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Articles 1 - 30 of 58
Full-Text Articles in Medicine and Health Sciences
Crystal Structure Of Apobec3a Bound To Single-Stranded Dna Reveals Structural Basis For Cytidine Deamination And Specificity, Takahide Kouno, Tania V. Silvas, Brendan J. Hilbert, Shivender Shandilya, Markus-Frederik Bohn, Brian A. Kelch, William E. Royer, Mohan Somasundaran, Nese Kurt Yilmaz, Hiroshi Matsuo, Celia A. Schiffer
Crystal Structure Of Apobec3a Bound To Single-Stranded Dna Reveals Structural Basis For Cytidine Deamination And Specificity, Takahide Kouno, Tania V. Silvas, Brendan J. Hilbert, Shivender Shandilya, Markus-Frederik Bohn, Brian A. Kelch, William E. Royer, Mohan Somasundaran, Nese Kurt Yilmaz, Hiroshi Matsuo, Celia A. Schiffer
Celia A. Schiffer
Nucleic acid editing enzymes are essential components of the immune system that lethally mutate viral pathogens and somatically mutate immunoglobulins, and contribute to the diversification and lethality of cancers. Among these enzymes are the seven human APOBEC3 deoxycytidine deaminases, each with unique target sequence specificity and subcellular localization. While the enzymology and biological consequences have been extensively studied, the mechanism by which APOBEC3s recognize and edit DNA remains elusive. Here we present the crystal structure of a complex of a cytidine deaminase with ssDNA bound in the active site at 2.2 A. This structure not only visualizes the active site …
Dengue Virus Ns2b/Ns3 Protease Inhibitors Exploiting The Prime Side, Kuan-Hung Lin, Akbar Ali, Linah Rusere, Djade I. Soumana, Nese Kurt Yilmaz, Celia A. Schiffer
Dengue Virus Ns2b/Ns3 Protease Inhibitors Exploiting The Prime Side, Kuan-Hung Lin, Akbar Ali, Linah Rusere, Djade I. Soumana, Nese Kurt Yilmaz, Celia A. Schiffer
Celia A. Schiffer
The mosquito-transmitted dengue virus (DENV) infects millions of people in tropical and subtropical regions. Maturation of DENV particles requires proper cleavage of the viral polyprotein, including processing of 8 of the 13 substrate cleavage sites by dengue virus NS2B/NS3 protease. With no available direct-acting antiviral targeting DENV, NS2/NS3 protease is a promising target for inhibitor design. Current design efforts focus on the nonprime side of the DENV protease active site, resulting in highly hydrophilic and nonspecific scaffolds. However, the prime side also significantly modulates DENV protease binding affinity, as revealed by engineering the binding loop of aprotinin, a small protein …
Interdependence Of Inhibitor Recognition In Hiv-1 Protease, Janet L. Paulsen, Florian Leidner, Debra A. Ragland, Nese Kurt Yilmaz, Celia A. Schiffer
Interdependence Of Inhibitor Recognition In Hiv-1 Protease, Janet L. Paulsen, Florian Leidner, Debra A. Ragland, Nese Kurt Yilmaz, Celia A. Schiffer
Celia A. Schiffer
Molecular recognition is a highly interdependent process. Subsite couplings within the active site of proteases are most often revealed through conditional amino acid preferences in substrate recognition. However, the potential effect of these couplings on inhibition and thus inhibitor design is largely unexplored. The present study examines the interdependency of subsites in HIV-1 protease using a focused library of protease inhibitors, to aid in future inhibitor design. Previously a series of darunavir (DRV) analogs was designed to systematically probe the S1' and S2' subsites. Co-crystal structures of these analogs with HIV-1 protease provide the ideal opportunity to probe subsite interdependency. …
Attenuation Of Na/K-Atpase Mediated Oxidant Amplification With Pnaktide Ameliorates Experimental Uremic Cardiomyopathy, Jiang Liu, Jiang Tian, Muhammad Chaudhry, Nader G. Abraham, Joseph I Shapiro
Attenuation Of Na/K-Atpase Mediated Oxidant Amplification With Pnaktide Ameliorates Experimental Uremic Cardiomyopathy, Jiang Liu, Jiang Tian, Muhammad Chaudhry, Nader G. Abraham, Joseph I Shapiro
Nader G. Abraham
We have previously reported that the sodium potassium adenosine triphosphatase (Na/K-ATPase) can effect the amplification of reactive oxygen species. In this study, we examined whether attenuation of oxidant stress by antagonism of Na/K-ATPase oxidant amplification might ameliorate experimental uremic cardiomyopathy induced by partial nephrectomy (PNx). PNx induced the development of cardiac morphological and biochemical changes consistent with human uremic cardiomyopathy. Both inhibition of Na/K-ATPase oxidant amplification with pNaKtide and induction of heme oxygenase-1 (HO-1) with cobalt protoporphyrin (CoPP) markedly attenuated the development of phenotypical features of uremic cardiomyopathy. In a reversal study, administration of pNaKtide after the induction of uremic …
