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Cytosolic AND pH

Namrata Tomar, Shima Sadri, Allen W Cowley, Chun Yang, Nabeel Quryshi, Venkat R Pannala, Said H Audi, Ranjan K Dash
Reactive oxygen species (ROS) play an important role in cell signaling, growth, and immunity. However, when produced in excess, they are toxic to the cell and lead to premature aging and a myriad of pathologies, including cardiovascular and renal diseases. A major source of ROS in many cells is the family of NADPH oxidase (NOX), comprising of membrane and cytosolic components. NOX2 is among the most widely expressed and well-studied NOX isoform. Although details on the NOX2 structure, its assembly and activation, and ROS production are well elucidated experimentally, there is a lack of a quantitative and integrative understanding of the kinetics of NOX2 complex, and the various factors such as pH, inhibitory drugs, and temperature that regulate the activity of this oxidase...
February 12, 2019: Free Radical Biology & Medicine
Mark A Lobas, Rongkun Tao, Jun Nagai, Mira T Kronschläger, Philip M Borden, Jonathan S Marvin, Loren L Looger, Baljit S Khakh
Adenosine 5' triphosphate (ATP) is a universal intracellular energy source and an evolutionarily ancient, ubiquitous extracellular signal in diverse species. Here, we report the generation and characterization of single-wavelength genetically encoded fluorescent sensors (iATPSnFRs) for imaging extracellular and cytosolic ATP from insertion of circularly permuted superfolder GFP into the epsilon subunit of F0 F1 -ATPase from Bacillus PS3. On the cell surface and within the cytosol, iATPSnFR1.0 responds to relevant ATP concentrations (30 μM to 3 mM) with fast increases in fluorescence...
February 12, 2019: Nature Communications
Sang-Hyun Park, Ji Young Hyun, Injae Shin
Lysosomal pHs are maintained at low values by the cooperative action of a proton pump and a chloride channel to maintain electroneutrality. Owing to the biological significance of lysosomal chloride ions, measurements of their levels are of great importance to understand lysosome-associated biological events. However, appropriate probes to selectively detect Cl- ions within acidic lysosomes have not been developed to date. In this study, we prepared MQAE-MP, a lysosomal Cl- -selective fluorescent probe, and applied it to gain information about biological processes associated with lysosomes...
January 7, 2019: Chemical Science
Adele M Lehane, Adelaide S M Dennis, Katherine O Bray, Dongdi Li, Esther Rajendran, James M McCoy, Hillary M McArthur, Markus Winterberg, Farid Rahimi, Christopher J Tonkin, Kiaran Kirk, Giel G van Dooren
The Plasmodium falciparum ATPase Pf ATP4 is the target of a diverse range of antimalarial compounds, including the clinical drug candidate cipargamin.  Pf ATP4 was originally annotated as a Ca2+ transporter, but recent evidence suggests that it is a Na+ efflux pump, extruding Na+ in exchange for H+   Here we demonstrate that ATP4 proteins belong to a clade of P-type ATPases that are restricted to apicomplexans and their closest relatives.  We employed a variety of genetic and physiological approaches to investigate the ATP4 protein of the apicomplexan Toxoplasma gondii , Tg ATP4...
February 5, 2019: Journal of Biological Chemistry
Damini Singh, Amit Rahi, Romika Kumari, Vatika Gupta, Gunjan Gautam, Somya Aggarwal, Mohd Rehan, Rakesh Bhatnagar
The role of TatD DNases as DNA repair enzymes or cell death (apoptotic) nucleases is well established in prokaryotes as well as eukaryotes. The current study aims to characterize the TatD nuclease from Bacillus anthracis (Ba TatD) and to explore its key histidine catalytic residues. Ba TatD was found to be a metal-dependent, nonspecific endonuclease which could efficiently cleave double-stranded DNA substrates. Moreover, Ba TatD nuclease was observed to be thermostable up to 55°C and act in a wide pH range indicating its industrial applicability...
