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Naima J, Ohta Y. Potassium Ions Decrease Mitochondrial Matrix pH: Implications for ATP Production and Reactive Oxygen Species Generation. Int J Mol Sci 2024; 25:1233. [PMID: 38279231 PMCID: PMC10815940 DOI: 10.3390/ijms25021233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 01/05/2024] [Accepted: 01/14/2024] [Indexed: 01/28/2024] Open
Abstract
Potassium (K+) is the most abundant cation in the cytosol and is maintained at high concentrations within the mitochondrial matrix through potassium channels. However, many effects of K+ at such high concentrations on mitochondria and the underlying mechanisms remain unclear. This study aims to elucidate these effects and mechanisms by employing fluorescence imaging techniques to distinguish and precisely measure signals inside and outside the mitochondria. We stained the mitochondrial matrix with fluorescent dyes sensitive to K+, pH, reactive oxygen species (ROS), and membrane potential in plasma membrane-permeabilized C6 cells and isolated mitochondria from C6 cells. Fluorescence microscopy facilitated the accurate measurement of fluorescence intensity inside and outside the matrix. Increasing extramitochondrial K+ concentration from 2 mM to 127 mM led to a reduction in matrix pH and a decrease in the generation of highly reactive ROS. In addition, elevated K+ levels electrically polarized the inner membrane of the mitochondria and promoted efficient ATP synthesis via FoF1-ATPase. Introducing protons (H+) into the matrix through phosphate addition led to further mitochondrial polarization, and this effect was more pronounced in the presence of K+. K+ at high concentrations, reaching sub-hundred millimolar levels, increased H+ concentration within the matrix, suppressing ROS generation and boosting ATP synthesis. Although this study does not elucidate the role of specific types of potassium channels in mitochondria, it does suggest that mitochondrial K+ plays a beneficial role in maintaining cellular health.
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Affiliation(s)
| | - Yoshihiro Ohta
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Nakacho, Koganei, Tokyo 184-8588, Japan;
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2
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Wu J, Jin M, Tran Q, Kim M, Kim SI, Shin J, Park H, Shin N, Kang H, Shin HJ, Lee SY, Cui SB, Lee CJ, Lee WH, Kim DW. Employing the sustained-release properties of poly(lactic-co-glycolic acid) nanoparticles to reveal a novel mechanism of sodium-hydrogen exchanger 1 in neuropathic pain. Transl Res 2024; 263:53-72. [PMID: 37678757 DOI: 10.1016/j.trsl.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/16/2023] [Accepted: 09/01/2023] [Indexed: 09/09/2023]
Abstract
Neuropathic pain is caused by injury or disease of the somatosensory system, and its course is usually chronic. Several studies have been dedicated to investigating neuropathic pain-related targets; however, little attention has been paid to the persistent alterations that these targets, some of which may be crucial to the pathophysiology of neuropathic pain. The present study aimed to identify potential targets that may play a crucial role in neuropathic pain and validate their long-term impact. Through bioinformatics analysis of RNA sequencing results, we identified Slc9a1 and validated the reduced expression of sodium-hydrogen exchanger 1 (NHE1), the protein that Slc9a1 encodes, in the spinal nerve ligation (SNL) model. Colocalization analysis revealed that NHE1 is primarily co-localized with vesicular glutamate transporter 2-positive neurons. In vitro experiments confirmed that poly(lactic-co-glycolic acid) nanoparticles loaded with siRNA successfully inhibited NHE1 in SH-SY5Y cells, lowered intracellular pH, and increased intracellular calcium concentrations. In vivo experiments showed that sustained suppression of spinal NHE1 expression by siRNA-loaded nanoparticles resulted in delayed hyperalgesia in naïve and SNL model rats, whereas amiloride-induced transient suppression of NHE1 expression yielded no significant changes in pain sensitivity. We identified Slc9a1, which encodes NHE1, as a key gene in neuropathic pain. Utilizing the sustained release properties of nanoparticles enabled us to elucidate the chronic role of decreased NHE1 expression, establishing its significance in the mechanisms of neuropathic pain.
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Affiliation(s)
- Junhua Wu
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Neurology, Yanji Hospital, Yanji, China
| | - Meiling Jin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Quangdon Tran
- Molecular Biology Laboratory, Department of Medical Laboratories, Hai Phong International Hospital, Hai Phong City, Vietnam
| | - Minwoo Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Song I Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Juhee Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Hyewon Park
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Nara Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Hyunji Kang
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Hyo Jung Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Sun Yeul Lee
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anesthesia and Pain Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Song-Biao Cui
- Department of Neurology, Affiliated Hospital of Yanbian University, Yanji, China
| | - C Justin Lee
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Won Hyung Lee
- Department of Anesthesia and Pain Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea.
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3
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Holland SM, Gallo G. Actin cytoskeletal dynamics do not impose an energy drain on growth cone bioenergetics. J Cell Sci 2023; 136:jcs261356. [PMID: 37534394 PMCID: PMC10445737 DOI: 10.1242/jcs.261356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/26/2023] [Indexed: 08/04/2023] Open
Abstract
The regulation of the intracellular level of ATP is a fundamental aspect of bioenergetics. Actin cytoskeletal dynamics have been reported to be an energetic drain in developing neurons and platelets. We addressed the role of actin dynamics in primary embryonic chicken neurons using luciferase assays, and by measurement of the ATP/ADP ratio using the ratiometric reporter PercevalHR and the ATP level using the ratiometric reporter mRuby-iATPSnFR. None of the methods revealed an effect of suppressing actin dynamics on the decline in the neuronal ATP level or the ATP/ADP ratio following shutdown of ATP production. Similarly, we find that treatments that elevate or suppress actin dynamics do not alter the ATP/ADP ratio in growth cones, the subcellular domain with the highest actin dynamics in developing neurons. Collectively, the data indicate that actin cytoskeletal dynamics are not a significant energy drain in developing neurons and that the ATP/ADP ratio is maintained when energy utilization varies. Discrepancies between prior work and the current data are discussed with emphasis on methodology and interpretation of the data.
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Affiliation(s)
- Sabrina M. Holland
- Lewis Katz School of Medicine at Temple University, Department of Neural Sciences, Shriners Pediatric Research Center, 3500 North Broad St, Philadelphia, PA 19140, USA
| | - Gianluca Gallo
- Lewis Katz School of Medicine at Temple University, Department of Neural Sciences, Shriners Pediatric Research Center, 3500 North Broad St, Philadelphia, PA 19140, USA
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Hu W, Gu H, Wang K, Lu Z, Li X, Cong R, Ren T, Lu J. Potassium deficiency stress reduces Rubisco activity in Brassica napus leaves by subcellular acidification decreasing photosynthetic rate. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 201:107912. [PMID: 37523826 DOI: 10.1016/j.plaphy.2023.107912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 07/17/2023] [Accepted: 07/24/2023] [Indexed: 08/02/2023]
Abstract
Under potassium (K) deficiency photosynthetic carboxylation capacities are limited, affecting the photosynthetic rate of plants. However, it is not clear how ionic K within plants regulates carboxylation capacities. Therefore, the photosynthetic rate (A), ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) characteristics, and cytoplasmic pH of Brassica napus leaves with different K levels were measured to evaluate the effects of K on the carboxylation capacity by regulating subcellular pH. The results showed that biochemical limitation dominates the decrease of A. There was a close positive correlation between A and the Rubisco maximum carboxylation rate (Vcmax), which was closer than that between A and the maximum electron transport rate. The thresholds of leaf K concentrations causing decreased A, Vcmax, and Rubisco initial activity were consistent and close to 1.0% in the hydroponic experiments and 1.2% in the field experiments. K deficiency resulted in decreased Rubisco activity, which reduced carboxylation capacity. Moreover, the Rubisco initial activities in vitro with sufficient K supply or under K deficiency all were significantly reduced when the pH was decreased. The cytoplasmic pH was kept neutral at 7.5 under sufficient K supply, and decreased as the leaf K concentration declined below the threshold. Acidified cytoplasmic environment caused by K deficiency could not maintain the pH balance of the chloroplasts, leading to decreased Rubisco initial activity and photosynthetic capacity.
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Affiliation(s)
- Wenshi Hu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China; Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China
| | - Hehe Gu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Kunjiao Wang
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhifeng Lu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiaokun Li
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Rihuan Cong
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Tao Ren
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Jianwei Lu
- College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
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Rombolá-Caldentey B, Mendoza I, Quintero FJ, Pardo JM. Structure-Guided Identification of Critical Residues in the Vacuolar Cation/Proton Antiporter NHX1 from Arabidopsis thaliana. PLANTS (BASEL, SWITZERLAND) 2023; 12:2778. [PMID: 37570932 PMCID: PMC10421325 DOI: 10.3390/plants12152778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/24/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023]
Abstract
Cation/Proton Antiporters (CPA) acting in all biological membranes regulate the volume and pH of cells and of intracellular organelles. A key issue with these proteins is their structure-function relationships since they present intrinsic regulatory features that rely on structural determinants, including pH sensitivity and the stoichiometry of ion exchange. Crystal structures are only available for prokaryotic CPA, whereas the eukaryotic ones have been modeled using the former as templates. Here, we present an updated and improved structural model of the tonoplast-localized K+, Na+/H+ antiporter NHX1 of Arabidopsis as a representative of the vacuolar NHX family that is essential for the accumulation of K+ into plant vacuoles. Conserved residues that were judged as functionally important were mutated, and the resulting protein variants were tested for activity in the yeast Saccharomyces cerevisiae. The results indicate that residue N184 in the ND-motif characteristic of CPA1 could be replaced by the DD-motif of CPA2 family members with minimal consequences for their activity. Attempts to alter the electroneutrality of AtNHX1 by different combinations of amino acid replacements at N184, R353 and R390 residues resulted in inactive or partly active proteins with a differential ability to control the vacuolar pH of the yeast.
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Affiliation(s)
| | | | | | - José M. Pardo
- Instituto de Bioquimica Vegetal y Fotosintesis, cicCartuja, Consejo Superior de Investigaciones Cientificas, Universidad de Sevilla, 41092 Sevilla, Spain; (B.R.-C.); (I.M.); (F.J.Q.)