Attenuation Of Na/K-Atpase Mediated Oxidant Amplification With Pnaktide Ameliorates Experimental Uremic Cardiomyopathy, Jiang Liu, Jiang Tian, Muhammad Chaudhry, Nader G. Abraham, Joseph I Shapiro
Attenuation Of Na/K-Atpase Mediated Oxidant Amplification With Pnaktide Ameliorates Experimental Uremic Cardiomyopathy, Jiang Liu, Jiang Tian, Muhammad Chaudhry, Nader G. Abraham, Joseph I Shapiro
Jiang Liu
We have previously reported that the sodium potassium adenosine triphosphatase (Na/K-ATPase) can effect the amplification of reactive oxygen species. In this study, we examined whether attenuation of oxidant stress by antagonism of Na/K-ATPase oxidant amplification might ameliorate experimental uremic cardiomyopathy induced by partial nephrectomy (PNx). PNx induced the development of cardiac morphological and biochemical changes consistent with human uremic cardiomyopathy. Both inhibition of Na/K-ATPase oxidant amplification with pNaKtide and induction of heme oxygenase-1 (HO-1) with cobalt protoporphyrin (CoPP) markedly attenuated the development of phenotypical features of uremic cardiomyopathy. In a reversal study, administration of pNaKtide after the induction of uremic …
Central Role Of Il-23 And Il-17 Producing Eosinophils As Immunomodulatory Effector Cells In Acute Pulmonary Aspergillosis And Allergic Asthma, Evelyn V. Santos Guerra, Chrono K. Lee, Charles A. Specht, Bhawna Yadav, Haibin Huang, Ali Akalin, Jun R. Huh, Christian Mueller, Stuart M. Levitz
Central Role Of Il-23 And Il-17 Producing Eosinophils As Immunomodulatory Effector Cells In Acute Pulmonary Aspergillosis And Allergic Asthma, Evelyn V. Santos Guerra, Chrono K. Lee, Charles A. Specht, Bhawna Yadav, Haibin Huang, Ali Akalin, Jun R. Huh, Christian Mueller, Stuart M. Levitz
Christian Mueller
Aspergillus fumigatus causes invasive pulmonary disease in immunocompromised hosts and allergic asthma in atopic individuals. We studied the contribution of lung eosinophils to these fungal diseases. By in vivo intracellular cytokine staining and confocal microscopy, we observed that eosinophils act as local sources of IL-23 and IL-17. Remarkably, mice lacking eosinophils had a >95% reduction in the percentage of lung IL-23p19+ cells as well as markedly reduced IL-23 heterodimer in lung lavage fluid. Eosinophils killed A. fumigatus conidia in vivo. Eosinopenic mice had higher mortality rates, decreased recruitment of inflammatory monocytes, and decreased expansion of lung macrophages after challenge with …
Hepatitis C Virus-Induced Monocyte Differentiation Into Polarized M2 Macrophages Promotes Stellate Cell Activation Via Tgf-Beta, Banishree Saha, Karen Kodys, Gyongyi Szabo
Hepatitis C Virus-Induced Monocyte Differentiation Into Polarized M2 Macrophages Promotes Stellate Cell Activation Via Tgf-Beta, Banishree Saha, Karen Kodys, Gyongyi Szabo
Gyongyi Szabo
BACKGROUND and AIMS: Monocyte and macrophage (MPhi) activation contributes to the pathogenesis of chronic hepatitis C virus (HCV) infection. Disease pathogenesis is regulated by both liver-resident MPhis and monocytes recruited as precursors of MPhis into the damaged liver. Monocytes differentiate into M1 (classic/proinflammatory) or M2 (alternative/anti-inflammatory) polarized MPhis in response to tissue microenvironment. We hypothesized that HCV-infected hepatoma cells (infected with Japanese fulminant hepatitis-1 [Huh7.5/JFH-1]) induce monocyte differentiation into polarized MPhis. METHODS: Healthy human monocytes were co-cultured with Huh7.5/JFH-1 cells or cell-free virus for 7 days and analyzed for MPhi markers and cytokine levels. A similar analysis was performed on …
Tumour Inflammasome-Derived Il-1b Recruits Neutrophils And Improves Local Recurrence-Free Survival In Ebv-Induced Nasopharyngeal Carcinoma, Lih-Chyang Chen, Li-Jie Wang, Nang-Ming Tsang, David M. Ojcius, Chia-Chen Chen, Chun-Nan Ouyang, Chuen Hsueh, Ying Liang, Kai-Ping Chang, Chiu-Chin Chen, Yu-Sun Chang
Tumour Inflammasome-Derived Il-1b Recruits Neutrophils And Improves Local Recurrence-Free Survival In Ebv-Induced Nasopharyngeal Carcinoma, Lih-Chyang Chen, Li-Jie Wang, Nang-Ming Tsang, David M. Ojcius, Chia-Chen Chen, Chun-Nan Ouyang, Chuen Hsueh, Ying Liang, Kai-Ping Chang, Chiu-Chin Chen, Yu-Sun Chang
David M. Ojcius
