectively. Results: Liver fibrosis screening test results and liver enzymes concentration were significantly higher (both P < 0.01), whereas the expression of sMICA and sMICB was significantly indifferent (P > 0.01) between ALD patients and healthy controls. However, percentage of CD4+, CD8+, and NK cells were statistically lower in ALD patients than in healthy controls. The Kendall’s tau-b correlation coefficient for sMICA and sMICB/sMICA and LV was 0.561 and 0.120 respectively (P < 0.01). Pearson correlation coefficient of sMICA with the percentage of CD4+, CD8+%, and NK cells was -0.587, -0.525, and -0.232 respectively, whereas the coefficient of sMICB was -0.590, -0.554, and -0.292 respectively (P < 0.01). Conclusion: 1. Liver fibrosis screening test is an excellent non-invasive approach for the diagnosis of hepatic fibrosis and shows significant correlation with liver enzymes. 2. sMICA and sMICB failed to assess the degree of hepatic fibrosis. 3. Decreased percentage of CD4+, CD8+, and NK cells were attributed as one of the risk factors for ALD. PMID:26550349

  10. Soluble Major Histocompatibility Complex Class I-Related Chain B Molecules Are Increased and Correlate With Clinical Outcomes During Rhinovirus Infection in Healthy Subjects

    PubMed Central

    Telcian, Aurica G.; Caramori, Gaetano; Laza-Stanca, Vasile; Message, Simon D.; Kebadze, Tatiana; Kon, Onn M.; Groh, Veronika; Papi, Alberto; Johnston, Sebastian L.; Mallia, Patrick; Stanciu, Luminita A.

    2014-01-01

    BACKGROUND: Surface major histocompatibility complex class I-related chain (MIC) A and B molecules are increased by IL-15 and have a role in the activation of natural killer group 2 member D-positive natural killer and CD8 T cells. MICA and MICB also exist in soluble forms (sMICA and sMICB). Rhinoviruses (RVs) are the major cause of asthma exacerbations, and IL-15 levels are decreased in the airways of subjects with asthma. The role of MIC molecules in immune responses in the lung has not been studied. Here, we determine the relationship between MICA and MICB and RV infection in vitro in respiratory epithelial cells and in vivo in healthy subjects and subjects with asthma. METHODS: Surface MICA and MICB, as well as sMICA and sMICB, in respiratory epithelial cells were measured in vitro in response to RV infection and exposure to IL-15. Levels of sMICA and sMICB in serum, sputum, and BAL were measured and correlated with blood and bronchoalveolar immune cells in healthy subjects and subjects with asthma before and during RV infection. RESULTS: RV increased MICA and MICB in vitro in epithelial cells. Exogenous IL-15 upregulated sMICB levels in RV-infected epithelial cells. Levels of sMICB molecules in serum were increased in healthy subjects compared with subjects with stable asthma. Following RV infection, airway levels of sMIC are upregulated, and there are positive correlations between sputum MICB levels and the percentage of bronchoalveolar natural killer cells in healthy subjects but not subjects with asthma. CONCLUSIONS: RV infection induces MIC molecules in respiratory epithelial cells in vitro and in vivo. Induction of MICB molecules is impaired in subjects with asthma, suggesting these molecules may have a role in the antiviral immune response to RV infections. PMID:24556715

  11. Major histocompatibility complex class I-related chain A/B (MICA/B) expression in tumor tissue and serum of pancreatic cancer: role of uric acid accumulation in gemcitabine-induced MICA/B expression.

    PubMed

    Xu, Xiulong; Rao, Geetha S; Groh, Veronika; Spies, Thomas; Gattuso, Paolo; Kaufman, Howard L; Plate, Janet; Prinz, Richard A

    2011-05-23

    Major histocompatibility complex class I-related chain A and B (MICA/B) are two stress-inducible ligands that bind the immunoreceptor NKG2D and play an important role in mediating the cyotoxicity of NK and T cells. In this study, we sought to study MICA/B expression in pancreatic cancer and to determine whether and how genotoxic drugs such as gemcitabine can affect MICA/B expression and natural killer cytotoxity. Seven pancreatic cancer cell lines were analyzed for MICA/B expression by flow cytometry and for their sensitivity to NK-92 cell killing by a 51Cr release assay. MICA/B expression in tumor tissues and sera of pancreatic cancer was analyzed by immunohistochemical staining (IHC) and ELISA, respectively. Two MICA/B-positive cell lines were sensitive to the cytotoxic activity of NK-92 cells. Other two MICA/B-positive cell lines and three MICA/B-negative cell lines were resistant to NK-92 cell killing. MICA/B expression was positive in 17 of 25 (68%) pancreatic ductal adenocarcinomas but not in normal pancreatic ductal epithelial cells. Serum MICA/B levels were significantly elevated in patients with pancreatic adenocarcinomas but did not correlate with the stage of pancreatic cancer and patient survival. Gemcitabine therapy led to increased serum MICA levels in 6 of 10 patients with detectable serum MICA. Allopurinol, an inhibitor of xanthine oxidoreductase that converts xanthine to uric acid, blocked uric acid production, MICA/B expression, and sensitivity to NK-92 cell killing toward a PANC-1 cancer cell line exposed to radiation and two genotoxic drugs, gemcitabine and 5-fluorouracil. The levels of MICA/B expression in serum and tissue of pancreatic cancer are elevated. DNA damage-induced MICA/B expression is mediated through increased uric acid production.

  12. Augmented serum level of major histocompatibility complex class I-related chain A (MICA) protein and reduced NKG2D expression on NK and T cells in patients with cervical cancer and precursor lesions.

    PubMed

    Arreygue-Garcia, Naela A; Daneri-Navarro, Adrian; del Toro-Arreola, Alicia; Cid-Arregui, Angel; Gonzalez-Ramella, Oscar; Jave-Suarez, Luis F; Aguilar-Lemarroy, Adriana; Troyo-Sanroman, Rogelio; Bravo-Cuellar, Alejandro; Delgado-Rizo, Vidal; Garcia-Iglesias, Trinidad; Hernandez-Flores, Georgina; Del Toro-Arreola, Susana

    2008-01-21

    Cervical cancer is the second most common cancer in women worldwide. NK and cytotoxic T cells play an important role in the elimination of virus-infected and tumor cells through NKG2D activating receptors, which can promote the lysis of target cells by binding to the major histocompatibility complex class I-related chain A (MICA) proteins. Increased serum levels of MICA have been found in patients with epithelial tumors. The aim of this study was to compare the levels of soluble MICA (sMICA) and NKG2D-expressing NK and T cells in blood samples from patients with cervical cancer or precursor lesions with those from healthy donors. Peripheral blood with or without heparin was collected to obtain mononuclear cells or sera, respectively. Serum sMICA levels were measured by ELISA and NKG2D-expressing immune cells were analyzed by flow cytometry. Also, a correlation analysis was performed to associate sMICA levels with either NKG2D expression or with the stage of the lesion. Significant amounts of sMICA were detected in sera from nearly all patients. We found a decrease in the number of NKG2D-expressing NK and T cells in both cervical cancer and lesion groups when compared to healthy donors. Pearson analysis showed a negative correlation between sMICA and NKG2D-expressing T cells; however, we did not find a significant correlation when the analysis was applied to sMICA and NKG2D expression on NK cells. Our results show for the first time that high sMICA levels are found in sera from patients with both cervical cancer and precursor lesions when compared with healthy donors. We also observed a diminution in the number of NKG2D-expressing NK and T cells in the patient samples; however, a significant negative correlation between sMICA and NKG2D expression was only seen in T cells.

  13. Universality classes of complexity

    NASA Astrophysics Data System (ADS)

    Saakian, David B.

    We give several criteria of complexity and define different universality classes. According to our classification, at the lowest class of complexity are random graph, Markov Models and Hidden Markov Models. At the next level is Sherrington-Kirkpatrick spin glass, connected with neuron-network models. On a higher level are critical theories, spin glass phase of Random Energy Model, percolation, self organized criticality (SOC). The top level class involves HOT design, error threshold in optimal coding, language, and, maybe, financial market. Alive systems are also related with the last class.

  14. 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. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. MHC Class I-Related Antigen-Processing Machinery Component Defects in Feline Mammary Carcinoma1

    PubMed Central

    Favole, Alessandra; Cascio, Paolo; Cerruti, Fulvia; Sereno, Alessandra; Tursi, Massimiliano; Tomatis, Alessandro; Beffa, Cristina Della; Ferrone, Soldano; Bollo, Enrico

    2012-01-01

    Defects in HLA class I antigen-processing machinery (APM) component expression and/or function are frequent in human tumors. These defects may provide tumor cells with a mechanism to escape from recognition and destruction by HLA class I antigen-restricted, tumor antigen-specific cytotoxic T cells. However, expression and functional properties of MHC class I antigens and APM components in malignant cells in other animal species have been investigated to a limited extent. However, this information can contribute to our understanding of the mechanisms underlying the association of MHC class I antigen and APM component defects with malignant transformation of cells and to identify animal models to validate targeted therapies to correct these defects. To overcome this limitation in the present study, we have investigated the expression of the catalytic subunits of proteasome (Y, X, and Z) and of immunoproteasome (LMP2, LMP7, and LMP10) as well as of MHC class I heavy chain (HC) in 25 primary feline mammary carcinomas (FMCs) and in 23 matched healthy mammary tissues. We found a reduced expression of MHC class I HC and of LMP2 and LMP7 in tumors compared with normal tissues. Concordantly, proteasomal cleavage specificities in extracts from FMCs were different from those in healthy tissues. In addition, correlation analysis showed that LMP2 and LMP7 were concordantly expressed in FMCs, and their expression was significantly correlated with that of MHC class I HC. The abnormalities we have found in the APM in FMCs may cause a defective processing of some tumor antigens. PMID:22348176

  17. A cluster of ten novel MHC class I related genes on human chromosome 6q24.2-q25.3.

    PubMed

    Radosavljevic, Mirjana; Cuillerier, Benoît; Wilson, Michael J; Clément, Oliver; Wicker, Sophie; Gilfillan, Susan; Beck, Stephan; Trowsdale, John; Bahram, Seiamak

    2002-01-01

    We have identified a novel family of human major histocompatibility complex (MHC) class I genes. This MHC class I related gene family is defined by 10 members, among which 6 encode potentially functional glycoproteins. The 180-kb cluster containing them has been generated by serial duplication and minimal diversification of an ancestral prototype. They are not located within the MHC on 6p21.3, but near the tip of its long arm at q24.2-q25.3, close to the human equivalent of the mouse H2-linked t-complex, a subchromosomal region syntenic to a segment of mouse chromosome 10 harboring the orthologous MHC class I related retinoic acid early transcript loci, Raet1a-d. Hence we have named the identified loci RAET1E-N. Human RAET1 products are all devoid of the membrane-proximal immunoglobulin-like alpha3 domain and most, but not all, are predicted to remain membrane-anchored via glycosylphosphatidylinositol linkage and are shown to display an atypical pattern of polymorphism. RAET1 transcripts are absent from hematopoietic tissues, but largely expressed in tumors. The involvement of orthologous mouse RAET1A-D/H60 in natural killer and T-cell activation through NKG2D engagement augurs a similar function for the human RAET1 proteins.

  18. Cell surface expression of MR1B, a splice variant of the MHC class I-related molecule MR1, revealed with antibodies.

    PubMed

    Yamaguchi, Hisateru; Tsukamoto, Kentaro; Hashimoto, Keiichiro

    2014-01-10

    The major histocompatibility complex (MHC) class I-related molecule, MR1, is highly conserved in mammals and can present bacteria-derived vitamin B metabolites to mucosal-associated invariant T (MAIT) cells, possibly having important defense function in the microbial infection. MR1B is a splice variant of MR1 and possesses an intriguing domain structure with only two extracellular domains resembling some NKG2D ligand molecules. Thus far, cell surface expression of MR1B could not be analyzed with flow cytometry due to a lack of appropriate antibodies reactive with MR1B. Here we clarified the expression of MR1B recombinant protein on the cell surface of the transfected cells by flow cytometry analyses using the antiserum against MR1. Consistently, MR1B tagged with FLAG peptide at the N-terminus also could be detected with anti-FLAG monoclonal antibodies. Our result showed that MR1B can be recognized on the cell surface by macromolecules such as antibodies, indicating its potential of interaction with certain receptor(s). We discuss possibility of interaction of MR1B and/or the full-length MR1 with some receptor(s) other than αβ T cell receptor (TCR) of MAIT cells based on the highly conserved characteristic residues of the ligand-binding domains of MR1 and its MAIT cells αβTCR footprints.

  19. MHC class I-related chain A and B ligands are differentially expressed in human cervical cancer cell lines

    PubMed Central

    2011-01-01

    Background Natural killer (NK) cells are an important resource of the innate immune system directly involved in the spontaneous recognition and lysis of virus-infected and tumor cells. An exquisite balance of inhibitory and activating receptors tightly controls the NK cell activity. At present, one of the best-characterized activating receptors is NKG2D, which promotes the NK-mediated lysis of target cells by binding to a family of cell surface ligands encoded by the MHC class I chain-related (MIC) genes, among others. The goal of this study was to describe the expression pattern of MICA and MICB at the molecular and cellular levels in human cervical cancer cell lines infected or not with human papillomavirus, as well as in a non-tumorigenic keratinocyte cell line. Results Here we show that MICA and MICB exhibit differential expression patterns among HPV-infected (SiHa and HeLa) and non-infected cell lines (C33-A, a tumor cell line, and HaCaT, an immortalized keratinocyte cell line). Cell surface expression of MICA was higher than cell surface expression of MICB in the HPV-positive cell lines; in contrast, HPV-negative cells expressed lower levels of MICA. Interestingly, the MICA levels observed in C33-A cells were overcome by significantly higher MICB expression. Also, all cell lines released higher amounts of soluble MICB than of soluble MICA into the cell culture supernatant, although this was most pronounced in C33-A cells. Additionally, Real-Time PCR analysis demonstrated that MICA was strongly upregulated after genotoxic stress. Conclusions This study provides evidence that even when MICA and MICB share a high degree of homology at both genomic and protein levels, differential regulation of their expression and cell surface appearance might be occurring in cervical cancer-derived cells. PMID:21631944

  20. Topological structural classes of complex networks

    NASA Astrophysics Data System (ADS)

    Estrada, Ernesto

    2007-01-01

    We use theoretical principles to study how complex networks are topologically organized at large scale. Using spectral graph theory we predict the existence of four different topological structural classes of networks. These classes correspond, respectively, to highly homogenous networks lacking structural bottlenecks, networks organized into highly interconnected modules with low inter-community connectivity, networks with a highly connected central core surrounded by a sparser periphery, and networks displaying a combination of highly connected groups (quasicliques) and groups of nodes partitioned into disjoint subsets (quasibipartites). Here we show by means of the spectral scaling method that these classes really exist in real-world ecological, biological, informational, technological, and social networks. We show that neither of three network growth mechanisms—random with uniform distribution, preferential attachment, and random with the same degree sequence as real network—is able to reproduce the four structural classes of complex networks. These models reproduce two of the network classes as a function of the average degree but completely fail in reproducing the other two classes of networks.

  1. Regulation of the expression of MHC class I-related chain A, B (MICA, MICB) via chromatin remodeling and its impact on the susceptibility of leukemic cells to the cytotoxicity of NKG2D-expressing cells.

    PubMed

    Kato, N; Tanaka, J; Sugita, J; Toubai, T; Miura, Y; Ibata, M; Syono, Y; Ota, S; Kondo, T; Asaka, M; Imamura, M

    2007-10-01

    Innate immune cells such as natural killer (NK) cells play a crucial role in antitumor immune responses. NKG2D is a major activating immunoreceptor expressed in not only NK cells but also CD8+ T cells and shows cytotoxicity against tumors by recognizing its ligands major histocompatibility complex class I-related chain A and B (MICA and MICB) on tumor cells. Recently, it has been suggested that NKG2D-mediated cytotoxicity correlates with the expression levels of NKG2D ligands on target cells. In this study, we were able to increase the expression levels of MICA and MICB on leukemic cell lines and patients' leukemic cells by treatment with trichostatin A (TsA), a histone deacetylase (HDAC) inhibitor. Chromatin immunoprecipitation (ChIP) assays revealed that treatment with TsA resulted in increased acetylation of histone H3 and decreased association with HDAC1 at the promoters of MICA and MICB. Intriguingly, upregulation of MICA and MICB by treatment with TsA led to enhancement of the susceptibility of leukemic cells to the cytotoxicity of NKG2D-expressing cells. Our results suggest that regulation of the expression of NKG2D ligands by treatment with chromatin-remodeling drugs may be an attractive strategy for immunotherapy.

  2. COMPLEX STRUCTURE IN CLASS 0 PROTOSTELLAR ENVELOPES

    SciTech Connect

    Tobin, John J.; Hartmann, Lee; Looney, Leslie W.; Chiang, Hsin-Fang

    2010-04-01

    We use archived Infrared Array Camera images from the Spitzer Space Telescope to show that many Class 0 protostars exhibit complex, irregular, and non-axisymmetric structure within their dusty envelopes. Our 8 {mu}m extinction maps probe some of the densest regions in these protostellar envelopes. Many of the systems are observed to have highly irregular and non-axisymmetric morphologies on scales {approx}>1000 AU, with a quarter of the sample exhibiting filamentary or flattened dense structures. Complex envelope structure is observed in regions spatially distinct from outflow cavities, and the densest structures often show no systematic alignment perpendicular to the cavities. These results indicate that mass ejection is not responsible for much of the irregular morphologies we detect; rather, we suggest that the observed envelope complexity is mostly the result of collapse from protostellar cores with initially non-equilibrium structures. The striking non-axisymmetry in many envelopes could provide favorable conditions for the formation of binary systems. We also note that protostars in the sample appear to be formed preferentially near the edges of clouds or bends in filaments, suggesting formation by gravitational focusing.

  3. Correlation of major histocompatibility complex class I related A (MICA) polymorphism with the risk of developing breast cancer.

    PubMed

    Vallian, Sadeq; Rad, Morteza Javadi; Tavallaei, Mahmood; Tavassoli, Manoochehr

    2012-03-01

    In the present study, we examined the association of different alleles of MICA gene with the risk of breast cancer development in Iranian population. Our data showed a significant relationship between longer alleles, alleles with 9- and 6-GCT repeat of MICA gene, and a higher risk of developing breast cancer according to the age of onset. The data indicated a 6-fold increase for developing breast cancer in patients carrying the allele with 6-GCT repeat after age 50 (OR = 5.8333, 95% CI: 1.2976-26/2236, P = 0.0172). In addition, patients carrying longer alleles in their genotype (6/6, 6/9, and 9/9 genotypes) were found significantly at higher risk of developing breast cancer than control individuals (OR = 5.6, P = 0.0038, 95% CI: 1.6578-18.9166). In contrast, alleles with short GCT repeat of 4 and 5.1 showed to play a role in reducing the risk of breast cancer (OR = 0.79, P = 0.3643 and 95% CI: 0.4743-1.3157). Women with allele 4 were found twofold more protected against breast cancer (OR = 0.4597, 95% CI: 0.2164-0.9765, P = 0.0401). The results suggested that women with genotypes with 9- and 6-GCT repeat alleles of MICA gene could be considered more potent to develop breast cancer especially at higher age.

  4. A study on the polymorphism of human MHC class I-related MR1 gene and identification of an MR1-like pseudogene.

    PubMed

    Parra-Cuadrado, J F; Navarro, P; Mirones, I; Setién, F; Oteo, M; Martínez-Naves, E

    2000-08-01

    Human MR1 is a recently discovered, ubiquitously transcribed gene very similar to the HLA class I loci and of unknown function. Mouse and rat MR1 sequences have also been described showing high similarity with the human gene. The goal of this work was to investigate if human MR1 was polymorphic. We have found that DNA sequences of MR1-specific polymerase chain reaction (PCR) products obtained from samples of diverse ethnic origin were invariant except in one case in which two silent mutations were detected. We also found an MR1-like sequence displaying significant differences with the previously described, the most remarkable of which is a STOP codon in the alpha2 domain indicating that is a pseudogene.

  5. Expression of major histocompatibility complex class I and class II antigens in canine masticatory muscle myositis.

    PubMed

    Paciello, Orlando; Shelton, G Diane; Papparella, Serenella

    2007-04-01

    Studies in human immune-mediated inflammatory myopathies have documented expression of major histocompatibility complex class I (MHC class I) and class II (MHC class II) antigens on muscle fiber membranes in the presence or absence of cellular infiltration. Here we evaluate the presence and distribution of these antigens in canine masticatory muscle myositis, an immune-mediated inflammatory myopathy. Twelve samples of temporalis and masseter muscles from dogs with a clinical diagnosis of canine masticatory muscle myositis were examined by immunohistochemistry and double-immunofluorescence confocal microscopy. MHC class I and class II antigens were expressed in muscle fibers independent of inflammatory cell infiltration. Furthermore MHC class I and class II antigens were expressed on the sarcolemma and co-localized with dystrophin. Our results suggest that MHC class I and class II expression in canine masticatory muscle myositis may play a role in the initiation and maintenance of the pathological condition, rather than just a consequence of a preceding local inflammation.

  6. Nonlinkage of major histocompatibility complex class I and class II loci in bony fishes.

    PubMed

    Sato, A; Figueroa, F; Murray, B W; Málaga-Trillo, E; Zaleska-Rutczynska, Z; Sültmann, H; Toyosawa, S; Wedekind, C; Steck, N; Klein, J

    2000-02-01

    In tetrapods, the functional (classical) class I and class II B loci of the major histocompatibility complex (Mhc) are tightly linked in a single chromosomal region. In an earlier study, we demonstrated that in the zebrafish, Danio rerio, order Cypriniformes, the two classes are present on different chromosomes. Here, we show that the situation is similar in the stickleback, Gasterosteus aculeatus, order Gasterosteiformes, the common guppy, Poecilia reticulata, order Cyprinodontiformes, and the cichlid fish Oreochromis niloticus, order Perciformes. These data, together with unpublished results from other laboratories suggest that in all Euteleostei, the classical class I and class II B loci are in separate linkage groups, and that in at least some of these taxa, the class II loci are in two different groups. Since Euteleostei are at least as numerous as tetrapods, in approximately one-half of jawed vertebrates, the class I and class II regions are not linked.

  7. 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

  8. Liquid class predictor for liquid handling of complex mixtures

    SciTech Connect

    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.

  9. 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

  10. 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.

  11. Major Histocompatibility Complex (MHC) Class I and MHC Class II Proteins: Conformational Plasticity in Antigen Presentation

    PubMed Central

    Wieczorek, Marek; Abualrous, Esam T.; Sticht, Jana; Álvaro-Benito, Miguel; Stolzenberg, Sebastian; Noé, Frank; Freund, Christian

    2017-01-01

    Antigen presentation by major histocompatibility complex (MHC) proteins is essential for adaptive immunity. Prior to presentation, peptides need to be generated from proteins that are either produced by the cell’s own translational machinery or that are funneled into the endo-lysosomal vesicular system. The prolonged interaction between a T cell receptor and specific pMHC complexes, after an extensive search process in secondary lymphatic organs, eventually triggers T cells to proliferate and to mount a specific cellular immune response. Once processed, the peptide repertoire presented by MHC proteins largely depends on structural features of the binding groove of each particular MHC allelic variant. Additionally, two peptide editors—tapasin for class I and HLA-DM for class II—contribute to the shaping of the presented peptidome by favoring the binding of high-affinity antigens. Although there is a vast amount of biochemical and structural information, the mechanism of the catalyzed peptide exchange for MHC class I and class II proteins still remains controversial, and it is not well understood why certain MHC allelic variants are more susceptible to peptide editing than others. Recent studies predict a high impact of protein intermediate states on MHC allele-specific peptide presentation, which implies a profound influence of MHC dynamics on the phenomenon of immunodominance and the development of autoimmune diseases. Here, we review the recent literature that describe MHC class I and II dynamics from a theoretical and experimental point of view and we highlight the similarities between MHC class I and class II dynamics despite the distinct functions they fulfill in adaptive immunity. PMID:28367149

  12. Antigen-B Cell Receptor Complexes Associate with Intracellular major histocompatibility complex (MHC) Class II Molecules*

    PubMed Central

    Barroso, Margarida; Tucker, Heidi; Drake, Lisa; Nichol, Kathleen; Drake, James R.

    2015-01-01

    Antigen processing and MHC class II-restricted antigen presentation by antigen-presenting cells such as dendritic cells and B cells allows the activation of naïve CD4+ T cells and cognate interactions between B cells and effector CD4+ T cells, respectively. B cells are unique among class II-restricted antigen-presenting cells in that they have a clonally restricted antigen-specific receptor, the B cell receptor (BCR), which allows the cell to recognize and respond to trace amounts of foreign antigen present in a sea of self-antigens. Moreover, engagement of peptide-class II complexes formed via BCR-mediated processing of cognate antigen has been shown to result in a unique pattern of B cell activation. Using a combined biochemical and imaging/FRET approach, we establish that internalized antigen-BCR complexes associate with intracellular class II molecules. We demonstrate that the M1-paired MHC class II conformer, shown previously to be critical for CD4 T cell activation, is incorporated selectively into these complexes and loaded selectively with peptide derived from BCR-internalized cognate antigen. These results demonstrate that, in B cells, internalized antigen-BCR complexes associate with intracellular MHC class II molecules, potentially defining a site of class II peptide acquisition, and reveal a selective role for the M1-paired class II conformer in the presentation of cognate antigen. These findings provide key insights into the molecular mechanisms used by B cells to control the source of peptides charged onto class II molecules, allowing the immune system to mount an antibody response focused on BCR-reactive cognate antigen. PMID:26400081

  13. Major histocompatibility complex class I polymorphism in Asiatic lions.

    PubMed

    Sachdev, M; Sankaranarayanan, R; Reddanna, P; Thangaraj, K; Singh, L

    2005-07-01

    Asiatic lions (Panthera leo persica), whose only natural habitat in the world is the Gir forest sanctuary of Gujarat State in India, are highly endangered and are considered to be highly inbred with narrow genetic diversity. An objective assessment of genetic diversity in their immune loci will help in assessing their survivability and may provide vital clues in designing strategies for their scientific management and conservation. We analyzed the comparative sequence polymorphism at exon 2 and exon 3 of major histocompatibility complex (MHC) class I in three groups of lions, i.e. wild Asiatic (from Gir forest), captive-bred Asiatic (from zoological parks in India), and Afro-Asiatic hybrid groups (from zoological parks in India) through polymorphism chain reaction-assisted sequence-based typing. The two exons were amplified, cloned, sequenced, and analyzed for polymorphism at nucleotide and putative translated product level. The analysis revealed extensive sequence polymorphism not only between clones derived from different lions but also the clones derived from a single lion. Furthermore, the wild Asiatic lions of Gir forest exhibited abundant sequence polymorphism at MHC class I comparable with that of Afro-Asiatic hybrid lions and significantly higher than that of captive-bred Asiatic lions. We hypothesize that Asiatic lions of Gir forest are not highly inbred as thought earlier and they possess abundant sequence polymorphism at MHC class I loci. During this study, 52 new sequences of the multigene MHC class I family were also identified among Asiatic lions.

  14. Universality classes of fluctuation dynamics in hierarchical complex systems

    NASA Astrophysics Data System (ADS)

    Macêdo, A. M. S.; González, Iván R. Roa; Salazar, D. S. P.; Vasconcelos, G. L.

    2017-03-01

    A unified approach is proposed to describe the statistics of the short-time dynamics of multiscale complex systems. The probability density function of the relevant time series (signal) is represented as a statistical superposition of a large time-scale distribution weighted by the distribution of certain internal variables that characterize the slowly changing background. The dynamics of the background is formulated as a hierarchical stochastic model whose form is derived from simple physical constraints, which in turn restrict the dynamics to only two possible classes. The probability distributions of both the signal and the background have simple representations in terms of Meijer G functions. The two universality classes for the background dynamics manifest themselves in the signal distribution as two types of tails: power law and stretched exponential, respectively. A detailed analysis of empirical data from classical turbulence and financial markets shows excellent agreement with the theory.

  15. 454 sequencing reveals extreme complexity of the class II Major Histocompatibility Complex in the collared flycatcher

    PubMed Central

    2010-01-01

    Background Because of their functional significance, the Major Histocompatibility Complex (MHC) class I and II genes have been the subject of continuous interest in the fields of ecology, evolution and conservation. In some vertebrate groups MHC consists of multiple loci with similar alleles; therefore, the multiple loci must be genotyped simultaneously. In such complex systems, understanding of the evolutionary patterns and their causes has been limited due to challenges posed by genotyping. Results Here we used 454 amplicon sequencing to characterize MHC class IIB exon 2 variation in the collared flycatcher, an important organism in evolutionary and immuno-ecological studies. On the basis of over 152,000 sequencing reads we identified 194 putative alleles in 237 individuals. We found an extreme complexity of the MHC class IIB in the collared flycatchers, with our estimates pointing to the presence of at least nine expressed loci and a large, though difficult to estimate precisely, number of pseudogene loci. Many similar alleles occurred in the pseudogenes indicating either a series of recent duplications or extensive concerted evolution. The expressed alleles showed unambiguous signals of historical selection and the occurrence of apparent interlocus exchange of alleles. Placing the collared flycatcher's MHC sequences in the context of passerine diversity revealed transspecific MHC class II evolution within the Muscicapidae family. Conclusions 454 amplicon sequencing is an effective tool for advancing our understanding of the MHC class II structure and evolutionary patterns in Passeriformes. We found a highly dynamic pattern of evolution of MHC class IIB genes with strong signals of selection and pronounced sequence divergence in expressed genes, in contrast to the apparent sequence homogenization in pseudogenes. We show that next generation sequencing offers a universal, affordable method for the characterization and, in perspective, genotyping of MHC systems of

  16. Bidirectional selection between two classes in complex social networks.

    PubMed

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

    2014-12-19

    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.

  17. Interpretation of biphasic dissociation kinetics for isomeric class II major histocompatibility complex-peptide complexes

    PubMed Central

    Anderson, TG; McConnell, HM

    1999-01-01

    Antigenic peptides bound to class II major histocompatibility complex (MHC) proteins play a key role in the distinction between "self" and "nonself" by the cellular immune system. Although the formation and dissociation of these complexes are often thought of in terms of the simple mechanism MHC + P &rlharr; MHC-P, studies of MHC-peptide dissociation kinetics suggest that multiple interconverting forms of the bound MHC-peptide complex can be formed. However, the precise relationship between observed dissociation data and proposed multiple-complex mechanisms has not been systematically examined. Here we provide a mathematical analysis to fill this gap and attempt to clarify the kinetic behavior that is expected to result from the proposed mechanisms. We also examine multiple-complex dynamics that can be "hidden" in conventional experiments. Although we focus on MHC-peptide interactions, the analysis provided here is fully general and applies to any ligand-receptor system having two distinct bound states. PMID:10545347

  18. Low-dose gemcitabine induces major histocompatibility complex class I-related chain A/B expression and enhances an antitumor innate immune response in pancreatic cancer.

    PubMed

    Miyashita, Tomoharu; Miki, Kenji; Kamigaki, Takashi; Makino, Isamu; Nakagawara, Hisatoshi; Tajima, Hidehiro; Takamura, Hiroyuki; Kitagawa, Hirohisa; Fushida, Sachio; Ahmed, Ali K; Duncan, Mark D; Harmon, John W; Ohta, Tetsuo

    2017-02-01

    We investigated the effect of gemcitabine (GEM), a key drug for pancreatic cancer treatment, on the expression of cell surface MICA/B in pancreatic cancer cells and resulting cytotoxicity of γδ T cells. We assessed the effect of GEM on the upregulation of cell surface MICA/B expression by flow cytometry, utilizing six pancreatic cancer cell lines. MICA and CD16 expressions from resected pancreatic cancer patient specimens, which received neoadjuvant chemotherapy (NAC) with GEM, were analyzed by immunohistochemistry. GEM could increase MICA/B expression on cell surface in pancreatic cancer cell lines (in 2 of 6 cell lines). This effect was most effectively at concentration not affecting cell growth of GEM (0.001 μM), because MICA/B negative population was appeared at concentration at cytostatic and cytotoxic effect to cell growth (0.1 and 10 μM). The cytotoxic activity of γδ T cells against PANC-1 was detected and functions through interactions between NKG2D and MICA/B. However, the enhancement of NKG2D-dependent cytotoxicity with increased MICA/B expression, by GEM treatment, was not observed. In addition, soluble MIC molecules were released from pancreatic cancer cell lines in culture supernatant with GEM treatment. Immunohistochemical staining demonstrated that MICA expression in tumor cells and CD16 positive cells surrounding tumors were significantly higher in the NAC group compared to that of the control group. There was a significant correlation between NAC and MICA expression, as well as NAC and CD16 positive cell expression. The present results indicate that low-dose GEM-induced MICA/B expression enhances innate immune function rather than cytotoxicity in pancreatic cancer. In addition, our result suggests that the inhibition of cleavage and release of MIC molecules from the tumor surface could potentially improve NKG2D-dependent cytotoxicity.

  19. 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.

  20. 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

  1. 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…

  2. Characterization of class I- and class II-like major histocompatibility complex loci in pedigrees of North Atlantic right whales.

    PubMed

    Gillett, Roxanne M; Murray, Brent W; White, Bradley N

    2014-01-01

    North Atlantic right whales have one of the lowest levels of genetic variation at minisatellite loci, microsatellite loci, and mitochondrial control region haplotypes among mammals. Here, adaptive variation at the peptide binding region of class I and class II DRB-like genes of the major histocompatibility complex was assessed. Amplification of a duplicated region in 222 individuals revealed at least 11 class II alleles. Six alleles were assigned to the locus Eugl-DRB1 and 5 alleles were assigned to the locus Eugl-DRB2 by assessing segregation patterns of alleles from 81 parent/offspring pedigrees. Pedigree analysis indicated that these alleles segregated into 12 distinct haplotypes. Genotyping a smaller subset of unrelated individuals (n = 5 and 10, respectively) using different primer sets revealed at least 2 class II pseudogenes (with ≥ 4 alleles) and at least 3 class I loci (with ≥ 6 alleles). Class II sequences were significantly different from neutrality at peptide binding sites suggesting loci may be under the influence of balancing selection. Trans-species sharing of alleles was apparent for class I and class II sequences. Characterization of class II loci represents the first step in determining the relationship between major histocompatibility complex variability and factors affecting health and reproduction in this species.

  3. Cytokine/Antibody complexes: an emerging class of immunostimulants.

    PubMed

    Mostböck, Sven

    2009-01-01

    In recent years, complexes formed from a cytokine and antibodies against that respective cytokine (cytokine/Ab complex) have been shown to induce remarkable powerful changes in the immune system. Strong interest exists especially for complexes formed with Interleukin (IL)-2 and anti-IL-2-antibody (IL-2/Ab complex). IL-2/Ab complex activates maturation and proliferation in CD8(+) T cells and natural killer (NK) cells to a much higher degree than conventional IL-2 therapy. In addition, IL-2/Ab complex does not stimulate regulatory T cells as much as IL-2 alone. This suggests the possibility to replace the conventional IL-2 therapy with a therapy using low-dose IL-2/Ab complex. Further synthetic cytokine/Ab complexes are studied currently, including IL-3/Ab complex for its effects on the mast cell population, and IL-4/Ab complex and IL-7/Ab complex for inducing B and T cell expansion and maturation. Cytokine complexes can also be made from a cytokine and its soluble receptor. Pre-association of IL-15 with soluble IL-15 receptor alpha produces a complex with strong agonistic functions that lead to an expansion of CD8(+) T cells and NK cells. However, cytokine/Ab complexes also occur naturally in humans. A multitude of auto-antibodies to cytokines are found in human sera, and many of these auto-antibodies build cytokine/Ab complexes. This review presents naturally occurring auto-antibodies to cytokines and cytokine/Ab complexes in health and disease. It further summarizes recent research on synthetic cytokine/Ab complexes with a focus on the basic mechanisms behind the function of cytokine/Ab complexes.

  4. β2-Glycoprotein I/HLA class II complexes are novel autoantigens in antiphospholipid syndrome

    PubMed Central

    Tanimura, Kenji; Jin, Hui; Suenaga, Tadahiro; Morikami, Satoko; Arase, Noriko; Kishida, Kazuki; Hirayasu, Kouyuki; Kohyama, Masako; Ebina, Yasuhiko; Yasuda, Shinsuke; Horita, Tetsuya; Takasugi, Kiyoshi; Ohmura, Koichiro; Yamamoto, Ken; Katayama, Ichiro; Sasazuki, Takehiko; Lanier, Lewis L.; Atsumi, Tatsuya; Yamada, Hideto

    2015-01-01

    Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis and/or pregnancy complications. β2-glycoprotein I (β2GPI) complexed with phospholipid is recognized as a major target for autoantibodies in APS; however, less than half the patients with clinical manifestations of APS possess autoantibodies against the complexes. Therefore, the range of autoantigens involved in APS remains unclear. Recently, we found that human leukocyte antigen (HLA) class II molecules transport misfolded cellular proteins to the cell surface via association with their peptide-binding grooves. Furthermore, immunoglobulin G heavy chain/HLA class II complexes were specific targets for autoantibodies in rheumatoid arthritis. Here, we demonstrate that intact β2GPI, not peptide, forms a complex with HLA class II molecules. Strikingly, 100 (83.3%) of the 120 APS patients analyzed, including those whose antiphospholipid antibody titers were within normal range, possessed autoantibodies that recognize β2GPI/HLA class II complexes in the absence of phospholipids. In situ association between β2GPI and HLA class II was observed in placental tissues of APS patients but not in healthy controls. Furthermore, autoantibodies against β2GPI/HLA class II complexes mediated complement-dependent cytotoxicity against cells expressing the complexes. These data suggest that β2GPI/HLA class II complexes are a target in APS that might be involved in the pathogenesis. PMID:25733579

  5. β2-Glycoprotein I/HLA class II complexes are novel autoantigens in antiphospholipid syndrome.

    PubMed

    Tanimura, Kenji; Jin, Hui; Suenaga, Tadahiro; Morikami, Satoko; Arase, Noriko; Kishida, Kazuki; Hirayasu, Kouyuki; Kohyama, Masako; Ebina, Yasuhiko; Yasuda, Shinsuke; Horita, Tetsuya; Takasugi, Kiyoshi; Ohmura, Koichiro; Yamamoto, Ken; Katayama, Ichiro; Sasazuki, Takehiko; Lanier, Lewis L; Atsumi, Tatsuya; Yamada, Hideto; Arase, Hisashi

    2015-04-30

    Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis and/or pregnancy complications. β2-glycoprotein I (β2GPI) complexed with phospholipid is recognized as a major target for autoantibodies in APS; however, less than half the patients with clinical manifestations of APS possess autoantibodies against the complexes. Therefore, the range of autoantigens involved in APS remains unclear. Recently, we found that human leukocyte antigen (HLA) class II molecules transport misfolded cellular proteins to the cell surface via association with their peptide-binding grooves. Furthermore, immunoglobulin G heavy chain/HLA class II complexes were specific targets for autoantibodies in rheumatoid arthritis. Here, we demonstrate that intact β2GPI, not peptide, forms a complex with HLA class II molecules. Strikingly, 100 (83.3%) of the 120 APS patients analyzed, including those whose antiphospholipid antibody titers were within normal range, possessed autoantibodies that recognize β2GPI/HLA class II complexes in the absence of phospholipids. In situ association between β2GPI and HLA class II was observed in placental tissues of APS patients but not in healthy controls. Furthermore, autoantibodies against β2GPI/HLA class II complexes mediated complement-dependent cytotoxicity against cells expressing the complexes. These data suggest that β2GPI/HLA class II complexes are a target in APS that might be involved in the pathogenesis.

  6. Specific suppression of major histocompatibility complex class I and class II genes in astrocytes by brain-enriched gangliosides

    PubMed Central

    1993-01-01

    The effect of brain-enriched gangliosides on constitutive and cytokine- inducible expression of major histocompatibility complex (MHC) class I and II genes in cultured astrocytes was studied. Before treatment with gangliosides, astrocytes expressed constitutive MHC class I but not class II molecules, however, the expression of both MHC class I and II cell surface molecules on astrocytes was induced to high levels by interferon gamma (IFN-gamma). Constitutive and IFN-gamma-inducible expression of MHC class I and II molecules was suppressed by treatment of astrocytes with exogenous bovine brain gangliosides in a dose- dependent manner. Constitutive and induced MHC class I and II mRNA levels were also suppressed by gangliosides, indicating control through transcriptional mechanisms. This was consistent with the ability of gangliosides to suppress the binding activity of transcription factors, especially NF-kappa B-like binding activity, important for the expression of both MHC class I and II genes. These studies may be important for understanding mechanisms of central nervous system (CNS)- specific regulation of major histocompatibility molecules in neuroectodermal cells and the role of gangliosides in regulating MHC- restricted antiviral and autoimmune responses within the CNS. PMID:8376939

  7. 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

  8. Wide complex tachycardia in the presence of class I antiarrhythmic agents: a diagnostic challenge.

    PubMed

    Bhardwaj, Bhaskar; Lazzara, Ralph; Stavrakis, Stavros

    2014-05-01

    We present two patients with paroxysmal atrial fibrillation on class 1C antiarrhythmic drugs without concomitant atrioventricular (AV) nodal blocking agents who developed atrial flutter with 1:1 AV conduction. Their electrocardiogram revealed wide complex tachycardia with rates >200/minute. Atrial flutter with 1:1 conduction in the presence of class IC antiarrhythmic drugs may present a diagnostic challenge. These cases illustrate the importance of coadministering an AV nodal blocking agent with class IC antiarrhythmic agents in patients with atrial fibrillation. The differential diagnosis of wide complex tachycardia in patients taking class IC agents should include atrial flutter with 1:1 AV conduction.

  9. Chicken major histocompatibility complex class I definition using antisera induced by cloned class I sequences.

    PubMed

    Fulton, J E; Hunt, H D; Bacon, L D

    2001-11-01

    Alloantisera directed against chicken class I MHC (BFIV) antigens were produced by using transfected cell lines expressing cloned BFIV sequences. The cloned BFIV sequences were from haplotypes *12, *13, and *21. Two laboratory-derived class I mutant sequences (BFIV13m126 and BFIV21m78) were developed to analyze cross-reactive epitopes and to induce specific alloantisera. Antisera were tested in hemagglutination and flow cytometry assays. The antisera produced were highly specific and had minimal cross-reactivity. The antisera induced by the BF1V21m78 mutant confirmed the significance of amino acids 78 and 81 in cross-reactivity between haplotypes B*21 and B*5. The highly specific antisera were tested by hemagglutination on red blood cells of 31 different MHC haplotypes. The consistency of hemagglutination patterns and minimal cross-reactivity demonstrated that these BFIV antisera are extremely valuable in defining MHC haplotype in various chicken lines. Because of the extreme low level of recombination between the chicken class I and class II loci, identification of BFIV allele can be used to define MHC haplotype within a line. Complete identity between the transfected cell line and the chicken used to produce the antiserum is required to ensure the monospecificity.

  10. Relationship between major histocompatibility complex class I expression and prognosis in canine mammary gland tumors.

    PubMed

    Tanaka, Toshiyuki; Shimada, Terumasa; Akiyoshi, Hideo; Shimizu, Junichiro; Zheng, Cao; Yijyun, Li; Mie, Keiichiro; Hayashi, Akiyoshi; Kuwamura, Mitsuru; Hoshi, Fumio; Ohashi, Fumihito

    2013-10-01

    The aim of this study was to evaluate MHC class I expression and prognosis using tumor tissues surgically removed from 9 dogs with mammary gland carcinomas and from 13 dogs with complex carcinomas. We assessed MHC class I expression and its correlation with tumor size, B2M expression, infiltration of lymphocytes, histological grade and prognosis. Hematoxylin and eosin-stained sections were histologically graded using the Elston and Ellis grading method. MHC class I expression on tumor cells was evaluated using the avidin-biotin peroxidase complex method. Loss of MHC class I expression from canine mammary gland carcinomas was significantly correlated with poor prognosis (P<0.05). Loss of MHC class I expression showed no association with poor prognosis in canine mammary gland complex carcinomas, because the data were not balanced. Only 1 of 13 (7.6%) canine mammary gland complex carcinomas showed loss of MHC class I expression. All 13 of these dogs showed good prognosis. Thus, the low frequency of MHC class I expression loss from canine mammary gland complex carcinomas may be associated with good prognosis. Taken together, these results suggest that loss of MHC class I expression may be associated with poor prognosis in canine mammary gland carcinomas.

  11. Human Herpesvirus 7 U21 Tetramerizes To Associate with Class I Major Histocompatibility Complex Molecules

    PubMed Central

    May, Nathan A.; Wang, Qiuhong; Balbo, Andrea; Konrad, Sheryl L.; Buchli, Rico; Hildebrand, William H.; Schuck, Peter

    2014-01-01

    ABSTRACT The U21 gene product from human herpesvirus 7 binds to and redirects class I major histocompatibility complex (MHC) molecules to a lysosomal compartment. The molecular mechanism by which U21 reroutes class I MHC molecules to lysosomes is not known. Here, we have reconstituted the interaction between purified soluble U21 and class I MHC molecules, suggesting that U21 does not require additional cellular proteins to interact with class I MHC molecules. Our results demonstrate that U21, itself predicted to contain an MHC class I-like protein fold, interacts tightly with class I MHC molecules as a tetramer, in a 4:2 stoichiometry. These observations have helped to elucidate a refined model describing the mechanism by which U21 escorts class I MHC molecules to the lysosomal compartment. IMPORTANCE In this report, we show that the human herpesvirus 7 (HHV-7) immunoevasin U21, itself a class I MHC-like protein, binds with high affinity to class I MHC molecules as a tetramer and escorts them to lysosomes, where they are degraded. While many class I MHC-like molecules have been described in detail, this unusual viral class I-like protein functions as a tetramer, associating with class I MHC molecules in a 4:2 ratio, illuminating a functional significance of homooligomerization of a class I MHC-like protein. PMID:24390327

  12. A Tale of Three Classes: Case Studies in Course Complexity

    ERIC Educational Resources Information Center

    Gill, T. Grandon; Jones, Joni

    2010-01-01

    This paper examines the question of decomposability versus complexity of teaching situations by presenting three case studies of MIS courses. Because all three courses were highly successful in their observed outcomes, the paper hypothesizes that if the attributes of effective course design are decomposable, one would expect to see a large number…

  13. A Tale of Three Classes: Case Studies in Course Complexity

    ERIC Educational Resources Information Center

    Gill, T. Grandon; Jones, Joni

    2010-01-01

    This paper examines the question of decomposability versus complexity of teaching situations by presenting three case studies of MIS courses. Because all three courses were highly successful in their observed outcomes, the paper hypothesizes that if the attributes of effective course design are decomposable, one would expect to see a large number…

  14. Defective Major Histocompatibility Complex Class I Expression in a Sarcomatoid Renal Cell Carcinoma Cell Line

    PubMed Central

    Jakobsen, Michael K.; Restifo, Nicholas P.; Cohen, Peter A.; Marincola, Francesco M.; Cheshire, L. Bryan; Linehan, W. Marston; Rosenberg, Steven A.; Alexander, Richard B.

    2008-01-01

    Summary We studied major histocompatibility complex (MHC) class I expression in 12 tumor cell culture lines established from patients with metastatic renal cell carcinoma (RCC). In one of these cell culture lines, UOK 123, we found no surface expression of β2-microglobulin (β2m) and MHC class I by flow cytometry. Immunofluorescence staining using three different monoclonal antibodies to β2m revealed no detectable β2m in the endoplasmic reticulum (ER), Golgi apparatus, cytoplasm, or on the cell surface. There was no evidence of folded class I molecules inside or on the surface of the cells; however, the ER stained intensively for unfolded class I molecules. Transient expression of β2m by UOK 123 after infection with a recombinant vaccinia virus containing the gene for β2m resulted in normal expression of both β2m and class I (HLA-A, B, C) determinants assessed by flow cytometry analysis. No expression of class I or β2m was seen with the recombinant vaccinia vector carrying a control gene. The inability of class I molecules to reach the cell surface is due to the requirement of β2m for proper folding and presentation of the class I MHC complex. The failure to assemble and express MHC class I complex on the cell surface renders these cells incapable of antigen presentation to cyto-toxic T cells and provides a mechanism for escape from immune recognition by the tumor. PMID:7582258

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    1992-09-01

    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

  17. Half-Heusler thermoelectrics: a complex class of materials.

    PubMed

    Bos, Jan-Willem G; Downie, Ruth A

    2014-10-29

    Half-Heusler thermoelectrics first attracted interest in the late-1990s and are currently undergoing a renaissance. This has been driven by improved synthesis, processing and characterisation methods, leading to increases in the thermoelectric figure of merit and the observation of novel phenomena such as carrier filtering in nanocomposite samples. The difficulty in extracting good thermoelectric performance is at first glance surprising given the relative simplicity of the ideal crystal structure with only site occupancies and lattice parameter as crystallographic variables. However, the observed thermoelectric properties are found to depend sensitively on sample processing. Recent work has shown that prepared ingots can contain a range of inhomogeneities, including interstitials, nano- and micron sized Heusler inclusions and multiple half-Heusler phases. For this reason, the prepared materials are far more complex than initially appreciated and this may offer opportunities to enhance the thermoelectric figure of merit.

  18. Early Endosomes Are Required for Major Histocompatiblity Complex Class II Transport to Peptide-loading Compartments

    PubMed Central

    Brachet, Valérie; Péhau-Arnaudet, Gérard; Desaymard, Catherine; Raposo, Graça; Amigorena, Sebastian

    1999-01-01

    Antigen presentation to CD4+ T lymphocytes requires transport of newly synthesized major histocompatibility complex (MHC) class II molecules to the endocytic pathway, where peptide loading occurs. This step is mediated by a signal located in the cytoplasmic tail of the MHC class II-associated Ii chain, which directs the MHC class II-Ii complexes from the trans-Golgi network (TGN) to endosomes. The subcellular machinery responsible for the specific targeting of MHC class II molecules to the endocytic pathway, as well as the first compartments these molecules enter after exit from the TGN, remain unclear. We have designed an original experimental approach to selectively analyze this step of MHC class II transport. Newly synthesized MHC class II molecules were caused to accumulate in the Golgi apparatus and TGN by incubating the cells at 19°C, and early endosomes were functionally inactivated by in vivo cross-linking of transferrin (Tf) receptor–containing endosomes using Tf-HRP complexes and the HRP-insoluble substrate diaminobenzidine. Inactivation of Tf-containing endosomes caused a marked delay in Ii chain degradation, peptide loading, and MHC class II transport to the cell surface. Thus, early endosomes appear to be required for delivery of MHC class II molecules to the endocytic pathway. Under cross-linking conditions, most αβIi complexes accumulated in tubules and vesicles devoid of γ-adaptin and/or mannose-6-phosphate receptor, suggesting an AP1-independent pathway for the delivery of newly synthesized MHC class II molecules from the TGN to endosomes. PMID:10473634

  19. Molecular characterization of major histocompatibility complex class 1 (MHC-I) from squirrel monkeys (Saimiri sciureus).

    PubMed

    Pascalis, Hervé; Heraud, Jean-Michel; Fendel, Rolf; Lavergne, Anne; Kazanji, Mirdad

    2003-12-01

    Little is known about the major histocompatibility complex (MHC) class 1 in squirrel monkeys ( Saimiri sciureus). We cloned, sequenced and characterized two alleles and the cDNA of the coding region of MHC class 1 in these New World monkeys. Phylogenetic analyses showed that these sequences are related to HLA class 1 genes ( HLA-A and HLA-G). The structure and organization of one of the two identified clones was similar to that of a class 1 MHC gene ( HLA-A2). All the exon/intron splice acceptor/donor sites are conserved and their locations correspond to the HLA-A2 gene. The sequences of the newly described cDNAs reveal that they code for the characteristic class 1 MHC proteins, with all the features thought necessary for cell surface expression. Typical sequences for the leader peptide, alpha(1), alpha(2), alpha(3), transmembrane and cytoplasmic domains were found.

  20. Dynamics of Major Histocompatibility Complex Class II Compartments during B Cell Receptor–mediated Cell Activation

    PubMed Central

    Lankar, Danielle; Vincent-Schneider, Hélène; Briken, Volker; Yokozeki, Takeaki; Raposo, Graça; Bonnerot, Christian

    2002-01-01

    Antigen recognition by clonotypic B cell receptor (BcR) is the first step of B lymphocytes differentiation into plasmocytes. This B cell function is dependent on efficient major histocompatibility complex (MHC) class II–restricted presentation of BcR-bound antigens. In this work, we analyzed the subcellular mechanisms underlying antigen presentation after BcR engagement on B cells. In quiescent B cells, we found that MHC class II molecules mostly accumulated at the cell surface and in an intracellular pool of tubulovesicular structures, whereas H2-M molecules were mostly detected in distinct lysosomal compartments devoid of MHC class II. BcR stimulation induced the transient intracellular accumulation of MHC class II molecules in newly formed multivesicular bodies (MVBs), to which H2-M was recruited. The reversible downregulation of cathepsin S activity led to the transient accumulation of invariant chain–MHC class II complexes in MVBs. A few hours after BcR engagement, cathepsin S activity increased, the p10 invariant chain disappeared, and MHC class II–peptide complexes arrived at the plasma membrane. Thus, BcR engagement induced the transient formation of antigen-processing compartments, enabling antigen-specific B cells to become effective antigen-presenting cells. PMID:11854359

  1. 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

  2. Subtle conformational changes induced in major histocompatibility complex class II molecules by binding peptides.

    PubMed

    Chervonsky, A V; Medzhitov, R M; Denzin, L K; Barlow, A K; Rudensky, A Y; Janeway, C A

    1998-08-18

    Intracellular trafficking of major histocompatibility complex (MHC) class II molecules is characterized by passage through specialized endocytic compartment(s) where antigenic peptides replace invariant chain fragments in the presence of the DM protein. These changes are accompanied by structural transitions of the MHC molecules that can be visualized by formation of compact SDS-resistant dimers, by changes in binding of mAbs, and by changes in T cell responses. We have observed that a mAb (25-9-17) that is capable of staining I-Ab on the surface of normal B cells failed to interact with I-Ab complexes with a peptide derived from the Ealpha chain of the I-E molecule but bound a similar covalent complex of I-Ab with the class II binding fragment (class II-associated invariant chain peptides) of the invariant chain. Moreover, 25-9-17 blocked activation of several I-Ab-reactive T cell hybridomas but failed to block others, suggesting that numerous I-Ab-peptide complexes acquire the 25-9-17(+) or 25-9-17(-) conformation. Alloreactive T cells were also able to discriminate peptide-dependent variants of MHC class II molecules. Thus, peptides impose subtle structural transitions upon MHC class II molecules that affect T cell recognition and may thus be critical for T cell selection and autiommunity.

  3. Differential Transmembrane Domain GXXXG Motif Pairing Impacts Major Histocompatibility Complex (MHC) Class II Structure*

    PubMed Central

    Dixon, Ann M.; Drake, Lisa; Hughes, Kelly T.; Sargent, Elizabeth; Hunt, Danielle; Harton, Jonathan A.; Drake, James R.

    2014-01-01

    Major histocompatibility complex (MHC) class II molecules exhibit conformational heterogeneity, which influences their ability to stimulate CD4 T cells and drive immune responses. Previous studies suggest a role for the transmembrane domain of the class II αβ heterodimer in determining molecular structure and function. Our previous studies identified an MHC class II conformer that is marked by the Ia.2 epitope. These Ia.2+ class II conformers are lipid raft-associated and able to drive both tyrosine kinase signaling and efficient antigen presentation to CD4 T cells. Here, we establish that the Ia.2+ I-Ak conformer is formed early in the class II biosynthetic pathway and that differential pairing of highly conserved transmembrane domain GXXXG dimerization motifs is responsible for formation of Ia.2+ versus Ia.2− I-Ak class II conformers and controlling lipid raft partitioning. These findings provide a molecular explanation for the formation of two distinct MHC class II conformers that differ in their inherent ability to signal and drive robust T cell activation, providing new insight into the role of MHC class II in regulating antigen-presenting cell-T cell interactions critical to the initiation and control of multiple aspects of the immune response. PMID:24619409

  4. Ii Chain Controls the Transport of Major Histocompatibility Complex Class II Molecules to and from Lysosomes

    PubMed Central

    Brachet, Valérie; Raposo, Graça; Amigorena, Sebastian; Mellman, Ira

    1997-01-01

    Major histocompatibility complex class II molecules are synthesized as a nonameric complex consisting of three αβ dimers associated with a trimer of invariant (Ii) chains. After exiting the TGN, a targeting signal in the Ii chain cytoplasmic domain directs the complex to endosomes where Ii chain is proteolytically processed and removed, allowing class II molecules to bind antigenic peptides before reaching the cell surface. Ii chain dissociation and peptide binding are thought to occur in one or more postendosomal sites related either to endosomes (designated CIIV) or to lysosomes (designated MIIC). We now find that in addition to initially targeting αβ dimers to endosomes, Ii chain regulates the subsequent transport of class II molecules. Under normal conditions, murine A20 B cells transport all of their newly synthesized class II I-Ab αβ dimers to the plasma membrane with little if any reaching lysosomal compartments. Inhibition of Ii processing by the cysteine/serine protease inhibitor leupeptin, however, blocked transport to the cell surface and caused a dramatic but selective accumulation of I-Ab class II molecules in lysosomes. In leupeptin, I-Ab dimers formed stable complexes with a 10-kD NH2-terminal Ii chain fragment (Ii-p10), normally a transient intermediate in Ii chain processing. Upon removal of leupeptin, Ii-p10 was degraded and released, I-Ab dimers bound antigenic peptides, and the peptide-loaded dimers were transported slowly from lysosomes to the plasma membrane. Our results suggest that alterations in the rate or efficiency of Ii chain processing can alter the postendosomal sorting of class II molecules, resulting in the increased accumulation of αβ dimers in lysosome-like MIIC. Thus, simple differences in Ii chain processing may account for the highly variable amounts of class II found in lysosomal compartments of different cell types or at different developmental stages. PMID:9105036

  5. A general model of invariant chain association with class II major histocompatibility complex proteins.

    PubMed Central

    Lee, C; McConnell, H M

    1995-01-01

    The binding of invariant chain to major histocompatibility complex (MHC) proteins is an important step in processing of MHC class II proteins and in antigen presentation. The question of how invariant chain can bind to all MHC class II proteins is central to understanding these processes. We have employed molecular modeling to predict the structure of class II-associated invariant chain peptide (CLIP)-MHC protein complexes and to ask whether the predicted mode of association could be general across all MHC class II proteins. CLIP fits identically into the MHC class II alleles HLA-DR3, I-Ak, I-Au, and I-Ad, with a consistent pattern of hydrogen bonds, contacts, and hydrophobic burial and without bad contacts. Our model predicts the burial of CLIP residues Met-91 and Met-99 in the deep P1 and P9 anchor pockets and other detailed interactions, which we have compared with available data. The predicted pattern of I-A allele-specific effects on CLIP binding is very similar to that observed experimentally by alanine-scanning mutations of CLIP. Together, these results indicate that CLIP may bind in a single, general way across products of MHC class II alleles. Images Fig. 1 Fig. 2 Fig. 3 PMID:7667280

  6. Transcriptional and posttranscriptional regulation of class I major histocompatibility complex genes following transformation with human adenoviruses.