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Villanueva JA, Crooks AL, Nagy TA, Quintana JLJ, Dalebroux ZD, Detweiler CS. Salmonella enterica Infections Are Disrupted by Two Small Molecules That Accumulate within Phagosomes and Differentially Damage Bacterial Inner Membranes. mBio 2022; 13:e0179022. [PMID: 36135367 PMCID: PMC9601186 DOI: 10.1128/mbio.01790-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 09/06/2022] [Indexed: 11/23/2022] Open
Abstract
Gram-negative bacteria have a robust cell envelope that excludes or expels many antimicrobial agents. However, during infection, host soluble innate immune factors permeabilize the bacterial outer membrane. We identified two small molecules that exploit outer membrane damage to access the bacterial cell. In standard microbiological media, neither compound inhibited bacterial growth nor permeabilized bacterial outer membranes. In contrast, at micromolar concentrations, JAV1 and JAV2 enabled the killing of an intracellular human pathogen, Salmonella enterica serovar Typhimurium. S. Typhimurium is a Gram-negative bacterium that resides within phagosomes of cells from the monocyte lineage. Under broth conditions that destabilized the lipopolysaccharide layer, JAV2 permeabilized the bacterial inner membrane and was rapidly bactericidal. In contrast, JAV1 activity was more subtle: JAV1 increased membrane fluidity, altered reduction potential, and required more time than JAV2 to disrupt the inner membrane barrier and kill bacteria. Both compounds interacted with glycerophospholipids from Escherichia coli total lipid extract-based liposomes. JAV1 preferentially interacted with cardiolipin and partially relied on cardiolipin production for activity, whereas JAV2 generally interacted with lipids and had modest affinity for phosphatidylglycerol. In mammalian cells, neither compound significantly altered mitochondrial membrane potential at concentrations that killed S. Typhimurium. Instead, JAV1 and JAV2 became trapped within acidic compartments, including macrophage phagosomes. Both compounds improved survival of S. Typhimurium-infected Galleria mellonella larvae. Together, these data demonstrate that JAV1 and JAV2 disrupt bacterial inner membranes by distinct mechanisms and highlight how small, lipophilic, amine-substituted molecules can exploit host soluble innate immunity to facilitate the killing of intravesicular pathogens. IMPORTANCE Innovative strategies for developing new antimicrobials are needed. Combining our knowledge of host-pathogen interactions and relevant drug characteristics has the potential to reveal new approaches to treating infection. We identified two compounds with antibacterial activity specific to infection and with limited host cell toxicity. These compounds appeared to exploit host innate immunity to access the bacterium and differentially damage the bacterial inner membrane. Further, both compounds accumulated within Salmonella-containing and other acidic vesicles, a process known as lysosomal trapping, which protects the host and harms the pathogen. The compounds also increased host survival in an insect infection model. This work highlights the ability of host innate immunity to enable small molecules to act as antibiotics and demonstrates the feasibility of antimicrobial targeting of the inner membrane. Additionally, this study features the potential use of lysosomal trapping to enhance the activities of compounds against intravesicular pathogens.
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Affiliation(s)
- Joseph A. Villanueva
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Amy L. Crooks
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Toni A. Nagy
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Joaquin L. J. Quintana
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Zachary D. Dalebroux
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Corrella S. Detweiler
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
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pH Modulation in Adhesive Cells with a Protonic Biotransducer. Bioelectrochemistry 2022; 147:108202. [DOI: 10.1016/j.bioelechem.2022.108202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 06/26/2022] [Accepted: 06/29/2022] [Indexed: 11/18/2022]
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8
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Yoneda M, Aklima J, Ohsawa I, Ohta Y. Effects of proton pumping on the structural rigidity of cristae in mitochondria. Arch Biochem Biophys 2022; 720:109172. [PMID: 35276212 DOI: 10.1016/j.abb.2022.109172] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 03/06/2022] [Accepted: 03/07/2022] [Indexed: 02/08/2023]
Abstract
Mitochondria change their morphology and inner membrane structure depending on their activity. Since mitochondrial activity also depends on their structure, it is important to elucidate the interrelationship between the activity and structure of mitochondria. However, the mechanism by which mitochondrial activity affects the structure of cristae, the folded structure of the inner membrane, is not well understood. In this study, the effect of the mitochondrial activity on the cristae structure was investigated by examining the structural rigidity of cristae. Taking advantage of the fact that unfolding of cristae induces mitochondrial swelling, we investigated the relationship between mitochondrial activity and the susceptibility to swelling. The swelling of individual isolated mitochondria exposed to a hypotonic solution was observed with an optical microscope. The presence of respiratory substrates (malate and glutamate) increased the percentage of mitochondria that underwent swelling, and the further addition of rotenone or KCN (inhibitors of proton pumps) reversed the increase. In the absence of respiratory substrates, acidification of the buffer surrounding the mitochondria also increased the percentage of swollen mitochondria. These observations suggest that acidification of the outer surface of inner membranes, especially intracristal space, by proton translocation from the matrix to the intracristal space, decreases the structural rigidity of the cristae. This interpretation was verified by the observation that ADP or CCCP, which induces proton re-entry to the matrix, suppressed the mitochondrial swelling in the presence of respiratory substrates. The addition of CCCP to the cells induced a morphological change in mitochondria from an initial elongated structure to a largely curved structure at pH 7.4, but there were no morphological changes when the pH of the cytosol dropped to 6.2. These results suggest that a low pH in the intracristal space may be helpful in maintaining the elongated structure of mitochondria. The present study shows that proton pumping by the electron transfer chain is the mechanism underlying mitochondrial morphology and the flexibility of cristae structure.
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Affiliation(s)
- Mayu Yoneda
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan
| | - Jannatul Aklima
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan; Department of Biochemistry & Molecular Biology, University of Chittagong, Chittagong, 4331, Bangladesh
| | - Ikuroh Ohsawa
- Biological Process of Aging, Tokyo Metropolitan Institute of Gerontology, Itabashi, Tokyo, 173-0015, Japan
| | - Yoshihiro Ohta
- Division of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan.
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Mantovanelli L, Gaastra BF, Poolman B. Fluorescence-based sensing of the bioenergetic and physicochemical status of the cell. CURRENT TOPICS IN MEMBRANES 2021; 88:1-54. [PMID: 34862023 DOI: 10.1016/bs.ctm.2021.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fluorescence-based sensors play a fundamental role in biological research. These sensors can be based on fluorescent proteins, fluorescent probes or they can be hybrid systems. The availability of a very large dataset of fluorescent molecules, both genetically encoded and synthetically produced, together with the structural insights on many sensing domains, allowed to rationally design a high variety of sensors, capable of monitoring both molecular and global changes in living cells or in in vitro systems. The advancements in the fluorescence-imaging field helped researchers to obtain a deeper understanding of how and where specific changes occur in a cell or in vitro by combining the readout of the fluorescent sensors with the spatial information provided by fluorescent microscopy techniques. In this review we give an overview of the state of the art in the field of fluorescent biosensors and fluorescence imaging techniques, and eventually guide the reader through the choice of the best combination of fluorescent tools and techniques to answer specific biological questions. We particularly focus on sensors for probing the bioenergetics and physicochemical status of the cell.
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Affiliation(s)
- Luca Mantovanelli
- Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Bauke F Gaastra
- Department of Biochemistry, University of Groningen, Groningen, the Netherlands
| | - Bert Poolman
- Department of Biochemistry, University of Groningen, Groningen, the Netherlands.
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Staphylococcal Bacterial Persister Cells, Biofilms, and Intracellular Infection Are Disrupted by JD1, a Membrane-Damaging Small Molecule. mBio 2021; 12:e0180121. [PMID: 34634935 PMCID: PMC8510524 DOI: 10.1128/mbio.01801-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Rates of antibiotic and multidrug resistance are rapidly rising, leaving fewer options for successful treatment of bacterial infections. In addition to acquiring genetic resistance, many pathogens form persister cells, form biofilms, and/or cause intracellular infections that enable bacteria to withstand antibiotic treatment and serve as a source of recurring infections. JD1 is a small molecule previously shown to kill Gram-negative bacteria under conditions where the outer membrane and/or efflux pumps are disrupted. We show here that JD1 rapidly disrupts membrane potential and kills Gram-positive bacteria. Further investigation revealed that treatment with JD1 disrupts membrane barrier function and causes aberrant membranous structures to form. Additionally, exposure to JD1 reduced the number of Staphylococcus aureus and Staphylococcus epidermidis viable persister cells within broth culture by up to 1,000-fold and reduced the matrix and cell volume of biofilms that had been established for 24 h. Finally, we show that JD1 reduced the number of recoverable methicillin-resistant S. aureus organisms from infected cells. These observations indicate that JD1 inhibits staphylococcal cells in difficult-to-treat growth stages as well as, or better than, current clinical antibiotics. Thus, JD1 shows the importance of testing compounds under conditions that are relevant to infection, demonstrates the utility that membrane-targeting compounds have against multidrug-resistant bacteria, and indicates that small molecules that target bacterial cell membranes may serve as potent broad-spectrum antibacterials.
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Zhang A, Xiao Z, Liu Q, Li P, Xu F, Liu J, Tao H, Feng L, Song S, Liu Z, Huang G. CaCO 3 -Encapuslated Microspheres for Enhanced Transhepatic Arterial Embolization Treatment of Hepatocellular Carcinoma. Adv Healthc Mater 2021; 10:e2100748. [PMID: 34137207 DOI: 10.1002/adhm.202100748] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 05/21/2021] [Indexed: 12/18/2022]
Abstract
Transcatheter arterial embolization (TAE) is an extensively applied treatment method for hepatocellular carcinoma (HCC). However, the worsened tumor microenvironment (TME, e.g., reduced pH post-TAE) may result in unsatisfactory therapeutic outcome. Herein, a new kind of embolic agent, calcium carbonate encapsulated alginate microspheres (CaCO3 -ALG MSs) are synthesized. Such CaCO3 -ALG MSs are able to neutralize the tumor pH owing to the reaction of CaCO3 with protons, which would not affect the overall morphology of microspheres after decomposition of CaCO3 . TAE treatment with CaCO3 -ALG MSs is then conducted in an orthotopic rat liver cancer model. 18 F-Fluorodeoxyglucose micropositron emission tomography/computed tomography imaging is conducted post-TAE and discovered that intra-arterial injection of CaCO3 -ALG MSs shows obvious enhanced therapeutic outcome compared to the same treatment with bare ALG MSs or the clinically used lipiodol. Further studies including analysis of immune cells in tumors, cytokine assays, and bioinformatics analysis all verify the reverse of immunosuppressive TME toward a more immunosupportive one after TAE with CaCO3 -ALG MSs. The research not only presents a new CaCO3 -containing embolic agent for enhanced TAE treatment of HCC but also highlights a clinically meaningful approach to improve cancer treatment via tumor pH neutralization.
