1
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Zhang L, Guo J, You Q, Xu Y. A water-soluble fluorescent pH probe and its application for monitoring lysosomal pH changes in living cells. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2023. [PMID: 37317586 DOI: 10.1039/d3ay00343d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Intracellular pH plays a crucial role in many cellular processes, and abnormal intracellular pH has been linked to common diseases such as cancer and Alzheimer's. To address this issue, a water-soluble fluorescent pH probe was designed based on the protonation/deprotonation of the 4-methylpiperazin-1-yl group, using dicyanoisophorone as the fluorophore. In the neutral form of the probe, fluorescence is quenched due to charge transfer from the 4-methylpiperazin-1-yl group to the fluorophore upon excitation. Under acidic conditions, protonation of the 4-methylpiperazin-1-yl group inhibits the photoinduced electron transfer process, leading to an increase in fluorescence intensity. Density-functional theory calculations also verified the fluorescence OFF-ON mechanism. The probe exhibits high selectivity, photostability, fast response to pH changes, and low cytotoxicity to cells. Additionally, the probe selectively accumulates in lysosomes, with a high Pearson coefficient (0.95) using LysoTracker Green DND-26 as a reference. Notably, the probe can monitor lysosomal pH changes in living cells and track pH changes stimulated by chloroquine. We anticipate that the probe has potential for diagnosing pH-related diseases.
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Affiliation(s)
- Lei Zhang
- Department of Biology, Xinzhou Teachers University, Xinzhou, Shanxi Province 034000, P. R. of China
| | - Jun Guo
- ShanXi Weipu Testing Technology Co. Ltd, Taiyuan, Shanxi Province 030012, P. R. of China
| | - Qihua You
- College of Environment and Public Health, Xiamen Huaxia University, Xiamen, Fujian Province 361024, P. R. of China.
| | - Yuqing Xu
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai, Shandong Province 264025, P. R. of China
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2
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Abstract
Significance: Cancer-associated tissue-specific lactic acidosis stimulates and mediates tumor invasion and metastasis and is druggable. Rarely, malignancy causes systemic lactic acidosis, the role of which is poorly understood. Recent Advances: The understanding of the role of lactate has shifted dramatically since its discovery. Long recognized as only a waste product, lactate has become known as an alternative metabolism substrate and a secreted nutrient that is exchanged between the tumor and the microenvironment. Tissue-specific lactic acidosis is targeted to improve the host body's anticancer defense and serves as a tool that allows the targeting of anticancer compounds. Systemic lactic acidosis is associated with poor survival. In patients with solid cancer, systemic lactic acidosis is associated with an extremely poor prognosis, as revealed by the analysis of 57 published cases in this study. Although it is considered a pathology worth treating, targeting systemic lactic acidosis in patients with solid cancer is usually inefficient. Critical Issues: Research gaps include simple questions, such as the unknown nuclear pH of the cancer cells and its effects on chemotherapy outcomes, pH sensitivity of glycosylation in cancer cells, in vivo mechanisms of response to acidosis in the absence of lactate, and overinterpretation of in vitro results that were obtained by using cells that were not preadapted to acidic environments. Future Directions: Numerous metabolism-targeting anticancer compounds induce lactatemia, lactic acidosis, or other types of acidosis. Their potential to induce acidic environments is largely overlooked, although the acidosis might contribute to a substantial portion of the observed clinical effects. Antioxid. Redox Signal. 37, 1130-1152.
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Affiliation(s)
- Petr Heneberg
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
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3
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Jia Y, Shen Y, Zhu Y, Wang J. Covalent organic framework-based fluorescent nanoprobe for intracellular pH sensing and imaging. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 272:121002. [PMID: 35168035 DOI: 10.1016/j.saa.2022.121002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/25/2022] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
Lysosomes are the acidic organelles in the cells that play an important role in intracellular degradation and other various cellular functions. The pH disturbance of lysosomes will result in the lysosomal dysfunction and many lysosomal related diseases. In this work, we reported a methoxy-based covalent organic framework (TAPB-DMTP-COF) that a novel pH-responsive fluorescent probe for lysosomal pH imaging in cells. The prepared TAPB-DMTP-COF presented regular crystal structure, low toxicity and good pH responsive property. The rich imine structure in the material enabled pH-responsive properties of the TAPB-DMTP-COF and made it exhibited pH-dependent fluorescence response. Good detection linearity for pH measurements in aqueous solution was achieved by this probe. Moreover, the TAPB-DMTP-COF can be used for the selective lysosomal pH imaging. Confocal fluorescence imaging results demonstrated that the pH fluctuations (from 4.0 to 7.4) and the pH changes in lysosomes can be effectively monitored in situ by the developed probe. This study may provide a new avenue for the intracellular pH sensing, deep study and understanding about the mechanism of diseases related to abnormal lysosomal pH.
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Affiliation(s)
- Yutao Jia
- School of Pharmacy, Key Laboratory of Innovative Drug Development and Evaluation, Hebei Medical University, Shijiazhuang 050017, People's Republic of China; College of Chemical Technology, Shijiazhuang University, Shijiazhuang 050035, People's Republic of China
| | - Yanting Shen
- School of Pharmacy, Key Laboratory of Innovative Drug Development and Evaluation, Hebei Medical University, Shijiazhuang 050017, People's Republic of China; Postdoctoral Mobile Station of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, People's Republic of China.
| | - Yanyan Zhu
- School of Pharmacy, Key Laboratory of Innovative Drug Development and Evaluation, Hebei Medical University, Shijiazhuang 050017, People's Republic of China
| | - Jing Wang
- School of Pharmacy, Key Laboratory of Innovative Drug Development and Evaluation, Hebei Medical University, Shijiazhuang 050017, People's Republic of China.
