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Alwetaid MY, Almanaa TN, Bakheet SA, Ansari MA, Nadeem A, Attia SM, Hussein MH, Attia MSM, Ahmad SF. Aflatoxin B 1 exposure exacerbates chemokine receptor expression in the BTBR T + Itpr3 tf/J Mouse Model, unveiling insights into autism spectrum disorder: A focus on brain and spleen. Reprod Toxicol 2024; 126:108599. [PMID: 38679149 DOI: 10.1016/j.reprotox.2024.108599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Revised: 04/16/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
OBJECTIVE Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by significant difficulties in social interaction, communication, and repeated stereotypic behaviour. Aflatoxin B1 (AFB1) is the most potent and well-known mycotoxin in various food sources. Despite its propensity to generate significant biochemical and structural changes in human and animal tissues, the influence of AFB1 on ASD has yet to be thoroughly studied. Mounting evidence indicates that chemokine receptors play a crucial function in the central nervous system and are implicated in developing several neuroinflammatory disorders. Chemokine receptors in individuals with ASD were elevated in the anterior cingulate gyrus astrocytes, cerebellum, and brain. METHODS The BTBR T+Itpr3tf/J (BTBR) mice are inbred strains that exhibit strong and consistently observed deficits in social interactions, characterized by excessive self-grooming and limited vocalization in social contexts. We examined the impact of AFB1 on CCR3-, CCR7-, CCR9-, CXCR3-, CXCR4-, and CXCR6-expressing I-A/I-E+ cells in the spleen of the BTBR mouse model of autism. We evaluated the mRNA levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 chemokine receptors in the brain. RESULTS The exposure to AFB1 in BTBR mice resulted in a significant rise in the number of I-A/I-E+CCR3+, I-A/I-E+CCR7+, I-A/I-E+CCR9+, I-A/I-E+CXCR3+, I-A/I-E+CXCR4+, and I-A/I-E+CXCR6+ cells. Furthermore, exposure to AFB1 increased mRNA expression levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 in the brain. CONCLUSIONS These findings highlight that AFB1 exposure increases the expression of chemokine receptors in BTBR mice, indicating the necessity for further research into AFB1's role in the development of ASD.
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Affiliation(s)
- Mohammad Y Alwetaid
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Taghreed N Almanaa
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
| | - Saleh A Bakheet
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mushtaq A Ansari
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Ahmed Nadeem
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Sabry M Attia
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Marwa H Hussein
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mohamed S M Attia
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Sheikh F Ahmad
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia.
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2
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Li L, Xin J, Wang H, Wang Y, Peng W, Sun N, Huang H, Zhou Y, Liu X, Lin Y, Fang J, Jing B, Pan K, Zeng Y, Zeng D, Qin X, Bai Y, Ni X. Fluoride disrupts intestinal epithelial tight junction integrity through intracellular calcium-mediated RhoA/ROCK signaling and myosin light chain kinase. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 257:114940. [PMID: 37099960 DOI: 10.1016/j.ecoenv.2023.114940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/12/2023] [Accepted: 04/18/2023] [Indexed: 05/08/2023]
Abstract
Fluoride is a common contaminant of groundwater and agricultural commodity, which poses challenges to animal and human health. A wealth of research has demonstrated its detrimental effects on intestinal mucosal integrity; however, the underlying mechanisms remain obscure. This study aimed to investigate the role of the cytoskeleton in fluoride-induced barrier dysfunction. After sodium fluoride (NaF) treatment of the cultured Caco-2 cells, both cytotoxicity and cytomorphological changes (internal vacuoles or massive ablation) were observed. NaF lowered transepithelial electrical resistance (TEER) and enhanced paracellular permeation of fluorescein isothiocyanate dextran 4 (FD-4), indicating Caco-2 monolayers hyperpermeability. In the meantime, NaF treatment altered both the expression and distribution of the tight junction protein ZO-1. Fluoride exposure increased myosin light chain II (MLC2) phosphorylation and triggered actin filament (F-actin) remodeling. While inhibition of myosin II by Blebbistatin blocked NaF-induced barrier failure and ZO-1 discontinuity, the corresponding agonist Ionomycin had effects comparable to those of fluoride, suggesting that MLC2 serves as an effector. Given the mechanisms upstream of p-MLC2 regulation, further studies demonstrated that NaF activated RhoA/ROCK signaling pathway and myosin light chain kinase (MLCK), strikingly increasing the expression of both. Pharmacological inhibitors (Rhosin, Y-27632 and ML-7) reversed NaF-induced barrier breakdown and stress fiber formation. The role of intracellular calcium ions ([Ca2+]i) in NaF effects on Rho/ROCK pathway and MLCK was investigated. We found that NaF elevated [Ca2+]i, whereas chelator BAPTA-AM attenuated increased RhoA and MLCK expression as well as ZO-1 rupture, thus, restoring barrier function. Collectively, abovementioned results suggest that NaF induces barrier impairment via Ca2+-dependent RhoA/ROCK pathway and MLCK, which in turn triggers MLC2 phosphorylation and rearrangement of ZO-1 and F-actin. These results provide potential therapeutic targets for fluoride-induced intestinal injury.
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Affiliation(s)
- Lianxin Li
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Jinge Xin
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Hesong Wang
- Baiyun Branch, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yadong Wang
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology of Guangdong Province, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Weiqi Peng
- Baiyun Branch, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Ning Sun
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Haonan Huang
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yanxi Zhou
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Xingmei Liu
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yu Lin
- Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology of Guangdong Province, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jing Fang
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Bo Jing
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Kangcheng Pan
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Yan Zeng
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Dong Zeng
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Xiang Qin
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, China.
| | - Yang Bai
- Baiyun Branch, Nanfang Hospital, Southern Medical University, Guangzhou, China; Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Institute of Gastroenterology of Guangdong Province, Nanfang Hospital, Southern Medical University, Guangzhou, China.
| | - Xueqin Ni
- Animal Microecology Institute, College of Veterinary, Sichuan Agricultural University, Chengdu, Sichuan, China.
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3
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Zhao MJ, Jiang HR, Sun JW, Wang ZA, Hu B, Zhu CR, Yin XH, Chen MM, Ma XC, Zhao WD, Luan ZG. Roles of RAGE/ROCK1 Pathway in HMGB1-Induced Early Changes in Barrier Permeability of Human Pulmonary Microvascular Endothelial Cell. Front Immunol 2021; 12:697071. [PMID: 34745088 PMCID: PMC8564108 DOI: 10.3389/fimmu.2021.697071] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 10/01/2021] [Indexed: 01/21/2023] Open
Abstract
Background High mobility group box 1 (HMGB1) causes microvascular endothelial cell barrier dysfunction during acute lung injury (ALI) in sepsis, but the mechanisms have not been well understood. We studied the roles of RAGE and Rho kinase 1 (ROCK1) in HMGB1-induced human pulmonary endothelial barrier disruption. Methods In the present study, the recombinant human high mobility group box 1 (rhHMGB1) was used to stimulate human pulmonary microvascular endothelial cells (HPMECs). The endothelial cell (EC) barrier permeability was examined by detecting FITC-dextran flux. CCK-8 assay was used to detect cell viability under rhHMGB1 treatments. The expression of related molecules involved in RhoA/ROCK1 pathway, phosphorylation of myosin light chain (MLC), F-actin, VE-cadherin and ZO-1 of different treated groups were measured by pull-down assay, western blot and immunofluorescence. Furthermore, we studied the effects of Rho kinase inhibitor (Y-27632), ROCK1/2 siRNA, RAGE-specific blocker (FPS-ZM1) and RAGE siRNA on endothelial barrier properties to elucidate the related mechanisms. Results In the present study, we demonstrated that rhHMGB1 induced EC barrier hyperpermeability in a dose-dependent and time-dependent manner by measuring FITC-dextran flux, a reflection of the loss of EC barrier integrity. Moreover, rhHMGB1 induced a dose-dependent and time-dependent increases in paracellular gap formation accompanied by the development of stress fiber rearrangement and disruption of VE-cadherin and ZO-1, a phenotypic change related to increased endothelial contractility and endothelial barrier permeability. Using inhibitors and siRNAs directed against RAGE and ROCK1/2, we systematically determined that RAGE mediated the rhHMGB1-induced stress fiber reorganization via RhoA/ROCK1 signaling activation and the subsequent MLC phosphorylation in ECs. Conclusion HMGB1 is capable of disrupting the endothelial barrier integrity. This study demonstrates that HMGB1 activates RhoA/ROCK1 pathway via RAGE, which phosphorylates MLC inducing stress fiber formation at short time, and HMGB1/RAGE reduces AJ/TJ expression at long term independently of RhoA/ROCK1 signaling pathway.
