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Rowaiye AB, Ogugua AJ, Ibeanu G, Bur D, Asala MT, Ogbeide OB, Abraham EO, Usman HB. Identifying potential natural inhibitors of Brucella melitensis Methionyl-tRNA synthetase through an in-silico approach. PLoS Negl Trop Dis 2022; 16:e0009799. [PMID: 35312681 PMCID: PMC8970508 DOI: 10.1371/journal.pntd.0009799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 03/31/2022] [Accepted: 02/16/2022] [Indexed: 12/12/2022] Open
Abstract
Background Brucellosis is an infectious disease caused by bacteria of the genus Brucella. Although it is the most common zoonosis worldwide, there are increasing reports of drug resistance and cases of relapse after long term treatment with the existing drugs of choice. This study therefore aims at identifying possible natural inhibitors of Brucella melitensis Methionyl-tRNA synthetase through an in-silico approach. Methods Using PyRx 0.8 virtual screening software, the target was docked against a library of natural compounds obtained from edible African plants. The compound, 2-({3-[(3,5-dichlorobenzyl) amino] propyl} amino) quinolin-4(1H)-one (OOU) which is a co-crystallized ligand with the target was used as the reference compound. Screening of the molecular descriptors of the compounds for bioavailability, pharmacokinetic properties, and bioactivity was performed using the SWISSADME, pkCSM, and Molinspiration web servers respectively. The Fpocket and PLIP webservers were used to perform the analyses of the binding pockets and the protein ligand interactions. Analysis of the time-resolved trajectories of the Apo and Holo forms of the target was performed using the Galaxy and MDWeb servers. Results The lead compounds, Strophanthidin and Isopteropodin are present in Corchorus olitorius and Uncaria tomentosa (Cat’s-claw) plants respectively. Isopteropodin had a binding affinity score of -8.9 kcal / ml with the target and had 17 anti-correlating residues in Pocket 1 after molecular dynamics simulation. The complex formed by Isopteropodin and the target had a total RMSD of 4.408 and a total RMSF of 9.8067. However, Strophanthidin formed 3 hydrogen bonds with the target at ILE21, GLY262 and LEU294, and induced a total RMSF of 5.4541 at Pocket 1. Conclusion Overall, Isopteropodin and Strophanthidin were found to be better drug candidates than OOU and they showed potentials to inhibit the Brucella melitensis Methionyl-tRNA synthetase at Pocket 1, hence abilities to treat brucellosis. In-vivo and in-vitro investigations are needed to further evaluate the efficacy and toxicity of the lead compounds. The cure for brucellosis involves a long course of treatment with a combination of antibiotics. However, some of the drugs are not recommended for very young children and pregnant women. Moreover, cases of relapse and resistance to these drugs are reported. With the Brucella Methionyl-tRNA synthetase as a target, molecular docking and virtual screening was used to identify possible drug candidates from a library of 1524 compounds obtained from edible African plants. Two lead compounds, Strophanthidin and Isopteropodin usually present in Corchorus olitorius and Uncaria tomentosa (Cat’s claw) plants showed potentials to inhibit the Brucella melitensis Methionyl-tRNA synthetase. Their bioactivities were also confirmed in their molecular dynamic simulation with the target protein. Consequently, both compounds have potentials for safety and efficacy in the treatment of brucellosis.
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Affiliation(s)
| | - Akwoba Joseph Ogugua
- Department of Veterinary Public Health and Preventive Medicine, University of Nigeria, Nsukka, Nigeria
- * E-mail:
| | - Gordon Ibeanu
- Department of Pharmaceutical Science, North Carolina Central University, Durham, North Carolina, United States of America
| | - Doofan Bur
- Department of Medical Biotechnology, National Biotechnology Development Agency, Abuja, Nigeria
| | - Mercy Titilayo Asala
- Department of Medical Biotechnology, National Biotechnology Development Agency, Abuja, Nigeria
| | | | | | - Hamzah Bundu Usman
- Department of Plant Science and Biotechnology, Federal University Gusau, Gusau, Nigeria
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Immune-metabolic receptor GPR84 surrogate and endogenous agonists, 6-OAU and lauric acid, alter Brucella abortus 544 infection in both in vitro and in vivo systems. Microb Pathog 2021; 158:105079. [PMID: 34245824 DOI: 10.1016/j.micpath.2021.105079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 01/18/2023]
Abstract
Brucella abortus, one of the most important members of the genus Brucella responsible for human disease, is an intracellular pathogen capable of avoiding or interfering components of the host immune responses that are critical for its virulence. GPR84, on the other hand, is a seven-transmembrane GPCR involved in the inflammatory response and its induced expression was associated with B. abortus infection of RAW264.7 cells. Here we examined the effects of the reported GPR84 surrogate and endogenous agonists, namely 6-n-octylaminouracil (6-OAU) and lauric acid (LU), respectively in the progression of B. abortus infection in a cell and mouse models. The in vitro studies revealed the LU had bactericidal effect against Brucella starting at 24 h post-incubation. Adhesion of Brucella to RAW264.7 cells was attenuated in both 6-OAU and LU treatments. Brucella uptake was observed to be inhibited in a dose and time-dependent manner in 6-OAU but only at the highest non-cytotoxic concentration in LU-treated cells. However, survival of Brucella within the cells was reduced only in LU-treated cells. We also investigated the possible inhibitory effects of the agonist in other Gram-negative bacterium, Salmonella Typhimurium and we found that both adhesion and uptake were inhibited in 6-OAU treatment and only the intracellular survival for LU treatment. Furthermore, 6-OAU treatment reduced ERK phosphorylation and MCP-1 secretion during Brucella infection as well as reduced MALT1 protein expression and ROS production in cells without infection. LU treatment attenuated ERK and JNK phosphorylation, MCP-1 secretion and NO accumulation but increased ROS production during infection, and similar pattern with MALT1 protein expression. The in vivo studies showed that both treatments via oral route augmented resistance to Brucella infection but more pronounced with 6-AOU as observed with reduced bacterial proliferation in spleens and livers. At 7 d post-treatment and 14 d post-infection, 6-OAU-treated mice displayed reduced IFN-γ serum level. At 7 d post-infection, high serum level of MCP-1 was observed in both treatments with the addition of TNF-α in LU group. IL-6 was increased in both treatments at 14 d post-infection with higher TNF-α, MCP-1 and IL-10 in LU group. Taken together, 6-OAU and LU are potential candidates representing pharmaceutical strategy against brucellosis and possibly other intracellular pathogens or inflammatory diseases.
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Basu M, Gupta P, Dutta A, Jana K, Ukil A. Increased host ATP efflux and its conversion to extracellular adenosine is crucial for establishing Leishmania infection. J Cell Sci 2020; 133:jcs239939. [PMID: 32079656 DOI: 10.1242/jcs.239939] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 02/07/2020] [Indexed: 12/19/2022] Open
Abstract
Intracellular survival of Leishmania donovani demands rapid production of host ATP for its sustenance. However, a gradual decrease in intracellular ATP in spite of increased glycolysis suggests ATP efflux during infection. Accordingly, upon infection, we show here that ATP is exported and the major exporter was pannexin-1, leading to raised extracellular ATP levels. Extracellular ATP shows a gradual decrease after the initial increase, and analysis of cell surface ATP-degrading enzymes revealed induction of the ectonucleotidases CD39 and CD73. Ectonucleotidase-mediated ATP degradation leads to increased extracellular adenosine (eADO), and inhibition of CD39 and CD73 in infected cells decreased adenosine concentration and parasite survival, documenting the importance of adenosine in infection. Inhibiting adenosine uptake by cells did not affect parasite survival, suggesting that eADO exerts its effect through receptor-mediated signalling. We also show that Leishmania induces the expression of adenosine receptors A2AR and A2BR, both of which are important for anti-inflammatory responses. Treating infected BALB/c mice with CD39 and CD73 inhibitors resulted in decreased parasite burden and increased host-favourable cytokine production. Collectively, these observations indicate that infection-induced ATP is exported, and after conversion into adenosine, propagates infection via receptor-mediated signalling.
