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Li Z, Li S, Du L, Zhang X, Jiang Y, Liu W, Zhang W, Li S. Engineering Bafilomycin High-Producers by Manipulating Regulatory and Biosynthetic Genes in the Marine Bacterium Streptomyces lohii. Mar Drugs 2021; 19:md19010029. [PMID: 33440628 PMCID: PMC7827423 DOI: 10.3390/md19010029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/25/2020] [Accepted: 01/08/2021] [Indexed: 11/16/2022] Open
Abstract
Bafilomycin A1 is the representative compound of the plecomacrolide natural product family. This 16-membered ring plecomacrolide has potent antifungal and vacuolar H+-ATPase inhibitory activities. In our previous work, we identified a bafilomycin biosynthetic gene cluster (baf) from the marine bacterium Streptomyces lohii ATCC BAA-1276, wherein a luxR family regulatory gene orf1 and an afsR family regulatory gene bafG were revealed based on bioinformatics analysis. In this study, the positive regulatory roles of orf1 and bafG for bafilomycin biosynthesis are characterized through gene inactivation and overexpression. Compared to the wild-type S. lohii strain, the knockout of either orf1 or bafG completely abolished the production of bafilomycins. The overexpression of orf1 or bafG led to 1.3- and 0.5-fold increased production of bafilomycins, respectively. A genetically engineered S. lohii strain (SLO-08) with orf1 overexpression and inactivation of the biosynthetic genes orf2 and orf3, solely produced bafilomycin A1 with the titer of 535.1 ± 25.0 mg/L in an optimized fermentation medium in shaking flasks. This recombinant strain holds considerable application potential in large-scale production of bafilomycin A1 for new drug development.
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Affiliation(s)
- Zhong Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
- Shandong Provincial Key Laboratory of Synthetic Biology, CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuai Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
| | - Lei Du
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
| | - Xingwang Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
| | - Yuanyuan Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
- Shandong Provincial Key Laboratory of Synthetic Biology, CAS Key Laboratory of Biofuels at Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenhua Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
| | - Wei Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
| | - Shengying Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China; (Z.L.); (S.L.); (L.D.); (X.Z.); (Y.J.); (W.L.); (W.Z.)
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
- Correspondence:
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2
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Yuan Y, He X, Wang T, Zhang X, Li Z, Xu X, Zhang W, Yan X, Li S, He S. Efficient Preparation of Bafilomycin A1 from Marine Streptomyces lohii Fermentation Using Three-Phase Extraction and High-Speed Counter-Current Chromatography. Mar Drugs 2020; 18:E332. [PMID: 32630403 DOI: 10.3390/md18060332] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/20/2020] [Accepted: 06/23/2020] [Indexed: 11/23/2022] Open
Abstract
An efficient strategy was developed for the rapid separation and enrichment of bafilomycin A1 (baf A1) from a crude extract of the marine microorganism Streptomyces lohii fermentation. This strategy comprises liquid−liquid extraction (LLE) with a three-phase solvent system (n-hexane–ethyl acetate–acetonitrile–water = 7:3:5:5, v/v/v/v) followed by separation using high-speed counter-current chromatography (HSCCC). The results showed that a 480.2-mg fraction of baf A1-enriched extract in the middle phase of the three-phase solvent system was prepared from 4.9 g of crude extract after two consecutive one-step operations. Over 99% of soybean oil, the main hydrophobic waste in the crude extract, and the majority of hydrophilic impurities were distributed in the upper and lower phase, respectively. HSCCC was used with a two-phase solvent system composed of n-hexane–acetonitrile–water (15:8:12, v/v/v) to isolate and purify baf A1 from the middle phase fraction, which yielded 77.4 mg of baf A1 with > 95% purity within 90 min. The overall recovery of baf A1 in the process was determined to be 95.7%. The use of a three-phase solvent system represents a novel strategy for the simultaneous removal of hydrophobic oil and hydrophilic impurities from a microbial fermentation extract.
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Scheffler K, Bilz NC, Brueckner M, Stanifer ML, Boulant S, Claus C, Reibetanz U. Enhanced Uptake and Endosomal Release of LbL Microcarriers Functionalized with Reversible Fusion Proteins. ACS Appl Bio Mater 2020; 3:1553-1567. [PMID: 35021646 DOI: 10.1021/acsabm.9b01168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The efficient application of smart drug-delivery systems requires further improvement of their cellular uptake and in particular their release from endolysosomal compartments into the cytoplasm of target cells. The usage of virus proteins allows for such developments, as viruses have evolved efficient entry mechanisms into the cell, mediated by their fusion proteins. In our investigations, the transferability of the glycoprotein G which is a fusion protein of the vesicular stomatitis virus (VSV-G) onto the surface of a layer-by-layer (LbL) designed microcarrier was investigated. The assembly of VSV-G as a reversible viral fusion protein onto LbL microcarriers indeed induced an enhanced uptake rate on Vero cells as well as a fast and efficient release of the intact carriers from endolysosomes into the cytoplasm. Additionally, neither virus-associated effects on cellular viability nor activation of an interferon response were detected. Our study emphasizes the suitability of VSV-G as an efficient surface functionalization of drug-delivery systems.