Inflammasomes sense infection and cellular damage and are critical for triggering inflammation through IL-1β production. In carcinogenesis, inflammasomes may have contradictory roles through facilitating antitumour immunity and inducing oncogenic factors. Their function in cancer remains poorly characterized. Here we show that the NLRP3, AIM2 and RIG-I inflammasomes are overexpressed in Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC), and expression levels correlate with patient survival. In tumour cells, AIM2 and RIG-I are required for IL-1β induction by EBV genomic DNA and EBV-encoded small RNAs, respectively, while NLRP3 responds to extracellular ATP and reactive oxygen species. Irradiation and chemotherapy can further activate AIM2 …
The Pathological Effects Of Ccr2+ Inflammatory Monocytes Are Amplified By An Ifnar1-Triggered Chemokine Feedback Loop In Highly Pathogenic Influenza Infection, Sue-Jane Lin, Ming Lo, Rei-Lin Kuo, Shin-Ru Shih, David M. Ojcius, Jean Lu, Chien-Kuo Lee, Hui-Chen Chen, Meei Yun Lin, Chuen-Miin Leu, Chia-Ni Lin, Ching-Hwa Tsai
The Pathological Effects Of Ccr2+ Inflammatory Monocytes Are Amplified By An Ifnar1-Triggered Chemokine Feedback Loop In Highly Pathogenic Influenza Infection, Sue-Jane Lin, Ming Lo, Rei-Lin Kuo, Shin-Ru Shih, David M. Ojcius, Jean Lu, Chien-Kuo Lee, Hui-Chen Chen, Meei Yun Lin, Chuen-Miin Leu, Chia-Ni Lin, Ching-Hwa Tsai
David M. Ojcius
Background: Highly pathogenic influenza viruses cause high levels of morbidity, including excessive infiltration of leukocytes into the lungs, high viral loads and a cytokine storm. However, the details of how these pathological features unfold in severe influenza infections remain unclear. Accumulation of Gr1 + CD11b + myeloid cells has been observed in highly pathogenic influenza infections but it is not clear how and why they accumulate in the severely inflamed lung. In this study, we selected this cell population as a target to investigate the extreme inflammatory response during severe influenza infection. Results: We established H1N1 IAV-infected mouse models using …
Tolerance Of The Fetus By The Maternal Immune System: Role Of Inflammatory Mediators At The Feto-Maternal Interface, Colette Kanellopoulos-Langevin, Stephane M. Caucheteux, Philippe Verbeke, David M. Ojcius
Tolerance Of The Fetus By The Maternal Immune System: Role Of Inflammatory Mediators At The Feto-Maternal Interface, Colette Kanellopoulos-Langevin, Stephane M. Caucheteux, Philippe Verbeke, David M. Ojcius
David M. Ojcius
The adaptive immune system of placental mammals has evolved to tolerate the fetus. Rejection of the fetus by adaptive immune responses is therefore a rare event, with abortion being caused more frequently by inflammation in the placenta. This review will cover recent aspects of immune privilege and the innate immune system at the feto-maternal interface, citing examples of the role played by microbial infections in fetal demise.
Ph And Calcium Dependence Of Hemolysis Due To Rickettsia Prowazekii: Comparison With Phospholipase Activity, David M. Ojcius, M. Thibon, C. Mounier, Alice Dautry-Varsat
Ph And Calcium Dependence Of Hemolysis Due To Rickettsia Prowazekii: Comparison With Phospholipase Activity, David M. Ojcius, M. Thibon, C. Mounier, Alice Dautry-Varsat
David M. Ojcius
Rickettsia prowazekii invades nucleated cells through phagocytosis and subsequently proliferates in the cytoplasm of the host cell. Hemolysis and a phospholipase A2 (PLA2) activity at neutral pHs have previously been reported; even though the phagosomal environment is most likely acidic. We here show that R. prowazekii and R. typhi also lyse erythrocytes at mildly acidic pHs, compatible with an early phagosomal compartment. For R. prowazekii, hemolysis at an acidic pH but not a neutral pH is enhanced by Ca2+, raising the possibility that more than one membranolytic factor may be produced by the rickettsiae. The rickettsiae alone display PLA2 activity, …
The Danger Signal Adenosine Induces Persistence Of Chlamydial Infection Through Stimulation Of A2b Receptors, Matthew A. Pettengill, Verissa W. Lam, David M. Ojcius
The Danger Signal Adenosine Induces Persistence Of Chlamydial Infection Through Stimulation Of A2b Receptors, Matthew A. Pettengill, Verissa W. Lam, David M. Ojcius
David M. Ojcius
Infections with intracellular bacteria such as chlamydiae affect the majority of the world population. Infected tissue inflammation and granuloma formation help contain the short-term expansion of the invading pathogen, leading also to local tissue damage and hypoxia. However, the effects of key aspects of damaged inflamed tissues and hypoxia on continued infection with intracellular bacteria remain unknown. We find that development of Chlamydia trachomatis is reversibly retarded by prolonged exposure of infected cells to extracellular adenosine, a hallmark of hypoxia and advanced inflammation. In epithelial cells, this effect was mediated by the A2b adenosine receptor, unique in the adenosine receptor …