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Affiliation(s)
- Aimi Zhang
- Department of Nuclear Medicine Ren Ji Hospital School of Medicine Shanghai Jiao Tong University Shanghai 200127 China
| | - Zhisheng Xiao
- Institute of Functional Nano & Soft Materials (FUNSOM) Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University Suzhou Jiangsu 215123 China
| | - Qiufang Liu
- Department of Nuclear Medicine Fudan University Shanghai Cancer Center Shanghai 200032 China
| | - Panli Li
- Department of Nuclear Medicine Fudan University Shanghai Cancer Center Shanghai 200032 China
| | - Fei Xu
- Department of Nuclear Medicine Ren Ji Hospital School of Medicine Shanghai Jiao Tong University Shanghai 200127 China
| | - Jianjun Liu
- Department of Nuclear Medicine Ren Ji Hospital School of Medicine Shanghai Jiao Tong University Shanghai 200127 China
| | - Huiquan Tao
- Institute of Functional Nano & Soft Materials (FUNSOM) Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University Suzhou Jiangsu 215123 China
| | - Liangzhu Feng
- Institute of Functional Nano & Soft Materials (FUNSOM) Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University Suzhou Jiangsu 215123 China
| | - Shaoli Song
- Department of Nuclear Medicine Fudan University Shanghai Cancer Center Shanghai 200032 China
| | - Zhuang Liu
- Institute of Functional Nano & Soft Materials (FUNSOM) Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University Suzhou Jiangsu 215123 China
| | - Gang Huang
- Department of Nuclear Medicine Ren Ji Hospital School of Medicine Shanghai Jiao Tong University Shanghai 200127 China
- Shanghai Key Laboratory for Molecular Imaging Shanghai University of Medicine and Health Sciences Shanghai 201318 China
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12
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Olaya-Abril A, Hidalgo-Carrillo J, Luque-Almagro VM, Fuentes-Almagro C, Urbano FJ, Moreno-Vivián C, Richardson DJ, Roldán MD. Effect of pH on the denitrification proteome of the soil bacterium Paracoccus denitrificans PD1222. Sci Rep 2021; 11:17276. [PMID: 34446760 PMCID: PMC8390676 DOI: 10.1038/s41598-021-96559-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 07/23/2021] [Indexed: 11/25/2022] Open
Abstract
Denitrification is a respiratory process by which nitrate is reduced to dinitrogen. Incomplete denitrification results in the emission of the greenhouse gas nitrous oxide and this is potentiated in acidic soils, which display reduced denitrification rates and high N2O/N2 ratios compared to alkaline soils. In this work, impact of pH on the proteome of the soil denitrifying bacterium Paracoccus denitrificans PD1222 was analysed with nitrate as sole energy and nitrogen source under anaerobic conditions at pH ranging from 6.5 to 7.5. Quantitative proteomic analysis revealed that the highest difference in protein representation was observed when the proteome at pH 6.5 was compared to the reference proteome at pH 7.2. However, this difference in the extracellular pH was not enough to produce modification of intracellular pH, which was maintained at 6.5 ± 0.1. The biosynthetic pathways of several cofactors relevant for denitrification and nitrogen assimilation like cobalamin, riboflavin, molybdopterin and nicotinamide were negatively affected at pH 6.5. In addition, peptide representation of reductases involved in nitrate assimilation and denitrification were reduced at pH 6.5. Data highlight the strong negative impact of pH on NosZ synthesis and intracellular copper content, thus impairing active NosZ assembly and, in turn, leading to elevated nitrous oxide emissions.
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Affiliation(s)
- Alfonso Olaya-Abril
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Edificio Severo Ochoa, 1ª planta, Campus de Rabanales, 14071, Córdoba, Spain
| | - Jesús Hidalgo-Carrillo
- Departamento de Química Orgánica, Universidad de Córdoba, Edificio Marie Curie, Campus de Rabanales, 14071, Córdoba, Spain
| | - Víctor M Luque-Almagro
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Edificio Severo Ochoa, 1ª planta, Campus de Rabanales, 14071, Córdoba, Spain
| | - Carlos Fuentes-Almagro
- Servicio Central de Apoyo a la Investigación (SCAI), Unidad de Proteómica, Universidad de Córdoba, Campus de Rabanales, 14071, Córdoba, Spain
| | - Francisco J Urbano
- Departamento de Química Orgánica, Universidad de Córdoba, Edificio Marie Curie, Campus de Rabanales, 14071, Córdoba, Spain
| | - Conrado Moreno-Vivián
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Edificio Severo Ochoa, 1ª planta, Campus de Rabanales, 14071, Córdoba, Spain
| | - David J Richardson
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - María Dolores Roldán
- Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Edificio Severo Ochoa, 1ª planta, Campus de Rabanales, 14071, Córdoba, Spain.
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13
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Aklima J, Onojima T, Kimura S, Umiuchi K, Shibata T, Kuraoka Y, Oie Y, Suganuma Y, Ohta Y. Effects of Matrix pH on Spontaneous Transient Depolarization and Reactive Oxygen Species Production in Mitochondria. Front Cell Dev Biol 2021; 9:692776. [PMID: 34277637 PMCID: PMC8278022 DOI: 10.3389/fcell.2021.692776] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/26/2021] [Indexed: 01/28/2023] Open
Abstract
Reactive oxygen species (ROS) oxidize surrounding molecules and thus impair their functions. Since mitochondria are a major source of ROS, suppression of ROS overproduction in the mitochondria is important for cells. Spontaneous transient depolarization of individual mitochondria is a physiological phenomenon widely observed from plants to mammals. Mitochondrial uncoupling can reduce ROS production; therefore, it is conceivable that transient depolarization could reduce ROS production. However, transient depolarization has been observed with increased ROS production. Therefore, the exact contribution of transient depolarization to ROS production has not been elucidated. In this study, we examined how the spontaneous transient depolarization occurring in individual mitochondria affected ROS production. When the matrix pH increased after the addition of malate or exposure of the isolated mitochondria to a high-pH buffer, transient depolarization was stimulated. Similar stimulation by an increased matrix pH was also observed in the mitochondria in intact H9c2 cells. Modifying the mitochondrial membrane potential and matrix pH by adding K+ in the presence of valinomycin, a K+ ionophore, clarified that an increase in the matrix pH is a major cause of ROS generation. When we added ADP in the presence of oligomycin to suppress the transient depolarization without decreasing the matrix pH, we observed the suppression of mitochondrial respiration, increased matrix pH, and enhanced ROS production. Based on these results, we propose a model where spontaneous transient depolarization occurs during increased proton influx through proton channels opened by increased matrix pH, leading to the suppression of ROS production. This study improves our understanding of mitochondrial behavior.
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Affiliation(s)
- Jannatul Aklima
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan.,Department of Biochemistry and Molecular Biology, University of Chittagong, Chittagong, Bangladesh
| | - Takumi Onojima
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Sawako Kimura
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Kanji Umiuchi
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Takahiro Shibata
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yusho Kuraoka
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshiki Oie
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshiki Suganuma
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshihiro Ohta
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
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14
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Martínez-Rojas VA, Salinas-Abarca AB, Gómez-Víquez NL, Granados-Soto V, Mercado F, Murbartián J. Interaction of NHE1 and TRPA1 Activity in DRG Neurons Isolated from Adult Rats and its Role in Inflammatory Nociception. Neuroscience 2021; 465:154-165. [PMID: 33957206 DOI: 10.1016/j.neuroscience.2021.04.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/01/2021] [Accepted: 04/21/2021] [Indexed: 01/07/2023]
Abstract
Transient receptor potential ankyrin 1 (TRPA1) channel is expressed in a subset of nociceptive neurons. This channel integrates several nociceptive signals. Particularly, it is modulated by intracellular pH (pHi). Na+/H+ exchanger 1 (NHE1) contributes to the maintenance of pHi in nociceptors. However, it is currently unknown whether the interaction between TRPA1 and NHE1 contributes to the nociceptive processing. Thus, the purpose of this study was to assess the functional interaction between NHE1 and TRPA1 in small dorsal root ganglion (DRG) neurons from primary culture obtained from adult rats. Moreover, we also evaluated their possible interaction in acute and inflammatory pain. Zoniporide (selective NHE1 inhibitor) reduced pHi and increased intracellular calcium in a concentration-dependent fashion in DRG neurons. Zoniporide and allyl isothiocyanate (AITC, TRPA1 agonist) increased calcium transients in the same DRG neuron, whereas that A-967079 (TRPA1 antagonist) prevented the effect of zoniporide in DRG neurons. Repeated AITC induced TRPA1 desensitization and this effect was prevented by zoniporide. Both NHE1 and TRPA1 were localized at the membrane surface of DRG neurons in culture. Local peripheral zoniporide enhanced AITC-induced pronociception and this effect was prevented by A-967079. Likewise, zoniporide potentiated Complete Freund's Adjuvant (CFA)-induced hypersensitivity, effect which was prevented by A-967079 in vivo. CFA paw injection increased TRPA1 and decresed NHE1 protein expression in DRG. These results suggest a functional interaction between NHE1 and TRPA1 in DRG neurons in vitro. Moreover, data suggest that this interaction participates in acute and inflamatory pain conditions in vivo.
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Affiliation(s)
| | - Ana B Salinas-Abarca
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | | | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Francisco Mercado
- Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Janet Murbartián
- Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico.
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15
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A small molecule that mitigates bacterial infection disrupts Gram-negative cell membranes and is inhibited by cholesterol and neutral lipids. PLoS Pathog 2020; 16:e1009119. [PMID: 33290418 PMCID: PMC7748285 DOI: 10.1371/journal.ppat.1009119] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 12/18/2020] [Accepted: 11/01/2020] [Indexed: 01/01/2023] Open
Abstract
Infections caused by Gram-negative bacteria are difficult to fight because these pathogens exclude or expel many clinical antibiotics and host defense molecules. However, mammals have evolved a substantial immune arsenal that weakens pathogen defenses, suggesting the feasibility of developing therapies that work in concert with innate immunity to kill Gram-negative bacteria. Using chemical genetics, we recently identified a small molecule, JD1, that kills Salmonella enterica serovar Typhimurium (S. Typhimurium) residing within macrophages. JD1 is not antibacterial in standard microbiological media, but rapidly inhibits growth and curtails bacterial survival under broth conditions that compromise the outer membrane or reduce efflux pump activity. Using a combination of cellular indicators and super resolution microscopy, we found that JD1 damaged bacterial cytoplasmic membranes by increasing fluidity, disrupting barrier function, and causing the formation of membrane distortions. We quantified macrophage cell membrane integrity and mitochondrial membrane potential and found that disruption of eukaryotic cell membranes required approximately 30-fold more JD1 than was needed to kill bacteria in macrophages. Moreover, JD1 preferentially damaged liposomes with compositions similar to E. coli inner membranes versus mammalian cell membranes. Cholesterol, a component of mammalian cell membranes, was protective in the presence of neutral lipids. In mice, intraperitoneal administration of JD1 reduced tissue colonization by S. Typhimurium. These observations indicate that during infection, JD1 gains access to and disrupts the cytoplasmic membrane of Gram-negative bacteria, and that neutral lipids and cholesterol protect mammalian membranes from JD1-mediated damage. Thus, it may be possible to develop therapeutics that exploit host innate immunity to gain access to Gram-negative bacteria and then preferentially damage the bacterial cell membrane over host membranes.
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16
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Fontes FL, Peters BJ, Crans DC, Crick DC. The Acid-Base Equilibrium of Pyrazinoic Acid Drives the pH Dependence of Pyrazinamide-Induced Mycobacterium tuberculosis Growth Inhibition. ACS Infect Dis 2020; 6:3004-3014. [PMID: 33078607 DOI: 10.1021/acsinfecdis.0c00507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Pyrazinamide, a first-line antibiotic used against Mycobacterium tuberculosis, has been shown to act in a pH-dependent manner in vitro. Why pyrazinamide, an antitubercle prodrug discovered more than 65 years ago, exhibits this pH-dependent activity was unclear. Upon entering mycobacterial cells, pyrazinamide is deamidated to pyrazinoate by an enzymatic process and exists in an acid-base equilibrium with pyrazinoic acid. Thus, the effects of total pyrazinoic acid (pyrazinoic acid + pyrazinoate) on M. tuberculosis growth, pH homeostasis, and proton motive force over a range of pH values found in host tissues were investigated. Although M. tuberculosis was able to maintain pH homeostasis over an external pH range of 7.0 to 5.5, total pyrazinoic acid induced growth inhibition increased as culture medium pH was decreased from 7.3 to 6.4. Consistent with growth inhibition, total pyrazinoic acid increased both acidification of the bacterial cytoplasm and dissipation of membrane potential as the environmental pH decreased when added to the bacterial suspensions. The results suggest pyrazinoic acid is the active form of the drug, which acts as an uncoupler of proton motive force, likely a protonophore, providing a mechanistic explanation for the pH dependence of the drug activity.