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Affiliation(s)
- Kira Scheffler
- Institute for Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, D-04107 Leipzig, Germany
| | - Nicole C Bilz
- Institute of Virology, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Mandy Brueckner
- Institute for Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, D-04107 Leipzig, Germany
| | - Megan L Stanifer
- Schaller Research Group at CellNetworks, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Steeve Boulant
- Schaller Research Group at CellNetworks, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany.,Research Group "Cellular Polarity and Viral Infection" (F140), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Claudia Claus
- Institute of Virology, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Uta Reibetanz
- Institute for Medical Physics and Biophysics, Faculty of Medicine, University of Leipzig, D-04107 Leipzig, Germany
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Hu CMJ, Chen YT, Fang ZS, Chang WS, Chen HW. Antiviral efficacy of nanoparticulate vacuolar ATPase inhibitors against influenza virus infection. Int J Nanomedicine 2018; 13:8579-8593. [PMID: 30587980 PMCID: PMC6298390 DOI: 10.2147/ijn.s185806] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background Influenza virus infections are a major public health concern worldwide. Conventional treatments against the disease are designed to target viral proteins. However, the emergence of viral variants carrying drug-resistant mutations can outpace the development of pathogen-targeting antivirals. Diphyllin and bafilomycin are potent vacuolar ATPase (V-ATPase) inhibitors previously shown to have broad-spectrum antiviral activity. However, their poor water solubility and potential off-target effect limit their clinical application. Methods In this study, we report that nanoparticle encapsulation of diphyllin and bafilomycin improves the drugs’ anti-influenza applicability. Results Using PEG-PLGA diblock copolymers, sub-200 nm diphyllin and bafilomycin nanoparticles were prepared, with encapsulation efficiency of 42% and 100%, respectively. The drug-loaded nanoparticles have sustained drug release kinetics beyond 72 hours and facilitate intracellular drug delivery to two different influenza virus-permissive cell lines. As compared to free drugs, the nanoparticulate V-ATPase inhibitors exhibited lower cytotoxicity and greater in vitro antiviral activity, improving the therapeutic index of diphyllin and bafilomycin by approximately 3 and 5-fold, respectively. In a mouse model of sublethal influenza challenge, treatment with diphyllin nanoparticles resulted in reduced body weight loss and viral titer in the lungs. In addition, following a lethal influenza viral challenge, diphyllin nanoparticle treatment conferred a survival advantage of 33%. Conclusions These results demonstrate the potential of the nanoparticulate V-ATPase inhibitors for host-targeted treatment against influenza.
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Affiliation(s)
- Che-Ming Jack Hu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Research Center for Nanotechnology and Infectious Diseases, Taipei, Taiwan,
| | - You-Ting Chen
- Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan,
| | - Zih-Syun Fang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan,
| | - Wei-Shan Chang
- Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan,
| | - Hui-Wen Chen
- Research Center for Nanotechnology and Infectious Diseases, Taipei, Taiwan, .,Department of Veterinary Medicine, National Taiwan University, Taipei, Taiwan,
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5
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Schaffner-Barbero C, Miskinyte M, Grewal JS, Schnaufer A. Pharmacological Inhibition of the Vacuolar ATPase in Bloodstream-Form Trypanosoma brucei Rescues Genetic Knockdown of Mitochondrial Gene Expression. Antimicrob Agents Chemother 2018; 62:e02268-17. [PMID: 29914945 DOI: 10.1128/AAC.02268-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 06/08/2018] [Indexed: 11/20/2022] Open
Abstract
Trypanosomatid parasites cause diseases in humans and livestock. It was reported that partial inhibition of the vacuolar ATPase (V-ATPase) affects the dependence of Trypanosoma brucei on its mitochondrial genome (kinetoplast DNA [kDNA]), a target of the antitrypanosomatid drug isometamidium. Here, we report that V-ATPase inhibition with bafilomycin A1 (BafA) provides partial resistance to genetic knockdown of mitochondrial gene expression. BafA does not promote long-term survival after kDNA loss, but in its presence, isometamidium causes less damage to kDNA.
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6
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Parousis A, Carter HN, Tran C, Erlich AT, Mesbah Moosavi ZS, Pauly M, Hood DA. Contractile activity attenuates autophagy suppression and reverses mitochondrial defects in skeletal muscle cells. Autophagy 2018; 14:1886-1897. [PMID: 30078345 PMCID: PMC6152519 DOI: 10.1080/15548627.2018.1491488] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 06/05/2018] [Accepted: 06/18/2018] [Indexed: 12/18/2022] Open
Abstract
Macroautophagy/autophagy is a survival mechanism that facilitates protein turnover in post-mitotic cells in a lysosomal-dependent process. Mitophagy is a selective form of autophagy, which arbitrates the selective recognition and targeting of aberrant mitochondria for degradation. Mitochondrial content in cells is the net balance of mitochondrial catabolism via mitophagy, and organelle biogenesis. Although the latter process has been well described, mitophagy in skeletal muscle is less understood, and it is currently unknown how these two opposing mechanisms converge during contractile activity. Here we show that chronic contractile activity (CCA) in muscle cells induced mitochondrial biogenesis and coordinately enhanced the expression of TFEB (transcription factor EB) and PPARGC1A/PGC-1α, master regulators of lysosome and mitochondrial biogenesis, respectively. CCA also enhanced the expression of PINK1 and the lysosomal protease CTSD (cathepsin D). Autophagy blockade with bafilomycin A1 (BafA) reduced mitochondrial state 3 and 4 respiration, increased ROS production and enhanced the accumulation of MAP1LC3B-II/LC3-II and SQSTM1/p62. CCA ameliorated this mitochondrial dysfunction during defective autophagy, increased PPARGC1A, normalized LC3-II levels and reversed mitochondrially-localized SQSTM1 toward control levels. NAC emulated the LC3-II reductions induced by contractile activity, signifying that a decrease in oxidative stress could represent a mechanism of autophagy normalization brought about by CCA. CCA enhances mitochondrial biogenesis and lysosomal activity, and normalizes autophagy flux during autophagy suppression, partly via ROS-dependent mechanisms. Thus, contractile activity represents a potential therapeutic intervention for diseases in which autophagy is inhibited, such as vacuolar myopathies in skeletal muscle, by establishing a healthy equilibrium of anabolic and catabolic pathways. ABBREVIATIONS AMPK: AMP-activated protein kinase; BafA: bafilomycin A1; BNIP3L: BCL2/adenovirus E1B interacting protein 3-like; CCA: chronic contractile activity; COX4I1: cytochrome c oxidase subunit 4I1; DMEM: Dulbecco's modified Eagle's medium; GFP: green fluorescent protein; LSD: lysosomal storage diseases; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MTORC1: mechanistic target of rapamycin kinase complex 1; NAC: N-acetylcysteine; PPARGC1A: peroxisome proliferative activated receptor, gamma, coactivator 1 alpha; PINK1: PTEN induced putative kinase 1; ROS: reactive oxygen species; SOD2: superoxide dismutase 2, mitochondrial; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB.