Trail-R1 Is A Negative Regulator Of Pro-Inflammatory Responses And Modulates Long-Term Sequelae Resulting From Chlamydia Trachomatis Infections In Humans, Mufadhal Al-Kuhlani, James Rothchild, Sukumar Pal, Luis M. De La Maza, Sander Ouberg, Servaas A. Morré, Deborah Dean, David M. Ojcius
Trail-R1 Is A Negative Regulator Of Pro-Inflammatory Responses And Modulates Long-Term Sequelae Resulting From Chlamydia Trachomatis Infections In Humans, Mufadhal Al-Kuhlani, James Rothchild, Sukumar Pal, Luis M. De La Maza, Sander Ouberg, Servaas A. Morré, Deborah Dean, David M. Ojcius
David M. Ojcius
The immune system eliminates Chlamydia trachomatis infection through inflammation. However, uncontrolled inflammation can enhance pathology. In mice, TNF-related apoptosis-inducing ligand receptor (TRAIL-R), known for its effects on apoptosis, also regulates inflammation. In humans, the four homologues of TRAIL-R had never been investigated for effects on inflammation. Here, we examined whether TRAIL-R regulates inflammation during chlamydial infection. We examined TRAIL-R1 single nucleotide polymorphisms (SNPs) in an Ecuadorian cohort with and without C. trachomatis infections. There was a highly significant association for the TRAIL+626 homozygous mutant GG for infection vs no infection in this population. To confirm the results observed in the …
Susceptibility Of Chlamydia Trachomatis To The Excipient Hydroxy-Ethylcellulose: Ph And Concentration Dependence Of Antimicrobial Activity, Ali A. Abdul-Sater, David M. Ojcius, M. P. Meyer
Susceptibility Of Chlamydia Trachomatis To The Excipient Hydroxy-Ethylcellulose: Ph And Concentration Dependence Of Antimicrobial Activity, Ali A. Abdul-Sater, David M. Ojcius, M. P. Meyer
David M. Ojcius
Hydroxyethyl cellulose (HEC) is used as a neutral excipient in microbicides used against sexually transmitted pathogens. However, HEC inhibits the infection of cervical epithelial cells by Chlamydia trachomatis at pH 5 in a concentration-dependent manner. At pH 7, infection is inversely dependent on the concentration of HEC, possibly due to pH-dependent calcium sequestration.
The Anti-Tumorigenic Mushroom Agaricus Blazei Murill Enhances Il-1Β Production And Activates The Nlrp3 Inflammasome In Human Macrophages, Tsung-Teng Huang, David M. Ojcius, John Ding-E. Young, Yi-Hui Wu, Yun-Fei Ko, Tsui-Yin Wong, Cheng-Yeu Wu, Chia-Chen Lu, Hsin-Chih Lai
The Anti-Tumorigenic Mushroom Agaricus Blazei Murill Enhances Il-1Β Production And Activates The Nlrp3 Inflammasome In Human Macrophages, Tsung-Teng Huang, David M. Ojcius, John Ding-E. Young, Yi-Hui Wu, Yun-Fei Ko, Tsui-Yin Wong, Cheng-Yeu Wu, Chia-Chen Lu, Hsin-Chih Lai
David M. Ojcius
Agaricus blazei Murill (AbM) has been reported to possess immune activity against tumors and infections through stimulation of mononuclear phagocytes. Recently, AbM extract was shown to induce the production of the pro-inflammatory cytokine, interleukin-1β (IL-1β), in human monocytes. IL-1β is a key pro-inflammatory cytokine produced by activated macrophages and monocytes and its secretion is strictly controlled by the inflammasome. The purpose of this study is to investigate the effect of AbM water extracts on the regulation of IL-1β production and activation of the NLRP3 inflammasome in human THP-1 macrophages. The NLRP3 inflammasome consists of an NLRP3 receptor, an adaptor protein …
The Microtubule-Associated Protein, Eb1, Links Aim2 Inflammasomes With Autophagy-Dependent Secretion, Li-Jie Wang, Hsin-Yi Huang, Meng-Pin Huang, Willisa Liou, Ya-Ting Chang, Chih-Ching Wu, David M. Ojcius, Yu-Sun Chang
The Microtubule-Associated Protein, Eb1, Links Aim2 Inflammasomes With Autophagy-Dependent Secretion, Li-Jie Wang, Hsin-Yi Huang, Meng-Pin Huang, Willisa Liou, Ya-Ting Chang, Chih-Ching Wu, David M. Ojcius, Yu-Sun Chang
David M. Ojcius
Inflammasomes are multi-protein complexes that regulate chronic inflammation-associated diseases by inducing interleukin-1 β (IL-1β) secretion. Numerous components involved in inflammasome activation have been identified, but the mechanisms of inflammasome-mediated IL-1β secretion have not yet been fully explored. Here, we demonstrate that end-binding protein 1 (EB1), which is required for activation of AIM2 inflammasome complex, links the AIM2 inflammasome to autophagy-dependent secretion. Imaging studies revealed that AIM2 inflammasomes colocalize with microtubule organizing centers and autophagosomes. Biochemical analyses showed that poly(dA-dT)-activated AIM2 inflammasomes induce autophagy and IL-1β secretion in an LC3-dependent fashion. Furthermore, depletion of EB1 decreases autophagic shedding and intracellular trafficking. …