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Affiliation(s)
- Fabio L. Fontes
- Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, United States
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Benjamin J. Peters
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Debbie C. Crans
- Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, United States
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Dean C. Crick
- Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, United States
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523, United States
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17
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Yang Q, Cristea A, Roberts C, Liu K, Song Y, Xiao H, Shi H, Ma Y. Unveil early-stage nanocytotoxicity by a label-free single cell pH nanoprobe. Analyst 2020; 145:7210-7224. [PMID: 32960188 PMCID: PMC7655686 DOI: 10.1039/d0an01437k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Single-cell analysis is an emerging research area that aims to reveal delicate cellular status and underlying mechanisms by conquering the intercellular heterogeneity. Current single-cell research methods, however, are highly dependent on cell-destructive protocols and cannot sequentially display the progress of cellular events. A recently developed pH nanoprobe in our lab conceptually showed its ability to detect intracellular pH (pHi) without cell labeling or disruption. In the present study, we took the cytotoxicity of nanoparticles (NPs) as a typical example of cell heterogeneity, to testify the practicality of the pH nanoprobe in interpreting cell status. Three types of NPs (CeO2, TiO2, and SiO2) were employed to generate varied toxic effects. Results showed that the traditional assays - including cell viability, intracellular ROS generation, and mitochondrial inner membrane depolarization - not only failed to report the nanotoxicity accurately and timely, but also drew confusing or misleading conclusions. The pH nanoprobe revealed explicit pHi changes induced by the NPs, which corresponded well with the cell damages found by the transmission electron microscopic (TEM) imaging. Besides, our results unveiled an unexpectedly devastating effect of SiO2 NPs on cells during the early stage NP-cell interaction. The developed novel pH nanoprobe demonstrated a rapid sensing capability at single-cell resolution with minimum invasiveness. Therefore, it may become a promising alternative for a wide range of applications in areas such as single-cell research and precision medicine.
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Affiliation(s)
- Qingbo Yang
- Department of Chemistry, and Center for Biomedical Research, Missouri University of Science and Technology, Rolla, MO 65409, USA.
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18
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Wilson LT, Tipping WJ, Jamieson LE, Wetherill C, Henley Z, Faulds K, Graham D, Mackay SP, Tomkinson NCO. A new class of ratiometric small molecule intracellular pH sensors for Raman microscopy. Analyst 2020; 145:5289-5298. [PMID: 32672252 DOI: 10.1039/d0an00865f] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intracellular pH (pHi) homeostasis is intertwined with a myriad of normal cellular behaviors as well as pathological processes. As such, small molecule probes for the measurement of pHi are invaluable tools for chemical biology, facilitating the study of the role of pH in cellular function and disease. The field of small molecule pHi sensors has traditionally been dominated with probes based on fluorescent scaffolds. In this study, a series of low molecular weight (<260) oligoyne compounds have been developed which exhibit pH sensitive alkyne stretching frequencies (νalkyne) in Raman spectroscopy. The modular design of the compounds enabled tuneability of their pKa(H) through simple structural modification, such that continuous pH sensitivity is achieved over the range 2-10. Alkyne stretching bands reside in the 'cell-silent' region of the Raman spectrum (1800-2600 cm-1) and are readily detectable in a cellular environment with subcellular spatial resolution. This enabled the application of a pH sensitive oligoyne compound to the ratiometric sensing of pHi in prostate cancer (PC3) cells in response to drug treatment. We propose that probes based on Alkyne Tag Raman Imaging offer an entirely new platform for the sensing of pHi, complementary to fluorescence microscopy.
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Affiliation(s)
- Liam T Wilson
- Department of Pure and Applied Chemistry, WestCHEM, Thomas Graham Building, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
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19
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Yew HM, Zimmer AM, Perry SF. Assessing intracellular pH regulation in H +-ATPase-rich ionocytes in zebrafish larvae using in vivo ratiometric imaging. J Exp Biol 2020; 223:jeb212928. [PMID: 32029462 DOI: 10.1242/jeb.212928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 01/28/2020] [Indexed: 12/11/2022]
Abstract
The H+-ATPase-rich (HR) cells of zebrafish larvae are a sub-type of ion-transporting cell located on the yolk sac epithelium that are responsible for Na+ uptake and H+ extrusion. Current models of HR cell ion transport mechanisms in zebrafish larvae are well established, but little is known about the involvement of the various ion transport pathways in regulating intracellular acid-base status. Here, a ratiometric imaging technique was developed and validated to monitor intracellular pH (pHi) continuously in larval zebrafish HR cells in vivo Gene knockdown or CRISPR/Cas9 knockout approaches were used to evaluate the roles of the two principal apical membrane acid excretory pathways, the Na+/H+ exchanger (NHE3b; slc9a3.2) and the H+-ATPase (atpv1aa). Additionally, the role of HR cell cytosolic carbonic anhydrase (CAc) was investigated because of its presumed role in providing H+ for Na+/H+ exchange and H+-ATPase. The temporal pattern and extent of intracellular acidification during exposure of fish to 1% CO2 and the extent of post-CO2 alkalisation were altered markedly in fish experiencing knockdown/knockout of CAc, NHE3b or H+-ATPase. Although there were slight differences among the three knockdown/knockout experiments, the typical response was a greater degree of intracellular acidification during CO2 exposure and a reduced capacity to restore pHi to baseline levels post-hypercapnia. The metabolic alkalosis and subsequent acidification associated with 20 mmol l-1 NH4Cl exposure and its washout were largely unaffected by gene knockdown. Overall, the results suggest markedly different mechanisms of intracellular acid-base regulation in zebrafish HR cells depending on the nature of the acid-base disturbance.
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Affiliation(s)
- H M Yew
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON KIN 6N5, Canada
| | - A M Zimmer
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON KIN 6N5, Canada
| | - S F Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ON KIN 6N5, Canada
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20
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Aranda-Díaz A, Obadia B, Dodge R, Thomsen T, Hallberg ZF, Güvener ZT, Ludington WB, Huang KC. Bacterial interspecies interactions modulate pH-mediated antibiotic tolerance. eLife 2020; 9:51493. [PMID: 31995029 PMCID: PMC7025823 DOI: 10.7554/elife.51493] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 01/28/2020] [Indexed: 12/11/2022] Open
Abstract
Predicting antibiotic efficacy within microbial communities remains highly challenging. Interspecies interactions can impact antibiotic activity through many mechanisms, including alterations to bacterial physiology. Here, we studied synthetic communities constructed from the core members of the fruit fly gut microbiota. Co-culturing of Lactobacillus plantarum with Acetobacter species altered its tolerance to the transcriptional inhibitor rifampin. By measuring key metabolites and environmental pH, we determined that Acetobacter species counter the acidification driven by L. plantarum production of lactate. Shifts in pH were sufficient to modulate L. plantarum tolerance to rifampin and the translational inhibitor erythromycin. A reduction in lag time exiting stationary phase was linked to L. plantarum tolerance to rifampicin, opposite to a previously identified mode of tolerance to ampicillin in E. coli. This mechanistic understanding of the coupling among interspecies interactions, environmental pH, and antibiotic tolerance enables future predictions of growth and the effects of antibiotics in more complex communities.
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Affiliation(s)
- Andrés Aranda-Díaz
- Department of Bioengineering, Stanford University, Stanford, United States
| | - Benjamin Obadia
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Ren Dodge
- Department of Embryology, Carnegie Institution of Washington, Baltimore, United States
| | - Tani Thomsen
- Department of Bioengineering, Stanford University, Stanford, United States
| | - Zachary F Hallberg
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States
| | - Zehra Tüzün Güvener
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - William B Ludington
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Department of Embryology, Carnegie Institution of Washington, Baltimore, United States
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, United States.,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, United States.,Chan Zuckerberg Biohub, San Francisco, United States
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21
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Luo E, Wang D, Yan G, Qiao Y, Zhu B, Liu B, Hou J, Tang C. The NF-κB/miR-425-5p/MCT4 axis: A novel insight into diabetes-induced endothelial dysfunction. Mol Cell Endocrinol 2020; 500:110641. [PMID: 31711985 DOI: 10.1016/j.mce.2019.110641] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/05/2019] [Accepted: 11/06/2019] [Indexed: 12/21/2022]
Abstract
Endothelial cells (ECs) primarily rely on glycolysis for their energy metabolism, and the final product of glycolysis-lactate-is transferred out of cells via monocarboxylate transporter 4 (MCT4). We previously showed that MCT4 downregulation is involved in diabetic endothelial injury. However, the underlying regulatory mechanisms of MCT4 in diabetes remain unclear. This study showed that miR-425-5p was significantly upregulated in diabetic patients and human umbilical vein endothelial cells (HUVECs) treated with high glucose (HG) and interleukin-1β (IL-1β). MCT4 was shown to be a direct target gene of miR-425-5p, and miR-425-5p expression led to MCT4 downregulation, lactate accumulation and increased apoptosis in HUVECs. Furthermore, the results indicated that NF-κB signaling activation increased miR-425-5p levels and induced MCT4 downregulation, lactate accumulation and apoptosis in HUVECs. In conclusion, NF-κB/miR-425-5p/MCT4 axis activation plays a crucial role in the EC injury induced by HG and IL-1β.
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Affiliation(s)
- Erfei Luo
- School of Medicine, Southeast University, Nanjing, 210009, China.
| | - Dong Wang
- Department of Cardiology, Zhongda Hospital, Southeast University, Nanjing, 210009, China.
| | - Gaoliang Yan
- Department of Cardiology, Zhongda Hospital, Southeast University, Nanjing, 210009, China.
| | - Yong Qiao
- Department of Cardiology, Zhongda Hospital, Southeast University, Nanjing, 210009, China.
| | - Boqian Zhu
- School of Medicine, Southeast University, Nanjing, 210009, China.
| | - Bo Liu
- School of Medicine, Southeast University, Nanjing, 210009, China.
| | - Jiantong Hou
- School of Medicine, Southeast University, Nanjing, 210009, China.
| | - Chengchun Tang
- Department of Cardiology, Zhongda Hospital, Southeast University, Nanjing, 210009, China.