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Affiliation(s)
- Alexa Parousis
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Heather N. Carter
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Claudia Tran
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Avigail T. Erlich
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Zahra S. Mesbah Moosavi
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Marion Pauly
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - David A. Hood
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
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7
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Luhr M, Szalai P, Engedal N. The Lactate Dehydrogenase Sequestration Assay - A Simple and Reliable Method to Determine Bulk Autophagic Sequestration Activity in Mammalian Cells. J Vis Exp 2018:57971. [PMID: 30102280 PMCID: PMC6126555 DOI: 10.3791/57971] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Bulk autophagy is characterized by the sequestration of large portions of cytoplasm into double/multi-membrane structures termed autophagosomes. Here a simple protocol to monitor this process is described. Moreover, typical results and experimental validation of the method under autophagy-inducing conditions in various types of cultured mammalian cells are provided. During bulk autophagy, autophagosomes sequester cytosol, and thereby also soluble cytosolic proteins, alongside other autophagic cargo. LDH is a stable and highly abundant, soluble cytosolic enzyme that is non-selectively sequestered into autophagosomes. The amount of LDH sequestration therefore reflects the amount of bulk autophagic sequestration. To efficiently and accurately determine LDH sequestration in cells, we employ an electrodisruption-based fractionation protocol that effectively separates sedimentable from cytosolic LDH, followed by measurement of enzymatic activity in sedimentable fractions versus whole-cell samples. Autophagic sequestration is determined by subtracting the proportion of sedimentable LDH in untreated cells from that in treated cells. The advantage of the LDH sequestration assay is that it gives a quantitative measure of the autophagic sequestration of endogenous cargo, as opposed to other methods that either involve ectopic expression of sequestration probes or semi-quantitative protease protection analyses of autophagy markers or receptors.
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Affiliation(s)
- Morten Luhr
- The Autophagy Team, Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo
| | - Paula Szalai
- The Autophagy Team, Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo
| | - Nikolai Engedal
- The Autophagy Team, Centre for Molecular Medicine Norway (NCMM), Nordic EMBL Partnership, University of Oslo;
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Abstract
Vacuolar H+-ATPases (V-ATPases) are multi-subunit enzymes that play housekeeping roles in eukaryotic cells by acidifying lysosomes, late endosomes, Golgi, and other membrane-bounded compartments. Beyond that, V-ATPases have specialized functions in certain cell types linked to diseases including osteoporosis and cancer. Efforts to identify strategies to develop inhibitors selective for V-ATPases that are involved in disease progression have been ongoing for more than two decades, but so far have not yielded a therapeutic agent that has been translated to the clinic. Recent basic science studies have identified unexpected roles for V-ATPases in nutrient and energy sensing, and renin/angiotensin signaling, which offer additional incentives for considering V-ATPases as therapeutic targets. This article briefly reviews efforts to utilize inhibitors of V-ATPases as drugs. Primary focus is on recent "rational" efforts to identify small molecule inhibitors of the V-ATPases that are selectively expressed in osteoclasts and cancer cells. Enoxacin and bis-enoxacin are two molecules that emerged from these efforts. These molecules block a binding interaction between V-ATPases and microfilaments that occurs in osteoclasts, but not most other cell types, which relates to the specialized function of V-ATPases in bone resorption. Enoxacin and bis-enoxacin have proven useful in the treatment of bone diseases and cancer in animal models and display therapeutic effects that are different, and perhaps better, than current drugs. These results provide evidence that agents targeting subsets of V-ATPases may prove useful in the clinic.
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Affiliation(s)
- L Shannon Holliday
- Departments of Orthodontics and Anatomy & Cell Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
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Hreniukh V, Bychkova S, Kulachkovsky O, Babsky A. Effect of bafilomycin and NAADP on membrane-associated ATPases and respiration of isolated mitochondria of the murine Nemeth-Kellner lymphoma. Cell Biochem Funct 2016; 34:579-587. [PMID: 27862060 DOI: 10.1002/cbf.3231] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 09/13/2016] [Accepted: 10/03/2016] [Indexed: 01/05/2023]
Abstract
The goal of the study was to estimate the effect of a selective V-type H+ -ATPase inhibitor bafilomycin A1 and nicotinic acid adenine dinucleotide phosphate (NAADP) on energetic processes in NK/Ly cell by directly measuring the respiration of isolated mitochondria and ATPase activities. NAADP (7 μM) increased the activity of Na+ /K+ -ATPase in the postmitochondrial fraction of NK/Ly cells, but lower concentration of NAADP decreased it (0.1 and 1 μM). The increase the activity of plasma membrane Ca2+ ATPase (PMCA) under NAADP application (1 and 7 μM) was observed. However, NAADP (1 μM) decreased activities of sarcoendoplasmic reticulum Ca2+ -ATPase (SERCA) and basal Mg2+ -ATPase. Bafilomycin A1 (1 μM) increased the activity of Na+ /K+ -ATPase and potentiated the effect of NAADP (1 μM) on this pump. At the same time, bafilomycin A1 (1 μM) completely prevented all effects of NAADP (1 μM) on activities of PMCA, SERCA, and basal Mg2+ -ATPase, confirming that these effects are dependent on acidic stores. Bafilomycin A1 or NAADP decreased respiratory and oxidative phosphorylation rates in NK/Ly mitochondria when α-ketoglutarate was used as substrate in contrast to succinate. Thus, α-ketoglutarate oxidation is more sensitive to bafilomycin A1 and NAADP influences compared with succinate oxidation. However, bafilomycin A1 + NAADP and any of these compounds separately lead to full uncoupling of mitochondria after ADP addition irrespectively to substrate used. Bafilomycin A1 affects isolated tumor mitochondria more effectively in combination with NAADP. Bafilomycin and NAADP alter some membrane-associated ATPases and inhibit respiration in mitochondria of the Nemeth-Kellner lymphoma. SIGNIFICANCE OF RESEARCH PARAGRAPH Bafilomycin A1 potentiates the effect of NAADP by inhibiting the mitochondrial energetic process in lymphoma cells and activity of Na+ /K+ -ATPase. The obtained data show promising possibility to use bafilomycin A1 and NAADP as chemotherapeutic agents for lymphoma cells treatment. This is important because lymphomas are seventh most common form of cancer. Today the lymphoma mortality is 15% to 30%, whereas the effectiveness of malignant neoplasms treatment is less than 50%.