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Affiliation(s)
- Moumita Basu
- Department of Biochemistry, University of Calcutta, Kolkata 700019, West Bengal, India
| | - Purnima Gupta
- Infections and Cancer Biology Group, International Agency for Research on Cancer, 69372, Lyon Cedex 08, France
| | - Ananya Dutta
- Division of Molecular Medicine, Bose Institute, P1/12 Calcutta Improvement Trust Scheme, VIIM, Kolkata, 700054, West Bengal, India
| | - Kuladip Jana
- Division of Molecular Medicine, Bose Institute, P1/12 Calcutta Improvement Trust Scheme, VIIM, Kolkata, 700054, West Bengal, India
| | - Anindita Ukil
- Department of Biochemistry, University of Calcutta, Kolkata 700019, West Bengal, India
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Escherichia coli O157:H7 suppresses host autophagy and promotes epithelial adhesion via Tir-mediated and cAMP-independent activation of protein kinase A. Cell Death Discov 2017; 3:17055. [PMID: 28975041 PMCID: PMC5624281 DOI: 10.1038/cddiscovery.2017.55] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 07/07/2017] [Indexed: 11/18/2022] Open
Abstract
Autophagy is a pivotal innate immune response that not only degrades cytosolic components, but also serves as one of the critical antimicrobial mechanisms eliminating intracellular pathogens. However, its role in host defense against extracellular pathogens is largely unknown. Here we showed that E. coli O157:H7 altered autophagy to evade host defense and facilitate adhesion. Enhancing host cell autophagy with tumor necrosis factor (TNF), host starvation or rapamycin reduced the adherence of E. coli O157:H7 to HT-29 cells. As a key regulator of autophagy, protein kinase A (PKA) was activated by E. coli O157:H7 infection. PKA inhibition by H89 abrogated E. coli O157:H7 inhibition of autophagy and prevented bacterial epithelial adhesion. Thus, PKA had a mediatory role in blocking autophagy and E. coli O157:H7 epithelial adhesion. Furthermore, deletion of translocated intimin receptor (tir) prevented PKA activation, whereas ectopic tir expression in a Δtir mutant strain restored its ability to activate PKA and inhibited autophagy in host cells. This indicated that Tir and PKA played pivotal roles in manipulating host autophagy during infection. Consistent with autophagy inhibition, E. coli O157:H7 infection inhibited endoplasmic reticulum (ER) stress in HT-29 cells, which was reversed by TNF, starvation, or H89 treatment. Additionally, E. coli O157:H7-induced PKA activation suppressed extracellular signal-regulated kinase 1/2 (ERK1/2) activation and enhanced phosphatidylinositol 3-kinase/Akt (PI3K/Akt) signaling, thereby repressing autophagic signaling. Conversely, PKA inhibition prevented downregulation of ERK1/2 signaling due to E. coli O157:H7 infection. In summary, E. coli O157:H7 inhibited host autophagy via Tir-mediated PKA activation that favored bacterial persistence on intestinal epithelial cell surfaces.
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Richter E, Harms M, Ventz K, Nölker R, Fraunholz MJ, Mostertz J, Hochgräfe F. Quantitative Proteomics Reveals the Dynamics of Protein Phosphorylation in Human Bronchial Epithelial Cells during Internalization, Phagosomal Escape, and Intracellular Replication of Staphylococcus aureus. J Proteome Res 2016; 15:4369-4386. [DOI: 10.1021/acs.jproteome.6b00421] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Erik Richter
- Competence
Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, 17489 Greifswald, Germany
| | - Manuela Harms
- Competence
Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, 17489 Greifswald, Germany
| | - Katharina Ventz
- Competence
Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, 17489 Greifswald, Germany
| | - Rolf Nölker
- Competence
Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, 17489 Greifswald, Germany
| | | | - Jörg Mostertz
- Competence
Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, 17489 Greifswald, Germany
| | - Falko Hochgräfe
- Competence
Center Functional Genomics, Junior Research Group Pathoproteomics, University of Greifswald, 17489 Greifswald, Germany
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Saha A, Biswas A, Srivastav S, Mukherjee M, Das PK, Ukil A. Prostaglandin E2 negatively regulates the production of inflammatory cytokines/chemokines and IL-17 in visceral leishmaniasis. THE JOURNAL OF IMMUNOLOGY 2014; 193:2330-9. [PMID: 25049356 DOI: 10.4049/jimmunol.1400399] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Persistence of intracellular infection depends on the exploitation of factors that negatively regulate the host immune response. In this study, we elucidated the role of macrophage PGE2, an immunoregulatory lipid, in successful survival of Leishmania donovani, causative agent of the fatal visceral leishmaniasis. PGE2 production was induced during infection and resulted in increased cAMP level in peritoneal macrophages through G protein-coupled E-series prostanoid (EP) receptors. Among four different EPs (EP1-4), infection upregulated the expression of only EP2, and individual administration of either EP2-specific agonist, butaprost, or 8-Br-cAMP, a cell-permeable cAMP analog, promoted parasite survival. Inhibition of cAMP also induced generation of reactive oxygen species, an antileishmanial effector molecule. Negative modulation of PGE2 signaling reduced infection-induced anti-inflammatory cytokine polarization and enhanced inflammatory chemokines, CCL3 and CCL5. Effect of PGE2 on cytokine and chemokine production was found to be differentially modulated by cAMP-dependent protein kinase A (PKA) and exchange protein directly activated by cAMP (EPAC). PGE2-induced decreases in TNF-α and CCL5 were mediated specifically by PKA, whereas administration of brefeldin A, an EPAC inhibitor, could reverse decreased production of CCL3. Apart from modulating inflammatory/anti-inflammatory balance, PGE2 inhibited antileishmanial IL-17 cytokine production in splenocyte culture. Augmented PGE2 production was also found in splenocytes of infected mice, and administration of EP2 antagonist in mice resulted in reduced liver and spleen parasite burden along with host-favorable T cell response. These results suggest that Leishmania facilitates an immunosuppressive environment in macrophages by PGE2-driven, EP2-mediated cAMP signaling that is differentially regulated by PKA and EPAC.
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Affiliation(s)
- Amrita Saha
- Department of Biochemistry, University of Calcutta, Kolkata 700019, India; and
| | - Arunima Biswas
- Infectious Diseases and Immunology Division, Council of Scientific & Industrial Research-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Supriya Srivastav
- Infectious Diseases and Immunology Division, Council of Scientific & Industrial Research-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Madhuchhanda Mukherjee
- Infectious Diseases and Immunology Division, Council of Scientific & Industrial Research-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Pijush K Das
- Infectious Diseases and Immunology Division, Council of Scientific & Industrial Research-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Anindita Ukil
- Department of Biochemistry, University of Calcutta, Kolkata 700019, India; and
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Role of calmodulin-calmodulin kinase II, cAMP/protein kinase A and ERK 1/2 on Aeromonas hydrophila-induced apoptosis of head kidney macrophages. PLoS Pathog 2014; 10:e1004018. [PMID: 24763432 PMCID: PMC3999153 DOI: 10.1371/journal.ppat.1004018] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 02/05/2014] [Indexed: 01/06/2023] Open
Abstract
The role of calcium (Ca2+) and its dependent protease calpain in Aeromonas hydrophila-induced head kidney macrophage (HKM) apoptosis has been reported. Here, we report the pro-apoptotic involvement of calmodulin (CaM) and calmodulin kinase II gamma (CaMKIIg) in the process. We observed significant increase in CaM levels in A. hydrophila-infected HKM and the inhibitory role of BAPTA/AM, EGTA, nifedipine and verapamil suggested CaM elevation to be Ca2+-dependent. Our studies with CaM-specific siRNA and the CaM inhibitor calmidazolium chloride demonstrated CaM to be pro-apoptotic that initiated the downstream expression of CaMKIIg. Using the CaMKIIg-targeted siRNA, specific inhibitor KN-93 and its inactive structural analogue KN-92 we report CaM-CaMKIIg signalling to be critical for apoptosis of A. hydrophila-infected HKM. Inhibitor studies further suggested the role of calpain-2 in CaMKIIg expression. CaMK Kinase (CaMKK), the other CaM dependent kinase exhibited no role in A. hydrophila-induced HKM apoptosis. We report increased production of intracellular cAMP in infected HKM and our results with KN-93 or KN-92 implicate the role of CaMKIIg in cAMP production. Using siRNA to PKACA, the catalytic subunit of PKA, anti-PKACA antibody and H-89, the specific inhibitor for PKA we prove the pro-apoptotic involvement of cAMP/PKA pathway in the pathogenicity of A. hydrophila. Our inhibitor studies coupled with siRNA approach further implicated the role of cAMP/PKA in activation of extracellular signal-regulated kinase 1 and 2 (ERK 1/2). We conclude that the alteration in intracellular Ca2+ levels initiated by A. hydrophila activates CaM and calpain-2; both pathways converge on CaMKIIg which in turn induces cAMP/PKA mediated ERK 1/2 phosphorylation leading to caspase-3 mediated apoptosis of infected HKM. Aeromonas hydrophila is a natural fish pathogen and is known to induce apoptosis of HKM. Head kidney is an important immune-organ in fish and HKM are critical for immunity against the invading pathogen. The mechanisms of cell death induced by A. hydrophila are incompletely characterized. We have studied the role of Ca2+-dependent signalling pathways in the induction of A. hydrophila-induced HKM apoptosis. We observed that A. hydrophila infection led to increased CaM expression in infected HKM which was Ca2+-dependent. The inhibitor and siRNA studies suggested CaM to be pro-apoptotic and triggered CaMKIIg expression in the infected HKM. Calpain-2 appeared to influence CaMKIIg expression. However, further studies are needed to understand the process. We report that the CaM-CaMKIIg pathway is important for initiating cAMP production within the infected HKM. The pro-apoptotic activation of cAMP dependent PKA was quite evident. The activation of ERK 1/2 was observed in the HKM and results clearly suggested the pro-active role of cAMP/PKA in the process. Thus we conclude that CaM-CaMKIIg initiates the cAMP/PKA pathway that induces ERK 1/2 phosphorylation to promote caspase-3 mediated apoptosis of the A. hydrophila-infected HKM.