    PubMed Central

    Shemesh, J; Rotem-Yehudar, R; Ehrlich, R

    1991-01-01

    Transformation of rodent cells by human adenoviruses is a well-established model system for studying the expression, regulation, and function of class I antigens. In this report, we demonstrate that the highly oncogenic adenovirus type 12 operates at the transcriptional and posttranscriptional levels in regulating the activity of major histocompatibility complex class I genes and products in transformed cells. Adenovirus type 12 suppresses the cell surface expression of class I antigens in most cell lines. Nevertheless, in a number of cell lines suppression is the result of reduction in the amount of stable specific mRNA, while in another group of cell lines suppression involves interference with processing of a posttranscriptional product. The two mechanisms operate both for the endogenous H-2 genes and for a miniature swine class I transgene that is expressed in the cells. Images PMID:1895404

  7. 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…

  8. 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…

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

    PubMed

    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.

  10. A structural transition in class II major histocompatibility complex proteins at mildly acidic pH

    PubMed Central

    1996-01-01

    Peptide binding by class II major histocompatibility complex proteins is generally enhanced at low pH in the range of hydrogen ion concentrations found in the endosomal compartments of antigen- presenting cells. We and others have proposed that class II molecules undergo a reversible conformational change at low pH that is associated with enhanced peptide loading. However, no one has previously provided direct evidence for a structural change in class II proteins in the mildly acidic pH conditions in which enhanced peptide binding is observed. In this study, susceptibility to denaturation induced by sodium dodecyl sulfate (SDS) detergent or heat was used to probe the conformation of class II at different hydrogen ion concentrations. Class II molecules became sensitive to denaturation at pH 5.5-6.5 depending on the allele and experimental conditions. The observed structural transition was fully reversible if acidic pH was neutralized before exposure to SDS or heat. Experiments with the environment- sensitive fluorescent probe ANS (8-anilino-1-naphthalene-sulfonic acid) provided further evidence for a reversible structural transition at mildly acidic pH associated with an increase in exposed hydrophobicity in class II molecules. IAd conformation was found to change at a higher pH than IEd, IEk, or IAk, which correlates with the different pH optimal for peptide binding by these molecules. We conclude that pH regulates peptide binding by influencing the structure of class II molecules. PMID:8551215

  11. A second lineage of mammalian major histocompatibility complex class I genes.

    PubMed Central

    Bahram, S; Bresnahan, M; Geraghty, D E; Spies, T

    1994-01-01

    Major histocompatibility complex (MHC) class I genes typically encode polymorphic peptide-binding chains which are ubiquitously expressed and mediate the recognition of intracellular antigens by cytotoxic T cells. They constitute diverse gene families in different species and include the numerous so-called nonclassical genes in the mouse H-2 complex, of which some have been adapted to variously modified functions. We have identified a distinct family of five related sequences in the human MHC which are distantly homologous to class I chains. These MIC genes (MHC class I chain-related genes) evolved in parallel with the human class I genes and with those of most if not all mammalian orders. The MICA gene in this family is located near HLA-B and is by far the most divergent mammalian MHC class I gene known. It is further distinguished by its unusual exon-intron organization and preferential expression in fibroblasts and epithelial cells. However, the presence of diagnostic residues in the MICA amino acid sequence translated from cDNA suggests that the putative MICA chain folds similarly to typical class I chains and may have the capacity to bind peptide or other short ligands. These results define a second lineage of evolutionarily conserved MHC class I genes. This implies that MICA and possibly other members in this family have been selected for specialized functions that are either ancient or derived from those of typical MHC class I genes, in analogy to some of the nonclassical mouse H-2 genes. Images PMID:8022771

  12. Lipopeptides: a novel antigen repertoire presented by major histocompatibility complex class I molecules.

    PubMed

    Morita, Daisuke; Sugita, Masahiko

    2016-10-01

    Post-translationally modified peptides, such as those containing either phosphorylated or O-glycosylated serine/threonine residues, may be presented to cytotoxic T lymphocytes (CTLs) by MHC class I molecules. Most of these modified peptides are captured in the MHC class I groove in a similar manner to that for unmodified peptides. N-Myristoylated 5-mer lipopeptides have recently been identified as a novel chemical class of MHC class I-presented antigens. The rhesus classical MHC class I allele, Mamu-B*098, was found to be capable of binding N-myristoylated lipopeptides and presenting them to CTLs. A high-resolution X-ray crystallographic analysis of the Mamu-B*098:lipopeptide complex revealed that the myristic group as well as conserved C-terminal serine residue of the lipopeptide ligand functioned as anchors, whereas the short stretch of three amino acid residues located in the middle of the lipopeptides was only exposed externally with the potential to interact directly with specific T-cell receptors. Therefore, the modes of lipopeptide-ligand interactions with MHC class I and with T-cell receptors are novel and fundamentally distinct from that for MHC class I-presented peptides. Another lipopeptide-presenting MHC class I allele has now been identified, leading us to the prediction that MHC class I molecules may be separated on a functional basis into two groups: one presenting long peptides and the other presenting short lipopeptides. Since the N-myristoylation of viral proteins is often linked to pathogenesis, CTLs capable of sensing N-myristoylation may serve to control pathogenic viruses, raising the possibility for the development of a new type of lipopeptide vaccine. © 2016 John Wiley & Sons Ltd.

  13. Error threshold in optimal coding, numerical criteria, and classes of universalities for complexity

    NASA Astrophysics Data System (ADS)

    Saakian, David B.

    2005-01-01

    The free energy of the random energy model at the transition point between the ferromagnetic and spin glass phases is calculated. At this point, equivalent to the decoding error threshold in optimal codes, the free energy has finite size corrections proportional to the square root of the number of degrees. The response of the magnetization to an external ferromagnetic phase is maximal at values of magnetization equal to one-half. We give several criteria of complexity and define different universality classes. According to our classification, at the lowest class of complexity are random graphs, Markov models, and hidden Markov models. At the next level is the Sherrington-Kirkpatrick spin glass, connected to neuron-network models. On a higher level are critical theories, the spin glass phase of the random energy model, percolation, and self-organized criticality. The top level class involves highly optimized tolerance design, error thresholds in optimal coding, language, and, maybe, financial markets. Living systems are also related to the last class. The concept of antiresonance is suggested for complex systems.

  14. Major histocompatibility complex class II antigen expression in B and T cell non-Hodgkin's lymphoma.

    PubMed Central

    Smith, M E; Holgate, C S; Williamson, J M; Grigor, I; Quirke, P; Bird, C C

    1987-01-01

    An immunohistochemical study of 46 B and T cell non-Hodgkin's lymphomas, using monoclonal antibodies to the products of the major histocompatibility complex (MHC) class II antigen subregions, DP, DQ, and DR, showed that most B and T cell lymphomas express these antigens. Both coordinate and non-coordinate expression of MHC class II antigens was observed, but this did not correlate with immunological phenotype, morphological grade, or proliferation index as determined by flow cytometry. Images Fig 1 Fig 2 Fig 3 PMID:3546388

  15. Race, Ethnicity and Social Class and the Complex Etiologies of Asthma

    PubMed Central

    Drake, Katherine A; Galanter, Joshua M; Burchard, Esteban Gonzalez

    2009-01-01

    Summary Asthma is a common but complex respiratory disease caused by the interaction of genetic and environmental factors. Significant racial and ethnic disparities in prevalence, mortality, and drug response have been described. These disparities may be explained by racial and ethnic-specific variation in genetic, environmental, social and psychological risk factors. In addition, race, ethnicity, and social class are important proxies for unmeasured factors that influence health outcomes. Herein, we review salient differences in the etiologies of asthma by race, ethnicity and social class, and argue for their continued use as variables in asthma research. PMID:18384258

  16. Molecular characterization of major histocompatibility complex class II alleles in wild tiger salamanders (Ambystoma tigrinum).

    PubMed

    Bos, David H; DeWoody, J Andrew

    2005-11-01

    Major histocompatibility complex (MHC) class II genes are usually among the most polymorphic in vertebrate genomes because of their critical role (antigen presentation) in immune response. Prior to this study, the MHC was poorly characterized in tiger salamanders (Ambystoma tigrinum), but the congeneric axolotl (Ambystoma mexicanum) is thought to have an unusual MHC. Most notably, axolotl class II genes lack allelic variation and possess a splice variant without a full peptide binding region (PBR). The axolotl is considered immunodeficient, but it is unclear how or to what extent MHC genetics and immunodeficiency are interrelated. To study the evolution of MHC genes in urodele amphibians, we describe for the first time an expressed polymorphic class II gene in wild tiger salamanders. We sequenced the PBR of a class II gene from wild A. tigrinum (n=33) and identified nine distinct alleles. Observed heterozygosity was 73%, and there were a total of 46 polymorphic sites, most of which correspond to amino acid positions that bind peptides. Patterns of nucleotide substitutions exhibit the signature of diversifying selection, but no recombination was detected. Not surprisingly, trans-species evolution of tiger salamander and axolotl class II alleles was apparent. We have no direct data on the immunodeficiency of tiger salamanders, but the levels of polymorphism in our study population should suffice to bind a variety of foreign peptides (unlike axolotls). Our tiger salamander data suggest that the monomorphism and immunodeficiencies associated with axolotl class II genes is a relic of their unique historical demography, not their phylogenetic legacy.

  17. 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.

  18. 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.

  19. Expression of major histocompatibility complex class II and costimulatory molecules in oral carcinomas in vitro.

    PubMed

    Villarroel-Dorrego, Mariana; Speight, Paul M; Barrett, A William

    2005-01-01

    Recognition in the 1980 s that keratinocytes can express class II molecules of the Major Histocompatibility Complex (MHC) first raised the possibility that these cells might have an immunological function, and may even act as antigen presenting cells (APC). For effective T lymphocyte activation, APC require, in addition to MHC II, appropriate costimulatory signals. The aim of this study was to determine the expression of MHC class II and the co-stimulatory molecules CD40, CD80 and CD86 in keratinocytes derived from healthy oral mucosa and oral carcinomas. Using flow cytometry, it was confirmed that oral keratinocytes, switch on, expression of MHC class II molecules after stimulation with IFNgamma in vitro. All keratinocyte lines expressed CD40 constitutively; by contrast, CD80 and CD86 were universally absent. Loss of CD80 and CD86 may be one means whereby tumours escape immunological surveillance.

  20. Class II major histocompatibility complex tetramer staining: progress, problems, and prospects

    PubMed Central

    Vollers, Sabrina S; Stern, Lawrence J

    2008-01-01

    The use of major histocompatibility complex (MHC) tetramers in the detection and analysis of antigen-specific T cells has become more widespread since its introduction 11 years ago. Early challenges in the application of tetramer staining to CD4+ T cells centred around difficulties in the expression of various class II MHC allelic variants and the detection of low-frequency T cells in mixed populations. As many of the technical obstacles to class II MHC tetramer staining have been overcome, the focus has returned to uncertainties concerning how oligomer valency and T-cell receptor/MHC affinity affect tetramer binding. Such issues have become more important with an increase in the number of studies relying on direct ex vivo analysis of antigen-specific CD4+ T cells. In this review we discuss which problems in class II MHC tetramer staining have been solved to date, and which matters remain to be considered. PMID:18251991

  1. Distributed robust adaptive control for a class of dynamical complex networks against imperfect communications

    NASA Astrophysics Data System (ADS)

    Jin, Xiao-Zheng; Yang, Guang-Hong

    2011-03-01

    In this article, a robust tracking control problem of a class of dynamical complex networks is presented through a distributed adaptive approach. Uncertain network topology with unknown coupling strength, delayed and perturbed communications and external disturbances are considered, while the bounds of channel noises and coupling delays and disturbances are assumed to be unknown. Adaptation laws are proposed to estimate the network coupling strength and the upper and lower bounds of communication state errors and disturbances on-line. Based on the information from adaptive schemes, a class of distributed robust adaptive controllers is constructed to automatically compensate for the imperfect network and disturbance effects. Then, according to the Lyapunov stability theory, it is shown that the achievement of tracking for complex networks is effective on imperfect communications and disturbances. The effectiveness of the proposed design is illustrated via a decoupled longitudinal model of an F-18 aircraft.

  2. Prediction of peptide binding to a major histocompatibility complex class I molecule based on docking simulation.

    PubMed

    Ishikawa, Takeshi

    2016-10-01

    Binding between major histocompatibility complex (MHC) class I molecules and immunogenic epitopes is one of the most important processes for cell-mediated immunity. Consequently, computational prediction of amino acid sequences of MHC class I binding peptides from a given sequence may lead to important biomedical advances. In this study, an efficient structure-based method for predicting peptide binding to MHC class I molecules was developed, in which the binding free energy of the peptide was evaluated by two individual docking simulations. An original penalty function and restriction of degrees of freedom were determined by analysis of 361 published X-ray structures of the complex and were then introduced into the docking simulations. To validate the method, calculations using a 50-amino acid sequence as a prediction target were performed. In 27 calculations, the binding free energy of the known peptide was within the top 5 of 166 peptides generated from the 50-amino acid sequence. Finally, demonstrative calculations using a whole sequence of a protein as a prediction target were performed. These data clearly demonstrate high potential of this method for predicting peptide binding to MHC class I molecules.

  3. An atlas of the thioredoxin fold class reveals the complexity of function-enabling adaptations.

    PubMed

    Atkinson, Holly J; Babbitt, Patricia C

    2009-10-01

    The group of proteins that contain a thioredoxin (Trx) fold is huge and diverse. Assessment of the variation in catalytic machinery of Trx fold proteins is essential in providing a foundation for understanding their functional diversity and predicting the function of the many uncharacterized members of the class. The proteins of the Trx fold class retain common features-including variations on a dithiol CxxC active site motif-that lead to delivery of function. We use protein similarity networks to guide an analysis of how structural and sequence motifs track with catalytic function and taxonomic categories for 4,082 representative sequences spanning the known superfamilies of the Trx fold. Domain structure in the fold class is varied and modular, with 2.8% of sequences containing more than one Trx fold domain. Most member proteins are bacterial. The fold class exhibits many modifications to the CxxC active site motif-only 56.8% of proteins have both cysteines, and no functional groupings have absolute conservation of the expected catalytic motif. Only a small fraction of Trx fold sequences have been functionally characterized. This work provides a global view of the complex distribution of domains and catalytic machinery throughout the fold class, showing that each superfamily contains remnants of the CxxC active site. The unifying context provided by this work can guide the comparison of members of different Trx fold superfamilies to gain insight about their structure-function relationships, illustrated here with the thioredoxins and peroxiredoxins.

  4. Peptide influences the folding and intracellular transport of free major histocompatibility complex class I heavy chains

    PubMed Central

    1995-01-01

    Class I major histocompatibility complex molecules require both beta 2- microglobulin (beta 2m) and peptide for efficient intracellular transport. With the exception of H-2Db and Ld, class I heavy chains have not been detectable at the surface of cells lacking beta 2m. We show that properly conformed class I heavy chains can be detected in a terminally glycosylated form indicative of cell surface expression in H- 2b, H-2d, and H-2s beta 2m-/- concanavalin A (Con A)-stimulated splenocytes incubated at reduced temperature. Furthermore, we demonstrate the presence of Kb molecules at the surface of beta 2m-/- cells cultured at 37 degrees C. The mode of assembly of class I molecules encompasses two major pathways: binding of peptide to preformed "empty" heterodimers, and binding of peptide to free heavy chains, followed by recruitment of beta 2m. In support of the existence of the latter pathway, we provide evidence for a role of peptide in intracellular transport of free class I heavy chains, through analysis of Con A-stimulated splenocytes from transporter associated with antigen processing 1 (TAP1)-/-, beta 2m-/-, and double-mutant TAP1/beta 2m-/- mice. PMID:7869032

  5. Reassociation with beta 2-microglobulin is necessary for Kb class I major histocompatibility complex binding of exogenous peptides.

    PubMed Central

    Rock, K L; Rothstein, L E; Gamble, S R; Benacerraf, B

    1990-01-01

    T lymphocytes recognize endogenously produced antigenic peptides in association with major histocompatibility complex (MHC)-encoded molecules. Peptides from the extracellular fluid can be displayed in association with class I and class II MHC molecules. Here we report that mature Kb class I MHC molecules bind peptides upon dissociation and reassociation of their light chain. Intact Kb heterodimers, unlike class II MHC molecules, are relatively unreceptive to binding peptides. This property may maintain segregation of class I and class II MHC-restricted peptides and has implications for the use of peptides as vaccines. Images PMID:2217182

  6. 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.

  7. N-containing Ag(I) and Hg(II) complexes: a new class of antibiotics.

    PubMed

    Sabounchei, Seyyed Javad; Shahriary, Parisa

    2013-01-01

    Several classes of antimicrobial compounds are presently available; microorganism's resistance to these drugs constantly emerges. In order to prevent this serious medical problem, the elaboration of new types of antibacterial agents or the expansion of bioactivity of the naturally known biosensitive compounds is a very interesting research problem. The synthesis and characterization of metal complexes with organic bioactive ligands is one of the promising fields for the search. The biological activities of the metal complexes differ from those of either the ligand or the metal ion. The results obtained thus far have led to the conclusion that structural factors, which govern antimicrobial activities, are strongly dependent on the central metal ion. A review of papers dealing with the Ag(I) and Hg(II) complexes of N donor ligands is presented. These metal complexes of N-chelating ligands have attracted considerable attention because of their interesting physicochemical properties and pronounced biological activities. This review will mainly focus on the preparation procedures and antibacterial properties of free organic ligands and the corresponding complexes. Finally, a research about antimicrobial properties of new Hg(II) complexes with 5-methyl-5-(4-pyridyl)-2,4-imidazolidenedione (L) and various halogen ions, HgL2X2 (X = Cl¯ (49), Br¯ (50), and I¯ (51)), is reported. Noteworthy antimicrobial activities, evaluated by minimum inhibitory concentration, for these complexes were observed.

  8. Crystal structure of staphylococcal enterotoxin I (SEI) in complex with a human major histocompatibility complex class II molecule.

    PubMed

    Fernández, Marisa M; Guan, Rongjin; Swaminathan, Chittoor P; Malchiodi, Emilio L; Mariuzza, Roy A

    2006-09-01

    Superantigens are bacterial or viral proteins that elicit massive T cell activation through simultaneous binding to major histocompatibility complex (MHC) class II and T cell receptors. This activation results in uncontrolled release of inflammatory cytokines, causing toxic shock. A remarkable property of superantigens, which distinguishes them from T cell receptors, is their ability to interact with multiple MHC class II alleles independently of MHC-bound peptide. Previous crystallographic studies have shown that staphylococcal and streptococcal superantigens belonging to the zinc family bind to a high affinity site on the class II beta-chain. However, the basis for promiscuous MHC recognition by zinc-dependent superantigens is not obvious, because the beta-chain is polymorphic and the MHC-bound peptide forms part of the binding interface. To understand how zinc-dependent superantigens recognize MHC, we determined the crystal structure, at 2.0 A resolution, of staphylococcal enterotoxin I bound to the human class II molecule HLA-DR1 bearing a peptide from influenza hemagglutinin. Interactions between the superantigen and DR1 beta-chain are mediated by a zinc ion, and 22% of the buried surface of peptide.MHC is contributed by the peptide. Comparison of the staphylococcal enterotoxin I.peptide.DR1 structure with ones determined previously revealed that zinc-dependent superantigens achieve promiscuous binding to MHC by targeting conservatively substituted residues of the polymorphic beta-chain. Additionally, these superantigens circumvent peptide specificity by engaging MHC-bound peptides at their conformationally conserved N-terminal regions while minimizing sequence-specific interactions with peptide residues to enhance cross-reactivity.

  9. 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

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

    PubMed

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

    2016-09-07

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Chicken major histocompatibility complex class II molecules of the B haplotype present self and foreign peptides.

    PubMed

    Cumberbatch, J A; Brewer, D; Vidavsky, I; Sharif, S

    2006-08-01

    The chicken major histocompatibility complex (MHC), or B-complex, mediates genetic resistance and susceptibility to infectious disease. For example, the B19 haplotype is associated with susceptibility to Marek's disease. Here, we describe the sequencing and analysis of peptides presented by B19 MHC class II molecules. A B19/B19 B-cell line was used for the immunoaffinity purification of MHC class II molecules, which was followed by acid elution of the bound peptides. The eluted peptides were then analysed using tandem mass spectrometry. Thirty peptide sequences were obtained, ranging from 11 to 25 amino acids in length. Source protein cellular localization included the plasma membrane, cytosol and endosomal pathway. In addition, five peptides from the envelope glycoprotein of chicken syncytial virus (CSV) were identified. Chicken syncytial virus had been used as a helper virus along with reticuloendotheliosis virus strain T for transformation of B19/B19B cells. Alignment and analysis of the peptide sequence pool provided a putative peptide-binding motif for the B19 MHC class II.

  12. Class I major histocompatibility complex antigens and tumor ploidy in breast and bronchogenic carcinomas.

    PubMed

    Redondo, M; Concha, A; Ruiz-Cabello, F; Morell, M; Esteban, F; Talavera, P; Garrido, F

    1997-01-01

    We determined the frequency of expression of the major histocompatibility complex antigens HLA-A,B,C in tumor cells from 207 primary tumor lesions of breast and bronchogenic carcinomas, to see if the expression of theses antigens was linked with several clinicopathological parameters associated with tumor aggressivity, such as abnormal cellular DNA content. We compared tumor tissues with nonneoplastic tissues and tissues from 15 benign breast lesions. HLA class I expressor and nonexpressor tumor cells were determined by using immunohistochemical stains (PAP and APAAP methods) and antibodies against these antigens. Reduction of HLA class I antigen was detected in 65 tumors (31.7%) and was significantly associated with poor tumor differentiation and abnormal cellular DNA content (p < 0.001). These characteristics might define a group of aggressive tumors in which the decrease of HLA class I antigens would enable tumor cells to avoid eliciting host immune responses. On the other hand, the altered regulatory mechanisms, of tumors with abnormal cellular DNA content, might modulate the expression of HLA class I molecules.

  13. Evolutionary relationships of major histocompatibility complex class I genes in simian primates.

    PubMed

    Sawai, Hiromi; Kawamoto, Yoshi; Takahata, Naoyuki; Satta, Yoko

    2004-04-01

    New World monkeys (NWMs) occupy a critical phylogenetic position in elucidating the evolutionary process of major histocompatibility complex (MHC) class I genes in primates. From three subfamilies of Aotinae, Cebinae, and Atelinae, the 5'-flanking regions of 18 class I genes are obtained and phylogenetically examined in terms of Alu/LINE insertion elements as well as the nucleotide substitutions. Two pairs of genes from Aotinae and Atelinae are clearly orthologous to human leukocyte antigen (HLA) -E and -F genes. Of the remaining 14 genes, 8 belong to the distinct group B, together with HLA-B and -C, to the exclusion of all other HLA class I genes. These NWM genes are classified into four groups, designated as NWM-B1, -B2, -B3, and -B4. Of these, NWM-B2 is orthologous to HLA-B/C. Also, orthologous relationships of NWM-B1, -B2, and -B3 exist among different families of Cebidae and Atelidae, which is in sharp contrast to the genus-specific gene organization within the subfamily Callitrichinae. The other six genes belong to the distinct group G. However, a clade of these NWM genes is almost equally related to HLA-A, -J, -G, and -K, and there is no evidence for their orthologous relationships to HLA-G. It is argued that class I genes in simian primates duplicated extensively in their common ancestral lineage and that subsequent evolution in descendant species has been facilitated mainly by independent loss of genes.

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

    PubMed

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

    2015-11-23

    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.

  15. 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.

  16. 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

  17. 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.

  18. A new class of macrocyclic lanthanide complexes for cell labeling and magnetic resonance imaging applications.

    PubMed

    Zheng, Quan; Dai, Houquan; Merritt, Matthew E; Malloy, Craig; Pan, Cai Yuan; Li, Wen-Hong

    2005-11-23

    Lanthanide complexes have wide applications in biochemical research and biomedical imaging. We have designed and synthesized a new class of macrocyclic lanthanide chelates, Ln/DTPA-PDA-C(n), for cell labeling and magnetic resonance imaging (MRI) applications. Two lipophilic Gd3+ complexes, Gd/DTPA-PDA-C(n) (n = 10, 12), labeled a number of cultured mammalian cells noninvasively at concentrations as low as a few micromolar. Cells took up these agents rapidly and showed robust intensity increases in T1-weighed MR images. Labeled cells showed normal morphology and doubling time as control cells. In addition to cultured cells, these agents also labeled primary cells in tissues such as dissected pancreatic islets. To study the mechanism of cellular uptake, we applied the technique of diffusion enhanced fluorescence resonance energy transfer (DEFRET) to determine the cellular localization of these lipophilic lanthanide complexes. After loading cells with a luminescent complex, Tb/DTPA-PDA-C10, we observed DEFRET between the Tb3+ complex and extracellular, but not intracellular, calcein. We concluded that these cyclic lanthanide complexes label cells by inserting two hydrophobic alkyl chains into cell membranes with the hydrophilic metal binding site facing the extracellular medium. As the first imaging application of these macrocyclic lanthanide chelates, we labeled insulin secreting beta-cells with Gd/DTPA-PDA-C12. Labeled cells were encapsulated in hollow fibers and were implanted in a nude mouse. MR imaging of implanted beta-cells showed that these cells could be followed in vivo for up to two weeks. The combined advantages of this new class of macrocyclic contrast agents ensure future imaging applications to track cell movement and localization in different biological systems.

  19. Characterisation of four major histocompatibility complex class II genes of the koala (Phascolarctos cinereus).

    PubMed

    Lau, Quintin; Jobbins, Sarah E; Belov, Katherine; Higgins, Damien P

    2013-01-01

    Major histocompatibility complex (MHC) class II molecules have an integral role in the adaptive immune response, as they bind and present antigenic peptides to T helper lymphocytes. In this study of koalas, species-specific primers were designed to amplify exon 2 of the MHC class II DA and DB genes, which contain much of the peptide-binding regions of the α and β chains. A total of two DA α1 domain variants and eight DA β1 (DAB), three DB α1 and five DB β1 variants were amplified from 20 koalas from two free-living populations from South East Queensland and the Port Macquarie region in northern New South Wales. We detected greater variation in the β1 than in the α1 domains as well as evidence of positive selection in DAB. The present study provides a springboard to future investigation of the role of MHC in disease susceptibility in koalas.

  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.

  1. Toxic shock syndrome toxin 1 binds to major histocompatibility complex class II molecules.

    PubMed Central

    Scholl, P; Diez, A; Mourad, W; Parsonnet, J; Geha, R S; Chatila, T

    1989-01-01

    Toxic shock syndrome toxin 1 (TSST-1) is a 22-kDa exotoxin produced by strains of Staphylococcus aureus and implicated in the pathogenesis of toxic shock syndrome. In common with other staphylococcal exotoxins, TSST-1 has diverse immunological effects. These include the induction of interleukin 2 receptor expression, interleukin 2 synthesis, proliferation of human T lymphocytes, and stimulation of interleukin 1 synthesis by human monocytes. In the present study, we demonstrate that TSST-1 binds with saturation kinetics and with a dissociation constant of 17-43 nM to a single class of binding sites on human mononuclear cells. There was a strong correlation between the number of TSST-1 binding sites and the expression of major histocompatibility complex class II molecules, and interferon-gamma induced the expression of class II molecules as well as TSST-1 binding sites on human skin-derived fibroblasts. Monoclonal antibodies to HLA-DR, but not to HLA-DP or HLA-DQ, strongly inhibited TSST-1 binding. Affinity chromatography of 125I-labeled cell membranes over TSST-1-agarose resulted in the recovery of two bands of 35 kDa and 31 kDa that comigrated, respectively, with the alpha and beta chains of HLA-DR and that could be immunoprecipitated with anti-HLA-DR monoclonal antibodies. Binding of TSST-1 was demonstrated to HLA-DR and HLA-DQ L-cell transfectants. These results indicate that major histocompatibility complex class II molecules represent the major binding site for TSST-1 on human cells. Images PMID:2542966

  2. STRUCTURES OF THE CLASS D CARBAPENEMASE OXA-24 FROM ACINETOBACTER BAUMANNII IN COMPLEX WITH DORIPENEM

    PubMed Central

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

    2011-01-01

    The emergence of class D β-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 baumanii. Unfortunately, class D β-lactamases with carbapenemase activity are resistant to β-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 6α 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 may be useful for the design of novel inhibitors. PMID:21215758

  3. 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.

  4. An Atlas of the Thioredoxin Fold Class Reveals the Complexity of Function-Enabling Adaptations

    PubMed Central

    Atkinson, Holly J.; Babbitt, Patricia C.

    2009-01-01

    The group of proteins that contain a thioredoxin (Trx) fold is huge and diverse. Assessment of the variation in catalytic machinery of Trx fold proteins is essential in providing a foundation for understanding their functional diversity and predicting the function of the many uncharacterized members of the class. The proteins of the Trx fold class retain common features—including variations on a dithiol CxxC active site motif—that lead to delivery of function. We use protein similarity networks to guide an analysis of how structural and sequence motifs track with catalytic function and taxonomic categories for 4,082 representative sequences spanning the known superfamilies of the Trx fold. Domain structure in the fold class is varied and modular, with 2.8% of sequences containing more than one Trx fold domain. Most member proteins are bacterial. The fold class exhibits many modifications to the CxxC active site motif—only 56.8% of proteins have both cysteines, and no functional groupings have absolute conservation of the expected catalytic motif. Only a small fraction of Trx fold sequences have been functionally characterized. This work provides a global view of the complex distribution of domains and catalytic machinery throughout the fold class, showing that each superfamily contains remnants of the CxxC active site. The unifying context provided by this work can guide the comparison of members of different Trx fold superfamilies to gain insight about their structure-function relationships, illustrated here with the thioredoxins and peroxiredoxins. PMID:19851441

  5. Major histocompatibility complex class II expression distinguishes two distinct B cell developmental pathways during ontogeny

    PubMed Central

    1994-01-01

    All mature B cells coexpress major histocompatibility complex (MHC) class II molecules, I-A and I-E, which are restriction elements required for antigen presentation to CD4+ T cells. However, the expression of class II during the early stages of B cell development has been unclear. We demonstrate here that there is a difference in the expression of class II during murine B cell development in the fetal liver and adult bone marrow (BM). These differences define two distinct B cell developmental pathways. The Fetal-type (FT) pathway is characterized by pre-B and immature IgM+ B cells generated in the fetal liver which initially lack all class II expression. In contrast, the Adult-type (AT) pathway is typified by B cells developing in the adult BM which express class II molecules from the pre-B cell stage. In vitro stromal cell cultures of sorted fetal liver and adult BM pro-B cells indicated that the difference in I-A expression during B cell development is intrinsic to the progenitors. In addition, we show that FT B cell development is not restricted to the fetal liver but occurs in the peritoneal cavities, spleens, liver, and BM of young mice up to at least 1 mo of age. The AT B cell development begins to emerge after birth but is, however, restricted to the BM environment. These findings indicate that there are two distinct B cell developmental pathways during ontogeny, each of which could contribute differentially to the immune repertoire and thus the functions of B cell subsets and lineages. PMID:7913950

  6. The analysis of eight transcriptomes from all poriferan classes reveals surprising genetic complexity in sponges.

    PubMed

    Riesgo, Ana; Farrar, Nathan; Windsor, Pamela J; Giribet, Gonzalo; Leys, Sally P

    2014-05-01

    Sponges (Porifera) are among the earliest evolving metazoans. Their filter-feeding body plan based on choanocyte chambers organized into a complex aquiferous system is so unique among metazoans that it either reflects an early divergence from other animals prior to the evolution of features such as muscles and nerves, or that sponges lost these characters. Analyses of the Amphimedon and Oscarella genomes support this view of uniqueness-many key metazoan genes are absent in these sponges-but whether this is generally true of other sponges remains unknown. We studied the transcriptomes of eight sponge species in four classes (Hexactinellida, Demospongiae, Homoscleromorpha, and Calcarea) specifically seeking genes and pathways considered to be involved in animal complexity. For reference, we also sought these genes in transcriptomes and genomes of three unicellular opisthokonts, two sponges (A. queenslandica and O. carmela), and two bilaterian taxa. Our analyses showed that all sponge classes share an unexpectedly large complement of genes with other metazoans. Interestingly, hexactinellid, calcareous, and homoscleromorph sponges share more genes with bilaterians than with nonbilaterian metazoans. We were surprised to find representatives of most molecules involved in cell-cell communication, signaling, complex epithelia, immune recognition, and germ-lineage/sex, with only a few, but potentially key, absences. A noteworthy finding was that some important genes were absent from all demosponges (transcriptomes and the Amphimedon genome), which might reflect divergence from main-stem lineages including hexactinellids, calcareous sponges, and homoscleromorphs. Our results suggest that genetic complexity arose early in evolution as shown by the presence of these genes in most of the animal lineages, which suggests sponges either possess cryptic physiological and morphological complexity and/or have lost ancestral cell types or physiological processes.

  7. Characterization of major histocompatibility complex class I and class II genes from the Tasmanian devil (Sarcophilus harrisii).

    PubMed

    Siddle, Hannah V; Sanderson, Claire; Belov, Katherine

    2007-09-01

    The Tasmanian devil (Sarcophilus harrisii) is currently threatened by an emerging wildlife disease, devil facial tumour disease. The disease is decreasing devil numbers dramatically and may lead to the extinction of the species. At present, nothing is known about the immune genes or basic immunology of the devil. In this study, we report the construction of the first genetic library for the Tasmanian devil, a spleen cDNA library, and the isolation of full-length MHC Class I and Class II genes. We describe six unique Class II beta chain sequences from at least three loci, which belong to the marsupial Class II DA gene family. We have isolated 13 unique devil Class I sequences, representing at least seven Class I loci, two of which are most likely non-classical genes. The MHC Class I sequences from the devil have little heterogeneity, indicating recent divergence. The MHC genes described here are most likely involved in antigen presentation and are an important first step for studying MHC diversity and immune response in the devil.

  8. Activation of class I major histocompatibility complex gene expression by hepatitis B virus.

    PubMed Central

    Zhou, D X; Taraboulos, A; Ou, J H; Yen, T S

    1990-01-01

    Normal hepatocytes express very few class I major histocompatibility complex (MHC I) molecules, but MHC I expression is elevated in hepatitis B virus (HBV) infection. We report here that hepatoblastoma cells with replicating HBV genomes express three- to fourfold-higher levels of MHC I protein and mRNA than do parent cells without HBV DNA. Transient transfection assays demonstrated that the HBV X protein trans activated transcription from an MHC I promoter and allowed identification of cis elements important for trans activation. Images PMID:2164611

  9. Correction of skeletal Class III malocclusion with clockwise rotation of the maxillomandibular complex.

    PubMed

    Tsai, I-Ming; Lin, Chen-Hui; Wang, Yu-Ching

    2012-02-01

    A 19-year-old woman with skeletal Class III malocclusion, paranasal depression, and a low mandibular plane angle was treated with orthodontics and orthognathic surgery. Dental decompensation and protraction of maxillary right third molar to replace maxillary right second molar were performed before surgery. Clockwise rotation of maxillo-mandibular complex was applied by Le Fort I osteotomy and bilateral sagittal split osteotomies to achieve facial balance. The active treatment period was 12 months. The stable occlusion and skeletal relationship were observed after a 10-month follow-up period. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  10. The overlooked "nonclassical" functions of major histocompatibility complex (MHC) class II antigens in immune and nonimmune cells.

    PubMed

    Altomonte, M; Pucillo, C; Maio, M

    1999-06-01

    Besides their "classical" antigenic peptide-presenting activity, major histocompatibility complex (MHC) class II antigens can activate different cellular functions in immune and nonimmune cells. However, this "nonclassical" role and its functional consequences are still substantially overlooked. In this review, we will focus on these alternative functional properties of MHC class II antigens, to reawaken attention to their present and foreseeable immunobiologic and pathogenetic implications. The main issues that will be addressed concern 1) the role of MHC class II molecules as basic components of exchangeable oligomeric protein complexes with intracellular signaling ability; 2) the nonclassical functions of MHC class II antigens in immune cells; 3) the pathogenetic role of MHC class II antigens in inflammatory/autoimmune and infectious disease; and 4) the functional role of MHC class II antigens in solid malignancies.

  11. 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.

  12. 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

  13. Structural properties and complexity of a new network class: Collatz step graphs.

    PubMed

    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.

  14. Ethanol Metabolism Alters Major Histocompatibility Complex Class I-Restricted Antigen Presentation In Liver Cells

    PubMed Central

    Osna, Natalia A.; White, Ronda L.; Thiele, Geoffrey M.; Donohue, Terrence M.

    2009-01-01

    The proteasome is a major enzyme that cleaves proteins for antigen presentation. Cleaved peptides traffic to the cell surface, where they are presented in the context of MHC class I. Recognition of these complexes by cytotoxic T lymphocytes is crucial for elimination of cells bearing “non-self” proteins. Our previous studies revealed that ethanol suppresses proteasome function in ethanol-metabolizing liver cells. We hypothesized that proteasome suppression reduces the hydrolysis of antigenic peptides, thereby decreasing the presentation of the peptide-MHC class I-complexes on the cell surface. To test this, we used the mouse hepatocyte cell line (CYP2E1/ADH-transfected HepB5 cells) or primary mouse hepatocytes, both derived from livers of C57Bl/6 mice, which present the ovalbumin peptide, SIINFEKL, complexed with H2Kb. To induce H2Kb expression, HepB5 cells were treated with interferon gamma (IFNγ) and then exposed to ethanol. In these cells, ethanol metabolism decreased not only proteasome activity, but also hydrolysis of the C-extended peptide, SIINFEKL-TE and the presentation of SIINFEKL-H2Kb complexes measured after the delivery of SIINFEKL-TE to cytoplasm. The suppressive effects of ethanol were, in part, attributed to ethanol-elicited impairment of IFNγ signaling. However, in primary hepatocytes, even in the absence of IFNγ, we observed a similar decline in proteasome activity and antigen presentation after ethanol exposure. We conclude that proteasome function is directly suppressed by ethanol metabolism and indirectly, by preventing the activating effects of IFNγ. Ethanol-elicited reduction in proteasome activity contributes to the suppression of SIINFEKL-H2Kb presentation on the surface of liver cells. Immune response to viral antigens plays a crucial role in the pathogenesis of hepatitis C or B viral infections (HCV and HBV, respectively). Professional antigen-presenting cells (dendritic cells and macrophages) are responsible for priming the

  15. 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

  16. New genes in the class II region of the human major histocompatibility complex.

    PubMed

    Hanson, I M; Poustka, A; Trowsdale, J

    1991-06-01

    A detailed map of the class II region of the human major histocompatibility complex has been constructed by pulsed-field gel electrophoresis. This map revealed clusters of sites for enzymes that cut preferentially in unmethylated CpG-rich DNA often found at the 5' ends of genes. Three of these clusters have been cloned by cosmid walking and chromosome jumping. Analysis of the clones encompassing these regions through the use of zoo blots, Northern blots, and cDNA libraries resulted in the discovery of four novel genes. The D6S111E and D6S112E genes are centromeric to the HLA-DPB2 gene, while D6S113E and D6S114E are between HLA-DNA and HLA-DOB. Preliminary characterization of the new genes indicates that they are unrelated to the class II genes themselves, although D6S114E expression, like class II expression, is inducible with interferon. In addition, the HLA-DNA gene has been accurately positioned and oriented for the first time.

  17. Recognition of class I major histocompatibility complex molecules by Ly- 49: specificities and domain interactions

    PubMed Central

    1996-01-01

    Ly-49 is a family type II transmembrane proteins encoded by a gene cluster on murine chromosome 6. One member of this family, Ly-49A, is expressed by a natural killer (NK) cell subset, binds to class I major histocompatibility complex (MHC) molecules, and blocks the killing of target cells bearing the appropriate H-2 antigens. Here we show that another member of this family which is expressed by an NK cell subset, Ly-49C, recognizes H-2b and H-2d structures which are distinct from and overlapping with those recognized by Ly-49A. Interactions between Ly- 49A and C and their class I ligands are entirely blocked by the antibodies 5E6, YE1/48, YE1/32, and A1, all of which were found to recognize epitopes contained within the carbohydrate recognition domain (CRD). However, cell-cell binding assays revealed that class I binding specificity is conferred by a combination of sequences within both the CRD and a 19-amino acid adjacent region. We also investigated the question of whether Ly-49A and C form dimers on cells which express both receptors. When coexpressed on COS cells, sequential immunoprecipitation demonstrated that these receptors pair exclusively as homodimers, with no evidence for heterodimeric structures. These observations provide insight into both the biochemical nature of the Ly- 49 family as well as the receptor functions of Ly-49C on NK cells. PMID:8666913

  18. Cloning of the major histocompatibility complex class II promoter binding protein affected in a hereditary defect in class II gene regulation.

    PubMed Central

    Reith, W; Barras, E; Satola, S; Kobr, M; Reinhart, D; Sanchez, C H; Mach, B

    1989-01-01

    The regulation of major histocompatibility complex class II gene expression is directly involved in the control of normal and abnormal immune responses. In humans, HLA-DR, -DQ, and -DP class II heterodimers are encoded by a family of alpha- and beta-chain genes clustered in the major histocompatibility complex. Their expression is developmentally controlled and normally restricted to certain cell types. This control is mediated by cis-acting sequences in class II promoters and by trans-acting regulatory factors. Several nuclear proteins bind to class II promoter sequences. In a form of hereditary immunodeficiency characterized by a defect in a trans-acting regulatory factor controlling class II gene transcription, we have observed that one of these nuclear factors (RF-X) does not bind to its target sequence (the class II X box). A cDNA encoding RF-X was isolated by screening a phage expression library with an X-box binding-site probe. The recombinant protein has the binding specificity of RF-X, including a characteristic gradient of affinity for the X boxes of HLA-DR, -DP, and -DQ promoters. RF-X mRNA is present in the regulatory mutants, indicating a defect in the synthesis of a functional form of the RF-X protein. Images PMID:2498880

  19. Major histocompatibility complex class I core promoter elements are not essential for transcription in vivo.

    PubMed

    Barbash, Zohar S; Weissman, Jocelyn D; Campbell, John A; Mu, Jie; Singer, Dinah S

    2013-11-01

    The role of core promoter elements in regulating transcription initiation is largely unknown for genes subject to complex regulation. Major histocompatibility complex class I genes are ubiquitously expressed and governed by tissue-specific and hormonal signals. Transcription initiates at multiple sites within the core promoter, which contains elements homologous to the canonical elements CCAAT, TATAA, Sp1 binding site (Sp1BS), and Initiator (Inr). To determine their functions, expression of class I transgenes with individually mutated elements was assessed. Surprisingly, all mutant promoters supported transcription. However, each mutated core promoter element had a distinct effect on expression: CAAT box mutations modulated constitutive expression in nonlymphoid tissues, whereas TATAA-like element mutations dysregulated transcription in lymphoid tissues. Inr mutations aberrantly elevated expression. Sp1BS element mutations resulted in variegated transgene expression. RNA polymerase II binding and histone H3K4me3 patterns correlated with transgene expression; H3K9me3 marks partially correlated. Whereas the wild-type, TATAA-like, and CAAT mutant promoters were activated by gamma interferon, the Sp1 and Inr mutants were repressed, implicating these elements in regulation of hormonal responses. These results lead to the surprising conclusion that no single element is required for promoter activity. Rather, each plays a distinct role in promoter activity, chromatin structure, tissue-specific expression, and extracellular signaling.

  20. Major Histocompatibility Complex Class I Core Promoter Elements Are Not Essential for Transcription in vivo

    PubMed Central

    Barbash, Zohar S.; Weissman, Jocelyn D.; Campbell, John A.; Mu, Jie

    2013-01-01

    The role of core promoter elements in regulating transcription initiation is largely unknown for genes subject to complex regulation. Major histocompatibility complex class I genes are ubiquitously expressed and governed by tissue-specific and hormonal signals. Transcription initiates at multiple sites within the core promoter, which contains elements homologous to the canonical elements CCAAT, TATAA, Sp1 binding site (Sp1BS), and Initiator (Inr). To determine their functions, expression of class I transgenes with individually mutated elements was assessed. Surprisingly, all mutant promoters supported transcription. However, each mutated core promoter element had a distinct effect on expression: CAAT box mutations modulated constitutive expression in nonlymphoid tissues, whereas TATAA-like element mutations dysregulated transcription in lymphoid tissues. Inr mutations aberrantly elevated expression. Sp1BS element mutations resulted in variegated transgene expression. RNA polymerase II binding and histone H3K4me3 patterns correlated with transgene expression; H3K9me3 marks partially correlated. Whereas the wild-type, TATAA-like, and CAAT mutant promoters were activated by gamma interferon, the Sp1 and Inr mutants were repressed, implicating these elements in regulation of hormonal responses. These results lead to the surprising conclusion that no single element is required for promoter activity. Rather, each plays a distinct role in promoter activity, chromatin structure, tissue-specific expression, and extracellular signaling. PMID:24019072

  1. MHC class II polymorphism is associated with a canine SLE-related disease complex.

    PubMed

    Wilbe, Maria; Jokinen, Päivi; Hermanrud, Christina; Kennedy, Lorna J; Strandberg, Erling; Hansson-Hamlin, Helene; Lohi, Hannes; Andersson, Göran

    2009-08-01

    Nova Scotia duck tolling retrievers are predisposed to a SLE-related disease complex including immune-mediated rheumatic disease (IMRD) and steroid-responsive meningitis-arteritis (SRMA). IMRD involves symptoms that resemble those seen in systemic autoimmune rheumatic diseases, such as systemic lupus erythematosus, SLE, or SLE-related diseases, in humans. This disease complex involves persistent lameness, stiffness, mainly after resting, and palpable pain from several joints of extremities. The majority of affected dogs display antinuclear autoantibody (ANA)-reactivity. SRMA is manifested in young dogs with high fever and neck stiffness and can be treated with corticosteroids. We have investigated the possible role of MHC class II as a genetic risk factor in IMRD and SRMA etiology. We performed sequence-based typing of the DLA-DRB1, -DQA1, and -DQB1 class II loci in a total of 176 dogs including 51 IMRD (33 ANA-positive), 49 SRMA cases, and 78 healthy controls (two dogs were both IMRD- and SRMA-affected). Homozygosity for the risk haplotype DRB1*00601/DQA1*005011/DQB1*02001 increased the risk for IMRD (OR = 4.9; ANA-positive IMRD: OR = 7.2) compared with all other genotypes. There was a general heterozygote advantage, homozygotes had OR = 4.4 (ANA-positive IMRD: OR = 8.9) compared with all heterozygotes. The risk haplotype contains the five amino acid epitope RARAA, known as the shared epitope for rheumatoid arthritis. No association was observed for SRMA. We conclude that DLA class II is a highly significant genetic risk factor for ANA-positive IMRD. The results indicate narrow diversity of DLA II haplotypes and identify an IMRD-related risk haplotype, which becomes highly significant in homozygous dogs.

  2. Effect of temperature on the expression of major histocompatibility complex class-I antigens.

    PubMed

    Aboud, M; Segal, S; Priel, E; Blair, D G; O'Hara, B

    1992-06-01

    In the present study we investigated the effect of temperature on MHC class-I gene expression in BALB/C 3T3 cells incubated for 5 days at 34 degrees C, 37 degrees C and 39 degrees C. FACS analysis revealed no significant difference in the cell surface expression of any of the 3 major class-I antigens at 34 degrees C and 37 degrees C. Strikingly, however, when the level of the respective mRNA was determined, only that of the H-2K was comparable at both temperatures, whereas the levels of the H-2D and H-2L mRNA were profoundly higher at 37 degrees C. These data appear to reflect a differential temperature-related transcriptional control of the different class-I genes or a different temperature effect on the stability of their mRNA. The absence of a parallel increase in surface expression of the corresponding H-2D and H-2L antigens may result from some translational or post-translational limiting factors. At 39 degrees C, however, these limiting factors seem to be overcome since the surface expression of all the 3 antigens was remarkably increased although the level of their encoding mRNA was rather lower than in 37 degrees C. This stimulatory effect might be ascribed to heat shock proteins which are known to arise in cells at heat or other stress conditions. They participate in assembly and disassembly of various protein complexes and in transport of certain proteins across intracellular membranes. Such proteins may have arisen in our cells at 39 degrees C and facilitated the intracellular assembly of the class-I molecules and their transport to the cell surface. The possible implication of such heat shock proteins in the anti-tumor effect of hyperthermia is discussed.

  3. 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.

  4. Diacylglycerol kinase α regulates tubular recycling endosome biogenesis and major histocompatibility complex class I recycling.

    PubMed

    Xie, Shuwei; Naslavsky, Naava; Caplan, Steve

    2014-11-14

    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.

  5. 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

  6. Expression in L cells of transfected class I genes from the mouse major histocompatibility complex.

    PubMed Central

    Schepart, B S; Woodward, J G; Palmer, M J; Macchi, M J; Basta, P; McLaughlin-Taylor, E; Frelinger, J A

    1985-01-01

    One of the major surprises of the molecular analysis of major histocompatibility complex (MHC) genes is the large number of class I (K/D)-related sequences in the genome. Both restriction fragment length polymorphisms and cosmid cloning experiments showed them all to be closely linked to the MHC. Until now little information was available concerning either their expression or recognition by the immune system. Here we report that these non-K/D genes can provoke antibody responses and be recognized by cytolytic T cells. Immunization of C3H mice with L cells transfected with class I genomic clones resulted in antisera that reacted preferentially with cells from strain B10.P (the gene donor). Thus, these genes can be expressed by L cells. These products were recognized by cytolytic T cells produced by mixed lymphocyte culture with B10.P stimulators. One gene, represented in clone lambda 3a, was chosen for further analysis. A restriction fragment length polymorphism, detected between B10.P (KpDp) and B10.F(14R) (KbDp) and between B10 (KbDb) and B10.F(13R) (KpDb), has enabled us to map the lambda 3a sequence to the D or Tla region. Restriction endonuclease mapping of the lambda 3a clone shows that the gene is intact and that, although many restriction sites are conserved, the gene in lambda 3a differs from other class I genes. When the lambda 3a clone was transfected into mouse L cells, a new product was expressed. Cells expressing this product (designated L3a cells) were killed by primary D-end-reactive, allospecific cytolytic T lymphocytes. The L3a cells were unreactive with monoclonal antibodies specific for the Kp,Dp,Qa-2, Tla.3, and Tla.5 molecules. Images PMID:2991930

  7. Robust H∞ observer-based control for synchronization of a class of complex dynamical networks

    NASA Astrophysics Data System (ADS)

    Zheng, Hai-Qing; Jing, Yuan-Wei

    2011-06-01

    This paper is concerned with the robust H∞ synchronization problem for a class of complex dynamical networks by applying the observer-based control. The proposed feedback control scheme is developed to ensure the asymptotic stability of the augmented system, to reconstruct the non-measurable state variables of each node and to improve the H∞ performance related to the synchronization error and observation error despite the external disturbance. Based on the Lyapunov stability theory, a synchronization criterion is obtained under which the controlled network can be robustly stabilized onto a desired state with a guaranteed H∞ performance. The controller and the observer gains can be given by the feasible solutions of a set of linear matrix inequalities (LMIs). The effectiveness of the proposed control scheme is demonstrated by a numerical example through simulation.

  8. H ∞ Cluster Synchronization for a Class of Neutral Complex Dynamical Networks with Markovian Switching

    PubMed Central

    2014-01-01

    H ∞ cluster synchronization problem for a class of neutral complex dynamical networks (NCDNs) with Markovian switching is investigated in this paper. Both the retarded and neutral delays are considered to be interval mode dependent and time varying. The concept of H ∞ cluster synchronization is proposed to quantify the attenuation level of synchronization error dynamics against the exogenous disturbance of the NCDNs. Based on a novel Lyapunov functional, by employing some integral inequalities and the nature of convex combination, mode delay-range-dependent H ∞ cluster synchronization criteria are derived in the form of linear matrix inequalities which depend not only on the disturbance attenuation but also on the initial values of the NCDNs. Finally, numerical examples are given to demonstrate the feasibility and effectiveness of the proposed theoretical results. PMID:24892088

  9. Characterisation of major histocompatibility complex class I genes in Japanese Ranidae frogs.

    PubMed

    Lau, Quintin; Igawa, Takeshi; Komaki, Shohei; Satta, Yoko

    2016-11-01

    The major histocompatibility complex (MHC) is a key component of adaptive immunity in all jawed vertebrates, and understanding the evolutionary mechanisms that have shaped these genes in amphibians, one of the earliest terrestrial tetrapods, is important. We characterised MHC class I variation in three common Japanese Rana species (Rana japonica, Rana ornativentris and Rana tagoi tagoi) and identified a total of 60 variants from 21 individuals. We also found evolutionary signatures of gene duplication, recombination and balancing selection (including trans-species polymorphism), all of which drive increased MHC diversity. A unique feature of MHC class I from these three Ranidae species includes low synonymous differences per site (d S) within species, which we attribute to a more recent diversification of these sequences or recent gene duplication. The resulting higher d N/d S ratio relative to other anurans studied could be related to stronger selection pressure at peptide binding sites. This is one of the first studies to investigate MHC in Japanese amphibians and permits further exploration of the polygenetic factors associated with resistance to infectious diseases.

  10. Major histocompatibility complex class I genes of the coelacanth Latimeria chalumnae.

    PubMed

    Betz, U A; Mayer, W E; Klein, J

    1994-11-08

    The coelacanth fish Latimeria chalumnae is the sole surviving species of a phylogenetic lineage that was founded more than 400 million years ago and that has changed morphologically very little since that time. Little is known about the molecular evolution of this "living fossil," considered by some taxonomists to be the closest living relative of tetrapods. Here we describe the isolation and characterization of L. chalumnae major histocompatibility complex (MHC) class I genes. The exon-intron organization of these genes is the same as that of their mammalian counterparts. The genes fall into four families, which we designate Lach-UA through Lach-UD. There are multiple loci in all of the families. Genes of the first two families are transcribed. The Lach-UA family bears the characteristics of functional, polymorphic class I genes; the other three families may be represented by nonclassical genes. All the Lach loci arose by duplication from an ancestral gene after the foundation of the coelacanth lineage. Intergenic variation is highest at positions corresponding to the mammalian peptide-binding region. The closest relatives of the Lach genes among the MHC genes sequenced thus far are those of the amphibian Xenopus.

  11. Molecular characterization of the Pb recombination hotspot in the mouse major histocompatibility complex class II region.

    PubMed

    Isobe, Taku; Yoshino, Masayasu; Mizuno, Ken-Ichi; Lindahl, Kirsten Fischer; Koide, Tsuyoshi; Gaudieri, Silvana; Gojobori, Takashi; Shiroishi, Toshihiko

    2002-08-01

    In the mouse major histocompatibility complex (MHC) class II region, meiotic recombination breakpoints are clustered in four specific sites known as hotspots. Here we reveal the primary structure of a hotspot near the Pb gene. A total of 12 crossover points were found to be confined to a 15-kb DNA segment of the Pb pseudogene. Moreover, the crossover points are concentrated in a 341-bp segment, which includes a part of exon 4 and intron 4 of the Pb gene. All four MHC hotspots appear to be located within genes or at the 3' end of genes, contrasting with characterized hotspots in budding yeast, which are mostly located at the 5'-promoter regions of genes. The Pb hotspot has several consensus motifs, an octamer transcription factor-binding sequence, the B-motif-like transcription factor-binding sequence, and tandem repeats of tetramer sequence-all of which are shared by the other three hotspots. Systematic analysis of the public database demonstrated that the full motif set occurs rarely in the nucleotide sequence of the entire MHC class II region. All results suggest that the motif set has an indispensable role in determining their site specificity.

