scholarly journals The Rab32/BLOC-3–dependent pathway mediates host defense against different pathogens in human macrophages

2021 ◽  
Vol 7 (3) ◽  
pp. eabb1795
Author(s):  
Massimiliano Baldassarre ◽  
Virtu Solano-Collado ◽  
Arda Balci ◽  
Rosa A. Colamarino ◽  
Ivy M. Dambuza ◽  
...  
Keyword(s):  
Host Defense ◽  
Oxidative Burst ◽  
Defense Mechanism ◽  
Mammalian Species ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Reduced Form ◽  
Nucleotide Exchange ◽  
Human Macrophages ◽  
Guanosine Triphosphatase ◽  
Lysosome Related Organelles

Macrophages provide a first line of defense against microorganisms, and while some mechanisms to kill pathogens such as the oxidative burst are well described, others are still undefined or unknown. Here, we report that the Rab32 guanosine triphosphatase and its guanine nucleotide exchange factor BLOC-3 (biogenesis of lysosome-related organelles complex–3) are central components of a trafficking pathway that controls both bacterial and fungal intracellular pathogens. This host-defense mechanism is active in both human and murine macrophages and is independent of well-known antimicrobial mechanisms such as the NADPH (reduced form of nicotinamide adenine dinucleotide phosphate)–dependent oxidative burst, production of nitric oxide, and antimicrobial peptides. To survive in human macrophages, Salmonella Typhi actively counteracts the Rab32/BLOC-3 pathway through its Salmonella pathogenicity island-1–encoded type III secretion system. These findings demonstrate that the Rab32/BLOC-3 pathway is a novel and universal host-defense pathway and protects mammalian species from various pathogens.

scholarly journals The Rab32/BLOC-3 dependent pathway mediates host- defence against different pathogens in human macrophages

2019 ◽  
Author(s):  
Massimiliano Baldassarre ◽  
Virtu Solano-Collado ◽  
Arda Balci ◽  
Rosa A. Colamarino ◽  
Ivy M Dambuza ◽  
...  
Keyword(s):  
Oxidative Burst ◽  
Mammalian Species ◽  
Host Defence ◽  
Intracellular Pathogens ◽  
Nucleotide Exchange ◽  
Human Macrophages ◽  
Guanine Nucleotide Exchange ◽  
Trafficking Pathway ◽  
Nucleotide Exchange Factor ◽  
Wide Range

ABSTRACTMacrophages provide a first line of defence against microorganisms, and while some mechanisms to kill pathogens such as the oxidative burst are well described, others are still undefined or unknown. Here we report that the Rab32 GTPase and its guanine nucleotide exchange factor BLOC-3 are central components of a trafficking pathway that controls both bacterial and fungal intracellular pathogens. This broad host-defence mechanism is active in both human and murine macrophages and is independent of well known antimicrobial mechanisms such as the NADPH-dependent oxidative burst, production of nitric oxide and antimicrobial peptides. To survive in human macrophages, Salmonella Typhi actively counteracts the Rab32/BLOC-3 pathway through its Salmonella pathogenicity island-1-encoded type III secretion system. These findings demonstrate that the Rab32/BLOC-3 pathway is a novel and universal host-defence pathway and protects mammalian species from a wide range of intracellular pathogens.

Current molecular models for NADPH oxidase regulation by Rac GTPase

Blood ◽  
2002 ◽  
Vol 100 (8) ◽  
pp. 2692-2695 ◽  
Author(s):  
Gary M. Bokoch ◽  
Becky A. Diebold
Keyword(s):  
Nadph Oxidase ◽  
Host Defense ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Oxygen Species ◽  
Molecular Models ◽  
Rac Gtpase ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
Guanosine Triphosphatase ◽  
Reduced Nicotinamide Adenine Dinucleotide

Reactive oxygen species (ROS) have been increasingly recognized as important components of cell signaling in addition to their well-established roles in host defense. The formation of ROS in phagocytic and nonphagocytic cells involves membrane-localized and Rac guanosine triphosphatase (GTPase)–regulated reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase(s). We discuss here the current molecular models for Rac GTPase action in the control of the phagocytic leukocyte NADPH oxidase. As a mechanistically detailed example of Rac GTPase signaling, the NADPH oxidase provides a potential paradigm for signaling by Rho family GTPases in general.

scholarly journals The Pentose Phosphate Pathway Dynamics in Cancer and Its Dependency on Intracellular pH

Metabolites ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 285 ◽  
Author(s):  
Khalid O. Alfarouk ◽  
Samrein B. M. Ahmed ◽  
Robert L. Elliott ◽  
Amanda Benoit ◽  
Saad S. Alqahtani ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Cancer Cells ◽  
Intracellular Ph ◽  
Pentose Phosphate Pathway ◽  
Cellular Proliferation ◽  
Defense Mechanism ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Pentose Phosphate ◽  
Reduced Form ◽  
The Warburg Effect

