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Horstmann N, Tran CN, Brumlow C, DebRoy S, Yao H, Nogueras Gonzalez G, Makthal N, Kumaraswami M, Shelburne SA. Phosphatase activity of the control of virulence sensor kinase CovS is critical for the pathogenesis of group A streptococcus. PLoS Pathog 2018; 14:e1007354. [PMID: 30379939 PMCID: PMC6231683 DOI: 10.1371/journal.ppat.1007354] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 11/12/2018] [Accepted: 09/14/2018] [Indexed: 12/15/2022] Open
Abstract
The control of virulence regulator/sensor kinase (CovRS) two-component system is critical to the infectivity of group A streptococcus (GAS), and CovRS inactivating mutations are frequently observed in GAS strains causing severe human infections. CovS modulates the phosphorylation status and with it the regulatory effect of its cognate regulator CovR via its kinase and phosphatase activity. However, the contribution of each aspect of CovS function to GAS pathogenesis is unknown. We created isoallelic GAS strains that differ only by defined mutations which either abrogate CovR phosphorylation, CovS kinase or CovS phosphatase activity in order to test the contribution of CovR phosphorylation levels to GAS virulence, emergence of hypervirulent CovS-inactivated strains during infection, and GAS global gene expression. These sets of strains were created in both serotype M1 and M3 backgrounds, two prevalent GAS disease-causing serotypes, to ascertain whether our observations were serotype-specific. In both serotypes, GAS strains lacking CovS phosphatase activity (CovS-T284A) were profoundly impaired in their ability to cause skin infection or colonize the oropharynx in mice and to survive neutrophil killing in human blood. Further, response to the human cathelicidin LL-37 was abrogated. Hypervirulent GAS isolates harboring inactivating CovRS mutations were not recovered from mice infected with M1 strain M1-CovS-T284A and only sparsely recovered from mice infected with M3 strain M3-CovS-T284A late in the infection course. Consistent with our virulence data, transcriptome analyses revealed increased repression of a broad array of virulence genes in the CovS phosphatase deficient strains, including the genes encoding the key anti-phagocytic M protein and its positive regulator Mga, which are not typically part of the CovRS transcriptome. Taken together, these data establish a key role for CovS phosphatase activity in GAS pathogenesis and suggest that CovS phosphatase activity could be a promising therapeutic target in GAS without promoting emergence of hypervirulent CovS-inactivated strains. Group A streptococcus (GAS), also known as Streptococcus pyogenes, causes a broad array of human infections of varying severity. Tight control of production of virulence factors is critical to GAS pathogenesis, and the control of virulence two-component signaling system (CovRS) is central to this process. The activity of the bifunctional histidine kinase CovS determines the phosphorylation status and thereby the activity of its cognate response regulator CovR. Herein, we sought to determine how varying CovR phosphorylation level (CovR~P) impacts GAS pathophysiology. Using three infection models, we discovered that GAS strains lacking CovS phosphatase activity resulting in high CovR~P levels had markedly impaired infectivity. Transcriptome analysis revealed that the hypovirulent phenotype of CovS phosphatase deficient strains is due to down-regulation of numerous genes encoding GAS virulence factors. We identified repression of additional virulence genes that are typically not controlled by CovR, thus expanding the CovR regulon at high CovR~P concentrations. Our data indicate that phosphatase activity of CovS sensor kinase is crucial for spatiotemporal regulation of GAS virulence gene expression. Thus, we propose that targeting the phosphatase activity of CovS sensor kinase could be a promising novel therapeutic approach to combat GAS disease.