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Coxiella burnetii alters cyclic AMP-dependent protein kinase signaling during growth in macrophages. Infect Immun 2012; 80:1980-6. [PMID: 22473604 DOI: 10.1128/iai.00101-12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coxiella burnetii is the bacterial agent of human Q fever, an acute, flu-like illness that can present as chronic endocarditis in immunocompromised individuals. Following aerosol-mediated transmission, C. burnetii replicates in alveolar macrophages in a unique phagolysosome-like parasitophorous vacuole (PV) required for survival. The mechanisms of C. burnetii intracellular survival are poorly defined and a recent Q fever outbreak in the Netherlands emphasizes the need for better understanding this unique host-pathogen interaction. We recently demonstrated that inhibition of host cyclic AMP-dependent protein kinase (PKA) activity negatively impacts PV formation. In the current study, we confirmed PKA involvement in PV biogenesis and probed the role of PKA signaling during C. burnetii infection of macrophages. Using PKA-specific inhibitors, we found the kinase was needed for biogenesis of prototypical PV and C. burnetii replication. PKA and downstream targets were differentially phosphorylated throughout infection, suggesting prolonged regulation of the pathway. Importantly, the pathogen actively triggered PKA activation, which was also required for PV formation by virulent C. burnetii isolates during infection of primary human alveolar macrophages. A subset of PKA-specific substrates were differentially phosphorylated during C. burnetii infection, suggesting the pathogen uses PKA signaling to control distinct host cell responses. Collectively, the current results suggest a versatile role for PKA in C. burnetii infection and indicate virulent organisms usurp host kinase cascades for efficient intracellular growth.
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Kim DH, Lim JJ, Lee JJ, Kim DG, Lee HJ, Min W, Kim KD, Chang HH, Endale M, Rhee MH, Watarai M, Kim S. RGS2-Mediated Intracellular Ca2+ Level Plays a Key Role in the Intracellular Replication of Brucella abortus Within Phagocytes. J Infect Dis 2011; 205:445-52. [DOI: 10.1093/infdis/jir765] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Bai G, Schaak DD, Smith EA, McDonough KA. Dysregulation of serine biosynthesis contributes to the growth defect of a Mycobacterium tuberculosis crp mutant. Mol Microbiol 2011; 82:180-98. [PMID: 21902733 DOI: 10.1111/j.1365-2958.2011.07806.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mycobacterium tuberculosis CRP(Mt), encoded by Rv3676 (crp), is a CRP-like transcription factor that binds with the serC-Rv0885 intergenic region. In the present study, we evaluated CRP(Mt) 's regulation of serC and Rv0885 in M. tuberculosis and M. bovis BCG, using site-specific mutagenesis, promoter fusions and reverse-transcriptase PCR (RT-PCR). The CRP(Mt) binding site was required for full expression of serC and Rv0885, and expression of both genes was reduced in M. tuberculosis and M. bovis BCG crp mutants. These data show that CRP(Mt) binding directly activates both serC and Rv0885 expression. M. tuberculosis serC restored the ability of an Escherichia coli serC mutant to grow in serine-dropout medium, demonstrating that M. tuberculosis serC encodes a phosphoserine aminotransferase. Serine supplementation, or overexpression of serC, accelerated the growth of M. tuberculosis and M. bovis BCG crp mutants in mycomedium, but not within macrophages. These results establish a role for CRP(Mt) in the regulation of amino acid biosynthesis, and show that reduced serine production contributes to the slow-growth phenotype of M. tuberculosis and M. bovis BCG crp mutants in vitro. Restoration of serine biosynthesis by serC expression will facilitate identification of additional CRP(Mt)-regulated factors required by M. tuberculosis during macrophage and host infection.
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Affiliation(s)
- Guangchun Bai
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, PO Box 22002, Albany, NY 12201-2002, USA
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Hussain SK, Broederdorf LJ, Sharma UM, Voth DE. Host Kinase Activity is Required for Coxiella burnetii Parasitophorous Vacuole Formation. Front Microbiol 2010; 1:137. [PMID: 21772829 PMCID: PMC3119423 DOI: 10.3389/fmicb.2010.00137] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 12/04/2010] [Indexed: 11/24/2022] Open
Abstract
Coxiella burnetii is the etiologic agent of human Q fever and targets alveolar phagocytic cells in vivo wherein the pathogen generates a phagolysosome-like parasitophorous vacuole (PV) for replication. C. burnetii displays a prolonged growth cycle, making PV maintenance critical for bacterial survival. Previous studies showed that C. burnetii mediates activation of eukaryotic kinases to inhibit cell death, indicating the importance of host signaling during infection. In the current study, we examined the role of eukaryotic kinase signaling in PV establishment. A panel of 113 inhibitors was analyzed for their impact on C. burnetii infection of human THP-1 macrophage-like cells and HeLa cells. Inhibition of 11 kinases or two phosphatases altered PV formation and prevented pathogen growth, with most inhibitor-treated cells harboring organisms in tight-fitting phagosomes, indicating kinase/phosphatase activation is required for PV maturation. Five inhibitors targeted protein kinase C (PKC), suggesting a critical role for this protein during intracellular growth. The PKC-specific substrate MARCKS was phosphorylated at 24 h post-infection and remained phosphorylated through 5 days post-infection, indicating prolonged regulation of the PKC pathway by C. burnetii. Infection also altered the activation status of p38, myosin light chain kinase, and cAMP-dependent protein kinase, suggesting C. burnetii subverts numerous phosphorylation cascades. These results underscore the importance of intracellular host signaling for C. burnetii PV biogenesis.
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Affiliation(s)
- S Kauser Hussain
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences Little Rock, AR, USA
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Skendros P, Pappas G, Boura P. Cell-mediated immunity in human brucellosis. Microbes Infect 2010; 13:134-42. [PMID: 21034846 DOI: 10.1016/j.micinf.2010.10.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/13/2010] [Accepted: 10/15/2010] [Indexed: 01/18/2023]
Abstract
Brucella can parasitize within human antigen-presenting cells modifying phagocytosis, phagolysosome fusion, antigen presentation, cytokine secretion, and apoptosis. Subversion of innate immune mechanisms by Brucella leads to defective Th1 immune responses and T-cell anergy in chronic brucellosis patients. This review summarizes the cellular immune responses in brucellosis, based on data derived exclusively from human cells or cell lines.
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Affiliation(s)
- Panagiotis Skendros
- First Department of Internal Medicine, Democritus University of Thrace, Alexandroupolis, Greece.
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Gazdik MA, Bai G, Wu Y, McDonough KA. Rv1675c (cmr) regulates intramacrophage and cyclic AMP-induced gene expression in Mycobacterium tuberculosis-complex mycobacteria. Mol Microbiol 2008; 71:434-48. [PMID: 19040643 DOI: 10.1111/j.1365-2958.2008.06541.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cyclic AMP (cAMP) has recently been shown to be a global regulator of gene expression in Mycobacterium tuberculosis (Mtb). In this study we identified a new cAMP-associated regulon in Mtb and Mycobacterium bovis BCG, which is distinct from the previously described CRP(Mt) regulon. Proteomic comparison of wild-type M. bovis BCG with a Rv1675c (cmr) knockout strain showed dysregulated expression of four previously identified proteins encoded by the cAMP-induced genes (cAIGs) mdh, groEL2, Rv1265 and PE_PGRS6a. Regulated expression of these four cAIGs also occurred during macrophage infection, and this regulation required cmr in both Mtb and M. bovis BCG. Purified His-Cmr bound to the DNA sequences upstream of three cAIGs (mdh, groEL2, Rv1265) in electrophoretic mobility shift assays, suggesting direct regulation of these genes by Cmr. We also found that low pH stimulated cAMP production in both Mtb and M. bovis BCG, but broadly affected cAIG regulation only in M. bovis BCG. These studies identify Cmr as a transcription factor that regulates cAIGs within macrophages, and suggest that multiple factors affect cAMP-associated gene regulation in tuberculosis-complex mycobacteria. cAMP signalling and Cmr-mediated gene regulation during Mtb infection of macrophages may have implications for TB pathogenesis.