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4
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Su T, Huang S, Zhang Y, Guo Y, Zhang S, Guan J, Meng M, Liu L, Wang C, Yu D, Kwan HY, Huang Z, Huang Q, Lai-Han Leung E, Hu M, Wang Y, Liu Z, Lu L. miR-7/TGF- β2 axis sustains acidic tumor microenvironment-induced lung cancer metastasis. Acta Pharm Sin B 2022; 12:821-837. [PMID: 35251919 PMCID: PMC8896986 DOI: 10.1016/j.apsb.2021.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/23/2021] [Accepted: 05/19/2021] [Indexed: 12/26/2022] Open
Abstract
Acidosis, regardless of hypoxia involvement, is recognized as a chronic and harsh tumor microenvironment (TME) that educates malignant cells to thrive and metastasize. Although overwhelming evidence supports an acidic environment as a driver or ubiquitous hallmark of cancer progression, the unrevealed core mechanisms underlying the direct effect of acidification on tumorigenesis have hindered the discovery of novel therapeutic targets and clinical therapy. Here, chemical-induced and transgenic mouse models for colon, liver and lung cancer were established, respectively. miR-7 and TGF-β2 expressions were examined in clinical tissues (n = 184). RNA-seq, miRNA-seq, proteomics, biosynthesis analyses and functional studies were performed to validate the mechanisms involved in the acidic TME-induced lung cancer metastasis. Our data show that lung cancer is sensitive to the increased acidification of TME, and acidic TME-induced lung cancer metastasis via inhibition of miR-7-5p. TGF-β2 is a direct target of miR-7-5p. The reduced expression of miR-7-5p subsequently increases the expression of TGF-β2 which enhances the metastatic potential of the lung cancer. Indeed, overexpression of miR-7-5p reduces the acidic pH-enhanced lung cancer metastasis. Furthermore, the human lung tumor samples also show a reduced miR-7-5p expression but an elevated level of activated TGF-β2; the expressions of both miR-7-5p and TGF-β2 are correlated with patients' survival. We are the first to identify the role of the miR-7/TGF-β2 axis in acidic pH-enhanced lung cancer metastasis. Our study not only delineates how acidification directly affects tumorigenesis, but also suggests miR-7 is a novel reliable biomarker for acidic TME and a novel therapeutic target for non-small cell lung cancer (NSCLC) treatment. Our study opens an avenue to explore the pH-sensitive subcellular components as novel therapeutic targets for cancer treatment.
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Key Words
- AOM/DSS, azoxymethane/dextran sodium sulfate
- Acidic tumor microenvironment
- B[a]P, benzopyrene
- CA9, carbonic anhydrase IX
- DAB, diaminobenzidine
- DAVID, Database for Annotation, Visualization, and Integrated Discovery
- DEGs, differentially expressed genes
- DEN, diethylnitrosamine
- DEPs, differentially expressed proteins
- DSS, dextran sodium sulfate
- GEMMs, genetically engineered tumor mouse models
- GSEA, gene set enrichment analysis
- IHC, immunohistochemistry
- ISH, in situ hybridization
- Invasion
- KEGG, Kyoto Encyclopedia of Genes and Genomes
- LUAD, lung adenocarcinoma
- LUSC, lung squamous cell carcinoma
- Lung cancer
- MCT, monocarboxylate transporter
- Metastasis
- NHE, Na+/H+ exchanger
- NSCLC, non-small cell lung cancer
- PCR, polymerase chain reaction
- TGF-β2
- TME, tumor microenvironment
- TMT, tandem mass tagging
- V-ATPase, vacuolar ATPase
- miR-7-5p
- pH
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5
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Davis CM, Gruebele M. Cellular Sticking Can Strongly Reduce Complex Binding by Speeding Dissociation. J Phys Chem B 2021; 125:3815-3823. [PMID: 33826329 DOI: 10.1021/acs.jpcb.1c00950] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
While extensive studies have been carried out to determine protein-RNA binding affinities, mechanisms, and dynamics in vitro, such studies do not take into consideration the effect of the many weak nonspecific interactions in a cell filled with potential binding partners. Here we experimentally tested the role of the cellular environment on affinity and binding dynamics between a protein and RNA in living U-2 OS cells. Our model system is the spliceosomal protein U1A and its binding partner SL2 of the U1 snRNA. The binding equilibrium was perturbed by a laser-induced temperature jump and monitored by Förster resonance energy transfer. The apparent binding affinity in live cells was reduced by up to 2 orders of magnitude compared to in vitro. The measured in-cell dissociation rate coefficients were up to 2 orders of magnitude larger, whereas no change in the measured association rate coefficient was observed. The latter is not what would be anticipated due to macromolecular crowding or nonspecific sticking of the uncomplexed U1A and SL2 in the cell. A quantitative model fits our experimental results, with the major cellular effect being that U1A and SL2 sticking to cellular components are capable of binding, just not as strongly as the free complex. This observation suggests that high binding affinities measured or designed in vitro are necessary for proper binding in vivo, where competition with many nonspecific interactions exists, especially for strongly interacting species with high charge or large hydrophobic surface areas.
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6
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Studying Proton Gradients Across the Nuclear Envelope. Methods Mol Biol 2021; 2175:47-63. [PMID: 32681483 DOI: 10.1007/978-1-0716-0763-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The existence of nuclear pore complexes in the nuclear envelope has led to the assumption that ions move freely from the cytosol into the nucleus, and that the molecular mechanisms at the plasma membrane that regulate cytosolic pH also regulate nuclear pH. Furthermore, studies to measure pH in the nucleus have produced contradictory results, since it has been found that the nuclear pH is either similar to the cytosol or more alkaline than the cytosol. However, most studies of nuclear pH have lacked the rigor needed to understand pH regulation in the nucleus. A major problem has been the lack of in situ titrations in the nucleus and cytosol, since the intracellular environment is different in the cytosol and nucleus and the behavior of fluorescent pH probes is different in these environments. Here we present a method that uses the fluorescence of SNARF-1 that labels both cytosol and nucleus. Using ratio imaging microscopy, regions of interest corresponding to the nucleus and cytosol to perform steady-state pH measurements followed by in situ titrations, to correctly assign pH in those cellular domains.