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Affiliation(s)
- Nicola Horstmann
- Department of Infectious Diseases, Infection Control and Employee Health, MD Anderson Cancer Center, Houston TX, United States of America
| | - Chau Nguyen Tran
- Department of Infectious Diseases, Infection Control and Employee Health, MD Anderson Cancer Center, Houston TX, United States of America
| | - Chelcy Brumlow
- Department of Infectious Diseases, Infection Control and Employee Health, MD Anderson Cancer Center, Houston TX, United States of America
| | - Sruti DebRoy
- Department of Infectious Diseases, Infection Control and Employee Health, MD Anderson Cancer Center, Houston TX, United States of America
| | - Hui Yao
- Department of Bioinformatics and Computational Biology, MD Anderson Cancer Center, Houston TX, United States of America
| | - Graciela Nogueras Gonzalez
- Department of Bioinformatics and Computational Biology, MD Anderson Cancer Center, Houston TX, United States of America
| | - Nishanth Makthal
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, United States of America
| | - Muthiah Kumaraswami
- Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, TX, United States of America
| | - Samuel A. Shelburne
- Department of Infectious Diseases, Infection Control and Employee Health, MD Anderson Cancer Center, Houston TX, United States of America
- Department of Genomic Medicine, MD Anderson Cancer Center, Houston TX, United States of America
- * E-mail:
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Rac J, Haas F, Schumacher A, Middeldorp JM, Delecluse HJ, Speck RF, Bernasconi M, Nadal D. Telomerase activity impacts on Epstein-Barr virus infection of AGS cells. PLoS One 2015; 10:e0123645. [PMID: 25856387 PMCID: PMC4391831 DOI: 10.1371/journal.pone.0123645] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 02/26/2015] [Indexed: 01/09/2023] Open
Abstract
The Epstein-Barr virus (EBV) is transmitted from host-to-host via saliva and is associated with epithelial malignancies including nasopharyngeal carcinoma (NPC) and some forms of gastric carcinoma (GC). Nevertheless, EBV does not transform epithelial cells in vitro where it is rapidly lost from infected primary epithelial cells or epithelial tumor cells. Long-term infection by EBV, however, can be established in hTERT-immortalized nasopharyngeal epithelial cells. Here, we hypothesized that increased telomerase activity in epithelial cells enhances their susceptibility to infection by EBV. Using HONE-1, AGS and HEK293 cells we generated epithelial model cell lines with increased or suppressed telomerase activity by stable ectopic expression of hTERT or of a catalytically inactive, dominant negative hTERT mutant. Infection experiments with recombinant prototypic EBV (rB95.8), recombinant NPC EBV (rM81) with increased epithelial cell tropism compared to B95.8, or recombinant B95.8 EBV with BZLF1-knockout that is not able to undergo lytic replication, revealed that infection frequencies positively correlate with telomerase activity in AGS cells but also partly depend on the cellular background. AGS cells with increased telomerase activity showed increased expression mainly of latent EBV genes, suggesting that increased telomerase activity directly acts on the EBV infection of epithelial cells by facilitating latent EBV gene expression early upon virus inoculation. Thus, our results indicate that infection of epithelial cells by EBV is a very selective process involving, among others, telomerase activity and cellular background to allow for optimized host-to-host transmission via saliva.
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Affiliation(s)
- Jürgen Rac
- Experimental Infectious Diseases and Cancer Research, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Children’s Research Center, University Children’s Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Florian Haas
- Experimental Infectious Diseases and Cancer Research, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Children’s Research Center, University Children’s Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Andrina Schumacher
- Experimental Infectious Diseases and Cancer Research, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Children’s Research Center, University Children’s Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Jaap M. Middeldorp
- Department of Pathology and Cancer Center Amsterdam, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
| | - Henri-Jacques Delecluse
- Division of Pathogenesis of Virus Associated Tumors, German Cancer Research Center, Heidelberg, Germany
| | - Roberto F. Speck
- Division of Infectious Diseases and Hospital Epidemiology, Department of Medicine, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Michele Bernasconi