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Affiliation(s)
- Meng-Jiao Zhao
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Hao-Ran Jiang
- Department of Breast Oncology, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Jing-Wen Sun
- Department of Developmental Cell Biology, Key Laboratory of Cell Biology, Ministry of Public Health, and Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, China
| | - Zi-Ang Wang
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Bo Hu
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Cheng-Rui Zhu
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Xiao-Han Yin
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Ming-Ming Chen
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Xiao-Chun Ma
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
| | - Wei-Dong Zhao
- Department of Developmental Cell Biology, Key Laboratory of Cell Biology, Ministry of Public Health, and Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University, Shenyang, China
| | - Zheng-Gang Luan
- Department of Critical Care Medicine, The First Affiliated Hospital of China Medical University, Shenyang, China
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Chua XY, Mensah T, Aballo T, Mackintosh SG, Edmondson RD, Salomon AR. Tandem Mass Tag Approach Utilizing Pervanadate BOOST Channels Delivers Deeper Quantitative Characterization of the Tyrosine Phosphoproteome. Mol Cell Proteomics 2020; 19:730-743. [PMID: 32071147 PMCID: PMC7124467 DOI: 10.1074/mcp.tir119.001865] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 02/07/2020] [Indexed: 01/08/2023] Open
Abstract
Dynamic tyrosine phosphorylation is fundamental to a myriad of cellular processes. However, the inherently low abundance of tyrosine phosphorylation in the proteome and the inefficient enrichment of phosphotyrosine(pTyr)-containing peptides has led to poor pTyr peptide identification and quantitation, critically hindering researchers' ability to elucidate signaling pathways regulated by tyrosine phosphorylation in systems where cellular material is limited. The most popular approaches to wide-scale characterization of the tyrosine phosphoproteome use pTyr enrichment with pan-specific, anti-pTyr antibodies from a large amount of starting material. Methods that decrease the amount of starting material and increase the characterization depth of the tyrosine phosphoproteome while maintaining quantitative accuracy and precision would enable the discovery of tyrosine phosphorylation networks in rarer cell populations. To achieve these goals, the BOOST (Broad-spectrum Optimization Of Selective Triggering) method leveraging the multiplexing capability of tandem mass tags (TMT) and the use of pervanadate (PV) boost channels (cells treated with the broad-spectrum tyrosine phosphatase inhibitor PV) selectively increased the relative abundance of pTyr-containing peptides. After PV boost channels facilitated selective fragmentation of pTyr-containing peptides, TMT reporter ions delivered accurate quantitation of each peptide for the experimental samples while the quantitation from PV boost channels was ignored. This method yielded up to 6.3-fold boost in pTyr quantification depth of statistically significant data derived from contrived ratios, compared with TMT without PV boost channels or intensity-based label-free (LF) quantitation while maintaining quantitative accuracy and precision, allowing quantitation of over 2300 unique pTyr peptides from only 1 mg of T cell receptor-stimulated Jurkat T cells. The BOOST strategy can potentially be applied in analyses of other post-translational modifications where treatments that broadly elevate the levels of those modifications across the proteome are available.
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Affiliation(s)
- Xien Yu Chua
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island
| | - Theresa Mensah
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - Timothy Aballo
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - Samuel G Mackintosh
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Ricky D Edmondson
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Arthur R Salomon
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island.
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5
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MLCK and ROCK mutualism in endothelial barrier dysfunction. Biochimie 2020; 168:83-91. [DOI: 10.1016/j.biochi.2019.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/22/2019] [Indexed: 01/15/2023]
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6
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Johnston NR, Strobel SA. Nitrate and Phosphate Transporters Rescue Fluoride Toxicity in Yeast. Chem Res Toxicol 2019; 32:2305-2319. [PMID: 31576749 DOI: 10.1021/acs.chemrestox.9b00315] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Organisms are exposed to fluoride in the air, water, and soil. Yeast and other microbes utilize fluoride channels as a method to prevent intracellular fluoride accumulation and mediate fluoride toxicity. Consequently, deletion of fluoride exporter genes (FEX) in S. cerevisiae resulted in over 1000-fold increased fluoride sensitivity. We used this FEX knockout strain to identify genes, that when overexpressed, are able to partially relieve the toxicity of fluoride exposure. Overexpression of five genes, SSU1, YHB1, IPP1, PHO87, and PHO90, increase fluoride tolerance by 2- to 10-fold. Overexpression of these genes did not provide improved fluoride resistance in wild-type yeast, suggesting that the mechanism is specific to low fluoride toxicity in yeast. Ssu1p and Yhb1p both function in nitrosative stress response, which is induced upon fluoride exposure along with metal influx. Ipp1p, Pho87p, and Pho90p increase intracellular orthophosphate. Consistent with this observation, fluoride toxicity is also partially mitigated by the addition of high levels of phosphate to the growth media. Fluoride inhibits phosphate import upon stress induction and causes nutrient starvation and organelle disruption, as supported by gene induction monitored through RNA-Seq. The combination of observations suggests that transmembrane nutrient transporters are among the most sensitized proteins during fluoride-instigated stress.
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Affiliation(s)
- Nichole R Johnston
- From the Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06520
| | - Scott A Strobel
- From the Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06520.,Department of Chemistry , Yale University , New Haven , Connecticut 06520
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7
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Barros Ribeiro da Silva V, Porcionatto M, Toledo Ribas V. The Rise of Molecules Able To Regenerate the Central Nervous System. J Med Chem 2019; 63:490-511. [PMID: 31518122 DOI: 10.1021/acs.jmedchem.9b00863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Injury to the adult central nervous system (CNS) usually leads to permanent deficits of cognitive, sensory, and/or motor functions. The failure of axonal regeneration in the damaged CNS limits functional recovery. The lack of information concerning the biological mechanism of axonal regeneration and its complexity has delayed the process of drug discovery for many years compared to other drug classes. Starting in the early 2000s, the ability of many molecules to stimulate axonal regrowth was evaluated through automated screening techniques; many hits and some new mechanisms involved in axonal regeneration were identified. In this Perspective, we discuss the rise of the CNS regenerative drugs, the main biological techniques used to test these drug candidates, some of the most important screens performed so far, and the main challenges following the identification of a drug that is able to induce axonal regeneration in vivo.
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Affiliation(s)
| | - Marimélia Porcionatto
- Universidade Federal de São Paulo , Escola Paulista de Medicina, Laboratório de Neurobiologia Molecular, Departmento de Bioquímica , Rua Pedro de Toledo, 669 - third floor, 04039-032 São Paulo , São Paolo , Brazil
| | - Vinicius Toledo Ribas
- Universidade Federal de Minas Gerais , Instituto de Ciências Biológicas, Departamento de Morfologia, Laboratório de Neurobiologia Av. Antônio Carlos, 6627, room O3-245 , - Campus Pampulha, 31270-901 , Belo Horizonte , Minas Gerais , Brazil
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8
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A unified in vitro test system for the assessment of tight junction modulators. Eur J Pharm Biopharm 2019; 142:353-363. [DOI: 10.1016/j.ejpb.2019.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 06/28/2019] [Accepted: 07/02/2019] [Indexed: 11/23/2022]
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9
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In Vivo Comparison of the Phenotypic Aspects and Molecular Mechanisms of Two Nephrotoxic Agents, Sodium Fluoride and Uranyl Nitrate. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16071136. [PMID: 30934888 PMCID: PMC6479911 DOI: 10.3390/ijerph16071136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 03/22/2019] [Accepted: 03/26/2019] [Indexed: 02/03/2023]
Abstract
Because of their nephrotoxicity and presence in the environment, uranium (U) and fluoride (F) represent risks to the global population. There is a general lack of knowledge regarding the mechanisms of U and F nephrotoxicity and the underlying molecular pathways. The present study aims to compare the threshold of the appearance of renal impairment and to study apoptosis and inflammation as mechanisms of nephrotoxicity. C57BL/6J male mice were intraperitoneally treated with a single dose of U (0, 2, 4 and 5 mg/kg) or F (0, 2, 5, 7.5 and 10 mg/kg) and euthanized 72 h after. Renal phenotypic characteristics and biological mechanisms were evaluated by urine biochemistry, gene/protein expression, enzyme activity, and (immuno)histological analyses. U and F exposures induced nephrotoxicity in a dose-dependent manner, and the highest concentrations induced severe histopathological alterations as well as increased gene expression and urinary excretion of nephrotoxicity biomarkers. KIM-1 gene expression was induced starting at 2 mg/kg U and 7.5 mg/kg F, and this increase in expression was confirmed through in situ detection of this biomarker of nephrotoxicity. Both treatments induced inflammation as evidenced by cell adhesion molecule expression and in situ levels, whereas caspase 3/7-dependent apoptosis was increased only after U treatment. Overall, a single dose of F or U induced histopathologic evidence of nephrotoxicity renal impairment and inflammation in mice with thresholds under 7.5 mg/kg and 4 mg/kg, respectively.