  12. Selective class II HDAC inhibitors impair myogenesis by modulating the stability and activity of HDAC–MEF2 complexes

    PubMed Central

    Nebbioso, Angela; Manzo, Fabio; Miceli, Marco; Conte, Mariarosaria; Manente, Lucrezia; Baldi, Alfonso; De Luca, Antonio; Rotili, Dante; Valente, Sergio; Mai, Antonello; Usiello, Alessandro; Gronemeyer, Hinrich; Altucci, Lucia

    2009-01-01

    Histone deacetylase (HDAC) inhibitors are promising new epi-drugs, but the presence of both class I and class II enzymes in HDAC complexes precludes a detailed elucidation of the individual HDAC functions. By using the class II-specific HDAC inhibitor MC1568, we separated class I- and class II-dependent effects and defined the roles of class II enzymes in muscle differentiation in cultured cells and in vivo. MC1568 arrests myogenesis by (i) decreasing myocyte enhancer factor 2D (MEF2D) expression, (ii) by stabilizing the HDAC4–HDAC3–MEF2D complex, and (iii) paradoxically, by inhibiting differentiation-induced MEF2D acetylation. In vivo MC1568 shows an apparent tissue-selective HDAC inhibition. In skeletal muscle and heart, MC1568 inhibits the activity of HDAC4 and HDAC5 without affecting HDAC3 activity, thereby leaving MEF2–HDAC complexes in a repressed state. Our results suggest that HDAC class II-selective inhibitors might have a therapeutic potential for the treatment of muscle and heart diseases. PMID:19498465

  13. Localisation of deformations of the midfacial complex in subjects with class III malocclusions employing thin-plate spline analysis

    PubMed Central

    SINGH, G. D.; McNAMARA JR, J. A.; LOZANOFF, S.

    1997-01-01

    This study determines deformations of the midface that contribute to a class III appearance, employing thin-plate spline analysis. A total of 135 lateral cephalographs of prepubertal children of European-American descent with either class III malocclusions or a class I molar occlusion were compared. The cephalographs were traced and checked, and 7 homologous landmarks of the midface were identified and digitised. The data sets were scaled to an equivalent size and subjected to Procrustes analysis. These statistical tests indicated significant differences (P<0.05) between the averaged class I and class III morphologies. Thin-plate spline analysis indicated that both affine and nonaffine transformations contribute towards the total spline for the averaged midfacial configuration. For nonaffine transformations, partial warp 3 had the highest magnitude, indicating the large scale deformations of the midfacial configuration. These deformations affected the palatal landmarks, and were associated with compression of the midfacial complex in the anteroposterior plane predominantly. Partial warp 4 produced some vertical compression of the posterior aspect of the midfacial complex whereas partial warps 1 and 2 indicated localised shape changes of the maxillary alveolus region. Large spatial-scale deformations therefore affect the midfacial complex in an anteroposterior axis, in combination with vertical compression and localised distortions. These deformations may represent a developmental diminution of the palatal complex anteroposteriorly that, allied with vertical shortening of midfacial height posteriorly, results in class III malocclusions with a retrusive midfacial profile. PMID:9449078

  14. 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.

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

    PubMed

    Sándor, Bulcsú; Gros, Claudius

    2015-07-22

    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.

  16. 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

  17. Detection of autoreactive CD4 T cells using major histocompatibility complex class II dextramers

    PubMed Central

    2011-01-01

    Background Tetramers are useful tools to enumerate the frequencies of antigen-specific T cells. However, unlike CD8 T cells, CD4 T cells - especially self-reactive cells - are challenging to detect with major histocompatibility complex (MHC) class II tetramers because of low frequencies and low affinities of their T cell receptors to MHC-peptide complexes. Here, we report the use of fluorescent multimers, designated MHC dextramers that contain a large number of peptide-MHC complexes per reagent. Results The utility of MHC dextramers was evaluated in three autoimmune disease models: 1) proteolipid protein (PLP) 139-151-induced experimental autoimmune encephalomyelitis in SJL/J (H-2s) mice; 2) myelin oligodendrocyte glycoprotein (MOG) 35-55-induced experimental autoimmune encephalomyelitis in C57Bl/6 (H-2b) mice; and 3) cardiac myosin heavy chain (Myhc)-α 334-352-induced experimental autoimmune myocarditis in A/J (H-2a) mice. Flow cytometrically, we demonstrate that IAs/PLP 139-151, IAb/MOG 35-55 and IAk/Myhc-α 334-352 dextramers detect the antigen-sensitized cells with specificity, and with a detection sensitivity significantly higher than that achieved with conventional tetramers. Furthermore, we show that binding of dextramers, but not tetramers, is less dependent on the activation status of cells, permitting enumeration of antigen-specific cells ex vivo. Conclusions The data suggest that MHC dextramers are useful tools to track the generation and functionalities of self-reactive CD4 cells in various experimental systems. PMID:21767394

  18. Major histocompatibility complex class I and class II alleles may confer susceptibility to or protection against morphea: findings from the Morphea in Adults and Children cohort.

    PubMed

    Jacobe, Heidi; Ahn, Chul; Arnett, Frank C; Reveille, John D

    2014-11-01

    To determine the HLA class I and class II alleles of the human major histocompatibility complex showing an association with morphea (localized scleroderma) in the Morphea in Adults and Children (MAC) cohort, using a nested case-control association study. Patients with morphea were identified from the MAC cohort, and matched controls were obtained from the National Institutes of Health/National Institute of Arthritis and Musculoskeletal and Skin Diseases Scleroderma Family Registry and DNA Repository and from the Division of Rheumatology at the University of Texas Health Science Center at Houston. HLA class II genotyping and single-strand conformational polymorphism typing were performed to identify HLA-A, B, and C alleles. Associations between HLA class I and class II alleles and morphea, as well as its subphenotypes, were determined. Two hundred eleven patients with morphea and 726 matched controls were available for HLA class I typing, and 158 patients with morphea and 1,008 matched controls were available for HLA class II typing. The strongest associations were found with DRB1*04:04 (odds ratio [OR] 2.3, 95% confidence interval [95% CI] 1.4-4.0, P = 0.002), and HLA-B*37 conferred the highest OR among the class I alleles (OR 3.2, 95% CI 1.5-6.5, P = 0.001). Comparison of the risk allele profile in this cohort with the risk alleles previously identified in patients with systemic sclerosis, determined using the same methods and same control population, revealed one allele in common, DRB*04:04. These results demonstrate that specific HLA class I and class II alleles are associated with morphea and are also likely to be associated with generalized and linear subtypes of morphea. The morphea-associated alleles are different from those found in scleroderma, suggesting that morphea is immunogenetically distinct. Risk alleles in morphea are also associated with conditions such as rheumatoid arthritis (RA) and other autoimmune conditions. Population-based studies have

  19. Evolution of the major histocompatibility complex: isolation of class II A cDNA clones from the cartilaginous fish.

    PubMed Central

    Kasahara, M; Vazquez, M; Sato, K; McKinney, E C; Flajnik, M F

    1992-01-01

    Along with the T-cell receptor and immunoglobulin, the major histocompatibility complex (MHC) plays a key role in mounting immune responses to foreign antigen. To gain insights into the evolution of the MHC, class II A cDNA clones were isolated from nurse sharks, a member of the class of cartilaginous fish. Two closely related cDNA clones, which might encode allelic products, were identified; of the three amino acid substitutions found in the alpha 1 domain, two were located at positions postulated to interact with processed peptides. The deduced nurse shark MHC class II alpha chains showed conspicuous structural similarity to their mammalian counterparts. Isolation of cDNA clones encoding typical MHC class II alpha chains was unexpected since no direct evidence for T-cell-mediated immune responses has been obtained in the cartilaginous fish. The cartilaginous fish is phylogenetically the most primitive class of vertebrates from which any MHC gene has been isolated. PMID:1495958

  20. A family of MHC class I-like genes located in the vicinity of the mouse leukocyte receptor complex

    PubMed Central

    Kasahara, Masanori; Watanabe, Yutaka; Sumasu, Motoko; Nagata, Taeko

    2002-01-01

    Some members of the major histocompatibility complex (MHC) class I gene family are encoded outside the MHC. Here we describe a family of mouse class I-like genes mapping to the vicinity of the leukocyte receptor complex (LRC) on chromosome 7. This family, which we call Mill (MHC class I-like located near the LRC), has two members designated Mill1 and Mill2. Both genes are predicted to encode membrane glycoproteins with domain organization essentially similar to that of MHC class I heavy chains. The following features of Mill are noteworthy. (i) The deduced MILL proteins lack most of the residues known to be involved in the docking of peptides in classical MHC class I molecules. (ii) Among the known members of the class I gene family, MILL1 and MILL2 are related most closely to MICA/MICB encoded in the human MHC. (iii) Unlike all other known members of the class I gene family, Mill1 and Mill2 have an exon between those coding for the signal peptide and the α1 domain. (iv) Mill1 has a more restricted expression profile than Mill2. (v) The gene orthologous to Mill1 or Mill2 apparently is absent in the human. (vi) Mill1 and Mill2 show a limited degree of polymorphism in laboratory mice. The observation that the Mill family is related most closely to the MIC family, together with its apparent absence in the human, suggests its involvement in innate immunity. PMID:12370446

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

    SciTech Connect

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

    1988-04-01

    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.

  2. Superalkali@C60-superhalogen: Structure and nonlinear optical properties of a new class of endofullerene complexes

    NASA Astrophysics Data System (ADS)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj

    2017-08-01

    We propose a new class of endofullerene complexes by encapsulating superalkali species (viz. FLi2, OLi3 and NLi4) within C60 and then interacting with superhalogens (viz. BF4, BCl4 and BBr4). Our DFT calculations reveal that all M@C60-BF4 (M = FLi2 < OLi3 < NLi4) endofullerene complexes are stable against complexation and deencapsulation. The first order mean hyperpolarizability (βo) values decrease with the increase in the size of encapsulated superalkalis but increase with the increase in the size of superhalogen. The trend of βo values has been explained by TDDFT calculated parameters for crucial electronic transitions of endofullerene complexes.

  3. 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.

  4. 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.

  5. Alkali-activated complex binders from class C fly ash and Ca-containing admixtures.

    PubMed

    Guo, Xiaolu; Shi, Huisheng; Chen, Liming; Dick, Warren A

    2010-01-15

    Processes that maximize utilization of industrial solid wastes are greatly needed. Sodium hydroxide and sodium silicate solution were used to create alkali-activated complex binders (AACBs) from class C fly ash (CFA) and other Ca-containing admixtures including Portland cement (PC), flue gas desulfurization gypsum (FGDG), and water treatment residual (WTR). Specimens made only from CFA (CFA100), or the same fly ash mixed with 40 wt% PC (CFA60-PC40), with 10 wt% FGDG (CFA90-FGDG10), or with 10 wt% WTR (CFA90-WTR10) had better mechanical performance compared to binders using other mix ratios. The maximum compressive strength of specimens reached 80.0 MPa. Geopolymeric gel, sodium polysilicate zeolite, and hydrated products coexist when AACB reactions occur. Ca from CFA, PC, and WTR precipitated as Ca(OH)(2), bonded in geopolymers to obtain charge balance, or reacted with dissolved silicate and aluminate species to form calcium silicate hydrate (C-S-H) gel. However, Ca from FGDG probably reacted with dissolved silicate and aluminate species to form ettringite. Utilization of CFA and Ca-containing admixtures in AACB is feasible. These binders may be widely utilized in various applications such as in building materials and for solidification/stabilization of other wastes, thus making the wastes more environmentally benign.

  6. 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.

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

    SciTech Connect

    Ahmed, A.R. Center for Blood Research, Boston, MA American Red Cross Blood Services-Northeast Region, Dedham, MA ); Wagner, R.; Khatri, K.; Notani, G.; Awdeh, Z.; Alper, C.A. ); Yunis, E.J. American Red Cross Blood Services-Northeast Region, Dedham, MA )

    1991-06-01

    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) halotypes 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. 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 amd 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.

  8. 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.

  9. 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.

  10. Genetic complexity of regulatory mutants defective for HLA class II gene expression

    SciTech Connect

    Seidl, C.; Saraiya, C.; Osterweil, Z.; Fu, Y. Ping; Lee, J.S. )

    1992-03-01

    MHC (called HLA in man) class II genes play an essential role in cell-mediated immunity. Absence of HLA class II Ag on B lymphocytes is the basis of some congenital immunodeficiencies (CID). The authors have studied CID by generating transient heterokaryons from cell lines of such patients, and report that the mutations fall into four complementation groups. In addition, fusions with the HLA class II deletion mutant 721.180 indicate that the genetic defects for each group in HLA class II expression map outside the HLA class II region. A small HLA-DRA promoter fragment is sufficient to drive expression of a reporter gene in normal B cell lines, but expression from the same construct is clearly reduced in mutant cell lines representative of all four complementation groups. This confirms earlier results that indicate defective transcription of HLA class II genes in the class II[sup [minus

  11. 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.

  12. The role of "indirect" recognition in initiating rejection of skin grafts from major histocompatibility complex class II-deficient mice.

    PubMed Central

    Auchincloss, H; Lee, R; Shea, S; Markowitz, J S; Grusby, M J; Glimcher, L H

    1993-01-01

    In vitro studies have revealed several pathways by which T cells can respond to alloantigens, including CD4+ direct responses to allogeneic class II antigens, CD8+ direct responses to allogeneic class I antigens, and CD4+ "indirect" responses to peptides of alloantigens presented in association with responder class II molecules. In vivo studies of skin graft rejection, however, have so far provided clear evidence for the contribution of only the two direct pathways and not for indirect recognition. We have used major histocompatibility complex class II-deficient mice as donors to test the role of indirect recognition in rejection of skin grafts. Class II-deficient skin was always rejected without delay by normal recipients. Removal of recipient CD8+ cells (to leave the animals dependent on CD4+ function) or depletion of recipient CD4+ cells revealed that CD4+ cells were usually involved and sometimes absolutely required in this rapid rejection. Since the donor grafts lacked class II antigens, the CD4+ cells must have recognized donor antigens presented in association with recipient class II molecules. These results therefore indicate that indirect recognition can initiate rapid skin graft rejection. PMID:8475083

  13. Characterization and Physiological Function of Class I Low-Molecular-Mass, Heat-Shock Protein Complex in Soybean.

    PubMed

    Jinn, T. L.; Chen, Y. M.; Lin, C. Y.

    1995-06-01

    Examination of an ammonium sulfate-enriched fraction (70-100% saturation) of heat-shock proteins (HSPs) by nondenaturing polyacrylamide gel electrophoresis revealed the presence of a high molecular mass complex (280 kD) in soybean (Glycine max) seedlings. This complex cross-reacted with antibodies raised against soybean class I low-molecular-mass (LMW) HSPs. Dissociation of the complex by denaturing polyacrylamide gel electrophoresis showed the complex to contain at least 15 polypeptides of the 15-to 18-kD class I LMW HSPs that could be detected by staining, radiolabeling, and western blotting. A similar LMW-HSP complex was observed in mung bean (Vigna radiata L.; 295 kD), in pea (Pisum sativum L.; 270 kD), and in rice (Oryza sativa L.; 310 kD). The complex was stable under high salt conditions (250 mM KCI), and the integrity was not affected by 1% Nonidet P-40 and 3 [mu]g/ML RNase treatment. The size of the isolated HSP complex in vitro was conserved to 55[deg]C; however, starting at 37.5[deg]C, it changed to higher molecular forms in the presence of soluble proteins. The isolated HSP complex was able to protect up to 75% of the soluble proteins from heat denaturation in vitro.

  14. 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.

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

    PubMed Central

    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

    2016-01-01

    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/μm2. 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

  16. Health status transitions in community-living elderly with complex care needs: a latent class approach

    PubMed Central

    Lafortune, Louise; Béland, François; Bergman, Howard; Ankri, Joël

    2009-01-01

    Background For older persons with complex care needs, accounting for the variability and interdependency in how health dimensions manifest themselves is necessary to understand the dynamic of health status. Our objective is to test the hypothesis that a latent classification can capture this heterogeneity in a population of frail elderly persons living in the community. Based on a person-centered approach, the classification corresponds to substantively meaningful groups of individuals who present with a comparable constellation of health problems. Methods Using data collected for the SIPA project, a system of integrated care for frail older people (n = 1164), we performed latent class analyses to identify homogenous categories of health status (i.e. health profiles) based on 17 indicators of prevalent health problems (chronic conditions; depression; cognition; functional and sensory limitations; instrumental, mobility and personal care disability) Then, we conducted latent transition analyses to study change in profile membership over 2 consecutive periods of 12 and 10 months, respectively. We modeled competing risks for mortality and lost to follow-up as absorbing states to avoid attrition biases. Results We identified four health profiles that distinguish the physical and cognitive dimensions of health and capture severity along the disability dimension. The profiles are stable over time and robust to mortality and lost to follow-up attrition. The differentiated and gender-specific patterns of transition probabilities demonstrate the profiles' sensitivity to change in health status and unmasked the differential relationship of physical and cognitive domains with progression in disability. Conclusion Our approach may prove useful at organization and policy levels where many issues call for classification of individuals into pragmatically meaningful groups. In dealing with attrition biases, our analytical strategy could provide critical information for the

  17. Major Histocompatibility Complex Class I Chain-Related A (MICA) Molecules: Relevance in Solid Organ Transplantation

    PubMed Central

    Baranwal, Ajay Kumar; Mehra, Narinder K.

    2017-01-01

    An ever growing number of reports on graft rejection and/or failure even with good HLA matches have highlighted an important role of non-HLA antigens in influencing allograft immunity. The list of non-HLA antigens that have been implicated in graft rejection in different types of organ transplantation has already grown long. Of these, the Major Histocompatibility Complex class I chain-related molecule A (MICA) is one of the most polymorphic and extensively studied non-HLA antigenic targets especially in the kidney transplantation. Humoral response to MICA antigens has repeatedly been associated with lower graft survival and an increased risk of acute and chronic rejection following kidney and liver transplantation with few studies showing conflicting results. Although there are clear indications of MICA antibodies being associated with adverse graft outcome, a definitive consensus on this relationship has not been arrived yet. Furthermore, only a few studies have dealt with the impact of MICA donor-specific antibodies as compared to those that are not donor specific on graft outcome. In addition to the membrane bound form, a soluble isoform of MICA (sMICA), which has the potential to engage the natural killer cell-activating receptor NKG2D resulting in endocytosis and degradation of receptor–ligand interaction complex leading to suppression of NKG2D-mediated host innate immunity, has been a subject of intense discussion. Most studies on sMICA have been directed toward understanding their influence on tumor growth, with limited literature focusing its role in transplant biology. Furthermore, a unique dimorphism (methionine to valine) at position 129 in the α2 domain categorizes MICA alleles into strong (MICA-129 met) and weak (MICA-129 val) binders of NKG2D receptor depending on whether they have methionine or valine at this position. Although the implications of MICA 129 dimorphism have been highlighted in hematopoietic stem cell transplantation, its role in

  18. Species specificity and augmentation of responses to class II major histocompatibility complex molecules in human CD4 transgenic mice

    PubMed Central

    1992-01-01

    Murine T cell responses to human class II major histocompatibility complex (MHC) molecules were shown to be a minimum of 20-70-fold lower than responses to allogeneic molecules. Transgenic mice expressing slightly below normal (75-95%) or very high (250-380%) cell surface levels of human CD4 were utilized to determine whether this was due to a species-specific interaction between murine CD4 and class II molecules. Human CD4 was shown to function in signal transduction events in murine T cells based on the ability of anti-human CD4 antibody to synergize with suboptimal doses of anti-murine CD3 antibody in stimulating T cell proliferation. In mice expressing lower levels of human CD4, T cell responses to human class II molecules were enhanced up to threefold, whereas allogeneic responses were unaltered. In mice expressing high levels of human CD4, responses to human class II molecules were enhanced at least 10-fold, whereas allogeneic responses were between one and three times the level of normal responses. The relatively greater enhancement of the response to human class II molecules in both lines argues for a preferential interaction between human CD4 and human class II molecules. In mice expressing lower levels of human CD4, responses to human class II molecules were blocked by antibodies to CD4 of either species, indicating participation by both molecules. In mice expressing high levels of human CD4, responses to both human and murine class II molecules were almost completely blocked with anti-human CD4 antibody, whereas anti-murine CD4 antibody had no effect. However, anti-murine CD4 continued to synergize with anti-CD3 in stimulating T cell proliferation in these mice. Thus, overexpression of human CD4 selectively impaired the ability of murine CD4 to assist in the process of antigen recognition. The ability of human CD4 to support a strong allogeneic response under these conditions indicates that this molecule can interact with murine class II molecules to a

  19. 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…

  20. [Class II malocclusion: some aspects of diagnostics and complex orthodontic and surgical treatment].

    PubMed

    Zorich, M E; Iatskevich, O S; Ivanov, S Iu; Muraev, A A

    2014-01-01

    Class II malocclusions are of interest to the practicing orthodontists since they constitute a significant percentage of the cases they treat. The process of establishing a treatment plan requires an assessment of therapeutic modifiability. The purpose of this article is to provide a perspective on the characteristics, development, etiology and broad treatment consideration in Class II malocclusions.

  1. 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…

  2. Trafficking of major histocompatibility complex class II molecules through intracellular compartments containing HLA-DM.

    PubMed

    Robbins, N F; Hammond, C; Denzin, L K; Pan, M; Cresswell, P

    1996-01-01

    The endosomal site(s) where MHC class II molecules become competent to bind antigenic peptide has not been completely characterized. We identified endocytic compartments through which newly synthesized MHC class II molecules move prior to their expression on the plasma membrane. The compartments co-sediment with lysosomes in the most dense regions of Percoll gradients. The appearance of proteolytic fragments of the invariant chain (I chain), namely leupeptin-induced proteins (LIPs) and class-II-associated invariant chain peptides (CLIP), in this region of the gradient suggests that the release of MHC class II molecules from I chain association occurs within these vesicles. The formation of SDS-stable alpha beta dimers indicated that MHC class II molecules contained within these compartments are receptive to peptide binding. A majority of the HLA-DM protein was found in the same region of the Percoll gradient, consistent with its established function in MHC class-II-restricted antigen presentation. Immunoelectron micrographs of dense-sedimenting compartments indicated that I chain, MHC class II, and DM molecules are contained within both multivesicular and multilamellar vesicles. The final stages of I chain dissociation from MHC class II molecules and DM-mediated peptide loading probably occur in these compartments.

  3. 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…

  4. 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

  5. Human epidermal Langerhans cells cointernalize by receptor-mediated endocytosis "nonclassical" major histocompatibility complex class I molecules (T6 antigens) and class II molecules (HLA-DR antigens).

    PubMed Central

    Hanau, D; Fabre, M; Schmitt, D A; Garaud, J C; Pauly, G; Tongio, M M; Mayer, S; Cazenave, J P

    1987-01-01

    HLA-DR and T6 surface antigens are expressed only by Langerhans cells and indeterminate cells in normal human epidermis. We have previously demonstrated that T6 antigens are internalized in Langerhans cells and indeterminate cells by receptor-mediated endocytosis. This process is induced by the binding of BL6, a monoclonal antibody directed against T6 antigens. In the present study, using a monoclonal antibody directed against HLA-DR antigens, on human epidermal cells in suspension, we show that the surface HLA-DR antigens are also internalized by receptor-mediated endocytosis in Langerhans and indeterminate cells. Moreover, using immunogold double labeling, we demonstrate that T6 and HLA-DR antigens are internalized through common coated regions of the membrane of Langerhans or indeterminate cells. The receptor-mediated endocytosis that is induced involves coated pits and vesicles, receptosomes, lysosomes, and also, in Langerhans cells, the Birbeck granules. Thus, T6 antigens, which are considered to be "unusual" or "nonclassical" major histocompatibility complex class I molecules, and the major histocompatibility complex class II molecules, HLA-DR, are internalized in Langerhans and indeterminate cells through common receptor-mediated endocytosis organelles. Images PMID:3106979

  6. 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.

  7. Expression of major histocompatibility complex class I antigens as a strategy for the potentiation of immune recognition of tumor cells.

    PubMed

    Tanaka, K; Hayashi, H; Hamada, C; Khoury, G; Jay, G

    1986-11-01

    Like many primary tumors, human adenovirus type 12 (Ad12)-transformed mouse cells express greatly reduced levels of the major histocompatibility complex (MHC) class I antigens and are highly tumorigenic in immunocompetent hosts. Expression of a transfected class I gene by these cells can abrogate their tumorigenicity. Both the K and the L class I genes can suppress the malignant phenotype. Previous studies showed that interferon can induce class I gene expression in certain Ad12-transformed cells and can suppress their tumorigenic phenotype. We now demonstrate that preimmunization of mice with a nontumorigenic dose of interferon-treated Ad12-transformed tumor cells can afford protection against a subsequent challenge by a tumorigenic dose of untreated Ad12-transformed tumor cells. Similar immunity can also be induced by using cells transfected with the K gene, and the observed protection appears specific to Ad12-transformed cells. Significant protection can be achieved even if immunization is provided subsequent to the tumor challenge. Since increasing numbers of human tumors have been found to have reduced levels of MHC class I antigens, the prospect of therapy by immunization with the parental tumor cells that have been manipulated to induce class I gene expression offers an attractive experimental model.

  8. Determinant selection of major histocompatibility complex class I- restricted antigenic peptides is explained by class I-peptide affinity and is strongly influenced by nondominant anchor residues

    PubMed Central

    1994-01-01

    The contribution of major histocompatibility complex (MHC) class I- peptide affinity to immunodominance of particular peptide antigens (Ags) in the class I-restricted cytotoxic T lymphocyte (CTL) response is not clearly established. Therefore, we have compared the H-2Kb- restricted binding and presentation of the immunodominant ovalbumin (OVA)257-264 (SIINFEKL) determinant to that of a subdominant OVA determinant OVA55-62 (KVVRFDKL). Immunodominance of OVA257-264 was not attributable to the specific T cell repertoire but correlated instead with more efficient Ag presentation. This enhanced Ag presentation could be accounted for by the higher affinity of Kb/OVA257-264 compared with Kb/OVA55-62 despite the presence of a conserved Kb-binding motif in both peptides. Kinetic binding studies using purified soluble H-2Kb molecules (Kbs) and biosensor techniques indicated that the Kon for association of OVA257-264-C6 and Kbs at 25 degrees C was integral of 10- fold faster (5.9 x 10(3) M-1 s-1 versus 6.5 x 10(2) M-1 s-1), and the Koff approximately twofold slower (9.1 x 10(-6) s-1 versus 1.6 x 10(-5) s-1), than the rate constants for interaction of OVA55-62-C6 and Kbs. The association of these peptides with Kb was significantly influenced by multiple residues at presumed nonanchor sites within the peptide sequence. The contribution of each peptide residue to Kb-binding was dependent upon the sequence context and the summed contributions were not additive. Thus the affinity of MHC class I-peptide binding is a critical factor controlling presentation of peptide Ag and immunodominance in the class I-restricted CTL response. PMID:7523572

  9. 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.

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

    PubMed Central

    Li, Hongmin; Zhao, Yiwei; Guo, Yi; Li, Zhong; Eisele, Leslie; Mourad, Walid

    2014-01-01

    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 Vβ 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, Zn2+ 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 Zn2+. However, in the presence of Zn2+, a dimerized MAM/HLA-DR1/HA complex can arise through the Zn2+-induced DR1 dimer. In the presence of Zn2+, cooperative binding of MAM to the DR1 dimer was also observed. PMID:17166841

  11. 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

  12. Chromosomal organization of the human major histocompatibility complex class I gene family

    SciTech Connect

    Koller, B.H.; Geraghty, D.E.; DeMars, R.; Duvick, L.; Rich, S.S.; Orr, H.T.

    1989-02-01

    17 HLA class I genes have been isolated from the genome of B-lymphoblastoid cell line 721. Sequence analysis and transfection studies indicate that three genes, in addition to those encoding the HLA-A, -B, and -C antigens can direct the synthesis of a class I alpha protein (4, 5, 21). Using gene-specific DNA probes to analyze the presence of restriction fragment-length polymorphisms within a large pedigree and in panel of HLA deletion mutant cell lines, we show here that two of these genes, designated HLA-G and HLA-F, are located on the short arm of chromosome 6 telomeric to the HLA-A locus. The third expressed non-A, -B, and -C class I gene, HLA-E, is located between HLA-A and HLA-C (4). In addition, the remaining 11 class I pseudogenes and gene fragments are localized relative to established markers on chromosome 6p.

  13. Human class I major histocompatibility complex alleles determine central nervous system injury versus repair.

    PubMed

    Wootla, Bharath; Denic, Aleksandar; Watzlawik, Jens O; Warrington, Arthur E; Zoecklein, Laurie J; Papke-Norton, Louisa M; David, Chella; Rodriguez, Moses

    2016-11-17

    We investigated the role of human HLA class I molecules in persistent central nervous system (CNS) injury versus repair following virus infection of the CNS. Human class I A11(+) and B27(+) transgenic human beta-2 microglobulin positive (Hβ2m(+)) mice of the H-2 (b) background were generated on a combined class I-deficient (mouse beta-2 microglobulin deficient, β2m(0)) and class II-deficient (mouse Aβ(0)) phenotype. Intracranial infection with Theiler's murine encephalomyelitis virus (TMEV) in susceptible SJL mice results in acute encephalitis with prominent injury in the hippocampus, striatum, and cortex. Following infection with TMEV, a picornavirus, the Aβ(0).β2m(0) mice lacking active immune responses died within 18 to 21 days post-infection. These mice showed severe encephalomyelitis due to rapid replication of the viral genome. In contrast, transgenic Hβ2m mice with insertion of a single human class I MHC gene in the absence of human or mouse class II survived the acute infection. Both A11(+) and B27(+) mice significantly controlled virus RNA expression by 45 days and did not develop late-onset spinal cord demyelination. By 45 days post-infection (DPI), B27(+) transgenic mice showed almost complete repair of the virus-induced brain injury, but A11(+) mice conversely showed persistent severe hippocampal and cortical injury. The findings support the hypothesis that the expression of a single human class I MHC molecule, independent of persistent virus infection, influences the extent of sub frequent chronic neuronal injury or repair in the absence of a class II MHC immune response.

  14. Reassociation with beta 2-microglobulin is necessary for Db class I major histocompatibility complex binding of an exogenous influenza peptide.

    PubMed Central

    Rock, K L; Gamble, S; Rothstein, L; Benacerraf, B

    1991-01-01

    A synthetic peptide corresponding to residues 365-380 of the influenza nucleoprotein (NP365-380) has been previously shown to associate with class I major histocompatibility complex-encoded molecules and to stimulate cytotoxic T lymphocytes [Townsend, A. R. M., Rothbard, J., Gotch, F. M., Bahadur, G., Wraith, D. & McMichael, A. J. (1986) Cell 44, 959-968]. We find that intact Db class I heterodimers on the cell surface are unreceptive to binding this antigen. However, NP365-380 readily associates with Db molecules on the plasma membrane in the presence of exogenous beta 2-microglobulin. In addition, there is a second pathway through which this peptide associates with class I molecules that requires energy and de novo protein synthesis. These findings have implications for maintaining the immunological identity of cells and for the use of peptides as vaccines for priming cytolytic T-cell immunity. Images PMID:1986378

  15. Transcription of a subset of human class II major histocompatibility complex genes is regulated by a nucleoprotein complex that contains c-fos or an antigenically related protein.

    PubMed Central

    Ono, S J; Bazil, V; Levi, B Z; Ozato, K; Strominger, J L

    1991-01-01

    Transcriptional regulation of the human major histocompatibility complex class II genes requires at least two upstream elements, the X and Y boxes, located in the -50- to -150-base-pair region of all class II promoters. The DRA and DPB promoters contain phorbol ester-responsive elements overlapping the 3' side of their X boxes. Mutation of this sequence down-regulates the efficiency of the DRA promoter, suggesting that a positive regulator(s) binds to this site. In this report, anti-sense c-fos RNA and an anti-c-fos antibody were used to show that the product of the protooncogene c-fos or an antigenically related protein is a component of a complex that binds to the X box and is required for maximal transcription from the DRA and DPB promoters. As c-fos (or its related proteins) cannot bind alone to DNA, these results suggest that it may dimerize with other members of the JUN/AP-1 family, such as hXBP1, to participate in the activation of a subset of class II major histocompatibility complex genes. Images PMID:1709740

  16. THE 1.4 Å CRYSTAL STRUCTURE OF THE CLASS D β-LACTAMASE OXA-1 COMPLEXED WITH DORIPENEM

    PubMed Central

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

    2009-01-01

    The clinical efficacy of carbapenem antibiotics depends on their resistance to the hydrolytic action of β-lactamase enzymes. The structure of the class D β-lactamase OXA-1 as an acyl-complex with the carbapenem doripenem was determined to 1.4 Å resolution. Unlike most class A and class C carbapenem complexes, the acyl carbonyl oxygen in OXA-1/doripenem 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 hydrogen bonds to the alcohol of the 6α-hydroxyethyl moiety of doripenem. The carboxylate attached to the β-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 β-lactamase/β-lactam complexes (eg. 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 Δ 1 tautomer. These findings provide important insights into the role that carbapenems may have in the inactivation process of class D β-lactamases. PMID:19919101

  17. Accumulation of Major Histocompatibility Complex Class II Molecules in Mast Cell Secretory Granules and Their Release upon Degranulation

    PubMed Central

    Raposo, Graça; Tenza, Danielle; Mecheri, Salahedine; Peronet, Roger; Bonnerot, Christian; Desaymard, Catherine

    1997-01-01

    To investigate the relationship between major histocompatibility complex (MHC) class II compartments, secretory granules, and secretory lysosomes, we analyzed the localization and fate of MHC class II molecules in mast cells. In bone marrow-derived mast cells, the bulk of MHC class II molecules is contained in two distinct compartments, with features of both lysosomal compartments and secretory granules defined by their protein content and their accessibility to endocytic tracers. Type I granules display internal membrane vesicles and are accessed by exogenous molecules after a time lag of 20 min; type II granules are reached by the endocytic tracer later and possess a serotonin-rich electron-dense core surrounded by a multivesicular domain. In these type I and type II granules, MHC class II molecules, mannose-6-phosphate receptors and lysosomal membrane proteins (lamp1 and lamp2) localize to small intralumenal vesicles. These 60–80-nm vesicles are released along with inflammatory mediators during mast cell degranulation triggered by IgE-antigen complexes. These observations emphasize the intimate connection between the endocytic and secretory pathways in cells of the hematopoietic lineage which allows regulated secretion of the contents of secretory lysosomes, including membrane proteins associated with small vesicles. PMID:9398681

  18. Accumulation of major histocompatibility complex class II molecules in mast cell secretory granules and their release upon degranulation.

    PubMed

    Raposo, G; Tenza, D; Mecheri, S; Peronet, R; Bonnerot, C; Desaymard, C

    1997-12-01

    To investigate the relationship between major histocompatibility complex (MHC) class II compartments, secretory granules, and secretory lysosomes, we analyzed the localization and fate of MHC class II molecules in mast cells. In bone marrow-derived mast cells, the bulk of MHC class II molecules is contained in two distinct compartments, with features of both lysosomal compartments and secretory granules defined by their protein content and their accessibility to endocytic tracers. Type I granules display internal membrane vesicles and are accessed by exogenous molecules after a time lag of 20 min; type II granules are reached by the endocytic tracer later and possess a serotonin-rich electron-dense core surrounded by a multivesicular domain. In these type I and type II granules, MHC class II molecules, mannose-6-phosphate receptors and lysosomal membrane proteins (lamp1 and lamp2) localize to small intralumenal vesicles. These 60-80-nm vesicles are released along with inflammatory mediators during mast cell degranulation triggered by IgE-antigen complexes. These observations emphasize the intimate connection between the endocytic and secretory pathways in cells of the hematopoietic lineage which allows regulated secretion of the contents of secretory lysosomes, including membrane proteins associated with small vesicles.

  19. Clinical, immunological and genetic features in eleven Algerian patients with major histocompatibility complex class II expression deficiency.

    PubMed

    Djidjik, Réda; Messaoudani, Nesrine; Tahiat, Azzedine; Meddour, Yanis; Chaib, Samia; Atek, Aziz; Khiari, Mohammed Elmokhtar; Benhalla, Nafissa Keltoum; Smati, Leila; Bensenouci, Abdelatif; Baghriche, Mourad; Ghaffor, Mohammed

    2012-08-03

    Presenting processed antigens to CD4+ lymphocytes during the immune response involves major histocompatibility complex class II molecules. MHC class II genes transcription is regulated by four transcription factors: CIITA, RFXANK, RFX5 and RFXAP. Defects in these factors result in major histocompatibility complex class II expression deficiency, a primary combined immunodeficiency frequent in North Africa. Autosomal recessive mutations in the RFXANK gene have been reported as being the principal defect found in North African patients with this disorder. In this paper, we describe clinical, immunological and genetic features of 11 unrelated Algerian patients whose monocytes display a total absence of MHC class II molecules. They shared mainly the same clinical picture which included protracted diarrhoea and respiratory tract recurrent infections. Genetic analysis revealed that 9 of the 11 patients had the same RFXANK founder mutation, a 26 bp deletion (named I5E6-25_I5E6+1, also known as 752delG26). Immunological and genetic findings in our series may facilitate genetic counselling implementation for Algerian consanguineous families. Further studies need to be conducted to determine 752delG26 heterozygous mutation frequency in Algerian population.

  20. Clinical, immunological and genetic features in eleven Algerian patients with major histocompatibility complex class II expression deficiency

    PubMed Central

    2012-01-01

    Presenting processed antigens to CD4+ lymphocytes during the immune response involves major histocompatibility complex class II molecules. MHC class II genes transcription is regulated by four transcription factors: CIITA, RFXANK, RFX5 and RFXAP. Defects in these factors result in major histocompatibility complex class II expression deficiency, a primary combined immunodeficiency frequent in North Africa. Autosomal recessive mutations in the RFXANK gene have been reported as being the principal defect found in North African patients with this disorder. In this paper, we describe clinical, immunological and genetic features of 11 unrelated Algerian patients whose monocytes display a total absence of MHC class II molecules. They shared mainly the same clinical picture which included protracted diarrhoea and respiratory tract recurrent infections. Genetic analysis revealed that 9 of the 11 patients had the same RFXANK founder mutation, a 26 bp deletion (named I5E6-25_I5E6+1, also known as 752delG26). Immunological and genetic findings in our series may facilitate genetic counselling implementation for Algerian consanguineous families. Further studies need to be conducted to determine 752delG26 heterozygous mutation frequency in Algerian population. PMID:22863278

  1. A Class of Practically Nowhere Differentiable Functions on the Complex Plane

    ERIC Educational Resources Information Center

    Hetzel, Andrew J.

    2006-01-01

    This note could find classroom use in an introductory course on complex analysis. Using some of the most significant theorems from complex analysis, the main result provides a simple method for transforming many elementary functions (defined on the complex plane) into everywhere continuous functions that are differentiable only on a nowhere dense…

  2. Synthesis of N-diisopropyl phosphoryl benzyltetrahydroisoquinoline, a new class of mitochondrial complexes I and III inhibitors.

    PubMed

    Andreu, I; Cabedo, N; Tormo, J R; Bermejo, A; Mello, R; Cortes, D

    2000-07-03

    The synthesis of N-(O,O-diisopropylphosphoryl)-benzyltetrahydroisoquinoline (3) has been achieved in a 'one pot' procedure from imine (2) and diisopropyl-phosphorochloridate (1) generated in situ (POCl3 + iPrOH). Compound 3 is the first benzyltetrahydroisoquinoline derivative found to be a potent inhibitor of mitochondrial complexes I and III, and therefore it opens a new perspective with this series of compounds as they can be considered as new class of antitumor agents.

  3. TCR-Like Biomolecules Target Peptide/MHC Class I Complexes on the Surface of Infected and Cancerous Cells

    PubMed Central

    Weidanz, Jon A.; Hawkins, Oriana; Verma, Bhavna; Hildebrand, William H.

    2012-01-01

    Summary The human leukocyte antigen (HLA; also called major histocompatibility, or MHC) class I system presents peptides that distinguish healthy from diseased cells. Therefore, the discovery of peptide/MHC class I markers can provide highly specific targets for immunotherapy. Over the course of almost two decades, various strategies have been used, with mixed success, to produce antibodies that have recognition specificity for unique peptide/MHC class I complexes that mark infected and cancerous cells. Using these antibody reagents, novel peptide/MHC class I targets have been directly validated on diseased cells and new insight has been gained into the mechanisms of antigen presentation. More recently, these antibodies have shown promise for clinical applications such as therapeutic targeting of cancerous and infected cells and diagnosis and imaging of diseased cells. In this review, we comprehensively describe the methods used to identify disease-specific peptide/MHC class I epitopes and generate antibodies to these markers. Finally, we offer several examples that illustrate the promise of using these antibodies as anti-cancer agents. PMID:22053972

  4. 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

  5. '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.

  6. Two putative subunits of a peptide pump encoded in the human major histocompatibility complex class II region.

    PubMed Central

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

    1991-01-01

    The class II 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 I 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 I molecules assemble. A second transporter gene, PSF2, was identified 10 kilobases (kb) from PSF1, near the class II 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 I molecules, although a distinct function of PSF2 cannot be ruled out. Images PMID:1946428

  7. Posttranscriptional inhibition of class I major histocompatibility complex presentation on hepatocytes and lymphoid cells in chronic woodchuck hepatitis virus infection.

    PubMed

    Michalak, T I; Hodgson, P D; Churchill, N D

    2000-05-01

    Woodchuck hepatitis virus (WHV), similar to human hepatitis B virus, causes acute liver inflammation that can progress to chronic hepatitis and hepatocellular carcinoma. WHV also invades cells of the host lymphatic system, where it persists for life. We report here that acute and chronic hepadnavirus hepatitis is characterized by a profound difference in the expression of class I major histocompatibility complex (MHC) molecules on the surface of infected hepatocytes and, notably, lymphoid cells. While acute WHV infection is accompanied by the enhanced hepatocyte surface presentation of class I MHC antigen and upregulated transcription of the relevant hepatic genes, inhibition of class I antigen display on liver cells is a uniform hallmark of chronic WHV infection. This inhibition in chronic hepatitis occurs despite augmented (as in acute infection) expression of hepatic genes for class I MHC heavy chain, beta(2)-microglobulin, and transporters associated with antigen processing (TAP1 and TAP2). Further, the class I antigen inhibition is not related to the histological severity of hepatocellular injury, the extent of lymphocytic infiltrations, the level of intrahepatic gamma interferon induction, or the hepatic WHV load. Importantly, the antigen expression is also inhibited on organ lymphoid cells of chronically infected hosts. The results obtained in this study demonstrate that the defective presentation of class I MHC molecules on cells supporting persistent WHV replication is due to viral posttranscriptional interference. This event may diminish the susceptibility of infected hepatocytes to virus-specific T-cell-mediated elimination, hinder virus clearance, and deregulate the class I MHC-dependent functions of the host immune system. This multifarious effect could be critical for perpetuation of liver damage and evasion of the antiviral immunological surveillance in chronic infection and therefore could be supportive of hepadnavirus persistence.

  8. 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.

  9. 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

  10. Human major histocompatibility complex class I gene that encodes a protein with a shortened cytoplasmic segment

    SciTech Connect

    Geraghty, D.E.; Koller, B.H.; Orr, H.T.

    1987-12-01

    The authors have cloned genomic DNA encoding a non-HLA-A, -B, -C class I gene located within a HindIII-generated restriction fragment of 6.0 kilobase pairs. This gene, designated HLA-6.0, is as homologous to HLA-A and HLA-B as they are to each other. The HLA class I protein encoded by HLA-6.0 is similar in organization to the HLA-A-, -B-, and -C-encoded proteins except that an in-frame termination codon prevents translation of a majority of the cytoplasmic region of the HLA-6.0 polypeptide. Moreover, the promoter region of HLA-6.0 resembles the promoter region of a Qa region gene. These structural features of HLA-6.0 suggest that this nonHLA-A, -B, -C gene is a structural homolog of a murine Qa region class I gene.

  11. Characterization of major histocompatibility complex class I, and class II DRB loci of captive and wild Indian leopards (Panthera pardus fusca).

    PubMed

    Parmar, Drashti R; Mitra, Siuli; Bhadouriya, Snehalata; Rao, Tirupathi; Kunteepuram, Vaishnavi; Gaur, Ajay

    2017-08-22

    The major histocompatibility complex (MHC), in vertebrate animals, is a multi-genic protein complex that encodes various receptors. During a disease, MHC interacts with the antigen and triggers a cascade of adaptive immune responses to overcome a disease outbreak. The MHC is very important region from immunological point of view, but it is poorly characterized among Indian leopards. During this investigation, we examined genetic diversity for MHC class I (MHC-I) and MHC class II-DRB (MHC-II) among wild and captive Indian leopards. This study estimated a pool of 9 and 17 alleles for MHC-I and MHC-II, respectively. The wild group of individuals showed higher nucleotide diversity and amino acid polymorphism compared to the captive group. A phylogenetic comparison with other felids revealed a clustering in MHC-I and interspersed presence in MHC-II sequences. A test for selection also revealed a deviation from neutrality at MHC-II DRB loci and higher non-synonymous substitution rate (dN) among the individuals from wild group. Further, the wild individuals showed higher dN for both MHC I and II genes compared to the group that was bred under captive conditions. These findings suggest the role of micro-evolutionary forces, such as pathogen-mediated selection, to cause MHC variations among the two groups of Indian leopards, because the two groups have been bred in two different environments for a substantial period of time. Since, MHC diversity is often linked with the quality of immunological health; the results obtained from this study fill the gap of knowledge on disease predisposition among wild and captive Indian leopards.

  12. Complexity of the Class B Phenotype in Autosomal Dominant Retinitis Pigmentosa Due to Rhodopsin Mutations

    PubMed Central

    Jacobson, Samuel G.; McGuigan, David B.; Sumaroka, Alexander; Roman, Alejandro J.; Gruzensky, Michaela L.; Sheplock, Rebecca; Palma, Judy; Schwartz, Sharon B.; Aleman, Tomas S.; Cideciyan, Artur V.

    2016-01-01

    Purpose Previously, patients with RHO mutations and a class A phenotype were found to have severe early-onset loss of rod function, whereas patients with a class B phenotype retained rod function at least in certain retinal regions. Here class B patients were studied at different disease stages to understand the topographic details of the phenotype in preparation for therapies of this regionalized retinopathy. Methods A cohort of patients with RHO mutations and class B phenotype (n = 28; ages 10–80 years) were studied with rod and cone perimetry and optical coherence tomography (OCT). Results At least three components of the phenotype were identified in these cross-sectional studies. Patients could have hemifield dysfunction, pericentral loss of function, or a diffuse rod sensitivity loss across the visual field. Combinations of these different patterns were also found. Colocalized photoreceptor layer thicknesses were in agreement with the psychophysical results. Conclusions These disorders with regional retinal variation of severity require pre-evaluations before enrollment into clinical trials to seek answers to questions about where in the retina would be appropriate to deliver focal treatments, and, for retina-wide treatment strategies, where in the retina should be monitored for therapeutic efficacy (or safety). PMID:27654411

  13. Three classes of inhibitors share a common binding domain in mitochondrial complex I (NADH:ubiquinone oxidoreductase).

    PubMed

    Okun, J G; Lümmen, P; Brandt, U

    1999-01-29

    We have developed two independent methods to measure equilibrium binding of inhibitors to membrane-bound and partially purified NADH:ubiquinone oxidoreductase (complex I) to characterize the binding sites for the great variety of hydrophobic compounds acting on this large and complicated enzyme. Taking advantage of a partial quench of fluorescence upon binding of the fenazaquin-type inhibitor 2-decyl-4-quinazolinyl amine to complex I in bovine submitochondrial particles, we determined a Kd of 17 +/- 3 nM and one binding site per complex I. Equilibrium binding studies with [3H]dihydrorotenone and the aminopyrimidine [3H]AE F119209 (4(cis-4-[3H]isopropyl cyclohexylamino)-5-chloro-6-ethyl pyrimidine) using partially purified complex I from Musca domestica exhibited little unspecific binding and allowed reliable determination of dissociation constants. Competition experiments consistently demonstrated that all tested hydrophobic inhibitors of complex I share a common binding domain with partially overlapping sites. Although the rotenone site overlaps with both the piericidin A and the capsaicin site, the latter two sites do not overlap. This is in contrast to the interpretation of enzyme kinetics that have previously been used to define three classes of complex I inhibitors. The existence of only one large inhibitor binding pocket in the hydrophobic part of complex I is discussed in the light of possible mechanisms of proton translocation.

  14. Engineering and characterization of a stabilized alpha1/alpha2 module of the class I major histocompatibility complex product Ld.

    PubMed

    Jones, Lindsay L; Brophy, Susan E; Bankovich, Alexander J; Colf, Leremy A; Hanick, Nicole A; Garcia, K Christopher; Kranz, David M

    2006-09-01

    The major histocompatibility complex (MHC) is the most polymorphic locus known, with thousands of allelic variants. There is considerable interest in understanding the diversity of structures and peptide-binding features represented by this class of proteins. Although many MHC proteins have been crystallized, others have not been amenable to structural or biochemical studies due to problems with expression or stability. In the present study, yeast display was used to engineer stabilizing mutations into the class I MHC molecule, Ld. The approach was based on previous studies that showed surface levels of yeast-displayed fusion proteins are directly correlated with protein stability. To engineer a more stable Ld, we selected Ld mutants with increased surface expression from randomly mutated yeast display libraries using anti-Ld antibodies or high affinity, soluble T-cell receptors (TCRs). The most stable Ld mutant, Ld-m31, consisted of a single-chain MHC module containing only the alpha1 and alpha2 domains. The enhanced stability was in part due to a single mutation (Trp-97 --> Arg), shown previously to be present in the allele Lq. Mutant Ld-m31 could bind to Ld peptides, and the specific peptide.Ld-m31 complex (QL9.Ld-m31) was recognized by alloreactive TCR 2C. A soluble form of the Ld-m31 protein was expressed in Escherichia coli and refolded from inclusion bodies at high yields. Surface plasmon resonance showed that TCRs bound to peptide.Ld-m31 complexes with affinities similar to those of native full-length Ld. The TCR and QL9.Ld-m31 formed complexes that could be resolved by native gel electrophoresis, suggesting that stabilized alpha1/alpha2 class I platforms may enable various structural studies.

  15. Participation of the interstitium in acute immune-complex nephritis: interstitial antigen accumulation, cellular infiltrate, and MHC class II expression

    PubMed Central

    PARRA, G; HERNÁNDEZ, S; MORENO, P; RODRÍGUEZ-ITURBE, B

    2003-01-01

    Bovine serum albumin (BSA) injected into the rabbits induces acute immune complex glomerulonephritis. Since albumin is filtered and reabsorbed in the tubules, we investigated whether tubulointerstitial cells participate in the pathogenesis of this experimental condition. For this purpose, we induced immune-complex nephritis in 45 rabbits with the injection of 125I-BSA and urinary BSA excretion, glomerular and tubulointerstitial BSA accumulation, lymphocyte infiltration, proliferative activity and MHC class II antigens were examined 2, 4–5 and 6–8 days after immunization. Proteinuria developed day 6–8. BSA was found in urine from day 2 (mean ± SE; 1089 ± 339 µg/24 h) and peaked on day 4 after immunization (2249 ± 1106). BSA content (cpm/g tissue) in tubulointerstitium (TI) and glomeruli were similar at day 2 (457 ± 45 and 407 ± 75, respectively), but afterward increased significantly in TI, reaching a peak level on day 5 (1026 ± 406) while remained unchanged in glomeruli (388 ± 95). At the same time, preceding the onset of proteinuria, maximal intensity of the lymphocyte infiltration, proliferative activity and MHC class II antigen expression in tubular cells, monocytes/macrophages and interstitial cells were observed. Our study shows that antigen is excreted in the urine and concentrated in TI in association with overexpression of MHC class II molecules and lymphocyte infiltration. These findings occur prior to the development of proteinuria and suggest that the tubulointerstitial cells play a critical role in the pathogenesis of this model. PMID:12823277

  16. Unusual association of beta 2-microglobulin with certain class I heavy chains of the murine major histocompatibility complex.

    PubMed Central

    Bushkin, Y; Tung, J S; Pinter, A; Michaelson, J; Boyse, E A

    1986-01-01

    Class I products of the major histocompatibility complex (MHC) comprise a heavy chain of about 45 kDa noncovalently linked to a 12-kDa beta 2-microglobulin (beta 2m) light chain encoded on a different chromosome. We find that class I products of some mouse strains include an additional 62-kDa molecule which on the following evidence consists of a heavy chain linked covalently with beta 2m. Production of the 62-kDa protein invariably accorded with the occurrence of cysteine at position 121 of the heavy chain (Kb,Kbm1,Kbm3,Dd, and Ld). Substitution of arginine at position 121 invariably accorded with absence of the 62-kDa protein (Kbm6,Kbm7,Kbm9,Kd, and Db). On the basis of observed production versus nonproduction of the 62-kDa molecule, predictions are made regarding residue 121 in class I products for which this is not yet known; namely, Kk, Ks, and Dk, which produce the 62-kDa molecule, as compared with Kj, Qa-2, and TL, which do not. Reported differences in immunologic reactivity between Kb mutant strains with Arg-121 in place of Cys-121 imply that the occurrence of 62-kDa class I products in mice of Cys-121 genotype has functional consequences. Images PMID:3510435

  17. Complex MHC class I gene transcription profiles and their functional impact in orangutans

    PubMed Central

    de Groot, Natasja G.; Heijmans, Corrine M.C.; van der Wiel, Marit K.H.; Blokhuis, Jeroen H.; Mulder, Arend; Guethlein, Lisbeth A.; Doxiadis, Gaby G.M.; Claas, Frans H.J.; Parham, Peter; Bontrop, Ronald E.

    2015-01-01

    MHC haplotypes of humans and the African great ape species have one copy of the MHC-A, -B, and -C genes. In contrast, MHC haplotypes of orangutans, the Asian great ape species, exhibit variation in the number of gene copies. An in-depth analysis of the MHC class I gene repertoire in the two orangutan species, Pongo abelii and Pongo pygmaeus, is presented here. This analysis involved Sanger and next-generation sequencing methodologies, revealing diverse and complicated transcription profiles for orangutan MHC-A, -B, and -C. Thirty-five previously unreported MHC class I alleles are described. The data demonstrate that each orangutan MHC haplotype has one copy of the MHC-A gene, and that the MHC-B region has been subject to duplication, giving rise to at least three MHC-B genes. The MHC-B*03 and -B*08 lineages of alleles each account for a separate MHC-B gene. All MHC-B*08 allotypes have the C1-epitope motif recognized by KIR. At least one other MHC-B gene is present, pointing to MHC-B alleles that are not B*03 or B*08. The MHC-C gene is present only on some haplotypes, and each MHC-C allotype has the C1-epitope. The transcription profiles demonstrate that MHC-A alleles are highly transcribed, whereas MHC-C alleles, when present, are transcribed at very low levels. The MHC-B alleles are transcribed to a variable extent and over a wide range. For those orangutan MHC class I allotypes that are detected by human monoclonal anti-HLA class I antibodies, the level of cell-surface expression of proteins correlates with the level of transcription of the allele. PMID:26685209

  18. Expression of rat class I major histocompatibility complex (MHC) alloantigens and hepatocytes and hepatoma cells

    SciTech Connect

    Hunt, J.M.; Desai, P.A.; Chakraborty, S.

    1986-03-05

    Altered expression of Class I MHC alloantigens has been reported for murine tumors, and may be associated with the tumorigenic phenotype of tumor cells. To characterize MHC Class I alloantigen expression on a chemically-induced transplantable rat hepatoma cell line, 17X, derived from a (WF x F344) F/sub 1/ rat, polyvalent anti-F344 and anti-WF rat alloantisera were first used to immunoprecipitate the rat RT1.A Class I MHC alloantigens expressed on primary (WF x F344) F/sub 1/ hepatocyptes in short-term monolayer cultures. Two-dimensional isoelectric focusing and SDS-PAGE of immunoprecipitates from /sup 35/S-methionine-labeled (WF x F344) F/sub 1/ hepatocytes clearly resolved the RT1.A/sup u/ (WF) and RT1.A/sup LvI/ (F344) parental alloantigens. Identical radiolabeling and immunoprecipitation failed to detect either parental alloantigen on the 17X hepatoma cells. However, indirect immunofluorescence and immunoblot analyses demonstrated the presence of parental alloantigens on the 17X cells. Immunization of F344 rats but not of WF rats with 17X cells resulted in antibodies cytotoxic for normal (WF X F344) F/sub 1/ spleen cells in the presence of complement. These findings indicate that a combination of detection techniques will be necessary to characterize altered alloantigen expression on rat hepatoma cells.

  19. 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

  20. Ruthenium complexes containing bis-benzimidazole derivatives as a new class of apoptosis inducers.

    PubMed

    Li, Linlin; Wong, Yum-Shing; Chen, Tianfeng; Fan, Cundong; Zheng, Wenjie

    2012-01-28

    A series of ruthenium complexes containing bis-benzimidazole derivatives have been synthesized and identified as able to target mitochondria and induce caspase-dependent apoptosis in cancer cells through superoxide overproduction.