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Affiliation(s)
- Michaela A Gazdik
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY 12201, USA
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Bouhet S, Lafont V, Billard E, Gross A, Dornand J. The IFNgamma-induced STAT1-CBP/P300 association, required for a normal response to the cytokine, is disrupted in Brucella-infected macrophages. Microb Pathog 2008; 46:88-97. [PMID: 19041714 DOI: 10.1016/j.micpath.2008.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 10/24/2008] [Accepted: 10/31/2008] [Indexed: 01/18/2023]
Abstract
To develop intracellularly within phagocytes and cause chronic infection, Brucella must overcome different steps of the host immune responses. IFNgamma is a key mediator of the innate and adaptive responses produced during Brucella infection. Therefore, Brucella would control host defenses by impairing macrophage responses to IFNgamma. We first showed that in infected human macrophages (VD3-differentiated THP-1 cells) Brucella escaped the microbicidal environment generated by IFNgamma. We then analyzed the IFNgamma-mediated signaling in Brucella-infected cells. We observed no decrease in STAT1 tyrosine or serine phosphorylation, or in dimerization of phosphorylated STAT1 (P-STAT1) and P-STAT1 translocation to the nucleus or in P-STAT1 binding to GAS, a minimal IFNgamma-response DNA sequence. In contrast, immuno-precipitation experiments indicated that the IFNgamma-mediated association of P-STAT1 with CBP/P300 transactivators was markedly reduced in infected macrophages, demonstrating that P-STAT1 was unable to normally recruit these transactivators. The host cell cAMP pathway triggered by Brucella could be responsible for this defect, CBP/P300 mobilization by phosphorylated CREB (P-CREB) disrupting the IFNgamma-induced STAT1-CBP/P300 association, required for a normal response of macrophages to IFNgamma. In any case, the inhibition of an essential protein-protein interaction probably lead to a deteriorated response to IFNgamma and thus participated in the pathogen's establishment within its host.
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Affiliation(s)
- Sandrine Bouhet
- Université Montpellier1, Centre d'étude d'Agents Pathogènes et Biotechnologies pour la Santé (CPBS), France
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15
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Interaction of Brucella suis and Brucella abortus rough strains with human dendritic cells. Infect Immun 2007; 75:5916-23. [PMID: 17938225 DOI: 10.1128/iai.00931-07] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Brucella is a facultative intracellular pathogen of various mammals and the etiological agent of brucellosis. We recently demonstrated that dendritic cells (DCs), which are critical components of adaptive immunity, are highly susceptible to Brucella infection. Furthermore, Brucella prevented the infected DCs from engaging in maturation processes and impaired their capacity to present antigen to naive T cells and to secrete interleukin-12 (IL-12). The lipopolysaccharide (LPS) phenotype is largely associated with the virulence of Brucella. Depending on whether they express the O-side chain of LPS or not, the bacteria display a smooth or rough phenotype. Rough Brucella mutants are attenuated and induce a potent protective T-cell-dependent immune response. Due to the essential role of DCs in the initiation of T-cell-dependent adaptive immune responses, it seemed pertinent to study the interaction between rough Brucella strains and human DCs. In the present paper, we report that, in contrast to smooth bacteria, infection of DCs with rough mutants of Brucella suis or Brucella abortus leads to both phenotypic and functional maturation of infected cells. Rough mutant-infected DCs then acquire the capacity to produce IL-12 and to stimulate naive CD4+ T lymphocytes. Experiments with rough and smooth purified LPS of Brucella supported the hypothesis of an indirect involvement of the O-side chain. These results provide new data concerning the role of LPS in Brucella virulence strategy and illuminate phenomena contributing to immune protection conferred by rough vaccine strains.
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16
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Bai G, Gazdik MA, Schaak DD, McDonough KA. The Mycobacterium bovis BCG cyclic AMP receptor-like protein is a functional DNA binding protein in vitro and in vivo, but its activity differs from that of its M. tuberculosis ortholog, Rv3676. Infect Immun 2007; 75:5509-17. [PMID: 17785469 PMCID: PMC2168296 DOI: 10.1128/iai.00658-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterium tuberculosis Rv3676 encodes a cyclic AMP (cAMP) receptor-like protein (CRP(Mt)) that has been implicated in global gene regulation and may play an important role during tuberculosis infection. The CRP(Mt) ortholog in Mycobacterium bovis BCG, CRP(BCG), is dysfunctional in an Escherichia coli CRP competition assay and has been proposed as a potential source of M. bovis BCG's attenuation. We compared CRP(BCG) and CRP(Mt) in vitro and in vivo, in M. bovis BCG and M. tuberculosis, to evaluate CRP(BCG)'s potential function in a mycobacterial system. Both proteins formed dimers in mycobacterial lysates, bound to the same target DNA sequences, and were similarly affected by the presence of cAMP in DNA binding assays. However, CRP(Mt) and CRP(BCG) differed in their relative affinities for specific DNA target sequences and in their susceptibilities to protease digestion. Surprisingly, CRP(BCG) DNA binding activity was stronger than that of CRP(Mt) both in vitro and in vivo, as measured by electrophoretic mobility shift and chromatin immunoprecipitation assays. Nutrient starvation-associated regulation of several CRP(Mt) regulon members also differed between M. bovis BCG and M. tuberculosis. We conclude that CRP(BCG) is a functional cAMP-responsive DNA binding protein with an in vivo DNA binding profile in M. bovis BCG similar to that of CRP(Mt) in M. tuberculosis. However, biologically significant functional differences may exist between CRP(BCG) and CRP(Mt) with respect to gene regulation, and this issue warrants further study.
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Affiliation(s)
- Guangchun Bai
- Wadsworth Center, 120 New Scotland Avenue, PO Box 22002, Albany, NY 12201-2002, USA
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17
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Palacios N, Sánchez-Franco F, Fernández M, Sánchez I, Villuendas G, Cacicedo L. Opposite effects of two PKA inhibitors on cAMP inhibition of IGF-I-induced oligodendrocyte development: a problem of unspecificity? Brain Res 2007; 1178:1-11. [PMID: 17920050 DOI: 10.1016/j.brainres.2007.07.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 06/29/2007] [Accepted: 07/10/2007] [Indexed: 11/24/2022]
Abstract
The stimulatory effect of insulin-like growth factor I (IGF-I) on myelin basic protein (MBP) expression, a parameter for oligodendrocyte development, is mediated by the MAPK and PI3K signaling pathways. We have previously shown that the second messenger cAMP inhibits IGF-I-induced MAPK activation as well as MBP expression. We also showed that the PKA inhibitor Rp-cAMPS reverted the cAMP effect on IGF-I-induced MBP without affecting the cAMP effect on IGF-I-induced MAPK activation. Here we report that, in contrast to Rp-cAMPS, H89 (a PKA inhibitor structurally non-related to Rp-cAMPS) enhances both the inhibitory effect of cAMP on IGF-I-induced MBP expression and the inhibitory effect of cAMP on IGF-I-induced MAPK activation. Likewise, H89 is capable of inhibiting the IGF-I-induced MAPK activation in the absence of PKA stimulation. Thus, we hypothesize that an unspecific action of H89 on a target located upstream MAPK could account for the discrepancies between the effects elicited by Rp-cAMPS and H89.
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Affiliation(s)
- Nuria Palacios
- Endocrinology Department, Hospital Ramón y Cajal, Carretera de Colmenar, Km 9, 28034 Madrid, Spain
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18
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Medina-Kauwe LK. "Alternative" endocytic mechanisms exploited by pathogens: new avenues for therapeutic delivery? Adv Drug Deliv Rev 2007; 59:798-809. [PMID: 17707545 PMCID: PMC2040389 DOI: 10.1016/j.addr.2007.06.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 06/12/2007] [Indexed: 11/22/2022]
Abstract
Some pathogens utilize unique routes to enter cells that may evade the intracellular barriers encountered by the typical clathrin-mediated endocytic pathway. Retrograde transport and caveolar uptake are among the better characterized pathways, as alternatives to clathrin-mediated endocytosis, that are known to facilitate entry of pathogens and potential delivery agents. Recent characterization of the trafficking mechanisms of prion proteins and certain bacteria may present new paradigms for strategizing improvements in therapeutic spread and retention of therapy. This review will provide an overview of such endocytic pathways, and discuss current and future possibilities in using these routes as a means to improve therapeutic delivery.