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22
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Cagnac O, Baghour M, Jaime‐Pérez N, Aranda‐Sicilia MN, Sánchez‐Romero ME, Rodríguez‐Rosales MP, Venema K. Deletion of the N‐terminal domain of the yeast vacuolar (Na
+
,K
+
)/H
+
antiporter Vnx1p improves salt tolerance in yeast and transgenic
Arabidopsis. Yeast 2020; 37:173-185. [DOI: 10.1002/yea.3450] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 11/11/2019] [Accepted: 11/22/2019] [Indexed: 12/29/2022] Open
Affiliation(s)
| | - Mourad Baghour
- Faculté Pluridisciplinaire de Nador Université Mohammed Premier Nador Morocco
| | | | | | | | | | - Kees Venema
- Estación Experimental del Zaidín CSIC Granada Spain
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23
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Chen Z, Chen L, Chen K, Lin H, Shen M, Chen L, Zhu H, Zhu Y, Wang Q, Xi F, Huang X, Wang Y, Liao W, Bin J, Asakura M, Liu J, Kitakaze M, Liao Y. Overexpression of Na +-HCO 3- cotransporter contributes to the exacerbation of cardiac remodeling in mice with myocardial infarction by increasing intracellular calcium overload. Biochim Biophys Acta Mol Basis Dis 2019; 1866:165623. [PMID: 31778748 DOI: 10.1016/j.bbadis.2019.165623] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 10/25/2019] [Accepted: 11/22/2019] [Indexed: 12/31/2022]
Abstract
The role of the cardiac isoform of the electrogenic sodium-bicarbonate ion cotransporter (NBCe1) in cardiac remodeling is not fully understood. The aim of this study was to assess the effects of NBCe1 overexpression on cardiac remodeling induced by myocardial infarction (MI) in mice. We generated NBCe1 transgenic (Tg) mice and NBCe1 overexpressing adult mouse ventricular myocytes (AMVMs) to investigate the role of NBCe1 on post-MI remodeling and calcium kinetics. Tg mice showed a markedly higher mortality rate and larger infarct size after MI. At 6 weeks after MI, the maximum rising rates of left ventricular pressure (dp/dt), contractility index, and the exponential time constant of relaxation (τ) were markedly lower, and there was higher cardiomyocyte apoptosis, in Tg mice compared with WT mice. In cultured AMVMs, overexpression of NBCe1 decreased sarcomere shortening and calcium amplitude. In WT AMVMs, the rates of the rise and decay phase of calcium transients, indicated by the rising time (Tpeak, time to peak) and decay time constant (τd), and the number of apoptotic cells, were increased following hypoxia, while overexpression of NBCe1 further increased Tpeak and cellular apoptosis, but not τd. Intracellular resting calcium and sodium concentrations were significantly increased following both hypoxia and NBCe1 overexpression. Co-treatment with S0859, an NBCe1 antagonist, blocked the hypoxia-induced increase in Tpeak, τd, intracellular resting calcium and sodium concentrations, and apoptosis in cardiomyocytes. These findings indicate that NBCe1 overexpression promotes cardiac remodeling by increasing intracellular calcium overload. Therefore, NBCe1 should be a potential target for treatment of cardiac remodeling.
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Affiliation(s)
- Zhenhuan Chen
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Department of Cardiology, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi, 330006, China
| | - Lu Chen
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Kaitong Chen
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Hairuo Lin
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Mengjia Shen
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Lin Chen
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Hailin Zhu
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yingqi Zhu
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Qiancheng Wang
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Fang Xi
- Department of Military Preventive Medicine, Frontier Medical Training Brigade, Army Medical University, Hutubi, Xinjiang 831200, China
| | - Xiaobo Huang
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yuegang Wang
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Wangjun Liao
- Department of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jianping Bin
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Masanori Asakura
- Cardiovascular Division of the Department of Medicine, National Cerebral and Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
| | - Jie Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen 518060, China
| | - Masafumi Kitakaze
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Cardiovascular Division of the Department of Medicine, National Cerebral and Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan.
| | - Yulin Liao
- Department of Cardiology, State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
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Sikkema HR, Gaastra BF, Pols T, Poolman B. Cell Fuelling and Metabolic Energy Conservation in Synthetic Cells. Chembiochem 2019; 20:2581-2592. [PMID: 31381223 DOI: 10.1002/cbic.201900398] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Indexed: 12/14/2022]
Abstract
We are aiming for a blue print for synthesizing (moderately complex) subcellular systems from molecular components and ultimately for constructing life. However, without comprehensive instructions and design principles, we rely on simple reaction routes to operate the essential functions of life. The first forms of synthetic life will not make every building block for polymers de novo according to complex pathways, rather they will be fed with amino acids, fatty acids and nucleotides. Controlled energy supply is crucial for any synthetic cell, no matter how complex. Herein, we describe the simplest pathways for the efficient generation of ATP and electrochemical ion gradients. We have estimated the demand for ATP by polymer synthesis and maintenance processes in small cell-like systems, and we describe circuits to control the need for ATP. We also present fluorescence-based sensors for pH, ionic strength, excluded volume, ATP/ADP, and viscosity, which allow the major physicochemical conditions inside cells to be monitored and tuned.
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Affiliation(s)
- Hendrik R Sikkema
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Bauke F Gaastra
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Tjeerd Pols
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Bert Poolman
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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Ruhr IM, McCourty H, Bajjig A, Crossley DA, Shiels HA, Galli GLJ. Developmental plasticity of cardiac anoxia-tolerance in juvenile common snapping turtles ( Chelydra serpentina). Proc Biol Sci 2019; 286:20191072. [PMID: 31238852 PMCID: PMC6599983 DOI: 10.1098/rspb.2019.1072] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
For some species of ectothermic vertebrates, early exposure to hypoxia during embryonic development improves hypoxia-tolerance later in life. However, the cellular mechanisms underlying this phenomenon are largely unknown. Given that hypoxic survival is critically dependent on the maintenance of cardiac function, we tested the hypothesis that developmental hypoxia alters cardiomyocyte physiology in a manner that protects the heart from hypoxic stress. To test this hypothesis, we studied the common snapping turtle, which routinely experiences chronic developmental hypoxia and exploits hypoxic environments in adulthood. We isolated cardiomyocytes from juvenile turtles that embryonically developed in either normoxia (21% O2) or hypoxia (10% O2), and subjected them to simulated anoxia and reoxygenation, while simultaneously measuring intracellular Ca2+, pH and reactive oxygen species (ROS) production. Our results suggest developmental hypoxia improves cardiomyocyte anoxia-tolerance of juvenile turtles, which is supported by enhanced myofilament Ca2+-sensitivity and a superior ability to suppress ROS production. Maintenance of low ROS levels during anoxia might limit oxidative damage and a greater sensitivity to Ca2+ could provide a mechanism to maintain contractile force. Our study suggests developmental hypoxia has long-lasting effects on turtle cardiomyocyte function, which might prime their physiology for exploiting hypoxic environments.
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Affiliation(s)
- Ilan M Ruhr
- 1 Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester , Manchester M13 9NT , UK
| | - Heather McCourty
- 1 Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester , Manchester M13 9NT , UK
| | - Afaf Bajjig
- 1 Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester , Manchester M13 9NT , UK
| | - Dane A Crossley
- 2 Department of Biological Sciences, University of North Texas , Denton, TX 76203 , USA
| | - Holly A Shiels
- 1 Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester , Manchester M13 9NT , UK
| | - Gina L J Galli
- 1 Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester , Manchester M13 9NT , UK
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26
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A protonic biotransducer controlling mitochondrial ATP synthesis. Sci Rep 2018; 8:10423. [PMID: 30002478 PMCID: PMC6043558 DOI: 10.1038/s41598-018-28435-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 06/20/2018] [Indexed: 12/14/2022] Open
Abstract
In nature, protons (H+) play an important role in biological activities such as in mitochondrial ATP synthesis, which is driven by a H+ gradient across the inner membrane, or in the activation of acid sensing ion channels in neuron cells. Bioprotonic devices directly interface with the H+ concentration (pH) to facilitate engineered interactions with these biochemical processes. Here we develop a H+ biotransducer that changes the pH in a mitochondrial matrix by controlling the flow of H+ between a conductive polymer of sulfonated polyaniline and solution. We have successfully modulated the rate of ATP synthesis in mitochondria by altering the solution pH. Our H+ biotransducer provides a new way to monitor and modulate pH dependent biological functions at the interface between the electronic devices and biological materials.
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Su PH, Lai YH. A Reliable and Non-destructive Method for Monitoring the Stromal pH in Isolated Chloroplasts Using a Fluorescent pH Probe. FRONTIERS IN PLANT SCIENCE 2017; 8:2079. [PMID: 29259618 PMCID: PMC5723387 DOI: 10.3389/fpls.2017.02079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/21/2017] [Indexed: 05/08/2023]
Abstract
The proton gradient established by the pH difference across a biological membrane is essential for many physiological processes, including ATP synthesis and ion and metabolite transport. Currently, ionophores are used to study proton gradients, and determine their importance to biological functions of interest. Because of the lack of an easy method for monitoring the proton gradient across the inner envelope membrane of chloroplasts (ΔpHenv), whether the concentration of ionophores used can effectively abolish the ΔpHenv is not proven for most experiments. To overcome this hindrance, we tried to setup an easy method for real-time monitoring of the stromal pH in buffered, isolated chloroplasts by using fluorescent pH probes; using this method the ΔpHenv can be calculated by subtracting the buffer pH from the measured stromal pH. When three fluorescent dyes, BCECF-AM [2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester], CFDA-SE [5(6)-Carboxyfluorescein diacetate succinimidyl ester] and SNARF-1 carboxylic acid acetate succinimidyl ester were incubated with isolated chloroplasts, BCECF-AM and CFDA-SE, but not the ester-formed SNARF-1 were taken up by chloroplasts and digested with esterase to release high levels of fluorescence. According to its relatively higher pKa value (6.98, near the physiological pH of the stroma), BCECF was chosen for further development. Due to shielding of the excitation and emission lights by chloroplast pigments, the ratiometric fluorescence of BCECF was highly dependent on the concentration of chloroplasts. By using a fixed concentration of chloroplasts, a highly correlated standard curve of pH to the BCECF ratiometric fluorescence with an r-square value of 0.98 was obtained, indicating the reliability of this method. Consistent with previous reports, the light-dependent formation of ΔpHenv can be detected ranging from 0.15 to 0.33 pH units upon illumination. The concentration of the ionophore nigericin required to collapse the ΔpHenv was then studied. The establishment of a non-destructive method of monitoring the stromal pH will be valuable for studying the roles of the ΔpHenv in chloroplast physiology.
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Affiliation(s)
- Pai-Hsiang Su
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan, Taiwan
- *Correspondence: Pai-Hsiang Su,
| | - Yen-Hsun Lai
- Biotechnology Center in Southern Taiwan, Academia Sinica, Tainan, Taiwan
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Wang C, Wang Y, Li Y, Bodemann B, Zhao T, Ma X, Huang G, Hu Z, DeBerardinis RJ, White MA, Gao J. A nanobuffer reporter library for fine-scale imaging and perturbation of endocytic organelles. Nat Commun 2015; 6:8524. [PMID: 26437053 PMCID: PMC4600749 DOI: 10.1038/ncomms9524] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 09/01/2015] [Indexed: 02/07/2023] Open
Abstract
Endosomes, lysosomes and related catabolic organelles are a dynamic continuum of vacuolar structures that impact a number of cell physiological processes such as protein/lipid metabolism, nutrient sensing and cell survival. Here we develop a library of ultra-pH-sensitive fluorescent nanoparticles with chemical properties that allow fine-scale, multiplexed, spatio-temporal perturbation and quantification of catabolic organelle maturation at single organelle resolution to support quantitative investigation of these processes in living cells. Deployment in cells allows quantification of the proton accumulation rate in endosomes; illumination of previously unrecognized regulatory mechanisms coupling pH transitions to endosomal coat protein exchange; discovery of distinct pH thresholds required for mTORC1 activation by free amino acids versus proteins; broad-scale characterization of the consequence of endosomal pH transitions on cellular metabolomic profiles; and functionalization of a context-specific metabolic vulnerability in lung cancer cells. Together, these biological applications indicate the robustness and adaptability of this nanotechnology-enabled 'detection and perturbation' strategy.