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7
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Halcrow PW, Geiger JD, Chen X. Overcoming Chemoresistance: Altering pH of Cellular Compartments by Chloroquine and Hydroxychloroquine. Front Cell Dev Biol 2021; 9:627639. [PMID: 33634129 PMCID: PMC7900406 DOI: 10.3389/fcell.2021.627639] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/18/2021] [Indexed: 12/12/2022] Open
Abstract
Resistance to the anti-cancer effects of chemotherapeutic agents (chemoresistance) is a major issue for people living with cancer and their providers. A diverse set of cellular and inter-organellar signaling changes have been implicated in chemoresistance, but it is still unclear what processes lead to chemoresistance and effective strategies to overcome chemoresistance are lacking. The anti-malaria drugs, chloroquine (CQ) and its derivative hydroxychloroquine (HCQ) are being used for the treatment of various cancers and CQ and HCQ are used in combination with chemotherapeutic drugs to enhance their anti-cancer effects. The widely accepted anti-cancer effect of CQ and HCQ is their ability to inhibit autophagic flux. As diprotic weak bases, CQ and HCQ preferentially accumulate in acidic organelles and neutralize their luminal pH. In addition, CQ and HCQ acidify the cytosolic and extracellular environments; processes implicated in tumorigenesis and cancer. Thus, the anti-cancer effects of CQ and HCQ extend beyond autophagy inhibition. The present review summarizes effects of CQ, HCQ and proton pump inhibitors on pH of various cellular compartments and discuss potential mechanisms underlying their pH-dependent anti-cancer effects. The mechanisms considered here include their ability to de-acidify lysosomes and inhibit autophagosome lysosome fusion, to de-acidify Golgi apparatus and secretory vesicles thus affecting secretion, and to acidify cytoplasm thus disturbing aerobic metabolism. Further, we review the ability of these agents to prevent chemotherapeutic drugs from accumulating in acidic organelles and altering their cytosolic concentrations.
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Affiliation(s)
| | | | - Xuesong Chen
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, United States
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8
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Wang N, Yu X, Deng T, Zhang K, Yang R, Li J. Two-Photon Excitation/Red Emission, Ratiometric Fluorescent Nanoprobe for Intracellular pH Imaging. Anal Chem 2019; 92:583-587. [DOI: 10.1021/acs.analchem.9b04782] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ningning Wang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Chemical Biology and Nanomedicine, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Xinyan Yu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Chemical Biology and Nanomedicine, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Ting Deng
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Chemical Biology and Nanomedicine, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Ke Zhang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Chemical Biology and Nanomedicine, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
| | - Ronghua Yang
- School of Chemistry and Biological Engineering, Changsha University of Science and Technology, Changsha 410114, P. R. China
| | - Jishan Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Institute of Chemical Biology and Nanomedicine, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
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9
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BODIPY-derived ratiometric fluorescent sensors: pH-regulated aggregation-induced emission and imaging application in cellular acidification triggered by crystalline silica exposure. Sci China Chem 2018. [DOI: 10.1007/s11426-018-9284-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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10
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You Q, Shen J, Shen G, Peng L, Lu Y, Fu Q, Xu Y, Zhang L. A Colorimetric and Fluorescent pH Probe for Extremely Acidic Conditions and its Application in pH Test Paper. B KOREAN CHEM SOC 2018. [DOI: 10.1002/bkcs.11395] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Qihua You
- Department of Science and Technology for Inspection; Xiamen Huaxia University; Xiamen 361024 China
| | - Jinhai Shen
- Department of Science and Technology for Inspection; Xiamen Huaxia University; Xiamen 361024 China
| | - Ganping Shen
- Department of Science and Technology for Inspection; Xiamen Huaxia University; Xiamen 361024 China
| | - Liyun Peng
- Department of Science and Technology for Inspection; Xiamen Huaxia University; Xiamen 361024 China
| | - Yuanqin Lu
- Department of Science and Technology for Inspection; Xiamen Huaxia University; Xiamen 361024 China
| | - Qi Fu
- Department of Science and Technology for Inspection; Xiamen Huaxia University; Xiamen 361024 China
| | - Yuqing Xu
- School of Physics and Optoelectronics Engineering; Ludong University; Yantai 264025 China
| | - Lei Zhang
- Biology Institute of Shanxi; Taiyuan 030006 China
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11
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Wen Y, Zhang W, Liu T, Huo F, Yin C. Pinpoint Diagnostic Kit for Heat Stroke by Monitoring Lysosomal pH. Anal Chem 2017; 89:11869-11874. [PMID: 28992693 DOI: 10.1021/acs.analchem.7b03612] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Heat stroke is one of the most serious causes of mortality. To prevent the situation, it is fundamental to research the mechanism of heat cytotoxicity. The preliminary results revealed that heat stroke and the change of lysosome acidity had some certain correlation. To further clarify their relationship, herein, we report a highly selective and sensitive fluorescence probe (NT1) for turn-on sensing of the pH value. NT2 was synthesized as control compound. Compared to NT2, NT1 showed accurate lysosome target ability. In addition, the suitable pKa value (5.67) allows NT1 to response to the changes of lysosomal pH values. Most importantly, NT1 could be used to study the correlation between the change of lysosomal pH and heat stroke. It was shown that the lysosomal pH value increasing with temperature during heat stroke. Thus, NT1 was an excellent candidate for research of the complex biological mechanism of heat stroke.