  1. Identification and characterization of major histocompatibility complex class IIB alleles from three species of European ranid frogs

    PubMed Central

    A. Marosi, Béla; M. Kiemnec-Tyburczy, Karen; V. Ghira, Ioan; Sos, Tibor; Popescu, Octavian

    2014-01-01

    Immune genes of the major histocompatibility complex (MHC) are among the most polymorphic genes in the vertebrate genome. Due to their polymorphic nature, they are often used to assess the adaptive genetic variability of natural populations. This study describes the first molecular characterization of 13 partial MHC class IIB sequences from three European ranid frogs. The utility of previously published primers was expanded by using them to successfully amplify eight exon 2 alleles from Rana arvalis.We also designed a novel primer set that successfully amplified exon 2 from Pelophylax kurtmuelleri. Pelophylax lessonae was also designed as part of this study. Results indicate the presence of one or two class IIB loci in these three species. In R. arvalis, significant evidence of positive selection acting on MHC antigen binding sites was found. Many European ranid populations are experiencing disease-related declines; the newly developed primers can, therefore, be used for further population analyses of native frogs. PMID:27843985

  2. Transcription specificity of the class Ib genes SLA-6, SLA-7 and SLA-8 of the swine major histocompatibility complex and comparison with class Ia genes.

    PubMed

    Kusza, S; Flori, L; Gao, Y; Teillaud, A; Hu, R; Lemonnier, G; Bosze, Z; Bourneuf, E; Vincent-Naulleau, S; Rogel-Gaillard, C

    2011-10-01

    Our aim was to analyse the transcription levels of the three non-classical class Ib genes SLA-6, SLA-7 and SLA-8 of the swine major histocompatibility complex in various tissues and conditions and to compare them to the transcription levels of classical class Ia genes. Twenty-five adult tissues from two pig breeds, pig renal PK15 cells infected with the Pseudorabies virus, and peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide or a mixture of phorbol myristate acetate and ionomycin were included in our study. Relative transcription was quantified by quantitative real-time PCR. On average, in adult tissues and PBMCs and compared to SLA-6, the transcription level of SLA-Ia genes was 100-1000 times higher, the level of SLA-8 was 10-20 times higher, and that of SLA-7 was five times higher. Thus, SLA-8 is the most transcribed SLA-Ib gene, followed by the SLA-7 and SLA-6 genes. The highest transcription levels of SLA-Ib transcripts were found in the lymphoid organs, followed by the lung and the digestive tract. The tissue variability of expression levels was widest for the SLA-6 gene, with a 1:32 ratio between the lowest and highest levels in contrast to a 1:12 ratio for the SLA-7 and SLA-8 genes and a 1:16 ratio for the SLA-Ia genes. During PK-15 infection and PBMC stimulation, SLA-Ia and SLA-8 genes were downregulated, whereas SLA-6 and SLA-7 were upregulated, downregulated or not significantly modified. Our overall results confirm the tissue-wide transcription of the three SLA-Ib genes and suggest that they have complementary roles. © 2011 The Authors, Animal Genetics © 2011 Stichting International Foundation for Animal Genetics.

  3. Skeletal muscle major histocompatibility complex class I and II expression differences in adult and juvenile dermatomyositis

    PubMed Central

    Shinjo, Samuel Katsuyuki; Sallum, Adriana Maluf Elias; Silva, Clovis Artur; Marie, Suely Kazue Nagahashi

    2012-01-01

    OBJECTIVE: To analyze major histocompatibility complex expression in the muscle fibers of juvenile and adult dermatomyositis. METHOD: In total, 28 untreated adult dermatomyositis patients, 28 juvenile dermatomyositis patients (Bohan and Peter's criteria) and a control group consisting of four dystrophic and five Pompe's disease patients were analyzed. Routine histological and immunohistochemical (major histocompatibility complex I and II, StreptoABComplex/HRP, Dakopatts) analyses were performed on serial frozen muscle sections. Inflammatory cells, fiber damage, perifascicular atrophy and increased connective tissue were analyzed relative to the expression of major histocompatibility complexes I and II, which were assessed as negatively or positively stained fibers in 10 fields (200X). RESULTS: The mean ages at disease onset were 42.0±15.9 and 7.3±3.4 years in adult and juvenile dermatomyositis, respectively, and the symptom durations before muscle biopsy were similar in both groups. No significant differences were observed regarding gender, ethnicity and frequency of organ involvement, except for higher creatine kinase and lactate dehydrogenase levels in adult dermatomyositis (p<0.050). Moreover, a significantly higher frequency of major histocompatibility complex I (96.4% vs. 50.0%, p<0.001) compared with major histocompatibility complex II expression (14.3% vs. 53.6%, p = 0.004) was observed in juvenile dermatomyositis. Fiber damage (p = 0.006) and increased connective tissue (p<0.001) were significantly higher in adult dermatomyositis compared with the presence of perifascicular atrophy (p<0.001). The results of the histochemical and histological data did not correlate with the demographic data or with the clinical and laboratory features. CONCLUSION: The overexpression of major histocompatibility complex I was an important finding for the diagnosis of both groups, particularly for juvenile dermatomyositis, whereas there was lower levels of expression

  4. 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.

  5. The CLIP region of invariant chain plays a critical role in regulating major histocompatibility complex class II folding, transport, and peptide occupancy.

    PubMed

    Romagnoli, P; Germain, R N

    1994-09-01

    Invariant chain (Ii) contributes in a number of distinct ways to the proper functioning of major histocompatibility complex (MHC) class II molecules. These include promoting effective association and folding of newly synthesized MHC class II alpha and beta subunits, increasing transit of assembled heterodimers out of the endoplasmic reticulum (ER), inhibiting class II peptide binding, and facilitating class II movement to or accumulation in endosomes/lysosomes. Although the cytoplasmic tail of Ii makes a key contribution to the endocytic localization of class II, the relationship between the structure of Ii and its other diverse functions remains unknown. We show here that two thirds of the lumenal segment of Ii can be eliminated without affecting its contributions to the secretory pathway events of class II folding, ER to Golgi transport, or inhibition of peptide binding. These same experiments reveal that a short (25 residue) contiguous internal segment of Ii (the CLIP region), frequently found associated with purified MHC class II molecules, is critical for all three functions. Together with other recent findings, these results raise the possibility that the contributions of Ii to the early postsynthetic behavior of class II may depend on its interaction with the class II binding site. This would be consistent with the intracellular behavior of unoccupied MHC class I and class II molecules as incompletely folded proteins and imply a related structural basis for the similar contributions of Ii to class II and of short peptides to class I assembly and transport.

  6. 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

  7. Optimization of DNA delivery by three classes of hybrid nanoparticle/DNA complexes

    PubMed Central

    2010-01-01

    Plasmid DNA encoding a luciferase reporter gene was complexed with each of six different hybrid nanoparticles (NPs) synthesized from mixtures of poly (D, L-lactide-co-glycolide acid) (PLGA 50:50) and the cationic lipids DOTAP (1, 2-Dioleoyl-3-Trimethyammonium-Propane) or DC-Chol {3β-[N-(N', N'-Dimethylaminoethane)-carbamyl] Cholesterol}. Particles were 100-400 nm in diameter and the resulting complexes had DNA adsorbed on the surface (out), encapsulated (in), or DNA adsorbed and encapsulated (both). A luciferase reporter assay was used to quantify DNA expression in 293 cells for the uptake of six different NP/DNA complexes. Optimal DNA delivery occurred for 105 cells over a range of 500 ng - 10 μg of NPs containing 20-30 μg DNA per 1 mg of NPs. Uptake of DNA from NP/DNA complexes was found to be 500-600 times as efficient as unbound DNA. Regression analysis was performed and lines were drawn for DNA uptake over a four week interval. NP/DNA complexes with adsorbed NPs (out) showed a large initial uptake followed by a steep slope of DNA decline and large angle of declination; lines from uptake of adsorbed and encapsulated NPs (both) also exhibited a large initial uptake but was followed by a gradual slope of DNA decline and small angle of declination, indicating longer times of luciferase expression in 293 cells. NPs with encapsulated DNA only (in), gave an intermediate activity. The latter two effects were best seen with DOTAP-NPs while the former was best seen with DC-Chol-NPs. These results provide optimal conditions for using different hybrid NP/DNA complexes in vitro and in the future, will be tested in vivo. PMID:20181278

  8. 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.

  9. 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. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Certain class of higher-dimensional simplicial complexes and universal C (∗)-algebras.

    PubMed

    Omran, Saleh

    2014-01-01

    In this article we introduce a universal C (∗)-algebras associated to certain simplicial flag complexes. We denote it by [Formula: see text]it is a subalgebra of the noncommutative n-sphere which introduced by J.Cuntz. We present a technical lemma to determine the quotient of the skeleton filtration of a general universal C (∗)-algebra associated to a simplicial flag complex. We examine the K-theory of this algebra. Moreover we prove that any such algebra divided by the ideal I 2 is commutative. 19 K 46.

  11. Failure of a protective major histocompatibility complex class II molecule to delete autoreactive T cells in autoimmune diabetes.

    PubMed

    Slattery, R M; Miller, J F; Heath, W R; Charlton, B

    1993-11-15

    The association of major histocompatibility complex genes with autoimmune diseases is firmly established, but the mechanisms by which these genes confer resistance or susceptibility remain controversial. The controversy extends to the nonobese diabetic (NOD) mouse that develops disease similar to human insulin-dependent diabetes mellitus. The transgenic incorporation of certain class II major histocompatibility complex genes protects NOD mice from diabetes, and clonal deletion or functional silencing of autoreactive T cells has been proposed as the mechanism by which these molecules provide protection. We show that neither thymic deletion nor anergy of autoreactive T cells occurs in NOD mice transgenic for I-Ak. Autoreactive T cells are present, functional, and can transfer diabetes to appropriate NOD-recipient mice.

  12. Oracle separation of complexity classes and lower bounds for perceptrons solving separation problems

    NASA Astrophysics Data System (ADS)

    Vereshchagin, N. K.

    1995-12-01

    In the first part of the paper we prove that, relative to a random oracle, the class NP contains infinite sets having no infinite Co-NP-subsets (Co-NP-immune sets). In the second part we prove that perceptrons separating Boolean matrices in which each row contains at least one 1 from matrices in which many rows (say 99% of them) have no 1's must have either large size or large order. This result partially strengthens the "one-in-a-box"' theorem of Minsky and Papert [16] which states that perceptrons of small order cannot decide if every row of a given Boolean matrix has a 1. As a corollary, we prove that AM {}\\cap{}Co-AM {}\

  13. Capital dissipation minimization for a class of complex irreversible resource exchange processes

    NASA Astrophysics Data System (ADS)

    Xia, Shaojun; Chen, Lingen

    2017-05-01

    A model of a class of irreversible resource exchange processes (REPes) between a firm and a producer with commodity flow leakage from the producer to a competitive market is established in this paper. The REPes are assumed to obey the linear commodity transfer law (LCTL). Optimal price paths for capital dissipation minimization (CDM) (it can measure economic process irreversibility) are obtained. The averaged optimal control theory is used. The optimal REP strategy is also compared with other strategies, such as constant-firm-price operation and constant-commodity-flow operation, and effects of the amount of commodity transferred and the commodity flow leakage on the optimal REP strategy are also analyzed. The commodity prices of both the producer and the firm for the CDM of the REPes with commodity flow leakage change with the time exponentially.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  15. Major histocompatibility complex class I molecules bind natural peptide ligands lacking the amino-terminal binding residue in vivo.

    PubMed

    Yague, J; Marina, A; Vazquez, J; Lopez De Castro, J A

    2001-11-23

    Major histocompatibility complex (MHC) class I-peptide complexes are stabilized by multiple interactions, including those of the peptidic NH(2)-terminal group in the A pocket of the MHC molecule. In this study, the characterization of four natural HLA-B39 ligands lacking the amino-terminal binding residue is reported. These peptides were found in the endogenous peptide pool of one or more of the B*3901, B*3905, and B*3909 allotypes and sequenced by nanoelectrospray mass spectrometry. Control experiments ruled out that they resulted from exopeptidase trimming of their NH(2)-terminally extended counterparts: NAc-SHVAVENAL, EHGPNPIL, IHEPEPHIL, and EHAGVISVL, also present in the same peptide pools, during purification. HAGVISVL and HVAVENAL behaved similarly to the corresponding NH(2)-terminally extended peptides in their binding to B*3901 and B*3909 at the cell surface in vitro, and in cell surface stabilization of B*3901. This is, to our knowledge, the first demonstration that peptides lacking the amino-terminal binding residue bind in vivo to classical MHC class I molecules. The results indicate that canonical MHC-peptide interactions in the A pocket are not always necessary for endogenous peptide presentation.

  16. The novel endosomal membrane protein Ema interacts with the class C Vps-HOPS complex to promote endosomal maturation.

    PubMed

    Kim, Sungsu; Wairkar, Yogesh P; Daniels, Richard W; DiAntonio, Aaron

    2010-03-08

    Endosomal maturation is critical for accurate and efficient cargo transport through endosomal compartments. Here we identify a mutation of the novel Drosophila gene, ema (endosomal maturation defective) in a screen for abnormal synaptic overgrowth and defective protein trafficking. Ema is an endosomal membrane protein required for trafficking of fluid-phase and receptor-mediated endocytic cargos. In the ema mutant, enlarged endosomal compartments accumulate as endosomal maturation fails, with early and late endosomes unable to progress into mature degradative late endosomes and lysosomes. Defective endosomal down-regulation of BMP signaling is responsible for the abnormal synaptic overgrowth. Ema binds to and genetically interacts with Vps16A, a component of the class C Vps-HOPS complex that promotes endosomal maturation. The human orthologue of ema, Clec16A, is a candidate susceptibility locus for autoimmune disorders, and its expression rescues the Drosophila mutant demonstrating conserved function. Characterizing this novel gene family identifies a new component of the endosomal pathway and provides insights into class C Vps-HOPS complex function.

  17. 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.

  18. 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.

  19. Altered Expression of TAP-1 and Major Histocompatibility Complex Class I in Laryngeal Papillomatosis: Correlation of TAP-1 with Disease

    PubMed Central

    Vambutas, Andrea; Bonagura, Vincent R.; Steinberg, Bettie M.

    2000-01-01

    Recurrent respiratory papillomatosis (RRP) is an insidious disease caused by human papillomavirus (HPV) infection. It is characterized by a variable clinical course that can include frequent disease recurrence, significant morbidity, and occasional mortality. The mechanisms responsible for the variability in the clinical course and the persistence of latent HPV infection remain unknown. Effective T-cell-mediated clearance of HPV-infected cells may be defective in patients with RRP, leading to recurrent disease and failure to suppress latent HPV reactivation. This study describes the down-regulation of the transporter associated with antigen presentation (TAP-1) and the major histocompatibility complex (MHC) class I protein expression in laryngeal papilloma tissue biopsies and cell culture of primary explants. There was a statistically significant correlation between reduction of TAP-1 expression in biopsy tissues and rapid recurrence of disease. Patients with RRP had less frequent recurrence if their papillomas expressed TAP-1 at levels close to that of normal tissue, compared with those with very low expression of TAP-1, who had frequent recurrence (32 versus 5 weeks to the next surgical intervention). These findings suggest that HPV may evade immune recognition by down-regulating class I MHC cell surface expression via decreased TAP-1 levels. Expression of TAP-1 could be used for prognostic evaluation of disease severity. Gamma interferon was able to restore class I MHC expression at the surfaces of laryngeal papilloma cells in culture. This up-regulation of class I MHC antigen at the cell surface potentially allows the infected cell to become a target for the immune system again. This finding provides some promise for nonsurgical treatment of laryngeal papillomas. PMID:10618282

  20. 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

  1. A complex family of class-II restriction endonucleases, DsaI-VI, in Dactylococcopsis salina.

    PubMed

    Laue, F; Evans, L R; Jarsch, M; Brown, N L; Kessler, C

    1991-01-02

    A series of class-II restriction endonucleases (ENases) was discovered in the halophilic, phototrophic, gas-vacuolated cyanobacterium Dactylococcopsis salina sp. nov. The six novel enzymes are characterized by the following recognition sequences and cut positions: 5'-C decreases CRYGG-3' (DsaI); 5'-GG decreases CC-3' (DsaII); 5'-R decreases GATCY-3' (DsaIII); 5'-G decreases GWCC-3' (DsaIV); 5'-decreases CCNGG-3' (DsaV); and 5'-GTMKAC-3' (DsaVI), where W = A or T, M = A or C, K = G or T, and N = A, G, C or T. In addition, traces of further possible activity were detected. DsaI has a novel sequence specificity and DsaV is an isoschizomer of ScrFI, but with a novel cut specificity. A purification procedure was established to separate all six ENases, resulting in their isolation free of contaminating nuclease activities. DsaI cleavage is influenced by N6-methyladenine residues [derived from the Escherichia coli-encoded DNA methyltransferase (MTase) M.Eco damI] within the overlapping sequence, 5'-CCRYMGGATC-3'; DsaV hydrolysis is inhibited by a C-5-methylcytosine residue in its recognition sequence (5'-CMCNGG-3'), generated in some DsaV sites by the E. coli-encoded MTase, M.Eco dcmI.

  2. Effects of pH and polysaccharides on peptide binding to class II major histocompatibility complex molecules.

    PubMed Central

    Harding, C V; Roof, R W; Allen, P M; Unanue, E R

    1991-01-01

    The binding of immunogenic peptides to class II major histocompatibility molecules was examined at various pH values. We studied binding of peptides containing residues 52-61 from hen egg lysozyme (HEL) to I-Ak on fixed peritoneal macrophages or to solubilized affinity-purified I-Ak. Optimum binding occurred at pH 5.5-6.0 with accelerated kinetics relative to pH 7.4; equilibrium binding was also higher at pH 5.5-6.0 than at 7.4. Similar enhancement at pH 5-6 was observed for the binding of hemoglobin-(64-76) to I-Ek and of ribonuclease-(41-61) to I-Ak. In contrast, the binding of HEL-(34-45) to I-Ak was minimally enhanced at acid pH. Dissociation of cell-associated or purified peptide-I-Ak complexes was minimal between pH 5.5 and 7.4, with increased dissociation only at or below pH 4.0 [HEL-(46-61)] or pH 5.0 [HEL-(34-45)]. Thus, optimum peptide binding occurs at pH values similar to the endosomal environment, where the complexes appear to be formed during antigen processing. In addition, we examined the effect of a number of polysaccharides on the binding of peptide to I-Ak. None of these competed with the HEL peptide 125I-labeled YE52-61 for binding to I-Ak. [3H]Dextran also failed to bind purified I-Ak. Polysaccharides do not appear to bind to class II major histocompatibility complex molecules, which explains the T-cell independence of polysaccharide antigens. PMID:2011583

  3. Giant panda BAC library construction and assembly of a 650-kb contig spanning major histocompatibility complex class II region

    PubMed Central

    Zeng, Chang-Jun; Pan, Hui-Juan; Gong, Shao-Bin; Yu, Jian-Qiu; Wan, Qiu-Hong; Fang, Sheng-Guo

    2007-01-01

    Background Giant panda is rare and endangered species endemic to China. The low rates of reproductive success and infectious disease resistance have severely hampered the development of captive and wild populations of the giant panda. The major histocompatibility complex (MHC) plays important roles in immune response and reproductive system such as mate choice and mother-fetus bio-compatibility. It is thus essential to understand genetic details of the giant panda MHC. Construction of a bacterial artificial chromosome (BAC) library will provide a new tool for panda genome physical mapping and thus facilitate understanding of panda MHC genes. Results A giant panda BAC library consisting of 205,800 clones has been constructed. The average insert size was calculated to be 97 kb based on the examination of 174 randomly selected clones, indicating that the giant panda library contained 6.8-fold genome equivalents. Screening of the library with 16 giant panda PCR primer pairs revealed 6.4 positive clones per locus, in good agreement with an expected 6.8-fold genomic coverage of the library. Based on this BAC library, we constructed a contig map of the giant panda MHC class II region from BTNL2 to DAXX spanning about 650 kb by a three-step method: (1) PCR-based screening of the BAC library with primers from homologous MHC class II gene loci, end sequences and BAC clone shotgun sequences, (2) DNA sequencing validation of positive clones, and (3) restriction digest fingerprinting verification of inter-clone overlapping. Conclusion The identifications of genes and genomic regions of interest are greatly favored by the availability of this giant panda BAC library. The giant panda BAC library thus provides a useful platform for physical mapping, genome sequencing or complex analysis of targeted genomic regions. The 650 kb sequence-ready BAC contig map of the giant panda MHC class II region from BTNL2 to DAXX, verified by the three-step method, offers a powerful tool for

  4. Measles virus transmembrane fusion protein synthesized de novo or presented in immunostimulating complexes is endogenously processed for HLA class I- and class II-restricted cytotoxic T cell recognition

    PubMed Central

    1992-01-01

    The routes used by antigen-presenting cells (APC) to convert the transmembrane fusion glycoprotein (F) of measles virus (MV) to HLA class I and class II presentable peptides have been examined, using cloned cytotoxic T lymphocytes in functional assays. Presentation by Epstein-Barr virus-transformed B lymphoblastoid cell lines was achieved using live virus, ultraviolet light-inactivated virus, and purified MV- F delivered either as such or incorporated in immunostimulating complexes (MV-F-ISCOM). Only live virus and MV-F-ISCOM allow presentation by class I molecules, while all antigen preparations permit class II-restricted presentation. We observe presentation of MV- F from live virus and as MV-F-ISCOM by class II molecules in a fashion that is not perturbed by chloroquine. Our studies visualize novel presentation pathways of type I transmembrane proteins. PMID:1613454

  5. MHC class II complexes sample intermediate states along the peptide exchange pathway

    PubMed Central

    Wieczorek, Marek; Sticht, Jana; Stolzenberg, Sebastian; Günther, Sebastian; Wehmeyer, Christoph; El Habre, Zeina; Álvaro-Benito, Miguel; Noé, Frank; Freund, Christian

    2016-01-01

    The presentation of peptide-MHCII complexes (pMHCIIs) for surveillance by T cells is a well-known immunological concept in vertebrates, yet the conformational dynamics of antigen exchange remain elusive. By combining NMR-detected H/D exchange with Markov modelling analysis of an aggregate of 275 microseconds molecular dynamics simulations, we reveal that a stable pMHCII spontaneously samples intermediate conformations relevant for peptide exchange. More specifically, we observe two major peptide exchange pathways: the kinetic stability of a pMHCII's ground state defines its propensity for intrinsic peptide exchange, while the population of a rare, intermediate conformation correlates with the propensity of the HLA-DM-catalysed pathway. Helix-destabilizing mutants designed based on our model shift the exchange behaviour towards the HLA-DM-catalysed pathway and further allow us to conceptualize how allelic variation can shape an individual's MHC restricted immune response. PMID:27827392

  6. Gold-heterometal complexes. Evolution of a new class of luminescent materials.

    PubMed

    Fernández, Eduardo J; Laguna, Antonio; López-de-Luzuriaga, José M

    2007-05-28

    A very promising area of research in which metallophilic attraction has become the dominating factor determining the structural patterns that give rise to luminescent materials is discussed. In addition to the intrinsic conditions that a gold complex requires to show luminescence, we show how the type and number of the ligands, the coordination environments around the metal centres, the temperature, the heterometal, the metal-metal distances, etc., increase the possibilities of electronic transitions and, hence, multiply the factors that affect the energy and number of emissions. We think that far from being a hindrance or a problem these findings actually give rise to a fascinating area of research with promising future applications, for instance, in imaging technology, vapour sensors, light emitting devices or even medicine, where the demand for optoelectronic devices is increasing every day.

  7. Circulating and tissue-bound immune complexes in allergic vasculitis: relationship between immunoglobulin class and clinical features.

    PubMed Central

    Kauffmann, R H; Herrmann, W A; Meijer, C J; Daha, M R; Vanes, L A

    1980-01-01

    Sixty-two patients with allergic vasculitis and histological evidence of leukocytoclastic vasculitis were examined to determine whether clinical features, such as course and degree of systemic involvement, could be related to the class of the immunoglobulins in immune complexes (IC) in both the circulation and the vessel wall. Circulating IC were detected with the 125I-C1q-binding assay (C1q-BA), an anti-IgA inhibition binding assay (a-IgA-Inh BA) and the conglutinin-binding assay (Con-BA). Stabilized heat-aggregated IgG, IgA and IgM were used to determine the immunoglobulin class specificity of these assays. With the C1q-BA only aggregated IgG were detected, with the a-IgA-Inh Ba only aggregates containing IgA. With the Con-BA IgG, IgA or IgM in reactive aggregates were identified with class-specific antibodies. For patients with acute cutaneous vasculitis all assays were negative. The a-IgA-Inh BA was frequently positive in sera of patients with chronic cutaneous and acute systemic vasculitis; in the latter group conglutinin-binding IC of the IgG, IgA and IgM class were also detected. Levels in the C1q-BA were high for patients with chronic systemic vasculitis. Comparison of the results of the IC assays with the immunofluorescence studies of the cutaneous vessel walls of the same patients showed agreement between the results of the C1q-BA and deposition of IgG and the results of the a-IgA-Inh BA and IgA deposition. The class of immunoglobulin in conglutinin-binding IC did not correspond as well with the immunoglobulins in vessel walls. This study shows that certain clinical features of allergic vasculitis are related to the composition of the IC in the circulation and in the vessel wall. PMID:7438561

  8. Automatic sequence design of major histocompatibility complex class I binding peptides impairing CD8+ T cell recognition.

    PubMed

    Ogata, Koji; Jaramillo, Alfonso; Cohen, William; Briand, Jean-Paul; Connan, Francine; Choppin, Jeannine; Muller, Sylviane; Wodak, Shoshana J

    2003-01-10

    An automatic protein design procedure was used to compute amino acid sequences of peptides likely to bind the HLA-A2 major histocompatibility complex (MHC) class I allele. The only information used by the procedure are a structural template, a rotamer library, and a well established classical empirical force field. The calculations are performed on six different templates from x-ray structures of HLA-A0201-peptide complexes. Each template consists of the bound peptide backbone and the full atomic coordinates of the MHC protein. Sequences within 2 kcal/mol of the minimum energy sequence are computed for each template, and the sequences from all the templates are combined and ranked by their energies. The five lowest energy peptide sequences and five other low energy sequences re-ranked on the basis of their similarity to peptides known to bind the same MHC allele are chemically synthesized and tested for their ability to bind and form stable complexes with the HLA-A2 molecule. The most efficient binders are also tested for inhibition of the T cell receptor recognition of two known CD8(+) T effectors. Results show that all 10 peptides bind the expected MHC protein. The six strongest binders also form stable HLA-A2-peptide complexes, albeit to varying degrees, and three peptides display significant inhibition of CD8(+) T cell recognition. These results are rationalized in light of our knowledge of the three-dimensional structures of the HLA-A2-peptide and HLA-A2-peptide-T cell receptor complexes.

  9. Rhenium Complexes Based on 2-Pyridyl-1,2,3-triazole Ligands: A New Class of CO2 Reduction Catalysts.

    PubMed

    Ching, H Y Vincent; Wang, Xia; He, Menglan; Perujo Holland, Noemi; Guillot, Régis; Slim, Cyrine; Griveau, Sophie; Bertrand, Hélène C; Policar, Clotilde; Bedioui, Fethi; Fontecave, Marc

    2017-03-06

    A series of [Re(N^N)(CO)3(X)] (N^N = diimine and X = halide) complexes based on 4-(2-pyridyl)-1,2,3-triazole (pyta) and 1-(2-pyridyl)-1,2,3-triazole (tapy) diimine ligands have been prepared and electrochemically characterized. The first ligand-based reduction process is shown to be highly sensitive to the nature of the isomer as well as to the substituents on the pyridyl ring, with the peak potential changing by up to 700 mV. The abilities of this class of complexes to catalyze the electroreduction and photoreduction of CO2 were assessed for the first time. It is found that only Re pyta complexes that have a first reduction wave with a peak potential at ca. -1.7 V vs SCE are active, producing CO as the major product, together with small amounts of H2 and formic acid. The catalytic wave that is observed in the CVs is enhanced by the addition of water or trifluoroethanol as a proton source. Long-term controlled potential electrolysis experiments gave total Faradaic yield close to 100%. In particular, functionalization of the triazolyl ring with a 2,4,6-tri-tert-butylphenyl group provided the catalyst with a remarkable stability.

  10. 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

  11. Message survival and decision dynamics in a class of reactive complex systems subject to external fields

    NASA Astrophysics Data System (ADS)

    Rodriguez Lucatero, C.; Schaum, A.; Alarcon Ramos, L.; Bernal-Jaquez, R.

    2014-07-01

    In this study, the dynamics of decisions in complex networks subject to external fields are studied within a Markov process framework using nonlinear dynamical systems theory. A mathematical discrete-time model is derived using a set of basic assumptions regarding the convincement mechanisms associated with two competing opinions. The model is analyzed with respect to the multiplicity of critical points and the stability of extinction states. Sufficient conditions for extinction are derived in terms of the convincement probabilities and the maximum eigenvalues of the associated connectivity matrices. The influences of exogenous (e.g., mass media-based) effects on decision behavior are analyzed qualitatively. The current analysis predicts: (i) the presence of fixed-point multiplicity (with a maximum number of four different fixed points), multi-stability, and sensitivity with respect to the process parameters; and (ii) the bounded but significant impact of exogenous perturbations on the decision behavior. These predictions were verified using a set of numerical simulations based on a scale-free network topology.

  12. SCIMP, a transmembrane adaptor protein involved in major histocompatibility complex class II signaling.

    PubMed

    Draber, Peter; Vonkova, Ivana; Stepanek, Ondrej; Hrdinka, Matous; Kucova, Marketa; Skopcova, Tereza; Otahal, Pavel; Angelisova, Pavla; Horejsi, Vaclav; Yeung, Mandy; Weiss, Arthur; Brdicka, Tomas

    2011-11-01

    Formation of the immunological synapse between an antigen-presenting cell (APC) and a T cell leads to signal generation in both cells involved. In T cells, the lipid raft-associated transmembrane adaptor protein LAT plays a central role. Its phosphorylation is a crucial step in signal propagation, including the calcium response and mitogen-activated protein kinase activation, and largely depends on its association with the SLP76 adaptor protein. Here we report the discovery of a new palmitoylated transmembrane adaptor protein, termed SCIMP. SCIMP is expressed in B cells and other professional APCs and is localized in the immunological synapse due to its association with tetraspanin-enriched microdomains. In B cells, it is constitutively associated with Lyn kinase and becomes tyrosine phosphorylated after major histocompatibility complex type II (MHC-II) stimulation. When phosphorylated, SCIMP binds to the SLP65 adaptor protein and also to the inhibitory kinase Csk. While the association with SLP65 initiates the downstream signaling cascades, Csk binding functions as a negative regulatory loop. The results suggest that SCIMP is involved in signal transduction after MHC-II stimulation and therefore serves as a regulator of antigen presentation and other APC functions.

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

    PubMed

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

    2010-12-01

    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 β1 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 IIβ exon 2. Two distinct intron sequences were recovered, suggesting the presence of at least two class IIβ 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 β1 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.

  14. 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.

  15. Two distinct nuclear factors bind the conserved regulatory sequences of a rabbit major histocompatibility complex class II gene.

    PubMed Central

    Sittisombut, N

    1988-01-01

    The constitutive coexpression of the major histocompatibility complex (MHC) class II genes in B lymphocytes requires positive, trans-acting transcriptional factors. The need for these trans-acting factors has been suggested by the reversion of the MHC class II-negative phenotype of rare B-lymphocyte mutants through somatic cell fusion with B cells or T-cell lines. The mechanism by which the trans-acting factors exert their effect on gene transcription is unknown. The possibility that two highly conserved DNA sequences, located 90 to 100 base pairs (bp) (the A sequence) and 60 to 70 bp (the B sequence) upstream of the transcription start site of the class II genes, are recognized by the trans-acting factors was investigated in this study. By using the gel electrophoresis retardation assay, a minimum of two proteins which specifically bound the conserved A or B sequence of a rabbit DP beta gene were identified in murine nuclear extracts of a B-lymphoma cell line, A20-2J. Fractionation of nuclear extract through a heparin-agarose column allowed the identification of one protein, designated NF-MHCIIB, which bound an oligonucleotide containing the B sequence and protected the entire B sequence in the DNase I protection analysis. Another protein, designated NF-MHCIIA, which bound an oligonucleotide containing the A sequence and partially protected the 3' half of this sequence, was also identified. NF-MHCIIB did not protect a CCAAT sequence located 17 bp downstream of the B sequence. The possible relationship between these DNA-binding factors and the trans-acting factors identified in the cell fusion experiments is discussed. Images PMID:3133552

  16. The proteolytic fragments generated by vertebrate proteasomes: structural relationships to major histocompatibility complex class I binding peptides.

    PubMed Central

    Niedermann, G; King, G; Butz, S; Birsner, U; Grimm, R; Shabanowitz, J; Hunt, D F; Eichmann, K

    1996-01-01

    Proteasomes are involved in the proteolytic generation of major histocompatibility complex (MHC) class I epitopes but their exact role has not been elucidated. We used highly purified murine 20S proteasomes for digestion of synthetic 22-mer and 41/44-mer ovalbumin partial sequences encompassing either an immunodominant or a marginally immunogenic epitope. At various times, digests were analyzed by pool sequencing and by semiquantitative electrospray ionization mass spectrometry. Most dual cleavage fragments derived from 22-mer peptides were 7-10 amino acids long, with octa- and nonamers predominating. Digestion of 41/44-mer peptides initially revealed major cleavage sites spaced by two size ranges, 8 or 9 amino acids and 14 or 15 amino acids, followed by further degradation of the latter as well as of larger single cleavage fragments. The final size distribution was slightly broader than that of fragments derived from 22-mer peptides. The majority of peptide bonds were cleaved, albeit with vastly different efficiencies. This resulted in multiple overlapping proteolytic fragments including a limited number of abundant peptides. The immunodominant epitope was generated abundantly whereas only small amounts of the marginally immunogenic epitope were detected. The frequency distributions of amino acids flanking proteasomal cleavage sites are correlated to that reported for corresponding positions of MHC class I binding peptides. The results suggest that proteasomal degradation products may include fragments with structural properties similar to MHC class I binding peptides. Proteasomes may thus be involved in the final stages of proteolytic epitope generation, often without the need for downstream proteolytic events. Images Fig. 1 PMID:8710912

  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 Central

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

    1987-01-01

    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. Images Fig. 1 Fig. 2 Fig. 3 PMID:3115648

  18. Robust H ∞ Filtering for a Class of Complex Networks with Stochastic Packet Dropouts and Time Delays

    PubMed Central

    Lyu, Ming; Guo, Pengfei; Bo, Yuming

    2014-01-01

    The robust H ∞ filtering problem is investigated for a class of complex network systems which has stochastic packet dropouts and time delays, combined with disturbance inputs. The packet dropout phenomenon occurs in a random way and the occurrence probability for each measurement output node is governed by an individual random variable. Besides, the time delay phenomenon is assumed to occur in a nonlinear vector-valued function. We aim to design a filter such that the estimation error converges to zero exponentially in the mean square, while the disturbance rejection attenuation is constrained to a given level by means of the H ∞ performance index. By constructing the proper Lyapunov-Krasovskii functional, we acquire sufficient conditions to guarantee the stability of the state detection observer for the discrete systems, and the observer gain is also derived by solving linear matrix inequalities. Finally, an illustrative example is provided to show the usefulness and effectiveness of the proposed design method. PMID:24987738

  19. Antigen Presentation by Dendritic Cells after Immunization with DNA Encoding a Major Histocompatibility Complex Class II–restricted Viral Epitope

    PubMed Central

    Casares, Sofia; Inaba, Kayo; Brumeanu, Teodor-Doru; Steinman, Ralph M.; Bona, Constantin A.

    1997-01-01

    Intramuscular and intracutaneous immunization with naked DNA can vaccinate animals to the encoded proteins, but the underlying mechanisms of antigen presentation are unclear. We used DNA that encodes an A/PR/8/34 influenza peptide for CD4 T cells and that elicits protective antiviral immunity. DNA-transfected, cultured muscle cells released the influenza polypeptide, which then could be presented on the major histocompatibility complex class II molecules of dendritic cells. When DNA was injected into muscles or skin, and antigen-presenting cells were isolated from either the draining lymph nodes or the skin, dendritic, but not B, cells presented antigen to T cells and carried plasmid DNA. We suggest that the uptake of DNA and/or the protein expressed by dendritic cells triggers immune responses to DNA vaccines. PMID:9348305

  20. Event-based state estimation for a class of complex networks with time-varying delays: A comparison principle approach

    NASA Astrophysics Data System (ADS)

    Zhang, Wenbing; Wang, Zidong; Liu, Yurong; Ding, Derui; Alsaadi, Fuad E.

    2017-01-01

    The paper is concerned with the state estimation problem for a class of time-delayed complex networks with event-triggering communication protocol. A novel event generator function, which is dependent not only on the measurement output but also on a predefined positive constant, is proposed with hope to reduce the communication burden. A new concept of exponentially ultimate boundedness is provided to quantify the estimation performance. By means of the comparison principle, some sufficient conditions are obtained to guarantee that the estimation error is exponentially ultimately bounded, and then the estimator gains are obtained in terms of the solution of certain matrix inequalities. Furthermore, a rigorous proof is proposed to show that the designed triggering condition is free of the Zeno behavior. Finally, a numerical example is given to illustrate the effectiveness of the proposed event-based estimator.

  1. Recent advances in Major Histocompatibility Complex (MHC) class I antigen presentation: Plastic MHC molecules and TAPBPR-mediated quality control

    PubMed Central

    van Hateren, Andy; Bailey, Alistair; Elliott, Tim

    2017-01-01

    We have known since the late 1980s that the function of classical major histocompatibility complex (MHC) class I molecules is to bind peptides and display them at the cell surface to cytotoxic T cells. Recognition by these sentinels of the immune system can lead to the destruction of the presenting cell, thus protecting the host from pathogens and cancer. Classical MHC class I molecules (MHC I hereafter) are co-dominantly expressed, polygenic, and exceptionally polymorphic and have significant sequence diversity. Thus, in most species, there are many different MHC I allotypes expressed, each with different peptide-binding specificity, which can have a dramatic effect on disease outcome. Although MHC allotypes vary in their primary sequence, they share common tertiary and quaternary structures. Here, we review the evidence that, despite this commonality, polymorphic amino acid differences between allotypes alter the ability of MHC I molecules to change shape (that is, their conformational plasticity). We discuss how the peptide loading co-factor tapasin might modify this plasticity to augment peptide loading. Lastly, we consider recent findings concerning the functions of the non-classical MHC I molecule HLA-E as well as the tapasin-related protein TAPBPR (transporter associated with antigen presentation binding protein-related), which has been shown to act as a second quality-control stage in MHC I antigen presentation. PMID:28299193

  2. 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

  3. Spatial and temporal variation at major histocompatibility complex class IIB genes in the endangered Blakiston's fish owl.

    PubMed

    Kohyama, Tetsuo I; Omote, Keita; Nishida, Chizuko; Takenaka, Takeshi; Saito, Keisuke; Fujimoto, Satoshi; Masuda, Ryuichi

    2015-01-01

    Quantifying intraspecific genetic variation in functionally important genes, such as those of the major histocompatibility complex (MHC), is important in the establishment of conservation plans for endangered species. The MHC genes play a crucial role in the vertebrate immune system and generally show high levels of diversity, which is likely due to pathogen-driven balancing selection. The endangered Blakiston's fish owl (Bubo blakistoni) has suffered marked population declines on Hokkaido Island, Japan, during the past several decades due to human-induced habitat loss and fragmentation. We investigated the spatial and temporal patterns of genetic diversity in MHC class IIβ genes in Blakiston's fish owl, using massively parallel pyrosequencing. We found that the Blakiston's fish owl genome contains at least eight MHC class IIβ loci, indicating recent gene duplications. An analysis of sequence polymorphism provided evidence that balancing selection acted in the past. The level of MHC variation, however, was low in the current fish owl populations in Hokkaido: only 19 alleles were identified from 174 individuals. We detected considerable spatial differences in MHC diversity among the geographically isolated populations. We also detected a decline of MHC diversity in some local populations during the past decades. Our study demonstrated that the current spatial patterns of MHC variation in Blakiston's fish owl populations have been shaped by loss of variation due to the decline and fragmentation of populations, and that the short-term effects of genetic drift have counteracted the long-term effects of balancing selection.

  4. A comparison of common spatial patterns with complex band power features in a four-class BCI experiment.

    PubMed

    Townsend, George; Graimann, Bernhard; Pfurtscheller, Gert

    2006-04-01

    We report on the offline analysis of four-class brain-computer interface (BCI) data recordings. Although the analysis is done within defined time windows (cue-based BCI), our goal is to work toward an approach which classifies on-going electroencephalogram (EEG) signals without the use of such windows (un-cued BCI). To that end, we provide some elements of that analysis related to timing issues that will become important as we pursue this goal in the future. A new set of features called complex band power (CBP) features which make explicit use of phase are introduced and are shown to produce good results. As reference methods we used traditional band power features and the method of common spatial patterns. We consider also for the first time in the context of a four-class problem the issue of variability of the features over time and how much data is required to give good classification results. We do this in a practical way where training data precedes testing data in time.

  5. Proteasome subtypes and regulators in the processing of antigenic peptides presented by class I molecules of the major histocompatibility complex.

    PubMed

    Vigneron, Nathalie; Van den Eynde, Benoît J

    2014-11-18

    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.

  6. 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

  7. Low major histocompatibility complex class II DQA diversity in the Giant Panda (Ailuropoda melanoleuca)

    PubMed Central

    Zhu, Liang; Ruan, Xiang-Dong; Ge, Yun-Fa; Wan, Qiu-Hong; Fang, Sheng-Guo

    2007-01-01

    Background The giant panda (Ailuropoda melanoleuca) is one of the most endangered animals due to habitat fragmentation and loss. Although the captive breeding program for this species is now nearly two decades old, researches on the genetic background of such captive populations, especially on adaptive molecular polymorphism of major histocompatibility complex (MHC), are still limited. In this study, we characterized adaptive variation of the giant panda's MHC DQA gene by PCR amplification of its antigen-recognizing region (i.e. the exon 2) and subsequent single-strand conformational polymorphism (SSCP) and sequence analyses. Results The results revealed a low level of DQA exon 2 diversity in this rare animal, presenting 6 alleles from 61 giant panda individuals. The observed polymorphism was restricted to 9 amino acid substitutions, all of which occurred at and adjacent to positions forming the functionally important antigen-binding sites. All the samples were in Hardy-Weinberg proportions. A significantly higher rate of non-synonymous than synonymous substitutions at the antigen-binding sites indicated positive selection for diversity in the locus. Conclusion The DQA allelic diversity of giant pandas was low relative to other vertebrates. Nonetheless, the pandas exhibited more alleles in DQA than those in DRB, suggesting the alpha chain genes would play a leading role when coping with certain pathogens and thus should be included in conservation genetic investigation. The microsatellite and MHC loci might predict long-term persistence potential and short-term survival ability, respectively. Consequently, it is recommended to utilize multiple suites of microsatellite markers and multiple MHC loci to detect overall genetic variation in order to design unbiased conservation strategies. PMID:17555583

  8. The HOPS/Class C Vps Complex Tethers High-Curvature Membranes via a Direct Protein-Membrane Interaction.

    PubMed

    Ho, Ruoya; Stroupe, Christopher

    2016-10-01

    Membrane tethering is a physical association of two membranes before their fusion. Many membrane tethering factors have been identified, but the interactions that mediate inter-membrane associations remain largely a matter of conjecture. Previously, we reported that the homotypic fusion and protein sorting/Class C vacuolar protein sorting (HOPS/Class C Vps) complex, which has two binding sites for the yeast vacuolar Rab GTPase Ypt7p, can tether two low-curvature liposomes when both membranes bear Ypt7p. Here, we show that HOPS tethers highly curved liposomes to Ypt7p-bearing low-curvature liposomes even when the high-curvature liposomes are protein-free. Phosphorylation of the curvature-sensing amphipathic lipid-packing sensor (ALPS) motif from the Vps41p HOPS subunit abrogates tethering of high-curvature liposomes. A HOPS complex without its Vps39p subunit, which contains one of the Ypt7p binding sites in HOPS, lacks tethering activity, though it binds high-curvature liposomes and Ypt7p-bearing low-curvature liposomes. Thus, HOPS tethers highly curved membranes via a direct protein-membrane interaction. Such high-curvature membranes are found at the sites of vacuole tethering and fusion. There, vacuole membranes bend sharply, generating large areas of vacuole-vacuole contact. We propose that HOPS localizes via the Vps41p ALPS motif to these high-curvature regions. There, HOPS binds via Vps39p to Ypt7p in an apposed vacuole membrane. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. An inherited immunoglobulin class-switch recombination deficiency associated with a defect in the INO80 chromatin remodeling complex

    PubMed Central

    Kracker, Sven; Di Virgilio, Michela; Schwartzentruber, Jeremy; Cuenin, Cyrille; Forveille, Monique; Deau, Marie-Céline; McBride, Kevin M.; Majewski, Jacek; Gazumyan, Anna; Seneviratne, Suranjith; Grimbacher, Bodo; Kutukculer, Necil; Herceg, Zdenko; Cavazzana, Marina; Jabado, Nada; Nussenzweig, Michel C.; Fischer, Alain; Durandy, Anne

    2015-01-01

    Background Immunoglobulin class-switch recombination defects (CSR-D) are rare primary immunodeficiencies characterized by impaired production of switched immunoglobulin isotypes and normal or elevated IgM levels. They are caused by impaired T:B cooperation or intrinsic B cell defects. However, many immunoglobulin CSR-Ds are still undefined at the molecular level. Objective This study's objective was to delineate new causes of immunoglobulin CSR-Ds and thus gain further insights into the process of immunoglobulin class-switch recombination (CSR). Methods Exome sequencing in 2 immunoglobulin CSR-D patients identified variations in the INO80 gene. Functional experiments were performed to assess the function of INO80 on immunoglobulin CSR. Results We identified recessive, nonsynonymous coding variations in the INO80 gene in 2 patients affected by defective immunoglobulin CSR. Expression of wild-type INO80 in patients' fibroblastic cells corrected their hypersensitivity to high doses of γ-irradiation. In murine CH12-F3 cells, the INO80 complex accumulates at Sα and Eμ regions of the IgH locus, and downregulation of INO80 as well as its partners Reptin and Pontin impaired CSR. In addition, Reptin and Pontin were shown to interact with activation-induced cytidine deaminase. Finally, an abnormal separation of sister chromatids was observed upon INO80 downregulation in CH12-F3 cells, pinpointing its role in cohesin activity. Conclusion INO80 deficiency appears to be associated with defective immunoglobulin CSR. We propose that the INO80 complex modulates cohesin function that may be required during immunoglobulin switch region synapsis. PMID:25312759

  10. An inherited immunoglobulin class-switch recombination deficiency associated with a defect in the INO80 chromatin remodeling complex.

    PubMed

    Kracker, Sven; Di Virgilio, Michela; Schwartzentruber, Jeremy; Cuenin, Cyrille; Forveille, Monique; Deau, Marie-Céline; McBride, Kevin M; Majewski, Jacek; Gazumyan, Anna; Seneviratne, Suranjith; Grimbacher, Bodo; Kutukculer, Necil; Herceg, Zdenko; Cavazzana, Marina; Jabado, Nada; Nussenzweig, Michel C; Fischer, Alain; Durandy, Anne

    2015-04-01

    Immunoglobulin class-switch recombination defects (CSR-D) are rare primary immunodeficiencies characterized by impaired production of switched immunoglobulin isotypes and normal or elevated IgM levels. They are caused by impaired T:B cooperation or intrinsic B cell defects. However, many immunoglobulin CSR-Ds are still undefined at the molecular level. This study's objective was to delineate new causes of immunoglobulin CSR-Ds and thus gain further insights into the process of immunoglobulin class-switch recombination (CSR). Exome sequencing in 2 immunoglobulin CSR-D patients identified variations in the INO80 gene. Functional experiments were performed to assess the function of INO80 on immunoglobulin CSR. We identified recessive, nonsynonymous coding variations in the INO80 gene in 2 patients affected by defective immunoglobulin CSR. Expression of wild-type INO80 in patients' fibroblastic cells corrected their hypersensitivity to high doses of γ-irradiation. In murine CH12-F3 cells, the INO80 complex accumulates at Sα and Eμ regions of the IgH locus, and downregulation of INO80 as well as its partners Reptin and Pontin impaired CSR. In addition, Reptin and Pontin were shown to interact with activation-induced cytidine deaminase. Finally, an abnormal separation of sister chromatids was observed upon INO80 downregulation in CH12-F3 cells, pinpointing its role in cohesin activity. INO80 deficiency appears to be associated with defective immunoglobulin CSR. We propose that the INO80 complex modulates cohesin function that may be required during immunoglobulin switch region synapsis. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Are Complex Magnetic Field Structures Responsible for the Confined X-class Flares in Super Active Region 12192?

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Li, Ting; Chen, Huadong

    2017-08-01

    From 2014 October 19 to 27, six X-class flares occurred in super active region (AR) 12192. They were all confined flares and were not followed by coronal mass ejections. To examine the structures of the four flares close to the solar disk center from October 22 to 26, we firstly employ composite triple-time images in each flare process to display the stratified structure of these flare loops. The loop structures of each flare in both the lower (171 Å) and higher (131 Å) temperature channels are complex, e.g., the flare loops rooting at flare ribbons are sheared or twisted (enwound) together, and the complex structures were not destroyed during the flares. For the first flare, although the flare loop system appears as a spindle shape, we can estimate its structures from observations, with lengths ranging from 130 to 300 Mm, heights from 65 to 150 Mm, widths at the middle part of the spindle from 40 to 100 Mm, and shear angles from 16° to 90°. Moreover, the flare ribbons display irregular movements, such as the left ribbon fragments of the flare on October 22 sweeping a small region repeatedly, and both ribbons of the flare on October 26 moved along the same direction instead of separating from each other. These irregular movements also imply that the corresponding flare loops are complex, e.g., several sets of flare loops are twisted together. Although previous studies have suggested that the background magnetic fields prevent confined flares from erupting,based on these observations, we suggest that complex flare loop structures may be responsible for these confined flares.

  12. Distinct functions for the glycans of tapasin and heavy chains in the assembly of major histocompatibility complex (MHC) class I molecules

    PubMed Central

    Rizvi, Syed Monem; Cid, Natasha Del; Lybarger, Lonnie; Raghavan, Malini

    2011-01-01

    Complexes of specific assembly factors and generic endoplasmic reticulum (ER) chaperones collectively called the major histocompatibility complex (MHC) class I peptide loading complex (PLC) function in the folding and assembly of MHC class I molecules. The glycan binding chaperone calreticulin and partner oxidoreductase ERp57 are important in MHC class I assembly, but the sequence of assembly events and specific interactions involved remain incompletely understood. We show that the recruitments of calreticulin and ERp57 to the PLC are co-dependent and also dependent upon the ERp57 binding site and the glycan of the assembly factor tapasin. Furthermore, the ERp57 binding site and the glycan of tapasin enhance β2m and MHC class I heavy chain recruitment to the PLC, with the ERp57 binding site having the dominant effect. On the other hand, the conserved MHC class I heavy chain glycan played a minor role in calreticulin recruitment into the PLC, but impacted the recruitment of heavy chains into the PLC, and glycan-deficient heavy chains were impaired for tapasin-independent and tapasin-assisted assembly. The conserved MHC class I glycan and tapasin facilitated an early step in the assembly of heavy chain-β2m heterodimers, for which tapasin-ERp57 or tapasin-calreticulin complexes were not required. Together, these studies provide insights into how PLCs are constructed, demonstrate two distinct mechanisms by which PLCs can be stabilized, and suggest the presence of intermediate heavy chain-deficient PLCs. PMID:21263072

  13. 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 Central

    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

  14. Bacterial-type Phosphoenolpyruvate Carboxylase (PEPC) Functions as a Catalytic and Regulatory Subunit of the Novel Class-2 PEPC Complex of Vascular Plants*

    PubMed Central

    O'Leary, Brendan; Rao, Srinath K.; Kim, Julia; Plaxton, William C.

    2009-01-01

    Phosphoenolpyruvate carboxylase (PEPC) is a tightly regulated anaplerotic enzyme situated at a major branch point of the plant C metabolism. Two distinct oligomeric classes of PEPC occur in the triglyceride-rich endosperm of developing castor oil seeds (COS). Class-1 PEPC is a typical homotetramer composed of identical 107-kDa plant-type PEPC (PTPC) subunits (encoded by RcPpc3), whereas the novel Class-2 PEPC 910-kDa hetero-octameric complex arises from a tight interaction between Class-1 PEPC and distantly related 118-kDa bacterial-type PEPC (BTPC) polypeptides (encoded by RcPpc4). Here, COS BTPC was expressed from full-length RcPpc4 cDNA in Escherichia coli as an active PEPC that exhibited unusual properties relative to PTPCs, including a tendency to form large aggregates, enhanced thermal stability, a high Km(PEP), and insensitivity to metabolite effectors. A chimeric 900-kDa Class-2 PEPC hetero-octamer having a 1:1 stoichiometry of BTPC:PTPC subunits was isolated from a mixture of clarified extracts containing recombinant RcPPC4 and an Arabidopsis thaliana Class-1 PEPC (the PTPC, AtPPC3). The purified Class-2 PEPC exhibited biphasic PEP saturation kinetics with high and low affinity sites attributed to its AtPPC3 and RcPPC4 subunits, respectively. The RcPPC4 subunits: (i) catalyzed the majority of the Class-2 PEPC Vmax, particularly in the presence of the inhibitor l-malate, and (ii) also functioned as Class-2 PEPC regulatory subunits by modulating PEP binding and catalytic potential of its AtPPC3 subunits. BTPCs appear to associate with PTPCs to form stable Class-2 PEPC complexes in vivo that are hypothesized to maintain high flux from PEP under physiological conditions that would otherwise inhibit Class-1 PEPCs. PMID:19605358

  15. Bacterial-type phosphoenolpyruvate carboxylase (PEPC) functions as a catalytic and regulatory subunit of the novel class-2 PEPC complex of vascular plants.

    PubMed

    O'Leary, Brendan; Rao, Srinath K; Kim, Julia; Plaxton, William C

    2009-09-11

    Phosphoenolpyruvate carboxylase (PEPC) is a tightly regulated anaplerotic enzyme situated at a major branch point of the plant C metabolism. Two distinct oligomeric classes of PEPC occur in the triglyceride-rich endosperm of developing castor oil seeds (COS). Class-1 PEPC is a typical homotetramer composed of identical 107-kDa plant-type PEPC (PTPC) subunits (encoded by RcPpc3), whereas the novel Class-2 PEPC 910-kDa hetero-octameric complex arises from a tight interaction between Class-1 PEPC and distantly related 118-kDa bacterial-type PEPC (BTPC) polypeptides (encoded by RcPpc4). Here, COS BTPC was expressed from full-length RcPpc4 cDNA in Escherichia coli as an active PEPC that exhibited unusual properties relative to PTPCs, including a tendency to form large aggregates, enhanced thermal stability, a high K(m)((PEP)), and insensitivity to metabolite effectors. A chimeric 900-kDa Class-2 PEPC hetero-octamer having a 1:1 stoichiometry of BTPC:PTPC subunits was isolated from a mixture of clarified extracts containing recombinant RcPPC4 and an Arabidopsis thaliana Class-1 PEPC (the PTPC, AtPPC3). The purified Class-2 PEPC exhibited biphasic PEP saturation kinetics with high and low affinity sites attributed to its AtPPC3 and RcPPC4 subunits, respectively. The RcPPC4 subunits: (i) catalyzed the majority of the Class-2 PEPC V(max), particularly in the presence of the inhibitor l-malate, and (ii) also functioned as Class-2 PEPC regulatory subunits by modulating PEP binding and catalytic potential of its AtPPC3 subunits. BTPCs appear to associate with PTPCs to form stable Class-2 PEPC complexes in vivo that are hypothesized to maintain high flux from PEP under physiological conditions that would otherwise inhibit Class-1 PEPCs.

  16. Need for tripeptidyl-peptidase II in major histocompatibility complex class I viral antigen processing when proteasomes are detrimental.

    PubMed

    Guil, Sara; Rodríguez-Castro, Marta; Aguilar, Francisco; Villasevil, Eugenia M; Antón, Luis C; Del Val, Margarita

    2006-12-29

    CD8(+) T lymphocytes recognize infected cells that display virus-derived antigenic peptides complexed with major histocompatibility complex class I molecules. Peptides are mainly byproducts of cellular protein turnover by cytosolic proteasomes. Cytosolic tripeptidyl-peptidase II (TPPII) also participates in protein degradation. Several peptidic epitopes unexpectedly do not require proteasomes, but it is unclear which proteases generate them. We studied antigen processing of influenza virus nucleoprotein epitope NP(147-155), an archetype epitope that is even destroyed by a proteasome-mediated mechanism. TPPII, with the assistance of endoplasmic reticulum trimming metallo-aminopeptidases, probably ERAAP (endoplasmic reticulum aminopeptidase associated with antigen processing), was crucial for nucleoprotein epitope generation both in the presence of functional proteasomes and when blocked by lactacystin, as shown with specific chemical inhibitors and gene silencing. Different protein contexts and subcellular targeting all allowed epitope processing by TPPII as well as trimming. The results show the plasticity of the cell's assortment of proteases for providing ligands for recognition by antiviral CD8(+) T cells. Our observations identify for the first time a set of proteases competent for antigen processing of an epitope that is susceptible to destruction by proteasomes.