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10
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Shashkova S, Wollman AJM, Leake MC, Hohmann S. The yeast Mig1 transcriptional repressor is dephosphorylated by glucose-dependent and -independent mechanisms. FEMS Microbiol Lett 2018; 364:3884263. [PMID: 28854669 DOI: 10.1093/femsle/fnx133] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 06/21/2017] [Indexed: 12/28/2022] Open
Abstract
A yeast Saccharomyces cerevisiae Snf1 kinase, an analog of mammalian AMPK, regulates glucose derepression of genes required for utilization of alternative carbon sources through the transcriptional repressor Mig1. It has been suggested that the Glc7-Reg1 phosphatase dephosphorylates Mig1. Here we report that Mig1 is dephosphorylated by Glc7-Reg1 in an apparently glucose-dependent mechanism but also by a mechanism independent of glucose and Glc7-Reg1. In addition to serine/threonine phosphatases another process including tyrosine phosphorylation seems crucial for Mig1 regulation. Taken together, Mig1 dephosphorylation appears to be controlled in a complex manner, in line with the importance for rapid and sensitive regulation upon altered glucose concentrations in the growth medium.
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Affiliation(s)
- Sviatlana Shashkova
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Göteborg, Sweden.,Biological Physical Sciences Institute, University of York, York YO10 5DD, UK
| | - Adam J M Wollman
- Biological Physical Sciences Institute, University of York, York YO10 5DD, UK
| | - Mark C Leake
- Biological Physical Sciences Institute, University of York, York YO10 5DD, UK
| | - Stefan Hohmann
- Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Göteborg, Sweden.,Department of Biology and Biological Engineering, Chalmers University of Technology, 41296 Göteborg, Sweden
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11
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Amadeu de Oliveira F, MacVinish LJ, Amin S, Herath D, Jeggle P, Mela I, Pieri M, Sharma C, Jarvis GE, Levy FM, Santesso MR, Khan ZN, Leite AL, Oliveira RC, Buzalaf MAR, Edwardson JM. The effect of fluoride on the structure, function, and proteome of intestinal epithelia. ENVIRONMENTAL TOXICOLOGY 2018; 33:63-71. [PMID: 29068160 DOI: 10.1002/tox.22495] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/06/2017] [Accepted: 10/06/2017] [Indexed: 06/07/2023]
Abstract
Fluoride exposure is widespread, with drinking water commonly containing natural and artificially added sources of the ion. Ingested fluoride undergoes absorption across the gastric and intestinal epithelia. Previous studies have reported adverse gastrointestinal effects with high levels of fluoride exposure. Here, we examined the effects of fluoride on the transepithelial ion transport and resistance of three intestinal epithelia. We used the Caco-2 cell line as a model of human intestinal epithelium, and rat and mouse colonic epithelia for purposes of comparison. Fluoride caused a concentration-dependent decline in forskolin-induced Cl- secretion and transepithelial resistance of Caco-2 cell monolayers, with an IC50 for fluoride of about 3 mM for both parameters. In the presence of 5 mM fluoride, transepithelial resistance fell exponentially with time, with a t1/2 of about 7 hours. Subsequent imaging by immunofluorescence and scanning electron microscopy showed structural abnormalities in Caco-2 cell monolayers exposed to fluoride. The Young's modulus of the epithelium was not affected by fluoride, although proteomic analysis revealed changes in expression of a number of proteins, particularly those involved in cell-cell adhesion. In line with its effects on Caco-2 cell monolayers, fluoride, at 5 mM, also had profound effects on Cl- secretion and transepithelial resistance of both rat and mouse colonic epithelia. Our results show that treatment with fluoride has major effects on the structure, function, and proteome of intestinal epithelia, but only at concentrations considerably higher than those likely to be encountered in vivo, when much lower fluoride doses are normally ingested on a chronic basis.
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Affiliation(s)
- Flávia Amadeu de Oliveira
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Lesley J MacVinish
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Simran Amin
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Duleni Herath
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Pia Jeggle
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Ioanna Mela
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Maria Pieri
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Chetanya Sharma
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Gavin E Jarvis
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Flávia M Levy
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Mariana R Santesso
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Zohaib N Khan
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Aline L Leite
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Rodrigo C Oliveira
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - Marília A R Buzalaf
- Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil
| | - J Michael Edwardson
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
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12
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Mascarenhas JB, Tchourbanov AY, Fan H, Danilov SM, Wang T, Garcia JGN. Mechanical Stress and Single Nucleotide Variants Regulate Alternative Splicing of the MYLK Gene. Am J Respir Cell Mol Biol 2017; 56:29-37. [PMID: 27529643 DOI: 10.1165/rcmb.2016-0053oc] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The nonmuscle (nm) myosin light-chain kinase isoform (MLCK), encoded by the MYLK gene, is a vital participant in regulating vascular barrier responses to mechanical and inflammatory stimuli. We determined that MYLK is alternatively spliced, yielding functionally distinct nmMLCK splice variants including nmMLCK2, a splice variant highly expressed in vascular endothelial cells (EC) and associated with reduced EC barrier integrity. We demonstrated previously that the nmMLCK2 variant lacks exon 11, which encodes a key regulatory region containing two differentially phosphorylated tyrosine residues (Y464 and Y471) that influence vascular barrier function during inflammation. In this study, we used minigene constructs and RT-PCR to interrogate biophysical factors (mechanical stress) and genetic variants (MYLK single-nucleotide polymorphisms [SNPs]) that are potentially involved in regulating MYLK alternative splicing and nmMLCK2 generation. Human lung EC exposed to pathologic mechanical stress (18% cyclic stretch) produced increased nmMLCK2 expression relative to levels of nmMLCK1 with alternative splicing significantly influenced by MYLK SNPs rs77323602 and rs147245669. In silico analyses predicted that these variants would alter exon 11 donor and acceptor sites for alternative splicing, computational predictions that were confirmed by minigene studies. The introduction of rs77323602 favored wild-type nmMLCK expression, whereas rs147245669 favored alternative splicing and deletion of exon 11, yielding increased nmMLCK2 expression. Finally, lymphoblastoid cell lines selectively harboring these MYLK SNPs (rs77323602 and rs147245669) directly validated SNP-specific effects on MYLK alternative splicing and nmMLCK2 generation. Together, these studies demonstrate that mechanical stress and MYLK SNPs regulate MYLK alternative splicing and generation of a splice variant, nmMLCK2, that contributes to the severity of inflammatory injury.
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Affiliation(s)
| | - Alex Y Tchourbanov
- 2 Arizona Research Laboratory, University of Arizona, Tucson, Arizona; and
| | - Hanli Fan
- 3 Department of Anesthesiology, University of Illinois at Chicago, Chicago, Illinois
| | - Sergei M Danilov
- 1 Department of Medicine, and.,3 Department of Anesthesiology, University of Illinois at Chicago, Chicago, Illinois
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Assessment of Methods for the Intracellular Blockade of GABAA Receptors. PLoS One 2016; 11:e0160900. [PMID: 27501143 PMCID: PMC4976935 DOI: 10.1371/journal.pone.0160900] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/26/2016] [Indexed: 12/11/2022] Open
Abstract
Selective blockade of inhibitory synaptic transmission onto specific neurons is a useful tool for dissecting the excitatory and inhibitory synaptic components of ongoing network activity. To achieve this, intracellular recording with a patch solution capable of blocking GABAA receptors has advantages over other manipulations, such as pharmacological application of GABAergic antagonists or optogenetic inhibition of populations of interneurones, in that the majority of inhibitory transmission is unaffected and hence the remaining network activity preserved. Here, we assess three previously described methods to block inhibition: intracellular application of the molecules picrotoxin, 4,4’-dinitro-stilbene-2,2’-disulphonic acid (DNDS) and 4,4’-diisothiocyanostilbene-2,2’-disulphonic acid (DIDS). DNDS and picrotoxin were both found to be ineffective at blocking evoked, monosynaptic inhibitory postsynaptic currents (IPSCs) onto mouse CA1 pyramidal cells. An intracellular solution containing DIDS and caesium fluoride, but lacking nucleotides ATP and GTP, was effective at decreasing the amplitude of IPSCs. However, this effect was found to be independent of DIDS, and the absence of intracellular nucleotides, and was instead due to the presence of fluoride ions in this intracellular solution, which also blocked spontaneously occurring IPSCs during hippocampal sharp waves. Critically, intracellular fluoride ions also caused a decrease in both spontaneous and evoked excitatory synaptic currents and precluded the inclusion of nucleotides in the intracellular solution. Therefore, of the methods tested, only fluoride ions were effective for intracellular blockade of IPSCs but this approach has additional cellular effects reducing its selectivity and utility.