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Affiliation(s)
- Chensu Wang
- Department of Pharmacology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Yiguang Wang
- Department of Pharmacology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Yang Li
- Department of Pharmacology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Brian Bodemann
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Tian Zhao
- Department of Pharmacology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Xinpeng Ma
- Department of Pharmacology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Gang Huang
- Department of Pharmacology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Zeping Hu
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Ralph J. DeBerardinis
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Michael A. White
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
| | - Jinming Gao
- Department of Pharmacology, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA
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High glucose and interleukin 1β-induced apoptosis in human umbilical vein endothelial cells involves in down-regulation of monocarboxylate transporter 4. Biochem Biophys Res Commun 2015; 466:607-14. [DOI: 10.1016/j.bbrc.2015.09.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 09/04/2015] [Indexed: 12/28/2022]
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pH manipulation as a novel strategy for treating mucormycosis. Antimicrob Agents Chemother 2015; 59:6968-74. [PMID: 26324263 PMCID: PMC4604374 DOI: 10.1128/aac.01366-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 08/22/2015] [Indexed: 12/18/2022] Open
Abstract
Mucormycosis is a fatal fungal disease caused by several organisms within the order Mucorales. In recent years, traumatic injury has emerged as a novel risk factor for mucormycosis. Current antifungal therapy is ineffective, expensive, and typically requires extensive surgical debridement. There is thus a pressing need for safe prophylactic treatment that can be rapidly and easily applied to high-risk patients, such as those with major trauma injuries. Acetic acid has been used as a topical treatment for burn wounds for centuries and has proven activity against Gram-negative bacteria. Here, we demonstrate that acetic acid is also highly effective against major pathogenic groups of Mucorales, even at very low concentrations (0.3%). This antifungal effect is not seen with other acids, such as hydrochloric and lactic acid, suggesting that acetic acid activity against Mucorales spores is not solely evoked by low environmental pH. In agreement with this, we demonstrate that the antifungal activity of acetic acid arises from a combination of its ability to potently lower intracellular pH and from pH-independent toxicity. Thus, dilute acetic acid may offer a low-cost, safe, prophylactic treatment for patients at risk of invasive mucormycosis following traumatic injury.
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Buelli S, Perico L, Galbusera M, Abbate M, Morigi M, Novelli R, Gagliardini E, Tentori C, Rottoli D, Sabadini E, Saito T, Kawano M, Saeki T, Zoja C, Remuzzi G, Benigni A. Mitochondrial-dependent Autoimmunity in Membranous Nephropathy of IgG4-related Disease. EBioMedicine 2015; 2:456-66. [PMID: 26137589 PMCID: PMC4485911 DOI: 10.1016/j.ebiom.2015.03.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 03/04/2015] [Accepted: 03/05/2015] [Indexed: 01/13/2023] Open
Abstract
The pathophysiology of glomerular lesions of membranous nephropathy (MN), including seldom-reported IgG4-related disease, is still elusive. Unlike in idiopathic MN where IgG4 prevails, in this patient IgG3 was predominant in glomerular deposits in the absence of circulating anti-phospholipase A2 receptor antibodies, suggesting a distinct pathologic process. Here we documented that IgG4 retrieved from the serum of our propositus reacted against carbonic anhydrase II (CAII) at the podocyte surface. In patient's biopsy, glomerular CAII staining increased and co-localized with subepithelial IgG4 deposits along the capillary walls. Patient's IgG4 caused a drop in cell pH followed by mitochondrial dysfunction, excessive ROS production and cytoskeletal reorganization in cultured podocytes. These events promoted mitochondrial superoxide-dismutase-2 (SOD2) externalization on the plasma membrane, becoming recognizable by complement-binding IgG3 anti-SOD2. Among patients with IgG4-related disease only sera of those with IgG4 anti-CAII antibodies caused low intracellular pH and mitochondrial alterations underlying SOD2 externalization. Circulating IgG4 anti-CAII can cause podocyte injury through processes of intracellular acidification, mitochondrial oxidative stress and neoantigen induction in patients with IgG4 related disease. The onset of MN in a subset of patients could be due to IgG4 antibodies recognizing CAII with consequent exposure of mitochondrial neoantigen in the context of multifactorial pathogenesis of disease. In a patient with IgG4-related disease, glomerular CAII increases and colocalizes with IgG4 deposits. IgG4 from patient's serum reacts against CAII expressed by podocytes. IgG4 causes acidification, mitochondrial dysfunction and ROS-dependent cytoskeletal alterations in cultured podocytes. IgG4 induces the externalization on the plasma membrane of clustered SOD2, becoming recognizable by complement-binding IgG3.
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Affiliation(s)
- Simona Buelli
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Luca Perico
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Miriam Galbusera
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Mauro Abbate
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Marina Morigi
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Rubina Novelli
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Elena Gagliardini
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Chiara Tentori
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Daniela Rottoli
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Ettore Sabadini
- Unit of Nephrology and Dialysis, Azienda Ospedaliera Papa Giovanni XXIII, Bergamo, Italy
| | - Takao Saito
- General Medical Research Center, Faculty of Medicine, Fukuoka University, Japan
| | - Mitsuhiro Kawano
- Department of Rheumatology, University School of Medicine, Kanazawa, Japan
| | - Takako Saeki
- Department of Internal Medicine, Red Cross Hospital, Nagaoka, Japan
| | - Carlamaria Zoja
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Giuseppe Remuzzi
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy ; Unit of Nephrology and Dialysis, Azienda Ospedaliera Papa Giovanni XXIII, Bergamo, Italy
| | - Ariela Benigni
- IRCCS - Istituto di Ricerche Farmacologiche "Mario Negri", Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
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Chernet BT, Levin M. Transmembrane voltage potential of somatic cells controls oncogene-mediated tumorigenesis at long-range. Oncotarget 2015; 5:3287-306. [PMID: 24830454 PMCID: PMC4102810 DOI: 10.18632/oncotarget.1935] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The microenvironment is increasingly recognized as a crucial aspect of cancer. In contrast and complement to the field's focus on biochemical factors and extracellular matrix, we characterize a novel aspect of host:tumor interaction - endogenous bioelectric signals among non-excitable somatic cells. Extending prior work focused on the bioelectric state of cancer cells themselves, we show for the first time that the resting potentials of distant cells are critical for oncogene-dependent tumorigenesis. In the Xenopus laevis tadpole model, we used human oncogenes such as mutant KRAS to drive formation of tumor-like structures that exhibited overproliferation, increased nuclear size, hypoxia, acidity, and leukocyte attraction. Remarkably, misexpression of hyperpolarizing ion channels at distant sites within the tadpole significantly reduced the incidence of these tumors. The suppression of tumorigenesis could also be achieved by hyperpolarization using native CLIC1 chloride channels, suggesting a treatment modality not requiring gene therapy. Using a dominant negative approach, we implicate HDAC1 as the mechanism by which resting potential changes affect downstream cell behaviors. Based on published data on the voltage-mediated changes of butyrate flux through the SLC5A8 transporter, we present a model linking resting potentials of host cells to the ability of oncogenes to initiate tumorigenesis. Antibiotic data suggest that the relevant butyrate is generated by a native bacterial species, identifying a novel link between the microbiome and cancer that is mediated by alterations in bioelectric signaling.
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Affiliation(s)
- Brook T Chernet
- Center for Regenerative and Developmental Biology and Department of Biology Tufts University 200 Boston Avenue,Suite 4600 Medford, MA 02155 U.S.A
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33
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Fluorescence imaging of intracellular Ca2+, Na+, and H+ in cultured microglia. Methods Mol Biol 2013. [PMID: 23813378 DOI: 10.1007/978-1-62703-520-0_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The behavior of microglial cells involves the activity of a variety of ion channels and ion transporters, which are implicated in the regulation of ion concentrations, membrane potential, and cell volume of microglia. Fluorescence imaging has been proven to be an elegant method to study ion concentration changes in intact microglial cells under physiological and pathophysiological conditions. The development of highly specific ion indicators has made it possible to detect changes in intracellular Ca(2+), Na(+), and H(+) concentrations of microglial cells as a result of ion channel or ion transporter activity. Fluorescence signals of isolated dye-loaded microglial cells can be detected via a CCD camera equipped to a conventional microscope. This chapter summarizes protocols of loading of microglial cells with small-molecule ion indicators as well as protocols optimal for measurement and analysis of intracellular Ca(2+), Na(+), and H(+) concentrations in microglia in vitro.
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Kathagen N, Prehm P. Regulation of intracellular pH by glycosaminoglycans. J Cell Physiol 2013; 228:2071-5. [DOI: 10.1002/jcp.24376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 03/25/2013] [Indexed: 01/17/2023]
Affiliation(s)
- Nadine Kathagen
- Institute of Physiological Chemistry and Pathobiochemistry, Muenster University, Hospital; Münster; Germany
| | - Peter Prehm
- Institute of Physiological Chemistry and Pathobiochemistry, Muenster University, Hospital; Münster; Germany
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Qiu J, Tsien C, Thapalaya S, Narayanan A, Weihl CC, Ching JK, Eghtesad B, Singh K, Fu X, Dubyak G, McDonald C, Almasan A, Hazen SL, Naga Prasad SV, Dasarathy S. Hyperammonemia-mediated autophagy in skeletal muscle contributes to sarcopenia of cirrhosis. Am J Physiol Endocrinol Metab 2012; 303:E983-93. [PMID: 22895779 PMCID: PMC3469607 DOI: 10.1152/ajpendo.00183.2012] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hyperammonemia and sarcopenia (loss of skeletal muscle) are consistent abnormalities in cirrhosis and portosystemic shunting. We have shown that muscle ubiquitin-proteasome components are not increased with hyperammonemia despite sarcopenia. This suggests that an alternative mechanism of proteolysis contributes to sarcopenia in cirrhosis. We hypothesized that autophagy could be this alternative pathway since we observed increases in classic autophagy markers, increased LC3 lipidation, beclin-1 expression, and p62 degradation in immunoblots of skeletal muscle protein in cirrhotic patients. We observed similar changes in these autophagy markers in the portacaval anastamosis (PCA) rat model. To determine the mechanistic relationship between hyperammonemia and autophagy, we exposed murine C(2)C(12) myotubes to ammonium acetate. Significant increases in LC3 lipidation, beclin-1 expression, and p62 degradation occurred by 1 h, whereas autophagy gene expression (LC3, Atg5, Atg7, beclin-1) increased at 24 h. C(2)C(12) cells stably expressing GFP-LC3 or GFP-mCherry-LC3 constructs showed increased formation of mature autophagosomes supported by electron microscopic studies. Hyperammonemia also increased autophagic flux in mice, as quantified by an in vivo autophagometer. Because hyperammonemia induces nitration of proteins in astrocytes, we quantified global muscle protein nitration in cirrhotic patients, in the PCA rat, and in C(2)C(12) cells treated with ammonium acetate. Increased protein nitration was observed in all of these systems. Furthermore, colocalization of nitrated proteins with GFP-LC3-positive puncta in hyperammonemic C(2)C(12) cells suggested that autophagy is involved in degradation of nitrated proteins. These observations show that increased skeletal muscle autophagy in cirrhosis is mediated by hyperammonemia and may contribute to sarcopenia of cirrhosis.