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Affiliation(s)
- Ying Wen
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province, Institute of Molecular Science, Shanxi University , Taiyuan 030006, China
| | - Weijie Zhang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province, Institute of Molecular Science, Shanxi University , Taiyuan 030006, China
| | - Tao Liu
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province, Institute of Molecular Science, Shanxi University , Taiyuan 030006, China
| | - Fangjun Huo
- Research Institute of Applied Chemistry, Shanxi University , Taiyuan 030006, China
| | - Caixia Yin
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province, Institute of Molecular Science, Shanxi University , Taiyuan 030006, China
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12
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Nuclear carbonic anhydrase 6B associates with PRMT5 to epigenetically promote IL-12 expression in innate response. Proc Natl Acad Sci U S A 2017; 114:8620-8625. [PMID: 28739930 DOI: 10.1073/pnas.1700917114] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Interleukin-12 (IL-12) is critical for induction of protective immunity against intracellular bacterial infection. However, the mechanisms for efficient induction of IL-12 in innate response remain poorly understood. Here we report that the B type of carbonic anhydrase 6 (Car6-b, which encoded CA-VI B) is essential for host defense against Listeria monocytogenes (LM) infection by epigenetically promoting IL-12 expression independent of its carbonic anhydrase activity. Deficiency of Car6-b attenuated IL-12 production upon LM infection both in vitro and in vivo. Car6-/- mice were more susceptible to LM infection with less production of IL-12. Mechanistically, the nuclear localized CA-VI B selectively promotes IL-12 expression by interaction with protein arginine N-methyltransferase 5 (PRMT5), which reduces symmetric dimethylation of histone H3 arginine 8 modification (H3R8me2s) at Il12 promoters to facilitate chromatin accessibility, selectively enhancing c-Rel binding to the Il12b promoter. Our findings add insights to the epigenetic regulation of IL-12 induction in innate immunity.
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13
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Nakamura A, Tsukiji S. Ratiometric fluorescence imaging of nuclear pH in living cells using Hoechst-tagged fluorescein. Bioorg Med Chem Lett 2017; 27:3127-3130. [DOI: 10.1016/j.bmcl.2017.05.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 01/03/2023]
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14
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Żurawik TM, Pomorski A, Belczyk-Ciesielska A, Goch G, Niedźwiedzka K, Kucharczyk R, Krężel A, Bal W. Revisiting Mitochondrial pH with an Improved Algorithm for Calibration of the Ratiometric 5(6)-carboxy-SNARF-1 Probe Reveals Anticooperative Reaction with H+ Ions and Warrants Further Studies of Organellar pH. PLoS One 2016; 11:e0161353. [PMID: 27557123 PMCID: PMC4996429 DOI: 10.1371/journal.pone.0161353] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/03/2016] [Indexed: 11/18/2022] Open
Abstract
Fluorescence measurements of pH and other analytes in the cell rely on accurate calibrations, but these have routinely used algorithms that inadequately describe the properties of indicators. Here, we have established a more accurate method for calibrating and analyzing data obtained using the ratiometric probe 5(6)-carboxy-SNARF-1. We tested the implications of novel approach to measurements of pH in yeast mitochondria, a compartment containing a small number of free H+ ions. Our findings demonstrate that 5(6)-carboxy-SNARF-1 interacts with H+ ions inside the mitochondria in an anticooperative manner (Hill coefficient n of 0.5) and the apparent pH inside the mitochondria is ~0.5 unit lower than had been generally assumed. This result, at odds with the current consensus on the mechanism of energy generation in the mitochondria, is in better agreement with theoretical considerations and warrants further studies of organellar pH.
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Affiliation(s)
- Tomasz Michał Żurawik
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Adam Pomorski
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14A, 50-383, Wrocław, Poland
| | | | - Grażyna Goch
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Katarzyna Niedźwiedzka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Róża Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
| | - Artur Krężel
- Department of Chemical Biology, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie 14A, 50-383, Wrocław, Poland
- * E-mail: (AK); (WB)
| | - Wojciech Bal
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106, Warsaw, Poland
- * E-mail: (AK); (WB)
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15
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Santos JM, Martínez-Zaguilán R, Facanha AR, Hussain F, Sennoune SR. Vacuolar H+-ATPase in the nuclear membranes regulates nucleo-cytosolic proton gradients. Am J Physiol Cell Physiol 2016; 311:C547-C558. [PMID: 27510904 DOI: 10.1152/ajpcell.00019.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 06/26/2016] [Indexed: 01/01/2023]
Abstract
The regulation of the luminal pH of each organelle is crucial for its function and must be controlled tightly. Nevertheless, it has been assumed that the nuclear pH is regulated by the cytoplasmic proton transporters via the diffusion of H+ across the nuclear pores because of their large diameter. However, it has been demonstrated that ion gradients exist between cytosol and nucleus, suggesting that the permeability of ions across the nuclear pores is restricted. Vacuolar H+-ATPase (V-H+-ATPase) is responsible for the creation and maintenance of trans-membrane electrochemical gradient. We hypothesize that V-H+-ATPase located in the nuclear membranes functions as the primary mechanism to regulate nuclear pH and generate H+ gradients across the nuclear envelope. We studied the subcellular heterogeneity of H+ concentration in the nucleus and cytosol using ratio imaging microscopy and SNARF-1, a pH indicator, in prostate cells. Our results indicate that there are proton gradients across the nuclear membranes that are generated by V-H+-ATPase located in the outer and inner nuclear membranes. We demonstrated that these gradients are mostly dissipated by inhibiting V-H+-ATPase. Immunoblots and V-H+-ATPase activity corroborated the existence of V-H+-ATPase in the nuclear membranes. This study demonstrates that V-H+-ATPase is functionally expressed in nuclear membranes and is responsible for nuclear H+ gradients that may promote not only the coupled transport of substrates, but also most electrochemically driven events across the nuclear membranes. This study represents a paradigm shift that the nucleus can regulate its own pH microenvironment, providing new insights into nuclear ion homeostasis and signaling.