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Lee J, Han YE, Favorov O, Tommerdahl M, Whitsel B, Lee CJ. Fluoride Induces a Volume Reduction in CA1 Hippocampal Slices Via MAP Kinase Pathway Through Volume Regulated Anion Channels. Exp Neurobiol 2016; 25:72-8. [PMID: 27122993 PMCID: PMC4844565 DOI: 10.5607/en.2016.25.2.72] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 04/04/2016] [Accepted: 04/05/2016] [Indexed: 01/24/2023] Open
Abstract
Regulation of cell volume is an important aspect of cellular homeostasis during neural activity. This volume regulation is thought to be mediated by activation of specific transporters, aquaporin, and volume regulated anion channels (VRAC). In cultured astrocytes, it was reported that swelling-induced mitogen-activated protein (MAP) kinase activation is required to open VRAC, which are thought to be important in regulatory volume decrease and in the response of CNS to trauma and excitotoxicity. It has been also described that sodium fluoride (NaF), a recognized G-protein activator and protein phosphatase inhibitor, leads to a significant MAP kinase activation in endothelial cells. However, NaF's effect in volume regulation in the brain is not known yet. Here, we investigated the mechanism of NaF-induced volume change in rat and mouse hippocampal slices using intrinsic optical signal (IOS) recording, in which we measured relative changes in intracellular and extracellular volume as changes in light transmittance through brain slices. We found that NaF (1~5 mM) application induced a reduction in light transmittance (decreased volume) in CA1 hippocampus, which was completely reversed by MAP kinase inhibitor U0126 (10 µM). We also observed that NaF-induced volume reduction was blocked by anion channel blockers, suggesting that NaF-induced volume reduction could be mediated by VRAC. Overall, our results propose a novel molecular mechanism of NaF-induced volume reduction via MAP kinase signaling pathway by activation of VRAC.
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Affiliation(s)
- Jaekwang Lee
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Young-Eun Han
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Neuroscience Program, University of Science and Technology (UST), Daejeon 34113, Korea
| | - Oleg Favorov
- Departments of Biomedical Engineering, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA
| | - Mark Tommerdahl
- Departments of Biomedical Engineering, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA
| | - Barry Whitsel
- Departments of Biomedical Engineering, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA.; Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, CB#7575, Chapel Hill, NC, USA
| | - C Justin Lee
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Neuroscience Program, University of Science and Technology (UST), Daejeon 34113, Korea
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Sali N, Nagy S, Poór M, Kőszegi T. Multiparametric luminescent cell viability assay in toxicology models: A critical evaluation. J Pharmacol Toxicol Methods 2016; 79:45-54. [PMID: 26777595 DOI: 10.1016/j.vascn.2016.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Revised: 01/08/2016] [Accepted: 01/13/2016] [Indexed: 10/22/2022]
Abstract
INTRODUCTION In cellular viability assays the sole determination of a single parameter might not give precise information on the extent of toxicity. In our study we worked out a multiparametric microplate assay based on bioluminescent ATP quantification, esterase activity-related fluorescence, nucleic acid staining and total intracellular protein measurement from the same sample in MDCK and HepG2 tissue cultures. METHODS Dose-response analyses were done after ATP depletion by metabolic poisons (NaF, NaN3) and by ochratoxin A (OTA) mycotoxin treatments. A novel perchloric acid fixation/extraction technique was applied in order to obtain intracellular ATP levels, esterase activity, DNA content and protein data simultaneously. Esterase activity was assessed by a fluorogenic staining. Estimation of cell number was done by DAPI fluorescence. Our results were expressed as ATP/protein, calcein fluorescence/ATP, calcein fluorescence/protein and ATP/DAPI ratios. Apoptosis/necrosis rates were measured by Annexin V-propidium iodide and 7-aminoactinomycin D flow cytometric assays and effects of OTA on actin cytoskeleton were also studied by using labeled phalloidin for visualization of actin. RESULTS We could verify that the esterase assay was not an energy driven (true viability) process. ATP/protein, calcein fluorescence/ATP, calcein fluorescence/protein ratios, DAPI fluorescence and protein levels together with morphological and apoptosis/necrosis parameters deciphered subtle changes in cell viability with good between-run precision. Dose dependent loss in cell number and decreased protein levels were observed in all cases, while disorganization of actin microfilaments was seen in OTA treated cells. The two cell lines did not respond uniformly to the same treatments. DISCUSSION ATP/protein ratio proved to be a useful viability parameter however, the suppression and/or loss of intracellular protein could cause difficulty in interpreting ATP/protein data. We conclude that correct assessment of cellular viability should be done by measuring multiple parameters related to the specific mode of action of the tested toxic compound.
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Affiliation(s)
- Nikolett Sali
- Department of Laboratory Medicine, University of Pécs, H-7624 Pécs, Ifjuság u. 13., Hungary.
| | - Sándor Nagy
- Institute of Pharmaceutical Technology and Biopharmacy, University of Pécs, H-7624 Pécs, Rókus u. 2., Hungary.
| | - Miklós Poór
- Department of Laboratory Medicine, University of Pécs, H-7624 Pécs, Ifjuság u. 13., Hungary.
| | - Tamás Kőszegi
- Department of Laboratory Medicine, University of Pécs, H-7624 Pécs, Ifjuság u. 13., Hungary; János Szentágothai Research Center, H-7624 Pécs, Ifjuság u. 20., Hungary; Melius Foundation, H-7691 Pécs, Mázsaház u. 24., Hungary.
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Bahey NG, Elaziz HOA, Gadalla KKES. Toxic effect of aflatoxin B1 and the role of recovery on the rat cerebral cortex and hippocampus. Tissue Cell 2015; 47:559-66. [DOI: 10.1016/j.tice.2015.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/20/2015] [Accepted: 09/05/2015] [Indexed: 12/30/2022]
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Zhang J, Yang GM, Zhu Y, Peng XY, Li T, Liu LM. Role of connexin 43 in vascular hyperpermeability and relationship to Rock1-MLC20 pathway in septic rats. Am J Physiol Lung Cell Mol Physiol 2015; 309:L1323-32. [PMID: 26342084 DOI: 10.1152/ajplung.00016.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 08/31/2015] [Indexed: 12/27/2022] Open
Abstract
Connexin (Cx)43 has been shown to participate in several cardiovascular diseases. Increased vascular permeability is a common and severe complication in sepsis or septic shock. Whether or not Cx43 takes part in the regulation of vascular permeability in severe sepsis is not known, and the underlying mechanism has not been described. With cecal ligation and puncture-induced sepsis in rats and lipopolysaccharide (LPS)-treated vascular endothelial cells (VECs) from pulmonary veins, the role of Cx43 in increased vascular permeability and its relationship to the RhoA/Rock1 pathway were studied. It was shown that vascular permeability in the lungs, kidneys, and mesentery in sepsis rats and LPS-stimulated monolayer pulmonary vein VECs was significantly increased and positively correlated with the increased expression of Cx43 and Rock1 in these organs and cultured pulmonary vein VECs. The connexin inhibitor carbenoxolone (10 mg/kg iv) and the Rock1 inhibitor Y-27632 (2 mg/kg iv) alleviated the vascular leakage of lung, mesentery, and kidney in sepsis rats. Overexpressed Cx43 increased the phosphorylation of 20-kDa myosin light chain (MLC20) and the expression of Rock1 and increased the vascular permeability and decreased the transendothelial electrical resistance of pulmonary vein VECs. Cx43 RNA interference decreased the phosphorylation of MLC20 and the expression of Rock1 and decreased LPS-stimulated hyperpermeability of cultured pulmonary vein VECs. The Rock1 inhibitor Y-27632 alleviated LPS- and overexpressed Cx43-induced hyperpermeability of monolayer pulmonary vein VECs. This report shows that Cx43 participates in the regulation of vascular permeability in sepsis and that the mechanism is related to the Rock1-MLC20 phosphorylation pathway.