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19
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Billard E, Dornand J, Gross A. Brucella suis prevents human dendritic cell maturation and antigen presentation through regulation of tumor necrosis factor alpha secretion. Infect Immun 2007; 75:4980-9. [PMID: 17635859 PMCID: PMC2044515 DOI: 10.1128/iai.00637-07] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Brucella is a facultative intracellular pathogen and the etiological agent of brucellosis. In some cases, human brucellosis results in a persistent infection that may reactivate years after the initial exposure. The mechanisms by which the parasite evades clearance by the immune response to chronically infect its host are unknown. We recently demonstrated that dendritic cells (DCs), which are critical components of adaptive immunity, are highly susceptible to Brucella infection and are a preferential niche for the development of the bacteria. Here, we report that in contrast to several intracellular bacteria, Brucella prevented the infected DCs from engaging in their maturation process and impaired their capacities to present antigen to naïve T cells and to secrete interleukin-12. Moreover, Brucella-infected DCs failed to release tumor necrosis factor alpha (TNF-alpha), a defect involving the bacterial protein Omp25. Exogenous TNF-alpha addition to Brucella-infected DCs restored cell maturation and allowed them to present antigens. Two avirulent mutants of B. suis, B. suis bvrR and B. suis omp25 mutants, which do not express the Omp25 protein, triggered TNF-alpha production upon DC invasion. Cells infected with these mutants subsequently matured and acquired the ability to present antigens, two properties which were dramatically impaired by addition of anti-TNF-alpha antibodies. In light of these data, we propose a model in which virulent Brucella alters the maturation and functions of DCs through Omp25-dependent control of TNF-alpha production. This model defines a specific evasion strategy of the bacteria by which they can escape the immune response to chronically infect their host.
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Affiliation(s)
- Elisabeth Billard
- INSERM U431, CPBS UMR CNRS 5236 UM1 UM2, F-34095 Montpellier, France
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20
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Kalamidas SA, Kuehnel MP, Peyron P, Rybin V, Rauch S, Kotoulas OB, Houslay M, Hemmings BA, Gutierrez MG, Anes E, Griffiths G. cAMP synthesis and degradation by phagosomes regulate actin assembly and fusion events: consequences for mycobacteria. J Cell Sci 2007; 119:3686-94. [PMID: 16931599 DOI: 10.1242/jcs.03091] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We showed recently that actin assembly by phagosomal membranes facilitates fusion with late endocytic organelles in macrophages. Moreover, lipids that induced phagosomal actin also stimulated this fusion process. In macrophages infected with pathogenic mycobacteria actin-stimulatory lipids led to an increase in pathogen destruction, whereas inhibitors facilitated their growth. A model was proposed whereby phagosomal membrane actin assembly provides tracks for lysosomes to move towards phagosomes, thereby facilitating fusion. Here, we investigated how cAMP affected phagosomal actin assembly in vitro, and phagosomal actin, acidification and late fusion events in J774 macrophages. Latex bead phagosomes are shown to possess adenylyl cyclase activity, which synthesizes cAMP, and phosphodiesterase activity, which degrades cAMP. The system is regulated by protein kinase A (PKA). Increasing cAMP levels inhibited, whereas decreasing cAMP levels stimulated, actin assembly in vitro and within cells. Increasing cAMP levels also inhibited phagosome-lysosome fusion and acidification in cells, whereas reducing cAMP had the opposite effect. High cAMP levels induced an increase in intraphagosomal growth in macrophages of both the non-pathogenic Mycobacterium smegmatis and the pathogenic Mycobacterium tuberculosis, whereas low cAMP levels or inhibition of PKA correlated with increased bacterial destruction. We argue that the phagosome cAMP-PKA system behaves as a molecular switch that regulates phagosome actin and maturation in macrophages.
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21
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Morjaria S, Deleuze-Masquefa C, Lafont V, Gayraud S, Bompart J, Bonnet PA, Dornand J. Impairment of TNF-alpha production and action by imidazo[1,2- alpha] quinoxalines, a derivative family which displays potential anti-inflammatory properties. Int J Immunopathol Pharmacol 2006; 19:525-38. [PMID: 17026837 DOI: 10.1177/039463200601900308] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In a previous study, we analysed the synthesis and properties of a series of imidazo[1,2-alpha]quinoxalines designed in our laboratory as possible imiquimod analogues. We found that these imidazo[1,2-alpha]quinoxalines were in fact potent inhibitors of phosphodiesterase 4 enzymes (PDE4). PDE4 inhibition normally results in an increase in intracellular cAMP which, in PBMC, induces the suppression of TNF-alpha mRNA transcription and thus cytokine synthesis. Such an effect is antagonistic to that of imiquimod. Furthermore, some TNF-alpha-induced activity, such as cell apoptosis which is dependent on the intracellular cAMP levels might also be affected. Therefore, by counteracting the properties of TNF-alpha and/or its production, the imidazo[1,2-alpha]quinoxalines could be considered as potential anti-inflammatory drugs. The present study was performed to confirm or refute this hypothesis. For this, we characterized the effects of imidazo[1,2-alpha]quinoxalines both on TNF-alpha activity and synthesis in regard to their ability to act as inhibitors of PDE4 (IPDE4). We found that the imidazo[1,2-alpha]quinoxalines dose-dependently prevented the TNF-alpha-triggered death of L929 cells, with the 8-series (-NHCH3 in R4) being the most potent. Moreover, when the effect of the 8-series on TNF-alpha production was investigated using gamma9delta2 T cells, it was observed that these compounds impaired the TCR:CD3-triggered TNF-alpha production. Structure-activity analysis revealed that these properties of the drugs did not coincide with their IPDE4 properties. This prompted further exploration into other signalling mechanisms possibly involved in TNF-alpha action and production, notably the p38 MAPK and the PI3K pathway. We demonstrate here that the imidazo[1,2-alpha]quinoxalines targeted these pathways in a different way: they activated the p38 MAPK pathway whilst inhibiting the PI3K pathway. Such effects on cell signalling could account for the imidazo[1,2-alpha]quinoxalines effects on 1) action and 2) production of TNF-alpha, which define these drugs as potential anti-inflammatory agents.
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Affiliation(s)
- S Morjaria
- INSERM U431, University of Montpellier, France
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22
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Jiménez de Bagüés MP, Loisel-Meyer S, Liautard JP, Jubier-Maurin V. Different roles of the two high-oxygen-affinity terminal oxidases of Brucella suis: Cytochrome c oxidase, but not ubiquinol oxidase, is required for persistence in mice. Infect Immun 2006; 75:531-5. [PMID: 17101669 PMCID: PMC1828397 DOI: 10.1128/iai.01185-06] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The survival of Brucella suis mutant strains in mice demonstrated different roles of the two high-oxygen-affinity terminal oxidases. The cbb3-type cytochrome c oxidase was essential for chronic infection in oxygen-deficient organs. Lack of the cytochrome bd ubiquinol oxidase led to hypervirulence of bacteria, which could rely on nitrite accumulation inhibiting the inducible nitric oxide synthase of the host.
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23
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Agarwal N, Raghunand TR, Bishai WR. Regulation of the expression of whiB1 in Mycobacterium tuberculosis: role of cAMP receptor protein. MICROBIOLOGY-SGM 2006; 152:2749-2756. [PMID: 16946269 DOI: 10.1099/mic.0.28924-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The wbl (whiB-like) genes encode putative transcription factors unique to actinomycetes. This study characterized the promoter element of one of the seven wbl genes of Mycobacterium tuberculosis, whiB1 (Rv3219c). The results reveal that whiB1 is transcribed by a class I-type cAMP receptor protein (CRP)-dependent promoter, harbouring a CRP-binding site positioned at -58.5 with respect to its transcription start point. In vivo promoter activity analysis and electrophoretic mobility shift assays suggest that the expression of whiB1 is indeed regulated by cAMP-dependent binding of CRP(M) (encoded by the M. tuberculosis gene Rv3676) to the whiB1 5' untranslated region (5'UTR). beta-Galactosidase gene fusion analysis revealed induction of the whiB1 promoter in M. tuberculosis on addition of exogenous dibutyric cAMP (a diffusible cAMP analogue) only when an intact CRP-binding site was present. These results indicate that M. tuberculosis whiB1 transcription is regulated in part by cAMP levels via direct binding of cAMP-activated CRP(M) to a consensus CRP-binding site in the whiB1 5'UTR.