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Affiliation(s)
- Julianna Maria Santos
- Cell Physiology and Molecular Biophysics Department, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Raul Martínez-Zaguilán
- Cell Physiology and Molecular Biophysics Department, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Arnoldo Rocha Facanha
- Biosciences and Biotechnology Center, Cell Biology and Tissue Laboratory, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Rio de Janeiro, Brazil; and
| | - Fazle Hussain
- Mechanical Engineering Department, Texas Tech University, Lubbock, Texas
| | - Souad R Sennoune
- Cell Physiology and Molecular Biophysics Department, Texas Tech University Health Sciences Center, Lubbock, Texas;
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16
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Tu Y, Peng F, Adawy A, Men Y, Abdelmohsen LKEA, Wilson DA. Mimicking the Cell: Bio-Inspired Functions of Supramolecular Assemblies. Chem Rev 2015; 116:2023-78. [DOI: 10.1021/acs.chemrev.5b00344] [Citation(s) in RCA: 211] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Yingfeng Tu
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Fei Peng
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Alaa Adawy
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Yongjun Men
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Loai K. E. A. Abdelmohsen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Daniela A. Wilson
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
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Dynnik VV, Kononov AV, Sergeev AI, Teplov IY, Tankanag AV, Zinchenko VP. To Break or to Brake Neuronal Network Accelerated by Ammonium Ions? PLoS One 2015. [PMID: 26217943 PMCID: PMC4517767 DOI: 10.1371/journal.pone.0134145] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Purpose The aim of present study was to investigate the effects of ammonium ions on in vitro neuronal network activity and to search alternative methods of acute ammonia neurotoxicity prevention. Methods Rat hippocampal neuronal and astrocytes co-cultures in vitro, fluorescent microscopy and perforated patch clamp were used to monitor the changes in intracellular Ca2+- and membrane potential produced by ammonium ions and various modulators in the cells implicated in neural networks. Results Low concentrations of NH4Cl (0.1–4 mM) produce short temporal effects on network activity. Application of 5–8 mM NH4Cl: invariably transforms diverse network firing regimen to identical burst patterns, characterized by substantial neuronal membrane depolarization at plateau phase of potential and high-amplitude Ca2+-oscillations; raises frequency and average for period of oscillations Ca2+-level in all cells implicated in network; results in the appearance of group of «run out» cells with high intracellular Ca2+ and steadily diminished amplitudes of oscillations; increases astrocyte Ca2+-signalling, characterized by the appearance of groups of cells with increased intracellular Ca2+-level and/or chaotic Ca2+-oscillations. Accelerated network activity may be suppressed by the blockade of NMDA or AMPA/kainate-receptors or by overactivation of AMPA/kainite-receptors. Ammonia still activate neuronal firing in the presence of GABA(A) receptors antagonist bicuculline, indicating that «disinhibition phenomenon» is not implicated in the mechanisms of networks acceleration. Network activity may also be slowed down by glycine, agonists of metabotropic inhibitory receptors, betaine, L-carnitine, L-arginine, etc. Conclusions Obtained results demonstrate that ammonium ions accelerate neuronal networks firing, implicating ionotropic glutamate receptors, having preserved the activities of group of inhibitory ionotropic and metabotropic receptors. This may mean, that ammonia neurotoxicity might be prevented by the activation of various inhibitory receptors (i.e. by the reinforcement of negative feedback control), instead of application of various enzyme inhibitors and receptor antagonists (breaking of neural, metabolic and signaling systems).
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Affiliation(s)
- Vladimir V. Dynnik
- Laboratory of intracellular signaling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
- Laboratory of bioenergetics, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
- * E-mail:
| | - Alexey V. Kononov
- Laboratory of intracellular signaling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Alexander I. Sergeev
- Laboratory of intracellular signaling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Iliya Y. Teplov
- Laboratory of intracellular signaling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Arina V. Tankanag
- Laboratory of intracellular signaling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Valery P. Zinchenko
- Laboratory of intracellular signaling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
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You QH, Lee YM, Chan WH, Mak NK, Lee AWM, Hau SCK, Mak TCW. A colorimetric and ratiometric fluorescent pH probe based on ring opening/closing approach and its applications in monitoring cellular pH change. RSC Adv 2015. [DOI: 10.1039/c4ra13445a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A cell permeable colorimetric and ratiometric fluorescent pH probe with a pKavalue of 6.0 has been developed.
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Affiliation(s)
- Qi-Hua You
- Department of Chemistry
- Hong Kong Baptist University
- Kowloon Tong
- China
- Partner State Key Laboratory of Environmental and Bioanalysis
| | - Yee Man Lee
- Department of Biology
- Hong Kong Baptist University
- Kowloon Tong
- China
| | - Wing Hong Chan
- Department of Chemistry
- Hong Kong Baptist University
- Kowloon Tong
- China
- Partner State Key Laboratory of Environmental and Bioanalysis
| | - Nai Ki Mak
- Department of Biology
- Hong Kong Baptist University
- Kowloon Tong
- China
| | - Albert W. M. Lee
- Department of Chemistry
- Hong Kong Baptist University
- Kowloon Tong
- China
| | - Sam C. K. Hau
- Department of Chemistry
- Hong Kong Baptist University
- Kowloon Tong
- China
- Department of Chemistry
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Wan Q, Chen S, Shi W, Li L, Ma H. Lysosomal pH Rise during Heat Shock Monitored by a Lysosome-Targeting Near-Infrared Ratiometric Fluorescent Probe. Angew Chem Int Ed Engl 2014; 53:10916-20. [DOI: 10.1002/anie.201405742] [Citation(s) in RCA: 334] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/29/2014] [Indexed: 12/12/2022]
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20
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Wan Q, Chen S, Shi W, Li L, Ma H. Lysosomal pH Rise during Heat Shock Monitored by a Lysosome-Targeting Near-Infrared Ratiometric Fluorescent Probe. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201405742] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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21
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Marina OC, Sanders CK, Mourant JR. Effects of acetic acid on light scattering from cells. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:085002-1. [PMID: 23224185 PMCID: PMC3414239 DOI: 10.1117/1.jbo.17.8.085002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/14/2012] [Accepted: 07/20/2012] [Indexed: 05/03/2023]
Abstract
Acetic acid has been used for decades as an aid for the detection of precancerous cervical lesions, and the use of acetic acid is being investigated in several other tissues. Nonetheless, the mechanism of acetowhitening is unclear. This work tests some of the hypotheses in the literature and measures changes in light scattering specific to the nucleus and the cytoplasm. Wide angle side scattering from both the nucleus and the cytoplasm increases with acetic application to tumorigenic cells, with the increase in nuclear scattering being greater. In one cell line, the changes in nuclear scattering are likely due to an increase in number or scattering efficiency of scattering centers smaller than the wavelength of excitation light. There are likely several cellular changes that cause acetowhitening and the cellular changes may differ with cell type. These results should lead to a better understanding of acetowhitening and potentially the development of adjunct techniques to improve the utility of acetic acid application. For the well-studied case of cervical tissue, acetowhitening has been shown to be sensitive, but not specific for oncogenic changes needing treatment.