Role Of Proapoptotic Bax In Propagation Of Chlamydia Muridarum (The Mouse Pneumonitis Strain Of Chlamydia Trachomatis) And The Host Inflammatory Response, Jean-Luc Perfettini, David M. Ojcius, Charles W. Andrews Jr., Stanley J. Korsmeyer, Roger G. Rank, Toni Darville
Role Of Proapoptotic Bax In Propagation Of Chlamydia Muridarum (The Mouse Pneumonitis Strain Of Chlamydia Trachomatis) And The Host Inflammatory Response, Jean-Luc Perfettini, David M. Ojcius, Charles W. Andrews Jr., Stanley J. Korsmeyer, Roger G. Rank, Toni Darville
David M. Ojcius
The BCL-2 family member BAX plays a critical role in regulating apoptosis. Surprisingly, bax-deficient mice display limited phenotypic abnormalities. Here we investigate the effect of BAX on infection by the sexually transmitted pathogen,Chlamydia muridarum (the mouse pneumonitis strain ofChlamydia trachomatis). Bax −/−cells are relatively resistant to Chlamydia-induced apoptosis, and fewer bacteria are recovered after two infection cycles from Bax −/− cells than from wild-type cells. These results suggest that BAX-dependent apoptosis may be used to initiate a new round of infection, most likely by releasingChlamydia-containing apoptotic bodies from infected cells that could be internalized by neighboring uninfected cells. Nonetheless, infected …
Separate Metabolic Pathways Leading To Dna Fragmentation And Apoptotic Nuclear Chromatin Condensation, D. Sun, Shibo Jiang, Li-Mou Zheng, David M. Ojcius, John Ding-E. Young
Separate Metabolic Pathways Leading To Dna Fragmentation And Apoptotic Nuclear Chromatin Condensation, D. Sun, Shibo Jiang, Li-Mou Zheng, David M. Ojcius, John Ding-E. Young
David M. Ojcius
Apoptosis is the predominant form of cell death observed in a variety of physiological and pathological conditions such as cancer involution, insect metamorphosis, the development of the immune and nervous systems, and embryogenesis. The typical nuclear changes taking place in apoptotic cells include extensive condensation of chromatin and internucleosomal DNA fragmentation into units of 200 base pairs. However, the mechanisms responsible for both chromatin condensation and DNA fragmentation have yet to be elucidated. In this study, micrococcal nuclease and the divalent cations, Ca2+ and Mg2+, were applied to isolated nuclei in an attempt to reconstitute in vitro the digestion of …
Reversible Inhibition Of Chlamydia Trachomatis Infection In Epithelial Cells Due To Stimulation Of P2x4 Receptors, Matthew A. Pettengill, Camila Marques-Da-Silva, Maria Luisa Avila, Verissa W. Lam, Ikechukwu Ollawa, Ali Abdul-Sater, Robson Coutinho-Silva, Georg Hacker, David M. Ojcius, Suellen D'Arc Dos Santos Oliveira
Reversible Inhibition Of Chlamydia Trachomatis Infection In Epithelial Cells Due To Stimulation Of P2x4 Receptors, Matthew A. Pettengill, Camila Marques-Da-Silva, Maria Luisa Avila, Verissa W. Lam, Ikechukwu Ollawa, Ali Abdul-Sater, Robson Coutinho-Silva, Georg Hacker, David M. Ojcius, Suellen D'Arc Dos Santos Oliveira
David M. Ojcius
Bacterial infections of the mucosal epithelium are a major cause of human disease. The prolonged presence of microbial pathogens stimulates inflammation of the local tissues, which leads to changes in the molecular composition of the extracellular milieu. A well-characterized molecule that is released to the extracellular milieu by stressed or infected cells is extracellular ATP and its ecto-enzymatic degradation products, which function as signaling molecules through ligation of purinergic receptors. There has been little information, however, on the effects of the extracellular metabolites on bacterial growth in inflamed tissues. Millimolar concentrations of ATP have been previously shown to inhibit irreversibly …
Role Of Bcl-2 Family Members In Caspase-Independent Apoptosis Due To Chlamydia Infection, Jean-Luc Perfettini, John C. Reed, Nicole Israel, Jean-Claude Martinou, Alice Dautry-Varsat, David M. Ojcius
Role Of Bcl-2 Family Members In Caspase-Independent Apoptosis Due To Chlamydia Infection, Jean-Luc Perfettini, John C. Reed, Nicole Israel, Jean-Claude Martinou, Alice Dautry-Varsat, David M. Ojcius
David M. Ojcius
Infection with an obligate intracellular bacterium, the Chlamydia trachomatis lymphogranuloma venereum (LGV/L2) strain or the guinea pig inclusion conjunctivitis serovar of Chlamydia psittaci, leads to apoptosis of host cells. The apoptosis is not affected by a broad-spectrum caspase inhibitor, and caspase-3 is not activated in infected cells, suggesting that apoptosis mediated by these two strains of Chlamydia is independent of known caspases. Overexpression of the proapoptotic Bcl-2 family member, Bax, was previously shown to induce caspase-independent apoptosis, and we find that Bax is activated and translocates from the cytosol to the mitochondria in C. psittaci-infected cells. C. psittaci-induced apoptosis is …