  17. Cellular expression and crystal structure of the murine cytomegalovirus major histocompatibility complex class I-like glycoprotein, m153.

    PubMed

    Mans, Janet; Natarajan, Kannan; Balbo, Andrea; Schuck, Peter; Eikel, Daniel; Hess, Sonja; Robinson, Howard; Simic, Hrvoje; Jonjic, Stipan; Tiemessen, Caroline T; Margulies, David H

    2007-11-30

    Mouse cytomegalovirus (MCMV), a beta-herpesvirus that establishes latent and persistent infections in mice, is a valuable model for studying complex virus-host interactions. MCMV encodes the m145 family of putative immunoevasins with predicted major histocompatibility complex, class I (MHC-I) structure. Functions attributed to some family members include down-regulation of host MHC-I (m152) and NKG2D ligands (m145, m152, and m155) and interaction with inhibitory or activating NK receptors (m157). We present the cellular, biochemical, and structural characterization of m153, which is a heavily glycosylated homodimer, that does not require beta2m or peptide and is expressed at the surface of MCMV-infected cells. Its 2.4-A crystal structure confirms that this compact molecule preserves an MHC-I-like fold and reveals a novel mode of dimerization, confirmed by site-directed mutagenesis, and a distinctive disulfide-stabilized extended N terminus. The structure provides a useful framework for comparative analysis of the divergent members of the m145 family.

  18. Major histocompatibility complex class I evolution in songbirds: universal primers, rapid evolution and base compositional shifts in exon 3

    PubMed Central

    Alcaide, Miguel; Liu, Mark

    2013-01-01

    Genes of the Major Histocompatibility Complex (MHC) have become an important marker for the investigation of adaptive genetic variation in vertebrates because of their critical role in pathogen resistance. However, despite significant advances in the last few years the characterization of MHC variation in non-model species still remains a challenging task due to the redundancy and high variation of this gene complex. Here we report the utility of a single pair of primers for the cross-amplification of the third exon of MHC class I genes, which encodes the more polymorphic half of the peptide-binding region (PBR), in oscine passerines (songbirds; Aves: Passeriformes), a group especially challenging for MHC characterization due to the presence of large and complex MHC multigene families. In our survey, although the primers failed to amplify exon 3 from two suboscine passerine birds, they amplified exon 3 of multiple MHC class I genes in all 16 species of oscine songbirds tested, yielding a total of 120 sequences. The 16 songbird species belong to 14 different families, primarily within the Passerida, but also in the Corvida. Using a conservative approach based on the analysis of cloned amplicons (n = 16) from each species, we found between 3 and 10 MHC sequences per individual. Each allele repertoire was highly divergent, with the overall number of polymorphic sites per species ranging from 33 to 108 (out of 264 sites) and the average number of nucleotide differences between alleles ranging from 14.67 to 43.67. Our survey in songbirds allowed us to compare macroevolutionary dynamics of exon 3 between songbirds and non-passerine birds. We found compelling evidence of positive selection acting specifically upon peptide-binding codons across birds, and we estimate the strength of diversifying selection in songbirds to be about twice that in non-passerines. Analysis using comparative methods suggest weaker evidence for a higher GC content in the 3rd codon position of

  19. 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.

  20. IgA class antibodies to 2-oxo-acid dehydrogenase complex are not predictive markers of histopathological progression in primary biliary cirrhosis.

    PubMed

    Omagari, Katsuhisa; Kadokawa, Yoshiko; Nakamura, Minoru; Akazawa, Shiho; Ohba, Kazuo; Ohnita, Ken; Mizuta, Yohei; Daikoku, Manabu; Yatsuhashi, Hiroshi; Ishibashi, Hiromi; Kohno, Shigeru

    2006-03-01

    Although antimitochondrial antibody (AMA) is the characteristic serological feature of primary biliary cirrhosis (PBC), its pathogenic role remains unclear. In our previous study, we reported a positive correlation between immunoglobulin (Ig) A class anti-2-oxo-acid dehydrogenase complex (2-OADC) and histopathological stage. To determine whether the appearance of IgA class anti-2-OADC by immunoblotting represents an early marker of more aggressive disease or whether it is late finding during the disease course of PBC, we tested not only the entire IgA class but also IgA1, IgA2 and secretory IgA class anti-2-OADC in serial serum samples from 15 patients with PBC. During the median observation period of 51 months, four cases showed histopathological progression (from stage 1 to 2, stage 1 to 3, stage 1 to 4 and stage 2 to 4). There was no statistically significant correlation between the above IgA class anti-2-OADCs and histopathological progression. There was no significant correlation between histopathological stages and IgA2 class anti-2-OADC or secretory IgA class anti-2-OADC by immunoblotting. IgA class anti-2-OADC was more frequent in stages 3-4 than in stages 1-2 (p = 0.0049), but IgA1 class anti-2-OADC was more frequent in stages 1-2 than in stages 3-4 (p = 0.0232). Our present study demonstrated that serum IgA class 2-OADC was not a predictive marker of histopathological progression but was associated with the histopathological stage of PBC. Although the IgA class AMA may have a specific pathogenic role for PBC, the discrepant results between IgA and IgA1 class anti-2-OADC should be further assessed to investigate different functional activities depending on their molecular form.

  1. The HOPS/class C Vps complex tethers membranes by binding to one Rab GTPase in each apposed membrane.

    PubMed

    Ho, Ruoya; Stroupe, Christopher

    2015-07-15

    Many Rab GTPase effectors are membrane-tethering factors, that is, they physically link two apposed membranes before intracellular membrane fusion. In this study, we investigate the distinct binding factors needed on apposed membranes for Rab effector-dependent tethering. We show that the homotypic fusion and protein-sorting/class C vacuole protein-sorting (HOPS/class C Vps) complex can tether low-curvature membranes, that is, liposomes with a diameter of ∼100 nm, only when the yeast vacuolar Rab GTPase Ypt7p is present in both tethered membranes. When HOPS is phosphorylated by the vacuolar casein kinase I, Yck3p, tethering only takes place when GTP-bound Ypt7p is present in both tethered membranes. When HOPS is not phosphorylated, however, its tethering activity shows little specificity for the nucleotide-binding state of Ypt7p. These results suggest a model for HOPS-mediated tethering in which HOPS tethers membranes by binding to Ypt7p in each of the two tethered membranes. Moreover, because vacuole-associated HOPS is presumably phosphorylated by Yck3p, our results suggest that nucleotide exchange of Ypt7p on multivesicular bodies (MVBs)/late endosomes must take place before HOPS can mediate tethering at vacuoles. © 2015 Ho and Stroupe. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  2. Inhibition of glucose trimming by castanospermine results in rapid degradation of unassembled major histocompatibility complex class I molecules.

    PubMed

    Moore, S E; Spiro, R G

    1993-02-25

    The CMT-cKd1 cell line provides a system for studying the initial processing steps of N-linked oligosaccharides as these cells have been shown to produce major histocompatibility complex (MHC) class I molecules which, due to a defect in assembly, recycle between the endoplasmic reticulum and a pre-Golgi compartment, failing to reach the cell surface (Hsu, V.W., Yuan, L. C., Nuchtern, J. G., Lippincott-Schwartz, J., Hämmerling, G. J., and Klausner, R. D. (1991) Nature 352, 441-444). In the present study we observed that when the MHC class I heavy chain of these CMT cells was pulse-radiolabeled with [35S]methionine in the presence of the glucosidase inhibitor, castanospermine (CST), it underwent a rapid degradation during a 60-min chase, in contrast to control cells in which it remained stable during that period. The CST-promoted instability of the MHC molecule appeared to be specific, as it did not occur when 1-deoxymannojirimycin, an inhibitor of mannosidase, was added to the cells. Although endomannosidase was found to be present in the CMT cells, the electrophoretic mobility of the MHC heavy chain produced in the presence of CST indicated that deglucosylation through the alternate route provided by this enzyme did not occur. Furthermore, gamma-interferon did not prevent the rapid disappearance of the MHC molecule, although it brought about entry of this glycoprotein into the secretory pathway in cells incubated without CST. The results of our studies suggest that retention of glucose on N-linked oligosaccharides may under certain circumstances provide a signal for pre-Golgi protein degradation.

  3. 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

  4. Complex Structure in Class 0 Protostellar Envelopes. II. Kinematic Structure from Single-dish and Interferometric Molecular Line Mapping

    NASA Astrophysics Data System (ADS)

    Tobin, John J.; Hartmann, Lee; Chiang, Hsin-Fang; Looney, Leslie W.; Bergin, Edwin A.; Chandler, Claire J.; Masqué, Josep M.; Maret, Sébastien; Heitsch, Fabian

    2011-10-01

    We present a study of dense molecular gas kinematics in 17 nearby protostellar systems using single-dish and interferometric molecular line observations. The non-axisymmetric envelopes around a sample of Class 0/I protostars were mapped in the N2H+ (J = 1 → 0) tracer with the IRAM 30 m, CARMA, and Plateau de Bure Interferometer, as well as NH3 (1,1) with the Very Large Array. The molecular line emission is used to construct line-center velocity and linewidth maps for all sources to examine the kinematic structure in the envelopes on spatial scales from 0.1 pc to ~1000 AU. The direction of the large-scale velocity gradients from single-dish mapping is within 45° of normal to the outflow axis in more than half the sample. Furthermore, the velocity gradients are often quite substantial, the average being ~2.3 km s-1 pc-1. The interferometric data often reveal small-scale velocity structure, departing from the more gradual large-scale velocity gradients. In some cases, this likely indicates accelerating infall and/or rotational spin-up in the inner envelope; the median velocity gradient from the interferometric data is ~10.7 km s-1 pc-1. In two systems, we detect high-velocity HCO+ (J = 1 → 0) emission inside the highest-velocity N2H+ emission. This enables us to study the infall and rotation close to the disk and estimate the central object masses. The velocity fields observed on large and small scales are more complex than would be expected from rotation alone, suggesting that complex envelope structure enables other dynamical processes (i.e., infall) to affect the velocity field. Based on observations carried out with the IRAM 30 m Telescope and IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

  5. 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.

  6. Polymorphism in a second ABC transporter gene located within the class II region of the human major histocompatibility complex.

    PubMed Central

    Powis, S H; Mockridge, I; Kelly, A; Kerr, L A; Glynne, R; Gileadi, U; Beck, S; Trowsdale, J

    1992-01-01

    Recent studies have identified genes within the major histocompatibility complex (MHC) that may play a role in presentation of antigenic peptides to T cells. We have previously described RING4, a gene within the human MHC class II region that has sequence homology with members of the ABC ("ATP-binding cassette") transporter superfamily. We now report the nucleotide sequence of RING11, a second ABC transporter gene located approximately 7 kilobases telomeric to RING4, RING11 is gamma-interferon inducible, a property shared with other genes involved in antigen presentation. Comparison between the amino acid sequences of RING11 and RING4 reveals strong homology. We propose that they form a heterodimer that transports peptides from the cytoplasm into the endoplasmic reticulum. We have identified two RING11 alleles, which differ in the length of their derived protein sequence by 17 amino acids. The more common of these alleles is present in a Caucasoid population at a frequency of 79%. Images PMID:1741401

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. A single nomenclature and associated database for alleles at the major histocompatibility complex class II DRB1 locus of sheep.

    PubMed

    Ballingall, K T; Herrmann-Hoesing, L; Robinson, J; Marsh, S G E; Stear, M J

    2011-06-01

    The development of standardised nomenclatures with associated databases containing reference sequences for alleles at polymorphic loci within the major histocompatibility complex (MHC) has been facilitated by the development of the immuno polymorphism database (IPD). Recently, included within IPD-MHC is information on allelic diversity within sheep species (IPD-MHC-OLA). Here, we present the first report of progress in populating the sheep IPD-MHC database with alleles at the class II MHC DRB1 locus. The sequence of 63 Ovar-DRB1 alleles within 24 allelic families is now held within the database, each meeting the minimum requirement of a complete second exon. These sequences are derived from a combination of genomic and cDNA-based approaches and represent the most extensive collection of validated alleles at the sheep DRB1 locus yet described. Although these 63 alleles probably represent only a fraction of the DRB1 allelic diversity in sheep species worldwide, we encourage the research community to use the official allelic nomenclature and to contribute allelic sequences to the database via its web-based submission tool. In time, the IPD-MHC-OLA resource will underpin population-based MHC genotyping studies and help to simplify meta-analyses of multi-source data from wild and domestic sheep populations.

  12. Major histocompatibility complex class I molecules protect motor neurons from astrocyte-induced toxicity in amyotrophic lateral sclerosis.

    PubMed

    Song, SungWon; Miranda, Carlos J; Braun, Lyndsey; Meyer, Kathrin; Frakes, Ashley E; Ferraiuolo, Laura; Likhite, Shibi; Bevan, Adam K; Foust, Kevin D; McConnell, Michael J; Walker, Christopher M; Kaspar, Brian K

    2016-04-01

    Astrocytes isolated from individuals with amyotrophic lateral sclerosis (ALS) are toxic to motor neurons (MNs) and play a non-cell autonomous role in disease pathogenesis. The mechanisms underlying the susceptibility of MNs to cell death remain unclear. Here we report that astrocytes derived from either mice bearing mutations in genes associated with ALS or human subjects with ALS reduce the expression of major histocompatibility complex class I (MHCI) molecules on MNs; reduced MHCI expression makes these MNs susceptible to astrocyte-induced cell death. Increasing MHCI expression on MNs increases survival and motor performance in a mouse model of ALS and protects MNs against astrocyte toxicity. Overexpression of a single MHCI molecule, HLA-F, protects human MNs from ALS astrocyte-mediated toxicity, whereas knockdown of its receptor, the killer cell immunoglobulin-like receptor KIR3DL2, on human astrocytes results in enhanced MN death. Thus, our data indicate that, in ALS, loss of MHCI expression on MNs renders them more vulnerable to astrocyte-mediated toxicity.

  13. 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.

  14. Human endogenous retrovirus type I-related viruses have an apparently widespread distribution within vertebrates.

    PubMed Central

    Martin, J; Herniou, E; Cook, J; Waugh O'Neill, R; Tristem, M

    1997-01-01

    Retroviruses from lower vertebrate hosts have been poorly characterized to date. Few sequences have been isolated, and those which have been reported are all highly divergent when compared to the retroviruses known to be harbored by mammals and birds. Here we show that retroviruses with significant homology to the human endogenous retrovirus type I (HERV-I) are present within the genomes of fish, reptiles, birds, and mammals and that they may well be widespread within many vertebrates. Phylogenetic analysis of nucleotide sequences strongly supported the inclusion of viruses from each of these vertebrate classes into one monophyletic group. This analysis also demonstrated that the HERV-I-related viruses are more closely related to retroviruses belonging to the murine leukemia virus genus than to members of the other retroviral genera. The presence of HERV-I-related retroviruses in so many disparate vertebrate hosts suggests that other endogenous human retroviruses may also have a much wider distribution than is currently appreciated. PMID:8985368

  15. Perceptual complexity and form class cues in novel word extension tasks: how 4-year-old children interpret adjectives and count nouns.

    PubMed

    Sandhofer, Catherine M; Smith, Linda B

    2004-06-01

    Two experiments examined the role of perceptual complexity, object familiarity and form class cues on how children interpret novel adjectives and count nouns. Four-year-old children participated in a forced-choice match-to-target task in which an exemplar was named with a novel word and children were asked to choose another one that matched the exemplar in either shape or material In experiment 1, 56 children were provided with lexical form class cues suggestive of adjectives. The results of Experiment 1 showed that perceptual complexity and not object familiarity determined whether children made material or shape matches. In Experiment 2, 56 children were provided with lexical form class cues suggestive of count nouns. The results of Experiment 2 showed that neither perceptual complexity nor object familiarity affected children's selections in the matching task. When provided with lexical form class cues suggestive of a count noun, children selected shape matches. Thus the results suggest that the perceptual properties of the objects presented to children coupled with the particular lexical form class cue determine which features of objects children attend to when interpreting novel words.

  16. Graft-versus-host resistance induced by class II major histocompatibility complex-specific T cell clones

    PubMed Central

    1991-01-01

    Possible mechanisms of graft-vs.-host (GVH) resistance have been studied using a panel of seven class II major histocompatibility complex-specific T cell clones for elicitation and challenge. One clone recognized I-Ak,d,f, and expressed V beta 8.3 together with J beta 1.5. The remaining six clones were I-Ek specific and expressed V beta 15 rearranged to J beta 1.1 or J beta 1.3. The I-Ek-specific clones were also homologous to each other and different from the I-A-reactive one in the D and N regions. Four of the seven clones exhibited I-Ek- specific cytolytic activity. Each clone, when injected in sublethal numbers into appropriate recipients, could induce resistance to a subsequent lethal dose of any other clone in the panel. The resistance did not require sharing of either T cell receptor beta chains or antigen specificity, or MHC molecules by the eliciting and challenging clone. Cytolytic and noncytolytic clones were equally efficient in inducing GVH resistance. A prerequisite of resistance induction was the activation of eliciting clone subsequent to recognition of class II molecules in the host. Clones preactivated with high concentrations of recombinant interleukin 2, in vitro, could induce GVH resistance also in syngeneic hosts, suggesting that resistance induction was associated with the activated state of clone, rather than antigen recognition per se. In all instances of resistance, the challenging clones failed to induce vascular leakage, which was the cause of death in susceptible recipients (Lehmann, P. V., G. Schumm, D. Moon, U. Hurtenbach, F. Falcioni, S. Muller, and Z. A. Nagy. 1990. J. Exp. Med. 171:1485). Lipopolysaccharide (LPS) induced resistance to vascular leakage did not provide crossresistance to GVH and vice versa, suggesting that interleukin 1 alpha and tumor necrosis factor alpha implicated in LPS resistance are not involved in GVH resistance. Although the mechanism remains unclear, the most likely explanation for GVH resistance in this

  17. Consequences of cytotoxic T lymphocyte interaction with major histocompatibility complex class I-expressing neurons in vivo

    PubMed Central

    1995-01-01

    Neurons have evolved strategies to evade immune surveillance that include an inability to synthesize the heavy chain of the class I major histocompatibility complex (MHC), proteins that are necessary for cytotoxic T lymphocyte (CTL) recognition of target cells. Multiple viruses have taken advantage of the lack of CTL-mediated recognition and killing of neurons by establishing persistent neuronal infections and thereby escaping attack by antiviral CTL. We have expressed a class I MHC molecule (Db) in neurons of transgenic mice using the neuron- specific enolase (NSE) promoter to determine the pathogenic consequences of CTL recognition of virally infected, MHC-expressing central nervous system (CNS) neurons. The NSE-Db transgene was expressed in H-2b founder mice, and transgene-derived messenger RNA was detected by reverse transcriptase-polymerase chain reaction in transgenic brains from several lines. Purified primary neurons from transgenic but not from nontransgenic mice adhered to coverslips coated with a conformation-dependent monoclonal antibody directed against the Dv molecule and presented viral peptide to CTL in an MHC-restricted manner, indicating that the Db molecule was expressed on transgenic neurons in a functional form. Transgenic mice infected with the neurotropic lymphocytic choriomeningitis virus (LCMV) and given anti- LCMV, MHC-restricted CTL displayed a high morbidity and mortality when compared with controls receiving MHC-mismatched CTL or expressing alternative transgenes. After CTL transfer, transgenic brains showed an increased number of CD8+ cells compared with nontransgenic controls as well as an increased rate of clearance of infectious virus from the CNS. Additionally, an increase in blood-brain barrier permeability was detected during viral clearance in NSE-Db transgenic mice and lasted several months after clearance of virus from neurons. In contrast, LCMV- infected, nontransgenic littermates and mice expressing other gene products from

  18. Implementing a Case-Based E-Learning Environment in a Lecture-Oriented Anaesthesiology Class: Do Learning Styles Matter in Complex Problem Solving over Time?

    ERIC Educational Resources Information Center

    Choi, Ikseon; Lee, Sang Joon; Kang, Jeongwan

    2009-01-01

    This study explores how students' learning styles influence their learning while solving complex problems when a case-based e-learning environment is implemented in a conventional lecture-oriented classroom. Seventy students from an anaesthesiology class at a dental school participated in this study over a 3-week period. Five learning-outcome…

  19. Structural and Biochemical Analyses of Swine Major Histocompatibility Complex Class I Complexes and Prediction of the Epitope Map of Important Influenza A Virus Strains

    PubMed Central

    Fan, Shuhua; Wu, Yanan; Wang, Song; Wang, Zhenbao; Jiang, Bo; Liu, Yanjie; Liang, Ruiying; Zhou, Wenzhong

    2016-01-01

    ABSTRACT The lack of a peptide-swine leukocyte antigen class I (pSLA I) complex structure presents difficulties for the study of swine cytotoxic T lymphocyte (CTL) immunity and molecule vaccine development to eliminate important swine viral diseases, such as influenza A virus (IAV). Here, after cloning and comparing 28 SLA I allelic genes from Chinese Heishan pigs, pSLA-3*hs0202 was crystalized and solved. SLA-3*hs0202 binding with sβ2m and a KMNTQFTAV (hemagglutinin [HA]-KMN9) peptide from the 2009 pandemic swine H1N1 strain clearly displayed two distinct conformations with HA-KMN9 peptides in the structures, which are believed to be beneficial to stimulate a broad spectrum of CTL immune responses. Notably, we found that different HA-KMN9 conformations are caused, not only by the flexibility of the side chains of residues in the peptide-binding groove (PBG), but also by the skewing of α1 and α2 helixes forming the PBG. In addition, alanine scanning and circular-dichroism (CD) spectra confirmed that the B, D, and F pockets play critical biochemical roles in determining the peptide-binding motif of SLA-3*hs0202. Based on biochemical parameters and comparisons to similar pockets in other known major histocompatibility complex class I (MHC-I) structures, the fundamental motif for SLA-3*hs0202 was determined to be X-(M/A/R)-(N/Q/R/F)-X-X-X-X-X-(V/I) by refolding in vitro and multiple mutant peptides. Finally, 28 SLA-3*hs0202-restricted epitope candidates were identified from important IAV strains, and two of them have been found in humans as HLA-A*0201-specific IAV epitopes. Structural and biochemical illumination of pSLA-3*hs0202 can benefit vaccine development to control IAV in swine. IMPORTANCE We crystalized and solved the first SLA-3 structure, SLA-3*hs0202, and found that it could present the same IAV peptide with two distinct conformations. Unlike previous findings showing that variable peptide conformations are caused only by the flexibility of the side

  20. 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.

  1. Selective abrogation of major histocompatibility complex class II expression on extrahematopoietic cells in mice lacking promoter IV of the class II transactivator gene.

    PubMed

    Waldburger, J M; Suter, T; Fontana, A; Acha-Orbea, H; Reith, W

    2001-08-20

    MHC class II (MHCII) molecules play a pivotal role in the induction and regulation of immune responses. The transcriptional coactivator class II transactivator (CIITA) controls MHCII expression. The CIITA gene is regulated by three independent promoters (pI, pIII, pIV). We have generated pIV knockout mice. These mice exhibit selective abrogation of interferon (IFN)-gamma-induced MHCII expression on a wide variety of non-bone marrow-derived cells, including endothelia, epithelia, astrocytes, and fibroblasts. Constitutive MHCII expression on cortical thymic epithelial cells, and thus positive selection of CD4(+) T cells, is also abolished. In contrast, constitutive and inducible MHCII expression is unaffected on professional antigen-presenting cells, including B cells, dendritic cells, and IFN-gamma-activated cells of the macrophage lineage. pIV(-/-) mice have thus allowed precise definition of CIITA pIV usage in vivo. Moreover, they represent a unique animal model for studying the significance and contribution of MHCII-mediated antigen presentation by nonprofessional antigen-presenting cells in health and disease.

  2. 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.

  3. Association of Major Histocompatibility Complex Class I Haplotypes with Disease Progression after Simian Immunodeficiency Virus Challenge in Burmese Rhesus Macaques

    PubMed Central

    Nomura, Takushi; Yamamoto, Hiroyuki; Shiino, Teiichiro; Takahashi, Naofumi; Nakane, Taku; Iwamoto, Nami; Ishii, Hiroshi; Tsukamoto, Tetsuo; Kawada, Miki; Matsuoka, Saori; Takeda, Akiko; Terahara, Kazutaka; Tsunetsugu-Yokota, Yasuko; Iwata-Yoshikawa, Naoko; Hasegawa, Hideki; Sata, Tetsutaro; Naruse, Taeko K.; Kimura, Akinori

    2012-01-01

    Nonhuman primate AIDS models are essential for the analysis of AIDS pathogenesis and the evaluation of vaccine efficacy. Multiple studies on human immunodeficiency virus and simian immunodeficiency virus (SIV) infection have indicated the association of major histocompatibility complex class I (MHC-I) genotypes with rapid or slow AIDS progression. The accumulation of macaque groups that share not only a single MHC-I allele but also an MHC-I haplotype consisting of multiple polymorphic MHC-I loci would greatly contribute to the progress of AIDS research. Here, we investigated SIVmac239 infections in four groups of Burmese rhesus macaques sharing individual MHC-I haplotypes, referred to as A, E, B, and J. Out of 20 macaques belonging to A+ (n = 6), E+ (n = 6), B+ (n = 4), and J+ (n = 4) groups, 18 showed persistent viremia. Fifteen of them developed AIDS in 0.5 to 4 years, with the remaining three at 1 or 2 years under observation. A+ animals, including two controllers, showed slower disease progression, whereas J+ animals exhibited rapid progression. E+ and B+ animals showed intermediate plasma viral loads and survival periods. Gag-specific CD8+ T-cell responses were efficiently induced in A+ animals, while Nef-specific CD8+ T-cell responses were in A+, E+, and B+ animals. Multiple comparisons among these groups revealed significant differences in survival periods, peripheral CD4+ T-cell decline, and SIV-specific CD4+ T-cell polyfunctionality in the chronic phase. This study indicates the association of MHC-I haplotypes with AIDS progression and presents an AIDS model facilitating the analysis of virus-host immune interaction. PMID:22491464

  4. 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.

  5. Genetic Variation on the BAT1-NFKBIL1-LTA Region of Major Histocompatibility Complex Class III Associates with Periodontitis

    PubMed Central

    Marchesani, Marja; Vlachopoulou, Efthymia; Mäntylä, Päivi; Paju, Susanna; Buhlin, Kåre; Suominen, Anna L.; Contreras, Johanna; Knuuttila, Matti; Hernandez, Marcela; Huumonen, Sisko; Nieminen, Markku S.; Perola, Markus; Sinisalo, Juha; Lokki, Marja-Liisa; Pussinen, Pirkko J.

    2014-01-01

    Periodontitis is a chronic inflammatory disease with a multifactorial etiology. We investigated whether human major histocompatibility complex (MHC) polymorphisms (6p21.3) are associated with periodontal parameters. Parogene 1 population samples (n = 169) were analyzed with 13,245 single nucleotide polymorphisms (SNPs) of the MHC region. Eighteen selected SNPs (P ≤ 0.001) were replicated in Parogene 2 population samples (n = 339) and the Health 2000 Survey (n = 1,420). All subjects had a detailed clinical and radiographic oral health examination. Serum lymphotoxin-α (LTA) concentrations were measured in the Parogene populations, and the protein was detected in inflamed periodontal tissue. In the Parogene 1 population, 10 SNPs were associated with periodontal parameters. The strongest associations emerged from the parameters bleeding on probing (BOP) and a probing pocket depth (PPD) of ≥6 mm with the genes BAT1, NFKBIL1, and LTA. Six SNPs, rs11796, rs3130059, rs2239527, rs2071591, rs909253, and rs1041981 (r2, ≥0.92), constituted a risk haplotype. In the Parogene 1 population, the haplotype had the strongest association with the parameter BOP, a PPD of ≥6 mm, and severe periodontitis with odds ratios (95% confidence intervals) of 2.63 (2.21 to 3.20), 2.90 (2.37 to 3.52), and 3.10 (1.63 to 5.98), respectively. These results were replicated in the other two populations. High serum LTA concentrations in the Parogene population were associated with the periodontitis risk alleles of the LTA SNPs (rs909253 and rs1041981) of the haplotype. In addition, the protein was expressed in inflamed gingival connective tissue. We identified a novel BAT1-NFKBIL1-LTA haplotype as a significant contributor to the risk of periodontitis. The genetic polymorphisms in the MHC class III region may be functionally important in periodontitis susceptibility. PMID:24566624

  6. Class III phosphoinositide 3-kinase--Beclin1 complex mediates the amino acid-dependent regulation of autophagy in C2C12 myotubes.

    PubMed Central

    Tassa, Amina; Roux, Marie Paule; Attaix, Didier; Bechet, Daniel M

    2003-01-01

    Increased proteolysis contributes to muscle atrophy that prevails in many diseases. Elucidating the signalling pathways responsible for this activation is of obvious clinical importance. Autophagy is a ubiquitous degradation process, induced by amino acid starvation, that delivers cytoplasmic components to lysosomes. Starvation markedly stimulates autophagy in myotubes, and the present studies investigate the mechanisms of this regulation. In C(2)C(12) myotubes incubated with serum growth factors, amino acid starvation stimulated autophagic proteolysis independently of p38 and p42/p44 mitogen-activated protein kinases, but in a PI3K (phosphoinositide 3-kinase)-dependent manner. Starvation, however, did not alter activities of class I and class II PI3Ks, and was not sufficient to affect major signalling proteins downstream from class I PI3K (glycogen synthase kinase, Akt/protein kinase B and protein S6). In contrast, starvation increased class III PI3K activity in whole-myotube extracts. In fact, this increase was most pronounced for a population of class III PI3K that coimmunoprecipitated with Beclin1/Apg6 protein, a major determinant in the initiation of autophagy. Stimulation of proteolysis was reproduced by feeding myotubes with synthetic dipalmitoyl-PtdIns3 P, the class III PI3K product. Conversely, protein transfection of anti-class III PI3K inhibitory antibody into starved myotubes inverted the induction of proteolysis. Therefore, independently of class I PI3K/Akt, protein S6 and mitogen-activated protein kinase pathways, amino acid starvation stimulates proteolysis in myotubes by regulating class III PI3K-Beclin1 autophagic complexes. PMID:12967324

  7. 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.

  8. Correlation between histopathological findings of the liver and IgA class antibodies to 2-oxo-acid dehydrogenase complex in primary biliary cirrhosis.

    PubMed

    Masuda, Jun-Ichi; Omagari, Katsuhisa; Ohba, Kazuo; Hazama, Hiroaki; Kadokawa, Yoshiko; Kinoshita, Hideki; Hayashida, Kenji; Hayashida, Kazuhiro; Ishibashi, Hiromi; Nakanuma, Yasuni; Kohno, Shigeru

    2003-05-01

    Although anti-mitochondrial antibody (AMA) is the characteristic serological feature of primary biliary cirrhosis (PBC), its pathogenetic role remains unclear. We tested sera from 72 Japanese patients with histologically confirmed PBC for AMA by indirect immunofluorescence, anti-pyruvate dehydrogenase complex (PDC) by enzyme inhibition assay, immunoglobulin (Ig) G class anti-PDC by ELISA, and IgG, IgM, and IgA class anti-2-oxo-acid dehydrogenase complex (2-OADC) by immunoblotting. Of the 72 sera, 60 (83%), 50 (69%), 42 (58%), and 71 (99%) were positive for AMA by immunofluorescence, enzyme inhibition assay, ELISA, and immunoblotting, respectively. There was no significant correlation between histological stages and AMA by immunofluorescence, PDC inhibitory antibodies by enzyme inhibition assay, IgG class anti-PDC antibodies by ELISA, or IgG and IgM class anti-2-OADC by immunoblotting. IgA class anti-2-OADC by immunoblotting was more frequent in stages 2-4 than in stage 1 (P = 0.0083). Of the IgA class anti-2-OADC, anti-PDC-E2 (74 kDa) and anti-E3BP (52 kDa) were more frequent in stages 2-4 than in stage 1 (P = 0.0253 and 0.0042, respectively). Further examination of histopathological findings in 53 of 72 liver biopsy specimens showed that IgA class anti-PDC-E2 and IgA class anti-E3BP were associated with bile duct loss, and IgA class anti-PDC-E2 was also associated with interface hepatitis and atypical ductular proliferation. IgA is known to be secreted into the bile through biliary epithelial cells, implying that IgA class anti-PDC-E2 and E3BP may have a specific pathogenetic role during their transport into the bile by binding to their target antigen(s) in biliary epithelial cells, and this may be followed by dysfunction and finally destruction of biliary epithelial cells. Our present results suggest that these autoantibodies against 2-OADC detected by immunoblotting may be associated with the pathogenesis and pathologic progression of PBC.

  9. Selection of lowly immunogenic and highly tolerogenic donor and recipient allochimeric class I major histocompatibility complex proteins.

    PubMed

    Perez, John; Stepkowski, Stanislaw M; Song, Ping; Trawick, Barton; Wang, Mou-Er; Janczewska, Slawa; Kahan, Barry D

    2003-10-27

    Ten different highly polymorphic amino acids (AAs) are located in the alpha1 (alpha1h) and alpha2 (alpha2h) helical regions of the class I major histocompatibility complex RT1. An rat alloantigen. We examined the potential of alpha1h-RT1. An versus alpha2h-RT1. An polymorphic AAs to induce accelerated rejection or tolerance of heart allografts. The allochimeric alpha1h52-90n-RT1.Ac and alpha2h148-179n-RT1.Ac cDNAs were produced by the substitution of nucleotides encoding recipient RT1.Ac AAs for donor RT1. An AAs. Allochimeric and wild-type (WT)-RT1. An proteins were generated in an Escherichia coli expression system. A single portal vein administration of 100 mug alpha1h52-90n-RT1.Ac protein in combination with a 7-day course of oral cyclosporine A (4 mg/kg) induced tolerance to Brown Norway (BN) (RT1n) heart allografts in PVG (RT1c) recipients more effectively than did WT-RT1. An protein; alpha2h148-179n-RT1.Ac protein was ineffective. However, subcutaneous injection of 100 mug WT-RT1. An (but neither alpha1h52-90n-RT1.Ac nor alpha2h148-179n-RT1.Ac) protein induced accelerated rejection of BN heart allografts. Untreated PVG recipients of BN heart allografts displayed activation of both interleukin (IL)-2- and interferon-gamma-producing T helper (Th) 1 cells and IL-4- and IL-10-producing Th2 cells on days 5, 7, and 14 postgrafting, as measured by an enzyme-linked immunospot assay. In contrast, in comparison with rejectors, tolerant recipients showed down-regulation of Th1 cells and up-regulation of Th2 cells on days 5, 7, 14, and 200 postgrafting. Histology of heart allografts showed that tolerant BN heart allografts had no evidence of acute or chronic rejection when examined on day 100 after transplantation. The poorly immunogenic alpha1h52-90n-RT1.Ac allochimeric protein induces tolerance by selective activation of regulatory Th2 cells.

  10. Coexpression of intercellular adhesion molecule-1 and class I major histocompatibility complex antigens on hepatocyte membrane in chronic viral hepatitis.

    PubMed Central

    Chu, C M; Liaw, Y F

    1993-01-01

    AIMS--To evaluate the role of hepatocyte expression of leucocyte adhesion molecules and major histocompatibility complex (MHC) antigens in the pathogenesis of chronic viral hepatitis. METHODS--The expression of intercellular adhesion molecule 1 (ICAM-1), lymphocyte function associated antigen 3 (LFA-3), and MHC class I and II antigens on hepatocyte membrane in relation to the histological and biochemical activities was studied in patients with chronic B hepatitis, chronic persistent hepatitis (CPH) n = 23; chronic active hepatitis (CAH) n = 20; chronic D hepatitis (CAH) n = 6; and chronic non-A, non-B hepatitis (CPH n = 4, CAM n = 6). Six of the latter were hepatitis C virus antibody positive. RESULTS--In chronic B hepatitis ICAM-1 and MHC-I were expressed significantly more in patients with CAH than in those with CPH (p < 0.001), while the expression of LFA-3 and MHC-II showed no significant difference, irrespective of serum HBeAg or hepatitis B virus DNA. Similar findings were noted in non-A, non-B hepatitis. Regardless of the viral aetiology, patients with CAH had a significantly higher degree of ICAM-1 and MHC-I expression than LFA-3 (p < 0.001 v ICAM-1 and MHC-I, respectively) and MHC-II (p < 0.001 v ICAM-1 and MHC-I, respectively) expression. Those with CPH showed little or no difference in the expression of these four molecules. Furthermore, serum ALT values positively correlated with the hepatocyte expression of ICAM-1 (p < 0.001) and MHC-I (p < 0.001), but not LFA-3 (p > 0.05) and MHC-II (p > 0.05). CONCLUSIONS--In chronic viral hepatitis hepatocyte expression of ICAM-1 and MHC-I might be important for immunosurveillance against virally infected hepatocytes, while the expression of LFA-3 and MHC-II does not seem to have a role in the pathogenesis of chronic viral hepatitis. Images PMID:7902850

  11. Major Histocompatibility Complex Class II Dextramers: New Tools for the Detection of antigen-Specific, CD4 T Cells in Basic and Clinical Research.

    PubMed

    Massilamany, C; Krishnan, B; Reddy, J

    2015-11-01

    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. © 2015 The Foundation for the Scandinavian Journal of Immunology.

  12. Evidence that transporters associated with antigen processing translocate a major histocompatibility complex class I-binding peptide into the endoplasmic reticulum in an ATP-dependent manner.

    PubMed Central

    Androlewicz, M J; Anderson, K S; Cresswell, P

    1993-01-01

    We have investigated the role of the putative peptide transporters associated with antigen processing (TAP) by using a permeabilized-cell system. The main objective was to determine whether these molecules, which bear homology to the ATP-binding cassette family of transporters, translocate antigenic peptides across the endoplasmic reticulum membrane for assembly with major histocompatibility complex (MHC) class I molecules and beta 2-microglobulin light chain. The pore-forming toxin streptolysin O was used to generate permeabilized cells, and peptide translocation was determined by measuring the amount of added radiolabeled peptide bound to endogenous class I molecules. No radiolabeled peptide was associated with MHC class I glycoproteins from unpermeabilized cells. We found that efficient peptide binding to MHC class I molecules in permeabilized cells is both transporter dependent and ATP dependent. In antigen-processing mutant cells lacking a functional transporter, uptake occurs only through a less-efficient transporter and ATP-independent pathway. In addition, short peptides (8-10 amino acids) known to bind MHC class I molecules compete efficiently with a radiolabeled peptide for TAP-dependent translocation, whereas longer peptides and a peptide derived from an endoplasmic reticulum signal sequence do not compete efficiently. This result indicates that the optimal substrates for TAP possess the characteristics of MHC-binding peptides. Images Fig. 2 Fig. 3 Fig. 4 PMID:8415666

  13. 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

  14. Allospecific cytotoxic T lymphocytes recognize an H-2 peptide in the context of a murine major histocompatibility complex class I molecule.

    PubMed Central

    Song, E S; Linsk, R; Olson, C A; McMillan, M; Goodenow, R S

    1988-01-01

    We have isolated cytotoxic T lymphocytes (CTL) preferentially reactive with the alpha 1 external domain of the H-2Ld antigen by selecting for T cells capable of recognizing a variant major histocompatibility complex (MHC) class I antigen sharing alpha 1 sequences with H-2Ld. Using these CTL, we demonstrate that a synthetic alpha 1 peptide corresponding to one of the helices derived from the H-2Ld molecule can be presented by a class I restriction element to reconstitute a CTL determinant borne by intact H-2Ld. Moreover, several other H-2L-reactive CTL generated independently were also able to recognize H-2Ld either as an intact alloantigen or as a peptide in conjunction with appropriate class I restriction elements. These data demonstrate that an H-2 peptide can reconstitute a CTL target structure and suggest that some alloreactive T cells in fact might be directed against allogeneic class I peptides in the context of a class I framework. PMID:3258067

  15. Crystal structure of the human CD4 N-terminal two-domain fragment complexed to a class II MHC molecule.

    SciTech Connect

    Wang, J.-H.; Meijers, R.; Xiong, Y.; Liu, J.-H.; Sakihama, T.; Zhang, R.-G.; Joachimiak, A.; Reinherz, E. L.; Biosciences Division; Dana-Farber Cancer Inst.; Harvard Medical School

    2001-09-11

    The structural basis of the interaction between the CD4 coreceptor and a class II major histocompatibility complex (MHC) is described. The crystal structure of a complex containing the human CD4 N-terminal two-domain fragment and the murine I-A{sup k }class II MHC molecule with associated peptide (pMHCII) shows that only the 'top corner' of the CD4 molecule directly contacts pMHCII. The CD4 Phe-43 side chain extends into a hydrophobic concavity formed by MHC residues from both {alpha}2 and {beta}2 domains. A ternary model of the CD4-pMHCII-T-cell receptor (TCR) reveals that the complex appears V-shaped with the membrane-proximal pMHCII at the apex. This configuration excludes a direct TCR-CD4 interaction and suggests how TCR and CD4 signaling is coordinated around the antigenic pMHCII complex. Human CD4 binds to HIV gp120 in a manner strikingly similar to the way in which CD4 interacts with pMHCII. Additional contacts between gp120 and CD4 give the CD4-gp120 complex a greater affinity. Thus, ligation of the viral envelope glycoprotein to CD4 occludes the pMHCII-binding site on CD4, contributing to immunodeficiency.

  16. 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.

  17. 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…

  18. Association of the bovine leukocyte antigen major histocompatibility complex class II DRB3*4401 allele with host resistance to the Lone Star tick, Amblyomma americanum.

    PubMed

    Untalan, Pia M; Pruett, John H; Steelman, C Dayton

    2007-04-10

    The MHC of cattle, known as the bovine leukocyte antigen (BoLA) complex, plays an integral role in disease and parasite susceptibility, and immune responsiveness of the host. While susceptibility to tick infestation in cattle is believed to be heritable, genes that may be responsible for the manifestation of this phenotype remain elusive. In an effort to analyze the role that genes within the BoLA complex may play in host resistance to ticks, we have evaluated components of this system within a herd of cattle established at our laboratory that has been phenotyped for ectoparasite susceptibility. Of three microsatellite loci within the BoLA complex analyzed, alleles of two microsatellite loci within the BoLA class IIa cluster (DRB1-118 and DRB3-174) associated with the tick-resistant phenotype, prompting further investigation of gene sequences within the DRB3 region. DRB3 is a class IIa gene, the second exon of which is highly polymorphic since it encodes the antigen recognition site of the DR class II molecule. Analysis of the second exon of the DRB3 gene from the phenotyped calves in our herd revealed a significant association between the DRB3*4401 allele and the tick-resistant phenotype. To our knowledge, this is the first report of a putative association between a class IIa DRB3 sequence and host resistance to the Lone Star tick. Elucidation of the mechanism involved in tick resistance will contribute to improving breeding schemes for parasite resistance, which will be beneficial to the cattle industry.

  19. Class Schedules Need Class.

    ERIC Educational Resources Information Center

    Monfette, Ronald J.

    1986-01-01

    Argues that college publications, including class schedules, must be accurate, timely, and easy to read and follow. Describes Schoolcraft College's unified format approach to publications marketing. Offers suggestions on the design, format, and distribution of class schedules. (DMM)

  20. Immune complexes (IC) down-regulate the basal and interferon-γ-induced expression of MHC Class II on human monocytes

    PubMed Central

    Barrionuevo, P; Beigier-Bompadre, M; De La Barrera, S; Alves-Rosa, M F; Fernandez, G; Palermo, M S; Isturiz, M A

    2001-01-01

    The interaction of Fc receptors for IgG (FcγRs) on monocytes/macrophages with immune complexes (IC) triggers regulatory and effector functions. Previous studies have shown that FcγR–IC interactions inhibit the IFN-γ-induced expression of MHC class II in murine macrophages. However, the mechanism(s) responsible for these effects have not been elucidated. In addition, whether this IC-dependent effect also occurs in human cells is not known. Taking into account the fact that IC and IFN-γ are frequently found in infections and autoimmune disorders, together with the crucial role MHC class II molecules play in the regulation of immune response, we explored the effect and mechanism of IC-induced MHC class II down-regulation in human peripheral blood mononuclear cells (PBMC). This effect was studied either in the presence or absence of IFN-γ. We demonstrate that IC exert a drastic inhibition of basal and IFN-γ-induced expression of MHC class II on human monocytes. This effect was mediated through the interaction of IC with both FcγRI and FcγRII. Moreover, similar results were obtained using supernatants from IC-treated PBMC. The IC-induced down-regulation of MHC class II is abrogated by pepstatin and phosphoramidon, supporting the role of aspartic protease(s) and metalloprotease(s) in this process. In parallel with MHC class II expression, antigen presentation was markedly inhibited in the presence of IC. PMID:11529917

  1. 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.

  2. HIV Controllers Exhibit Enhanced Frequencies of Major Histocompatibility Complex Class II Tetramer+ Gag-Specific CD4+ T Cells in Chronic Clade C HIV-1 Infection

    PubMed Central

    Laher, Faatima; Ranasinghe, Srinika; Porichis, Filippos; Mewalal, Nikoshia; Pretorius, Karyn; Ismail, Nasreen; Buus, Søren; Stryhn, Anette; Carrington, Mary; Walker, Bruce D.; Ndung'u, Thumbi

    2017-01-01

    ABSTRACT Immune control of viral infections is heavily dependent on helper CD4+ T cell function. However, the understanding of the contribution of HIV-specific CD4+ T cell responses to immune protection against HIV-1, particularly in clade C infection, remains incomplete. Recently, major histocompatibility complex (MHC) class II tetramers have emerged as a powerful tool for interrogating antigen-specific CD4+ T cells without relying on effector functions. Here, we defined the MHC class II alleles for immunodominant Gag CD4+ T cell epitopes in clade C virus infection, constructed MHC class II tetramers, and then used these to define the magnitude, function, and relation to the viral load of HIV-specific CD4+ T cell responses in a cohort of untreated HIV clade C-infected persons. We observed significantly higher frequencies of MHC class II tetramer-positive CD4+ T cells in HIV controllers than progressors (P = 0.0001), and these expanded Gag-specific CD4+ T cells in HIV controllers showed higher levels of expression of the cytolytic proteins granzymes A and B. Importantly, targeting of the immunodominant Gag41 peptide in the context of HLA class II DRB1*1101 was associated with HIV control (r = −0.5, P = 0.02). These data identify an association between HIV-specific CD4+ T cell targeting of immunodominant Gag epitopes and immune control, particularly the contribution of a single class II MHC-peptide complex to the immune response against HIV-1 infection. Furthermore, these results highlight the advantage of the use of class II tetramers in evaluating HIV-specific CD4+ T cell responses in natural infections. IMPORTANCE Increasing evidence suggests that virus-specific CD4+ T cells contribute to the immune-mediated control of clade B HIV-1 infection, yet there remains a relative paucity of data regarding the role of HIV-specific CD4+ T cells in shaping adaptive immune responses in individuals infected with clade C, which is responsible for the majority of HIV

  3. HIV Controllers Exhibit Enhanced Frequencies of Major Histocompatibility Complex Class II Tetramer(+) Gag-Specific CD4(+) T Cells in Chronic Clade C HIV-1 Infection.

    PubMed

    Laher, Faatima; Ranasinghe, Srinika; Porichis, Filippos; Mewalal, Nikoshia; Pretorius, Karyn; Ismail, Nasreen; Buus, Søren; Stryhn, Anette; Carrington, Mary; Walker, Bruce D; Ndung'u, Thumbi; Ndhlovu, Zaza M

    2017-04-01

    Immune control of viral infections is heavily dependent on helper CD4(+) T cell function. However, the understanding of the contribution of HIV-specific CD4(+) T cell responses to immune protection against HIV-1, particularly in clade C infection, remains incomplete. Recently, major histocompatibility complex (MHC) class II tetramers have emerged as a powerful tool for interrogating antigen-specific CD4(+) T cells without relying on effector functions. Here, we defined the MHC class II alleles for immunodominant Gag CD4(+) T cell epitopes in clade C virus infection, constructed MHC class II tetramers, and then used these to define the magnitude, function, and relation to the viral load of HIV-specific CD4(+) T cell responses in a cohort of untreated HIV clade C-infected persons. We observed significantly higher frequencies of MHC class II tetramer-positive CD4(+) T cells in HIV controllers than progressors (P = 0.0001), and these expanded Gag-specific CD4(+) T cells in HIV controllers showed higher levels of expression of the cytolytic proteins granzymes A and B. Importantly, targeting of the immunodominant Gag41 peptide in the context of HLA class II DRB1*1101 was associated with HIV control (r = -0.5, P = 0.02). These data identify an association between HIV-specific CD4(+) T cell targeting of immunodominant Gag epitopes and immune control, particularly the contribution of a single class II MHC-peptide complex to the immune response against HIV-1 infection. Furthermore, these results highlight the advantage of the use of class II tetramers in evaluating HIV-specific CD4(+) T cell responses in natural infections.IMPORTANCE Increasing evidence suggests that virus-specific CD4(+) T cells contribute to the immune-mediated control of clade B HIV-1 infection, yet there remains a relative paucity of data regarding the role of HIV-specific CD4(+) T cells in shaping adaptive immune responses in individuals infected with clade C, which is responsible for the majority of

  4. Genomic structure of the horse major histocompatibility complex class II region resolved using PacBio long-read sequencing technology

    PubMed Central

    Viļuma, Agnese; Mikko, Sofia; Hahn, Daniela; Skow, Loren; Andersson, Göran; Bergström, Tomas F.

    2017-01-01

    The mammalian Major Histocompatibility Complex (MHC) region contains several gene families characterized by highly polymorphic loci with extensive nucleotide diversity, copy number variation of paralogous genes, and long repetitive sequences. This structural complexity has made it difficult to construct a reliable reference sequence of the horse MHC region. In this study, we used long-read single molecule, real-time (SMRT) sequencing technology from Pacific Biosciences (PacBio) to sequence eight Bacterial Artificial Chromosome (BAC) clones spanning the horse MHC class II region. The final assembly resulted in a 1,165,328 bp continuous gap free sequence with 35 manually curated genomic loci of which 23 were considered to be functional and 12 to be pseudogenes. In comparison to the MHC class II region in other mammals, the corresponding region in horse shows extraordinary copy number variation and different relative location and directionality of the Eqca-DRB, -DQA, -DQB and –DOB loci. This is the first long-read sequence assembly of the horse MHC class II region with rigorous manual gene annotation, and it will serve as an important resource for association studies of immune-mediated equine diseases and for evolutionary analysis of genetic diversity in this region. PMID:28361880

  5. Genomic structure of the horse major histocompatibility complex class II region resolved using PacBio long-read sequencing technology.

    PubMed

    Viļuma, Agnese; Mikko, Sofia; Hahn, Daniela; Skow, Loren; Andersson, Göran; Bergström, Tomas F

    2017-03-31

    The mammalian Major Histocompatibility Complex (MHC) region contains several gene families characterized by highly polymorphic loci with extensive nucleotide diversity, copy number variation of paralogous genes, and long repetitive sequences. This structural complexity has made it difficult to construct a reliable reference sequence of the horse MHC region. In this study, we used long-read single molecule, real-time (SMRT) sequencing technology from Pacific Biosciences (PacBio) to sequence eight Bacterial Artificial Chromosome (BAC) clones spanning the horse MHC class II region. The final assembly resulted in a 1,165,328 bp continuous gap free sequence with 35 manually curated genomic loci of which 23 were considered to be functional and 12 to be pseudogenes. In comparison to the MHC class II region in other mammals, the corresponding region in horse shows extraordinary copy number variation and different relative location and directionality of the Eqca-DRB, -DQA, -DQB and -DOB loci. This is the first long-read sequence assembly of the horse MHC class II region with rigorous manual gene annotation, and it will serve as an important resource for association studies of immune-mediated equine diseases and for evolutionary analysis of genetic diversity in this region.

  6. Isolation of chicken major histocompatibility complex class II (B-L) beta chain sequences: comparison with mammalian beta chains and expression in lymphoid organs.

    PubMed Central

    Bourlet, Y; Béhar, G; Guillemot, F; Fréchin, N; Billault, A; Chaussé, A M; Zoorob, R; Auffray, C

    1988-01-01

    By cross-hybridization in low stringency conditions, using a probe derived from an HLA-DQ beta cDNA clone, we have isolated several chicken genomic DNA clones. These clones were mapped to the major histocompatibility complex (MHC) of the chick (B complex) by virtue of their ability to detect restriction enzyme length polymorphisms between congenic lines of chicken. Evidence was obtained for the presence of at least three B-L beta genes in the chicken genome. The B-L beta genes are transcribed specifically in tissues containing cells of the B lymphocyte and myeloid lineages and expressing the B-L antigens. Exons encoding the beta 1, beta 2 and transmembrane domains of a B-L beta chain have been identified with 63, 66 and 62% similarity with the HLA-DQ beta sequence. This first isolation of an MHC class II gene outside of the mammalian class provides insight into the evolution of MHC genes based on the comparison of avian and mammalian class II beta chain amino acid and nucleotide sequences. Images PMID:2841107

  7. 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

  8. Evolution of the major histocompatibility complex: Isolation of class II beta cDNAs from two monotremes, the platypus and the short-beaked echidna.

    PubMed

    Belov, Katherine; Lam, Mary K P; Hellman, Lars; Colgan, Donald J

    2003-09-01

    Extant mammals are composed of three lineages: the eutherians, the marsupials and the monotremes. The majority of the mammalian major histocompatibility complex (MHC) data is based on the eutherian mammals, which generally have three classical MHC class II beta chain gene clusters - DRB, DQB and DPB, as well as the non-classical DMB and DOB. Marsupial DMB, DAB and DBB have been characterised. Confusion still surrounds the relationship of the marsupial DAB and DBB genes with the classical eutherian class II clusters. Here we present the first monotreme MHC class II beta chain sequences. Four MHC class II beta chain sequences were isolated from a spleen cDNA library from the short-beaked echidna, and one from a spleen cDNA library from platypus using a brushtail possum DAB probe. Given the non-orthologous relationship of the monotreme sequences with marsupial and eutherian beta chain clusters, we recommend that the five new monotreme sequences be assigned the nomenclature 'DZB', signifying the description of a new mammalian beta chain cluster. Our analysis suggests that all mammalian beta chain sequences (except DMB) evolved from a common ancestor. Maximum likelihood analysis places the monotreme beta chain sequences at the base of the mammalian clade, indicating their ancestral status. However, within the mammalian clade, monophyletic clades are not robust, and elucidation of the order of gene duplication that gave rise to the present-day gene clusters is not yet possible.

  9. Ru, Os, Rh mixed-metal complexes are a potential novel class of oxygen independent photosensitizers for photodynamic therapy (PDT)

    NASA Astrophysics Data System (ADS)

    Storrie, Brian; Holder, Alvin; Brewer, Karen J.

    2006-02-01

    Mixed-metal supramolecular complexes coupling Ru and Os light absorber units to a central, reactive Rh site have been designed of the type [{(bpy)2M(dpp)}2RhCl2]5+. These complexes possess intense metal-to-ligand charge transfer transitions when excited at 500-700 nm making them good light absorbers. The presence of the Rh site introduces low lying metal-to-metal charge transfer states that are capable of visible light induced photocleavage of DNA via an oxygen independent pathway.1 We report here a study of the photodynamic action of supramolecular mixed-metal complexes showing that these systems inhibit cell replication after exposure to light while displaying no impact on cell replication in the dark. This photodynamic action has been studied using cultured Vero cells with a pre-incubation with the complexes, rinsing to remove complex from the media, followed by photo-activation and cell growth assay. The photodynamic action of this new series of complexes can be tuned as a function of components of the supramolecular assembly and complexes capable of coupling to targeting proteins and fluorescent reporter groups have been synthesized.

  10. 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.

  11. Proteasome-independent major histocompatibility complex class I cross-presentation mediated by papaya mosaic virus-like particles leads to expansion of specific human T cells.

    PubMed

    Leclerc, Denis; Beauseigle, Diane; Denis, Jérome; Morin, Hélène; Paré, Christine; Lamarre, Alain; Lapointe, Réjean

    2007-02-01

    The development of versatile vaccine platforms is a priority that is recognized by health authorities worldwide; such platforms should induce both arms of the immune system, the humoral and cytotoxic-T-lymphocyte responses. In this study, we have established that a vaccine platform based on the coat protein of papaya mosaic virus (PapMV CP), previously shown to induce a humoral response, can induce major histocompatibility complex (MHC) class I cross-presentation of HLA-A*0201 epitopes from gp100, a melanoma antigen, and from influenza virus M1 matrix protein. PapMV proteins were able to assemble into stable virus-like particles (VLPs) in a crystalline and repetitive structure. When we pulsed HLA-A*0201+ antigen-presenting cells (APCs) with the recombinant PapMV FLU or gp100, we noted that antigen-specific CD8+ T cells were highly reactive to these APCs, demonstrating that the epitope from the VLPs were processed and loaded on the MHC class I complex. APCs were preincubated with two different proteasome inhibitors, which did not affect the efficiency of peptide presentation on MHC class I. Classical presentation from an endogenous antigen was abolished in the same conditions. Clearly, antigen presentation mediated by the PapMV system was proteasome independent. Finally, PapMV-pulsed APCs had the capacity to expand highly avid antigen-specific T cells against the influenza virus M1 HLA-A*0201 epitope when cocultured with autologous peripheral blood mononuclear cells. This study demonstrates the potential of PapMV for MHC class I cross-presentation and for the expansion of human antigen-specific T cells. It makes VLPs from PapMV CP a very attractive platform to trigger cellular responses for vaccine development against chronic infectious diseases and cancers.