The Pentose Phosphate Pathway (PPP) is one of the key metabolic pathways occurring in living cells to produce energy and maintain cellular homeostasis. Cancer cells have higher cytoplasmic utilization of glucose (glycolysis), even in the presence of oxygen; this is known as the “Warburg Effect”. However, cytoplasmic glucose utilization can also occur in cancer through the PPP. This pathway contributes to cancer cells by operating in many different ways: (i) as a defense mechanism via the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) to prevent apoptosis, (ii) as a provision for the maintenance of energy by intermediate glycolysis, (iii) by increasing genomic material to the cellular pool of nucleic acid bases, (iv) by promoting survival through increasing glycolysis, and so increasing acid production, and (v) by inducing cellular proliferation by the synthesis of nucleic acid, fatty acid, and amino acid. Each step of the PPP can be upregulated in some types of cancer but not in others. An interesting aspect of this metabolic pathway is the shared regulation of the glycolytic and PPP pathways by intracellular pH (pHi). Indeed, as with glycolysis, the optimum activity of the enzymes driving the PPP occurs at an alkaline pHi, which is compatible with the cytoplasmic pH of cancer cells. Here, we outline each step of the PPP and discuss its possible correlation with cancer.

scholarly journals Trehalose alleviates high‐temperature stress in Pleurotus ostreatus by affecting central carbon metabolism

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Zhi-Yu Yan ◽  
Meng-Ran Zhao ◽  
Chen-Yang Huang ◽  
Li-Jiao Zhang ◽  
Jin-Xia Zhang
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
High Temperature ◽  
Temperature Stress ◽  
Pleurotus Ostreatus ◽  
Defense Mechanism ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
High Temperature Stress ◽  
Reduced Form ◽  
Protective Agent

Abstract Background Trehalose, an intracellular protective agent reported to mediate defense against many stresses, can alleviate high-temperature-induced damage in Pleurotus ostreatus. In this study, the mechanism by which trehalose relieves heat stress was explored by the addition of exogenous trehalose and the use of trehalose-6-phosphate synthase 1 (tps1) overexpression transformants. Results The results suggested that treatment with exogenous trehalose or overexpression of tps1 alleviated the accumulation of lactic acid under heat stress and downregulated the expression of the phosphofructokinase (pfk) and pyruvate kinase (pk) genes, suggesting an ameliorative effect of trehalose on the enhanced glycolysis in P. ostreatus under heat stress. However, the upregulation of hexokinase (hk) gene expression by trehalose indicated the involvement of the pentose phosphate pathway (PPP) in heat stress resistance. Moreover, treatment with exogenous trehalose or overexpression of tps1 increased the gene expression level and enzymatic activity of glucose-6-phosphate dehydrogenase (g6pdh) and increased the production of both the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione (GSH), confirming the effect of trehalose on alleviating oxidative damage by enhancing PPP in P. ostreatus under heat stress. Furthermore, treatment with exogenous trehalose or overexpression of tps1 ameliorated the decrease in the oxygen consumption rate (OCR) caused by heat stress, suggesting a relationship between trehalose and mitochondrial function under heat stress. Conclusions Trehalose alleviates high-temperature stress in P. ostreatus by inhibiting glycolysis and stimulating PPP activity. This study may provide further insights into the heat stress defense mechanism of trehalose in edible fungi from the perspective of intracellular metabolism.

scholarly journals Concentration of Sec12 at ER exit sites via interaction with cTAGE5 is required for collagen export

2014 ◽  
Vol 206 (6) ◽  
pp. 751-762 ◽  
Author(s):  
Kota Saito ◽  
Koh Yamashiro ◽  
Noriko Shimazu ◽  
Tomoya Tanabe ◽  
Kenji Kontani ◽  
...  
Keyword(s):  
Direct Interaction ◽  
Secretory Proteins ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Transport Vesicles ◽  
Nucleotide Exchange Factor ◽  
Receptor Component ◽  
Er Exit Sites ◽  
Guanosine Triphosphatase ◽  
Trimeric Structure