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Affiliation(s)
- V Hreniukh
- Ivan Franko National University of Lviv, 4, Hrushevskyi St., Lviv, 79005, Ukraine
| | - S Bychkova
- Ivan Franko National University of Lviv, 4, Hrushevskyi St., Lviv, 79005, Ukraine
| | - O Kulachkovsky
- Ivan Franko National University of Lviv, 4, Hrushevskyi St., Lviv, 79005, Ukraine
| | - A Babsky
- Ivan Franko National University of Lviv, 4, Hrushevskyi St., Lviv, 79005, Ukraine
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Zadeh-Tahmasebi M, Bui P, Donini A. FLUID AND ION SECRETION BY MALPIGHIAN TUBULES OF LARVAL CHIRONOMIDS, Chironomus riparius: EFFECTS OF REARING SALINITY, TRANSPORT INHIBITORS, AND SEROTONIN. Arch Insect Biochem Physiol 2016; 93:67-85. [PMID: 27357470 DOI: 10.1002/arch.21342] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Larvae of Chironomus riparius respond to ion-poor and brackish water (IPW, BW) conditions by activating ion uptake mechanisms in the anal papillae and reducing ion absorption at the rectum, respectively. The role that the Malpighian tubules play in ion and osmoregulation under these conditions is not known in this species. This study examines rates of fluid secretion and major cation composition of secreted fluid from tubules of C. riparius reared in IPW, freshwater (FW) and BW. Fluid secretion of tubules from FW and BW larvae was similar but tubules from IPW larvae secrete fluid at higher rates, are more sensitive to serotonin stimulation, and the secreted fluid contains less Na(+) . Therefore in IPW, tubules work in concert with anal papillae to eliminate excess water while conserving Na(+) in the hemolymph. Tubules do not appear to play a significant role in ion/osmoregulation under BW. Serotonin immunoreactivity in the nervous system and gastrointestinal tract of larval C. riparius was similar to that seen in mosquito larvae with the exception that the hindgut was devoid of staining. Hemolymph serotonin titer was similar in FW and IPW; hence, serotonin is not responsible for the observed high rates of fluid secretion in IPW. Instead, it is suggested that serotonin may work in a synergistic manner with an unidentified hormonal factor in IPW. Ion transport mechanisms in the tubules of C. riparius are pharmacologically similar to those of other insects.
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Affiliation(s)
| | - Phuong Bui
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Andrew Donini
- Department of Biology, York University, Toronto, Ontario, Canada.
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11
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Pamarthy S, Jaiswal MK, Kulshreshtha A, Katara GK, Gilman-Sachs A, Beaman KD. The Vacuolar ATPase a2-subunit regulates Notch signaling in triple-negative breast cancer cells. Oncotarget 2016; 6:34206-20. [PMID: 26418877 PMCID: PMC4741446 DOI: 10.18632/oncotarget.5275] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 09/07/2015] [Indexed: 12/24/2022] Open
Abstract
Triple Negative Breast Cancer (TNBC) is a subtype of breast cancer with poor prognosis for which no targeted therapies are currently available. Notch signaling has been implicated in breast cancer but the factors that control Notch in TNBC are unknown. Because the Vacuolar ATPase has been shown to be important in breast cancer invasiveness, we investigated the role of a2-subunit isoform of Vacuolar ATPase (a2V) in regulating Notch signaling in TNBC. Confocal microscopy revealed that among all the ‘a’ subunit isoforms, a2V was uniquely expressed on the plasma membrane of breast cancer cells. Both a2V and NOTCH1 were elevated in TNBC tumors tissues and cell lines. a2V knockdown by siRNA as well as V-ATPase inhibition by Bafilomycin A1 (Baf A1) in TNBC cell lines enhanced Notch signaling by increasing the expression of Notch1 intracellular Domain (N1ICD). V-ATPase inhibition blocked NICD degradation by disrupting autophagy and lysosomal acidification as demonstrated by accumulation of LC3B and diminished expression of LAMP1 respectively. Importantly, treatment with Baf A1 or anti-a2V, a novel-neutralizing antibody against a2V hindered cell migration of TNBC cells. Our findings indicate that a2V regulates Notch signaling through its role in endolysosomal acidification and emerges as a potential target for TNBC.