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Affiliation(s)
- Jie Zhang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Second Department of Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Guang-Ming Yang
- State Key Laboratory of Trauma, Burns, and Combined Injury, Second Department of Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Yu Zhu
- State Key Laboratory of Trauma, Burns, and Combined Injury, Second Department of Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Xiao-Yong Peng
- State Key Laboratory of Trauma, Burns, and Combined Injury, Second Department of Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Tao Li
- State Key Laboratory of Trauma, Burns, and Combined Injury, Second Department of Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Liang-Ming Liu
- State Key Laboratory of Trauma, Burns, and Combined Injury, Second Department of Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, People's Republic of China
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Histological and immunohistochemical study on the effect of aflatoxin B1 on the left ventricular muscle of adult male rabbit with reference to the protective role of melatonin. ACTA ACUST UNITED AC 2014. [DOI: 10.1097/01.ehx.0000455682.80650.e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Biochemical Characterization of an Acid Phosphatase fromThermus thermophilus. Biosci Biotechnol Biochem 2014; 74:727-35. [DOI: 10.1271/bbb.90773] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Al-Ali H, Schürer SC, Lemmon VP, Bixby JL. Chemical interrogation of the neuronal kinome using a primary cell-based screening assay. ACS Chem Biol 2013; 8:1027-36. [PMID: 23480631 DOI: 10.1021/cb300584e] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A fundamental impediment to functional recovery from spinal cord injury (SCI) and traumatic brain injury is the lack of sufficient axonal regeneration in the adult central nervous system. There is thus a need to develop agents that can stimulate axon growth to re-establish severed connections. Given the critical role played by protein kinases in regulating axon growth and the potential for pharmacological intervention, small molecule protein kinase inhibitors present a promising therapeutic strategy. Here, we report a robust cell-based phenotypic assay, utilizing primary rat hippocampal neurons, for identifying small molecule kinase inhibitors that promote neurite growth. The assay is highly reliable and suitable for medium-throughput screening, as indicated by its Z'-factor of 0.73. A focused structurally diverse library of protein kinase inhibitors was screened, revealing several compound groups with the ability to strongly and consistently promote neurite growth. The best performing bioassay hit robustly and consistently promoted axon growth in a postnatal cortical slice culture assay. This study can serve as a jumping-off point for structure activity relationship (SAR) and other drug discovery approaches toward the development of drugs for treating SCI and related neurological pathologies.
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Affiliation(s)
- Hassan Al-Ali
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Stephan C. Schürer
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Vance P. Lemmon
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - John L. Bixby
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
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Abstract
OBJECTIVE This study aimed to investigate the effect of serum taken from patients with severe acute pancreatitis (SAP) on vascular endothelial permeability. METHODS The monolayer permeability of endothelial cells (ECs) was assessed. Morphological changes in ECs, induced by serum from patients with SAP were assessed. Expressions of RhoA, myosin light chain (MLC) phosphorylation, and VE-cadherin protein were detected by Western blot. RESULTS Compared with the control group, 20% SAP serum significantly increased endothelial monolayer permeability (P < 0.01), markedly induced transcellular F-actin redistribution with stress fiber formation and VE-cadherin derangement with fragmentations located at the cell borders, and increased gaps between ECs. Furthermore, Western blotting showed that SAP serum induced rapid activation of Rho protein, and markedly increased the level of phosphorylated MLC. However, pretreatment with Y-27632 (an inhibitor for Rho kinase) significantly inhibited endothelial hyperpermeability and the morphological changes of F-actin rearrangement and VE-cadherin redistribution. This was associated with a down-regulation of Rho protein expression and a reduction in the level of MLC phosphorylation. CONCLUSIONS The SAP serum induces the loss of vascular endothelial monolayer integrity, with endothelial F-actin stress fiber formation and VE-cadherin redistribution. One of the mechanisms for this process involves the activation of the Rho/Rho kinase signaling pathway.
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Seok YM, Kim HY, Garmaa O, Cha BY, Woo JT, Kim IK. Effects of magnolol on vascular contraction in rat aortic rings. Clin Exp Pharmacol Physiol 2011; 39:28-36. [DOI: 10.1111/j.1440-1681.2011.05629.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Szczepański M, Kamianowska M, Kamianowski G. Effects of fluorides on apoptosis and activation of human umbilical vein endothelial cells. Oral Dis 2011; 18:280-4. [PMID: 22093110 DOI: 10.1111/j.1601-0825.2011.01873.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine the effects of fluorides on endothelial functioning. MATERIALS AND METHODS We analyzed expressions of adhesion molecules, ICAM-1 and ICAM-3, and annexin V, on the surface of human umbilical vein endothelial cells (HUVECs) exposed to various concentrations of NaF and SnF(2) . We compared the effects of fluoride-induced changes with those obtained when stimulating HUVECs with TNF-α and verified whether N-acetyl cysteine (NAC), well-known antioxidant, can prevent both fluoride- and TNF-α-induced alterations. RESULTS The expressions of annexin V and ICAM-1 increased significantly after adding NaF (5.0 or 7.5mM) or Sn(2) F (0.5 or 0.75mM) to the culture medium. Pre-incubating HUVECs with NAC prevented the effects induced by 5.0 mM of NaF and 0.5 mM of Sn(2) F. Only the highest concentration of NaF (7.5mM) triggered the expression of ICAM-3. The expressions of all three molecules increased significantly upon stimulating the cultures with TNF-α (20ng ml(-1) ); these changes were not reversed by pre-incubation with NAC. CONCLUSIONS Fluorides induce oxidative stress, resulting in apoptosis and activation of HUVECs, manifested by an elevated expression of ICAM-1. The oxidative stress resulting from a stimulation by the highest NaF concentration triggers ICAM-3 expression on the HUVECs' surface.
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Affiliation(s)
- M Szczepański
- Department of Neonatology and Intensive Neonatal Care Unit, Medical University of Bialystok, Bialystok, Poland.
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Chen SC, Liu CC, Huang SY, Chiou SJ. Vascular hyperpermeability in response to inflammatory mustard oil is mediated by Rho kinase in mice systemically exposed to arsenic. Microvasc Res 2011; 82:182-9. [PMID: 21703283 DOI: 10.1016/j.mvr.2011.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2010] [Revised: 06/07/2011] [Accepted: 06/08/2011] [Indexed: 10/18/2022]
Abstract
The mechanisms underlying vascular dysfunction and cardiovascular disease induced by chronic arsenic exposure are not completely understood. We have previously shown that mice chronically fed sodium arsenite are hypersensitive to the permeability-increasing effects of inflammatory mustard oil. The aim of this study was to investigate whether RhoA/Rho kinase (ROCK)-mediated vascular leakage (hyperpermeability) is induced by mustard oil in mice systemically exposed to arsenic. Animals were orally fed water (control group) or sodium arsenite for 8weeks. We compared the blood pressure and microvessel density of the ears between these two groups. Both control and arsenic groups exhibited a similar mean arterial pressure and microvessel density. Microvessel permeability changes that occurred following mustard oil treatment in the presence of Y-27632, a ROCK inhibitor, were quantified using the Evans blue (EB) technique and vascular labeling with carbon particles. Both the excessive leakiness of EB and the high density of carbon-labeled microvessels upon stimulation with mustard oil in the arsenic-fed mice were reduced by Y-27632 treatment. However, RhoA and ROCK2 expression levels were similar between control and arsenic-fed mice. We further investigated ROCK2 levels and ROCK activity in the ears following mustard oil challenge. ROCK2 levels in mouse ears treated with mustard oil were higher in the arsenic group as compared with the control group. Following mustard oil application, ROCK activity was significantly higher in the arsenic-fed mice compared with the control mice. These findings indicate that increased ROCK2 levels and enhanced ROCK activity are responsible for mustard oil-induced vascular hyperpermeability in arsenic-fed mice.