- Experimental Infectious Diseases and Cancer Research, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Children’s Research Center, University Children’s Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - David Nadal
- Experimental Infectious Diseases and Cancer Research, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Division of Infectious Diseases and Hospital Epidemiology, University Children’s Hospital of Zurich, University of Zurich, Zurich, Switzerland
- Children’s Research Center, University Children’s Hospital Zurich, University of Zurich, Zurich, Switzerland
- * E-mail:
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Au AC, Hernandez PA, Lieber E, Nadroo AM, Shen YM, Kelley KA, Gelb BD, Diaz GA. Protein tyrosine phosphatase PTPN14 is a regulator of lymphatic function and choanal development in humans. Am J Hum Genet 2010; 87:436-44. [PMID: 20826270 DOI: 10.1016/j.ajhg.2010.08.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2010] [Revised: 08/03/2010] [Accepted: 08/17/2010] [Indexed: 11/16/2022] Open
Abstract
The lymphatic vasculature is essential for the recirculation of extracellular fluid, fat absorption, and immune function and as a route of tumor metastasis. The dissection of molecular mechanisms underlying lymphangiogenesis has been accelerated by the identification of tissue-specific lymphatic endothelial markers and the study of congenital lymphedema syndromes. We report the results of genetic analyses of a kindred inheriting a unique autosomal-recessive lymphedema-choanal atresia syndrome. These studies establish linkage of the trait to chromosome 1q32-q41 and identify a loss-of-function mutation in PTPN14, which encodes a nonreceptor tyrosine phosphatase. The causal role of PTPN14 deficiency was confirmed by the generation of a murine Ptpn14 gene trap model that manifested lymphatic hyperplasia with lymphedema. Biochemical studies revealed a potential interaction between PTPN14 and the vascular endothelial growth factor receptor 3 (VEGFR3), a receptor tyrosine kinase essential for lymphangiogenesis. These results suggest a unique and conserved role for PTPN14 in the regulation of lymphatic development in mammals and a nonconserved role in choanal development in humans.
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Affiliation(s)
- Audrey C Au
- Department of Genetics & Genomic Sciences, Mount Sinai School of Medicine, New York, NY 10029, USA
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Abstract
BACKGROUND Cellular oxidative stress is an important factor in asthma and is thought to be the principle mechanism by which oxidant pollutants such as ozone and particulates mediate their pro-inflammatory effects. Endogenous Phase II enzymes abrogate oxidative stress through the scavenging of reactive oxygen species and metabolism of reactive chemicals. OBJECTIVE We conducted a placebo-controlled dose escalation trial to investigate the in vivo effects of sulforaphane, a naturally occurring potent inducer of Phase II enzymes, on the expression of glutathione-s-transferase M1 (GSTM1), glutathione-s-transferase P1 (GSTP1), NADPH quinone oxidoreductase (NQO1), and hemoxygenase-1 (HO-1) in the upper airway of human subjects. METHODS Study subjects consumed oral sulforaphane doses contained in a standardized broccoli sprout homogenate (BSH). RNA expression for selected Phase II enzymes was measured in nasal lavage cells by RT-PCR before and after sulforaphane dosing. RESULTS All subjects tolerated oral sulforaphane dosing without significant adverse events. Increased Phase II enzyme expression in nasal lavage cells occurred in a dose-dependent manner with maximal enzyme induction observed at the highest dose of 200 g broccoli sprouts prepared as BSH. Significant increases were seen in all sentinel Phase II enzymes RNA expression compared to baseline. Phase II enzyme induction was not seen with ingestion of non-sulforaphane containing alfalfa sprouts. CONCLUSION Oral sulforaphane safely and effectively induces mucosal Phase II enzyme expression in the upper airway of human subjects. This study demonstrates the potential of antioxidant Phase II enzymes induction in the human airway as a strategy to reduce the inflammatory effects of oxidative stress. CLINICAL IMPLICATIONS This study demonstrates the potential of enhancement of Phase II enzyme expression as a novel therapeutic strategy for oxidant induced airway disease. CAPSULE SUMMARY A placebo-controlled dose escalation trial demonstrated that naturally occurring sulforaphane from broccoli sprouts can induce a potent increase in antioxidant Phase II enzymes in airway cells.
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Affiliation(s)
- Marc A Riedl
- The Hart and Louis Laboratory, Clinical Immunology and Allergy, Department of Medicine, UCLA David Geffen School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.