  12. Multi-target drugs to address multiple checkpoints in complex inflammatory pathologies: evolutionary cues for novel "first-in-class" anti-inflammatory drug candidates: a reviewer's perspective.

    PubMed

    Mathew, Geetha; Unnikrishnan, M K

    2015-10-01

    Inflammation is a complex, metabolically expensive process involving multiple signaling pathways and regulatory mechanisms which have evolved over evolutionary timescale. Addressing multiple targets of inflammation holistically, in moderation, is probably a more evolutionarily viable strategy, as compared to current therapy which addresses drug targets in isolation. Polypharmacology, addressing multiple targets, is commonly used in complex ailments, suggesting the superior safety and efficacy profile of multi-target (MT) drugs. Phenotypic drug discovery, which generated successful MT and first-in-class drugs in the past, is now re-emerging. A multi-pronged approach, which modulates the evolutionarily conserved, robust and pervasive cellular mechanisms of tissue repair, with AMPK at the helm, regulating the complex metabolic/immune/redox pathways underlying inflammation, is perhaps a more viable strategy than addressing single targets in isolation. Molecules that modulate multiple molecular mechanisms of inflammation in moderation (modulating TH cells toward the anti-inflammatory phenotype, activating AMPK, stimulating Nrf2 and inhibiting NFκB) might serve as a model for a novel Darwinian "first-in-class" therapeutic category that holistically addresses immune, redox and metabolic processes associated with inflammatory repair. Such a multimodal biological activity is supported by the fact that several non-calorific pleiotropic natural products with anti-inflammatory action have been incorporated into diet (chiefly guided by the adaptive development of olfacto-gustatory preferences over evolutionary timescales) rendering such molecules, endowed with evolutionarily privileged molecular scaffolds, naturally oriented toward multiple targets.

  13. Meiotic DNA double-strand break repair requires two nucleases, MRN and Ctp1, to produce a single size class of Rec12 (Spo11)-oligonucleotide complexes.

    PubMed

    Milman, Neta; Higuchi, Emily; Smith, Gerald R

    2009-11-01

    Programmed DNA double-strand breaks (DSBs) in meiosis are formed by Spo11 (Rec12 in fission yeast), a topoisomerase II-like protein, which becomes covalently attached to DNA 5' ends. For DSB repair through homologous recombination, the protein must be removed from these DNA ends. We show here that Rec12 is endonucleolytically removed from DSB ends attached to a short oligonucleotide (Rec12-oligonucleotide complex), as is Spo11 in budding yeast. Fission yeast, however, has only one size class of Rec12-oligonucleotide complexes, whereas budding yeast has two size classes, suggesting different endonucleolytic regulatory mechanisms. Rec12-oligonucleotide generation strictly requires Ctp1 (Sae2 nuclease homolog), the Rad32 (Mre11) nuclease domain, and Rad50 of the MRN complex. Surprisingly, Nbs1 is not strictly required, indicating separable roles for the MRN subunits. On the basis of these and other data, we propose that Rad32 nuclease has the catalytic site for Rec12-oligonucleotide generation and is activated by Ctp1, which plays an additional role in meiotic recombination.

  14. Alternative endogenous protein processing via an autophagy-dependent pathway compensates for Yersinia-mediated inhibition of endosomal major histocompatibility complex class II antigen presentation.

    PubMed

    Rüssmann, Holger; Panthel, Klaus; Köhn, Brigitte; Jellbauer, Stefan; Winter, Sebastian E; Garbom, Sara; Wolf-Watz, Hans; Hoffmann, Sigrid; Grauling-Halama, Silke; Geginat, Gernot

    2010-12-01

    Extracellular Yersinia pseudotuberculosis employs a type III secretion system (T3SS) for translocating virulence factors (Yersinia outer proteins [Yops]) directly into the cytosol of eukaryotic cells. Recently, we used YopE as a carrier molecule for T3SS-dependent secretion and translocation of listeriolysin O (LLO) from Listeria monocytogenes. We demonstrated that translocation of chimeric YopE/LLO into the cytosol of macrophages by Yersinia results in the induction of a codominant antigen-specific CD4 and CD8 T-cell response in orally immunized mice. In this study, we addressed the requirements for processing and major histocompatibility complex (MHC) class II presentation of chimeric YopE proteins translocated into the cytosol of macrophages by the Yersinia T3SS. Our data demonstrate the ability of Yersinia to counteract exogenous MHC class II antigen presentation of secreted hybrid YopE by the action of wild-type YopE and YopH. In the absence of exogenous MHC class II antigen presentation, an alternative pathway was identified for YopE fusion proteins originating in the cytosol. This endogenous antigen-processing pathway was sensitive to inhibitors of phagolysosomal acidification and macroautophagy, but it did not require the function either of the proteasome or of transporters associated with antigen processing. Thus, by an autophagy-dependent mechanism, macrophages are able to compensate for the YopE/YopH-mediated inhibition of the endosomal MHC class II antigen presentation pathway for exogenous antigens. This is the first report demonstrating that autophagy might enable the host to mount an MHC class II-restricted CD4 T-cell response against translocated bacterial virulence factors. We provide critical new insights into the interaction between the mammalian immune system and a human pathogen.

  15. Antibodies to major histocompatibility complex class II antigens directly prime neutrophils and cause acute lung injury in a two-event in vivo rat model.

    PubMed

    Kelher, Marguerite R; Banerjee, Anirban; Gamboni, Fabia; Anderson, Cameron; Silliman, Christopher C

    2016-12-01

    Transfusion-related acute lung injury (TRALI) is a significant cause of mortality, especially after transfusions containing antibodies to major histocompatibility complex (MHC) class II antigens. We hypothesize that a first event induces both 1) polymorphonuclear neutrophils (PMNs) to express MHC class II antigens, and 2) activation of the pulmonary endothelium, leading to PMN sequestration, so that the infusion of specific MHC class II antibodies to these antigens causes PMN-mediated acute lung injury (ALI). Rats were treated with saline (NS), endotoxin (lipopolysaccharide [LPS]), or cytokines (interferon-γ [IFNγ], macrophage colony-stimulating factor [MCSF], tumor necrosis factor-α [TNFα]); the PMNs were isolated; and the surface expression of the MHC class II antigen OX6 and priming by OX6 antibodies were measured by flow cytometry or priming assays. A two-event model of ALI was completed with NS, LPS, or IFNγ/MCSF/TNFα (first events) and the infusion of OX6 (second event). Compared with NS incubation, rats treated with either LPS or IFNγ/MCSF/TNFα exhibited OX6 PMN surface expression, OX6 antibodies primed the formyl-methionyl-leucyl phenylalanine (fMLF)-activated respiratory burst, and PMN sequestration was increased. OX6 antibody infusion into LPS-incubated or IFNγ/MCSF/TNFα-incubated rats elicited ALI, the OX6 antibody was present on the PMNs, and PMN depletion abrogated ALI. Proinflammatory first events induce PMN MHC class II surface expression, activation of the pulmonary endothelium, and PMN sequestration such that the infusion of cognate antibodies precipitates TRALI. © 2016 AABB.

  16. 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.

  17. 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. © 2016 Starnes et al.; Published by Cold Spring Harbor Laboratory Press.

  18. 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

  19. Giant Panda Genomic Data Provide Insight into the Birth-and-Death Process of Mammalian Major Histocompatibility Complex Class II Genes

    PubMed Central

    Wan, Qiu-Hong; Zeng, Chang-Jun; Ni, Xiao-Wei; Pan, Hui-Juan; Fang, Sheng-Guo

    2009-01-01

    To gain an understanding of the genomic structure and evolutionary history of the giant panda major histocompatibility complex (MHC) genes, we determined a 636,503-bp nucleotide sequence spanning the MHC class II region. Analysis revealed that the MHC class II region from this rare species contained 26 loci (17 predicted to be expressed), of which 10 are classical class II genes (1 DRA, 2 DRB, 2 DQA, 3 DQB, 1 DYB, 1 DPA, and 2 DPB) and 4 are non-classical class II genes (1 DOA, 1 DOB, 1 DMA, and 1 DMB). The presence of DYB, a gene specific to ruminants, prompted a comparison of the giant panda class II sequence with those of humans, cats, dogs, cattle, pigs, and mice. The results indicated that birth and death events within the DQ and DRB-DY regions led to major lineage differences, with absence of these regions in the cat and in humans and mice respectively. The phylogenetic trees constructed using all expressed alpha and beta genes from marsupials and placental mammals showed that: (1) because marsupials carry loci corresponding to DR, DP, DO and DM genes, those subregions most likely developed before the divergence of marsupials and placental mammals, approximately 150 million years ago (MYA); (2) conversely, the DQ and DY regions must have evolved later, but before the radiation of placental mammals (100 MYA). As a result, the typical genomic structure of MHC class II genes for the giant panda is similar to that of the other placental mammals and corresponds to BTNL2∼DR1∼DQ∼DR2∼DY∼DO_box∼DP∼COL11A2. Over the past 100 million years, there has been birth and death of mammalian DR, DQ, DY, and DP genes, an evolutionary process that has brought about the current species-specific genomic structure of the MHC class II region. Furthermore, facing certain similar pathogens, mammals have adopted intra-subregion (DR and DQ) and inter-subregion (between DQ and DP) convergent evolutionary strategies for their alpha and beta genes, respectively. PMID:19127303

  20. Class II major histocompatibility complex mutant mice to study the germ-line bias of T-cell antigen receptors

    PubMed Central

    Silberman, Daniel; Krovi, Sai Harsha; Tuttle, Kathryn D.; Crooks, James; Reisdorph, Richard; White, Janice; Gross, James; Matsuda, Jennifer L.; Gapin, Laurent; Marrack, Philippa; Kappler, John W.

    2016-01-01

    The interaction of αβ T-cell antigen receptors (TCRs) with peptides bound to MHC molecules lies at the center of adaptive immunity. Whether TCRs have evolved to react with MHC or, instead, processes in the thymus involving coreceptors and other molecules select MHC-specific TCRs de novo from a random repertoire is a longstanding immunological question. Here, using nuclease-targeted mutagenesis, we address this question in vivo by generating three independent lines of knockin mice with single-amino acid mutations of conserved class II MHC amino acids that often are involved in interactions with the germ-line–encoded portions of TCRs. Although the TCR repertoire generated in these mutants is similar in size and diversity to that in WT mice, the evolutionary bias of TCRs for MHC is suggested by a shift and preferential use of some TCR subfamilies over others in mice expressing the mutant class II MHCs. Furthermore, T cells educated on these mutant MHC molecules are alloreactive to each other and to WT cells, and vice versa, suggesting strong functional differences among these repertoires. Taken together, these results highlight both the flexibility of thymic selection and the evolutionary bias of TCRs for MHC. PMID:27588903

  1. Class II major histocompatibility complex mutant mice to study the germ-line bias of T-cell antigen receptors.

    PubMed

    Silberman, Daniel; Krovi, Sai Harsha; Tuttle, Kathryn D; Crooks, James; Reisdorph, Richard; White, Janice; Gross, James; Matsuda, Jennifer L; Gapin, Laurent; Marrack, Philippa; Kappler, John W

    2016-09-20

    The interaction of αβ T-cell antigen receptors (TCRs) with peptides bound to MHC molecules lies at the center of adaptive immunity. Whether TCRs have evolved to react with MHC or, instead, processes in the thymus involving coreceptors and other molecules select MHC-specific TCRs de novo from a random repertoire is a longstanding immunological question. Here, using nuclease-targeted mutagenesis, we address this question in vivo by generating three independent lines of knockin mice with single-amino acid mutations of conserved class II MHC amino acids that often are involved in interactions with the germ-line-encoded portions of TCRs. Although the TCR repertoire generated in these mutants is similar in size and diversity to that in WT mice, the evolutionary bias of TCRs for MHC is suggested by a shift and preferential use of some TCR subfamilies over others in mice expressing the mutant class II MHCs. Furthermore, T cells educated on these mutant MHC molecules are alloreactive to each other and to WT cells, and vice versa, suggesting strong functional differences among these repertoires. Taken together, these results highlight both the flexibility of thymic selection and the evolutionary bias of TCRs for MHC.

  2. Complexity.

    PubMed

    Gómez-Hernández, J Jaime

    2006-01-01

    It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.

  3. Medication beliefs, treatment complexity, and non-adherence to different drug classes in patients with type 2 diabetes.

    PubMed

    de Vries, Sieta T; Keers, Joost C; Visser, Rosalie; de Zeeuw, Dick; Haaijer-Ruskamp, Flora M; Voorham, Jaco; Denig, Petra

    2014-02-01

    To assess the relationship of patients' medication beliefs and treatment complexity with unintentional and intentional non-adherence for three therapeutic groups commonly used by patients with type 2 diabetes. Survey data about adherence (Medication Adherence Report Scale) and beliefs about medicines (Beliefs about Medicines Questionnaire) were combined with prescription data from the Groningen Initiative to ANalyse Type 2 diabetes Treatment (GIANTT) database. Patients were classified as being adherent, mainly unintentional non-adherent, or partly intentional non-adherent per therapeutic group (glucose-, blood pressure-, and lipid-lowering drugs). Treatment complexity was measured using the Medication Regimen Complexity Index, which includes the dosage form, dosing frequency and additional directions of taking the drug. Analyses were performed using Kruskal-Wallis and Mann-Whitney U-tests. Of 257 contacted patients, 133 (52%) returned the questionnaire. The patients had a mean age of 66years and 50% were females. Necessity beliefs were not significantly different between the adherers, mainly unintentional non-adherers, and partly intentional non-adherers (differences smaller than 5 points on a scale from 5 to 25). For blood pressure-lowering drugs, patients reporting intentional non-adherence had higher concern beliefs than adherers (8 point difference, P=0.01). Treatment complexity scores were lower for adherers but similar for mainly unintentional and partly intentional non-adherers to glucose- and blood pressure-lowering drugs. Treatment complexity was related to non-adherence in general. Beliefs about necessity were not strongly associated with non-adherence, while patients' concern beliefs may be associated with intentional non-adherence. However, the role of these determinants differs per therapeutic group. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. 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. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Transloading of tumor cells with foreign major histocompatibility complex class I peptide ligand: a novel general strategy for the generation of potent cancer vaccines.

    PubMed Central

    Schmidt, W; Steinlein, P; Buschle, M; Schweighoffer, T; Herbst, E; Mechtler, K; Kirlappos, H; Birnstiel, M L

    1996-01-01

    The major hurdle to be cleared in active immunotherapy of cancer is the poor immunogenicity of cancer cells. In previous attempts to overcome this problem, whole tumor cells have been used as vaccines, either admixed with adjuvant(s) or genetically engineered to express nonself proteins or immunomodulatory factors before application. We have developed a novel approach to generate an immunogeneic, highly effective vaccine: major histocompatibility complex (MHC) class I-positive cancer cells are administered together with MHC class I-matched peptide ligands of foreign, nonself origin, generated by a procedure we term transloading. Murine tumor lines of the H2-Kd or the H2-Db haplotype, melanoma M-3 and B16-F10, respectively, as well as colon carcinoma CT-26 (H2-Kd), were transloaded with MHC-matched influenza virus-derived peptides and applied as irradiated vaccines. Mice bearing a deposit of live M-3 melanoma cells were efficiently cured by this treatment. In the CT-26 colon carcinoma and the B16-F10 melanoma, high efficacies were obtained against tumor challenge, suggesting the universal applicability of this new type of vaccine. With foreign peptide ligands adapted to the requirements of a desired MHC class I haplotype, this concept may be used for the treatment of human cancers. Images Fig. 1 PMID:8790404

  6. Class-paired Fuzzy SubNETs: A paired variant of the rank-based network analysis family for feature selection based on protein complexes.

    PubMed

    Goh, Wilson Wen Bin; Wong, Limsoon

    2017-04-08

    Identifying reproducible yet relevant protein features in proteomics data is a major challenge. Analysis at the level of protein complexes can resolve this issue and we have developed a suite of feature-selection methods collectively referred to as Rank-Based Network Analysis (RBNA). RBNAs differ in their individual statistical test setup but are similar in the sense that they deploy rank-defined weights amongst proteins per sample. This procedure is known as gene fuzzy scoring. Currently, no RBNA exists for paired-sample scenarios where both control and test tissues originate from the same source (e.g. same patient). It is expected that paired tests, when used appropriately, are more powerful than approaches intended for unpaired samples. We report that the class-paired RBNA, PPFSNET, dominates in both simulated and real data scenarios. Moreover, for the first time, we explicitly incorporate batch-effect resistance as an additional evaluation criterion for feature-selection approaches. Batch effects are class irrelevant variations arising from different handlers or processing times, and can obfuscate analysis. We demonstrate that PPFSNET and PFSNET, are particularly resistant against batch effects, and only select features strongly correlated with class but not batch. This article is protected by copyright. All rights reserved.

  7. Education and Class.

    ERIC Educational Resources Information Center

    Van Galen, Jane A.

    2000-01-01

    The working class is nearly invisible in multicultural education literature. Examines the possibilities of a more careful foregrounding of the complexities of social class in shaping life chances, focusing on the educational experiences of working class students and discussing the poor in order to promote understanding of the potential of teacher…

  8. 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.

  9. 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

  10. Crystallographic and Computational Studies of a Class II MHC Complex with a Nonconforming Peptide: HLA-DRA/DRB3*0101

    NASA Astrophysics Data System (ADS)

    Parry, Christian S.; Gorski, Jack; Stern, Lawrence J.

    2003-03-01

    The stable binding of processed foreign peptide to a class II major histocompatibility (MHC) molecule and subsequent presentation to a T cell receptor is a central event in immune recognition and regulation. Polymorphic residues on the floor of the peptide binding site form pockets that anchor peptide side chains. These and other residues in the helical wall of the groove determine the specificity of each allele and define a motif. Allele specific motifs allow the prediction of epitopes from the sequence of pathogens. There are, however, known epitopes that do not satisfy these motifs: anchor motifs are not adequate for predicting epitopes as there are apparently major and minor motifs. We present crystallographic studies into the nature of the interactions that govern the binding of these so called nonconforming peptides. We would like to understand the role of the P10 pocket and find out whether the peptides that do not obey the consensus anchor motif bind in the canonical conformation observed in in prior structures of class II MHC-peptide complexes. HLA-DRB3*0101 complexed with peptide crystallized in unit cell 92.10 x 92.10 x 248.30 (90, 90, 90), P41212, and the diffraction data is reliable to 2.2ÅWe are complementing our studies with dynamical long time simulations to answer these questions, particularly the interplay of the anchor motifs in peptide binding, the range of protein and ligand conformations, and water hydration structures.

  11. Lack of Major Histocompatibility Complex Class I Upregulation and Restrictive Infection by JC Virus Hamper Detection of Neurons by T Lymphocytes in the Central Nervous System.

    PubMed

    Wüthrich, Christian; Batson, Stephanie; Koralnik, Igor J

    2015-08-01

    The human polyomavirus JC (JCV) infects glial cells in immunosuppressed individuals, leading to progressive multifocal leukoencephalopathy. Polyomavirus JC can also infect neurons in patients with JCV granule cell neuronopathy and JCV encephalopathy. CD8-positive T cells play a crucial role in viral containment and outcome in progressive multifocal leukoencephalopathy, but whether CD8-positive T cells can also recognize JCV-infected neurons is unclear. We used immunohistochemistry to determine the prevalence of T cells in neuron-rich areas of archival brain samples from 77 patients with JCV CNS infections and 94 control subjects. Neurons predominantly sustained a restrictive infection with expression of JCV regulatory protein T antigen (T Ag), whereas glial cells were productively infected and expressed both T Ag and the capsid protein VP1. T cells were more prevalent near JCV-infected cells with intact nuclei expressing both T Ag and VP1 compared with those expressing either protein alone. CD8-positive T cells also colocalized more with JCV-infected glial cells than with JCV-infected neurons. Major histocompatibility complex class I expression was upregulated in JCV-infected areas but could only be detected in rare neurons interspersed with infected glial cells. These results suggest that isolated neurons harboring restrictive JCV infection do not upregulate major histocompatibility complex class I and thus may escape recognition by CD8-positive T cells.

  12. The SUFBC2 D complex is required for the biogenesis of all major classes of plastid Fe-S proteins.

    PubMed

    Hu, Xueyun; Kato, Yukako; Sumida, Akihiro; Tanaka, Ayumi; Tanaka, Ryouichi

    2017-04-01

    Iron-sulfur (Fe-S) proteins play crucial roles in plastids, participating in photosynthesis and other metabolic pathways. Fe-S clusters are thought to be assembled on a scaffold complex composed of SUFB, SUFC and SUFD proteins. However, several additional proteins provide putative scaffold functions in plastids, and, therefore, the contribution of SUFB, C and D proteins to overall Fe-S assembly still remains unclear. In order to gain insights regarding Fe-S cluster biosynthesis in plastids, we analyzed the complex composed of SUFB, C and D in Arabidopsis by blue native-polyacrylamide gel electrophoresis. Using this approach, a major complex of 170 kDa containing all subunits was detected, indicating that these proteins constitute a SUFBC2 D complex similar to their well characterized bacterial counterparts. The functional effects of SUFB, SUFC or SUFD depletion were analyzed using an inducible RNAi silencing system to specifically target the aforementioned components; resulting in a decrease of various plastidic Fe-S proteins including the PsaA/B and PsaC subunits of photosystem I, ferredoxin and glutamine oxoglutarate aminotransferase. In contrast, the knockout of potential Fe-S scaffold proteins, NFU2 and HCF101, resulted in a specific decrease in the PsaA/B and PsaC levels. These results indicate that the functions of SUFB, SUFC and SUFD for Fe-S cluster biosynthesis cannot be replaced by other scaffold proteins and that SUFBC2 D, NFU2 and HCF101 are involved in the same pathway for the biogenesis of PSI. Taken together, our results provide in vivo evidence supporting the hypothesis that SUFBC2 D is the major, and possibly sole scaffold in plastids. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  13. Structure of the acetophenone carboxylase core complex: prototype of a new class of ATP-dependent carboxylases/hydrolases

    PubMed Central

    Weidenweber, Sina; Schühle, Karola; Demmer, Ulrike; Warkentin, Eberhard; Ermler, Ulrich; Heider, Johann

    2017-01-01

    Degradation of the aromatic ketone acetophenone is initiated by its carboxylation to benzoylacetate catalyzed by acetophenone carboxylase (Apc) in a reaction dependent on the hydrolysis of two ATP to ADP and Pi. Apc is a large protein complex which dissociates during purification into a heterooctameric Apc(αα′βγ)2 core complex of 482 kDa and Apcε of 34 kDa. In this report, we present the X-ray structure of the Apc(αα′βγ)2 core complex from Aromatoleum aromaticum at ca. 3 Å resolution which reveals a unique modular architecture and serves as model of a new enzyme family. Apcβ contains a novel domain fold composed of two β-sheets in a barrel-like arrangement running into a bundle of eight short polyproline (type II)-like helical segments. Apcα and Apcα′ possess ATP binding modules of the ASKHA superfamily integrated into their multidomain structures and presumably operate as ATP-dependent kinases for acetophenone and bicarbonate, respectively. Mechanistic aspects of the novel carboxylation reaction requiring massive structural rearrangements are discussed and criteria for specifically annotating the family members Apc, acetone carboxylase and hydantoinase are defined. PMID:28054554

  14. Membrane Ia expression and antigen-presenting accessory cell function of L cells transfected with class II major histocompatibility complex genes

    PubMed Central

    1984-01-01

    To study the relationship between the structure and function of Ia antigens, as well as the physiologic requirements for antigen presentation to major histocompatibility complex-restricted T cells, class II A alpha and A beta genes from the k and d haplotypes were transfected into Ltk- fibroblasts using the calcium phosphate coprecipitation technique. Individually transfected genes were actively transcribed in the L cells without covalent linkage to, or cotransformation with, viral enhancer sequences. However, cell surface expression of detectable I-A required the presence of transfected A alpha dA beta d or A alpha kA beta k pairs in a single cell. The level of I-A expression under these conditions was 1/5-1/10 that of Ia+ B lymphoma cells, or B lymphoma cells expressing transfected class II genes. These I-A-expressing transfectants were tested for accessory cell function and shown to present polypeptide and complex protein antigens to T cell clones and hybridomas in the context of the transfected gene products. One T cell clone, restricted to I-Ak plus GAT (L-glutamic acid60-L-alanine30-L-tyrosine10), had a profound cytotoxic effect on I-Ak- but not I-Ad-expressing transfectants in the presence of specific antigen. Assays of unprimed T cells showed that both Ia+ and Ia- L cells could serve as accessory cells for concanavalin A-induced proliferative responses. These data indicate that L cells can transcribe, translate, and express transfected class II genes and that such I-A-bearing L cells possess the necessary metabolic mechanisms for presenting these antigens to T lymphocytes in the context of their I-A molecules. PMID:6436430

  15. Identification of a cis-acting element in the class I major histocompatibility complex gene promoter responsive to activation by retroviral sequences.

    PubMed Central

    Choi, S Y; van de Mark, K; Faller, D V

    1997-01-01

    The infection of cells with Moloney murine leukemia virus (M-MuLV) causes an increase in specific cellular gene products, including the major histocompatibility complex (MHC) class I antigens. This upregulation occurs through a transactivation process mediated by the long terminal repeat (LTR) of M-MuLV, and we show here that the gene activation response to the LTR requires at least one specific cis element within the MHC proximal promoter region. Nested deletions of MHC class I H-2Kb gene promoter sequence were subcloned into a chloramphenicol acetyltransferase (CAT) reporter vector and then transiently introduced into BALB/c-3T3 cells expressing M-MuLV or cotransfected into BALB/c-3T3 cells with a vector containing subgenomic portions of the virus, including the LTR. CAT activity assays demonstrated that a minimal H-2Kb gene promoter (-64 to +12) contained elements sufficient for this transactivation. DNase I footprinting assays located a protein-binding site in the region of -64 to -34 bp from the transcriptional start site, and point mutation analysis confirmed the location of this cis-acting element, designated the let response element (LRE), and defined a binding motif. This LRE is distinct from binding sites for currently known transcription factors in the class I MHC gene promoter and is conserved in the promoters of human and murine MHC class I genes. Mutation of the LRE resulted in dramatic reduction in both DNA-protein binding activity in electrophoretic mobility shift assay and in the ability of the mutated promoter to respond to retroviral transactivation. Addition of the LRE to a heterologous promoter conferred the ability to respond to retroviral transactivation. PMID:8995614

  16. Structure of a Complex of the Human α/β T Cell Receptor (TCR) HA1.7, Influenza Hemagglutinin Peptide, and Major Histocompatibility Complex Class II Molecule, HLA-DR4 (DRA*0101 and DRB1*0401)

    PubMed Central

    Hennecke, Jens; Wiley, Don C.

    2002-01-01

    The α/β T cell receptor (TCR) HA1.7 specific for the hemagglutinin (HA) antigen peptide from influenza A virus is HLA-DR1 restricted but cross-reactive for the HA peptide presented by the allo-major histocompatibility complex (MHC) class II molecule HLA-DR4. We report here the structure of the HA1.7/DR4/HA complex, determined by X-ray crystallography at a resolution of 2.4 Å. The overall structure of this complex is very similar to the previously reported structure of the HA1.7/DR1/HA complex. Amino acid sequence differences between DR1 and DR4, which are located deep in the peptide binding groove and out of reach for direct contact by the TCR, are able to indirectly influence the antigenicity of the pMHC surface by changing the conformation of HA peptide residues at position P5 and P6. Although TCR HA1.7 is cross-reactive for HA presented by DR1 and DR4 and tolerates these conformational differences, other HA-specific TCRs are sensitive to these changes. We also find a dependence of the width of the MHC class II peptide-binding groove on the sequence of the bound peptide by comparing the HA1.7/DR4/HA complex with the structure of DR4 presenting a collagen peptide. This structural study of TCR cross-reactivity emphasizes how MHC sequence differences can affect TCR binding indirectly by moving peptide atoms. PMID:11877480

  17. A new class of luminescent tricarbonyl rhenium(I) complexes containing bridging 1,2-diazine ligands: electrochemical, photophysical, and computational characterization.

    PubMed

    Donghi, Daniela; D'Alfonso, Giuseppe; Mauro, Matteo; Panigati, Monica; Mercandelli, Pierluigi; Sironi, Angelo; Mussini, Patrizia; D'Alfonso, Laura

    2008-05-19

    A novel class of luminescent tricarbonyl rhenium(I) complexes of general formula [Re2(mu-X)2(CO)6(mu-diaz)] (X=halogen and diaz=1,2-diazine) was prepared by reacting [ReX(CO)5] with 0.5 equiv of diazine (seven different ligands were used). The bridging coordination of the diazine in these dinuclear complexes was confirmed by single-crystal X-ray analysis. Cyclic voltammetry in acetonitrile showed for all the complexes (but the phthalazine derivative) a chemically and electrochemically reversible ligand-centered reduction, as well as a reversible metal-centered bielectronic oxidation. With respect to the prototypical luminescent [ReCl(CO)3(bpy)] complex, the oxidation is more difficult and the reduction easier (about +0.3 V), so that a similar highest occupied molecular orbital-lowest unoccupied molecular orbital gap is observed. All of the complexes exhibit photoluminescence at room temperature in solution, with broad unstructured emission from metal-to-ligand charge-transfer states, at lambda in the range 579-620 nm. Lifetimes (tau=20-2200 ns) and quantum yields (Phi up to 0.12) dramatically change upon varying the bridging ligand X and the diazine substituents: in particular, quantum yields decrease in the series Cl, Br, and I and in the presence of substituents at the alpha positions of the pyridazine ring. A combined density functional and time-dependent density functional study of the geometry, relative stability, electronic structure, and photophysical properties of all the pyridazine derivatives was performed. The nature of the excited states involved in the electronic absorption spectra was ascertained, and trends in the energy of the highest occupied and lowest unoccupied molecular orbitals upon changing the pyridazine substituents and the bridging halogen ligands were discussed. The observed emission properties of these complexes were shown to be related to a combination of steric and electronic factors affecting their ground-state geometry and their

  18. Chromatin reader Brd4 functions in Ig class switching as a repair complex adaptor of nonhomologous end-joining.

    PubMed

    Stanlie, Andre; Yousif, Ashraf S; Akiyama, Hideo; Honjo, Tasuku; Begum, Nasim A

    2014-07-03

    Class switch recombination (CSR) is a B cell-specific genomic alteration induced by activation-induced cytidine deaminase (AID)-dependent DNA break at the immunoglobulin heavy-chain locus, followed by repair. Although chromatin-associated factors in promoting AID-induced DNA break have been widely reported, the involvement of chromatin adaptors at the repair phase of CSR remains unknown. Here, we show that the acetylated histone reader Brd4 is critical for nonhomologous end-joining (NHEJ) repair of AID- and I-SceI-induced DNA breaks. Brd4 was recruited to the DNA break regions, and its depletion from the chromatin caused CSR impairment without affecting the DNA break generation. Inhibition of Brd4 suppressed the accumulation of 53BP1 and uracil DNA glycosylase at the switch regions, perturbed the switch junctional microhomology, and reduced Igh/c-myc translocation. We conclude that Brd4 serves as a chromatin platform required for the recruitment of repair components during CSR and general DNA damage. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Synthesis and properties of salen-aluminum complexes as a novel class of color-tunable luminophores.

    PubMed

    Hwang, Kyu Young; Kim, Hyoseok; Lee, Yoon Sup; Lee, Min Hyung; Do, Youngkyu

    2009-06-22

    Showing their true colors? Full emission color tuning in the visible region can be achieved with salen-aluminum complexes that are electronically modulated at C5 of the phenoxide ring in the salen moiety. Emission spectra for various substituents R(5) are shown (EWG: electron-withdrawing group, EDG: electron-donating group).A series of salen-aluminum complexes, [{(R(5))(2)-salen(3-tBu)(2)}Al(OC(6)H(4)-p-C(6)H(5))] (salen=N,N'-bis(salicylidene)ethylenediamine; R(5)=H (1), tBu (2), Br (3), Ph (4), OMe (5), NMe(2) (6)) and [{5,5'-(NMe(3))(2)-salen(3-tBu)(2)}Al(OC(6)H(4)-p-C(6)H(5))][OTf](2) (7; OTf=CF(3)SO(3)) that are electronically modulated directly at C5 of the phenoxide ring in the salen moiety has been prepared. The crystal structures of 1, 4, 6, and 7 determined by X-ray diffraction reveal distorted square-pyramidal geometries around the Al atoms. Complexes 1-7 are all air-stable in both the solid and solution states and have high thermal stability (decomp 313-338 degrees C). Differential scanning calorimetric analyses show that they can form amorphous glasses with glass transition temperatures of 95-132 degrees C depending on the C5 substituent. UV/Vis absorption spectra of the complexes exhibit major bands at lambda=338-413 nm assignable to salen-centered pi-pi* transitions with a gradual red shift of the absorption maximum wavelengths as the substituent is varied from an electron-withdrawing (NMe(3)) to an electron-donating group (NMe(2)). The maxima in the emission spectra of 1-7 occur over the entire visible region, ranging from lambda=438 nm for 7 to lambda=599 nm for 6, with high fluorescence quantum efficiencies of up to Phi=0.40 for 4 in solution. DFT calculations suggest that the low-energy electronic transitions in 1-7 are characterized by HOMO(-i)-LUMO(+1) (i=1 for 1-6 or i=4 for 7) transitions localized on the salen moiety, with much involvement of the C5 position in the HOMO(-i). Thus, the electronic alteration at the C5 position of the phenoxide

  20. The predisposition to type 1 diabetes linked to the human leukocyte antigen complex includes at least one non-class II gene.

    PubMed Central

    Lie, B A; Todd, J A; Pociot, F; Nerup, J; Akselsen, H E; Joner, G; Dahl-Jørgensen, K; Rønningen, K S; Thorsby, E; Undlien, D E

    1999-01-01

    The human leukocyte antigen (HLA) complex, encompassing 3.5 Mb of DNA from the centromeric HLA-DPB2 locus to the telomeric HLA-F locus on chromosome 6p21, encodes a major part of the genetic predisposition to develop type 1 diabetes, designated "IDDM1." A primary role for allelic variation of the class II HLA-DRB1, HLA-DQA1, and HLA-DQB1 loci has been established. However, studies of animals and humans have indicated that other, unmapped, major histocompatibility complex (MHC)-linked genes are participating in IDDM1. The strong linkage disequilibrium between genes in this complex makes mapping a difficult task. In the present paper, we report on the approach we have devised to circumvent the confounding effects of disequilibrium between class II alleles and alleles at other MHC loci. We have scanned 12 Mb of the MHC and flanking chromosome regions with microsatellite polymorphisms and analyzed the transmission of these marker alleles to diabetic probands from parents who were homozygous for the alleles of the HLA-DRB1, HLA-DQA1, and HLA-DQB1 genes. Our analysis, using three independent family sets, suggests the presence of an additional type I diabetes gene (or genes). This approach is useful for the analysis of other loci linked to common diseases, to verify if a candidate polymorphism can explain all of the association of a region or if the association is due to two or more loci in linkage disequilibrium with each other. PMID:10053014

  1. 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.

  2. 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.

  3. The murine cytomegalovirus immune evasion protein m4/gp34 forms biochemically distinct complexes with class I MHC at the cell surface and in a pre-Golgi compartment.

    PubMed

    Kavanagh, D G; Koszinowski, U H; Hill, A B

    2001-10-01

    We have recently demonstrated that the murine CMV (MCMV) gene m4 is an immune evasion gene that protects MCMV-infected targets from some virus-specific CTL clones. m4 encodes m4/gp34, a 34-kDa glycoprotein that binds to major histocompatibility complex class I in the endoplasmic reticulum and forms a detergent-stable complex that is exported to the surface of the cell. To investigate how m4/gp34 promotes CTL evasion, we analyzed the assembly and export of m4/gp34-K(b) complexes. We found that 50-70% of K(b) exported over the course of MCMV infection was m4/gp34 associated. Because these complexes are present at the cell surface, it is possible that m4 mediates CTL evasion by interfering with contact between class I and receptors on the T cell. In addition, we found that K(b) retained by the MCMV immune evasion gene m152 formed a novel type of complex with Endo H-sensitive m4/gp34; these complexes are distinguished from the exported complexes by being stable in 1% digitonin and unstable in 1% Nonidet P-40. Because this association occurs in a pre-Golgi compartment, m4/gp34 might also interfere with Ag presentation by affecting some aspect of class I assembly, such as peptide loading. Although m4/gp34 requires beta(2)-microglobulin to bind class I, there was no significant binding of m4/gp34 to beta(2)-microglobulin in the absence of class I H chain, demonstrating that m4/gp34 forms Nonidet P-40-stable complexes specifically with folded conformations of class I. We conclude that m4/gp34 promotes immune evasion by a novel mechanism involving altered assembly and/or T cell recognition of class I molecules.

  4. First report of major histocompatibility complex class II loci from the Amazon pink river dolphin (genus Inia).

    PubMed

    Martínez-Agüero, M; Flores-Ramírez, S; Ruiz-García, M

    2006-07-31

    We report the first major histocompatibility complex (MHC) DQB1 sequences for the two species of pink river dolphins (Inia geoffrensis and Inia boliviensis) inhabiting the Amazon and Orinoco River basins. These sequences were found to be polymorphic within the Inia genus and showed shared homology with cetacean DQB-1 sequences, especially, those of the Monodontidae and Phocoenidae. On the other hand, these sequences were shown to be divergent from those described for other riverine dolphin species, such as Lipotes vexillifer, the Chinese river dolphin. Two main conclusions can be drawn from our results: 1) the Mhc DQB1 sequences seem to evolve more rapidly than other nuclear sequences in cetaceans, and 2) differential positive selective pressures acting on these genes cause concomitant divergent evolutionary histories that derive phylogenetic reconstructions that could be inconsistent with widely accepted intertaxa evolutionary relationships elucidated with other molecular markers subjected to a neutral dynamics.

  5. Virus and cytotoxic T lymphocytes: crucial role of viral peptide secondary structure in major histocompatibility complex class I interactions.

    PubMed

    Gairin, J E; Oldstone, M B

    1993-05-01

    Viral antigens are presented to cytotoxic T lymphocytes (CTLs) by H-2-restricted major histocompatibility complex (MHC) glycoproteins. Binding of the endogenously processed viral peptides (epitopes) to their specific MHC molecules is an early intracellular event in the recognition process and is necessary for subsequent killing of virus-infected cells by virus-specific CTLs. It is now well established that interaction between a viral antigenic peptide and MHC is dependent on the primary structure (length and amino acid sequence) of that antigen. Here we show, using the H-2Db-restricted epitope GP277-286 of lymphocytic choriomeningitis virus as a model, that the secondary structure (conformation) of the viral sequence also plays a crucial role in the binding of a viral antigen to MHC glycoprotein and in its subsequent presentation to virus-specific CTLs.

  6. Virus and cytotoxic T lymphocytes: crucial role of viral peptide secondary structure in major histocompatibility complex class I interactions.

    PubMed Central

    Gairin, J E; Oldstone, M B

    1993-01-01

    Viral antigens are presented to cytotoxic T lymphocytes (CTLs) by H-2-restricted major histocompatibility complex (MHC) glycoproteins. Binding of the endogenously processed viral peptides (epitopes) to their specific MHC molecules is an early intracellular event in the recognition process and is necessary for subsequent killing of virus-infected cells by virus-specific CTLs. It is now well established that interaction between a viral antigenic peptide and MHC is dependent on the primary structure (length and amino acid sequence) of that antigen. Here we show, using the H-2Db-restricted epitope GP277-286 of lymphocytic choriomeningitis virus as a model, that the secondary structure (conformation) of the viral sequence also plays a crucial role in the binding of a viral antigen to MHC glycoprotein and in its subsequent presentation to virus-specific CTLs. PMID:7682632

  7. 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.

  8. Mycobacterium tuberculosis Synergizes with ATP To Induce Release of Microvesicles and Exosomes Containing Major Histocompatibility Complex Class II Molecules Capable of Antigen Presentation ▿ †

    PubMed Central

    Ramachandra, Lakshmi; Qu, Yan; Wang, Ying; Lewis, Colleen J.; Cobb, Brian A.; Takatsu, Kiyoshi; Boom, W. Henry; Dubyak, George R.; Harding, Clifford V.

    2010-01-01

    Major histocompatibility complex class II (MHC-II) molecules are released by murine macrophages upon lipopolysaccharide (LPS) stimulation and ATP signaling through the P2X7 receptor. These studies show that infection of macrophages with Mycobacterium tuberculosis or M. bovis strain BCG enhances MHC-II release in synergy with ATP. Shed MHC-II was contained in two distinct organelles, exosomes and plasma membrane-derived microvesicles, which were both able to present exogenous antigenic peptide to T hybridoma cells. Furthermore, microvesicles from mycobacterium-infected macrophages were able to directly present M. tuberculosis antigen (Ag) 85B(241-256)-I-Ab complexes that were generated by the processing of M. tuberculosis Ag 85B in infected cells to both M. tuberculosis-specific T hybridoma cells and naïve P25 M. tuberculosis T-cell receptor (TCR)-transgenic T cells. In the presence of prefixed macrophages, exosomes from mycobacterium-infected macrophages provided weak stimulation to M. tuberculosis-specific T hybridoma cells but not naïve P25 T cells. Thus, infection with M. tuberculosis primes macrophages for the increased release of exosomes and microvesicles bearing M. tuberculosis peptide-MHC-II complexes that may generate antimicrobial T-cell responses. PMID:20837713

  9. Major histocompatibility complex class II (MHC II) expression during the development of human fetal cerebral occipital lobe, cerebellum, and hematopoietic organs.

    PubMed

    Wierzba-Bobrowicz, T; Kosno-Kruszewska, E; Gwiazda, E; Lechowicz, W

    2000-01-01

    In adults, under physiological conditions proteins of the major histocompatibility complex, class II (MHC II) molecules are synthesized and then presented on the surface of the cells known under a common name as antigen presenting cells (APCs). Dendritic cells (DCs), microglia, macrophages, ameboid microglia and lymphocytes B are qualified as APCs. The aim of present study was to evaluate the expression of MHC II molecules in the central nervous system (CNS) and hematopoietic organs during the fetal development. Observations were made on the cerebral occipital lobe, cerebellum, thymus, spleen and liver of 30 normal human fetuses, between 11 and 22 week of gestation (GW). Histological, histochemical and immunohistochemical techniques were used to identify cells with expression of MHC II molecules. In the brain, MHC II molecules were detected on macrophages/ameboid microglia in meninges, choroid plexus and single cells of ramified microglia in deeper layers of the cortex and white matter. In the other organs besides macrophages and dendritic cells, MHC II molecules were also immunopositive in thymic epithelial cells, and in the spleen and liver also in other cells of stroma and lobule. The expression of MHC II molecules on so extensive population of cells, at an early stage of the fetal development, may evidence their significant involvement in histogenesis and morphogenesis. It seems that in adults the complex of MHC II with protein is originated from the foreign antigen. On the contrary, during normal fetal development the complex of MHC II with protein origins most probably from the fetus own structures.

  10. Enterobacter cloacae complex isolates harboring blaNMC-A or blaIMI-type class A carbapenemase genes on novel chromosomal integrative elements and plasmids.

    PubMed

    Boyd, David A; Mataseje, Laura F; Davidson, Ross; Delport, Johannes A; Fuller, Jeff; Hoang, Linda; Lefebvre, Brigitte; Levett, Paul; Roscoe, Diane L; Willey, Barbara M; Mulvey, Michael R

    2017-02-21

    Carbapenem-resistant Enterobacter cloacae complex isolates submitted to a reference laboratory from 2010 to 2015 were screened by PCR for seven common carbapenemase gene groups, namely, KPC, NDM, OXA-48, VIM, IMP, GES, and NMC-A/IMI. Nineteen of the submitted isolates (1.7%) were found to harbor Ambler class A blaNMC-A or blaIMI-type carbapenemases. All 19 isolates were resistant to at least one carbapenem but susceptible to aminoglycosides, trimethoprim-sulfamethoxazole, tigecycline, and ciprofloxacin. Most isolates (17/19) gave positive results with the Carba-NP test for phenotypic carbapenemase detection. Isolates were genetically diverse by pulsed-field gel electrophoresis macrorestriction analysis, multilocus sequence typing, and hsp60 gene analysis. The genes were found in various Enterobacter cloacae complex species, however blaNMC-A was highly associated with Enterobacter ludwiggii Whole genome sequencing and bioinformatics analysis revealed that all NMC-A (n=10), IMI-1 (n=5), and IMI-9 (n=2) producers harbored the carbapenemase gene on EludIMEX-1-like integrative mobile elements, EcloIMEXs, located in the identical chromosomal locus. Two novel genes, blaIMI-5 and blaIMI-6, were harbored on different IncFII-type plasmids. Enterobacter cloacae complex isolates harboring blaNMC-A/IMI-type carbapenemases are relatively rare in Canada. Though mostly found integrated into the chromosome, some variants are located on plasmids that may enhance their mobility potential.

  11. 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

  12. 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

    2015-03-02

    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.

  13. Differential immune response of congenic mice to ultraviolet-treated major histocompatibility complex class II-incompatible skin grafts

    SciTech Connect

    Vermeer, B.J.; Santerse, B.; Van De Kerckhove, B.A.; Schothorst, A.A.; Claas, F.H.

    1988-03-01

    The influence of ultraviolet (UVB) irradiation on the survival of H-2 class II-disparate skin grafts was studied in congenic mouse strains. Isolated skin was UVB irradiated in vitro at a dose of 40 mJ/cm/sup 2/ from both sides to remove Ia immunogenicity. Immediately after irradiation the skin was transplanted onto the flank of allogeneic mice. When B10.AQR grafts were transplanted onto B10.T(6R) recipients, a significant prolongation of the survival time was observed, while 50% of the UVB-treated grafts were not rejected at all. However, in the opposite direction--i.e., B10.T(6R) grafts onto B10.AQR recipients, no significant prolongation of the survival was observed. To test whether this effect was due to a difference in susceptibility of the donor skin to UVB irradiation or to a different immune response in the recipients, (B10.T(6R) x B10.AQR) grafts were transplanted onto the parent strains. Similar results were obtained, in that UVB-treated grafts did not show a prolonged survival in B10.AQR recipients, whereas a significant prolongation (50% of the grafts survived more than 100 days) was observed in B10.T(6R) recipients. UVB-treated (B10.T(6R) x B10.AQR)F1 grafts were also transplanted onto (B10.T(6R) x C57B1/10)F1, (B10.AQR x C57B1/10)F1, (B10.T(6R) x Balb/c)F1 and (B10.AQR x Balb/c)F1 recipients--but in none of these combinations was a prolonged survival time observed. These data suggest that, in contrast to all in vitro experiments, the abrogation of the immune response by UVB treatment of the stimulator cells is, in vivo, not a general phenomenon. The genetic constitution of the responder mice seems to play an important role in determining whether or not an immune response takes place.

  14. Major histocompatibility complex class II polymorphisms in forest musk deer (Moschus berezovskii) and their probable association with purulent disease.

    PubMed

    Li, L; Wang, B B; Ge, Y F; Wan, Q H

    2014-10-01

    Genes of the major histocompatibility complex (MHC) family are crucial in immune responses because they present pathogenic peptides to T cells. In this study, we analysed the genetic variation in forest musk deer (Moschus berezovskii) MHC II genes and its potential association with musk deer purulent disease. In total, 53 purulent disease-susceptible and 46 purulent disease-resistant individuals were selected for MHC II exon 2 fragment analysis. Among them, 16 DQ alleles and four additional DR alleles were identified, with DQ exon 2 fragments displaying a low level of polymorphism. The nonsynonymous substitutions exceeded the synonymous substitutions in the peptide-binding sites of DQA2, DQB1 and DQB2. Then, 28 MHC II alleles were used to analyse the distribution patterns of purulent disease between the susceptible and resistant groups. Among them, three alleles (DQA1*01, DQA1*02 and DQA2*04) were found to be resistant, and five alleles (DRB3*07, DQA1*03, DQA1*04, DQA2*05 and DQA2*06) were found to increase susceptibility. Additionally, three haplotypes were found to be putatively associated with musk deer purulent disease. However, these three haplotypes were only found in the resistant or susceptible group, and their frequencies were low. The results from our study support a contributory role of MHC II polymorphisms in the development of purulent disease in forest musk deer.

  15. Letermovir and inhibitors of the terminase complex: a promising new class of investigational antiviral drugs against human cytomegalovirus

    PubMed Central

    Melendez, Dante P; Razonable, Raymund R

    2015-01-01

    Infection with cytomegalovirus is prevalent in immunosuppressed patients. In solid organ transplant and hematopoietic stem cell transplant recipients, cytomegalovirus infection is associated with high morbidity and preventable mortality. Prevention and treatment of cytomegalovirus with currently approved antiviral drugs is often associated with side effects that sometimes preclude their use. Moreover, cytomegalovirus has developed mutations that confer resistance to standard antiviral drugs. During the last decade, there have been calls to develop novel antiviral drugs that could provide better options for prevention and treatment of cytomegalovirus. Letermovir (AIC246) is a highly specific antiviral drug that is currently undergoing clinical development for the management of cytomegalovirus infection. It acts by inhibiting the viral terminase complex. Letermovir is highly potent in vitro and in vivo against cytomegalovirus. Because of a distinct mechanism of action, it does not exhibit cross-resistance with other antiviral drugs. It is predicted to be active against strains that are resistant to ganciclovir, foscarnet, and cidofovir. To date, early-phase clinical trials suggest a very low incidence of adverse effects. Herein, we present a comprehensive review on letermovir, from its postulated novel mechanism of action to the results of most recent clinical studies. PMID:26345608

  16. Natural selection coupled with intragenic recombination shapes diversity patterns in the major histocompatibility complex class II genes of the giant panda.

    PubMed

    Chen, Yi-Yan; Zhang, Ying-Ying; Zhang, He-Min; Ge, Yun-Fa; Wan, Qiu-Hong; Fang, Sheng-Guo

    2010-05-15

    Ample variations of the major histocompatibility complex (MHC) genes are essential for vertebrates to adapt to various environmental conditions. In this study, we investigated the genetic variations and evolutionary patterns of seven functional MHC class II genes (one DRA, two DRB, two DQA, and two DQB) of the giant panda. The results showed the presence of two monomorphic loci (DRA and DQB2) and five polymorphic loci with different numbers of alleles (seven at DRB1, six at DRB3, seven at DQA1, four at DQA2, six at DQB1). The presence of balancing selection in the giant panda was supported by the following pieces of evidence: (1) The observed heterozygosity was higher than expected. (2) Amino acid heterozygosity was significantly higher at antigen-binding sites (ABS) compared with non-ABS sequences. (3) The selection parameter omega (d(N)/d(S)) was significantly higher at ABS compared with non-ABS sequences. (4) Approximately 95.45% of the positively selected codons (P>0.95) were located at or adjacent to an ABS. Furthermore, this study showed that (1) The Qinling subspecies exhibited high omega values across each locus (all >1), supporting its extensive positive selection. (2) The Sichuan subspecies displayed small omega at DRB1 (omega<0.72) and DQA2 (omega<0.48), suggesting that these sites underwent strong purifying selection. (3) Intragenic recombination was detected in DRB1, DQA1, and DQB1. The molecular diversity in classic Aime-MHC class II genes implies that the giant panda had evolved relatively abundant variations in its adaptive immunity along the history of host-pathogen co-evolution. Collectively, these findings indicate that natural selection accompanied by recombination drives the contrasting diversity patterns of the MHC class II genes between the two studied subspecies of giant panda.

  17. Firing patterns and functional roles of different classes of spinal afferents in rectal nerves during colonic migrating motor complexes in mouse colon.

    PubMed

    Zagorodnyuk, Vladimir P; Kyloh, Melinda; Brookes, Simon J; Nicholas, Sarah J; Spencer, Nick J

    2012-08-01

    The functional role of the different classes of visceral afferents that innervate the large intestine is poorly understood. Recent evidence suggests that low-threshold, wide-dynamic-range rectal afferents play an important role in the detection and transmission of visceral pain induced by noxious colorectal distension in mice. However, it is not clear which classes of spinal afferents are activated during naturally occurring colonic motor patterns or during intense contractions of the gut smooth muscle. We developed an in vitro colorectum preparation to test how the major classes of rectal afferents are activated during spontaneous colonic migrating motor complex (CMMC) or pharmacologically induced contraction. During CMMCs, circular muscle contractions increased firing in low-threshold, wide-dynamic-range muscular afferents and muscular-mucosal afferents, which generated a mean firing rate of 1.53 ± 0.23 Hz (n = 8) under isotonic conditions and 2.52 ± 0.36 Hz (n = 17) under isometric conditions. These low-threshold rectal afferents were reliably activated by low levels of circumferential stretch induced by increases in length (1-2 mm) or load (1-3 g). In a small proportion of cases (5 of 34 units), some low-threshold muscular and muscular-mucosal afferents decreased their firing rate during the peak of the CMMC contractions. High-threshold afferents were never activated during spontaneous CMMC contractions or tonic contractions induced by bethanechol (100 μM). High-threshold rectal afferents were only activated by intense levels of circumferential stretch (10-20 g). These results show that, in the rectal nerves of mice, low-threshold, wide-dynamic-range muscular and muscular-mucosal afferents are excited during contraction of the circular muscle that occurs during spontaneous CMMCs. No activation of high-threshold rectal afferents was detected during CMMCs or intense contractile activity in naïve mouse colorectum.

  18. 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. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Cost effective and time efficient measurement of CD4, CD8, major histocompatibility complex Class II, and macrophage antigen expression in the lungs of chickens.

    PubMed

    Fletcher, Oscar J; Tan, Xun; Cortes, Lucia; Gimeno, Isabel

    2012-05-15

    Cells expressing CD4, CD8, major histocompatibility complex (MHC) Class II, and macrophage biomarkers in lungs of chickens were quantified by measuring total area of antigen expressed using imageJ, a software program developed at the National Institutes of Health and available at no cost. The procedures reported here were rapid, and reproducible. Total area of antigen expressed had positive correlation with manual counts of cells expressing CD4 and CD8 biomarkers after inoculation with serotype 1 Marek's disease virus (MDV) vaccines. Visual inspection and overlays prepared from outlines of cells counted by imageJ confirmed agreement between antigen expression and area measured. Total area measured was not dependent on time of image acquisition from randomly selected fields from the same slides. Total area values were not computer specific, but acquisition of the original images required standardization of microscope used and camera setup. All steps in the process from sample collection through sectioning, staining, and image acquisition must be standardized as much as possible. Chickens infected with a very virulent+ (vv(+)) isolate of MDV (648A) had increased CD4, CD8, MHC Class II, and macrophage biomarker expression compared to noninfected control chickens at 10 days post infection, but variable responses depending on the specific biomarker measured at 3 and 5 days post infection. The procedure described here is faster and more reproducible than manual counting in cases (CD4 and CD8) where the number of positive cells is low enough for manual counts. Manual counting is not possible with MHC Class II and macrophage antigens nor when CD4(+) cells are present in large numbers following proliferation to tumors, thus subjective systems are used for scoring in these conditions. Using imageJ as described eliminates the need for subjective and less reproducible methods for measuring expression of these antigens.

  20. 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

  1. Class II major histocompatibility complex molecules regulate the development of the T4+T8- inducer phenotype of cultured human thymocytes.

    PubMed Central

    Blue, M L; Daley, J F; Levine, H; Schlossman, S F

    1985-01-01

    We demonstrate that a variety of Ia+ cells has the ability to promote the development of human T4+T8- thymocytes in vitro. Prolonged thymocyte culture in the absence of Ia+ accessory cells results in a predominantly T8+T4- cell population. The generation of T4+ cells in the presence of irradiated Ia+ cells could be suppressed up to 70% by a monoclonal antibody directed against a nonpolymorphic epitope on HLA-DR. Using two-color fluorescence sorting techniques, we were able to identify the activated T4+T8+ thymocyte as the cell that interacts with Ia and gives rise to the T4+T8- cell subset. These results directly and specifically implicate class II major histocompatibility complex molecules in the differentiative pathway of the human thymocyte. Images PMID:2933749

  2. Immune response genes controlling responsiveness to major transplantation antigens. Specific major histocompatibility complex-linked defect for antibody responses to class I alloantigens

    SciTech Connect

    Butcher, G.W.; Corvalan, J.R.; Licence, D.R.; Howard, J.C.

    1982-01-01

    We have identified two major histocompatibility complex (MHC)-linked Ir genes that control the antibody response made by rats against class I major alloantigens. We have named these genes Ir-RT1Aa and Ir-RT1Ac. These Ir genes determine responsiveness of the immunized animal in a typical codominant fashion. There is no evidence so far for trans-complementation between low-responder haplotypes. Detailed studies of Ir-RT1Aa indicate that it controls the antibody response to at least two distinct alloantigenic determinants on RT1Aa molecules. These class I molecules thus behave like hapten-carrier conjugates when the response against the carrier is under Ir gene control. Analysis of the origin of alloantibody-forming cells in tetraparental radiation chimeras indicates that Ir-RT1Aa must control the provision of effective help to B cells. In many respects therefore, the properties of Ir-RT1Aa are broadly similar to those described for Ir genes controlling antibody responses to conventional antigens. The existence of apparently conventional Ir genes controlling the antibody response to major alloantigens strongly suggest that the processing of these transmembrane molecules by host antigen-presenting cells is a prerequisite for immune induction, and that it is the MHC of the responder rather than that of the allograft to which T helper cells are restricted in alloimmune responses in vivo.