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Affiliation(s)
- Nisheeth Agarwal
- Department of Medicine, Johns Hopkins University, CRB2, Rm 1.08, 1550 Orleans Street, Baltimore, MD 21231-1044, USA
| | - Tirumalai R Raghunand
- Department of Medicine, Johns Hopkins University, CRB2, Rm 1.08, 1550 Orleans Street, Baltimore, MD 21231-1044, USA
| | - William R Bishai
- Department of Medicine, Johns Hopkins University, CRB2, Rm 1.08, 1550 Orleans Street, Baltimore, MD 21231-1044, USA
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24
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Shenoy AR, Visweswariah SS. New messages from old messengers: cAMP and mycobacteria. Trends Microbiol 2006; 14:543-50. [PMID: 17055275 DOI: 10.1016/j.tim.2006.10.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 09/07/2006] [Accepted: 10/10/2006] [Indexed: 12/18/2022]
Abstract
Cyclic nucleotides are ancient second messengers, and the enzymes that synthesize cAMP and cGMP [cyclic nucleotide monophosphates (cNMPs)] are encoded in the genomes of several bacteria. We focus here on recent biochemical and structural information on the proteins that make and break cyclic nucleotides in mycobacteria, namely the nucleotide cyclases and phosphodiesterases, respectively. The presence of these enzymes along with putative cNMP-binding proteins suggests an intricate regulation of cAMP metabolism and utilization by these organisms. It is anticipated that future research will be directed towards identifying cellular processes that are regulated by cAMP in mycobacteria and deciphering the cross-talk between mycobacterial pathogens and their eukaryotic host.
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Affiliation(s)
- Avinash R Shenoy
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India
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25
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Erdogan S, Celik S, Aslantas O, Kontas T, Ocak S. Elevated cAMP levels reverse Brucella melitensis-induced lipid peroxidation and stimulate IL-10 transcription in rats. Res Vet Sci 2006; 82:181-6. [PMID: 17014875 DOI: 10.1016/j.rvsc.2006.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2006] [Revised: 07/11/2006] [Accepted: 07/19/2006] [Indexed: 11/25/2022]
Abstract
Brucella species are able to survive and replicate within the phagocytic vacuole of macrophages that induce chronic infection in humans and domestic animals. The activation of oxidative bactericidal activity is one of the defense systems which protect the host from the toxic effects of pathogens. The aim of this study was to evaluate lipid peroxidation, NO production, antioxidative system and inflammation during a period of brucella infection in a rat model; in addition to investigate the role of elevated intracellular cyclic AMP on Brucella-induced events. Brucella significantly induced lipid peroxidation in plasma, liver and spleen by 3-5-fold at 7 days postinfection. NO concentration was significantly elevated in the liver and spleen while unchanged in plasma. Cyclic AMP elevating agent, rolipram, administration (1mg/kg/day i.p., 3 days) gradually suppressed lipid peroxidation and NO formation to the basal level in plasma and spleen whilst only a slight decrease was observed in liver. Brucella considerably decreased SOD activity in the liver and spleen, with rolipram restoring the enzyme activity in liver and activity in spleen being unchanged. Reverse transcriptase PCR analyses showed that Brucella melitensis does not alter TNF-alpha and IFN-gamma transcriptions in liver and spleen. The pathogen did not consistently induce nitric oxide synthase mRNA transcriptions in animals; even in those housed in the same group. IL-10 transcription was induced by rolipram in spleen but not in liver. Our results suggest that activation of the cAMP/PKA pathway suppressed lipid peroxidation and the elevated NO concentrations caused by B. melitensis. Moreover, rolipram induced anti-inflammatory cytokine IL-10 transcription and SOD activity, albeit in a tissue dependent manner.
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Affiliation(s)
- S Erdogan
- Department of Biochemistry, Faculty of Veterinary Medicine, Mustafa Kemal University, 31034 Antakya, Turkey.
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26
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Abdel Motaal A, Tews I, Schultz JE, Linder JU. Fatty acid regulation of adenylyl cyclase Rv2212 from Mycobacterium tuberculosis H37Rv. FEBS J 2006; 273:4219-28. [PMID: 16925585 DOI: 10.1111/j.1742-4658.2006.05420.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Adenylyl cyclase Rv2212 from Mycobacterium tuberculosis has a domain composition identical to the pH-sensing isoform Rv1264, an N-terminal regulatory domain and a C-terminal catalytic domain. The maximal velocity of Rv2212 was the highest of all 10 mycobacterial cyclases investigated to date (3.9 micromol cAMP.mg(-1).min(-1)), whereas ATP substrate affinity was low (SC(50) = 2.1 mm ATP). Guanylyl cyclase side activity was absent. The activities and kinetics of the holoenzyme and of the catalytic domain alone were similar, i.e. in distinct contrast to the Rv1264 adenylyl cyclase, in which the N-terminal domain is autoinhibitory. Unsaturated fatty acids strongly stimulated Rv2212 activity by increasing substrate affinity. In addition, fatty acids greatly enhanced the pH sensitivity of the holoenzyme, thus converting Rv2212 to a pH sensor adenylyl cyclase. Fatty acid binding to Rv2212 was modelled by homology to a recent structure of the N-terminal domain of Rv1264, in which a fatty acid-binding pocket is defined. Rv2212 appears to integrate three cellular parameters: ATP concentration, presence of unsaturated fatty acids, and pH. These regulatory properties open the possibility that novel modes of cAMP-mediated signal transduction exist in the pathogen.
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Affiliation(s)
- Amira Abdel Motaal
- Abteilung Pharmazeutische Biochemie, Fakultät für Chemie und Pharmazie, Universität Tübingen, Germany
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27
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Loisel-Meyer S, Jiménez de Bagüés MP, Bassères E, Dornand J, Köhler S, Liautard JP, Jubier-Maurin V. Requirement of norD for Brucella suis virulence in a murine model of in vitro and in vivo infection. Infect Immun 2006; 74:1973-6. [PMID: 16495577 PMCID: PMC1418625 DOI: 10.1128/iai.74.3.1973-1976.2006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A mutant of Brucella suis bearing a Tn5 insertion in norD, the last gene of the operon norEFCBQD, encoding nitric oxide reductase, was unable to survive under anaerobic denitrifying conditions. The norD strain exhibited attenuated multiplication within nitric oxide-producing murine macrophages and rapid elimination in mice, hence demonstrating that norD is essential for Brucella virulence.
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Affiliation(s)
- Séverine Loisel-Meyer
- INSERM U431, Université Montpellier II, Place E. Bataillon, CC100, 34095 Montpellier Cedex 05, France
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28
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Bai G, McCue LA, McDonough KA. Characterization of Mycobacterium tuberculosis Rv3676 (CRPMt), a cyclic AMP receptor protein-like DNA binding protein. J Bacteriol 2005; 187:7795-804. [PMID: 16267303 PMCID: PMC1280308 DOI: 10.1128/jb.187.22.7795-7804.2005] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Accepted: 08/29/2005] [Indexed: 01/13/2023] Open
Abstract
Little is known about cyclic AMP (cAMP) function in Mycobacterium tuberculosis, despite its ability to encode 15 adenylate cyclases and 10 cNMP-binding proteins. M. tuberculosis Rv3676, which we have designated CRP(Mt), is predicted to be a cAMP-dependent transcription factor. In this study, we characterized CRP(Mt)'s interactions with DNA and cAMP, using experimental and computational approaches. We used Gibbs sampling to define a CRP(Mt) DNA motif that resembles the cAMP receptor protein (CRP) binding motif model for Escherichia coli. CRP(Mt) binding sites were identified in a total of 73 promoter regions regulating 114 genes in the M. tuberculosis genome, which are being explored as a regulon. Specific CRP(Mt) binding caused DNA bending, and the substitution of highly conserved nucleotides in the binding site resulted in a complete loss of binding to CRP(Mt). cAMP enhanced CRP(Mt)'s ability to bind DNA and caused allosteric alterations in CRP(Mt) conformation. These results provide the first direct evidence for cAMP binding to a transcription factor in M. tuberculosis, suggesting a role for cAMP signal transduction in M. tuberculosis and implicating CRP(Mt) as a cAMP-responsive global regulator.
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Affiliation(s)
- Guangchun Bai
- Wadsworth Center, New York State Department of Health, Albany, 12201-2002, USA
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29
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Guo YL, Kurz U, Schultz A, Linder JU, Dittrich D, Keller C, Ehlers S, Sander P, Schultz JE. Interaction of Rv1625c, a mycobacterial class IIIa adenylyl cyclase, with a mammalian congener. Mol Microbiol 2005; 57:667-77. [PMID: 16045612 DOI: 10.1111/j.1365-2958.2005.04675.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The adenylyl cyclase Rv1625c from Mycobacterium tuberculosis codes for a protein with six transmembrane spans and a catalytic domain, i.e. it corresponds to one half of the pseudoheterodimeric mammalian adenylyl cyclases (ACs). Rv1625c is active as a homodimer. We investigated the role of the Rv1625c membrane domain and demonstrate that it efficiently dimerizes the protein resulting in a 7.5-fold drop in K(m) for ATP. Next, we generated a duplicated Rv1625c AC dimer by a head-to-tail concatenation. This produced an AC with a domain order exactly as the mammalian pseudoheterodimers. It displayed positive cooperativity and a 60% increase of v(max) compared with the Rv1625c monomer. Further, we probed the compatibility of mycobacterial and mammalian membrane domains. The second membrane anchor in the Rv1625c concatamer was replaced with membrane domain I or II of rabbit type V AC. The mycobacterial and either mammalian membrane domains are compatible with each other and both recombinant proteins are active. A M. tuberculosis Rv1625c knockout strain was assayed in a mouse infection model. In vitro growth characteristics and in vivo organ infection and mortality were unaltered in the knockout strain indicating that AC Rv1625c alone is not a virulence factor.