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Affiliation(s)
- Oana C. Marina
- Los Alamos National Laboratory, Bioscience Division, MS M888, Los Alamos, New Mexico 87544
| | - Claire K. Sanders
- Los Alamos National Laboratory, Bioscience Division, MS M888, Los Alamos, New Mexico 87544
| | - Judith R. Mourant
- Los Alamos National Laboratory, Bioscience Division, MS M888, Los Alamos, New Mexico 87544
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22
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Affiliation(s)
- Junyan Han
- Department of Chemistry, Texas A&M University, Box 30012, College Station, Texas 77841, USA
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23
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Direct pH measurements by using subcellular targeting of 5(and 6-) carboxyseminaphthorhodafluor in mammalian cells. Biotechniques 2009; 47:769-74. [DOI: 10.2144/000113220] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
As a means of reliably measuring intracellular pH, we have precisely targeted 5(and 6-) carboxyseminaphthorhodafluor to cellular subcompartments. This was accomplished by combining the well-established pH-sensitive dye with a protein-based reporter system. When expressed in cells, the reporter protein is designed to covalently bind ligands composed of a functional group and a reactive linker. In order to make a pH-sensitive ligand, we chemically coupled the pH sensor to a reactive linker. Several ligands of differing linker lengths were made and tested for their pH responsiveness in vitro. The most responsive of these ligands was then evaluated for its efficacy in live cell labeling and its use as an intracellular pH sensor for ratiometric confocal microscopy. Here we show that we could target this pH sensor within mammalian cells exclusively to either the nucleus or cytoplasm. Exhibiting the versatility of this reporter technology, we were also able to specifically limit pH sensor labeling to within the trafficking pathway of integrins and directly measure pH of this environment. Results correspond well with previously published reports. Both the simplicity and flexibility of the technology used in this study make possible the development of diverse targeted microenvironmental sensors or other moieties of interest.
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Bizzarri R, Arcangeli C, Arosio D, Ricci F, Faraci P, Cardarelli F, Beltram F. Development of a novel GFP-based ratiometric excitation and emission pH indicator for intracellular studies. Biophys J 2007; 90:3300-14. [PMID: 16603505 PMCID: PMC1432127 DOI: 10.1529/biophysj.105.074708] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report on the development of the F64L/S65T/T203Y/L231H GFP mutant (E2GFP) as an effective ratiometric pH indicator for intracellular studies. E2GFP shows two distinct spectral forms that are convertible upon pH changes both in excitation and in emission with pK close to 7.0. The excitation of the protein at 488 and 458 nm represents the best choice in terms of signal dynamic range and ratiometric deviation from the thermodynamic pK. This makes E2GFP ideally suited for imaging setups equipped with the most widespread light sources and filter settings. We used E2GFP to determine the average intracellular pH (pH(i)) and spatial pH(i) maps in two different cell lines, CHO and U-2 OS, under physiological conditions. In CHO, we monitored the evolution of the pH(i) during mitosis. We also showed the possibility to target specific subcellular compartments such as nucleoli (by fusing E2GFP with the transactivator protein of HIV, (Tat) and nuclear promyelocytic leukemia bodies (by coexpression of promyelocytic leukemia protein).
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25
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Ghukasyan V, Hsu YY, Kung SH, Kao FJ. Application of fluorescence resonance energy transfer resolved by fluorescence lifetime imaging microscopy for the detection of enterovirus 71 infection in cells. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:024016. [PMID: 17477731 DOI: 10.1117/1.2718582] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Timely and effective virus infection detection is critical for the clinical management and prevention of the disease spread in communities during an outbreak. A range of methods have been developed for this purpose, of which classical serological and viral nucleic acids detection are the most popular. We describe an alternative, imaging-based approach that utilizes fluorescence resonance energy transfer (FRET) resolved by fluorescence lifetime imaging microscopy (FLIM) and demonstrate it on the example of enterovirus 71 (EV71) infection detection. A plasmid construct is developed with the sequence for GFP2 and DsRed2 fluorescent proteins, linked by a 12-amino-acid-long cleavage recognition site for the 2A protease (2A(pro)), encoded by the EV71 genome and specific for the members of Picornaviridae family. In the construct expressed in HeLa cells, the linker binds the fluorophores within the Forster distance and creates a condition for FRET to occur, thus resulting in shortening of the GFP2 fluorescence lifetime. On cells infection with EV71, viral 2A(pro) released to the cytoplasm cleaves the recognition site, causing disruption of FRET through separation of the fluorophores. Thus, increased GFP2 lifetime to the native values, manifested by the time-correlated single-photon counting, serves as an efficient and specific indicator of the EV71 virus infection.