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Affiliation(s)
- Sahithi Pamarthy
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Mukesh K Jaiswal
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Arpita Kulshreshtha
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Gajendra K Katara
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Alice Gilman-Sachs
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Kenneth D Beaman
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
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12
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Newton PT, Vuppalapati KK, Bouderlique T, Chagin AS. Pharmacological inhibition of lysosomes activates the MTORC1 signaling pathway in chondrocytes in an autophagy-independent manner. Autophagy 2016; 11:1594-607. [PMID: 26259639 PMCID: PMC4590675 DOI: 10.1080/15548627.2015.1068489] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Mechanistic target of rapamycin (serine/threonine kinase) complex 1 (MTORC1) is a protein-signaling complex at the fulcrum of anabolic and catabolic processes, which acts depending on wide-ranging environmental cues. It is generally accepted that lysosomes facilitate MTORC1 activation by generating an internal pool of amino acids. Amino acids activate MTORC1 by stimulating its translocation to the lysosomal membrane where it forms a super-complex involving the lysosomal-membrane-bound vacuolar-type H+-ATPase (v-ATPase) proton pump. This translocation and MTORC1 activation require functional lysosomes. Here we found that, in contrast to this well-accepted concept, in epiphyseal chondrocytes inhibition of lysosomal activity by v-ATPase inhibitors bafilomycin A1 or concanamycin A potently activated MTORC1 signaling. The activity of MTORC1 was visualized by phosphorylated forms of RPS6 (ribosomal protein S6) and EIF4EBP1, 2 well-known downstream targets of MTORC1. Maximal RPS6 phosphorylation was observed at 48-h treatment and reached as high as a 12-fold increase (p < 0.018). This activation of MTORC1 was further confirmed in bone organ culture and promoted potent stimulation of longitudinal growth (p < 0.001). Importantly, the same effect was observed in ATG5 (autophagy-related 5)-deficient bones suggesting a macroautophagy-independent mechanism of MTORC1 inhibition by lysosomes. Thus, our data show that in epiphyseal chondrocytes lysosomes inhibit MTORC1 in a macroautophagy-independent manner and this inhibition likely depends on v-ATPase activity.
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Affiliation(s)
- Phillip T Newton
- a Department of Physiology and Pharmacology ; Karolinska Institutet ; Stockholm , Sweden.,b Department of Women's and Children's Health ; Astrid Lindgren Children's Hospital; Karolinska University Hospital ; Stockholm , Sweden
| | - Karuna K Vuppalapati
- a Department of Physiology and Pharmacology ; Karolinska Institutet ; Stockholm , Sweden
| | - Thibault Bouderlique
- a Department of Physiology and Pharmacology ; Karolinska Institutet ; Stockholm , Sweden
| | - Andrei S Chagin
- a Department of Physiology and Pharmacology ; Karolinska Institutet ; Stockholm , Sweden.,b Department of Women's and Children's Health ; Astrid Lindgren Children's Hospital; Karolinska University Hospital ; Stockholm , Sweden
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Xu L, Beckebaum S, Iacob S, Wu G, Kaiser GM, Radtke A, Liu C, Kabar I, Schmidt HH, Zhang X, Lu M, Cicinnati VR. MicroRNA-101 inhibits human hepatocellular carcinoma progression through EZH2 downregulation and increased cytostatic drug sensitivity. J Hepatol 2014; 60:590-8. [PMID: 24211739 DOI: 10.1016/j.jhep.2013.10.028] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 10/17/2013] [Accepted: 10/29/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Oncogene polycomb group protein enhancer of zeste homolog 2 (EZH2) has been proposed to be a target gene of putative tumor suppressor microRNA-101 (miR-101). The aim of our study was to investigate the functional role of both miR-101 and EZH2 in human hepatocellular carcinoma (HCC). METHODS MiR-101 and EZH2 expressions were evaluated in tumor tissues of 99 HCC patients and 7 liver cancer cell lines by real-time PCR. Luciferase reporter assay was employed to validate whether EZH2 represents a target gene of miR-101. The effect of miR-101 on HCC growth as well as programmed cell death was studied in vitro and in vivo. RESULTS MiR-101 expression was significantly downregulated in most of HCC tissues and all cell lines, whereas EZH2 was significantly overexpressed in most of HCC tissues and all cell lines. There was a negative correlation between expression levels of miR-101 and EZH2. Luciferase assay results confirmed EZH2 as a direct target gene of miR-101, which negatively regulates EZH2 expression in HCC. Ectopic overexpression of miR-101 dramatically repressed proliferation, invasion, colony formation as well as cell cycle progression in vitro and suppressed tumorigenicity in vivo. Furthermore, miR-101 inhibited autophagy and synergized with either doxorubicin or fluorouracil to induce apoptosis in tumor cells. CONCLUSION Tumor suppressor miR-101 represses HCC progression through directly targeting EZH2 oncogene and sensitizes liver cancer cells to chemotherapeutic treatment. Our findings provide significant insights into molecular mechanisms of hepatocarcinogenesis and may have clinical relevance for the development of novel targeted therapies for HCC.
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14
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Lu C, Chen J, Xu HG, Zhou X, He Q, Li YL, Jiang G, Shan Y, Xue B, Zhao RX, Wang Y, Werle KD, Cui R, Liang J, Xu ZX. MIR106B and MIR93 prevent removal of bacteria from epithelial cells by disrupting ATG16L1-mediated autophagy. Gastroenterology 2014; 146:188-99. [PMID: 24036151 PMCID: PMC3870037 DOI: 10.1053/j.gastro.2013.09.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 08/14/2013] [Accepted: 09/07/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Variants in genes that regulate autophagy have been associated with Crohn's disease (CD). Defects in autophagy-mediated removal of pathogenic microbes could contribute to the pathogenesis of CD. We investigated the role of the microRNAs (miRs) MIR106B and MIR93 in induction of autophagy and bacterial clearance in human cell lines and the correlation between MIR106B and autophagy-related gene 16L1 (ATG16L1) expression in tissues from patients with CD. METHODS We studied the ability of MIR106B and MIR93 to regulate ATG transcripts in human cancer cell lines (HCT116, SW480, HeLa, and U2OS) using luciferase report assays and bioinformatics analyses; MIR106B and MIR93 mimics and antagonists were transfected into cells to modify levels of miRs. Cells were infected with LF82, a CD-associated adherent-invasive strain of Escherichia coli, and monitored by confocal microscopy and for colony-forming units. Colon tissues from 41 healthy subjects (controls), 22 patients with active CD, 16 patients with inactive CD, and 7 patients with chronic inflammation were assessed for levels of MIR106B and ATG16L1 by in situ hybridization and immunohistochemistry. RESULTS Silencing Dicer1, an essential processor of miRs, increased levels of ATG protein and formation of autophagosomes in cells, indicating that miRs regulate autophagy. Luciferase reporter assays indicated that MIR106B and MIR93 targeted ATG16L1 messenger RNA. MIR106B and MIR93 reduced levels of ATG16L1 and autophagy; these increased after expression of ectopic ATG16L1. In contrast, MIR106B and MIR93 antagonists increased formation of autophagosomes. Levels of MIR106B were increased in intestinal epithelia from patients with active CD, whereas levels of ATG16L1 were reduced compared with controls. Levels of c-Myc were also increased in intestinal epithelia of patients with active CD compared with controls. These alterations could impair removal of CD-associated bacteria by autophagy. CONCLUSIONS In human cell lines, MIR106B and MIR93 reduce levels of ATG16L1 and autophagy and prevent autophagy-dependent eradication of intracellular bacteria. This process also appears to be altered in colon tissues from patients with active CD.