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Affiliation(s)
- Ying Lan Guo
- Abt. Pharmazeutische Biochemie, Pharmazeutisches Institut, Universität Tübingen, Morgenstelle 8, D-72076 Tübingen, Germany
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30
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Gazdik MA, McDonough KA. Identification of cyclic AMP-regulated genes in Mycobacterium tuberculosis complex bacteria under low-oxygen conditions. J Bacteriol 2005; 187:2681-92. [PMID: 15805514 PMCID: PMC1070381 DOI: 10.1128/jb.187.8.2681-2692.2005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterium tuberculosis is the etiological agent of tuberculosis (TB), which kills approximately 2 million people a year despite current treatment options. A greater understanding of the biology of this bacterium is needed to better combat TB disease. The M. tuberculosis genome encodes as many as 15 adenylate cyclases, suggesting that cyclic AMP (cAMP) has an important, yet overlooked, role in mycobacteria. This study examined the effect of exogenous cAMP on protein expression in Mycobacterium bovis BCG grown under hypoxic versus ambient conditions. Both shaking and shallow standing cultures were examined for each atmospheric condition. Different cAMP-dependent changes in protein expression were observed in each condition by two-dimensional gel electrophoresis. Shaking low-oxygen cultures produced the most changes (12), while standing ambient conditions showed the fewest (2). Five upregulated proteins, Rv1265, Rv2971, GroEL2, PE_PGRS6a, and malate dehydrogenase, were identified from BCG by mass spectrometry and were shown to also be regulated by cAMP at the mRNA level in both M. tuberculosis H37Rv and BCG. To our knowledge, these data provide the first direct evidence for cAMP-mediated gene regulation in TB complex mycobacteria.
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Affiliation(s)
- Michaela A Gazdik
- New York State Department of Health, University of Albany, 120 New Scotland Ave., Albany, NY 12208, USA
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Zhao Q, He Z, Chen N, Cho YY, Zhu F, Lu C, Ma WY, Bode AM, Dong Z. 2-Arachidonoylglycerol stimulates activator protein-1-dependent transcriptional activity and enhances epidermal growth factor-induced cell transformation in JB6 P+ cells. J Biol Chem 2005; 280:26735-42. [PMID: 15886210 PMCID: PMC2227265 DOI: 10.1074/jbc.m412828200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
2-Arachidonoylglycerol (2-AG) is the most abundant endocannabinoid, and it plays a critical role in cannabinoid receptor-mediated cell signaling. Although 2-AG was shown to induce ERK activation via the cannabinoid receptor 1 (CB1), only a nonspecific CB receptor agonist and antagonist was used in those studies. Whether cannabinoid receptor 2 (CB2) is involved in 2-AG-induced ERK activation is still unclear. Moreover, whether 2-AG is involved in mediation of AP-1 activity and cell transformation is also not known. In the present study, we show that 2-AG stimulates AP-1-dependent transcriptional activity and enhances epidermal growth factor-induced cell transformation in mouse epidermal JB6 P+ Cl41 cells. Using JB6 P+ C141 cells, stably transfected with an AP-1 luciferase reporter, we found that 10 microm 2-AG induced up to a 3-fold stimulation of AP-1 transcriptional activity. The AP-1 stimulation appeared to be mediated by ERK but not JNK or p38 kinase. PD98059, a specific inhibitor of MEK1, almost completely blocked 2-AG-induced ERK phosphorylation and AP-1 activation. Using CB1/2-/- murine embryonic fibroblasts, we present the first direct evidence that both cannabinoid receptors 1 and 2 (CB1/2) are involved in 2-AG-induced ERK activation. 2-AG could not stimulate ERK phosphorylation or Fyn kinase activity in dominant negative Fyn. In addition, the Fyn inhibitor PP2 blocked 2-AG-induced Fyn kinase activity and ERK phosphorylation and activity. Small interfering RNA Fyn also suppressed 2-AG-induced ERK phosphorylation. Interestingly, 2-AG enhanced epidermal growth factor-induced AP-1 DNA binding and cell transformation. Taken together, our data provide direct evidence suggesting that 2-AG may have a novel role in cell transformation and carcinogenesis in a signaling pathway involving CB1/2 and activation of Fyn, ERKs, and AP-1.
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MESH Headings
- Animals
- Arachidonic Acids/pharmacology
- Cell Line
- Cell Transformation, Neoplastic/chemically induced
- Drug Synergism
- Endocannabinoids
- Epidermal Growth Factor/pharmacology
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Glycerides/pharmacology
- Mice
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-fyn
- Receptor, Cannabinoid, CB1/deficiency
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/deficiency
- Receptor, Cannabinoid, CB2/genetics
- Receptor, Cannabinoid, CB2/metabolism
- Signal Transduction
- Transcription Factor AP-1/drug effects
- Transfection
- src-Family Kinases/metabolism
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Affiliation(s)
| | | | | | | | | | | | | | | | - Zigang Dong
- Address correspondence to: Zigang Dong, Hormel Institute, University of Minnesota, 80116 Avenue NE, Austin, Minnesota 55912, Tel. 507-437-9600; Fax. 507-437-9606; E-Mail:
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Arellano-Reynoso B, Lapaque N, Salcedo S, Briones G, Ciocchini AE, Ugalde R, Moreno E, Moriyón I, Gorvel JP. Cyclic beta-1,2-glucan is a Brucella virulence factor required for intracellular survival. Nat Immunol 2005; 6:618-25. [PMID: 15880113 DOI: 10.1038/ni1202] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Accepted: 03/28/2005] [Indexed: 11/08/2022]
Abstract
Pathogenic brucella bacteria have developed strategies to persist for prolonged periods of time in host cells, avoiding innate immune responses. Here we show that the cyclic beta-1,2-glucans (CbetaG) synthesized by brucella is important for circumventing host cell defenses. CbetaG acted in lipid rafts found on host cell membranes. CbetaG-deficient mutants failed to prevent phagosome-lysosome fusion and could not replicate. However, when treated with purified CbetaG or synthetic methyl-beta-cyclodextrin, the mutants were able to control vacuole maturation by avoiding lysosome fusion, and this allowed intracellular brucella to survive and reach the endoplasmic reticulum. Fusion between the endoplasmic reticulum and the brucella-containing vacuole depended on the brucella virulence type IV secretion system but not on CbetaG. Brucella CbetaG is thus a virulence factor that interacts with lipid rafts and contributes to pathogen survival.
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Affiliation(s)
- Beatriz Arellano-Reynoso
- Centre d'Immunologie, Institut National de la Santé et de la Recherche Médicale-Centre National de la Recherche Scientifique de Marseille-Luminy, Case 906, 13288 Marseille CEDEX 9, France
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Jimenez de Bagues MP, Maria-Pilar JDB, Dudal S, Dornand J, Gross A. Cellular bioterrorism: how Brucella corrupts macrophage physiology to promote invasion and proliferation. Clin Immunol 2005; 114:227-38. [PMID: 15721833 DOI: 10.1016/j.clim.2004.07.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 07/22/2004] [Indexed: 01/18/2023]
Abstract
Brucellosis is a worldwide human zoonosis caused by intracellular bacteria of the genus Brucella. Virulence factors play an important role in allowing Brucella infection and proliferation within macrophages. Brucella enters macrophages through lipid raft microdomains, avoids phagolysosome fusion, and inhibits TNF-alpha secretion and apoptosis. Furthermore, Brucella can perturb bactericidal activity in macrophages by influencing the host cell response to its advantage through its LPS or by activating the cAMP/PKA pathway. To date, small steps have been taken in defining and understanding the virulence factors of Brucella used in macrophage subversion, but further investigation is required to fully explain virulence and persistence.