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Affiliation(s)
- Shih-Chieh Chen
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
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A fluoride selective dipyrromethane-TCNQ colorimetric sensor based on charge-transfer. Talanta 2011; 84:947-51. [DOI: 10.1016/j.talanta.2011.02.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 02/19/2011] [Accepted: 02/21/2011] [Indexed: 11/19/2022]
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Seok YM, Jin F, Shin HM, Sung SH, Sohn UD, Cho JY, Kim IK. HMC05 attenuates vascular contraction through inhibition of RhoA/Rho-kinase signaling pathway. JOURNAL OF ETHNOPHARMACOLOGY 2011; 133:484-489. [PMID: 20965238 DOI: 10.1016/j.jep.2010.10.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 08/13/2010] [Accepted: 10/08/2010] [Indexed: 05/30/2023]
Abstract
AIM OF THE STUDY HMC05, an extract from eight different herbal mixtures, has been developed to treat cardiovascular disease. This extract has a vasorelaxant and anti-atherosclerotic action. We hypothesized that HMC05 attenuates vascular contraction through inhibition of the RhoA/Rho-kinase signaling pathway. MATERIALS AND METHODS Rat aortic ring preparations were mounted in organ baths and subjected to contraction and relaxation. Phosphorylation of 20 kDa myosin light chains (MLC(20)) and myosin phosphatase targeting subunit 1 (MYPT1) were examined by immunoblot. We also measured the amount of GTP RhoA as a marker for RhoA activation. RESULTS In endothelium-denuded aortic ring preparations, HMC05 relaxed vascular contraction induced by 6.0 mM NaF, 100 nM phenylephrine, 30 nM thromboxane A(2) agonist U46619 or 1.0 μM protein kinase C (PKC) activator phorbol-12,13-dibutyrate (PDBu) in a decreasing order. HMC05 relaxed aortic ring preparations precontracted with sodium fluoride (NaF) whether endothelium was intact or denuded. Pre-incubation with HMC05 for 30 min dose-dependently inhibited the NaF-induced contractile response. In vascular strips, HMC05 decreased the phosphorylation level of both MLC(20) and MYPT1(Thr855) induced by 6.0 mM NaF. Furthermore, HMC05 decreased the amount of GTP RhoA activated by NaF. CONCLUSIONS HMC05 attenuates vascular contraction through inhibition of the RhoA/Rho-kinase signaling pathway. HMC05 may be useful for the treatment and/or prevention of cardiovascular diseases associated with activation of RhoA/Rho-kinase signaling pathway.
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Affiliation(s)
- Young Mi Seok
- Department of Pharmacology, Kyungpook National University School of Medicine, Daegu 700-422, Republic of Korea
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Barbier O, Arreola-Mendoza L, Del Razo LM. Molecular mechanisms of fluoride toxicity. Chem Biol Interact 2010; 188:319-33. [DOI: 10.1016/j.cbi.2010.07.011] [Citation(s) in RCA: 638] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 07/07/2010] [Accepted: 07/12/2010] [Indexed: 01/27/2023]
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Seok YM, Choi YW, Kim GD, Kim HY, Takuwa Y, Kim IK. Effects of gomisin A on vascular contraction in rat aortic rings. Naunyn Schmiedebergs Arch Pharmacol 2010; 383:45-56. [DOI: 10.1007/s00210-010-0571-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 09/08/2010] [Indexed: 01/06/2023]
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Ramani S, Patil N, Jayabaskaran C. UV-B induced transcript accumulation of DAHP synthase in suspension-cultured Catharanthus roseus cells. J Mol Signal 2010; 5:13. [PMID: 20704760 PMCID: PMC2930624 DOI: 10.1186/1750-2187-5-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 08/13/2010] [Indexed: 11/10/2022] Open
Abstract
The enzyme 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase (EC 4.1.2.15) catalyzes the first committed step in the shikimate pathway of tryptophan synthesis, an important precursor for the production of terpenoid indole alkaloids (TIAs). A full-length cDNA encoding nuclear coded chloroplast-specific DAHP synthase transcript was isolated from a Catharanthus roseus cDNA library. This had high sequence similarity with other members of plant DAHP synthase family. This transcript accumulated in suspension cultured C. roseus cells on ultraviolet (UV-B) irradiation. Pretreatment of C.roseus cells with variety of agents such as suramin, N-acetyl cysteine, and inhibitors of calcium fluxes and protein kinases and MAP kinase prevented this effect of UV-B irriadiation. These data further show that the essential components of the signaling pathway involved in accumulation DAHP synthase transcript in C. roseus cells include suramin-sensitive cell surface receptor, staurosporine-sensitive protein kinase and MAP kinase.
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Affiliation(s)
- Shilpa Ramani
- Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
| | - Nandadevi Patil
- Department of Biochemistry, Indian Institute of Science, Bangalore-560012, India
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Abstract
BACKGROUND INFORMATION Fluoride is a well-known G-protein activator. Exposure of cultured cells to its derivatives results in actin cytoskeleton remodelling. Podosomes are actin-based structures endowed with adhesion and matrix-degradation functions. This study investigates actin cytoskeleton reorganization induced by fluoride in endothelial cells. RESULTS Treatment of cultured endothelial cells with sodium fluoride (NaF) results in a rapid and potent stimulation of podosome formation. Furthermore, we show that Cdc42 (cell-division cycle 42), Rac1 and RhoA activities are stimulated in NaF-treated cells. However, podosome assembly is dependent on Cdc42 and Rac1, but not RhoA. Although the sole activation of Cdc42 is sufficient to induce individual podosomes, a balance between RhoGTPase activities regulates podosome formation in response to NaF, which in this case are often found in groups or rosettes. As in other models, podosome formation in endothelial cells exposed to NaF also involves Src. Finally, we demonstrate that NaF-induced podosomes are fully competent for matrix protein degradation. CONCLUSIONS Taken together, our findings establish NaF as a novel inducer of podosomes in endothelial cells in vitro.
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Liu T, Guevara OE, Warburton RR, Hill NS, Gaestel M, Kayyali US. Modulation of HSP27 alters hypoxia-induced endothelial permeability and related signaling pathways. J Cell Physiol 2009; 220:600-10. [PMID: 19373869 DOI: 10.1002/jcp.21773] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This manuscript describes how the permeability of pulmonary artery microvascular endothelial cell (RPMEC) monolayer is elevated by hypoxia and the role played by HSP27 phosphorylation. p38 MAP kinase activation leading to HSP27 phosphorylation was previously shown by our laboratory to alter the actin cytoskeleton and tethering properties of RPMEC. This effect was independent of hypoxia-induced contractility which was ROCK-dependent rather than HSP27-dependent. Results described here show that increased HSP27 phosphorylation not only does not underlie hypoxia-induced permeability, but may actually augment the endothelial barrier. Hypoxia causes gap formation between RPMEC and increases MLC2 phosphorylation. The phosphorylation of MYPT1, which inhibits MLC2 phosphatase, is also increased in hypoxia. In addition, FAK phosphorylation, which alters focal adhesion signaling, is increased in hypoxia. Overexpressing phosphomimicking HSP27 (pmHSP27), which induces significant actin stress fiber formation, surprisingly renders RPMEC resistant to hypoxia- or TGFbeta-induced permeability. siRNA against pmHSP27 reverses the increased actin stress fiber formation in pmHSP27-overexpressing cells, and disrupting actin stress fibers in pmHSP27-overexpressing RPMEC renders them more susceptible to hypoxia. Finally, hypoxia-induced gap formation, as well as phosphorylation of MLC2, MYPT1 and FAK are almost abolished by overexpressing pmHSP27 in RPMEC. These effects of pmHSP27 overexpression might represent decreased cytoskeletal plasticity and increased tethering which counteracts permeability-inducing contractility. Thus hypoxia activates two pathways one leading to contractility and increased permeability, the other leading to actin stress fibers, stronger adhesion, and reduced permeability. Altering HSP27 phosphorylation, which tips the balance towards decreased permeability, might be targeted in managing endothelial barrier dysfunction.
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Affiliation(s)
- Tiegang Liu
- Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Houle F, Poirier A, Dumaresq J, Huot J. DAP kinase mediates the phosphorylation of tropomyosin-1 downstream of the ERK pathway, which regulates the formation of stress fibers in response to oxidative stress. J Cell Sci 2007; 120:3666-77. [PMID: 17895359 DOI: 10.1242/jcs.003251] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Endothelial cells are actively involved in regulating the exchanges between blood and tissues. This function is tightly dependent on actin cytoskeleton dynamics and is challenged by a wide variety of stimuli, including oxidative stress. In endothelial cells, oxidative stress quickly activates the extracellular-signal-regulated kinase (ERK) MAP kinase, which results in the phosphorylation of tropomyosin. Here, we investigated further the mechanisms of tropomyosin phosphorylation and its function in actin remodeling. We identified, for the first time, death-associated protein kinase 1 (DAP kinase 1) as the kinase that phosphorylates tropomyosin-1 in response to ERK activation by hydrogen peroxide (H(2)O(2)). We also report that the phosphorylation of tropomyosin-1 mediated by DAP kinase occurs on Ser283. Moreover, the expression of the pseudophosphorylated tropomyosin mutant Ser283Glu triggers by itself the formation of stress fibers in untreated cells, and the effect is maintained in H(2)O(2)-treated cells in which DAP kinase expression is knocked-down by siRNA. By contrast, the expression of the nonphosphorylatable tropomyosin mutant Ser283Ala is not associated with stress fibers and leads to membrane blebbing in response to H(2)O(2). Our finding that tropomyosin-1 is phosphorylated downstream of ERK and DAP kinase and that it helps regulate the formation of stress fibers will aid understanding the role of this protein in regulating the endothelial functions associated with cytoskeletal remodeling.