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Hou DF, Wang SL, He ZM, Yang F, Chen ZC. Expression of CYP2E1 in human nasopharynx and its metabolic effect in vitro. Mol Cell Biochem 2006; 298:93-100. [PMID: 17146594 DOI: 10.1007/s11010-006-9356-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Accepted: 10/16/2006] [Indexed: 10/23/2022]
Abstract
It was evident that nitrosamines can act directly on target tissue and result in carcinogenesis. As has been shown, the carcinogenic activity of nitrosamines relied on its bioactivation by Cytochrome P450 2E1 (CYP2E1). In this study, we investigated the expression of CYP2E1 in Nasopharyngeal carcinoma (NPC) cells, embryonic nasopharyngeal epithelial tissue (ENET) specimens, and NPC biopsies by RT-PCR analysis. CYP2E1 was expressed in all NPC cell lines (6/6, including 7429) and ENET (6/6), and 80% of NPC biopsie (8/10). The fact that Human nasopharynx expresses CYP2E1 suggests that CYP2E1 may play an important role in the course of NPC by indirect carcinogens nitrosamines. To further evaluate the function of CYP2E1, the CYP2E1 was stably expressed in the cell line NIH 3T3/rtTA under a tetracycline-controlled transactivator. The expression of CYP2E1 was tightly regulated in a dose-dependent manner by Doxycycline (Dox) When the catalytic activity of CYP2E1 was assayed, the result showed that the generation of 6-hydroxychlorzoxazone (6-OH-CZ) from chlorzoxazone (CZ) was dose- and time-dependent on Dox addition to the medium. In the presence of 1 microg/ml Dox, the CZ 6-hydroxylase activity of the cell line was found to be 0.986 +/- 0.034 nmol/10(6) cells/h. The metabolic activation of Tet/3T3/2E1-6 cells was also assayed by N,N'-dinitrosopiperazine (DNP) cytotoxicity, and the viability of Tet/3T3/2E1-6 cells treated with Dox was lower than that of untreated cells with a significant difference between them in 80 and 160 microg/ml DNP (P ( 0.05, t test. This cell line will be useful not only to assess the metabolic characteristics of CYP2E1, but also will be useful to investigate the role of CYP2E1 in metabolic activation of carcinogenic nitrosamines in vitro.
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Affiliation(s)
- De-Fu Hou
- Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, 410078, P.R. China
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Kondo S, Seo SY, Yoshizaki T, Wakisaka N, Furukawa M, Joab I, Jang KL, Pagano JS. EBV latent membrane protein 1 up-regulates hypoxia-inducible factor 1alpha through Siah1-mediated down-regulation of prolyl hydroxylases 1 and 3 in nasopharyngeal epithelial cells. Cancer Res 2006; 66:9870-7. [PMID: 17047048 DOI: 10.1158/0008-5472.can-06-1679] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypoxia-inducible factor 1 (HIF1) is up-regulated in most malignant tumors usually via interruption of ubiquitination and proteasomal degradation of its subunit alpha. Recently, we have shown that the principal EBV oncoprotein, latent membrane protein 1 (LMP1), activates HIF1alpha and subsequently expression of HIF1-responsive genes in epithelial cells. Here, we explore the mechanism for HIF1alpha activation by LMP1 in nasopharyngeal epithelial cells: LMP1 up-regulates the level of Siah1 E3 ubiquitin ligase by enhancing its stability, which subsequently induces proteasomal degradation of prolyl HIF-hydroxylases 1 and 3 that normally mark HIF1alpha for degradation. As a result, LMP1 prevents formation of von Hippel-Lindau/HIF1alpha complex, as shown by coimmunoprecipitation analyses. Thus, Siah1 is implicated in the regulation of HIF1alpha and is involved in a recently appreciated aspect of EBV-mediated tumorigenesis, namely, the angiogenesis process triggered by LMP1.