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Affiliation(s)
- Maria-Pilar Jimenez de Bagues
- Unidad de Sanidad Animal, Servicio de Investigación Agroalimentaria, Diputación General de Aragón, Ap. 727. 50080 Zaragoza, Spain
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Ha CT, Waterhouse R, Wessells J, Wu JA, Dveksler GS. Binding of pregnancy-specific glycoprotein 17 to CD9 on macrophages induces secretion of IL-10, IL-6, PGE2, and TGF-beta1. J Leukoc Biol 2005; 77:948-57. [PMID: 15772125 DOI: 10.1189/jlb.0804453] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Pregnancy-specific glycoproteins (PSGs) are a family of secreted proteins produced by the placenta, which are believed to have a critical role in pregnancy success. Treatment of monocytes with three members of the human PSGs induces interleukin (IL)-10, IL-6, and transforming growth factor-beta(1) (TGF-beta(1)) secretion. To determine whether human and murine PSGs have similar functions and use the same receptor, we treated wild-type and CD9-deficient macrophages with murine PSG17N and human PSG1 and -11. Our data show that murine PSG17N induced secretion of IL-10, IL-6, prostaglandin E(2), and TGF-beta(1) and that CD9 expression is required for the observed induction of cytokines. Therefore, the ability of PSG17 to induce anti-inflammatory cytokines parallels that of members of the human PSG family, albeit human and murine PSGs use different receptors, as CD9-deficient and wild-type macrophages responded equally to human PSGs. We then proceeded to examine the signaling mechanisms responsible for the CD9-mediated response to PSG17. Inhibition of cyclooxygenase 2 significantly reduced the PSG17N-mediated increase in IL-10 and IL-6. Further characterization of the response to PSG17 indicated that cyclic adenosine monophosphate-dependent protein kinase A (PKA) is involved in the up-regulation of IL-10 and IL-6, and it is not required for the induction of TGF-beta(1). Conversely, treatment of macrophages with a PKC inhibitor reduced the PSG17-mediated induction of TGF-beta(1), IL-6, and IL-10 significantly. The induction of anti-inflammatory cytokines by various PSGs supports the hypothesis that these glycoproteins have an essential role in the regulation of the maternal immune response in species with hemochorial placentation.
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Affiliation(s)
- Cam T Ha
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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Aronoff DM, Canetti C, Serezani CH, Luo M, Peters-Golden M. Cutting edge: macrophage inhibition by cyclic AMP (cAMP): differential roles of protein kinase A and exchange protein directly activated by cAMP-1. THE JOURNAL OF IMMUNOLOGY 2005; 174:595-9. [PMID: 15634874 DOI: 10.4049/jimmunol.174.2.595] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
cAMP has largely inhibitory effects on components of macrophage activation, yet downstream mechanisms involved in these effects remain incompletely defined. Elevation of cAMP in alveolar macrophages (AMs) suppresses FcgammaR-mediated phagocytosis. We now report that protein kinase A (PKA) inhibitors (H-89, KT-5720, and myristoylated PKA inhibitory peptide 14-22) failed to prevent this suppression in rat AMs. We identified the expression of the alternative cAMP target, exchange protein directly activated by cAMP-1 (Epac-1), in human and rat AMs. Using cAMP analogs that are highly specific for PKA (N6-benzoyladenosine-3',5'-cAMP) or Epac-1 (8-(4-chlorophenylthio)-2'-O-methyladenosine-3',5'-cAMP), we found that activation of Epac-1, but not PKA, dose-dependently suppressed phagocytosis. By contrast, activation of PKA, but not Epac-1, suppressed AM production of leukotriene B(4) and TNF-alpha, whereas stimulation of either PKA or Epac-1 inhibited AM bactericidal activity and H(2)O(2) production. These experiments now identify Epac-1 in primary macrophages, and define differential roles of Epac-1 vs PKA in the inhibitory effects of cAMP.
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Affiliation(s)
- David M Aronoff
- Division of Infectious Disease, Department of Internal Medicine, University of Michigan Health System, Ann Arbor 48109-0642, USA
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Abstract
The transactivation domain of the cAMP response element-binding protein (CREB) consists of two major domains. The glutamine-rich Q2 domain, which interacts with the general transcription factor TAFII130/135, is sufficient for the recruitment of a functional RNA polymerase II complex and allows basal transcriptional activity. The kinase-inducible domain, however, mediates signal-induced activation of CREB-mediated transcription. It is generally believed that recruitment of the coactivators CREB-binding protein (CBP) and p300 after signal-induced phosphorylation of this domain at serine-133 strongly enhances CREB-dependent transcription. Transcriptional activity of CREB can also be potentiated by phosphoserine-133-independent mechanisms, and not all stimuli that provoke phosphorylation of serine-133 stimulate CREB-dependent transcription. This review presents an overview of the diversity of stimuli that induce CREB phosphorylation at Ser-133, focuses on phosphoserine-133-dependent and -independent mechanisms that affect CREB-mediated transcription, and discusses different models that may explain the discrepancy between CREB Ser-133 phosphorylation and activation of CREB-mediated transcription.
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Affiliation(s)
- Mona Johannessen
- Department of Biochemistry, Institute of Medical Biology, University of Tromsø, N-9037, Norway
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Alves L, Mendonça Lima L, Silva Maeda E, Carvalho L, Holy J, Sarno EN, Pessolani MCV, Barker LP. Mycobacterium lepraeinfection of human Schwann cells depends on selective host kinases and pathogen-modulated endocytic pathways. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09786.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Yadav M, Roach SK, Schorey JS. Increased mitogen-activated protein kinase activity and TNF-alpha production associated with Mycobacterium smegmatis- but not Mycobacterium avium-infected macrophages requires prolonged stimulation of the calmodulin/calmodulin kinase and cyclic AMP/protein kinase A pathways. THE JOURNAL OF IMMUNOLOGY 2004; 172:5588-97. [PMID: 15100302 DOI: 10.4049/jimmunol.172.9.5588] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Previous studies have shown the mitogen-activated protein kinases (MAPKs) to be activated in macrophages upon infection with Mycobacterium, and that expression of TNF-alpha and inducible NO synthase by infected macrophages was dependent on MAPK activation. Additional analysis demonstrated a diminished activation of p38 and extracellular signal-regulated kinase (ERK)1/2 in macrophages infected with pathogenic strains of Mycobacterium avium compared with infections with the fast-growing, nonpathogenic Mycobacterium smegmatis and Mycobacterium phlei. However, the upstream signals required for MAPK activation and the mechanisms behind the differential activation of the MAPKs have not been defined. In this study, using bone marrow-derived macrophages from BALB/c mice, we determined that ERK1/2 activation was dependent on the calcium/calmodulin/calmodulin kinase II pathway in both M. smegmatis- and M. avium-infected macrophages. However, in macrophages infected with M. smegmatis but not M. avium, we observed a marked increase in cAMP production that remained elevated for 8 h postinfection. This M. smegmatis-induced cAMP production was also dependent on the calmodulin/calmodulin kinase pathway. Furthermore, stimulation of the cAMP/protein kinase A pathway in M. smegmatis-infected cells was required for the prolonged ERK1/2 activation and the increased TNF-alpha production observed in these infected macrophages. Our studies are the first to demonstrate an important role for the calmodulin/calmodulin kinase and cAMP/protein kinase A pathways in macrophage signaling upon mycobacterial infection and to show how cAMP production can facilitate macrophage activation and subsequent cytokine production.
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Affiliation(s)
- Mahesh Yadav
- Department of Biological Sciences, Center for Tropical Disease Research and Training, University of Notre Dame, Notre Dame, IN 46556, USA
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Castañeda-Roldán EI, Avelino-Flores F, Dall'Agnol M, Freer E, Cedillo L, Dornand J, Girón JA. Adherence of Brucella to human epithelial cells and macrophages is mediated by sialic acid residues. Cell Microbiol 2004; 6:435-45. [PMID: 15056214 DOI: 10.1111/j.1462-5822.2004.00372.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The basis for the interaction of Brucella species with the surface of epithelial cells before migration in the host within polymorphonuclear leucocytes is largely unknown. Here, we studied the ability of Brucella abortus and Brucella melitensis to adhere to cultured epithelial (HeLa and HEp-2) cells and THP-1-derived macrophages, and to bind extracellular matrix proteins (ECM). The brucellae adhered to epithelial cells forming localized bacterial microcolonies on the cell surface, and this process was inhibited significantly by pretreatment of epithelial cells with neuraminidase and sodium periodate and by preincubation of the bacteria with heparan sulphate and N-acetylneuraminic acid. Trypsinization of epithelial cells yielded increased adherence, suggesting unmasking of target sites on host cells. Notably, the brucellae also adhered to cultured THP-1 cells, and this event was greatly reduced upon removal of sialic acid residues from these cells with neuraminidase. B. abortus bound in a dose-dependent manner to immobilized fibronectin and vitronectin and, to a lesser extent, to chondroitin sulphate, collagen and laminin. In sum, our data strongly suggest that the adherence mechanism of brucellae to epithelial cells and macrophages is mediated by cellular receptors containing sialic acid and sulphated residues. The recognition of ECM (fibronectin and vitronectin) by the brucellae may represent a mechanism for spread within the host tissues. These are novel findings that offer new insights into understanding the interplay between Brucella and host cells.
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Affiliation(s)
- Elsa I Castañeda-Roldán
- Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edificio 76, Complejo de Ciencias, Puebla, México
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