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Affiliation(s)
- Vladimir Ghukasyan
- National Yang-Ming University, Institute of Biophotonics Engineering, 155, Li-Nong St., Sec. 2, Taipei 112, Taiwan
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26
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Zhu T, Gobeil F, Vazquez-Tello A, Leduc M, Rihakova L, Bossolasco M, Bkaily G, Peri K, Varma DR, Orvoine R, Chemtob S. Intracrine signaling through lipid mediators and their cognate nuclear G-protein-coupled receptors: a paradigm based on PGE2, PAF, and LPA1 receptors. Can J Physiol Pharmacol 2006; 84:377-91. [PMID: 16902584 DOI: 10.1139/y05-147] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Prostaglandins (PGs), platelet-activating factor (PAF), and lysophosphatidic acid (LPA) are ubiquitous lipid mediators that play important roles in inflammation, cardiovascular homeostasis, and immunity and are also known to modulate gene expression of specific pro-inflammatory genes. The mechanism of action of these lipids is thought to be primarily dependent on their specific plasma membrane receptors belonging to the superfamily of G-protein-coupled receptors (GPCR). Increasing evidence suggests the existence of a functional intracellular GPCR population. It has been proposed that immediate effects are mediated via cell surface receptors whereas long-term responses are dependent upon intracellular receptor effects. Indeed, receptors for PAF, LPA, and PGE(2) (specifically EP(1), EP(3), and EP(4)) localize at the cell nucleus of cerebral microvascular endothelial cells of newborn pigs, rat hepatocytes, and cells overexpressing each receptor. Stimulation of isolated nuclei with these lipids reveals biological functions including transcriptional regulation of major genes, namely c-fos, cylooxygenase-2, and endothelial as well as inducible nitric oxide synthase. In the present review, we shall focus on the nuclear localization and signaling of GPCRs recognizing PGE(2), PAF, and LPA phospholipids as ligands. Mechanisms on how nuclear PGE2, PAF, and LPA receptors activate gene transcription and nuclear localization pathways are presented. Intracrine signaling for lipid mediators uncover novel pathways to elicit their effects; accordingly, intracellular GPCRs constitute a distinctive mode of action for gene regulation.
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Affiliation(s)
- Tang Zhu
- Department of Pediatrics, Research Center of Hôpital Sainte-Justine, Université de Montréal, QC, Canada
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27
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Bkaily G, Nader M, Avedanian L, Choufani S, Jacques D, D'Orléans-Juste P, Gobeil F, Chemtob S, Al-Khoury J. G-protein-coupled receptors, channels, and Na+–H+exchanger in nuclear membranes of heart, hepatic, vascular endothelial, and smooth muscle cellsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell. Can J Physiol Pharmacol 2006; 84:431-41. [PMID: 16902588 DOI: 10.1139/y06-002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The action of several peptides and drugs is thought to be primarily dependent on their interactions with specific cell surface G-protein-coupled receptors and ionic transporters such as channels and exchangers. Recent development of 3-D confocal microscopy allowed several laboratories, including ours, to identify and study the localization of receptors, channels, and exchangers at the transcellular level of several cell types. Using this technique, we demonstrated in the nuclei of several types of cells the presence of Ca2+channels as well as Na+–H+exchanger and receptors such as endothelin-1 and angiotensin II receptors. Stimulation of these nuclear membrane G-protein-coupled receptors induced an increase of nuclear Ca2+. Our results suggest that, similar to the plasma membrane, nuclear membranes possess channels, exchangers and receptors such as those for endothelin-1 and angiotensin II, and that the nucleus seems to be a cell within a cell. This article will emphasize these findings.
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Affiliation(s)
- Ghassan Bkaily
- Department of Anatomy and Cell Biology, Faculty of Medicine, Université de Sherbrooke, QC, Canada.
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28
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Pantazis A, Keegan P, Postma M, Schwiening CJ. The effect of neuronal morphology and membrane-permeant weak acid and base on the dissipation of depolarization-induced pH gradients in snail neurons. Pflugers Arch 2005; 452:175-87. [PMID: 16341877 DOI: 10.1007/s00424-005-0019-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 09/15/2005] [Accepted: 10/26/2005] [Indexed: 10/25/2022]
Abstract
Neuronal depolarization causes larger intracellular pH (pH(i)) shifts in axonal and dendritic regions than in the cell body. In this paper, we present evidence relating the time for collapse of these gradients to neuronal morphology. We have used ratiometric pH(i) measurements using 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) in whole-cell patch-clamped snail neurons to study the collapse of longitudinal pH gradients. Using depolarization to open voltage-gated proton channels, we produced alkaline pH(i) microdomains. In the absence of added mobile buffers, facilitated H(+) diffusion down the length of the axon plays a critical role in determining pH(i) microdomain lifetime, with axons of approximately 100 microm allowing pH differences to be maintained for >60 s. An application of mobile, membrane-permeant pH buffers accelerated the collapse of the alkaline-pH gradients but, even at 30 mM, was unable to abolish them. Modeling of the pH(i) dynamics showed that both the relatively weak effect of the weak acid/base on the peak size of the pH gradient and the accelerated collapse of the pH gradient could be due to the time taken for equilibration of the weak acid and base across the cell. We propose that appropriate weak acid/base mixes may provide a simple method for studying the role of local pH(i) signals without perturbing steady-state pH(i). Furthermore, an extrapolation of our in vitro data to longer and thinner neuronal structures found in the mammalian nervous system suggests that dendritic and axonal pH(i) are likely to be dominated by local pH(i)-regulating mechanisms rather than simply following the soma pH(i).
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Affiliation(s)
- A Pantazis
- Department of Anatomy, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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29
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Marrache AM, Gobeil F, Zhu T, Chemtob S. Intracellular signaling of lipid mediators via cognate nuclear G protein-coupled receptors. ACTA ACUST UNITED AC 2005; 12:63-72. [PMID: 16036317 DOI: 10.1080/10623320590933815] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Platelet-activating factor (PAF) and lysophosphatidic acid (LPA) are ubiquitous lipid mediators that play important roles in inflammation, cardiovascular homeostasis, and immunity and are also known to modulate gene expression of specific proinflammatory genes. The mechanism of action of these phospholipids is thought to be primarily dependent on their specific plasma membrane receptors belonging to the superfamily of G protein-coupled receptors (GPCRs). However, increasing evidence suggests the existence of a functional intracellular GPCR population. It has been suggested that immediate effects are mediated by cell surface receptors, whereas long-term responses are mediated by intracellular receptors. PAF and LPA(1) receptors localize at the cell nucleus of cerebral microvascular endothelial cells of newborn pig, rat hepatocytes, and cells overexpressing each receptor, and stimulation of isolated nuclei reveal biological functions, including transcriptional regulation of major genes, namely cylooxygenase-2 and inducible nitric oxide synthase. This mini review focuses on the nuclear localization and signaling of GPCRs, recognizing PAF and LPA phospholipids as ligands. Theories on how nuclear PAF and LPA1 receptors activate gene transcription and nuclear localization pathways are discussed. Intracrine signaling for lipid mediators uncover novel pathways to elicit their effects; moreover, intracellular GPCRs constitute a distinctive mode of action for gene regulation.