February 5, 2019: Journal of Cellular Biochemistry
Ryoma Teranishi, Takayuki Matsuda, Eiji Yuba, Kenji Kono, Atsushi Harada
Sonodynamic therapy (SDT) is a novel promising noninvasive therapy involving utilization of low-intensity ultrasound and sonosensitizer, which can generate reactive oxygen species (ROS) by sonication. In SDT, a high therapeutic effect is achieved by intracellular delivery and accumulation at the target sites of sonosensitizer followed by oxidative damage of produced ROS by sonication. Here, pH- and redox-responsive hollow nanocapsules are prepared through the introduction of disulfide cross-linkages to self-assembled polymer vesicles formed from polyamidoamine dendron-poly(l-lysine) for the efficient delivery of sonosensitizer...
February 1, 2019: Macromolecular Bioscience
Elsayed Metwally, Guoli Zhao, Wenhua Li, Qifu Wang, Yong Q Zhang
Calpains are calcium dependent, cytosolic proteinases active at neutral pH. They do not degrade but cleave substrates at limited sites. Calpains are implicated in various pathologies such as ischemia, injuries, muscular dystrophy, and neurodegeneration. Despite so, the physiological function of calpains remains to be clearly defined. Using the neuromuscular junction of Drosophila of both sexes as a model, we performed RNAi screening and uncovered that calpains negatively regulated protein levels of the glutamate receptor GluRIIA but not GluRIIB...
January 31, 2019: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Chen-Guang Liu, Ranjith Kumar Kankala, Hong-Yue Liao, Ai-Zheng Chen, Shi-Bin Wang
Spurred by the current advancements in engineering various intelligent nanoparticle-based drug delivery systems, conjugation of drugs with the stimuli-responsive molecular switches has become one of the most efficient approaches to deliver a drug cargo in spatiotemporal controlled fashions. In this study, we fabricated an innovative pH-triggered Hydrazone-carboxylate complex of doxorubicin (Dox), which was subsequently encapsulated in the layered double hydroxide (LDH) nanoparticles for effective cancer therapeutics...
January 16, 2019: Journal of Biomedical Materials Research. Part A
Kameron V Kilchrist, Somtochukwu C Dimobi, Meredith A Jackson, Brian C Evans, Thomas A Werfel, Eric A Dailing, Sean K Bedingfield, Isom B Kelly, Craig L Duvall
Endo-lysosome entrapment is one of the key barriers to therapeutic use of biologic drugs that act intracellularly. Screening of prospective nanoscale endosome-disrupting delivery technologies is currently limited by methods that are indirect and cumbersome. Here we statistically validate Galectin 8 (Gal8) intracellular tracking as a superior approach that is direct, quantitative, and predictive of therapeutic cargo intracellular bioactivity in vitro high throughput screening and in vivo validation. Gal8 is a cytosolically-dispersed protein that, when endosomes are disrupted, redistributes by binding to glycosylation moieties selectively located on the inner face of endosomal membranes...
January 10, 2019: ACS Nano
Abhijit Biswas, Kasturee Chakraborty, Chiranjit Dutta, Sanchita Mukherjee, Paramita Gayen, Somnath Jan, Argha Mario Mallick, Dhananjay Bhattacharyya, Rituparna Sinha Roy
Cytosolic delivery of functional siRNA remains the major challenge to develop siRNA based therapeutics. Designing clinically safe and effective siRNA transporter to deliver functional siRNA across the plasma and endosomal membrane remains a key hurdle. With the aim of improving endosomal release, we have designed cyclic and linear peptide based transporters having Arg-DHis-Arg template. Computational studies show that Arg-DHis-Arg template is also stabilized by Arg-His side-chain hydrogen bonding interaction at physiological pH, which dissociates at lower pH...