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Affiliation(s)
- Jia Qiu
- Departments of Pathobiology, Cleveland Clinic, Cleveland, Ohio 44195, USA
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Goodson SG, Qiu Y, Sutton KA, Xie G, Jia W, O'Brien DA. Metabolic substrates exhibit differential effects on functional parameters of mouse sperm capacitation. Biol Reprod 2012; 87:75. [PMID: 22837480 DOI: 10.1095/biolreprod.112.102673] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Although substantial evidence exists that sperm ATP production via glycolysis is required for mammalian sperm function and male fertility, conflicting reports involving multiple species have appeared regarding the ability of individual glycolytic or mitochondrial substrates to support the physiological changes that occur during capacitation. Several mouse models with defects in the signaling pathways required for capacitation exhibit reductions in sperm ATP levels, suggesting regulatory interactions between sperm metabolism and signal transduction cascades. To better understand these interactions, we conducted quantitative studies of mouse sperm throughout a 2-h in vitro capacitation period and compared the effects of single substrates assayed under identical conditions. Multiple glycolytic and nonglycolytic substrates maintained sperm ATP levels and comparable percentages of motility, but only glucose and mannose supported hyperactivation. These monosaccharides and fructose supported the full pattern of tyrosine phosphorylation, whereas nonglycolytic substrates supported at least partial tyrosine phosphorylation. Inhibition of glycolysis impaired motility in the presence of glucose, fructose, or pyruvate but not in the presence of hydroxybutyrate. Addition of an uncoupler of oxidative phosphorylation reduced motility with pyruvate or hydroxybutyrate as substrates but unexpectedly stimulated hyperactivation with fructose. Investigating differences between glucose and fructose in more detail, we demonstrated that hyperactivation results from the active metabolism of glucose. Differences between glucose and fructose appeared to be downstream of changes in intracellular pH, which rose to comparable levels during incubation with either substrate. Sperm redox pathways were differentially affected, with higher levels of associated metabolites and reactive oxygen species generated during incubations with fructose than during incubations with glucose.
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Affiliation(s)
- Summer G Goodson
- Laboratories for Reproductive Biology, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA
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Jenkins EC, Debnath S, Gundry S, Gundry S, Uyar U, Fata JE. Intracellular pH regulation by Na+/H+ exchanger-1 (NHE1) is required for growth factor-induced mammary branching morphogenesis. Dev Biol 2012; 365:71-81. [DOI: 10.1016/j.ydbio.2012.02.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 01/30/2012] [Accepted: 02/09/2012] [Indexed: 01/19/2023]
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38
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Mancarella S, Wang Y, Deng X, Landesberg G, Scalia R, Panettieri RA, Mallilankaraman K, Tang XD, Madesh M, Gill DL. Hypoxia-induced acidosis uncouples the STIM-Orai calcium signaling complex. J Biol Chem 2011; 286:44788-98. [PMID: 22084246 PMCID: PMC3247972 DOI: 10.1074/jbc.m111.303081] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 11/11/2011] [Indexed: 12/18/2022] Open
Abstract
The endoplasmic reticulum Ca(2+)-sensing STIM proteins mediate Ca(2+) entry signals by coupling to activate plasma membrane Orai channels. We reveal that STIM-Orai coupling is rapidly blocked by hypoxia and the ensuing decrease in cytosolic pH. In smooth muscle cells or HEK293 cells coexpressing STIM1 and Orai1, acute hypoxic conditions rapidly blocked store-operated Ca(2+) entry and the Orai1-mediated Ca(2+) release-activated Ca(2+) current (I(CRAC)). Hypoxia-induced blockade of Ca(2+) entry and I(CRAC) was reversed by NH(4)(+)-induced cytosolic alkalinization. Hypoxia and acidification both blocked I(CRAC) induced by the short STIM1 Orai-activating region. Although hypoxia induced STIM1 translocation into junctions, it did not dissociate the STIM1-Orai1 complex. However, both hypoxia and cytosolic acidosis rapidly decreased Förster resonance energy transfer (FRET) between STIM1-YFP and Orai1-CFP. Thus, although hypoxia promotes STIM1 junctional accumulation, the ensuing acidification functionally uncouples the STIM1-Orai1 complex providing an important mechanism protecting cells from Ca(2+) overload under hypoxic stress conditions.
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Affiliation(s)
| | | | | | - Gavin Landesberg
- Physiology, Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Rosario Scalia
- Physiology, Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Reynold A. Panettieri
- the Department of Medicine, University of Pennsylvania School of Medicine, Pennsylvania 19104, and
| | | | - Xiang D. Tang
- the Department of Pharmacology, Nankai University School of Medicine, Tianjin, China
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Breeuwer P, Drocourt J, Rombouts FM, Abee T. A Novel Method for Continuous Determination of the Intracellular pH in Bacteria with the Internally Conjugated Fluorescent Probe 5 (and 6-)-Carboxyfluorescein Succinimidyl Ester. Appl Environ Microbiol 2010; 62:178-83. [PMID: 16535209 PMCID: PMC1388751 DOI: 10.1128/aem.62.1.178-183.1996] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel method based on the intracellular conjugation of the fluorescent probe 5 (and 6-)-carboxyfluorescein succinimidyl ester (cFSE) was developed to determine the intracellular pH of bacteria. cFSE can be taken up by bacteria in the form of its diacetate ester, 5 (and 6-)-carboxyfluorescein diacetate succinimidyl ester, which is subsequently hydrolyzed by esterases to cFSE in the cytoplasm. When Lactococcus lactis cells were permeabilized with ethanol, a significant proportion of cFSE was retained in the cells, which indicated that cFSE was bound intracellularly. Unbound probe could be conveniently extruded by a short incubation of the cells in the presence of a fermentable sugar, most likely by exploiting an active transport system. Such a transport system for cFSE was identified in L. lactis, Listeria innocua, and Bacillus subtilis. The intracellular pH in bacteria can be determined from the ratio of the fluorescence signal at the pH-sensitive wavelength (490 nm) and the fluorescence signal at the pH-insensitive wavelength (440 nm). This cFSE ratio method significantly reduced problems due to the efflux of fluorescent probe from the cells during the measurement. Moreover, the method described was successfully used to determine the intracellular pH in bacteria under stress conditions, such as elevated temperatures and the presence of detergents.
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40
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Walsh CL, Babin BM, Kasinskas RW, Foster JA, McGarry MJ, Forbes NS. A multipurpose microfluidic device designed to mimic microenvironment gradients and develop targeted cancer therapeutics. LAB ON A CHIP 2009; 9:545-54. [PMID: 19190790 PMCID: PMC2855303 DOI: 10.1039/b810571e] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The heterogeneity of cellular microenvironments in tumors severely limits the efficacy of most cancer therapies. We have designed a microfluidic device that mimics the microenvironment gradients present in tumors that will enable the development of more effective cancer therapies. Tumor cell masses were formed within micron-scale chambers exposed to medium perfusion on one side to create linear nutrient gradients. The optical accessibility of the PDMS and glass device enables quantitative transmitted and fluorescence microscopy of all regions of the cell masses. Time-lapse microscopy was used to measure the growth rate and show that the device can be used for long-term efficacy studies. Fluorescence microscopy was used to demonstrate that the cell mass contained viable, apoptotic, and acidic regions similar to in vivo tumors. The diffusion coefficient of doxorubicin was accurately measured, and the accumulation of therapeutic bacteria was quantified. The device is simple to construct, and it can easily be reproduced to create an array of in vitro tumors. Because microenvironment gradients and penetration play critical roles controlling drug efficacy, we believe that this microfluidic device will be vital for understanding the behavior of common cancer drugs in solid tumors and designing novel intratumorally targeted therapeutics.
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Affiliation(s)
- Colin L Walsh
- Department of Chemical Engineering, University of Massachusetts, 159 Goessmann Laboratory, 686 North Pleasant Street. Amherst, MA 01003-9303, USA
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41
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Becker HM, Deitmer JW. Nonenzymatic Proton Handling by Carbonic Anhydrase II during H+-Lactate Cotransport via Monocarboxylate Transporter 1. J Biol Chem 2008; 283:21655-67. [DOI: 10.1074/jbc.m802134200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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42
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Coulon P, Wüsten HJ, Hochstrate P, Dierkes PW. Swelling-activated chloride channels in leech Retzius neurons. ACTA ACUST UNITED AC 2008; 211:630-41. [PMID: 18245640 DOI: 10.1242/jeb.008565] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During periods of high activity neurons are expected to swell due to the uptake of Cl(-). To find out whether leech Retzius neurons possess swelling-activated Cl(-) channels that facilitate Cl(-) efflux and, hence, volume recovery, we exposed the cells to hypotonic solutions. In hypotonic solutions, the cells slowly swelled but did not undergo a regulatory volume decrease. However, the cell volume increased less than predicted for an ideal osmometer, suggesting the action of a compensatory mechanism. The cell swelling was paralleled by a marked decrease in the input resistance as well as by the activation of a membrane current with a reversal potential close to the Cl(-) equilibrium potential. This current was substantially diminished by removing bath Cl(-), by applying the Cl(-) channel blocker DIDS, or by treating the cells with the tubulin polymerization inhibitor colchicine. Furthermore, in the presence of colchicine or vinblastine, the cell swelling was substantially increased. It is concluded that leech Retzius neurons possess swelling-activated Cl(-) channels that require an intact microtubule system for activation. The channels may help to restore cell volume after periods of high neuronal activity.
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Affiliation(s)
- Philippe Coulon
- Institut für Neurobiologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.
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43
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Rochon P, Jourdain M, Mangalaboyi J, Fourrier F, Soulié-Bégu S, Buys B, Dehlin G, Lesage JC, Chambrin MC, Mordon S. Evaluation of BCECF fluorescence ratio imaging to properly measure gastric intramucosal pH variations in vivo. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:064014. [PMID: 18163830 DOI: 10.1117/1.2821698] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Our purpose is to evaluate intramucosal gastric pH video imaging by 2('),7(')-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) fluorescence ratio techniques. We use a video endoscopic imaging system and BCECF as the pH fluorescent probe. Systemic in vivo pH variations are studied in 10 pigs: five in the control group and five with respiratory acidosis induced through rebreathing. The intramucosal pH of the gastric wall is measured every 5 s and the results demonstrate a good correlation (pearson correlation=0.832) between blood gases pH measurements and pH measured with the video endocopic imaging system. Our results confirm the feasibility of using BCECF fluorescence pH imaging to measure intramucosal pH in vivo.