Mechanisms for exporting variably sized cargo from the endoplasmic reticulum (ER) using the same machinery remain poorly understood. COPII-coated vesicles, which transport secretory proteins from the ER to the Golgi apparatus, are typically 60–90 nm in diameter. However, collagen, which forms a trimeric structure that is too large to be accommodated by conventional transport vesicles, is also known to be secreted via a COPII-dependent process. In this paper, we show that Sec12, a guanine-nucleotide exchange factor for Sar1 guanosine triphosphatase, is concentrated at ER exit sites and that this concentration of Sec12 is specifically required for the secretion of collagen VII but not other proteins. Furthermore, Sec12 recruitment to ER exit sites is organized by its direct interaction with cTAGE5, a previously characterized collagen cargo receptor component, which functions together with TANGO1 at ER exit sites. These findings suggest that the export of large cargo requires high levels of guanosine triphosphate–bound Sar1 generated by Sec12 localized at ER exit sites.

scholarly journals Gamma Interferon Enhances Internalization and Early Nonoxidative Killing of Salmonella enterica Serovar Typhimurium by Human Macrophages and Modifies Cytokine Responses

2005 ◽  
Vol 73 (6) ◽  
pp. 3445-3452 ◽  
Author(s):  
Melita A. Gordon ◽  
Dominic L. Jack ◽  
David H. Dockrell ◽  
Margaret E. Lee ◽  
Robert C. Read
Keyword(s):  
Oxidative Burst ◽  
Respiratory Burst ◽  
Salmonella Enterica ◽  
Gamma Interferon ◽  
Cytokine Release ◽  
Intracellular Killing ◽  
Human Macrophages ◽  
Salmonella Infections ◽  
Serovar Typhimurium ◽  
Ifn Γ

ABSTRACT Gamma interferon (IFN-γ) is a critical cytokine in host defense against salmonella infections, but its role in phagocytic killing of intracellular Salmonella spp. has been investigated mainly in animal rather than human cells. We measured the effect of recombinant IFN-γ (rIFN-γ) priming on bacterial internalization, intracellular killing, oxidative burst, and cytokine release during phagocytosis of Salmonella enterica serovar Typhimurium by human monocyte-derived macrophages (MDM). Eleven-day-old MDM, primed for 72 h with rIFN-γ (100 ng/ml) exhibited an increased proportion of cells with associated bacteria (31% versus 26%, P = 0.036) and a 67% increase in internalized bacteria per cell compared to unprimed cells (P = 0.025). Retrieval of viable bacteria following internalization was reduced 3.6-fold in 72-h primed versus unprimed MDM (interquartile range, 3.1 to 6.4) at 0.5 h due to enhanced early intracellular killing, and this difference was maintained up to 24 h. In contrast, cells primed for only 24 h exhibited no increase in early killing. MDM were competent to produce an early oxidative burst when stimulated with phorbol myristate acetate, which was fully abrogated by the respiratory burst inhibitor diphenyleneiodonium chloride (DPI), but infection of MDM with S. enterica serovar Typhimurium did not cause an increase in the early respiratory burst under unprimed or primed conditions, and DPI had no effect on the early killing of bacteria by primed or unprimed MDM. During 24 h following infection, rIFN-γ-primed MDM released more interleukin-12 (IL-12) and less IL-10 relative to unprimed cells. We conclude that 72-h priming with rIFN-γ increases the efficiency of internalization and nonoxidative early intracellular killing of S. enterica serovar Typhimurium by human macrophages and modifies subsequent cytokine release.

scholarly journals Towards Initial Indications for a Thiol-Based Redox Control of Arabidopsis 5-Aminolevulinic Acid Dehydratase

Antioxidants ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 152 ◽  
Author(s):  
Daniel Wittmann ◽  
Sigri Kløve ◽  
Peng Wang ◽  
Bernhard Grimm
Keyword(s):  
Aminolevulinic Acid ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Thioredoxin Reductase ◽  
Reducing Power ◽  
Reduced Form ◽  
Redox Control ◽  
In Planta ◽  
Acid Dehydratase ◽  
Reducing Conditions ◽  
Alad Activity

Thiol-based redox control is one of the important posttranslational mechanisms of the tetrapyrrole biosynthesis pathway. Many enzymes of the pathway have been shown to interact with thioredoxin (TRX) and Nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase C (NTRC). We examined the redox-dependency of 5-aminolevulinic acid dehydratase (ALAD), which catalyzed the conjugation of two 5-aminolevulinic acid (ALA) molecules to porphobilinogen. ALAD interacted with TRX f, TRX m and NTRC in chloroplasts. Consequently, less ALAD protein accumulated in the trx f1, ntrc and trx f1/ntrc mutants compared to wild-type control resulting in decreased ALAD activity. In a polyacrylamide gel under non-reducing conditions, ALAD monomers turned out to be present in reduced and two oxidized forms. The reduced and oxidized forms of ALAD differed in their catalytic activity. The addition of TRX stimulated ALAD activity. From our results it was concluded that (i) deficiency of the reducing power mainly affected the in planta stability of ALAD; and (ii) the reduced form of ALAD displayed increased enzymatic activity.

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