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Affiliation(s)
- Changming Lu
- Division of Hematology and Oncology, Comprehensive Cancer Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jianfeng Chen
- Division of Hematology and Oncology, Comprehensive Cancer Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Hua-Guo Xu
- Division of Hematology and Oncology, Comprehensive Cancer Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Xianzheng Zhou
- Department of Pediatrics, the University of Minnesota, Minneapolis, Minnesota, USA,Departments of Pediatrics, Microbiology and Immunology, and Cell Biology and Anatomy, New York Medical College, Valhalla, New York, USA
| | - Qiongqiong He
- Department of Pathology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Yu-Lin Li
- Key Laboratory of Pathobiology, Ministry of Education, Norman Bethune College of Medicine, Jilin University, Changchun, Jilin, China
| | - Guoqing Jiang
- Department of Surgery, 2nd Affiliated Hospital, Soochow University, Suzhou, Jiangsu, China
| | - Yuxi Shan
- Department of Surgery, 2nd Affiliated Hospital, Soochow University, Suzhou, Jiangsu, China
| | - Boxin Xue
- Department of Surgery, 2nd Affiliated Hospital, Soochow University, Suzhou, Jiangsu, China
| | - Rui-Xun Zhao
- Division of Hematology and Oncology, Comprehensive Cancer Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Yong Wang
- Division of Hematology and Oncology, Comprehensive Cancer Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kaitlin D. Werle
- Division of Hematology and Oncology, Comprehensive Cancer Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Rutao Cui
- Department of Dermatology, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jiyong Liang
- Department of Systems Biology, UT MD Anderson Cancer Center, Texas, USA
| | - Zhi-Xiang Xu
- Division of Hematology and Oncology, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama.
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15
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Zhang W, Fortman JL, Carlson JC, Yan J, Liu Y, Bai F, Guan W, Jia J, Matainaho T, Sherman DH, Li S. Characterization of the bafilomycin biosynthetic gene cluster from Streptomyces lohii. Chembiochem 2013; 14:301-6. [PMID: 23362147 PMCID: PMC3771327 DOI: 10.1002/cbic.201200743] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Indexed: 11/08/2022]
Abstract
New hope for old bones: The plecomacrolide bafilomycin has been explored for decades as an anti-osteoporotic. However, its structural complexity has limited the synthesis of analogues. The cloning of the bafilomycin biosynthetic gene cluster from the environmental isolate Streptomyces lohii opens the door to the production of new analogues through bioengineering.
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Affiliation(s)
- Wei Zhang
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, Shandong 266101 (P. R. China), Fax: (+86)-532-8066-2778
| | - J. L. Fortman
- Life Sciences Institute, Departments of Medicinal Chemistry, Chemistry, and Microbiology and Immunology University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA), Fax: (+1)-734-615-3641
| | - Jacob C. Carlson
- Life Sciences Institute, Departments of Medicinal Chemistry, Chemistry, and Microbiology and Immunology University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA), Fax: (+1)-734-615-3641
| | - Jiyong Yan
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, Shandong 266101 (P. R. China), Fax: (+86)-532-8066-2778
| | - Yi Liu
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, Shandong 266101 (P. R. China), Fax: (+86)-532-8066-2778
| | - Fali Bai
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, Shandong 266101 (P. R. China), Fax: (+86)-532-8066-2778
| | - Wenna Guan
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, Shandong 266101 (P. R. China), Fax: (+86)-532-8066-2778
| | - Junyong Jia
- Life Sciences Institute, Departments of Medicinal Chemistry, Chemistry, and Microbiology and Immunology University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA), Fax: (+1)-734-615-3641
| | - Teatulohi Matainaho
- Professor Teatulohi Matainaho, Department of Pharmacology, University of Papua New Guinea, Port Morseby (Papua New Guinea)
| | - David H. Sherman
- Life Sciences Institute, Departments of Medicinal Chemistry, Chemistry, and Microbiology and Immunology University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA), Fax: (+1)-734-615-3641
| | - Shengying Li
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao, Shandong 266101 (P. R. China), Fax: (+86)-532-8066-2778
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16
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Machado JD, Camacho M, Alvarez J, Borges R. On the role of intravesicular calcium in the motion and exocytosis of secretory organelles. Commun Integr Biol 2011; 2:71-3. [PMID: 19704891 DOI: 10.4161/cib.7467] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Accepted: 11/20/2008] [Indexed: 11/19/2022] Open
Abstract
Secretory vesicles of sympathetic neurons and chromaffin granules maintain a pH gradient towards the cytosol (5.5 vs. 7.2) promoted by the V-ATPase activity. This gradient of pH is mainly responsible for the accumulation of amines. The secretory vesicles contain large amounts of total Ca(2+), but the free intragranular [Ca(2+)], the mechanisms for Ca(2+) uptake and release from the granules and their physiological relevance regarding exocytosis are still matters of debate.We have recently shown that disruption of the pH gradient of secretory vesicles slowed down exocytosis. Fluorimetric measurements, using the dye Oregon green BAPTA-2, showed that the V-ATPase inhibitor bafilomycin A1 directly released Ca(2+) from freshly isolated vesicles. Accordingly, vesicle alkalinization released Ca(2+) from the granules to the cytosol, measured with fura-2 in intact chromaffin cells. Using TIRFM in cells overexpressing the EGFP-labeled synaptobrevin (VAMP2-EGFP) protein, we have then shown that the Ca(2+) released from the vesicles to the cytosol in the presence of bafilomycin, dramatically increased the granule motion of chromaffin- or PC12-derived granules, and triggered exocytosis (measured by amperometry).We conclude that the gradient of pH of secretory vesicles might be involved in the homeostatic regulation of the local cytosolic Ca(2+) around the vesicles and in two of the major functions of secretory cells, vesicle motion and exocytosis.1.