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Affiliation(s)
- Satoru Kondo
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Brock TG. Expression of 5-lipoxygenase in specialized epithelial cells of nasopharyngeal-associated lymphoid tissue. J Mol Histol 2006; 36:475-81. [PMID: 16733792 DOI: 10.1007/s10735-006-9022-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Accepted: 03/16/2006] [Indexed: 01/03/2023]
Abstract
Leukotrienes are lipid mediators that are produced primarily by certain types of leukocytes. The synthesis of the leukotriene LTB(4) is initiated by the enzyme 5-lipoxygenase and completed by LTA(4) hydrolase. Epithelial cells constitutively express LTA(4) hydrolase but normally lack 5-lipoxygenase. In this study, we report that the stratified squamous epithelial cells from inflamed or hyperplastic tissues of palatine and pharyngeal tonsils (nasopharyngeal-associated lymphoid tissue) express 5-lipoxygenase protein. The localization of 5-lipoxygenase was indicated by immunohistochemical staining and presence confirmed by immunoblot. Positive staining for 5-lipoxygenase in infiltrating leukocytes in inflamed tissues served as internal positive controls for immunohistochemical staining. Staining for 5-lipoxygenase in appendix tissue was negative for epithelial cells while positive for polymorphonuclear leukocytes, indicating that 5-lipoxygenase expression is not a general feature of epithelial cells in mucosa-associated lymphoid tissue. In tonsils, 5-lipoxygenase staining was pronounced in broad regions but reduced or absent in others, suggesting regional regulation of expression. Epithelial cells of tonsils were also positive for 5-lipoxygenase activating protein and leukotriene A(4) hydrolase, indicating a capacity to produce LTB(4). Taken together, these results suggest that the specialized epithelial cells of the mucosa-associated lymphoid tissue of human tonsils can synthesize LTB(4). This lipid mediator may serve to modulate the function of cells within the lymphoid tissue as well as promote an inflammatory response.
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Affiliation(s)
- Thomas G Brock
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-0642, USA.
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Jiang JH, Jia WH, Qin HD, Liang H, Pan ZG, Zeng YX. [Expression of cytochrome P450 enzymes in human nasopharyngeal carcinoma and non-cancerous nasopharynx tissue]. Ai Zheng 2004; 23:672-7. [PMID: 15191668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
BACKGROUND & OBJECTIVE The etiology of nasopharyngeal carcinoma (NPC) is associated with environmental and hereditary factors. Xenobiotics from environment must be activated to derive carcinogens. Several cytochrome P450 (CYP450) metabolic enzymes participate to the activation of pre-carcinogens, and the genetic polymorphism of those genes is associated with metabolic polymorphism and susceptibility to cancer. We performed a preliminary investigation on the xenobiotics metabolism of human nasopharynx by determining the expression of CYP450 genes in NPC and non-cancerous nasopharynx tissues. METHODS The following two methods were used: (1)A cDNA library from the mixed RNA sample of seven non-cancerous nasopharynx tissues was generated, followed by clone sequencing and bioinformatics analysis. (2)RNA of 14 NPC and 8 non-cancerous nasopharynx tissues were reversely transcribed, and the expression of CYP450 genes in those samples was determined by PCR amplification. RESULTS Eight ESTs of CYP450 genes including CYP1B1, CYP2F1, CYP2J2, CYP4B1, CYP4F12, CYP5A(TBXAS1), CYP20A1, and CYP51A1 were detected in non-cancerous nasopharynx cDNA library, among these CYP4B1 exhibited the highest expression level with 16 copies of ESTs. Positive expression of fourteen CYP450 genes including CYP1A1, CYP1B1, CYP2A6, CYP2A13, CYP2B6, CYP2C8, CYP2C9, CYP2D6, CYP2E1, CYP2F1, CYP3A4, CYP3A5, CYP3A7, and CYP4B1 were detected by RT-PCR, among these, CYP1B1, CYP2B6, and CYP4B1 had also been detected in the cDNA library. A total of 19 CYP450 genes expression were detected in NPC and non-cancerous nasopharynx tissues, and the expression levels of CYP1B1, CYP2C8, CYP2C9, CYP2D6, CYP3A5, and CYP4B1 were higher than those of the other genes. CONCLUSION The expression of a great number of CYP450 genes was detected in human nasopharynx, some of which might participate to the activation of pre-carcinogen in human nasopharynx. Contribution of these genes to the risk of NPC needs further investigation.