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30
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Quinlan RJ, Reinhart GD. Baroresistant buffer mixtures for biochemical analyses. Anal Biochem 2005; 341:69-76. [PMID: 15866529 DOI: 10.1016/j.ab.2005.03.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Indexed: 11/24/2022]
Abstract
Hydrostatic pressure is a useful tool in the study of varied fields such as protein aggregation, association, folding, ligand binding, and allostery. Application of pressure can have a significant effect on the pK(a) values of buffers commonly used for biochemical analysis. Consequently, cationic buffers, rather than neutral ones, are generally used to minimize pH effects; however, even with these buffers, the change in pH over 3 kbar may be consequential in highly pH-sensitive biochemical systems. Using fluorescence-based assays, we have systematically examined the effects of pressure on various buffers in the neutral pH range. We show that many commonly used cationic and Good's buffers increase in pH with pressure on the order of 0.1 to 0.3 pH units/kbar, in agreement with other published values. Carboxylates and phosphate decrease in pH to a similar extent. Buffer mixtures, composed of both cationic and carboxylate or phosphate components, are shown to be an order of magnitude less pressure sensitive than the individual component buffers. Using various relative concentrations of Tris and either phosphate, tricarballylate (1,2,3-propanetricarboxylate), or CDA (1,1-cyclohexane diacetate) at pH values between 7 and 8 yields baroresistant buffer mixtures. Buffer mixtures can be optimized for a specific pH, and a list of mixtures is presented for general laboratory use.
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Affiliation(s)
- R Jason Quinlan
- Department of Biochemistry and Biophysics, Texas A&M University, Texas Agricultural Experiment Station, 2128 TAMU, College Station, TX 77843, USA
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31
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Liu R, Carretero OA, Ren Y, Garvin JL. Increased intracellular pH at the macula densa activates nNOS during tubuloglomerular feedback. Kidney Int 2005; 67:1837-43. [PMID: 15840031 DOI: 10.1111/j.1523-1755.2005.00282.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The macula densa senses increasing NaCl concentrations in tubular fluid and increases afferent arteriole tone by a process known as tubuloglomerular feedback (TGF). Nitric oxide (NO) production by macula densa neuronal nitric oxide synthase (nNOS) is enhanced by increasing NaCl in the macula densa lumen, and the NO thus formed inhibits TGF. Blocking apical Na(+)/H(+) exchange with amiloride augments TGF and mimics the effect of nNOS inhibition. We hypothesized that increasing NaCl in the macula densa lumen raises macula densa intracellular pH (pH(i)) and activates nNOS. METHODS The thick ascending limb and a portion of the distal tubule with intact macula densa plaque adherent to the glomerulus were microdissected and perfused. Macula densa perfusate was changed from a low (10 mmol/L) to high NaCl solution (80 mmol/L) to mimic the conditions that induce TGF. Osmolality of both solutions was 180 mOsm, so that changing the solutions did not alter cell volume. RESULTS Macula densa pH(i) increased significantly from 7.0 +/- 0.5 to 7.8 +/- 0.6 when the perfusate was changed from low to high (P < 0.05; N= 5). When amiloride was added to inhibit Na(+)/H(+) exchange, the increase in pH(i) during TGF was blocked (N= 5). Fluorescence intensity of DAF-2, an NO-sensitive dye, increased by 28.8 +/- 4.1% after increasing luminal NaCl (N= 5), indicating an increase in NO production. In the presence of the Na(+)/H(+) exchanger inhibitor amiloride or the nNOS inhibitor 7-NI, the increase in NO induced by switching the macula densa perfusate from low to high was blunted. To study whether changes in pH(i) can directly alter NO production, we used nigericin, a K(+)/H(+) ionophore, to equilibrate luminal and intracellular pH. When macula densa pH was raised from 7.3 to 7.8 in the presence of 10(-5) mol/L nigericin in the low NaCl solution, fluorescence of DAF-2 in the macula densa increased by 17.9 +/- 1.3% (P < 0.01; N= 5). In the presence of 7-NI, the increase in NO induced by raising pH(i) was blocked (N= 5). CONCLUSION We concluded that macula densa pH(i) increases during TGF, and this increase in pH(i) activates nNos.
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Affiliation(s)
- Ruisheng Liu
- Hypertension & Vascular Research Division, Henry Ford Hospital, Detroit, Michigan 48202, USA.
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Asokan A, Cho MJ. Exploitation of intracellular pH gradients in the cellular delivery of macromolecules. J Pharm Sci 2002; 91:903-13. [PMID: 11948528 DOI: 10.1002/jps.10095] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Most cellular components such as the cytoplasm, endosomes, lysosomes, endoplasmic reticulum, Golgi bodies, mitochondria, and nuclei are known to maintain their own characteristic pH values. These pH values range from as low as 4.5 in the lysosome to about 8.0 in the mitochondria. Given these proton gradients around a neutral pH, weak acids, and bases with a pKa between 5.0 and 8.0 can exhibit dramatic changes in physicochemical properties. These compounds can be conjugated as such to macromolecules or incorporated into polymeric or liposomal formulations to promote the efficient cellular delivery of macromolecules. Mechanistically, the carrier molecules can facilitate favorable membrane partition, membrane fusion, transient pore formation, or membrane disruption. Drug carriers equipped with such pH-sensitive triggers and switches are able to significantly enhance the cellular delivery of macromolecules in vitro. However, the successful application of these molecules for efficient delivery in vivo requires the design of noncytotoxic, nonimmunogenic, serum compatible and biochemically labile carriers, systematic analysis of their mechanisms of action, and extensive animal studies.
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Affiliation(s)
- Aravind Asokan
- Division of Drug Delivery & Disposition, CB # 7360, School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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33
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Osmotic regulation of DNA activity and the cell cycle. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1568-1254(00)80014-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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