January 10, 2019: ACS Applied Materials & Interfaces
Peace Atakpa, Laura M van Marrewijk, Michael Apta-Smith, Sumita Chakraborty, Colin W Taylor
GPN (glycyl-l-phenylalanine 2-naphthylamide) is widely used to perturb lysosomes because its cleavage by the lysosomal enzyme, cathepsin C, is proposed to rupture lysosomal membranes. We show that GPN evokes a sustained increase in lysosomal pH (pHly ), and transient increases in cytosolic pH (pHcyt ) and Ca2+ concentration ([Ca2+ ]c ). None of these effects require cathepsin C, nor are they accompanied by rupture of lysosomes, but they are mimicked by structurally unrelated weak bases. GPN-evoked increases in [Ca2+ ]c require Ca2+ within the ER, but they are not mediated by ER Ca2+ channels amplifying Ca2+ release from lysosomes...
January 7, 2019: Journal of Cell Science
Amy E Ford, Catherine Denicourt, Kevin A Morano
The eukaryotic cytosolic proteome is vulnerable to changes in proteostatic and redox balance caused by temperature, pH, oxidants and xenobiotics. Cysteine-containing proteins are especially at risk as the thiol side chain is subject to oxidation, adduction and chelation by thiol-reactive compounds. The thiol-chelating heavy metal cadmium is a highly toxic environmental pollutant demonstrated to induce the heat shock response and recruit protein chaperones to sites of presumed protein aggregation in the budding yeast Saccharomyces cerevisiae...
January 2, 2019: Molecular Biology of the Cell
Yage Zhang, Fakun Cao, Yuhuan Zhou, Zhen Feng, Brian Sit, Mira Krendel, Cheng-Han Yu
During the podosome formation, distinct phosphatidylinositol 3,4,5-trisphosphate lipid (PI(3,4,5)P3) production and F-actin polymerization take place at integrin-mediated adhesions. Membrane-associated actin regulation factors, such as myosin-1, serve as key molecules to link phosphatidylinositol signals to podosome assembly. Here, we report that long-tailed myosin-1e (Myo1e) is enriched at the ventral layer of the podosome core in a PI(3,4,5)P3 dependent manner. Combination of TH1 and TH2 (TH12) of Myo1e tail domains contains the essential motif for PI(3,4,5)P3-dependent membrane association and ventral localization at the podosome...
January 2, 2019: Molecular Biology of the Cell
Yong-Qiang Gao, Wei-Hua Wu, Yi Wang
Stomatal movement, which plays an essential role in plant transpiration and photosynthesis, is controlled by ion channels that mediate K+ and anion fluxes across the plasma membrane (PM) of guard cells. These channels in dicots are accurately regulated by various physiological factors, such as pH, ABA, and Ca2+; however, the data in monocots are limited. Here the whole-cell patch-clamping technique was applied to analyze the properties and regulations of PM K+ channels in maize guard cells. The results indicated that the hyperpolarization-activated inward-rectifying channels were highly K+-selective...
December 24, 2018: Plant & Cell Physiology
Shengyun Huang, Getu Kahsay, Erwin Adams, Ann Van Schepdael
An optimized and economical capillary electrophoretic method for both off-line and on-line study of the enzyme aldehyde oxidase and its substrate phthalazine was developed. The separation of the substrate phthalazine and its metabolite 1-phthalazinone was achieved using micellar electrokinetic chromatography (MEKC) with sodium dodecyl sulphate in the background electrolyte (BGE). The BGE consists of 25 mM sodium phosphate buffer containing 50 mM sodium dodecyl sulphate at pH 7.4. A bare-fused-silica capillary with a capillary length of 40 cm, 50 μm ID and effective length of 30 cm was used to develop the capillary electrophoresis method...