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Affiliation(s)
- Ju-Hong Jiang
- Department of Experimental Research, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong, PR China
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Yang J, Deng XY, Gu HH, Xia LQ, Yi W, Cao Y. [Epstein-Barr virus latent membrane protein 1 induces the telomerase activity in human nasopharyngeal epithelial cells]. Shi Yan Sheng Wu Xue Bao 2001; 34:207-11. [PMID: 12549222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
Telomerase activation has been linked to cell immortalization in vitro and tumorigenicity in vivo. In this study, for the first, we reported that Epstein-Barr virus activated the telomerase activity of human nasopharyngeal epithelial cells in the early stage of immortalization as tested by the PCR-ELISA. The telomerase activity in nasopharyngeal epithelial cells was only observed in presenescent cells. It was implicated that Epstein-Barr virus induced the escape of nasopharyngeal epithelial cells from senescence via the activation of telomerase. We further showed that telomerase activation in infected cells was dependent on the protein level of latent membrane protein 1 (LMP1) encoded by Epstein-Barr virus using a Tetracycline regulatory cell line expressing LMP1, pTet-on-LMP1-HNE2. The activity of telomerase in nasopharyngeal cells was decreased when the protein level of LMP1 was blocked by antisense LMP1 plasmid DNA. And the activity of telmerase was also related to the carboxyl terminus of LMP1. It was implicated that the ability of Epstein-Barr virus to suppress senescence is associated with telomerase activation by LMP1.
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Affiliation(s)
- J Yang
- Cancer Research Institute, Hunan Medical University, Changsha Hunan, 410078
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Abstract
Telomeres are specialized structures at the ends of eukaryotic chromosomes which are composed of simple repetitive G-rich hexameric sequences. Activation of telomerase, a ribonucleoprotein that synthesizes telomeric DNA, is found in most malignant tumors. However, little data is available concerning the correlation between telomerase activity and NPC (nasopharyngeal carcinoma). In this study, telomerase activation was determined using the TRAP (telomerase repeat amplification protocol) assay in 62 nasopharyngeal biopsies (25 NPC, 25 non-malignant nasopharyngeal lymphoid tissues, 12 post-irradiated nasopharyngeal tissues). The results showed that strong telomerase activity was present in both NPC and non-malignant nasopharyngeal biopsies. Post-irradiated nasopharyngeal samples had a significantly lower telomerase activity than NPC and non-malignant nasopharyngeal lymphoid tissues. It is well known that nasopharyngeal tissue is infiltrated by numerous lymphocytes, which might retain telomerase activity. Therefore, the finding that the telomerase activation was lowest in post-irradiated nasopharyngeal tissues is reasonable because of the destruction of activated lymphocytes and NPC by radiation. NPC biopsies with positive lymph node involvement exhibited higher levels of telomerase compared to those without lymph node involvement. Our data indicate a positive association between telomerase activity and tumor potential for lymphatic spreading in limited local tumors. In addition, telomerase activity may be useful as a diagnostic marker in the detection of tumor cells in recurrent NPC, but not in primary NPC.
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Affiliation(s)
- C F Hwang
- Department of Otolaryngology, Chang-Gung Memorial Hospital, Kaohsiung, Taiwan
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Tsutsumi H, Takeuchi R, Ohsaki M, Seki K, Chiba S. Respiratory syncytial virus infection of human respiratory epithelial cells enhances inducible nitric oxide synthase gene expression. J Leukoc Biol 1999; 66:99-104. [PMID: 10410996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
The induction kinetics of the mRNA of interferon regulatory factor 1 (IRF-1), inducible nitric oxide synthase (iNOS), and proinflammatory cytokines in respiratory syncytial virus (RSV)-infected human type 2 alveolar epithelial cells (A549 cells) were analyzed semiquantitatively by RT-PCR. RSV enhanced IRF-1 and iNOS mRNA expression as early as 4 h after RSV infection and this enhancement lasted several hours. No IFN-gamma gene expression was observed during the whole course of the infection. Expression of IFN-beta, IL-1beta, and TNF-alpha genes was observed slightly at 4 h and became marked 7 h after infection. Addition of neutralizing antibodies to these cytokines to the culture had no effect on the induction of iNOS mRNA. The iNOS transcriptional activity in RSV-infected cells was significantly enhanced by an exogenous cytokine mixture (IL-1beta, TNF-alpha, and IFN-gamma). An apparent nitric oxide (NO) production was identified only when cytokines were added together with RSV infection. A significant increase of iNOS gene expression was observed in nasopharyngeal exudate cells obtained from infants during the acute phase of RSV bronchiolitis. These observations suggest that RSV infection of human respiratory epithelial cells induces the iNOS gene both in vitro and in vivo; this induction may occur rather promptly and involves transcriptional activator IRF-1 induced by the RSV infection itself. The iNOS gene, which is initially induced by RSV infection, may be further enhanced in a paracrine fashion by proinflammatory cytokines released by infection-activated inflammatory cells.