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Affiliation(s)
- François Houle
- Le Centre de recherche en cancérologie de l'Université Laval, 9 rue McMahon, Québec G1R 2J6, Canada
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Csortos C, Kolosova I, Verin AD. Regulation of vascular endothelial cell barrier function and cytoskeleton structure by protein phosphatases of the PPP family. Am J Physiol Lung Cell Mol Physiol 2007; 293:L843-54. [PMID: 17693486 DOI: 10.1152/ajplung.00120.2007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Reversible phosphorylation of cytoskeletal and cytoskeleton-associated proteins is a significant element of endothelial barrier function regulation. Therefore, understanding the mechanisms of phosphorylation/dephosphorylation of endothelial cell cytoskeletal proteins is vital to the treatment of severe lung disorders such as high permeability pulmonary edema. In vivo, there is a controlled balance between the activities of protein kinases and phosphatases. Due to various external or internal signals, this balance may be shifted. The actual balances at a given time alter the phosphorylation level of certain proteins with appropriate physiological consequences. The latest information about the structure and regulation of different types of Ser/Thr protein phosphatases participating in the regulation of endothelial cytoskeletal organization and barrier function will be reviewed here.
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Affiliation(s)
- Csilla Csortos
- Department of Medicine, Division of Biological Sciences, The University of Chicago, Chicago, Illinois, USA
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Tanaka N, Nejime N, Kagota S, Kubota Y, Yudo K, Nakamura K, Kunitomo M, Takahashi K, Hashimoto M, Shinozuka K. ATP participates in the regulation of microvessel permeability. J Pharm Pharmacol 2006; 58:481-7. [PMID: 16597365 DOI: 10.1211/jpp.58.4.0007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
We demonstrated previously that stimulation of the P2Y receptor enhanced the macromolecular permeability of cultured endothelial cell monolayers via the paracellular pathway. To determine whether the P2Y receptor participates in the regulation of permeability in intact microvessels, we have examined the effects of exogenous and endogenous ATP on the permeation of the surface tissue of perfused rat tail caudal artery using a fluorescein isothiocyanate-dextran (FD-4; MW 4400; 1.0 mg mL(-1)). The permeation of FD-4 was assessed by a confocal fluorescence imaging system. We found that 2-methylthioadenosine 5'-triphosphate, a P2Y receptor agonist, enhanced the fluorescence intensity of FD-4 in the surface of the rat caudal artery tissue and that it was inhibited by pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid, a P2 receptor antagonist. Also, noradrenaline, a sympathetic neurotransmitter, and bradykinin, an inflammatory autacoid, enhanced the fluorescence intensity of FD-4 in the surface tissue of the rat caudal artery. The enhancement by noradrenaline was significantly inhibited by the P2 receptor antagonist. In addition, noradrenaline and bradykinin caused the release of ATP, ADP, AMP and adenosine from the endothelium of the rat caudal artery. These results indicated that the exogenous and endogenous ATP increased the macromolecular permeability of blood capillaries via the P2Y receptor. Such purinergic regulation of endothelial permeability may function in physiological and pathophysiological conditions.
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Affiliation(s)
- Naoko Tanaka
- First Department of Pharmacology, School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, Nobeoka, Miyazaki 882-8508, Japan
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Feng Z, Wei C, Chen X, Wang J, Cheng H, Zhang X, Hong Q, Shi S, Fu B, Wei R. Essential role of Ca2+ release channels in angiotensin II-induced Ca2+ oscillations and mesangial cell contraction. Kidney Int 2006; 70:130-8. [PMID: 16723987 DOI: 10.1038/sj.ki.5000342] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The increased resistance of the glomerulus as a result of contractile dysfunction of mesangial cells (MCs) is associated with reduction of glomerular filtration rate and development of glomerulosclerosis. Evidences show MCs contraction changes with intracellular Ca(2+) concentration ([Ca(2+)](i)). Here, we explore the mechanism of angiotensin II (AngII)-induced Ca(2+) oscillations and MCs contraction. Primary MCs from 3-month-old and 28-month-old rats were used for detection of Ca(2+) oscillations and MC planar area with confocal microscopy. AngII could induce typical Ca(2+) oscillations and contraction of MCs. This process was abolished by thapsigargin, 2-aminoethoxydiphenyl borate, or 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphorylcholine, and partially inhibited by ryanodine, but could not be inhibited in the absence of extracellular Ca(2+). Ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate (InsP(3)) receptors displayed a strong colocalization, which may contribute to the amplification of Ca(2+) response. MLC(20) phosphorylation and MC planar area were associated with AngII-induced Ca(2+) oscillations. The frequency of Ca(2+) oscillations was dependent on the AngII concentration and correlated with the MCs' contractive extent, which could be attenuated by KN-93. The amplitude reduction of oscillations correlated with the decrease in aging-related contraction. In conclusion, [Ca(2+)](i) response of MCs to AngII is characterized by repetitive spikes through the following repetitive cycles: Ca(2+) release by phospholipase C -InsP(3) pathway, Ca(2+) amplification by Ca(2+)-activated RyRs and Ca(2+) reuptake by the endoplasmic reticulum. MCs contraction can be modulated by oscillations not only in an AngII-induced frequency-dependent mode but also in an aging-related, amplitude-dependent mode.
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Affiliation(s)
- Z Feng
- Department of Nephrology, Kidney Center and Key Lab of PLA, Chinese General Hospital of PLA, Beijing, China
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Bogatcheva NV, Wang P, Birukova AA, Verin AD, Garcia JGN. Mechanism of fluoride-induced MAP kinase activation in pulmonary artery endothelial cells. Am J Physiol Lung Cell Mol Physiol 2006; 290:L1139-45. [PMID: 16414982 DOI: 10.1152/ajplung.00161.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In this study, we demonstrate that challenge of endothelial cells (EC) with NaF, a recognized G protein activator and protein phosphatase inhibitor, leads to a significant Erk activation, with increased phosphorylation of the well-known Erk substrate caldesmon. Inhibition of the Erk MAPK, MEK, by U0126 produces a marked decrease in NaF-induced caldesmon phosphorylation. NaF transiently increases the activity of the MEK kinase known as Raf-1 (approximately 3- to 4-fold increase over basal level), followed by a sustained Raf-1 inhibition (approximately 3- to 4-fold decrease). Selective Raf-1 inhibitors (ZM-336372 and Raf-1 inhibitor 1) significantly attenuate NaF-induced Erk and caldesmon phosphorylation. Because we have previously shown that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) participates in Erk activation in thrombin-challenged cells, we next explored if CaMKII is involved in NaF-induced EC responses. We found that in NaF-treated EC, CaMKII activity increases in a time-dependent manner with maximal activity at 10 min (approximately 4-fold increase over a basal level). Pretreatment with KN93, a specific CaMKII inhibitor, attenuates NaF-induced barrier dysfunction and Erk phosphorylation. The Rho inhibitor C3 exotoxin completely abolishes NaF-induced CaMKII activation. Collectively, these data suggest that sequential activation of Raf-1, MEK, and Erk is modulated by Rho-dependent CaMKII activation and represents important NaF-induced signaling response. Caldesmon phosphorylation occurring by an Erk-dependent mechanism in NaF-treated pulmonary EC may represent a link between NaF stimulation and contractile responses of endothelium.