  3. A large protein containing zinc finger domains binds to related sequence elements in the enhancers of the class I major histocompatibility complex and kappa immunoglobulin genes.

    PubMed Central

    Baldwin, A S; LeClair, K P; Singh, H; Sharp, P A

    1990-01-01

    A cDNA from a B-cell library was previously isolated that encodes a sequence-specific DNA-binding protein with affinities for related sites in a class I major histocompatibility complex (MHC) and kappa immunoglobulin gene enhancers. We report here approximately 6.5 kilobases of sequence of the MBP-1 (MHC enhancer binding protein 1) cDNA. MBP-1 protein has a molecular weight predicted to be greater than 200,000. A DNA-binding domain with high affinity for the MHC enhancer sequence TGGGGATTCCCCA was localized to an 118-amino-acid protein fragment containing two zinc fingers of the class Cys2-X12-His2. Analysis of expression of MBP-1 mRNA revealed relatively high expression in HeLa cells and in a human retinal cell line, with lower levels in Jurkat T cells and in two B-cell lines. Interestingly, expression of MBP-1 mRNA was inducible by mitogen and phorbol ester treatment of Jurkat T cells and by serum treatment of confluent serum-deprived human fibroblasts. Images PMID:2108316

  4. Identification of a novel major histocompatibility complex class II-restricted tumor antigen resulting from a chromosomal rearrangement recognized by CD4(+) T cells.

    PubMed

    Wang, R F; Wang, X; Rosenberg, S A

    1999-05-17

    CD4(+) T cells play an important role in antitumor immune responses and autoimmune and infectious diseases. Although many major histocompatibility complex (MHC) class I-restricted tumor antigens have been identified in the last few years, little is known about MHC class II- restricted human tumor antigens recognized by CD4(+) T cells. Here, we describe the identification of a novel melanoma antigen recognized by an human histocompatibility leukocyte antigen (HLA)-DR1-restricted CD4(+) tumor-infiltrating lymphocyte (TIL)1363 using a genetic cloning approach. DNA sequencing analysis indicated that this was a fusion gene generated by a low density lipid receptor (LDLR) gene in the 5' end fused to a GDP-L-fucose:beta-D-galactoside 2-alpha-L-fucosyltransferase (FUT) in an antisense orientation in the 3' end. The fusion gene encoded the first five ligand binding repeats of LDLR in the NH2 terminus followed by a new polypeptide translated in frame with LDLR from the FUT gene in an antisense direction. Southern blot analysis showed that chromosomal DNA rearrangements occurred in the 1363mel cell line. Northern blot analysis detected two fusion RNA transcripts present only in the autologous 1363mel, but not in other cell lines or normal tissues tested. Two minimal peptides were identified from the COOH terminus of the fusion protein. This represents the first demonstration that a fusion protein resulting from a chromosomal rearrangement in tumor cells serves as an immune target recognized by CD4(+) T cells.

  5. COMPLEX STRUCTURE IN CLASS 0 PROTOSTELLAR ENVELOPES. III. VELOCITY GRADIENTS IN NON-AXISYMMETRIC ENVELOPES, INFALL, OR ROTATION?

    SciTech Connect

    Tobin, John J.; Hartmann, Lee; Bergin, Edwin; Chiang, Hsin-Fang; Looney, Leslie W.; Maret, Sebastien

    2012-03-20

    We present an interferometric kinematic study of morphologically complex protostellar envelopes based on observations of the dense gas tracers N{sub 2}H{sup +} and NH{sub 3}. The strong asymmetric nature of most envelopes in our sample leads us to question the common interpretation of velocity gradients as rotation, given the possibility of projection effects in the observed velocities. Several 'idealized' sources with well-ordered velocity fields and envelope structures are now analyzed in more detail. We compare the interferometric data to position-velocity (PV) diagrams of kinematic models for spherical rotating collapse and filamentary rotating collapse. For this purpose, we developed a filamentary parameterization of the rotating collapse model to explore the effects of geometric projection on the observed velocity structures. We find that most envelopes in our sample have PV structures that can be reproduced by an infalling filamentary envelope projected at different angles within the plane of the sky. The infalling filament produces velocity shifts across the envelope that can mimic rotation, especially when viewed at single-dish resolutions and the axisymmetric rotating collapse model does not uniquely describe any data set. Furthermore, if the velocities are assumed to reflect rotation, then the inferred centrifugal radii are quite large in most cases, indicating significant fragmentation potential or more likely another component to the line-center velocity. We conclude that ordered velocity gradients cannot be interpreted as rotation alone when envelopes are non-axisymmetric and that projected infall velocities likely dominate the velocity field on scales larger than 1000 AU.

  6. Polymorphism in the major histocompatibility complex (MHC class II B) genes of the Rufous-backed Bunting (Emberiza jankowskii)

    PubMed Central

    Li, Dan; Zhao, Yunjiao; Lin, Aiqing; Li, Shi; Feng, Jiang

    2017-01-01

    Genetic diversity is one of the pillars of conservation biology research. High genetic diversity and abundant genetic variation in an organism may be suggestive of capacity to adapt to various environmental changes. The major histocompatibility complex (MHC) is known to be highly polymorphic and plays an important role in immune function. It is also considered an ideal model system to investigate genetic diversity in wildlife populations. The Rufous-backed Bunting (Emberiza jankowskii) is an endangered species that has experienced a sharp decline in both population and habitat size. Many historically significant populations are no longer present in previously populated regions, with only three breeding populations present in Inner Mongolia (i.e., the Aolunhua, Gahaitu and Lubei557 populations). Efforts focused on facilitating the conservation of the Rufous-backed Bunting (Emberiza jankowskii) are becoming increasingly important. However, the genetic diversity of E. jankowskii has not been investigated. In the present study, polymorphism in exon 2 of the MHCIIB of E. jankowskii was investigated. This polymorphism was subsequently compared with a related species, the Meadow Bunting (Emberiza cioides). A total of 1.59 alleles/individual were detected in E. jankowskii and 1.73 alleles/individual were identified in E. cioides. The maximum number of alleles per individual from the three E. jankowskii populations suggest the existence of at least three functional loci, while the maximum number of alleles per individual from the three E. cioides populations suggest the presence of at least four functional loci. Two of the alleles were shared between the E. jankowskii and E. cioides. Among the 12 unique alleles identified in E. jankowskii, 10.17 segregating sites per allele were detected, and the nucleotide diversity was 0.1865. Among the 17 unique alleles identified in E. cioides, eight segregating sites per allele were detected, and the nucleotide diversity was 0

  7. Heterogenous graft rejection pathways in class I major histocompatibility complex-disparate combinations and their differential susceptibility to immunomodulation induced by intravenous presensitization with relevant alloantigens

    PubMed Central

    1991-01-01

    The present study investigates the heterogeneity of graft rejection pathways in class I major histocompatibility complex (MHC)-disparate combinations and the susceptibility of each pathway to immunomodulation induced by intravenous presensitization with alloantigens. Depletion of CD8+ T cells was induced by repeated administration of anti-CD8 monoclonal antibody. CD8+ T cell-depleted mice failed to generate anti- allo class I MHC cytotoxic T cell (CTL) responses but exhibited anti- allo class I MHC T cell responses, such as mixed lymphocyte reaction (MLR)/IL-2 production, that were induced by CD4+ T cells. In contrast, donor-specific intravenous presensitization (DSP), as a model of donor- specific transfusion, induced almost complete elimination of CD4+ and CD8+ T cell-mediated MLR/IL-2 production, whereas this regimen did not affect the generation of CTL responses induced by DSP-resistant elements (CD8+ CTL precursors and CD4+ CTL helpers). Prolongation of skin graft survival was not induced by either of the above two regimens alone, but by the combination of these. Prolonged graft survival was obtained irrespective of whether the administration of anti-CD8 antibody capable of eliminating CTL was started before or after DSP. The combination of DSP with injection of anti-CD4 antibody also effectively prolonged graft survival. However, this was the case only when the injection of antibody was started before DSP, because such antibody administration was capable of inhibiting the generation of CTL responses by eliminating DSP-resistant CD4+ CTL helpers. These results indicate that (a) the graft rejection in class I-disparate combinations is induced by CD8+ CTL-involved and -independent pathways that are resistant and susceptible to DSP, respectively; (b) DSP contributes to, but is not sufficient for, the prolongation of graft survival; and (c) the suppression of graft rejection requires an additional treatment for reducing DSP-resistant CTL responses. The results are

  8. Double bonds in motion: bis(oxazolinylmethyl)pyrroles and their metal-induced planarization to a new class of rigid chiral C2-symmetric complexes.

    PubMed

    Mazet, Clément; Gade, Lutz H

    2003-04-14

    The synthesis of a new class of chiral C(2)-symmetric tridentate N-donor ligands, a series of 2,5-bis(2-oxazolinylmethyl)pyrroles, was achieved in four steps starting from the known 2,5-bis(trimethylammoniomethyl)pyrrole diiodide (1). Reaction of 1 with NaCN in dimethyl sulfoxide gave 2,5-bis(cyanomethyl)pyrrole (2) cleanly, which was then cyclized with amino alcohols to give the 2,5-bis(2-oxazolinylmethyl)pyrroles 3 a-c (3 a: bis[2-(4,4'-dimethyl-5-hydrooxazolyl)methyl]pyrrole; 3 b: (S,S)-bis[2-(4-isopropyl-4,5-dihydrooxazolyl)methyl]pyrrole; 3 c: (S,S)-bis[2-(4-tertiobutyl-4,5-dihydrooxazolyl)methyl]pyrrole). Metallation of 3 a-c with one molar equivalent of tBuLi and their subsequent reaction with a stoichiometric amount of [PdCl(2)(cod)] (cod=cyclooctadiene) gave the palladium(II) complexes 4 a-c. Whereas the arrangement of the N-donor atoms in the crystallographically characterized complex 4 a is almost ideally square planar, all three heterocycles in the ligand are twisted out of the coordination plane, leading to a chiral conformation of the complex. Attempts to freeze out these two conformers in solution at 200 K (NMR) failed, and this suggests that the activation barrier for conformational racemization is significantly below 10 kcal mol(-1). The palladium-induced shift of two double bonds as well as the porphyrinogen/porphyrin-type oxidation of the complexes 4 a-c led to the planarization of the 2,5-bis(oxazolinylmethyl)pyrrolide ligands in the palladium(II) complexes 5 a-c, 6 b, and 6 c, and to the formation of rigid chiral C(2)-symmetric systems as shown by X-ray diffraction studies. The formation of the conjugated system of double bonds in this transformation is accompanied by the emergence of an intra-ligand chromophore. This is evident in the absorption spectrum of 6 c which displays an intense band with a maximum at 485 nm attributable to an intra-ligand pi*<--pi transition and a characteristic vibrational progression of nu approximately 1350 cm(-1

  9. 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

  10. The three-dimensional structure of the human Pi class glutathione transferase P1-1 in complex with the inhibitor ethacrynic acid and its glutathione conjugate.

    PubMed

    Oakley, A J; Rossjohn, J; Lo Bello, M; Caccuri, A M; Federici, G; Parker, M W

    1997-01-21

    The potent diuretic drug ethacrynic acid has been tested in clinical trials as an adjuvant in chemotherapy. Its target is the detoxifying enzyme glutathione transferase which is often found overexpressed in cancer tissues. We have solved the crystal structures of human pi class glutathione transferase P1-1 in complex with the inhibitor ethacrynic acid and its glutathione conjugate. Ethacrynic acid is found to bind in a nonproductive mode to one of the ligand binding sites of the enzyme (the H site) while the glutathione binding site (G site) is occupied by solvent molecules. There are no structural rearrangements of the G site in the absence of ligand. The structure indicates that bound glutathione is required for ethacrynic acid to dock into the H site in a productive binding mode. The binding of the ethacrynic acid-glutathione conjugate shows that the contacts of the glutathione moiety with the protein are identical to those observed in crystal structures of the enzyme with other glutathione-based substrates and inhibitors. The ethacrynic acid moiety of the conjugate binds in the H site in a fashion that has not been observed in crystal structures of other glutathione-based inhibitor complexes. The crystal structures implicate Tyr 108 as an electrophilic participant in the Michael addition of glutathione to ethacrynic acid.

  11. 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. PMID:27572108

  12. A novel class of bis- and tris-chelate diam(m)inebis(dicarboxylato)platinum(IV) complexes as potential anticancer prodrugs.

    PubMed

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

    2014-08-14

    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.

  13. Upregulation of class I major histocompatibility complex gene expression in primary sensory neurons, satellite cells, and Schwann cells of mice in response to acute but not latent herpes simplex virus infection in vivo

    PubMed Central

    1994-01-01

    Major histocompatibility complex (MHC) deficiency is typical of almost all resident cells in normal neural tissue. However, CD8+ T cells, which recognize antigenic peptides in the context of class I MHC molecules, are known to mediate clearance of herpes simplex virus (HSV) from spinal ganglia of experimentally infected mice, leading to the hypothesis that class I expression in the peripheral nervous system must be upregulated in response to HSV infection. In addressing this hypothesis it is shown, in BALB/c (H-2d) mice, that normally deficient class I transcripts transiently accumulate in peripheral nerve Schwann cells, ganglionic satellite cells, and primary sensory neurons, indicating that in each of these cell types class I expression is regulated at the transcriptional level in vivo. Furthermore, for 3-4 wk after infection, H-2Kd/Dd antigens are expressed by satellite and Schwann cells but not neurons, suggesting additional posttranscriptional regulation of class I synthesis in neurons. Alternatively, the class I RNAs induced in neurons may not be derived from classical class I genes. Factors regulating H-2 class I expression emanate from within infected ganglia, probably from infected neurons themselves. However, induction of class I molecules was not maintained during latency, when viral gene expression in neurons is restricted to a single region within the virus repeats. These data have implications for the long-term survival of cells in HSV-infected neural tissue. PMID:8064236

  14. Altered Expression of Raet1e, a Major Histocompatibility Complex Class 1–Like Molecule, Underlies the Atherosclerosis Modifier Locus Ath11 10b

    PubMed Central

    Rodríguez, José M.; Wolfrum, Susanne; Robblee, Megan; Chen, Kwan Y.; Gilbert, Zachary N.; Choi, Jae-Hoon; Teupser, Daniel; Breslow, Jan L.

    2014-01-01

    Rationale Quantitative trait locus mapping of an intercross between C57.Apoe−/− and FVB.Apoe−/− mice revealed an atherosclerosis locus controlling aortic root lesion area on proximal chromosome 10, Ath11. In a previous work, subcongenic analysis showed Ath11 to be complex with proximal (10a) and distal (10b) regions. Objective To identify the causative genetic variation underlying the atherosclerosis modifier locus Ath11 10b. Methods and Results We now report subcongenic J, which narrows the 10b region to 5 genes, Myb, Hbs1L, Aldh8a1, Sgk1, and Raet1e. Sequence analysis of these genes revealed no amino acid coding differences between the parental strains. However, comparing aortic expression of these genes between F1.Apoe−/− Chr10SubJ(B/F) and F1.Apoe−/− Chr10SubJ(F/F) uncovered a consistent difference only for Raet1e, with decreased, virtually background, expression associated with increased atherosclerosis in the latter. The key role of Raet1e was confirmed by showing that transgene-induced aortic overexpression of Raet1e in F1.Apoe−/− Chr10SubJ(F/F) mice decreased atherosclerosis. Promoter reporter constructs comparing C57 and FVB sequences identified an FVB mutation in the core of the major aortic transcription start site abrogating activity. Conclusions This nonbiased approach has revealed Raet1e, a major histocompatibility complex class 1–like molecule expressed in lesional aortic endothelial cells and macrophage-rich regions, as a novel atherosclerosis gene and represents one of the few successes of the quantitative trait locus strategy in complex diseases. PMID:23948654

  15. A Mutational Analysis of the Binding of Staphylococcal Enterotoxins B and C3 to the T Cell Receptor β Chain and Major Histocompatibility Complex Class II

    PubMed Central

    Leder, Lukas; Llera, Andrea; Lavoie, Pascal M.; Lebedeva, Marina I.; Li, Hongmin; Sékaly, Rafick-Pierre; Bohach, Gregory A.; Gahr, Pamala J.; Schlievert, Patrick M.; Karjalainen, Klaus; Mariuzza, Roy A.

    1998-01-01

    The three-dimensional structure of the complex between a T cell receptor (TCR) β chain (mouse Vβ8.2Jβ2.1Cβ1) and the superantigen (SAG) staphylococcal enterotoxin C3 (SEC3) has been recently determined to 3.5 Å resolution. To evaluate the actual contribution of individual SAG residues to stabilizing the β–SEC3 complex, as well as to investigate the relationship between the affinity of SAGs for TCR and MHC and their ability to activate T cells, we measured the binding of a set of SEC3 and staphylococcal enterotoxin B (SEB) mutants to soluble recombinant TCR β chain and to the human MHC class II molecule HLA-DR1. Affinities were determined by sedimentation equilibrium and/or surface plasmon detection, while mitogenic potency was assessed using T cells from rearrangement-deficient TCR transgenic mice. We show that there is a clear and simple relationship between the affinity of SAGs for the TCR and their biological activity: the tighter the binding of a particular mutant of SEC3 or SEB to the TCR β chain, the greater its ability to stimulate T cells. We also find that there is an interplay between TCR–SAG and SAG–MHC interactions in determining mitogenic potency, such that a small increase in the affinity of a SAG for MHC can overcome a large decrease in the SAG's affinity for the TCR. Finally, we observe that those SEC3 residues that make the greatest energetic contribution to stabilizing the β–SEC3 complex (“hot spot” residues) are strictly conserved among enterotoxins reactive with mouse Vβ8.2, thereby providing a basis for understanding why SAGs having other residues at these positions show different Vβ-binding specificities. PMID:9500785

  16. "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…

  17. Crystal Structures of Three Classes of Non-Steroidal Anti-Inflammatory Drugs in Complex with Aldo-Keto Reductase 1C3

    PubMed Central

    Flanagan, Jack U.; Yosaatmadja, Yuliana; Teague, Rebecca M.; Chai, Matilda Z. L.; Turnbull, Andrew P.; Squire, Christopher J.

    2012-01-01

    Aldo-keto reductase 1C3 (AKR1C3) catalyses the NADPH dependent reduction of carbonyl groups in a number of important steroid and prostanoid molecules. The enzyme is also over-expressed in prostate and breast cancer and its expression is correlated with the aggressiveness of the disease. The steroid products of AKR1C3 catalysis are important in proliferative signalling of hormone-responsive cells, while the prostanoid products promote prostaglandin-dependent proliferative pathways. In these ways, AKR1C3 contributes to tumour development and maintenance, and suggest that inhibition of AKR1C3 activity is an attractive target for the development of new anti-cancer therapies. Non-steroidal anti-inflammatory drugs (NSAIDs) are one well-known class of compounds that inhibits AKR1C3, yet crystal structures have only been determined for this enzyme with flufenamic acid, indomethacin, and closely related analogues bound. While the flufenamic acid and indomethacin structures have been used to design novel inhibitors, they provide only limited coverage of the NSAIDs that inhibit AKR1C3 and that may be used for the development of new AKR1C3 targeted drugs. To understand how other NSAIDs bind to AKR1C3, we have determined ten crystal structures of AKR1C3 complexes that cover three different classes of NSAID, N-phenylanthranilic acids (meclofenamic acid, mefenamic acid), arylpropionic acids (flurbiprofen, ibuprofen, naproxen), and indomethacin analogues (indomethacin, sulindac, zomepirac). The N-phenylanthranilic and arylpropionic acids bind to common sites including the enzyme catalytic centre and a constitutive active site pocket, with the arylpropionic acids probing the constitutive pocket more effectively. By contrast, indomethacin and the indomethacin analogues sulindac and zomepirac, display three distinctly different binding modes that explain their relative inhibition of the AKR1C family members. This new data from ten crystal structures greatly broadens the base of

  18. Structural Requirements for Recognition of Major Histocompatibility Complex Class II by Membrane-associated RING-CH (MARCH) Protein E3 Ligases*

    PubMed Central

    Jahnke, Martin; Trowsdale, John; Kelly, Adrian P.

    2012-01-01

    MARCH E3 ligases play a key role in controlling MHC class II surface expression by regulated ubiquitination of a lysine residue in the β-chain. Little is known concerning how these enzymes target their specific substrates. Here we show that recognition of HLA-DR by MARCH proteins is complex. Several features associated with the transmembrane domain and bordering regions influence the overall efficiency of receptor internalization. A cluster of residues at the interface of the lipid bilayer and the cytosol plays the most important role in MARCH8 recognition of HLA-DRβ. Variation in this sequence also determines specificity of MARCH9 for HLA-DQ. Residues located in helical face four of HLA-DRβ together with a charged residue at the boundary with the stalk region also contribute significantly to recognition. Truncation analysis suggested that a dileucine-like motif in the DRβ cytoplasmic tail influences the efficiency of co-localization of HLA-DR with MARCH8. The DRβ-encoded acceptor lysine functioned optimally when placed in its natural location relative to the bilayer. In the DRα/DRβ dimer most other amino acids in the cytoplasmic tail could be substituted for alanine with minimal influence on function. Our data support a model whereby multiple features of HLA-DR are involved in substrate recognition by MARCH8. The single most important region is located at the interface between the transmembrane domain and the cytosol. Variation in sequence in this location between different class II isotypes controls efficiency of recognition by different MARCH E3 ligases. PMID:22761441

  19. Comparative genome analysis of the major histocompatibility complex (MHC) class I B/C segments in primates elucidated by genomic sequencing in common marmoset (Callithrix jacchus).

    PubMed

    Shiina, Takashi; Kono, Azumi; Westphal, Nico; Suzuki, Shingo; Hosomichi, Kazuyoshi; Kita, Yuki F; Roos, Christian; Inoko, Hidetoshi; Walter, Lutz

    2011-08-01

    Common marmoset monkeys (Callithrix jacchus) have emerged as important animal models for biomedical research, necessitating a more extensive characterization of their major histocompatibility complex (MHC) region. However, the genomic information of the marmoset MHC (Caja) is still lacking. The MHC-B/C segment represents the most diverse MHC region among primates. Therefore, in this paper, to elucidate the detailed gene organization and evolutionary processes of the Caja class I B (Caja-B) segment, we determined two parts of the Caja-B sequences with 1,079 kb in total, ranging from H6orf15 to BAT1 and compared the structure and phylogeny with that of other primates. This segment contains 54 genes in total, nine Caja-B genes (Caja-B1 to Caja-B9), two MIC genes (MIC1 and MIC2), eight non-MHC genes, two non-coding genes, and 33 non-MHC pseudogenes that have not been observed in other primate MHC-B/C segments. Caja-B3, Caja-B4, and Caja-B7 encode proper MHC class I proteins according to amino acid structural characteristics. Phylogenetic relationships based on 48 MHC-I nucleotide sequences in primates suggested (1) species-specific divergence for Caja, Mamu, and HLA/Patr/Gogo lineages, (2) independent generation of the "seven coding exon" type MHC-B genes in Mamu and HLA/Patr/Gogo lineages from an ancestral "eight coding exon" type MHC-I gene, (3) parallel correlation with the long and short segmental duplication unit length in Caja and Mamu lineages. These findings indicate that the MHC-B/C segment has been under permanent selective pressure in the evolution of primates.

  20. Identification of a Novel Major Histocompatibility Complex Class II–restricted Tumor Antigen Resulting from a Chromosomal Rearrangement Recognized by CD4+ T Cells

    PubMed Central

    Wang, Rong-Fu; Wang, Xiang; Rosenberg, Steven A.

    1999-01-01

    CD4+ T cells play an important role in antitumor immune responses and autoimmune and infectious diseases. Although many major histocompatibility complex (MHC) class I–restricted tumor antigens have been identified in the last few years, little is known about MHC class II– restricted human tumor antigens recognized by CD4+ T cells. Here, we describe the identification of a novel melanoma antigen recognized by an human histocompatibility leukocyte antigen (HLA)-DR1–restricted CD4+ tumor-infiltrating lymphocyte (TIL)1363 using a genetic cloning approach. DNA sequencing analysis indicated that this was a fusion gene generated by a low density lipid receptor (LDLR) gene in the 5′ end fused to a GDP-l-fucose:β-d-galactoside 2-α-l-fucosyltransferase (FUT) in an antisense orientation in the 3′ end. The fusion gene encoded the first five ligand binding repeats of LDLR in the NH2 terminus followed by a new polypeptide translated in frame with LDLR from the FUT gene in an antisense direction. Southern blot analysis showed that chromosomal DNA rearrangements occurred in the 1363mel cell line. Northern blot analysis detected two fusion RNA transcripts present only in the autologous 1363mel, but not in other cell lines or normal tissues tested. Two minimal peptides were identified from the COOH terminus of the fusion protein. This represents the first demonstration that a fusion protein resulting from a chromosomal rearrangement in tumor cells serves as an immune target recognized by CD4+ T cells. PMID:10330445

  1. Masking of a cathepsin G cleavage site in vivo contributes to the proteolytic resistance of major histocompatibility complex class II molecules

    PubMed Central

    Burster, Timo; Macmillan, Henriette; Hou, Tieying; Schilling, James; Truong, Phi; Boehm, Bernhard O; Zou, Fang; Lau, Kenneth; Strohman, Michael; Schaffert, Steven; Busch, Robert; Mellins, Elizabeth D

    2010-01-01

    The expression of major histocompatibility complex class II (MHC II) molecules is post-translationally regulated by endocytic protein turnover. Here, we identified the serine protease cathepsin G (CatG) as an MHC II-degrading protease by in vitro screening and examined its role in MHC II turnover in vivo. CatG, uniquely among endocytic proteases tested, initiated cleavage of detergent-solubilized native and recombinant soluble MHC II molecules. CatG cleaved human leukocyte antigen (HLA)-DR isolated from both HLA-DM-expressing and DM-null cells. Even following CatG cleavage, peptide binding was retained by pre-loaded, soluble recombinant HLA-DR. MHC II cleavage occurred on the loop between fx1 and fx2 of the membrane-proximal β2 domain. All allelic variants of HLA-DR tested and murine I-Ag7 class II molecules were susceptible, whereas murine I-Ek and HLA-DM were not, consistent with their altered sequence at the P1’ position of the CatG cleavage site. CatG effects were reduced on HLA-DR molecules with DRB mutations in the region implicated in interaction with HLA-DM. In contrast, addition of CatG to intact B-lymphoblastoid cell lines (B-LCLs) did not cause degradation of membrane-bound MHC II. Moreover, inhibition or genetic ablation of CatG in primary antigen-presenting cells did not cause accumulation of MHC II molecules. Thus, in vivo, the CatG cleavage site is sterically inaccessible or masked by associated molecules. A combination of intrinsic and context-dependent proteolytic resistance may allow peptide capture by MHC II molecules in harshly proteolytic endocytic compartments, as well as persistent antigen presentation in acute inflammatory settings with extracellular proteolysis. PMID:20331476

  2. Presence of strong association of the major histocompatibility complex (MHC) class I allele HLA-A*26:01 with idiopathic hypoparathyroidism.

    PubMed

    Goswami, Ravinder; Singh, Archana; Gupta, Nandita; Rani, Rajni

    2012-09-01

    The pathogenesis of isolated hypoparathyroidism, also referred to as idiopathic hypoparathyroidism (IH), is not clear. There is a paucity of information related to the immunogenetic basis of the disease due to its rarity. A recurrent theme of several autoimmune disorders is aberrant antigen presentation. We investigated for the association of alleles of the human leukocyte antigen (HLA) class I and II loci with IH. A total of 134 patients with IH and 902 healthy controls from the same ethnic background participated in the study. There was a significant increase of HLA class I alleles HLA-A*26:01 [P < 1.71 × 10(-34); odds ratio (OR) = 9.29; 95% confidence interval (CI) = 6.08-14.16] and HLA-B*08:01 (P < 8.19 × 10(-6); OR = 2.59; 95% CI = 1.63-4.04) in patients with IH compared to healthy controls. However, the association of A*26:01 was primary because B*08:01 was in linkage disequilibrium with A*26:01. Although the major histocompatibility complex (MHC) is very polymorphic, several alleles of HLA loci share key residues at anchor positions in the peptide binding pockets such that similar peptides may be presented by different MHC molecules encoded by the same locus. These allelic forms with similar anchoring amino acids have been clustered in supertypes. An analysis of HLA-A locus supertypes A01, A02, A03, and A04 revealed that supertype A01 was significantly increased (P < 9.18 × 10(-9); OR = 2.95) in IH compared to controls. However, this increase in the supertype A01 was contributed by A*26:01 because 68.7% of the A01 samples had A*26:01. Other alleles of the supertype did not show any significant differences. The strong association of HLA-A*26:01 suggests an important role of MHC class I-mediated presentation of autoantigenic peptides to CD8(+) cytotoxic T cells in the pathogenesis of IH. These data provide evidence for the autoimmune etiology of IH akin to other autoimmune disorders like type 1 diabetes and rheumatoid arthritis.

  3. Genomic resistance island AGI1 carrying a complex class 1 integron in a multiply antibiotic-resistant ST25 Acinetobacter baumannii isolate.

    PubMed

    Hamidian, Mohammad; Holt, Kathryn E; Hall, Ruth M

    2015-09-01

    The objective of this study was to locate the antibiotic resistance determinants in the multiply antibiotic-resistant Acinetobacter baumannii isolate D4. The genome was sequenced using Illumina HiSeq and assembled de novo using Velvet. PCR was used to link the relevant contigs and fill the gaps. Sequences were compared with ones in GenBank and annotated. A sporadic A. baumannii isolate D4, recovered in Sydney in 2006 from a wound, was multiply antibiotic resistant. D4 is ST25 (Institut Pasteur scheme) and exhibited resistance to third-generation cephalosporins and reduced susceptibility to ciprofloxacin, as well as resistance to aminoglycosides (gentamicin, kanamycin, neomycin and tobramycin) and further older antibiotics, nalidixic acid, sulfamethoxazole, streptomycin, spectinomycin and trimethoprim. The gyrA gene has a mutation consistent with nalidixic acid resistance. The bla PER conferring cephalosporin resistance, together with the aadB, aadA13/2, aadA2, strAB and sul1 resistance genes, are located within a 29 173 bp complex class 1 integron that includes three copies of intI1, three cassette arrays and two copies of the 3'-conserved segment. This integron is adjacent to the resG gene of an integrative genomic resistance island, AGI1 (Acinetobacter genomic island 1), with a backbone related to that of islands in the SGI1, SGI2 and PGI1 families. AGI1 is located at the 3'-end of the chromosomal trmE (formerly thdF) gene. AGI1 represents a new lineage of genomic resistance islands that belongs in the same broad group as members of the SGI1, SGI2 and PGI1 families. Genes conferring resistance to cephalosporins, aminoglycosides and sulphonamides are located in a complex class 1 integron within AGI1. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  4. A new class of transition metal pincer ligand: tantalum complexes that feature a [CCC] X3-donor array derived from a terphenyl ligand.

    PubMed

    Sattler, Aaron; Parkin, Gerard

    2012-02-01

    A new class of [CCC] X(3)-donor pincer ligand for transition metals has been constructed via cyclometalation of a 2,6-di-p-tolylphenyl ([Ar(Tol(2))]) derivative. Specifically, addition of PMe(3) to [Ar(Tol(2))]TaMe(3)Cl induces elimination of methane and formation of the pincer complex, [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)MeCl (Tol' = C(6)H(3)Me), which may also be obtained by treatment of Ta(PMe(3))(2)Me(3)Cl(2) with [Ar(Tol(2))]Li. Solutions of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)MeCl undergo ligand redistribution with the formation of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)Me(2)and [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)Cl(2), which may also be synthesized by the reactions of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)MeCl with MeMgBr and ZnCl(2), respectively. Reduction of [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)Cl(2) with KC(8) in benzene gives the benzene complex [κ(3)-Ar(Tol'(2))]Ta(PMe(3))(2)(η(6)-C(6)H(6)) that is better described as a 1,4-cyclohexadienediyl derivative. Deuterium labeling employing Ta(PMe(3))(2)(CD(3))(3)Cl(2) demonstrates that the pincer ligand is created by a pair of Ar-H/Ta-Me sigma-bond metathesis transformations, rather than by a mechanism that involves α-H abstraction by a tantalum methyl ligand. © 2012 American Chemical Society

  5. Optimal lymphocytic choriomeningitis virus sequences restricted by H-2Db major histocompatibility complex class I molecules and presented to cytotoxic T lymphocytes.

    PubMed

    Gairin, J E; Mazarguil, H; Hudrisier, D; Oldstone, M B

    1995-04-01

    Infection with lymphocytic choriomeningitis virus induces the generation of CD8+ cytotoxic T lymphocytes (CTL). In the H-2b mouse, this cellular immune response is directed against three viral structural epitopes (GP1, GP2, and NP) presented by the major histocompatibility complex (MHC) class I H-2Db molecules. This study was undertaken to delineate which sequence of each of these three epitopes is optimal for MHC binding and CTL recognition. The first step was to synthesize the relevant peptides truncated at the N or C terminus and flanking the crucial H-2Db-anchoring Asn residue in position 5. These peptides were then tested (i) for their binding properties in two H-2Db-specific assays with viable cells (upregulation of H-2Db expression on the surface of RMA-S cells and competition against the Db-restricted peptide 125I-gp276-286 on T2-Db cells) and (ii) for their abilities to sensitize H-2b target cells for CTL lysis in vitro. For optimal antigenic presentation, all three epitopes required the MHC-anchoring Asn residue at position 5 of their sequences. The results clearly and unambiguously delineated optimal lengths for two of the epitopes and two options for the third. NP appeared as a conventional 9-amino-acid (aa)-long peptide, np396-404 (FQPQNGQFI). GP2 was defined as a longer peptide (11 aa), gp276-286 (SGVENPGGYCL). Characterization of the GP1 epitope was more complex: the 9-aa-long peptide gp33-41 (KAVYNFATC) and the carboxyl-extended 11-aa-long peptide gp33-43 (KAVYN FATCGI) were both established as possible optimal sequences depending on the cell line used to test binding and lysis.

  6. Optimal lymphocytic choriomeningitis virus sequences restricted by H-2Db major histocompatibility complex class I molecules and presented to cytotoxic T lymphocytes.

    PubMed Central

    Gairin, J E; Mazarguil, H; Hudrisier, D; Oldstone, M B

    1995-01-01

    Infection with lymphocytic choriomeningitis virus induces the generation of CD8+ cytotoxic T lymphocytes (CTL). In the H-2b mouse, this cellular immune response is directed against three viral structural epitopes (GP1, GP2, and NP) presented by the major histocompatibility complex (MHC) class I H-2Db molecules. This study was undertaken to delineate which sequence of each of these three epitopes is optimal for MHC binding and CTL recognition. The first step was to synthesize the relevant peptides truncated at the N or C terminus and flanking the crucial H-2Db-anchoring Asn residue in position 5. These peptides were then tested (i) for their binding properties in two H-2Db-specific assays with viable cells (upregulation of H-2Db expression on the surface of RMA-S cells and competition against the Db-restricted peptide 125I-gp276-286 on T2-Db cells) and (ii) for their abilities to sensitize H-2b target cells for CTL lysis in vitro. For optimal antigenic presentation, all three epitopes required the MHC-anchoring Asn residue at position 5 of their sequences. The results clearly and unambiguously delineated optimal lengths for two of the epitopes and two options for the third. NP appeared as a conventional 9-amino-acid (aa)-long peptide, np396-404 (FQPQNGQFI). GP2 was defined as a longer peptide (11 aa), gp276-286 (SGVENPGGYCL). Characterization of the GP1 epitope was more complex: the 9-aa-long peptide gp33-41 (KAVYNFATC) and the carboxyl-extended 11-aa-long peptide gp33-43 (KAVYN FATCGI) were both established as possible optimal sequences depending on the cell line used to test binding and lysis. PMID:7533855

  7. Engineered regulatory T cells coexpressing MHC class II:peptide complexes are efficient inhibitors of autoimmune T cell function and prevent the development of autoimmune arthritis.

    PubMed

    Qian, Zhaohui; Latham, Kary A; Whittington, Karen B; Miller, David C; Brand, David D; Rosloniec, Edward F

    2013-06-01

    Regulatory T cells (Tregs) are critical homeostatic components in preventing the development of autoimmunity, and are a major focus for their therapeutic potential for autoimmune diseases. To enhance the efficacy of Tregs in adoptive therapy, we developed a strategy for generating engineered Tregs that have the capacity to target autoimmune T cells in an Ag-specific manner. Using a retroviral expression system encoding Foxp3 and HLA-DR1 covalently linked to the immunodominant peptide of the autoantigen type II collagen (DR1-CII), naive T cells were engineered to become Tregs that express DR1-CII complexes on their surface. When these cells were tested for their ability to prevent the development of collagen induced arthritis, both the engineered DR1-CII-Foxp3 and Foxp3 only Tregs significantly reduced the severity and incidence of disease. However, the mechanism by which these two populations of Tregs inhibited disease differed significantly. Disease inhibition by the DR1-CII-Foxp3 Tregs was accompanied by significantly lower numbers of autoimmune CII-specific T cells in vivo and lower levels of autoantibodies in comparison with engineered Tregs expressing Foxp3 alone. In addition, the numbers of IFN-γ- and IL-17-expressing T cells in mice treated with DR1-CII-Foxp3 Tregs were also significantly reduced in comparison with mice treated with Foxp3 engineered Tregs or vector control cells. These data indicate that the coexpression of class II autoantigen-peptide complexes on Tregs provides these cells with a distinct capacity to regulate autoimmune T cell responses that differs from that used by conventional Tregs.

  8. Engineered Tregulatory cells co-expressing MHC class II:peptide complexes are efficient inhibitors of autoimmune T cell function and prevent the development of autoimmune arthritis

    PubMed Central

    Qian, Zhaohui; Latham, Kary A.; Whittington, Karen B.; Miller, David C.; Brand, David D.; Rosloniec, Edward F.

    2013-01-01

    Treg cells are critical homeostatic components in preventing the development of autoimmunity, and are a major focus for their therapeutic potential for autoimmune diseases. In order to enhance the efficacy of Treg cells in adoptive therapy, we developed a strategy for generating engineered Tregs that have the capacity to target autoimmune T cells in an antigen specific manner. Using a retroviral expression system encoding Foxp3 and HLA-DR1 covalently linked to the immunodominant peptide of the autoantigen type II collagen (DR1-CII), naïve T cells were engineered to become Treg cells that express DR1-CII complexes on their surface. When these cells were tested for their ability to prevent the development of collagen induced arthritis, both the engineered DR1-CII-Foxp3 and Foxp3 only Treg cells significantly reduced the severity and incidence of disease. However, the mechanism buy which these two populations of Treg cells inhibited disease differed significantly. Disease inhibition by the DR1-CII-Foxp3 Treg cells was accompanied by significantly lower numbers of autoimmune CII-specific T cells in vivo and lower levels of autoantibodies in comparison to engineered Tregs expressing Foxp3 alone. Additionally, the numbers of IFN-γ and IL-17 expressing T cells in mice treated with DR1-CII-Foxp3 Tregs were also significantly reduced in comparison to mice treated with Foxp3 engineered Treg cells or vector control cells. These data indicate that the co-expression of class II autoantigen-peptide complexes on Treg cells provides these cells with a distinct capacity to regulate autoimmune T cell responses that differs from that used by conventional Treg cells. PMID:23630354

  9. Crystal Structure of Fushi Tarazu Factor 1 Ligand Binding Domain/Fushi Tarazu Peptide Complex Identifies New Class of Nuclear Receptors*

    PubMed Central

    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

    2011-01-01

    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

  10. Improved binding activity of antibodies against major histocompatibility complex class I chain-related gene A by phage display technology for cancer-targeted therapy.

    PubMed

    Phumyen, Achara; Jumnainsong, Amonrat; Leelayuwat, Chanvit

    2012-01-01

    Major histocompatibility complex class I chain-related gene A (MICA) is an NKG2D ligand that is over-expressed under cellular stress including cancer transformation and viral infection. High expression of MICA in cancer tissues or patients' sera is useful for prognostic or follow-up markers in cancer patients. In this study, phage display technology was employed to improve antigen-binding activities of anti-MICA monoclonal antibodies (WW2G8, WW6B7, and WW9B8). The 12 amino acid residues in the complementarity determining regions (CDRs) on the V domain of the heavy chain CDR3 (HCDR3) of these anti-MICA antibodies were modified by PCR-random mutagenesis, and phages displaying mutated anti-MICA Fab were constructed. After seven rounds of panning, five clones of phages displaying mutant anti-MICA Fab which exhibited 3-7-folds higher antigen-binding activities were isolated. Two clones of the mutants (phage-displayed mutant Fab WW9B8.1 and phage-displayed mutant Fab WW9B8.21) were confirmed to have antigen-binding specificity for cell surface MICA proteins by flow cytometry. These phage clones are able to recognize MICA in a native form according to positive results obtained by indirect ELISA and flow cytometry. Thus, these phage particles could be potentially used for further development of nanomedicine specifically targeting cancer cells expressing MICA proteins.

  11. 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. © The American Genetic Association 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Malaria protection in β2-microglobulin-deficient mice lacking major histocompatibility complex class I antigens: essential role of innate immunity, including γδT cells

    PubMed Central

    Taniguchi, Tomoyo; Tachikawa, Saoko; Kanda, Yasuhiro; Kawamura, Toshihiko; Tomiyama-Miyaji, Chikako; Li, Changchun; Watanabe, Hisami; Sekikawa, Hiroho; Abo, Toru

    2007-01-01

    It is still controversial whether malaria protection is mediated by conventional immunity associated with T and B cells or by innate immunity associated with extrathymic T cells and autoantibody-producing B cells. Given this situation, it is important to examine the mechanism of malaria protection in β2-microglobulin-deficient (β2m(–/–)) mice. These mice lack major histocompatibility complex class I and CD1d antigens, which results in the absence of CD8+ T cells and natural killer T (NKT) cells. When C57BL/6 and β2m(–/–) mice were injected with parasitized (Plasmodium yoelii 17XNL) erythrocytes, both survived from the infection and showed a similar level of parasitaemia. The major expanding T cells were NK1.1– αβΤ-cell receptorint cells in both mice. The difference was a compensatory expansion of NK and γδT cells in β2m(–/–) mice, and an elimination experiment showed that these lymphocytes were critical for protection in these mice. These results suggest that malaria protection might be events of the innate immunity associated with multiple subsets with autoreactivity. CD8+ T and NKT cells may be partially related to this protection. PMID:17916163

  13. Transcription of non-classic major histocompatibility complex (MHC) class I in the bovine placenta throughout gestation and after Brucella abortus infection.

    PubMed

    Dos Santos, Larissa Sarmento; da Silva Mol, Juliana Pinto; de Macedo, Auricélio Alves; Silva, Ana Patrícia Carvalho; Dos Santos Ribeiro, Diego Luiz; Santos, Renato Lima; da Paixão, Tatiane Alves; de Carvalho Neta, Alcina Vieira

    2015-10-15

    Transcription of non-classical major histocompatibility complex class I (MHC-I) was assessed in the bovine placenta throughout gestation. Additionally, the effect of Brucella abortus infection on expression of non-classical MHC-I was also evaluated using a chorioallantoic membrane explant model of infection. The non-classical MHC-I genes MICB and NC3 had higher levels of transcription in the intercotyledonary region when compared to the placentome, which had higher levels of transcription at the second trimester of gestation. NC1 and classical MHC-I had very low levels of transcription throughout gestation. Trophoblastic cells of B. abortus-infected chorioallantoic membrane explants had an increase in transcription of non-classical MHC-I at 4h post infection. Therefore, this study provides an analysis of non-classical MHC-I transcription at different stages of gestation and different placental tissues, and during B. abortus infection. These findings provide additional knowledge on immune regulation in placental tissues, a known immune-privileged site.

  14. Improved Binding Activity of Antibodies against Major Histocompatibility Complex Class I Chain-Related Gene A by Phage Display Technology for Cancer-Targeted Therapy

    PubMed Central

    Phumyen, Achara; Jumnainsong, Amonrat; Leelayuwat, Chanvit

    2012-01-01

    Major histocompatibility complex class I chain-related gene A (MICA) is an NKG2D ligand that is over-expressed under cellular stress including cancer transformation and viral infection. High expression of MICA in cancer tissues or patients' sera is useful for prognostic or follow-up markers in cancer patients. In this study, phage display technology was employed to improve antigen-binding activities of anti-MICA monoclonal antibodies (WW2G8, WW6B7, and WW9B8). The 12 amino acid residues in the complementarity determining regions (CDRs) on the V domain of the heavy chain CDR3 (HCDR3) of these anti-MICA antibodies were modified by PCR-random mutagenesis, and phages displaying mutated anti-MICA Fab were constructed. After seven rounds of panning, five clones of phages displaying mutant anti-MICA Fab which exhibited 3–7-folds higher antigen-binding activities were isolated. Two clones of the mutants (phage-displayed mutant Fab WW9B8.1 and phage-displayed mutant Fab WW9B8.21) were confirmed to have antigen-binding specificity for cell surface MICA proteins by flow cytometry. These phage clones are able to recognize MICA in a native form according to positive results obtained by indirect ELISA and flow cytometry. Thus, these phage particles could be potentially used for further development of nanomedicine specifically targeting cancer cells expressing MICA proteins. PMID:23226940

  15. Techniques to improve the direct ex vivo detection of low frequency antigen-specific CD8+ T cells with peptide-major histocompatibility complex class I tetramers

    PubMed Central

    Chattopadhyay, Pratip K.; Melenhorst, J. Joseph; Ladell, Kristin; Gostick, Emma; Scheinberg, Philip; Barrett, A. John; Wooldridge, Linda; Roederer, Mario; Sewell, Andrew K.; Price, David A.

    2008-01-01

    The ability to quantify and characterize antigen-specific CD8+ T cells irrespective of functional readouts using fluorochrome-conjugated tetrameric peptide-MHC class I (pMHCI) complexes in conjunction with flow cytometry has transformed our understanding of cellular immune responses over the past decade. In the case of prevalent CD8+ T cell populations that engage cognate pMHCI tetramers with high avidities, direct ex vivo identification and subsequent data interpretation is relatively straightforward. However, the accurate identification of low frequency antigen-specific CD8+ T cell populations can be complicated, especially in situations where TCR-mediated tetramer binding occurs at low avidities. Here, we highlight a few simple techniques that can be employed to improve the visual resolution, and hence the accurate quantification, of tetramer-binding CD8+ T cell populations by flow cytometry. These methodological modifications enhance signal intensity, especially in the case of specific CD8+ T cell populations that bind cognate antigen with low avidity, minimize background noise and enable improved discrimination of true pMHCI tetramer binding events from nonspecific uptake. PMID:18836993

  16. Specific Capture of Peptide-Receptive Major Histocompatibility Complex Class I Molecules by Antibody Micropatterns Allows for a Novel Peptide-Binding Assay in Live Cells.

    PubMed

    Dirscherl, Cindy; Palankar, Raghavendra; Delcea, Mihaela; Kolesnikova, Tatiana A; Springer, Sebastian

    2017-02-02

    Binding assays with fluorescently labeled ligands and recombinant receptor proteins are commonly performed in 2D arrays. But many cell surface receptors only function in their native membrane environment and/or in a specific conformation, such as they appear on the surface of live cells. Thus, receptors on live cells should be used for ligand binding assays. Here, it is shown that antibodies preprinted on a glass surface can be used to specifically array a peptide receptor of the immune system, i.e., the major histocompatibility complex class I molecule H-2K(b) , into a defined pattern on the surface of live cells. Monoclonal antibodies make it feasible to capture a distinct subpopulation of H-2K(b) and hold it at the cell surface. This patterned receptor enables a novel peptide-binding assay, in which the specific binding of a fluorescently labeled index peptide is visualized by microscopy. Measurements of ligand binding to captured cell surface receptors in defined confirmations apply to many problems in cell biology and thus represent a promising tool in the field of biosensors.

  17. Partial plasma cell differentiation as a mechanism of lost major histocompatibility complex class II expression in diffuse large B-cell lymphoma.

    PubMed

    Wilkinson, Sarah T; Vanpatten, Kristie A; Fernandez, Diane R; Brunhoeber, Patrick; Garsha, Karl E; Glinsmann-Gibson, Betty J; Grogan, Thomas M; Teruya-Feldstein, Julie; Rimsza, Lisa M

    2012-02-09

    Loss of major histocompatibility complex class II (MHC II) expression is associated with poor patient outcome in diffuse large B-cell lymphoma (DLBCL). As MHC II molecules are lost with plasmacytic differentiation in normal cells, we asked whether MHC II loss in DLBCL is associated with an altered differentiation state. We used gene expression profiling, quantum dots, and immunohistochemistry to study the relationship between MHC II and plasma cell markers in DLBCL and plasmablastic lymphoma (PBL). Results demonstrate that MHC II(-) DLBCL immunophenotypically overlap with PBL and demonstrate an inverse correlation between MHC II and plasma cell markers MUM1, PRDM1/Blimp1, and XBP1s. In addition, MHC II expression is significantly higher in germinal center-DLBCL than activated B cell-DLBCL. A minor subset of cases with an unusual pattern of mislocalized punctate MHC II staining and intermediate levels of mRNA is also described. Finally, we show that PBL is negative for MHC II. The results imply a spectrum of MHC II expression that is more frequently diminished in tumors derived from B cells at the later stages of differentiation (with complete loss in PBL). Our observations provide a possible unifying concept that may contribute to the poor outcome reported in all MHC II(-) B-cell tumors.

  18. Extensive polymorphism and evidence of selection pressure on major histocompatibility complex DLA-DRB1, DQA1 and DQB1 class II genes in Croatian grey wolves.

    PubMed

    Arbanasić, H; Huber, Đ; Kusak, J; Gomerčić, T; Hrenović, J; Galov, A

    2013-01-01

    The genes of the major histocompatibility complex (MHC) are a key component of the mammalian immune system and have become important molecular markers for measuring fitness-related genetic variation in wildlife populations. Because of human persecution and habitat fragmentation, the grey wolf has become extinct from a large part of Western and Central Europe, and remaining populations have become isolated. In Croatia, the grey wolf population, part of the Dinaric-Balkan population, shrank nearly to extinction during the 20th century, and is now legally protected. Using the cloning-sequencing method, we investigated the genetic diversity and evolutionary history of exon 2 of MHC class II DLA-DRB1, DQA1 and DQB1 genes in 77 individuals. We identified 13 DRB1, 7 DQA1 and 11 DQB1 highly divergent alleles, and 13 DLA-DRB1/DQA1/DQB1 haplotypes. Selection analysis comparing the relative rates of non-synonymous to synonymous mutations (d(N)/d(S)) showed evidence of positive selection pressure acting on all three loci. Trans-species polymorphism was found, suggesting the existence of balancing selection. Evolutionary codon models detected considerable difference between alpha and beta chain gene selection patterns: DRB1 and DQB1 appeared to be under stronger selection pressure, while DQA1 showed signs of moderate selection. Our results suggest that, despite the recent contraction of the Croatian wolf population, genetic variability in selectively maintained immune genes has been preserved.

  19. The effects of historical fragmentation on major histocompatibility complex class II β and microsatellite variation in the Aegean island reptile, Podarcis erhardii.

    PubMed

    Santonastaso, Trent; Lighten, Jackie; van Oosterhout, Cock; Jones, Kenneth L; Foufopoulos, Johannes; Anthony, Nicola M

    2017-07-01

    The major histocompatibility complex (MHC) plays a key role in disease resistance and is the most polymorphic gene region in vertebrates. Although habitat fragmentation is predicted to lead to a loss in MHC variation through drift, the impact of other evolutionary forces may counter this effect. Here we assess the impact of selection, drift, migration, and recombination on MHC class II and microsatellite variability in 14 island populations of the Aegean wall lizard Podarcis erhardii. Lizards were sampled from islands within the Cyclades (Greece) formed by rising sea levels as the last glacial maximum approximately 20,000 before present. Bathymetric data were used to determine the area and age of each island, allowing us to infer the corresponding magnitude and timing of genetic bottlenecks associated with island formation. Both MHC and microsatellite variation were positively associated with island area, supporting the hypothesis that drift governs neutral and adaptive variation in this system. However, MHC but not microsatellite variability declined significantly with island age. This discrepancy is likely due to the fact that microsatellites attain mutation-drift equilibrium more rapidly than MHC. Although we detected signals of balancing selection, recombination and migration, the effects of these evolutionary processes appeared negligible relative to drift. This study demonstrates how land bridge islands can provide novel insights into the impact of historical fragmentation on genetic diversity as well as help disentangle the effects of different evolutionary forces on neutral and adaptive diversity.

  20. Techniques to improve the direct ex vivo detection of low frequency antigen-specific CD8+ T cells with peptide-major histocompatibility complex class I tetramers.

    PubMed

    Chattopadhyay, Pratip K; Melenhorst, J Joseph; Ladell, Kristin; Gostick, Emma; Scheinberg, Phillip; Barrett, A John; Wooldridge, Linda; Roederer, Mario; Sewell, Andrew K; Price, David A

    2008-11-01

    The ability to quantify and characterize antigen-specific CD8+ T cells irrespective of functional readouts using fluorochrome-conjugated peptide-major histocompatibility complex class I (pMHCI) tetramers in conjunction with flow cytometry has transformed our understanding of cellular immune responses over the past decade. In the case of prevalent CD8+ T cell populations that engage cognate pMHCI tetramers with high avidities, direct ex vivo identification and subsequent data interpretation is relatively straightforward. However, the accurate identification of low frequency antigen-specific CD8+ T cell populations can be complicated, especially in situations where T cell receptor-mediated tetramer binding occurs at low avidities. Here, we highlight a few simple techniques that can be employed to improve the visual resolution, and hence the accurate quantification, of tetramer binding CD8+ T cell populations by flow cytometry. These methodological modifications enhance signal intensity, especially in the case of specific CD8+ T cell populations that bind cognate antigen with low avidities, minimize background noise, and enable improved discrimination of true pMHCI tetramer binding events from nonspecific uptake.

  1. Recognition of the HLA class II-peptide complex by T-cell receptor: reversal of major histocompatibility complex restriction of a T-cell clone by a point mutation in the peptide determinant.

    PubMed

    Rothbard, J B; Busch, R; Lechler, R; Trowsdale, J; Lamb, J R

    1989-06-12

    Recognition of the HLA DR-peptide complex by an influenza haemagglutinin-specific T-cell clone was examined by assaying a variety of peptide analogues for their ability to be recognized. Consistent with earlier experiments arguing that the peptide blinds the restriction element in a helical conformation, acetylation of the amino terminus and amidation of the carboxy terminus of the natural determinant (residues 307-319) resulted in a peptide that exhibited both greater propensity to form a helix, as judged by circular dichroism, and the ability to stimulate the clone at concentrations approximately two orders of magnitude lower than the native sequence. The peptide was modelled into the potential antigen-combining site of HLA class II based on the ability of analogues containing point mutations to stimulate the T-cell clone. The working model was initially tested by examining the ability of Epstein-Barr-transformed B-cell lines expressing in different DR4 subtypes to present the native haemagglutinin sequence and analogues to the clone. The different alleles could be categorized as high, intermediate, or low responders based on the resulting proliferation. DR4 dw15 was a high-responding allele, dw4, 13, and 14 were intermediate-responding alleles, whereas dw10 was a low responder. Mutation of Gln to Arg at 312 in the haemagglutinin sequence converted the high and intermediate responders to non-responders, while turning the low-responding allele into an intermediate responder. Potential explanations for these effects are discussed in the context of the model of the complex between peptide and the major histocompatibility complex.

  2. Diverse peptide presentation of rhesus macaque major histocompatibility complex class I Mamu-A 02 revealed by two peptide complex structures and insights into immune escape of simian immunodeficiency virus.

    PubMed

    Liu, Jun; Dai, Lianpan; Qi, Jianxun; Gao, Feng; Feng, Youjun; Liu, Wenjun; Yan, Jinghua; Gao, George F

    2011-07-01

    Major histocompatibility complex class I (MHC I)-restricted CD8(+) T-cell responses play a pivotal role in anti-human immunodeficiency virus (HIV) immunity and the control of viremia. The rhesus macaque is an important animal model for HIV-related research. Among the MHC I alleles of the rhesus macaque, Mamu-A 02 is prevalent, presenting in ≥20% of macaques. In this study, we determined the crystal structure of Mamu-A 02, the second structure-determined MHC I from the rhesus macaque after Mamu-A 01. The peptide presentation characteristics of Mamu-A 02 are exhibited in complex structures with two typical Mamu-A 02-restricted CD8(+) T-cell epitopes, YY9 (Nef159 to -167; YTSGPGIRY) and GY9 (Gag71 to -79; GSENLKSLY), derived from simian immunodeficiency virus (SIV). These two peptides utilize similar primary anchor residues (Ser or Thr) at position 2 and Tyr at position 9. However, the central region of YY9 is different from that of GY9, a difference that may correlate with the immunogenic variance of these peptides. Further analysis indicated that the distinct conformations of these two peptides are modulated by four flexible residues in the Mamu-A 02 peptide-binding groove. The rare combination of these four residues in Mamu-A 02 leads to a variant presentation for peptides with different residues in their central regions. Additionally, in the two structures of the Mamu-A 02 complex, we compared the binding of rhesus and human β(2) microglobulin (β(2)m) to Mamu-A 02. We found that the peptide presentation of Mamu-A 02 is not affected by the interspecies interaction with human β(2)m. Our work broadens the understanding of CD8(+) T-cell-specific immunity against SIV in the rhesus macaque.