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Affiliation(s)
- José D Machado
- Unidad de Farmacología; Facultad de Medicina; Universidad de La Laguna Tenerife; La Laguna, Spain
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17
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Uchiyama A, Kim JS, Kon K, Jaeschke H, Ikejima K, Watanabe S, Lemasters JJ. Translocation of iron from lysosomes into mitochondria is a key event during oxidative stress-induced hepatocellular injury. Hepatology 2008; 48:1644-54. [PMID: 18846543 PMCID: PMC2579320 DOI: 10.1002/hep.22498] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
UNLABELLED Iron overload exacerbates various liver diseases. In hepatocytes, a portion of non-heme iron is sequestered in lysosomes and endosomes. The precise mechanisms by which lysosomal iron participates in hepatocellular injury remain uncertain. Here, our aim was to determine the role of intracellular movement of chelatable iron in oxidative stress-induced killing to cultured hepatocytes from C3Heb mice and Sprague-Dawley rats. Mitochondrial polarization and chelatable iron were visualized by confocal microscopy of tetramethylrhodamine methylester (TMRM) and quenching of calcein, respectively. Cell viability and hydroperoxide formation (a measure of lipid peroxidation) were measured fluorometrically using propidium iodide and chloromethyl dihydrodichlorofluorescein, respectively. After collapse of lysosomal/endosomal acidic pH gradients with bafilomycin (50 nM), an inhibitor of the vacuolar proton-pumping adenosine triphosphatase, cytosolic calcein fluorescence became quenched. Deferoxamine mesylate and starch-deferoxamine (1 mM) prevented bafilomycin-induced calcein quenching, indicating that bafilomycin induced release of chelatable iron from lysosomes/endosomes. Bafilomycin also quenched calcein fluorescence in mitochondria, which was blocked by 20 microM Ru360, an inhibitor of the mitochondrial calcium uniporter, consistent with mitochondrial iron uptake by the uniporter. Bafilomycin alone was not sufficient to induce mitochondrial depolarization and cell killing, but in the presence of low-dose tert-butylhydroperoxide (25 microM), bafilomycin enhanced hydroperoxide generation, leading to mitochondrial depolarization and subsequent cell death. CONCLUSION Taken together, the results are consistent with the conclusion that bafilomycin induces release of chelatable iron from lysosomes/endosomes, which is taken up by mitochondria. Oxidative stress and chelatable iron thus act as two "hits" synergistically promoting toxic radical formation, mitochondrial dysfunction, and cell death. This pathway of intracellular iron translocation is a potential therapeutic target against oxidative stress-mediated hepatotoxicity.
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Affiliation(s)
- Akira Uchiyama
- Department of Pharmaceutical & Biomedical Sciences, Medical University of South Carolina, Charleston, SC, USA,Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan
| | - Jae-Sung Kim
- Department of Surgery, University of Florida, Gainesville, FL, USA
| | - Kazuyoshi Kon
- Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan
| | - Hartmut Jaeschke
- Department of Pharmacology, Toxicology & Therapeutics, University of Kansas Medical Center, Kansas City, Kansas
| | - Kenichi Ikejima
- Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan
| | - Sumio Watanabe
- Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan
| | - John J. Lemasters
- Department of Pharmaceutical & Biomedical Sciences, Medical University of South Carolina, Charleston, SC, USA,Department of Biochemistry & Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
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18
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López J, Camello-Almaraz C, Pariente J, Salido G, Rosado J. Ca2+ accumulation into acidic organelles mediated by Ca2+- and vacuolar H+-ATPases in human platelets. Biochem J 2005; 390:243-52. [PMID: 15847604 PMCID: PMC1188269 DOI: 10.1042/bj20050168] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Revised: 04/19/2005] [Accepted: 04/22/2005] [Indexed: 11/17/2022]
Abstract
Most physiological agonists increase cytosolic free [Ca2+]c (cytosolic free Ca2+ concentration) to regulate a variety of cellular processes. How different stimuli evoke distinct spatiotemporal Ca2+ responses remains unclear, and the presence of separate intracellular Ca2+ stores might be of great functional relevance. Ca2+ accumulation into intracellular compartments mainly depends on the activity of Ca2+- and H+-ATPases. Platelets present two separate Ca2+ stores differentiated by the distinct sensitivity to thapsigargin and TBHQ [2,5-di-(t-butyl)-1,4-hydroquinone]. Although one store has long been identified as the dense tubular system, the nature of the TBHQ-sensitive store remains uncertain. Treatment of platelets with GPN (glycylphenylalanine-2-naphthylamide) impaired Ca2+ release by TBHQ and reduced that evoked by thrombin. In contrast, GPN did not modify Ca2+ mobilization stimulated by ADP or AVP ([arginine]vasopressin). Treatment with nigericin, a proton carrier, and bafilomycin A1, an inhibitor of the vacuolar H+-ATPase, to dissipate the proton gradient into acidic organelles induces a transient increase in [Ca2+]c that was abolished by previous treatment with the SERCA (sarcoplasmic/endoplasmic-reticulum Ca2+-ATPase) 3 inhibitor TBHQ. Depleted acidic stores after nigericin or bafilomycin A1 were refilled by SERCA 3. Thrombin, but not ADP or AVP, reduces the rise in [Ca2+]c evoked by nigericin and bafilomycin A1. Our results indicate that the TBHQ-sensitive store in human platelets is an acidic organelle whose Ca2+ accumulation is regulated by both Ca2+- and vacuolar H+-ATPases.