Pyk2 Activates The Nlrp3 Inflammasome By Directly Phosphorylating Asc And Contributes To Inflammasome-Dependent Peritonitis, I-Che Chung, Chun-Nan Ouyang, Sheng-Ning Yuan, Hsin-Pai P. Li, Jeng-Ting Chen, Hui-Ru Shieh, Yu-Jen Chen, David M. Ojcius, Ching-Liang Chu, Jau-Song Yu, Yu-Sun Chang, Lih-Chyang Chen
Pyk2 Activates The Nlrp3 Inflammasome By Directly Phosphorylating Asc And Contributes To Inflammasome-Dependent Peritonitis, I-Che Chung, Chun-Nan Ouyang, Sheng-Ning Yuan, Hsin-Pai P. Li, Jeng-Ting Chen, Hui-Ru Shieh, Yu-Jen Chen, David M. Ojcius, Ching-Liang Chu, Jau-Song Yu, Yu-Sun Chang, Lih-Chyang Chen
David M. Ojcius
The inflammasome adaptor protein, ASC, contributes to both innate immune responses and inflammatory diseases via self-oligomerization, which leads to the activation of the protease, caspase-1. Here, we report that the cytosolic tyrosine kinases, FAK and Pyk2, are differentially involved in NLRP3 and AIM2 inflammasome activation. The inhibition of FAK and Pyk2 with RNA interference or chemical inhibitors dramatically abolished ASC oligomerization, caspase-1 activation, and IL-1β secretion in response to NLRP3 or AIM2 stimulation. Pyk2 is phosphorylated by the kinase Syk and relocalizes to the ASC specks upon NLRP3 inflammasome activation. Pyk2, but not FAK, could directly phosphorylate ASC at Tyr146, …
Recruitment Of Bad By The Chlamydia Trachomatis Vacuole Correlates With Host-Cell Survival, Philippe Verbeke, Lynn Welter-Stahl, S. Ying, J. Hansen, Georg Hacker, Toni Darville, David M. Ojcius
Recruitment Of Bad By The Chlamydia Trachomatis Vacuole Correlates With Host-Cell Survival, Philippe Verbeke, Lynn Welter-Stahl, S. Ying, J. Hansen, Georg Hacker, Toni Darville, David M. Ojcius
David M. Ojcius
Chlamydiae replicate intracellularly in a vacuole called an inclusion. Chlamydial-infected host cells are protected from mitochondrion-dependent apoptosis, partly due to degradation of BH3-only proteins. The host-cell adapter protein 14-3-3β can interact with host-cell apoptotic signaling pathways in a phosphorylation-dependent manner. In Chlamydia trachomatis-infected cells, 14-3-3β co-localizes to the inclusion via direct interaction with a C. trachomatis-encoded inclusion membrane protein. We therefore explored the possibility that the phosphatidylinositol-3 kinase (PI3K) pathway may contribute to resistance of infected cells to apoptosis. We found that inhibition of PI3K renders C. trachomatis-infected cells sensitive to staurosporine-induced apoptosis, which is accompanied by mitochondrial cytochrome c …
Purification And Ligand Binding Of A Soluble Class I Mhc Molecule Consisting Of The First Three Domains Of H-2kd Fused To B2-Microglobulin Expressed In The Baculovirus/Insect Cell System, Francois Godeau, Immanuel F. Luescher, David M. Ojcius, Cecile Saucier, Estelle Mottez, Lucien Cabanie, Philippe Kourilsky
Purification And Ligand Binding Of A Soluble Class I Mhc Molecule Consisting Of The First Three Domains Of H-2kd Fused To B2-Microglobulin Expressed In The Baculovirus/Insect Cell System, Francois Godeau, Immanuel F. Luescher, David M. Ojcius, Cecile Saucier, Estelle Mottez, Lucien Cabanie, Philippe Kourilsky
David M. Ojcius
A recombinant baculovirus encoding a single-chain murine major histocompatibility complex class I molecule in which the first three domains of H-2Kd are fused to beta 2-microglobulin (beta 2-m) via a 15-amino acid linker has been isolated and used to infect lepidopteran cells. A soluble, 391-amino acid single-chain H-2Kd (SC-Kd) molecule of 48 kDa was synthesized and glycosylated in insect cells and could be purified in the absence of detergents by affinity chromatography using the anti-H-2Kd monoclonal antibody SF1.1.1.1. We tested the ability of SC-Kd to bind antigenic peptides using a direct binding assay based on photoaffinity labeling. The photoreactive derivative …
Hypervirulent Chlamydia Trachomatis Clinical Strain Is A Recombinant Between Lymphogranuloma Venereum (L(2)) And D Lineages, Naraporn Somboonna, Raymond Wan, David M. Ojcius, Matthew A. Pettengill, Sandeep J. Joseph, Alexander Chang, Ray Hsu, Timothy D. Read, Deborah Dean
Hypervirulent Chlamydia Trachomatis Clinical Strain Is A Recombinant Between Lymphogranuloma Venereum (L(2)) And D Lineages, Naraporn Somboonna, Raymond Wan, David M. Ojcius, Matthew A. Pettengill, Sandeep J. Joseph, Alexander Chang, Ray Hsu, Timothy D. Read, Deborah Dean