  3. Diverse Peptide Presentation of Rhesus Macaque Major Histocompatibility Complex Class I Mamu-A*02 Revealed by Two Peptide Complex Structures and Insights into Immune Escape of Simian Immunodeficiency Virus ▿

    PubMed Central

    Liu, Jun; Dai, Lianpan; Qi, Jianxun; Gao, Feng; Feng, Youjun; Liu, Wenjun; Yan, Jinghua; Gao, George F.

    2011-01-01

    Major histocompatibility complex class I (MHC I)-restricted CD8+ T-cell responses play a pivotal role in anti-human immunodeficiency virus (HIV) immunity and the control of viremia. The rhesus macaque is an important animal model for HIV-related research. Among the MHC I alleles of the rhesus macaque, Mamu-A*02 is prevalent, presenting in ≥20% of macaques. In this study, we determined the crystal structure of Mamu-A*02, the second structure-determined MHC I from the rhesus macaque after Mamu-A*01. The peptide presentation characteristics of Mamu-A*02 are exhibited in complex structures with two typical Mamu-A*02-restricted CD8+ T-cell epitopes, YY9 (Nef159 to -167; YTSGPGIRY) and GY9 (Gag71 to -79; GSENLKSLY), derived from simian immunodeficiency virus (SIV). These two peptides utilize similar primary anchor residues (Ser or Thr) at position 2 and Tyr at position 9. However, the central region of YY9 is different from that of GY9, a difference that may correlate with the immunogenic variance of these peptides. Further analysis indicated that the distinct conformations of these two peptides are modulated by four flexible residues in the Mamu-A*02 peptide-binding groove. The rare combination of these four residues in Mamu-A*02 leads to a variant presentation for peptides with different residues in their central regions. Additionally, in the two structures of the Mamu-A*02 complex, we compared the binding of rhesus and human β2 microglobulin (β2m) to Mamu-A*02. We found that the peptide presentation of Mamu-A*02 is not affected by the interspecies interaction with human β2m. Our work broadens the understanding of CD8+ T-cell-specific immunity against SIV in the rhesus macaque. PMID:21561910

  4. Assembly and cell surface expression of TAP-independent, chloroquine-sensitive and interferon-gamma-inducible class I MHC complexes in transformed fibroblast cell lines are regulated by tapasin.

    PubMed

    Fromm, Sharon Vigodman; Duady-Ben Yaakov, Shirly; Schechter, Chana; Ehrlich, Rachel

    2002-02-01

    Antigen processing and presentation by class I MHC molecules generally require assembly with peptide epitopes generated by the proteasome and transported into the ER by the transporters associated with antigen presentation (TAP). Recently, TAP-independent pathways supporting class I MHC-mediated presentation of exogenous antigens, as well as of endogenously synthesized viral antigens, were described. We now characterize a TAP-independent pathway that is operative in both TAP1- and TAP2-deficient Adenovirus (Ad)-transformed fibroblast cell lines. To the best of our knowledge, this is the first time that the existence of such a pathway has been described in non-infected cells that do not belong to the hematopoietic lineage. We show that this pathway is proteasome-independent and chloroquine-sensitive. Cell surface expression of these TAP-independent class I complexes is modulated by tapasin levels and is enhanced by IFN-gamma. The data imply that IFN-gamma increases the relative level of TAP-independent high affinity class I complexes that exit the ER on their way to the cell surface and to vacuolar compartments where peptide cleavage/exchange might take place before recycling to the cell surface. Since both TAP and tapasin expression are altered in numerous tumors and in virus-infected cells, TAP-independent class I complexes may be a valuable target source for immune responses.

  5. Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Inhibits Major Histocompatibility Complex Class II Expression by Disrupting Enhanceosome Assembly through Binding with the Regulatory Factor X Complex

    PubMed Central

    Thakker, Suhani; Purushothaman, Pravinkumar; Gupta, Namrata; Challa, Shanthan; Cai, Qiliang

    2015-01-01

    ABSTRACT Major histocompatibility complex class II (MHC-II) molecules play a central role in adaptive antiviral immunity by presenting viral peptides to CD4+ T cells. Due to their key role in adaptive immunity, many viruses, including Kaposi's sarcoma-associated herpesvirus (KSHV), have evolved multiple strategies to inhibit the MHC-II antigen presentation pathway. The expression of MHC-II, which is controlled mainly at the level of transcription, is strictly dependent upon the binding of the class II transactivator (CIITA) to the highly conserved promoters of all MHC-II genes. The recruitment of CIITA to MHC-II promoters requires its direct interactions with a preassembled MHC-II enhanceosome consisting of cyclic AMP response element-binding protein (CREB) and nuclear factor Y (NF-Y) complex and regulatory factor X (RFX) complex proteins. Here, we show that KSHV-encoded latency-associated nuclear antigen (LANA) disrupts the association of CIITA with the MHC-II enhanceosome by binding to the components of the RFX complex. Our data show that LANA is capable of binding to all three components of the RFX complex, RFX-associated protein (RFXAP), RFX5, and RFX-associated ankyrin-containing protein (RFXANK), in vivo but binds more strongly with the RFXAP component in in vitro binding assays. Levels of MHC-II proteins were significantly reduced in KSHV-infected as well as LANA-expressing B cells. Additionally, the expression of LANA in a luciferase promoter reporter assay showed reduced HLA-DRA promoter activity in a dose-dependent manner. Chromatin immunoprecipitation assays showed that LANA binds to the MHC-II promoter along with RFX proteins and that the overexpression of LANA disrupts the association of CIITA with the MHC-II promoter. These assays led to the conclusion that the interaction of LANA with RFX proteins interferes with the recruitment of CIITA to MHC-II promoters, resulting in an inhibition of MHC-II gene expression. Thus, the data presented here identify

  6. CLASS for Class.

    NASA Astrophysics Data System (ADS)

    Bluestein, Howard B.

    1993-09-01

    Faculty and students from the School of Meteorology at the University of Oklahoma and staff members from the Atmospheric Technology Division at the National Center for Atmospheric Research (NCAR) participated in a special course given during the last two weeks of May 1992. The purpose of the course was to give students the opportunity to use the NCAR mobile CLASS (Cross-Chain LORAN Atmospheric Sounding System) in the field and to interpret data they collected themselves in the context of material learned earlier in a lecture setting. Soundings were obtained in parts of Texas and Oklahoma in the environment of multicell storms, in supercells, in a gust front, and on the cold side of a cold front.

  7. Molecular characterization of major histocompatibility complex class I (B-F) mRNA variants from chickens differing in resistance to Marek's disease.

    PubMed

    Dalgaard, T S; Vitved, L; Skjødt, K; Thomsen, B; Labouriau, R; Jensen, K H; Juul-Madsen, H R

    2005-09-01

    In this study, the relative distributions of two alternatively polyadenylated chicken major histocompatibility complex (MHC) mRNA isoforms of approximately 1.5 and 1.9 kb were analysed in spleen cells from chickens homozygous for the MHC haplotypes B21 and B19v1 as well as in heterozygous B19v1/B21 birds. Both isoforms are likely to encode classical MHC class I (B-F) alpha chains. The B19v1 and B21 MHC haplotypes confer different levels of protection against Marek's disease (MD), which is caused by infection with MD virus (MDV). In spleen cells, MD-resistant B21 birds were shown to have the highest percentage of the 1.5 kb variant relative to the total MHC class I expression, MD-susceptible B19v1 birds the lowest and B19v1/B21 birds an intermediate percentage. Infection of 4-week-old chickens with the GA strain of MDV was shown to cause a significant increase in the relative amount of 1.5 kb transcripts in B21 birds 32 days postinfection (dpi). Alternatively polyadenylated mRNA isoforms may encode identical proteins, but differences in the 3' untranslated region (UTR) can influence polyadenylation, mRNA stability, intracellular localization and translation efficiency. It was shown that the increased 1.5 kb percentage in B21 birds 32 days postinfection may be a result of a change in the choice of poly(A) site rather than a locus-specific upregulated transcription of the BF1 gene that preferentially expresses the 1.5 kb variant. Furthermore, the 3' end of the 1.5 kb mRNA variants deriving from B19v1 and B21 chickens was characterized by Rapid Amplification of cDNA Ends (RACE) and sequencing. No potentially functional elements were identified in the 3' UTR of the RACE products corresponding to this short isoform. However, variation in polyadenylation site was observed between the BF1 and BF2 mRNA transcripts and alternative splicing-out of the sequence (exon 7) encoding the second segment of the cytoplasmic part of the mature BF2*19 molecules. This alternative exon 7

  8. 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

  9. Gastric mucosal hyperplasia via upregulation of gastrin induced by persistent activation of gastric innate immunity in major histocompatibility complex class II deficient mice

    PubMed Central

    Fukui, T; Nishio, A; Okazaki, K; Uza, N; Ueno, S; Kido, M; Inoue, S; Kitamura, H; Kiriya, K; Ohashi, S; Asada, M; Tamaki, H; Matsuura, M; Kawasaki, K; Suzuki, K; Uchida, K; Fukui, H; Nakase, H; Watanabe, N; Chiba, T

    2006-01-01

    Background and aim Major histocompatibility complex class II deficient (Aα0/0) mice have decreased CD4+ T cells, making them immunologically similar to patients with acquired immunodeficiency syndrome (AIDS). Both patients with AIDS and Aα0/0 mice have hypertrophic gastric folds. To clarify the mechanism of gastric mucosal hyperplasia, we investigated the pathophysiology and the role of the innate immunity in the stomach of Aα0/0 mice. Methods Stomachs from 1–6 month old Aα0/0 mice, kept under specific pathogen free conditions, were examined at 1 month intervals histologically and immunohistochemically. Gene expression of proinflammatory cytokines, Toll‐like receptors (TLRs), cyclooxygenase (COX)‐2, and myeloperoxidase (MPO) activity in the gastric mucosa was investigated. Serum gastrin levels and gastric acidity were measured. Bacterial culture of the stomach was performed. To clarify the roles of hypergastrinaemia in the gastric mucosa, a gastrin receptor antagonist (AG041R) was administered. Results Aα0/0 mice had a diffusely thick corpus mucosa with infiltration of CD11b+ granulocytes and macrophages. Anti‐Ki67 staining demonstrated expansion of the proliferating neck zone. Gene expression of interleukin 1β, interferon γ, TLR‐2, TLR‐4, and COX‐2 were upregulated, and MPO activity was increased. Only a small amount of non‐pathogenic bacteria was detected in the stomach. Serum gastrin levels and Reg‐Iα positive cells in the gastric mucosa increased, despite normal gastric acidity. After treatment with AG041R, gastric mucosal thickness was significantly reduced. Conclusion Persistent activation of innate immunity in the stomach induced gastric mucosal hyperplasia through upregulation of gastrin synthesis in Aα0/0 mice, suggesting a pathophysiology similar to the gastric changes in patients with AIDS. PMID:16322110

  10. Short communication: Establishment of a new polymerase chain reaction-sequence-based typing method for genotyping cattle major histocompatibility complex class II DRB3.

    PubMed

    Takeshima, S-N; Matsumoto, Y; Aida, Y

    2009-06-01

    Sequence-based typing (SBT) is the most comprehensive method for characterizing major histocompatibility complex (MHC) gene polymorphisms. We report here a new PCR-SBT method for genotyping cattle MHC (BoLA) class II DRB3 using the Assign 400ATF ver. 1.0.2.41 software (Conexio Genomics, Fremantle, Australia), which detects alleles in a semiautomated manner. We examined 12 sets of PCR reactions for their ability to amplify BoLA-DRB3 exon 2 and selected an optimal primer set, which used ERB3N-HL031 for first-round PCR and ALL-DRB3B for second-round PCR. Next, we constructed a BoLA-DRB3 allele database using the reference sequences of the Assign 400ATF software and successfully assigned heterozygous samples (including those with deletion alleles) using bidirectional sequencing, unlike our previously described method, which used unidirectional sequencing for detecting of deletion alleles. Next, blood samples of 128 Holstein cattle were used to correlate the results of our modified PCR-SBT method with those of our previously described PCR-SBT method. Each new PCR-SBT result corresponded completely with the DRB3 allele that was genotyped by our previously described PCR-SBT method. Moreover, we confirmed the accuracy of our modified PCR-SBT method by genotyping 7 sire cattle and their 22 calves using Japanese Black cattle. This new method will contribute to high-throughput genotyping of BoLA-DRB3 by sequence-based typing.

  11. 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

    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

  12. Major histocompatibility complex class II (DRB1*, DQA1*, and DQB1*) and DRB1*04 subtypes' associations of Hashimoto's thyroiditis in a Greek population.

    PubMed

    Kokaraki, G; Daniilidis, M; Yiangou, M; Arsenakis, M; Karyotis, N; Tsilipakou, M; Fleva, A; Gerofotis, A; Karadani, N; Yovos, J G

    2009-03-01

    Hashimoto's thyroiditis (HT) is an autoimmune disease resulting from complex interactions between genetic and environmental factors. The disease is associated with certain human leukocyte antigen (HLA) class II alleles in various populations. We aimed to determine in this study, for the first time in a Greek population, the association of HLA-DRB1*, -DQA1*, and -DQB1* alleles with HT. HLA-DRB1*, -DQA1*, and -DQB1* alleles' and -DRB1*04 subtypes' distribution was evaluated in 125 patients with HT and in 500 healthy control individuals by using a DNA-based sequence-specific primer method. Chi(_)squared tests and Bonferroni correction method were applied in the statistical analysis of the data. Significantly higher frequency of DRB1*04 (24.8% vs 7.7%, P < 0.0001) was observed in HT patients, while HLA-DRB1*07 was significantly decreased (2.8% vs 7.9%, P < 0.05). HLA-DRB1*04 subtyping showed a significant increase of DRB1*0405 (21% vs 7.8%, P < 0.0001) in HT patients. Also significant high frequencies of DQB1*0201 (14.8% vs 8.2%, P < 0.001), DQB1*0302 (18.8% vs 7.0%, P < 0.0001), and DQA1*0301 (25.6% vs 7.8%, P < 0.0001) were recorded in the patient group. Conducting the first research of this kind in a Greek population, our study tries to provide an evaluation of the prevalence of HT relating to HLA-DRB1*0405, and we report a relative risk of 2.7 for HT in a Greek population.

  13. Identification and characterization of the major histocompatibility complex class II DQB (MhcMath-DQB1) alleles in Tibetan macaques (Macaca thibetana).

    PubMed

    Yao, Y-F; Zhao, J-J; Dai, Q-X; Li, J-Y; Zhou, L; Wang, Y-T; Ni, Q-Y; Zhang, M-w; Xu, H-L

    2013-08-01

    Tibetan macaque (Macaca thibetana), an endangered primate species endemic to China, have been used as experimental animal model for various human diseases. Major histocompatibility complex (MHC) genes play a crucial role in the susceptibility and/or resistance to many human diseases, but little is known about Tibetan macaques. To gain an insight into the MHC background and to facilitate the experimental use of Tibetan macaques, the second exon of Mhc-DQB1 gene was sequenced in a cohort of wild Tibetan macaques living in the Sichuan province of China. A total of 23 MhcMath-DQB1 alleles were identified for the first time, illustrating a marked allelic polymorphism at the DQB1 locus for these macaques. Most of the sequences (74%) observed in this study belong to DQB1*06 (9 alleles) and DQB1*18 (8 alleles) lineages, and the rest (26%) belong to DQB1*15 (3 alleles) and DQB1*17 (3 alleles) lineages. The most frequent alleles detected among these macaques were MhcMath-DQB1*15:02:02 (17.9%), followed by Math-DQB1*06:06, 17:03 and 18:01, which were detected in 9 (16.1%) of the monkeys, respectively. Non-synonymous substitutions occurred at a significantly higher frequency than synonymous substitutions in the peptide-binding region, suggesting balancing selection for maintaining polymorphisms at the MHC class II DQB1 locus. Phylogenetic analyses confirms the trans-species model of evolution of the Mhc-DQB1 genes in non-human primates, and in particular, the extensive allele sharing is observed between Tibetan and other macaque species.

  14. Dendritic cells inhibit the progression of Listeria monocytogenes intracellular infection by retaining bacteria in major histocompatibility complex class II-rich phagosomes and by limiting cytosolic growth.

    PubMed

    Westcott, Marlena M; Henry, Curtis J; Amis, Jacqueline E; Hiltbold, Elizabeth M

    2010-07-01

    Dendritic cells (DC) provide a suboptimal niche for the growth of Listeria monocytogenes, a facultative intracellular bacterial pathogen of immunocompromised and pregnant hosts. This is due in part to a failure of large numbers of bacteria to escape to the cytosol, an essential step in the intracellular life cycle that is mediated by listeriolysin O (LLO). Here, we demonstrate that wild-type bacteria that failed to enter the cytosol of bone marrow-derived DC were retained in a LAMP2+ compartment. An isogenic L. monocytogenes strain that produces an LLO protein with reduced pore-forming activity had a severe escape and growth phenotype in DC. Few mutant bacteria entered the cytosol in the first 2 h and were instead found in LAMP2+, major histocompatibility complex class II+ (MHC-II+) H2-DM vesicles characteristic of MHC-II antigen loading compartments (MIIC). In contrast, the mutant had a minor phenotype in bone marrow-derived macrophages (BMM) despite the reduced LLO activity. In the first hour, DC phagosomes acidified to a pH that was, on average, half a point higher than that of BMM phagosomes. Unlike BMM, L. monocytogenes growth in DC was minimal after 5 h, and consequently, DC remained viable and matured late in infection. Taken together, the data are consistent with a model in which phagosomal maturation events associated with the acquisition of MHC-II molecules present a suboptimal environment for L. monocytogenes escape to the DC cytosol, possibly by limiting the activity of LLO. This, in combination with an undefined mechanism that controls bacterial growth late in infection, promotes DC survival during the critical maturation response.

  15. Dendritic Cells Inhibit the Progression of Listeria monocytogenes Intracellular Infection by Retaining Bacteria in Major Histocompatibility Complex Class II-Rich Phagosomes and by Limiting Cytosolic Growth▿ †

    PubMed Central

    Westcott, Marlena M.; Henry, Curtis J.; Amis, Jacqueline E.; Hiltbold, Elizabeth M.

    2010-01-01

    Dendritic cells (DC) provide a suboptimal niche for the growth of Listeria monocytogenes, a facultative intracellular bacterial pathogen of immunocompromised and pregnant hosts. This is due in part to a failure of large numbers of bacteria to escape to the cytosol, an essential step in the intracellular life cycle that is mediated by listeriolysin O (LLO). Here, we demonstrate that wild-type bacteria that failed to enter the cytosol of bone marrow-derived DC were retained in a LAMP2+ compartment. An isogenic L. monocytogenes strain that produces an LLO protein with reduced pore-forming activity had a severe escape and growth phenotype in DC. Few mutant bacteria entered the cytosol in the first 2 h and were instead found in LAMP2+, major histocompatibility complex class II+ (MHC-II+) H2-DM vesicles characteristic of MHC-II antigen loading compartments (MIIC). In contrast, the mutant had a minor phenotype in bone marrow-derived macrophages (BMM) despite the reduced LLO activity. In the first hour, DC phagosomes acidified to a pH that was, on average, half a point higher than that of BMM phagosomes. Unlike BMM, L. monocytogenes growth in DC was minimal after 5 h, and consequently, DC remained viable and matured late in infection. Taken together, the data are consistent with a model in which phagosomal maturation events associated with the acquisition of MHC-II molecules present a suboptimal environment for L. monocytogenes escape to the DC cytosol, possibly by limiting the activity of LLO. This, in combination with an undefined mechanism that controls bacterial growth late in infection, promotes DC survival during the critical maturation response. PMID:20404078

  16. 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

  17. The major histocompatibility complex in monotremes: an analysis of the evolution of Mhc class I genes across all three mammalian subclasses.

    PubMed

    Miska, Katarzyna B; Harrison, Gavan A; Hellman, Lars; Miller, Robert D

    2002-09-01

    We report the isolation and characterization of cDNA clones of expressed, functional major histocompatibility complex class-I ( Mhc-I) genes from two species of monotremes: the duck-billed platypus and the short-beaked echidna. The cDNA clones were isolated from libraries constructed from spleen RNA, clearly establishing their expression in at least this one peripheral lymphoid organ. From the presence of conserved amino acid residues, it appears the expressed sequences encode molecules that likely function as classical Mhc-I. These clones were isolated using monotreme Mhc-I processed pseudogenes as probes. These processed pseudogenes were isolated from genomic DNA and, based on their structure, are likely independently derived in the platypus and echidna. When all the monotreme sequences were included in phylogenetic analyses, we found no apparent orthologous relationships between the platypus and echidna Mhc-I. Analyses that included a large number of Mhc-I sequences from other taxa support a separate monotreme Mhc-I clade, basal to a therian Mhc-I clade that is comprised of sequences from marsupial and placental mammals. The phylogenies also support the hypothesis that Mhc-I genes of placental mammals, marsupials, and monotremes are derived from three separate lineages of Mhc-I genes, best explained by two rounds of duplications and deletions. The first round would have occurred prior to the divergence of monotremes and therians, and the second prior to the divergence of marsupials and placental mammals. The sequences described here represent the first reported functional monotreme Mhc-I, as well as the first processed pseudogenes of any type from monotremes.

  18. 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.

  19. Brucella abortus Inhibits Major Histocompatibility Complex Class II Expression and Antigen Processing through Interleukin-6 Secretion via Toll-Like Receptor 2▿

    PubMed Central

    Barrionuevo, Paula; Cassataro, Juliana; Delpino, M. Victoria; Zwerdling, Astrid; Pasquevich, Karina A.; Samartino, Clara García; Wallach, Jorge C.; Fossati, Carlos A.; Giambartolomei, Guillermo H.

    2008-01-01

    The strategies that allow Brucella abortus to survive inside macrophages for prolonged periods and to avoid the immunological surveillance of major histocompatibility complex class II (MHC-II)-restricted gamma interferon (IFN-γ)-producing CD4+ T lymphocytes are poorly understood. We report here that infection of THP-1 cells with B. abortus inhibited expression of MHC-II molecules and antigen (Ag) processing. Heat-killed B. abortus (HKBA) also induced both these phenomena, indicating the independence of bacterial viability and involvement of a structural component of the bacterium. Accordingly, outer membrane protein 19 (Omp19), a prototypical B. abortus lipoprotein, inhibited both MHC-II expression and Ag processing to the same extent as HKBA. Moreover, a synthetic lipohexapeptide that mimics the structure of the protein lipid moiety also inhibited MHC-II expression, indicating that any Brucella lipoprotein could down-modulate MHC-II expression and Ag processing. Inhibition of MHC-II expression and Ag processing by either HKBA or lipidated Omp19 (L-Omp19) depended on Toll-like receptor 2 and was mediated by interleukin-6. HKBA or L-Omp19 also inhibited MHC-II expression and Ag processing of human monocytes. In addition, exposure to the synthetic lipohexapeptide inhibited Ag-specific T-cell proliferation and IFN-γ production of peripheral blood mononuclear cells from Brucella-infected patients. Together, these results indicate that there is a mechanism by which B. abortus may prevent recognition by T cells to evade host immunity and establish a chronic infection. PMID:17984211

  20. Brucella abortus inhibits major histocompatibility complex class II expression and antigen processing through interleukin-6 secretion via Toll-like receptor 2.

    PubMed

    Barrionuevo, Paula; Cassataro, Juliana; Delpino, M Victoria; Zwerdling, Astrid; Pasquevich, Karina A; García Samartino, Clara; Wallach, Jorge C; Fossati, Carlos A; Giambartolomei, Guillermo H

    2008-01-01

    The strategies that allow Brucella abortus to survive inside macrophages for prolonged periods and to avoid the immunological surveillance of major histocompatibility complex class II (MHC-II)-restricted gamma interferon (IFN-gamma)-producing CD4+ T lymphocytes are poorly understood. We report here that infection of THP-1 cells with B. abortus inhibited expression of MHC-II molecules and antigen (Ag) processing. Heat-killed B. abortus (HKBA) also induced both these phenomena, indicating the independence of bacterial viability and involvement of a structural component of the bacterium. Accordingly, outer membrane protein 19 (Omp19), a prototypical B. abortus lipoprotein, inhibited both MHC-II expression and Ag processing to the same extent as HKBA. Moreover, a synthetic lipohexapeptide that mimics the structure of the protein lipid moiety also inhibited MHC-II expression, indicating that any Brucella lipoprotein could down-modulate MHC-II expression and Ag processing. Inhibition of MHC-II expression and Ag processing by either HKBA or lipidated Omp19 (L-Omp19) depended on Toll-like receptor 2 and was mediated by interleukin-6. HKBA or L-Omp19 also inhibited MHC-II expression and Ag processing of human monocytes. In addition, exposure to the synthetic lipohexapeptide inhibited Ag-specific T-cell proliferation and IFN-gamma production of peripheral blood mononuclear cells from Brucella-infected patients. Together, these results indicate that there is a mechanism by which B. abortus may prevent recognition by T cells to evade host immunity and establish a chronic infection.

  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

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

    2014-02-01

    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.

  2. Up-regulation of major histocompatibility complex class II antigen expression in the central nervous system of dogs with spontaneous canine distemper virus encephalitis.

    PubMed

    Alldinger, S; Wünschmann, A; Baumgärtner, W; Voss, C; Kremmer, E

    1996-09-01

    Major histocompatibility complex class II (MHC II) and canine distemper virus (CDV) antigen expression were compared by immunohistochemistry in the cerebellar white matter of ten dogs with naturally occurring canine distemper encephalitis. In addition, infiltrating mononuclear cells were characterized by employing poly- and monoclonal antibodies directed against human CD3, canine MHC II, CD5, B cell antigen and CDV-specific nucleoprotein. Positive antigen-antibody reaction was visualized by the avidin-biotin-peroxidase complex method on frozen sections. Histologically, neuropathological changes were categorized into acute, subacute, and chronic. In control brains, MHC II expression was weak and predominantly detected on resident microglia of the white matter and on endothelial, perivascular and intravascular cells. In CDV antigen-positive brains, MHC II was mainly found on microglia and to a lesser extent on endothelial, meningeal, choroid plexus epithelial, ependymal and intravascular cells. In addition, virtually all of the perivascular cells expressed MHC II antigen. CDV antigen was demonstrated most frequently in astrocytes. Of the perivascular lymphocytes, the majority were CD3-positive cells, followed by B cells. Only a small proportion of perivascular cells expressed the CD5 antigen. In addition, B cells and CD3 and CD5 antigen-positive cells were found occasionally in subacute and frequently in chronic demyelinating plaques. In acute encephalitis, CDV antigen exhibited a multifocal or diffuse distribution, and MHC II was moderately up-regulated throughout the white matter and accentuated in CDV antigen-positive plaques. In subacute encephalitis, moderate multifocal CDV antigen and moderate to strong diffuse MHC II-specific staining, especially prominent in CDV antigen-positive lesions, were observed. In chronic encephalitis, CDV antigen expression was restricted to single astrocytes at the edge of the lesions or was absent, while MHC II expression

  3. 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

    SciTech Connect

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

    2007-12-01

    The production and crystallization of human leukocyte antigen class II molecules HLA-DQ2 and HLA-DQ8 in complex with deamidated gliadin peptides is reported. Crystals of HLA-DQ2{sup PQPELPYPQ} diffracted to 3.9 Å, while the HLA-DQ8{sup EGSFQPSQE} crystals diffracted to 2.1 Å, allowing structure determination by molecular replacement. 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{sup +} 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.

  4. The life span of major histocompatibility complex-peptide complexes influences the efficiency of presentation and immunogenicity of two class I-restricted cytotoxic T lymphocyte epitopes in the Epstein-Barr virus nuclear antigen 4

    PubMed Central

    1996-01-01

    -containing complexes. This difference in persistence is likely to determine the representation of individual class I-restricted CTL epitopes within the cell surface pool of molecules, and may be an important factor contributing to their immunogenicity. PMID:8642295

  5. Cutting Classes

    ERIC Educational Resources Information Center

    Hacker, Andrew

    1976-01-01

    Provides critical reviews of three books, "The Political Economy of Social Class", "Ethnicity: Theory and Experience," and "Ethnicity in the United States," focusing on the political economy of social class and ethnicity. (Author/AM)

  6. Dissection of the interaction of the human cytomegalovirus-derived US2 protein with major histocompatibility complex class I molecules: prominent role of a single arginine residue in human leukocyte antigen-A2.

    PubMed

    Thilo, Claudia; Berglund, Peter; Applequist, Steven E; Yewdell, Jonathan W; Ljunggren, Hans-Gustaf; Achour, Adnane

    2006-03-31

    Human cytomegalovirus encodes several proteins that interfere with expression of major histocompatibility complex (MHC) class I molecules on the surface of infected cells. The unique short protein 2 (US2) binds to many MHC class I allomorphs in the endoplasmic reticulum, preventing cell surface expression of the class I molecule in question. The molecular interactions underlying US2 binding to MHC class I molecules and its allele specificity have not been fully clarified. In the present study, we first compared the sequences and the structures of US2 retained versus non-retained human leukocyte antigen (HLA) class I allomorphs to identify MHC residues of potential importance for US2 binding. On the basis of this analysis, 18 individual HLA-A2 mutants were generated and the ability of full-length US2 to bind wild-type and mutated HLA-A2 complexes was assessed. We demonstrate that Arg181 plays a critical role in US2-mediated inhibition of HLA-A2 cell surface expression. The structural comparison of all known crystal structures of HLA-A2 either alone, or in complex with T cell receptor or the CD8 co-receptor, indicates that binding of US2 to HLA-A2 results in a unique, large conformational change of the side chain of Arg181. However, although the presence of Arg181 seems to be a prerequisite for US2 binding to HLA-A2, it is not sufficient for binding to all MHC class I alleles.

  7. Class Size.

    ERIC Educational Resources Information Center

    Underwood, Siobhan; Lumsden, Linda S.

    1994-01-01

    The items featured in this annotated bibliography touch on several aspects of the multifaceted class-size debate. Allen Odden reviews the literature and contends that class-size reduction should be used "sparingly and strategically." C. M. Achilles and colleagues examines two different class-size situations and find student test…

  8. Class Matters

    ERIC Educational Resources Information Center

    Valdata, Patricia

    2005-01-01

    Ever since George Washington opted for the title of president rather than king, Americans have been uncomfortable with the idea of class distinctions. This article presents an interview with Dr. Janet Galligani Casey regarding the idea of class distinctions. Galligani Casey, who grew up in a working-class neighborhood in Somerville, Massachusetts,…

  9. The Effect of Class II Major Histocompatibility Complex Expression on Adherence of Helicobacter pylori and Induction of Apoptosis in Gastric Epithelial Cells: A Mechanism for T Helper Cell Type 1–mediated Damage

    PubMed Central

    Fan, Xuejun; Crowe, Sheila E.; Behar, Simon; Gunasena, Harshani; Ye, Gang; Haeberle, Helene; Van Houten, Nancy; Gourley, William K.; Ernst, Peter B.; Reyes, Victor E.

    1998-01-01

    Helicobacter pylori infection is associated with gastric epithelial damage, including apoptosis, ulceration, and cancer. Although bacterial factors and the host response are believed to contribute to gastric disease, no receptor has been identified that explains how the bacteria attach and signal the host cell to undergo apoptosis. Using H. pylori as “bait” to capture receptor proteins in solubilized membranes of gastric epithelial cells, class II major histocompatibility complex (MHC) molecules were identified as a possible receptor. Signaling through class II MHC molecules leading to the induction of apoptosis was confirmed using cross-linking IgM antibodies to surface class II MHC molecules. Moreover, binding of H. pylori and the induction of apoptosis were inhibited by antibodies recognizing class II MHC. Since type 1 T helper cells are present during infection and produce interferon (IFN)-γ, which increases class II MHC expression, gastric epithelial cell lines were exposed to H. pylori in the presence or absence of IFN-γ. IFN-γ increased the attachment of the bacteria as well as the induction of apoptosis in gastric epithelial cells. In contrast to MHC II–negative cell lines, H. pylori induced apoptosis in cells expressing class II MHC molecules constitutively or after gene transfection. These data describe a novel receptor for H. pylori and provide a mechanism by which bacteria and the host response interact in the pathogenesis of gastric epithelial cell damage. PMID:9584144

  10. Early detection of dominant Env-specific and subdominant Gag-specific CD8+ lymphocytes in equine infectious anemia virus-infected horses using major histocompatibility complex class I/peptide tetrameric complexes

    PubMed Central

    Mealey, Robert H.; Sharif, Amin; Ellis, Shirley A.; Littke, Matt H.; Leib, Steven R.; McGuire, Travis C.

    2012-01-01

    Cytotoxic T lymphocytes (CTL) are critical for control of lentiviruses, including equine infectious anemia virus (EIAV). Measurement of equine CTL responses has relied on chromium-release assays, which do not allow accurate quantitation. Recently, the equine MHC class I molecule 7-6, associated with the ELA-A1 haplotype, was shown to present both the Gag-GW12 and Env-RW12 EIAV CTL epitopes. In this study, 7-6/Gag-GW12 and 7-6/Env-RW12 MHC class I/peptide tetrameric complexes were constructed and used to analyze Gag-GW12- and Env-RW12-specific CTL responses in two EIAV-infected horses (A2164 and A2171). Gag-GW12 and Env-RW12 tetramer-positive CD8+ cells were identified in nonstimulated peripheral blood mononuclear cells as early as 14 days post-EIAV inoculation, and frequencies of tetramer-positive cells ranged from 0.4% to 6.7% of nonstimulated peripheral blood CD8+ cells during the 127-day study period. Although both horses terminated the initial viremic peak, only horse A2171 effectively controlled viral load. Neutralizing antibody was present during the initial control of viral load in both horses, but the ability to maintain control correlated with Gag-GW12-specific CD8+ cells in A2171. Despite Env-RW12 dominance, Env-RW12 escape viral variants were identified in both horses and there was no correlation between Env-RW12-specific CD8+ cells and control of viral load. Although Gag-GW12 CTL escape did not occur, a Gag-GW12 epitope variant arose in A2164 that was recognized less efficiently than the original epitope. These data indicate that tetramers are useful for identification and quantitation of CTL responses in horses, and suggest that the observed control of EIAV replication and clinical disease was associated with sustained CTL recognition of Gag-specific epitopes. PMID:15979679

  11. Early detection of dominant Env-specific and subdominant Gag-specific CD8+ lymphocytes in equine infectious anemia virus-infected horses using major histocompatibility complex class I/peptide tetrameric complexes.

    PubMed

    Mealey, Robert H; Sharif, Amin; Ellis, Shirley A; Littke, Matt H; Leib, Steven R; McGuire, Travis C

    2005-08-15

    Cytotoxic T lymphocytes (CTL) are critical for control of lentiviruses, including equine infectious anemia virus (EIAV). Measurement of equine CTL responses has relied on chromium-release assays, which do not allow accurate quantitation. Recently, the equine MHC class I molecule 7-6, associated with the ELA-A1 haplotype, was shown to present both the Gag-GW12 and Env-RW12 EIAV CTL epitopes. In this study, 7-6/Gag-GW12 and 7-6/Env-RW12 MHC class I/peptide tetrameric complexes were constructed and used to analyze Gag-GW12- and Env-RW12-specific CTL responses in two EIAV-infected horses (A2164 and A2171). Gag-GW12 and Env-RW12 tetramer-positive CD8+ cells were identified in nonstimulated peripheral blood mononuclear cells as early as 14 days post-EIAV inoculation, and frequencies of tetramer-positive cells ranged from 0.4% to 6.7% of nonstimulated peripheral blood CD8+ cells during the 127-day study period. Although both horses terminated the initial viremic peak, only horse A2171 effectively controlled viral load. Neutralizing antibody was present during the initial control of viral load in both horses, but the ability to maintain control correlated with Gag-GW12-specific CD8+ cells in A2171. Despite Env-RW12 dominance, Env-RW12 escape viral variants were identified in both horses and there was no correlation between Env-RW12-specific CD8+ cells and control of viral load. Although Gag-GW12 CTL escape did not occur, a Gag-GW12 epitope variant arose in A2164 that was recognized less efficiently than the original epitope. These data indicate that tetramers are useful for identification and quantitation of CTL responses in horses, and suggest that the observed control of EIAV replication and clinical disease was associated with sustained CTL recognition of Gag-specific epitopes.

  12. Rapid assignment of the swine major histocompatibility complex (SLA) class I and II genotypes in Clawn miniature swine using PCR-SSP and PCR-RFLP methods.

    PubMed

    Ando, Asako; Ota, Masao; Sada, Masaharu; Katsuyama, Yoshihiko; Goto, Rieko; Shigenari, Atsuko; Kawata, Hisako; Anzai, Tatsuya; Iwanaga, Takahiro; Miyoshi, Yukari; Fujimura, Nobuyuki; Inoko, Hidetoshi

    2005-03-01

    Inbred miniature swine with defined novel SLA haplotypes will be useful in allo- and xeno-transplantation studies, which can be carried out representing variable combinations of SLA haplotypes. In Clawn miniature swine, two haplotypes (c1 and c2) and one crossover haplotype (c3) have been assigned by nucleotide sequence determination of RT-PCR products of the three SLA classical class I genes and two SLA class II genes. To select SLA class I and II homozygotes in Clawn miniature swine individuals, we developed a rapid and simple SLA-class I- and II-DNA typing method by a combination of polymerase chain reaction-sequence specific primer (PCR-SSP) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques. Seven allele specific primer pairs were designed for amplification of the second exons of three SLA class I genes, SLA-1, SLA-2, and SLA-3, and one SLA class II gene, DRB1. Furthermore, based on PCR-RFLP patterns in the SLA-DQB1 gene, two allelic variants were recognized in the second exon in the Clawn miniature swine. Three haplotypes, c1, c2 and c3, were simply identified by the combination of PCR-SSP and PCR-RFLP methods in 22 samples from five families. A single allele at each of the class I and II genes was also observed in seven samples as SLA class I and II homozygotes with either the c1 or c2 haplotype. The combination of PCR-SSP and PCR-RFLP methods facilitate the rapid identification of the three haplotypes and SLA class I and II homozygotes in individual Clawn miniature swine.

  13. Major histocompatibility complex (MHC) class I and II alleles which confer susceptibility or protection in the Morphea in Adults and Children (MAC) cohort

    PubMed Central

    Jacobe, Heidi; Ahn, Chul; Arnett, Frank; Reveille, John D.

    2014-01-01

    Objective To determine human leukocyte antigen class I (HLA-class I) and II (HLA-class II) alleles associated with morphea (localized scleroderma) in the Morphea in Adults and Children (MAC) cohort by a nested case–control association study. Methods Morphea patients were included from MAC cohort and matched controls from the NIH/NIAMS Scleroderma Family Registry and DNA Repository and Division of Rheumatology at the University of Texas Health Science Center at Houston. HLA- Class II genotyping and SSCP typing was performed of HLA-A, -B, -C alleles. Associations between HLA-Class I and II alleles and morphea as well as its subphenotypes were determined. Results There were 211 cases available for HLA-class I typing with 726 matched controls and 158 cases available for HLA Class-II typing with 1108 matched controls. The strongest associations were found with DRB1*04:04 (OR 2.3, 95% CI 1.4–4.0 P=0.002) and HLA-B*37 conferred the highest OR among Class I alleles (3.3, 95% CI 1.6–6.9, P= 0.0016). Comparison with risk alleles in systemic sclerosis determined using the same methods and control population revealed one common allele (DRB*04:04). Conclusion Results of the present study demonstrate specific HLA Class I and II alleles are associated with morphea and likely generalized and linear subtypes. The associated morphea alleles are different than in scleroderma, implicating morphea is also immunogenetically distinct. Risk alleles in morphea are also associated with conditions such as rheumatoid arthritis (RA) and other autoimmune conditions. Population based studies indicate patients with RA have increased risk of morphea, implicating a common susceptibility allele. PMID:25223600

  14. Genetics and social class

    PubMed Central

    Holtzman, N

    2002-01-01

    Design: Using genetic epidemiological principles, five claims on the role of genes in determining social class are examined: (1) traits that run in families are usually inherited; (2) complex traits can be explained by alleles at a single gene locus; (3) complex traits are transmitted intact from one generation to the next; (4) natural selection explains social advantage. (5) Heritability estimates provide a valid estimate of the importance of genes in explaining complex human traits or behaviour. Results: (1) Traits that run in families can result from environmental exposures that differ by social class. (2) The protein encoded by any single gene has too narrow a range of biological activity to explain traits as complex as social status. (3) Because alleles at different gene loci are transmitted independently, genetic inheritance cannot explain why offspring display the same complex traits as their parents. (4) The propagation of mutations that might result in a selective advantage takes much longer than the time for which any social class has achieved or maintained dominance. (5) Heritability measures are accurate only when environment is maintained constant. This is impossible in evaluating human traits. Conclusions: The roots of social class differences do not lie in our genes. Consequently, genetics cannot be used as a justification for maintaining a ruling class, limiting procreation among the poor, or minimising social support programmes. PMID:12080161

  15. Varicella-Zoster Virus Downregulates Programmed Death Ligand 1 and Major Histocompatibility Complex Class I in Human Brain Vascular Adventitial Fibroblasts, Perineurial Cells, and Lung Fibroblasts

    PubMed Central

    Jones, Dallas; Blackmon, Anna; Neff, C. Preston; Palmer, Brent E.; Gilden, Don; Badani, Hussain

    2016-01-01

    ABSTRACT Varicella-zoster virus (VZV) vasculopathy produces stroke, giant cell arteritis, and granulomatous aortitis, and it develops after virus reactivates from ganglia and spreads transaxonally to arterial adventitia, resulting in persistent inflammation and pathological vascular remodeling. The mechanism(s) by which inflammatory cells persist in VZV-infected arteries is unknown; however, virus-induced dysregulation of programmed death ligand 1 (PD-L1) may play a role. Specifically, PD-L1 can be expressed on virtually all nucleated cells and suppresses the immune system by interacting with the programmed cell death protein receptor 1, found exclusively on immune cells; thus, downregulation of PD-L1 may promote inflammation, as seen in some autoimmune diseases. Both flow cytometry and immunofluorescence analyses to test whether VZV infection of adventitial cells downregulates PD-L1 showed decreased PD-L1 expression in VZV-infected compared to mock-infected human brain vascular adventitial fibroblasts (HBVAFs), perineural cells (HPNCs), and fetal lung fibroblasts (HFLs) at 72 h postinfection. Quantitative RT-PCR analyses showed no change in PD-L1 transcript levels between mock- and VZV-infected cells, indicating a posttranscriptional mechanism for VZV-mediated downregulation of PD-L1. Flow cytometry analyses showed decreased major histocompatibility complex class I (MHC-I) expression in VZV-infected cells and adjacent uninfected cells compared to mock-infected cells. These data suggest that reduced PD-L1 expression in VZV-infected adventitial cells contribute to persistent vascular inflammation observed in virus-infected arteries from patients with VZV vasculopathy, while downregulation of MHC-I prevents viral clearance. IMPORTANCE Here, we provide the first demonstration that VZV downregulates PD-L1 expression in infected HBVAFs, HPNCs, and HFLs, which, together with the noted VZV-mediated downregulation of MHC-I, might foster persistent inflammation in vessels

  16. Comprehensive Analysis of Contributions from Protein Conformational Stability and Major Histocompatibility Complex Class II-Peptide Binding Affinity to CD4+ Epitope Immunogenicity in HIV-1 Envelope Glycoprotein

    PubMed Central

    Li, Tingfeng; Steede, N. Kalaya; Nguyen, Hong-Nam P.; Freytag, Lucy C.; McLachlan, James B.; Mettu, Ramgopal R.; Robinson, James E.

    2014-01-01

    ABSTRACT Helper T-cell epitope dominance in human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 is not adequately explained by peptide binding to major histocompatibility complex (MHC) proteins. Antigen processing potentially influences epitope dominance, but few, if any, studies have attempted to reconcile the influences of antigen processing and MHC protein binding for all helper T-cell epitopes of an antigen. Epitopes of gp120 identified in both humans and mice occur on the C-terminal flanks of flexible segments that are likely to be proteolytic cleavage sites. In this study, the influence of gp120 conformation on the dominance pattern in gp120 from HIV strain 89.6 was examined in CBA mice, whose MHC class II protein has one of the most well defined peptide-binding preferences. Only one of six dominant epitopes contained the most conserved element of the I-Ak binding motif, an aspartic acid. Destabilization of the gp120 conformation by deletion of single disulfide bonds preferentially enhanced responses to the cryptic I-Ak motif-containing sequences, as reported by T-cell proliferation or cytokine secretion. Conversely, inclusion of CpG in the adjuvant with gp120 enhanced responses to the dominant CD4+ T-cell epitopes. The gp120 destabilization affected secretion of some cytokines more than others, suggesting that antigen conformation could modulate T-cell functions through mechanisms of antigen processing. IMPORTANCE CD4+ helper T cells play an essential role in protection against HIV and other pathogens. Thus, the sites of helper T-cell recognition, the dominant epitopes, are targets for vaccine design; and the corresponding T cells may provide markers for monitoring infection and immunity. However, T-cell epitopes are difficult to identify and predict. It is also unclear whether CD4+ T cells specific for one epitope are more protective than T cells specific for other epitopes. This work shows that the three-dimensional (3D) structure of an

  17. Varicella-Zoster Virus Downregulates Programmed Death Ligand 1 and Major Histocompatibility Complex Class I in Human Brain Vascular Adventitial Fibroblasts, Perineurial Cells, and Lung Fibroblasts.

    PubMed

    Jones, Dallas; Blackmon, Anna; Neff, C Preston; Palmer, Brent E; Gilden, Don; Badani, Hussain; Nagel, Maria A

    2016-12-01

    Varicella-zoster virus (VZV) vasculopathy produces stroke, giant cell arteritis, and granulomatous aortitis, and it develops after virus reactivates from ganglia and spreads transaxonally to arterial adventitia, resulting in persistent inflammation and pathological vascular remodeling. The mechanism(s) by which inflammatory cells persist in VZV-infected arteries is unknown; however, virus-induced dysregulation of programmed death ligand 1 (PD-L1) may play a role. Specifically, PD-L1 can be expressed on virtually all nucleated cells and suppresses the immune system by interacting with the programmed cell death protein receptor 1, found exclusively on immune cells; thus, downregulation of PD-L1 may promote inflammation, as seen in some autoimmune diseases. Both flow cytometry and immunofluorescence analyses to test whether VZV infection of adventitial cells downregulates PD-L1 showed decreased PD-L1 expression in VZV-infected compared to mock-infected human brain vascular adventitial fibroblasts (HBVAFs), perineural cells (HPNCs), and fetal lung fibroblasts (HFLs) at 72 h postinfection. Quantitative RT-PCR analyses showed no change in PD-L1 transcript levels between mock- and VZV-infected cells, indicating a posttranscriptional mechanism for VZV-mediated downregulation of PD-L1. Flow cytometry analyses showed decreased major histocompatibility complex class I (MHC-I) expression in VZV-infected cells and adjacent uninfected cells compared to mock-infected cells. These data suggest that reduced PD-L1 expression in VZV-infected adventitial cells contribute to persistent vascular inflammation observed in virus-infected arteries from patients with VZV vasculopathy, while downregulation of MHC-I prevents viral clearance. Here, we provide the first demonstration that VZV downregulates PD-L1 expression in infected HBVAFs, HPNCs, and HFLs, which, together with the noted VZV-mediated downregulation of MHC-I, might foster persistent inflammation in vessels, leading to

  18. Association analysis of the major histocompatibility complex, class II, DQ β1 gene, HLA-DQB1, with narcolepsy in Han Chinese patients from Taiwan.

    PubMed

    Chen, Yun-Hsiang; Huang, Yu-Shu; Chien, Wei-Hsien; Chen, Chia-Hsiang

    2013-12-01

    Narcolepsy is a rare, chronic, disabling neuropsychiatric disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, sleep paralysis, and abnormal rapid eye movement sleep. It is strongly associated with the HLA-DQB1(∗)06:02 allele in various ethnic groups. Our study aimed to investigate the allelic spectrum of HLA-DQB1 in a sample of Han Chinese patients with narcolepsy and control subjects from Taiwan. We determined the genotype of the major histocompatibility complex, class II, DQ β1 gene, HLA-DQB1, in 72 narcolepsy subjects (44 men, 28 women), including 52 narcolepsy subjects with cataplexy (narcolepsy+cataplexy), 20 narcolepsy subjects without cataplexy (narcolepsy-cataplexy), and 194 control subjects (94 men, 100 women) using a sequence-specific oligonucleotide-probe hybridization technique. We found a strong HLA-DQB1(∗)06:02 association in narcolepsy+cataplexy subjects (odds ratio [OR], 321.4 [95% confidence interval {CI}, 70.7-1461.4]). The association was less prominent in narcolepsy-cataplexy subjects (OR, 6.9 [95% CI, 2.4-20.1]). In addition to the DQB1(∗)06:02, we found that (∗)03:01 also was a predisposing allele (OR, 2.0 [95% CI, 1.1-3.7]) in narcolepsy+cataplexy subjects, though the (∗)06:01 was a predisposing allele (OR, 2.8 [95% CI, 1.2-6.7]) in narcolepsy-cataplexy subjects. Furthermore, we found a significant overrepresentation of DQB1(∗)06:02 homozygotes in narcolepsy+cataplexy subjects. Our data add further support to the strong association of the HLA-DQB1(∗)06:02 allele with narcolepsy, especially in narcolepsy+cataplexy patients. Our study also indicates additional HLA-DQB1 alleles may modify the presentation of narcolepsy+cataplexy patients, such as DQB1(∗)03:01 and DQB1(∗)06:01 in our study. Our results are limited by the small sample size and can only be considered as preliminary findings. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Recognition of the Major Histocompatibility Complex (MHC) Class Ib Molecule H2-Q10 by the Natural Killer Cell Receptor Ly49C.

    PubMed

    Sullivan, Lucy C; Berry, Richard; Sosnin, Natasha; Widjaja, Jacqueline M L; Deuss, Felix A; Balaji, Gautham R; LaGruta, Nicole L; Mirams, Michiko; Trapani, Joseph A; Rossjohn, Jamie; Brooks, Andrew G; Andrews, Daniel M

    2016-09-02

    Murine natural killer (NK) cells are regulated by the interaction of Ly49 receptors with major histocompatibility complex class I molecules (MHC-I). Although the ligands for inhibitory Ly49 were considered to be restricted to classical MHC (MHC-Ia), we have shown that the non-classical MHC molecule (MHC-Ib) H2-M3 was a ligand for the inhibitory Ly49A. Here we establish that another MHC-Ib, H2-Q10, is a bona fide ligand for the inhibitory Ly49C receptor. H2-Q10 bound to Ly49C with a marginally lower affinity (∼5 μm) than that observed between Ly49C and MHC-Ia (H-2K(b)/H-2D(d), both ∼1 μm), and this recognition could be prevented by cis interactions with H-2K in situ To understand the molecular details underpinning Ly49·MHC-Ib recognition, we determined the crystal structures of H2-Q10 and Ly49C bound H2-Q10. Unliganded H2-Q10 adopted a classical MHC-I fold and possessed a peptide-binding groove that exhibited features similar to those found in MHC-Ia, explaining the diverse peptide binding repertoire of H2-Q10. Ly49C bound to H2-Q10 underneath the peptide binding platform to a region that encompassed residues from the α1, α2, and α3 domains, as well as the associated β2-microglobulin subunit. This docking mode was conserved with that previously observed for Ly49C·H-2K(b) Indeed, structure-guided mutation of Ly49C indicated that Ly49C·H2-Q10 and Ly49C·H-2K(b) possess similar energetic footprints focused around residues located within the Ly49C β4-stand and L5 loop, which contact the underside of the peptide-binding platform floor. Our data provide a structural basis for Ly49·MHC-Ib recognition and demonstrate that MHC-Ib represent an extended family of ligands for Ly49 molecules.

  20. Major Histocompatibility Complex Class II HLA-DRα Is Downregulated by Kaposi's Sarcoma-Associated Herpesvirus-Encoded Lytic Transactivator RTA and MARCH8

    PubMed Central

    Sun, Zhiguo; Jha, Hem Chandra; Pei, Yong-gang

    2016-01-01

    ABSTRACT Kaposi's sarcoma-associated herpesvirus (KSHV) maintains two modes of life cycle, the latent and lytic phases. To evade the attack of the cell host's immune system, KSHV switches from the lytic to the latent phase, a phase in which only a few of viral proteins are expressed. The mechanism by which KSHV evades the attack of the immune system and establishes latency has not been fully understood. Major histocompatibility complex class II (MHC-II) molecules are key components of the immune system defense mechanism against viral infections. Here we report that HLA-DRα, a member of the MHC-II molecules, was downregulated by the replication and transcription activator (RTA) protein encoded by KSHV ORF50, an important regulator of the viral life cycle. RTA not only downregulated HLA-DRα at the protein level through direct binding and degradation through the proteasome pathway but also indirectly downregulated the protein level of HLA-DRα by enhancing the expression of MARCH8, a member of the membrane-associated RING-CH (MARCH) proteins. Our findings indicate that KSHV RTA facilitates evasion of the virus from the immune system through manipulation of HLA-DRα. IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) has a causal role in a number of human cancers, and its persistence in infected cells is controlled by the host's immune system. The mechanism by which KSHV evades an attack by the immune system has not been well understood. This work represents studies which identify a novel mechanism by which the virus can facilitate evasion of an immune system. We now show that RTA, the replication and transcription activator encoded by KSHV (ORF50), can function as an E3 ligase to degrade HLA-DRα. It can directly bind and induce degradation of HLA-DRα through the ubiquitin-proteasome degradation pathway. In addition to the direct regulation of HLA-DRα, RTA can also indirectly downregulate the level of HLA-DRα protein by upregulating transcription of MARCH8

  1. Dynamics of the Major Histocompatibility Complex Class I Processing and Presentation Pathway in the Course of Malaria Parasite Development in Human Hepatocytes: Implications for Vaccine Development

    PubMed Central

    Ma, Jinxia; Trop, Stefanie; Baer, Samantha; Rakhmanaliev, Elian; Arany, Zita; Dumoulin, Peter; Zhang, Hao; Romano, Julia; Coppens, Isabelle; Levitsky, Victor; Levitskaya, Jelena

    2013-01-01

    Control of parasite replication exerted by MHC class I restricted CD8+ T-cells in the liver is critical for vaccination-induced protection against malaria. While many intracellular pathogens subvert the MHC class I presentation machinery, its functionality in the course of malaria replication in hepatocytes has not been characterized. Using experimental systems based on specific identification, isolation and analysis of human hepatocytes infected with P. berghei ANKA GFP or P. falciparum 3D7 GFP sporozoites we demonstrated that molecular components of the MHC class I pathway exhibit largely unaltered expression in malaria-infected hepatocytes until very late stages of parasite development. Furthermore, infected cells showed no obvious defects in their capacity to upregulate expression of different molecular components of the MHC class I machinery in response to pro-inflammatory lymphokines or trigger direct activation of allo-specific or peptide-specific human CD8+ T-cells. We further demonstrate that ectopic expression of circumsporozoite protein does not alter expression of critical genes of the MHC class I pathway and its response to pro-inflammatory cytokines. In addition, we identified supra-cellular structures, which arose at late stages of parasite replication, possessed the characteristic morphology of merosomes and exhibited nearly complete loss of surface MHC class I expression. These data have multiple implications for our understanding of natural T-cell immunity against malaria and may promote development of novel, efficient anti-malaria vaccines overcoming immune escape of the parasite in the liver. PMID:24086507

  2. Structural analysis of the human interferon gamma receptor: a small segment of the intracellular domain is specifically required for class I major histocompatibility complex antigen induction and antiviral activity.

    PubMed

    Cook, J R; Jung, V; Schwartz, B; Wang, P; Pestka, S

    1992-12-01

    Mutations of the human interferon gamma (IFN-gamma) receptor intracellular domain have permitted us to define a restricted region of that domain as necessary for both induction of class I major histocompatibility complex antigen by IFN-gamma and protection against encephalomyocarditis virus. This region consists of five amino acids (YDKPH), all of which are conserved in the human and murine receptors. Tyr-457 and His-461 are essential for activity. Approximately 80% of the amino acids of the intracellular domain of the receptor is not required for major histocompatibility complex class I antigen induction or for antiviral protection against encephalomyocarditis virus. The observation that there was no protection by IFN-gamma against vesiculostomatitis virus indicates that other factors, in addition to chromosome 21 accessory factor(s), are required to generate the full complement of transduction signals from the human IFN-gamma receptor.

  3. The seirena B class floral homeotic mutant of California Poppy (Eschscholzia californica) reveals a function of the enigmatic PI motif in the formation of specific multimeric MADS domain protein complexes.

    PubMed

    Lange, Matthias; Orashakova, Svetlana; Lange, Sabrina; Melzer, Rainer; Theißen, Günter; Smyth, David R; Becker, Annette

    2013-02-01

    The products of B class floral homeotic genes specify petal and stamen identity, and loss of B function results in homeotic conversions of petals into sepals and s