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Key Words
- acidic organelles
- bafilomycin
- calcium stores
- nigericin
- platelets
- thrombin
- avp, [arginine]vasopressin
- [ca2+]c, cytosolic free calcium concentration
- er, endoplasmic reticulum
- gpn, glycylphenylalanine 2-naphthylamide
- hbs, hepes-buffered saline
- pmca, plasma-membrane ca2+ atpase
- serca 3, sarcoplasmic/endoplasmic-reticulum ca2+-atpase
- tbhq, 2,5-di-(t-butyl)-1,4-hydroquinone
- tg, thapsigargin
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Affiliation(s)
- José J. López
- Department of Physiology, University of Extremadura, 10071 Cáceres, Spain
| | | | - José A. Pariente
- Department of Physiology, University of Extremadura, 10071 Cáceres, Spain
| | - Ginés M. Salido
- Department of Physiology, University of Extremadura, 10071 Cáceres, Spain
| | - Juan A. Rosado
- Department of Physiology, University of Extremadura, 10071 Cáceres, Spain
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Khanna A, Simoni J, Hacker C, Duran MJ, Wesson DE. Increased endothelin activity mediates augmented distal nephron acidification induced by dietary protein. Trans Am Clin Climatol Assoc 2005; 116:239-56; discussion 257-8. [PMID: 16555618 PMCID: PMC1473158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We tested the hypothesis that increased dietary protein augments distal nephron acidification through an endothelin-dependent mechanism. Munich-Wistar rats ate minimum electrolyte diets of 50% (HiPro) and 20% (CON) casein-provided protein, the latter comparable to standard chow. HiPro vs. CON had higher distal nephron H+ secretion (41.3 +/- 4.0 vs. 23.0 +/- 2.1 pmol/mm.min, p < 0.002) mediated by augmented Na+/H+ exchange and H(+)-ATPase activity. Renal cortex of HiPro vs. CON had higher ET-1 addition to microdialysate and higher ET-1 mRNA, consistent with increased renal ET-1 production. Bosentan, an endothelin A/B receptor antagonist, decreased HiPro distal nephron H+ secretion (28.4 +/- 2.4 vs. 41.3 +/- 4.0 pmol/mm.min, p < 0.016) through decreased Na+/H+ exchange and decreased H(+)-ATPase activity. Increased dietary protein augments distal nephron acidification through an endothelin-sensitive increase in Na+/H+ exchange and H(+)-ATPase activity, supporting an endothelin role in the distal nephron response to this common challenge to acid-base status.
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Affiliation(s)
- Apurv Khanna
- From the Texas Tech University Health Sciences Center, Department of Internal Medicine, Texas Tech University School of Medicine, Lubbock, Texas
| | - Jan Simoni
- From the Texas Tech University Health Sciences Center, Department of Surgery, Texas Tech University School of Medicine, Lubbock, Texas
| | - Callenda Hacker
- From the Texas Tech University Health Sciences Center, Department of Internal Medicine, Texas Tech University School of Medicine, Lubbock, Texas
| | - Marie-Josée Duran
- From the Texas Tech University Health Sciences Center, Department of Physiology, Texas Tech University School of Medicine, Lubbock, Texas
| | - Donald E Wesson
- From the Texas Tech University Health Sciences Center, Department of Internal Medicine, Texas Tech University School of Medicine, Lubbock, Texas
- From the Texas Tech University Health Sciences Center, Department of Physiology, Texas Tech University School of Medicine, Lubbock, Texas
- Principle author's information: Donald E. Wesson, M.D., Texas Tech University Health Sciences Center, Renal Section, 3601 Fourth Street, Lubbock, TX 79430(806) 743-3107(806) 743-3177
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Araque A, Li N, Doyle RT, Haydon PG. SNARE protein-dependent glutamate release from astrocytes. J Neurosci 2000; 20:666-73. [PMID: 10632596 PMCID: PMC6772413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
We investigated the cellular mechanisms underlying the Ca(2+)-dependent release of glutamate from cultured astrocytes isolated from rat hippocampus. Using Ca(2+) imaging and electrophysiological techniques, we analyzed the effects of disrupting astrocytic vesicle proteins on the ability of astrocytes to release glutamate and to cause neuronal electrophysiological responses, i.e., a slow inward current (SIC) and/or an increase in the frequency of miniature synaptic currents. We found that the Ca(2+)-dependent glutamate release from astrocytes is not caused by the reverse operation of glutamate transporters, because the astrocyte-induced glutamate-mediated responses in neurons were affected neither by inhibitors of glutamate transporters (beta-threo-hydroxyaspartate, dihydrokainate, and L-trans-pyrrolidine-2,4-dicarboxylate) nor by replacement of extracellular sodium with lithium. We show that Ca(2+)-dependent glutamate release from astrocytes requires an electrochemical gradient necessary for glutamate uptake in vesicles, because bafilomycin A(1), a vacuolar-type H(+)-ATPase inhibitor, reduced glutamate release from astrocytes. Injection of astrocytes with the light chain of the neurotoxin Botulinum B that selectively cleaves the vesicle-associated SNARE protein synaptobrevin inhibited the astrocyte-induced glutamate response in neurons. Therefore, the Ca(2+)-dependent glutamate release from astrocytes is a SNARE protein-dependent process that requires the presence of functional vesicle-associated proteins, suggesting that astrocytes store glutamate in vesicles and that it is released through an exocytotic pathway.
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Affiliation(s)
- A Araque
- Laboratory of Cellular Signaling, Department of Zoology and Genetics, Iowa State University, Ames, Iowa 50011, USA.
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