David M. Ojcius
Chlamydia trachomatis is an obligate intracellular bacterium that causes a diversity of severe and debilitating diseases worldwide. Sporadic and ongoing outbreaks of lymphogranuloma venereum (LGV) strains among men who have sex with men (MSM) support the need for research on virulence factors associated with these organisms. Previous analyses have been limited to single genes or genomes of laboratory-adapted reference strain L2/434 and outbreak strain L2b/UCH-1/proctitis. We characterized an unusual LGV strain, termed L2c, isolated from an MSM with severe hemorrhagic proctitis. L2c developed nonfusing, grape-like inclusions and a cytotoxic phenotype in culture, unlike the LGV strains described to date. Deep …
Identification Of Cd24 As A Cancer Stem Cell Marker In Human Nasopharyngeal Carcinoma, Chun-Hung Yang, Hui-Ling Wang, Yi-Sheng Lin, K. P. Shravan Kumar, Hung-Chi Lin, Chih-Jung Chang, Chia-Chen Lu, Tsung-Teng Huang, Jan Martel, David M. Ojcius, Yu-Sun Chang, John Ding-E. Young, Hsin-Chih Lai
Identification Of Cd24 As A Cancer Stem Cell Marker In Human Nasopharyngeal Carcinoma, Chun-Hung Yang, Hui-Ling Wang, Yi-Sheng Lin, K. P. Shravan Kumar, Hung-Chi Lin, Chih-Jung Chang, Chia-Chen Lu, Tsung-Teng Huang, Jan Martel, David M. Ojcius, Yu-Sun Chang, John Ding-E. Young, Hsin-Chih Lai
David M. Ojcius
Cancer stem cells (CSCs) represent a unique sub-population of tumor cells with the ability to initiate tumor growth and sustain self-renewal. Although CSC biomarkers have been described for various tumors, only a few markers have been identified for nasopharyngeal carcinoma (NPC). In this study, we show that CD24+ cells isolated from human NPC cell lines express stem cell genes (Sox2, Oct4, Nanog, Bmi-1, and Rex-1), and show activation of the Wnt/β-catenin signaling pathway. CD24+ cells possess typical CSC characteristics that include enhanced cell proliferation, increased colony and sphere formation, maintenance of cell differentiation potential in prolonged culture, and enhanced resistance …
Hirsutella Sinensis Mycelium Attenuates Bleomycin-Induced Pulmonary Inflammation And Fibrosis In Vivo, Tsung-Teng Huang, Hsin-Chih Lai, Yun-Fei Ko, David M. Ojcius, Ying-Wei Lan, Jan Martel, John Ding-E. Young, Kowit-Yu Chong
Hirsutella Sinensis Mycelium Attenuates Bleomycin-Induced Pulmonary Inflammation And Fibrosis In Vivo, Tsung-Teng Huang, Hsin-Chih Lai, Yun-Fei Ko, David M. Ojcius, Ying-Wei Lan, Jan Martel, John Ding-E. Young, Kowit-Yu Chong
David M. Ojcius
Hirsutella sinensis mycelium (HSM), the anamorph of Cordyceps sinensis, is a traditional Chinese medicine that has been shown to possess various pharmacological properties. We previously reported that this fungus suppresses interleukin-1β and IL-18 secretion by inhibiting both canonical and non-canonical inflammasomes in human macrophages. However, whether HSM may be used to prevent lung fibrosis and the mechanism underlying this activity remain unclear. Our results show that pretreatment with HSM inhibits TGF-β1–induced expression of fibronectin and α-SMA in lung fibroblasts. HSM also restores superoxide dismutase expression in TGF-β1–treated lung fibroblasts and inhibits reactive oxygen species production in lung epithelial cells. Furthermore, …
Hepatitis C Virus Frameshift/Alternate Reading Frame Protein Suppresses Interferon Responses Mediated By Pattern Recognition Receptor Retinoic-Acid-Inducible Gene-I, Seung Bum Park, Scott Seronello, Wasima Mayer, David M. Ojcius
Hepatitis C Virus Frameshift/Alternate Reading Frame Protein Suppresses Interferon Responses Mediated By Pattern Recognition Receptor Retinoic-Acid-Inducible Gene-I, Seung Bum Park, Scott Seronello, Wasima Mayer, David M. Ojcius
David M. Ojcius
Hepatitis C virus (HCV) actively evades host interferon (IFN) responses but the mechanisms of how it does so are not completely understood. In this study, we present evidence for an HCV factor that contributes to the suppression of retinoic-acid-inducible gene-I (RIG-I)-mediated IFN induction. Expression of frameshift/alternate reading frame protein (F/ARFP) from HCV -2/+1 frame in Huh7 hepatoma cells suppressed type I IFN responses stimulated by HCV RNA pathogen-associated molecular pattern (PAMP) and poly(IC). The suppression occurred independently of other HCV factors; and activation of interferon stimulated genes, TNFα, IFN-λ1, and IFN-λ2/3 was likewise suppressed by HCV F/ARFP. Point mutations in …