December 19, 2018: Journal of Pharmaceutical and Biomedical Analysis
Suiping Zhou, Chandra Dodia, Sheldon I Feinstein, Sandra Harper, Henry J Forman, David W Speicher, Aron B Fisher
The expression of the phospholipase A₂ activity (aiPLA₂) of peroxiredoxin 6 (Prdx6) in the cell cytoplasm is physiologically relevant for the repair of peroxidized cell membranes, but aiPLA₂ assay in vitro indicates that, unlike assay at pH 4, activity at cytosolic pH is essentially absent with non-oxidized substrate. However, the addition of glutathione (GSH) to the assay medium significantly increased aiPLA₂ activity at cytosolic pH, while oxidized GSH (GSSG) and several other thiols had no effect...
December 24, 2018: Antioxidants (Basel, Switzerland)
George M Kennedy, Michael Y Min, Jacob F Fitzgerald, Michael T Nguyen, Samantha L Schultz, Madison T Crum, Jeffrey A Starke, Michael A Butkus, Dwight D Bowman, Michael P Labare
AIMS: This study was performed to evaluate the efficacy of butanoic acid against bacterial pathogens including Acinetobacter baumannii and Staphylococcus pseudintermedius. METHODS AND RESULTS: Vegetative bacteria were exposed to butanoic acid in vitro and log reduction was quantified using viable count assays. Maximum (8 and 9) log inactivation was determined by qualitatively assaying for growth/no-growth after a 48 h incubation (37°C). Membrane integrity after exposure to butanoic acid was determined by propidium iodide staining, SEM, membrane depolarization, and ICP analysis...
December 22, 2018: Journal of Applied Microbiology
Daniele Sanna, Jessica Palomba, Giuseppe Lubinu, Péter Buglyó, Sándor Nagy, Franc Perdih, Eugenio Garribba
The interaction with erythrocytes of four [VV O2 L2 ]- complexes, with L = picolinate (pic), 5-cyanopicolinate (picCN), 3-aminopyrazine-2-carboxylate (przNH2 ), and 1,2-dimethyl-3-hydroxy-4(1 H)-pyridinonate (dhp), was studied. The thermodynamic stability at physiological pH is: [VV O2 (dhp)2 ]- > [VV O2 (przNH2 )2 ]- > [VV O2 (pic)2 ]- > [VV O2 (picCN)2 ]- . With picCN and pic, V exists at physiological pH as H2 VV O4 - , with przNH2 as a mixture of H2 VV O4 - and [VV O2 (przNH2 )2 ]- and with dhp as [VV O2 (dhp)2 ]- ...
December 21, 2018: Journal of Medicinal Chemistry
Yun-Long Zhang, Rui Zhang, Yi-Fan Shen, Kai-Yue Huang, Yang-Yang He, Jun-Han Zhao, Zhi-Cheng Jing
Background: The shift of metabolism from mitochondrial oxidative phosphorylation to glycolysis and mitochondria binding partner of hexokinase are features common to cancer. These have been seen in pulmonary hypertension (PH) as well. An inhibitor of hexokinase 2 (HK 2), the small molecule 3-bromopyruvate (3-BrPA) is incredibly powerful and swift acting anticancer agent. However, whether it could be of potential benefit to PH was still unknown. METHODS: Sprague-Dawley rats with monocrotaline (MCT)-induced PH were administered two different oral doses of 3-BrPA (15mg/kg/d and 30mg/kg/d, respectively) for 14 days...
December 18, 2018: American Journal of Hypertension
Kwok-Ho Lam, Zhuojun Guo, Nadja Krez, Tsutomu Matsui, Kay Perry, Jasmin Weisemann, Andreas Rummel, Mark E Bowen, Rongsheng Jin
Botulinum neurotoxin (BoNT) delivers its protease domain across the vesicle membrane to enter the neuronal cytosol upon vesicle acidification. This process is mediated by its translocation domain (HN ), but the molecular mechanism underlying membrane insertion of HN remains poorly understood. Here, we report two crystal structures of BoNT/A1 HN that reveal a novel molecular switch (termed BoNT-switch) in HN , where buried α-helices transform into surface-exposed hydrophobic β-hairpins triggered by acidic pH...
December 18, 2018: Nature Communications
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