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Affiliation(s)
- H Tsutsumi
- Department of Pediatrics, Sapporo Medical University School of Medicine, Japan
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Eriksson M, Granström G, Wretlind B, Granström M, Askelöf P. Bordetella pertussis adenylate cyclase activity in nasopharyngeal aspirates for rapid diagnosis of whooping cough in relation to culture and serology. Scand J Infect Dis 1991; 23:731-5. [PMID: 1815336 DOI: 10.3109/00365549109024301] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Adenylate cyclase activity, measured in 201 nasopharyngeal aspirates from patients presenting with own or parental suspicion of whooping cough, was compared to diagnosis made by culture and by serology in the culture negative cases. The median amount of cyclic AMP in samples from culture negative patients (n = 145) was 0.60 pmoles which differed significantly (p less than 0.001) from the median value 3.28 in samples from culture positive patients (n = 56). The median value 0.70 pmoles of cyclic AMP in samples from culture negative patients who were positive by serology (n = 54) did not differ significantly from the value of 0.57 pmoles in samples from serology negative patients (n = 91). With a limit for positive cyclic AMP set at 2 pmoles, 45 samples were positive. The sensitivity of the assay was 66% (37/56) in culture positive patients while the specificity was 93% (85/91) in the serology negative patients. The positive predictive value for the c-AMP test was 82% (37/45) in relation to culture and 87% (39/45) in relation to culture and/or serology. The results confirmed that measurement of adenylate cyclase activity in nasopharyngeal aspirates by an 1-h incubation method can serve as an early and rapid diagnostic method of pertussis infection. The low sensitivity of the c-AMP assay in samples from serology positive but culture negative patients indicates however, that this assay will have to be supplemented by serology for a high diagnostic sensitivity in all cases of pertussis.
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Affiliation(s)
- M Eriksson
- Department of Vaccine Production, National Bacteriological Laboratory, Stockholm, Sweden
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Wilson JD, Miller H, Gelboin HV, Friedman FK. Variation in inducibility of cytochrome P-450c and aryl hydrocarbon hydroxylase in rat liver, lung, kidney, pancreas and nasopharynx. Pharmacology 1990; 41:256-62. [PMID: 2092329 DOI: 10.1159/000138729] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of 3-methylcholanthrene (MC) treatment on the cytochrome P-450c content of various rat tissues was examined by measuring the level of immunodetectable P-450c in conjunction with its aryl hydrocarbon hydroxylase (AHH) activity. Immunoblots revealed that P-450d was induced in the nasopharynx and pancreas in addition to its previously reported induction in the liver, lung and kidney. In contrast to P-450c, induction of the immunorelated P-450d was observed only in the liver. The specific content of immunodetected P-450c in the tissue homogenates decreased in the order: liver, nasopharynx, pancreas, lung, kidney. The corresponding AHH activities decreased in the order: liver, kidney, lung, nasopharynx, pancreas. The ratio of AHH activity to P-450c content varied widely among tissues: ratios of 37.2:1.7:0.47:0.04:0.02 were obtained for the kidney, liver, lung, nasopharynx and pancreas, respectively. The absence of a direct relationship between the levels of AHH and P-450c indicates that the extrahepatic activity may partially derive from P-450 forms other than P-450c and/or the specific activity of P-450c varies among different tissues.
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Affiliation(s)
- J D Wilson
- Laboratory of Molecular Carcinogenesis, National Cancer Institute, Bethesda, Md
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