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Open accessJournal ArticleDOI: 10.3389/FIMMU.2021.636644

Mycobacterium tuberculosis RipA Dampens TLR4-Mediated Host Protective Response Using a Multi-Pronged Approach Involving Autophagy, Apoptosis, Metabolic Repurposing, and Immune Modulation.

04 Mar 2021-Frontiers in Immunology (Frontiers Media SA)-Vol. 12, pp 636644-636644
Abstract: Reductive evolution has endowed Mycobacterium tuberculosis (M. tb) with moonlighting in protein functions. We demonstrate that RipA (Rv1477), a peptidoglycan hydrolase, activates the NFκB signaling pathway and elicits the production of pro-inflammatory cytokines, TNF-α, IL-6, and IL-12, through the activation of an innate immune-receptor, toll-like receptor (TLR)4. RipA also induces an enhanced expression of macrophage activation markers MHC-II, CD80, and CD86, suggestive of M1 polarization. RipA harbors LC3 (Microtubule-associated protein 1A/1B-light chain 3) motifs known to be involved in autophagy regulation and indeed alters the levels of autophagy markers LC3BII and P62/SQSTM1 (Sequestosome-1), along with an increase in the ratio of P62/Beclin1, a hallmark of autophagy inhibition. The use of pharmacological agents, rapamycin and bafilomycin A1, reveals that RipA activates PI3K-AKT-mTORC1 signaling cascade that ultimately culminates in the inhibition of autophagy initiating kinase ULK1 (Unc-51 like autophagy activating kinase). This inhibition of autophagy translates into efficient intracellular survival, within macrophages, of recombinant Mycobacterium smegmatis expressing M. tb RipA. RipA, which also localizes into mitochondria, inhibits the production of oxidative phosphorylation enzymes to promote a Warburg-like phenotype in macrophages that favors bacterial replication. Furthermore, RipA also inhibited caspase-dependent programed cell death in macrophages, thus hindering an efficient innate antibacterial response. Collectively, our results highlight the role of an endopeptidase to create a permissive replication niche in host cells by inducing the repression of autophagy and apoptosis, along with metabolic reprogramming, and pointing to the role of RipA in disease pathogenesis.

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Topics: Programmed cell death (56%), Autophagy (56%), Signal transduction (52%)

6 results found

Open accessJournal ArticleDOI: 10.3389/FIMMU.2021.696491
Neha Sharma1, Neha Sharma2, Mohd Shariq2, Neha Quadir1  +6 moreInstitutions (4)
Abstract: Mycobacterium tuberculosis (M. tb) is an intracellular pathogen that exploits moonlighting functions of its proteins to interfere with host cell functions. PE/PPE proteins utilize host inflammatory signaling and cell death pathways to promote pathogenesis. We report that M. tb PE6 protein (Rv0335c) is a secretory protein effector that interacts with innate immune toll-like receptor TLR4 on the macrophage cell surface and promotes activation of the canonical NFĸB signaling pathway to stimulate secretion of proinflammatory cytokines TNF-α, IL-12, and IL-6. Using mouse macrophage TLRs knockout cell lines, we demonstrate that PE6 induced secretion of proinflammatory cytokines dependent on TLR4 and adaptor Myd88. PE6 possesses nuclear and mitochondrial targeting sequences and displayed time-dependent differential localization into nucleus/nucleolus and mitochondria, and exhibited strong Nucleolin activation. PE6 strongly induces apoptosis via increased production of pro-apoptotic molecules Bax, Cytochrome C, and pcMyc. Mechanistic details revealed that PE6 activates Caspases 3 and 9 and induces endoplasmic reticulum-associated unfolded protein response pathways to induce apoptosis through increased production of ATF6, Chop, BIP, eIF2α, IRE1α, and Calnexin. Despite being a potent inducer of apoptosis, PE6 suppresses innate immune defense strategy autophagy by inducing inhibitory phosphorylation of autophagy initiating kinase ULK1. Inversely, PE6 induces activatory phosphorylation of autophagy master regulator MtorC1, which is reflected by lower conversion of autophagy markers LC3BI to LC3BII and increased accumulation of autophagy substrate p62 which is also dependent on innate immune receptor TLR4. The use of pharmacological agents, rapamycin and bafilomycin A1, confirms the inhibitory effect of PE6 on autophagy, evidenced by the reduced conversion of LC3BI to LC3BII and increased accumulation of p62 in the presence of rapamycin and bafilomycin A1. We also observed that PE6 binds DNA, which could have significant implications in virulence. Furthermore, our analyses reveal that PE6 efficiently binds iron to likely aid in intracellular survival. Recombinant Mycobacterium smegmatis (M. smegmatis) containing pe6 displayed robust growth in iron chelated media compared to vector alone transformed cells, which suggests a role of PE6 in iron acquisition. These findings unravel novel mechanisms exploited by PE6 protein to subdue host immunity, thereby providing insights relevant to a better understanding of host-pathogen interaction during M. tb infection.