Identification Of Leptospira Interrogans Phospholipase C As A Novel Virulence Factor Responsible For Intracellular Free Calcium Ion Elevation During Macrophage Death, Jing-Fang Zhao, Hong-Hu Chen, David M. Ojcius, Xin Zhao, Dexter Sun, Yu-Mei Ge, Lin-Li Zheng, Xu'ai Lin, Lan-Juan Li, Jie Yan
Identification Of Leptospira Interrogans Phospholipase C As A Novel Virulence Factor Responsible For Intracellular Free Calcium Ion Elevation During Macrophage Death, Jing-Fang Zhao, Hong-Hu Chen, David M. Ojcius, Xin Zhao, Dexter Sun, Yu-Mei Ge, Lin-Li Zheng, Xu'ai Lin, Lan-Juan Li, Jie Yan
David M. Ojcius
Background: Leptospira-induced macrophage death has been confirmed to play a crucial role in pathogenesis of leptospirosis, a worldwide zoonotic infectious disease. Intracellular free Ca2+ concentration ([Ca2+]i) elevation induced by infection can cause cell death, but [Ca2+]i changes and high [Ca2+]i-induced death of macrophages due to infection of Leptospira have not been previously reported. Methodology/Principal Findings: We first used a Ca2+-specific fluorescence probe to confirm that the infection of L. interrogans strain Lai triggered a significant increase of [Ca2+]i in mouse J774A.1 or human THP-1 macrophages. Laser confocal microscopic examination showed that the [Ca2+]i elevation was caused by both extracellular Ca2+ …
Hirsutella Sinensis Mycelium Suppresses Interleukin-1b And Interleukin-18 Secretion By Inhibiting Both Canonical And Non-Canonical Inflammasomes, Tsung-Teng Huang, Kowit-Yu Chong, David M. Ojcius, Yi-Hui Wu, Yun-Fei Ko, Cheng-Yeu Wu, Jan Martel, Chia-Chen Lu, Hsin-Chih Lai, John Ding-E. Young
Hirsutella Sinensis Mycelium Suppresses Interleukin-1b And Interleukin-18 Secretion By Inhibiting Both Canonical And Non-Canonical Inflammasomes, Tsung-Teng Huang, Kowit-Yu Chong, David M. Ojcius, Yi-Hui Wu, Yun-Fei Ko, Cheng-Yeu Wu, Jan Martel, Chia-Chen Lu, Hsin-Chih Lai, John Ding-E. Young
David M. Ojcius
Cordyceps sinensis is a medicinal mushroom used for centuries in Asian countries as a health supplement and tonic. Hirsutella sinensis—the anamorphic, mycelial form of C. sinensis—possesses similar properties, and is increasingly used as a health supplement. Recently, C. sinensis extracts were shown to inhibit the production of the pro-inflammatory cytokine IL-1β in lipopolysaccharide-treated macrophages. However, the molecular mechanism underlying this process has remained unclear. In addition, whether H. sinensis mycelium (HSM) extracts also inhibit the production of IL-1β has not been investigated. In the present study, the HSM extract suppresses IL-1β and IL-18 secretion, and ATP-induced activation of caspase-1. Notably, …
Extracellular Atp Acts On P2y2 Purinergic Receptors To Facilitate Hiv-1 Infection, Claire Séror, Marie-Therese Melki, Frederic Subra, Syed Qasim Raza, Marlene Bras, Hela Saïdi, Roberta Nardacci, Laurent Voisin, Audrey Paoletti, Frederic Law, Isabelle Martins, Alessandra Amendola, Ali A. Abdul-Sater, Fabiola Ciccosanti, Olivier Delelis, Florence Niedergang, Sylvain Thierry, Najwane Said-Sadier, Christophe Lamaze, Didier Métivier, Jerome Estaquier, Gian Maria Fimia, Laura Falasca, Rita Casetti, Nazanine Modjtahedi, Jean M. Kanellopoulos, Jean-Francois Mouscadet, David M. Ojcius, Mauro Piacentini, Marie-Lise Gougeon, Guido Kroemer, Jean-Luc Perfetini
Extracellular Atp Acts On P2y2 Purinergic Receptors To Facilitate Hiv-1 Infection, Claire Séror, Marie-Therese Melki, Frederic Subra, Syed Qasim Raza, Marlene Bras, Hela Saïdi, Roberta Nardacci, Laurent Voisin, Audrey Paoletti, Frederic Law, Isabelle Martins, Alessandra Amendola, Ali A. Abdul-Sater, Fabiola Ciccosanti, Olivier Delelis, Florence Niedergang, Sylvain Thierry, Najwane Said-Sadier, Christophe Lamaze, Didier Métivier, Jerome Estaquier, Gian Maria Fimia, Laura Falasca, Rita Casetti, Nazanine Modjtahedi, Jean M. Kanellopoulos, Jean-Francois Mouscadet, David M. Ojcius, Mauro Piacentini, Marie-Lise Gougeon, Guido Kroemer, Jean-Luc Perfetini
David M. Ojcius
Extracellular adenosine triphosphate (ATP) can activate purinergic receptors of the plasma membrane and modulate multiple cellular functions. We report that ATP is released from HIV-1 target cells through pannexin-1 channels upon interaction between the HIV-1 envelope protein and specific target cell receptors. Extracellular ATP then acts on purinergic receptors, including P2Y2, to activate proline-rich tyrosine kinase 2 (Pyk2) kinase and transient plasma membrane depolarization, which in turn stimulate fusion between Env-expressing membranes and membranes containing CD4 plus appropriate chemokine co-receptors. Inhibition of any of the constituents of this cascade (pannexin-1, ATP, P2Y2, and Pyk2) impairs the replication of HIV-1 mutant …