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Affiliation(s)
- Philippe Rochon
- Lille University Hospital, Pavillon Vancostenobel, 59037 Lille Cedex, France
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44
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Lee YK, Kim HL, Kim KO, Sacket SJ, Han MJ, Jo JY, Lim SM, Im DS. N,N-Dimethyl-D-ribo-phytosphingosine Modulates Cellular Functions of 1321N1 Astrocytes. Biomol Ther (Seoul) 2007. [DOI: 10.4062/biomolther.2007.15.2.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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45
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Chang YJ, Lee YK, Lee EH, Park JJ, Chung SK, Im DS. Structure-activity relationships of dimethylsphingosine (DMS) derivatives and their effects on intracellular pH and Ca2+ in the U937 monocyte cell line. Arch Pharm Res 2006; 29:657-65. [PMID: 16964761 DOI: 10.1007/bf02968250] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We recently reported that dimethylsphingosine (DMS), a metabolite of sphingolipids, increased intracellular pH and Ca2+ concentration in U937 human monocytes. In the present study, we found that dimethylphytosphingosine (DMPH) induced the above responses more robustly than DMS. However, phytosphingosine, monomethylphytosphingosine or trimethylsphingosine showed little or no activity. Synthetic C3 deoxy analogues of sphingosine did show similar activities, with the C16 analogue more so than C18. The following structure-activity relationships were observed between DMS derivatives and the intracellular pH and Ca2+ concentrations in U937 monocytes; 1) dimethyl modification is important for the DMS-induced increase of intracellular pH and Ca2+, 2) the addition of an OH group on C4 enhances both activities, 3) the deletion of the OH group on C3 has a negligible effect on the activities, and 4) C16 appears to be more effective than C18. We also found that W-7, a calmodulin inhibitor, blocked the DMS-induced pH increase, whereas, KN-62, ML9, and MMPX, specific inhibitors for calmodulin-dependent kinase II, myosin light chain kinase, and Ca(2+)-calmodulin-dependent phosphodiesterase, respectively, did not affect DMS-induced increases of pH in the U937 monocytes.
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Affiliation(s)
- Young-Ja Chang
- Laboratory of Pharmacology, College of Pharmacy and Research Institute for Drug Development, Pusan National University, Busan 609-735, Korea
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46
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Lee EH, Lee YK, Im YJ, Kim JH, Okajima F, Im DS. Dimethylsphingosine Regulates Intracellular pH and Ca2+ in Human Monocytes. J Pharmacol Sci 2006; 100:289-96. [PMID: 16575153 DOI: 10.1254/jphs.fpj05009x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Dimethylsphingosine (DMS) was first reported as an inhibitor of protein kinase C and later has been used as a specific inhibitor of sphingosine kinase. Furthermore, its anti-cancer effect has become a basis for development of chemotherapy. Nevertheless, its anti-neoplastic mechanism has poorly been understood. In the present study, we observed that DMS increased intracellular pH and Ca(2+) concentration in U937 human monocytes. To further characterize these DMS-induced actions, we employed structurally-related sphingolipids and specific pharmacological tools such as inhibitors of protein kinase C and Na(+)/H(+) exchanger and found that the two responses of DMS were mimicked by four stereoisomers of sphingosine and two isomers to dihydrosphingosine, but not with sphingosine 1-phosphate, sphingosyl-phosphorylcholine, and C2-ceramide. Furthermore, DMS-induced pH increase was independent of Na(+)/H(+) exchanger activity. We also characterized the interrelationship between DMS-induced pH increase and DMS-induced Ca(2+) increase. Since DMS is considered to be a good anti-cancer candidate, our characterization of DMS actions provides useful information for development of DMS chemotherapy.
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Affiliation(s)
- Eun-Hee Lee
- Laboratory of Pharmacology, College of Pharmacy and Research Institute for Drug Development, Pusan National University, Korea
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47
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Froestl B, Steiner B, Müller WE. Enhancement of proteolytic processing of the β-amyloid precursor protein by hyperforin. Biochem Pharmacol 2003; 66:2177-84. [PMID: 14609742 DOI: 10.1016/j.bcp.2003.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We studied the effect of hyperforin, a component of St. John's wort (Hypericum perforatum) extracts, on the processing of the amyloid precursor protein (APP) in rat pheochromocytoma PC12 cells, stably transfected with human wildtype APP. We observed transiently increased release of secretory APP fragments upon hyperforin treatment. Unique features, like a strong reduction of intracellular APP and the time course of soluble APP release, distinguished the effects of hyperforin from those of alkalizing agents and phorbol esters, well known activators of secretory processing of APP. Carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), a protonophore, induced an almost identical decrease in intracellular pH in PC12 cells as does hyperforin. Despite this, FCCP induced a less pronounced release of soluble APP fragments and only slightly reduced intracellular APP levels. These results suggest that hyperforin is an activator of secretory processing of APP with a novel mechanism of action not solely dependent on its effects on intracellular pH.
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Affiliation(s)
- Bettina Froestl
- Department of Pharmacology, Biocenter, University of Frankfurt, Marie-Curie-Str. 9, D-60439 Frankfurt, Germany
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48
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Konstantinou-Tegou A, Kaloyianni M, Bourikas D, Koliakos G. The effect of leptin on Na(+)-H(+) antiport (NHE 1) activity of obese and normal subjects erythrocytes. Mol Cell Endocrinol 2001; 183:11-8. [PMID: 11604219 DOI: 10.1016/s0303-7207(01)00639-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Obesity is currently considered as a chronic metabolic disease, associated with a high risk of cardiovascular complications. Leptin, an adipocyte-derived hormone has a variety target cells influencing a wide range of processes. Possible counteractions of hyperleptinaemia are currently investigated. The Na(+)-H(+) exchanger (NHE 1) is involved in multiple cellular functions and its activation has been related to hypertension and obesity. NHE 1 is present on erythrocytes and can be stimulated by various hormones. Erythrocytes have on their surface a variety of receptors with mostly unknown function. In the present paper, the effect of leptin on erythrocytes NHE 1 activity has been investigated. For this reason, the intracellular pH and sodium influxes were measured before and after addition of leptin in erythrocyte suspensions from normal and obese individuals. Amiloride, a specific NHE 1 inhibitor, and staurosporine a protein kinase C inhibitor were used to inhibit erythrocyte NHE 1. For the binding study leptin was labeled with fluorescein isothiocyanate (FITC) and the binding on erythrocytes was estimated by Scatchard analysis. NHE 1 activity increased in the presence of leptin but significantly less in the obese than in the control group. Furthermore the concentrations of leptin binding sites on the surface of erythrocytes were lower in erythrocytes drawn from obese individuals than in erythrocytes drawn from normal subjects. Since NHE 1 activity has been associated with insulin resistance and hypertension, the activation of this antiport by leptin may represent a link between adipose tissue hypertrophy and cardiovascular complications of obesity.
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Affiliation(s)
- A Konstantinou-Tegou
- Laboratory of Animal Physiology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki 54006, Greece
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49
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Hotta Y, Ishikawa N, Ohashi N, Matsui K. Effects of SM-20550, a selective Na+-H+ exchange inhibitor, on the ion transport of myocardial mitochondria. Mol Cell Biochem 2001; 219:83-90. [PMID: 11354258 DOI: 10.1023/a:1011019010140] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The effect of a novel Na+-H+ exchange inhibitor, SM-20550 [N-(aminoiminomethyl)-1,4-dimethyl-1H-indole-2-carboxamide methanesulfonate] (SM) on the ion transport of myocardial mitochondria was studied using ion fluorometry and superfusion techniques. Isolated mitochondria from the guinea-pig heart were pre-loaded with fluoroprobes of either BCECF AM for H+, SBFI AM for Na+ or fura-2 AM for Ca2+. Initially, the treated mitochondria were superfused with a normal medium (MOPS-buffer, pH 7.4, 24 degrees C), subsequently fluorometric experiments on the Na+, H+, Ca2+ mobilization across the mitochondrial membrane were performed. The intramitochondrial pH (pHm) was increased by the superfusion of Na+ at physiological cytosolic concentrations of 10 mM, indicating the existence of a Na+-H+ exchange in mitochondrial membranes. The Na+ induced elevation of pH was dose-dependently inhibited by SM 1 microM (delta pHm; 45% as drug-free 100%), and 10 microM (delta pHm; 70%), as observed in our experiments with the myocardial sarcolemmal membrane. The selective Na+-H+ exchange inhibitor SM reduced such pHm elevations more markedly than that of EIPA [5-(N-ethyl-N-isopropyl) amiloride]. The Na+-H+ exchange inhibitors, SM and EIPA suppressed the intramitochondrial Ca2+ elevation ([Ca2+]m) brought on by external Ca2+ concentration changes: The pretreatment with SM 1 microM, 10 microM and EIPA 10 microM reduced the [Ca2+]m influx by 28.3, 56.5 and 63%, respectively. Additionally, the [Ca2+]m elevation induced by acidification of the perfusate was reduced by the prior infusion of SM and EIPA. Pretreatment of mitochondria with SM or EIPA which had beneficial effects on the left ventricular developed pressure (LVDP) in the ischemia-reperfusion injury of Langendorff hearts, reduced the intramitochondrial Na+ and pHm levels, indicating interplay of the inhibitory mechanism of Ca2+-uptake into mitochondria coupled with Na+-H+ exchange. These findings suggested that protective effects of Na+-H+ exchange inhibitors on reperfused myocardium are due in part to the Ca2+-paradox at the mitochondria level.
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Affiliation(s)
- Y Hotta
- Department of Pharmacology, Aichi Medical University School of Medicine, Nagakute, Japan
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50
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Axelsson MA, Karlsson NG, Steel DM, Ouwendijk J, Nilsson T, Hansson GC. Neutralization of pH in the Golgi apparatus causes redistribution of glycosyltransferases and changes in the O-glycosylation of mucins. Glycobiology 2001; 11:633-44. [PMID: 11479274 DOI: 10.1093/glycob/11.8.633] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Addition of the weak base ammonium chloride (NH4Cl) or the proton pump inhibitor bafilomycin A1 to cultured HeLa and LS 174T cells effectively neutralized the pH gradient of the secretory pathway. This resulted in relocalization of the three studied glycosyltransferases, N-acetylgalactosaminyltransferase 2, beta1,2 N-acetylglucosaminyltransferase I, and beta1,4 galactosyltransferase 1, normally localized to the Golgi stack, the medial/trans-Golgi and the trans-Golgi/TGN, respectively. Indirect immunofluorescence microscopy, immunoelectron microscopy, and subcellular fractionation of the tagged or native glycosyltransferases showed that NH4Cl caused a relocalization of the enzymes mainly to vesicles of endosomal type, whereas bafilomycin A1 gave mainly cell surface staining. The general morphology of the endoplasmic reticulum and Golgi apparatus was retained as judged from immunofluorescence and electron microscopy studies. When the O-glycans on the guanidinium chloride insoluble gel-forming mucins from the LS 174T cells were analyzed by gas chromatography-mass spectrometry after neutralization of the secretory pathway pH by NH4Cl over 10 days shorter O-glycans were observed. However, no decrease in the number of oligosaccharide chains was indicated. Together, the results suggest that pH is a contributing factor for proper steady-state distribution of glycosyltransferases over the Golgi apparatus and that altered pH may cause alterations in glycosylation possibly due to a relocalization of glycosyltransferases.
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Affiliation(s)
- M A Axelsson
- Department of Medical Biochemistry, Göteborg University, P.O. Box 440, 405 30 Gothenburg, Sweden
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