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Topics: Programmed cell death (61%), Autophagy (58%), Signal transduction (57%) ... read more

Open accessJournal ArticleDOI: 10.3389/FIMMU.2021.706081
Manjunath P1, Javeed Ahmad2, Jasmine Samal, Javaid A. Sheikh1  +9 moreInstitutions (4)
Abstract: Dissecting the function(s) of proteins present exclusively in Mycobacterium tuberculosis (M.tb) will provide important clues regarding the role of these proteins in mycobacterial pathogenesis. Using extensive computational approaches, we shortlisted ORFs/proteins unique to M.tb among 13 different species of mycobacteria and identified a hypothetical protein Rv1509 as a 'signature protein' of M.tb. This unique protein was found to be present only in M.tb and absent in all other mycobacterial species, including BCG. In silico analysis identified numerous putative T cell and B cell epitopes in Rv1509. Initial in vitro experiments using innate immune cells demonstrated Rv1509 to be immunogenic with potential to modulate innate immune responses. Macrophages treated with Rv1509 exhibited higher activation status along with substantial release of pro-inflammatory cytokines. Besides, Rv1509 protein boosts dendritic cell maturation by increasing the expression of activation markers such as CD80, HLA-DR and decreasing DC-SIGN expression and this interaction was mediated by innate immune receptor TLR2. Further, in vivo experiments in mice demonstrated that Rv1509 protein promotes the expansion of multifunctional CD4+ and CD8+T cells and induces effector memory response along with evoking a canonical Th1 type of immune response. Rv1509 also induces substantial B cell response as revealed by increased IgG reactivity in sera of immunized animals. This allowed us to demonstrate the diagnostic efficacy of this protein in sera of human TB patients compared to the healthy controls. Taken together, our results reveal that Rv1509 signature protein has immunomodulatory functions evoking immunological memory response with possible implications in serodiagnosis and TB vaccine development.

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Topics: Acquired immune system (63%), Innate immune system (61%), Immune system (59%) ... read more

Open accessJournal ArticleDOI: 10.1080/21505594.2021.1990660
01 Nov 2021-Virulence
Abstract: The establishment of persistent infections and the reactivation of persistent bacteria to active bacilli are the two hurdles in effective tuberculosis treatment. Mycobacterium tuberculosis, an etio...

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Open accessJournal ArticleDOI: 10.3389/FCIMB.2021.766590
Kunli Zhang, Qiuyan Huang, Shou-Long Deng1, Yecheng Yang2  +2 moreInstitutions (2)
Abstract: Pathogenic infections have badly affected public health and the development of the breeding industry. Billions of dollars are spent every year fighting against these pathogens. The immune cells of a host produce reactive oxygen species and reactive nitrogen species which promote the clearance of these microbes. In addition, autophagy, which is considered an effective method to promote the destruction of pathogens, is involved in pathological processes. As research continues, the interplay between autophagy and nitroxidative stress has become apparent. Autophagy is always intertwined with nitroxidative stress. Autophagy regulates nitroxidative stress to maintain homeostasis within an appropriate range. Intracellular oxidation, in turn, is a strong inducer of autophagy. Toll-like receptor 4 (TLR4) is a pattern recognition receptor mainly involved in the regulation of inflammation during infectious diseases. Several studies have suggested that TLR4 is also a key regulator of autophagy and nitroxidative stress. In this review, we describe the role of TLR4 in autophagy and oxidation, and focus on its function in influencing autophagy-nitroxidative stress interactions.

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Topics: Autophagy (55%)

Open accessJournal ArticleDOI: 10.3390/BIOM11091278
26 Aug 2021-
Abstract: Curcumin is the principal curcuminoid obtained from the plant Curcuma longa and has been extensively studied for its biological and chemical properties. Curcumin displays a vast range of pharmacological properties, including antimicrobial, anti-inflammatory, antioxidant, and antitumor activity. Specifically, curcumin has been linked to the improvement of the outcome of tuberculosis. There are many reviews on the pharmacological effects of curcumin; however, reviews of the antitubercular activity are comparatively scarcer. In this review, we attempt to discuss the different aspects of the research on the antitubercular activity of curcumin. These include antimycobacterial activity, modulation of the host immune response, and enhancement of BCG vaccine efficacy. Recent advances in the antimycobacterial activity of curcumin synthetic derivatives, the role of computer aided drug design in identifying curcumin targets, the hepatoprotective role of curcumin, and the dosage and toxicology of curcumin will be discussed. While growing evidence supports the use of curcumin and its derivatives for tuberculosis therapy, further preclinical and clinical investigations are of pivotal importance before recommending the use of curcumin formulations in public health.

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Topics: Curcuminoid (57%), Curcumin (56%), Antimycobacterial (51%)


83 results found

Open accessJournal ArticleDOI: 10.1038/NMETH.2089
01 Jul 2012-Nature Methods
Abstract: For the past 25 years NIH Image and ImageJ software have been pioneers as open tools for the analysis of scientific images. We discuss the origins, challenges and solutions of these two programs, and how their history can serve to advise and inform other software projects.

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Topics: Image processing (54%), Bioimage informatics (52%)

34,063 Citations

Open accessJournal ArticleDOI: 10.1021/CT700301Q
Abstract: Molecular simulation is an extremely useful, but computationally very expensive tool for studies of chemical and biomolecular systems Here, we present a new implementation of our molecular simulation toolkit GROMACS which now both achieves extremely high performance on single processors from algorithmic optimizations and hand-coded routines and simultaneously scales very well on parallel machines The code encompasses a minimal-communication domain decomposition algorithm, full dynamic load balancing, a state-of-the-art parallel constraint solver, and efficient virtual site algorithms that allow removal of hydrogen atom degrees of freedom to enable integration time steps up to 5 fs for atomistic simulations also in parallel To improve the scaling properties of the common particle mesh Ewald electrostatics algorithms, we have in addition used a Multiple-Program, Multiple-Data approach, with separate node domains responsible for direct and reciprocal space interactions Not only does this combination of a

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Topics: Particle Mesh (50%)

12,609 Citations

Journal ArticleDOI: 10.1002/JCC.20291
David van der Spoel1, Erik Lindahl2, Berk Hess3, Gerrit Groenhof4  +2 moreInstitutions (4)
Abstract: This article describes the software suite GROMACS (Groningen MAchine for Chemical Simulation) that was developed at the University of Groningen, The Netherlands, in the early 1990s. The software, written in ANSI C, originates from a parallel hardware project, and is well suited for parallelization on processor clusters. By careful optimization of neighbor searching and of inner loop performance, GROMACS is a very fast program for molecular dynamics simulation. It does not have a force field of its own, but is compatible with GROMOS, OPLS, AMBER, and ENCAD force fields. In addition, it can handle polarizable shell models and flexible constraints. The program is versatile, as force routines can be added by the user, tabulated functions can be specified, and analyses can be easily customized. Nonequilibrium dynamics and free energy determinations are incorporated. Interfaces with popular quantum-chemical packages (MOPAC, GAMES-UK, GAUSSIAN) are provided to perform mixed MM/QM simulations. The package includes about 100 utility and analysis programs. GROMACS is in the public domain and distributed (with source code and documentation) under the GNU General Public License. It is maintained by a group of developers from the Universities of Groningen, Uppsala, and Stockholm, and the Max Planck Institute for Polymer Research in Mainz. Its Web site is

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Topics: Software suite (50%)

10,642 Citations

Open accessJournal ArticleDOI: 10.1093/BIOINFORMATICS/BTT055
Sander Pronk1, Szilárd Páll2, Szilárd Páll1, Roland Schulz3  +17 moreInstitutions (7)
01 Apr 2013-Bioinformatics
Abstract: Motivation: Molecular simulation has historically been a low-throughput technique, but faster computers and increasing amounts of genomic and structural data are changing this by enabling large-scale automated simulation of, for instance, many conformers or mutants of biomolecules with or without a range of ligands. At the same time, advances in performance and scaling now make it possible to model complex biomolecular interaction and function in a manner directly testable by experiment. These applications share a need for fast and efficient software that can be deployed on massive scale in clusters, web servers, distributed computing or cloud resources. Results: Here, we present a range of new simulation algorithms and features developed during the past 4 years, leading up to the GROMACS 4.5 software package. The software now automatically handles wide classes of biomolecules, such as proteins, nucleic acids and lipids, and comes with all commonly used force fields for these molecules built-in. GROMACS supports several implicit solvent models, as well as new free-energy algorithms, and the software now uses multithreading for efficient parallelization even on low-end systems, including windows-based workstations. Together with hand-tuned assembly kernels and state-of-the-art parallelization, this provides extremely high performance and cost efficiency for high-throughput as well as massively parallel simulations. Availability: GROMACS is an open source and free software available from Contact: Supplementary information:Supplementary data are available at Bioinformatics online.

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Topics: Software (52%), Massively parallel (51%)

5,130 Citations

Open accessJournal ArticleDOI: 10.1038/NPROT.2010.5
25 Mar 2010-Nature Protocols
Abstract: The iterative threading assembly refinement (I-TASSER) server is an integrated platform for automated protein structure and function prediction based on the sequence-to-structure-to-function paradigm. Starting from an amino acid sequence, I-TASSER first generates three-dimensional (3D) atomic models from multiple threading alignments and iterative structural assembly simulations. The function of the protein is then inferred by structurally matching the 3D models with other known proteins. The output from a typical server run contains full-length secondary and tertiary structure predictions, and functional annotations on ligand-binding sites, Enzyme Commission numbers and Gene Ontology terms. An estimate of accuracy of the predictions is provided based on the confidence score of the modeling. This protocol provides new insights and guidelines for designing of online server systems for the state-of-the-art protein structure and function predictions. The server is available at

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5,124 Citations