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Affiliation(s)
- Natalia V Bogatcheva
- Section of Pulmonary and Critical Care, Department of Medicine, University of Chicago, 5841 S. Maryland Avenue, W604, Chicago, IL 60637, USA
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Satpathy M, Gallagher P, Jin Y, Srinivas SP. Extracellular ATP opposes thrombin-induced myosin light chain phosphorylation and loss of barrier integrity in corneal endothelial cells. Exp Eye Res 2005; 81:183-92. [PMID: 16080912 DOI: 10.1016/j.exer.2005.01.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 01/07/2005] [Accepted: 01/24/2005] [Indexed: 10/25/2022]
Abstract
Increased contractility of the actin cytoskeleton by phosphorylation of the regulatory myosin light chain (MLC) results in a loss of barrier integrity in corneal endothelial cells. This study has investigated the effect of extracellular ATP, which may influence both Ca2+ and cAMP signalling, on MLC phosphorylation and barrier integrity in cultured bovine corneal endothelial cells (BCEC) known to express A2B and P2Y purinergic receptors, and ecto-nucleotidases. Extracellular ATP (100 microM) promoted MLC dephosphorylation (pMLC=61.8% at 18 min; n=9). Pre-exposure to ARL-67156, an ecto-nucleotidase inhibitor, prevented ATP-induced dephosphorylation. Other P2Y agonists, UTP and ATPgammaS, also induced MLC dephosphorylation but to a lesser degree compared to ATP. Thrombin (2 U/ml), which activate Rho kinase through PAR-1 receptors in the endothelium, induced MLC phosphorylation (pMLC=129.2%; n=14). This phosphorylation was completely abolished by concomitant exposure to ATP. When cells were pretreated with adenosine (100 microM; A2B agonist) or forskolin (10 microM), thrombin-induced phosphorylation was suppressed. ATP also led to a significant increase in cAMP (> 3-fold compared to 10 microM adenosine). Thrombin-induced increase in trans-endothelial flux of horseradish peroxidase (44 kDa) and disruption of the cortical actin were suppressed by ATP. These findings indicate that in BCEC (1) ATP induces elevated cAMP through its metabolite adenosine leading to MLC dephosphorylation, (2) Stimulation of P2Y2 receptors also leads to activation of MLCP since UTP- and ATPgammaS caused MLC dephosphorylation, and (3) ATP is antagonistic to thrombin since the latter inhibits MLCP through increased activity of Rho kinase. These findings further emphasize the role of contractility of the actin cytoskeleton in regulating the barrier integrity of corneal endothelium.
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Affiliation(s)
- M Satpathy
- School of Optometry, Indiana University, 800 East Atwater Avenue, Indiana University, Bloomington, IN 47405, USA
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Srinivas SP, Satpathy M, Gallagher P, Larivière E, Van Driessche W. Adenosine induces dephosphorylation of myosin II regulatory light chain in cultured bovine corneal endothelial cells. Exp Eye Res 2004; 79:543-51. [PMID: 15381038 DOI: 10.1016/j.exer.2004.06.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2004] [Accepted: 06/25/2004] [Indexed: 10/26/2022]
Abstract
PURPOSE Dephosphorylation of the myosin II regulatory light chain (MLC) promotes barrier integrity of cellular monolayers through relaxation of the actin cytoskeleton. This study has investigated the influence of adenosine (ADO) on MLC phosphorylation in cultured bovine corneal endothelial cells (BCEC). METHODS MLC phosphorylation was assessed by urea-glycerol gel electrophoresis and immunoblotting. Elevation of cAMP in response to agonists of A2b receptors (subtype of P1 purinergic receptors) was confirmed by phosphorylation of the cAMP response element binding protein (CREB), which was determined by Western blotting. Activation of MAP kinases (i.e. activated ERK1 and ERK2) was assessed by Western blotting to examine their influence on MLC phosphorylation. Transepithelial electrical resistance (TER) of cells grown on porous filters was measured to assess the altered barrier integrity. RESULTS Exposure to ADO (200 microm; 30 min) and N-ethyl (carboxamido) adenosine (NECA; 50 microm; 30 min), known agonists of A2b receptors, induced phosphorylation of CREB similar to forskolin (FSK, 20 microm; 30 min), a direct activator of adenylate cyclase. Exposure to ADO, NECA, and FSK led to dephosphorylation of MLC by 51, 40, and 47%, respectively. ADO-induced dephosphorylation was dose-dependent with as much as 31% dephosphorylation at 1 microm ADO. CGS-21680, a selective A2a agonist, neither induced MLC dephosphorylation nor CREB phosphorylation. ADO phosphorylated MAP kinases which could be prevented by exposure to the MAP kinase-specific inhibitor, U0126 (10 microM). NECA and FSK also induced ERK1 and ERK2 activation similar to ADO. Exposure to U0126 inhibited MLC phosphorylation under basal conditions by 17%. ADO-induced MLC dephosphorylation was enhanced by a simultaneous exposure to U0126 (25% increase in dephosphorylation). Exposure to ADO caused an increase in TER from 17 to 22 ohms cm2. CONCLUSIONS (1) CREB phosphorylation in response to ADO and NECA, which indicates activation of the cAMP-PKA axis, suggests expression of A2b receptors in BCEC. (2) ERK1 and ERK2, activated by cAMP and A2b receptors, promote MLC phosphorylation. However, the net result of cAMP elevation is MLC dephosphorylation, presumably because the competing pathways involving inactivation of MLCK and/or ROCK are dominant (Rho-associated coiled coil-containing protein kinase or Rho kinase). (3) Consistent with MLC dephosphorylation, exposure to ADO increases TER, which suggests increased barrier integrity.
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Affiliation(s)
- S P Srinivas
- School of Optometry, Indiana University, 800 Atwater Ave, Bloomington, IN 47405, USA.
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Satpathy M, Gallagher P, Lizotte-Waniewski M, Srinivas SP. Thrombin-induced phosphorylation of the regulatory light chain of myosin II in cultured bovine corneal endothelial cells. Exp Eye Res 2004; 79:477-86. [PMID: 15381032 DOI: 10.1016/j.exer.2004.06.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2004] [Accepted: 06/14/2004] [Indexed: 10/26/2022]
Abstract
PURPOSE Phosphorylation of the regulatory light chain of myosin II (referred to as myosin light chain or MLC) leads to a loss of barrier integrity in cellular monolayers by an increase in the contractility of the cortical actin cytoskeleton. This effect has been examined in corneal endothelial (CE) cells. METHODS Experiments were performed using cultured bovine CE cells (BCEC). MLC phosphorylation was induced by a thrombin-mediated activation of the proteinase-activated receptor-1 (PAR-1). Expression of MLC kinase (MLCK), a Ca2+/calmodulin-dependent protein kinase that phosphorylates MLC at its Ser-19 and Thr-18 residues, was determined by RT-PCR and Western blotting. Expression of PAR-1, RhoA, and Rho kinase-1 (effector of RhoA) was ascertained by RT-PCR. MLC phosphorylation was assessed by urea-glycerol gel electrophoresis followed by immunoblotting. The effects of Rho kinase-1 and PKC were characterized by using their selective inhibitors, Y-27632 and chelerythrine, respectively. Reorganization of the cytoskeleton was evaluated by the phalloidin staining of actin. [Ca2+]i was measured using Fura-2. The barrier integrity was assayed as permeability of BCEC monolayers to horseradish peroxidase (HRP; 44 kDa). RESULTS RT-PCR showed expression of MLCK, PAR-1, Rho kinase-1, and RhoA. Western blotting indicated expression of the non-muscle and smooth muscle isoforms of MLCK. Exposure to thrombin induced an increase in [Ca2+]i with the peak unaffected by an absence of extracellular Ca2+. Pre-exposure to thrombin (2 U ml(-1); 2 min) led to mono- and di-phosphorylation of MLC. Under both basal conditions and in the presence of thrombin, MLC phosphorylation was prevented by chelerythrine (10 microm) and Y-27632 (<25 microm). Thrombin led to inter-endothelial gaps secondary to the disruption of the cortical actin cytoskeleton, which under resting conditions was organized as a perijunctional actomyosin ring (PAMR). These responses were blocked by pre-treatment with Y-27632. Thrombin also increased permeability to HRP, which was abolished by pre-treatment with Y-27632. CONCLUSIONS Thrombin induces MLC phosphorylation in BCEC. The consequent increase in the contractility of the actin cytoskeleton produces a centripetal force resulting in inter-endothelial gaps and a breakdown of barrier integrity. These responses are PKC- and Rho kinase-dependent. [Ca2+]i increase, as well as sensitivity of the thrombin response to PKC and Rho kinase inhibitors, are consistent with the expression of PAR-1 receptors in BCEC. Thrombin-induced hyperpermeability is a model to investigate barrier dysfunction induced by MLC phosphorylation.
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Affiliation(s)
- M Satpathy
- School of Optometry, Indiana University, 800 East Atwater Avenue, Bloomington, IN 47405, USA
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Harrington EO, Newton J, Morin N, Rounds S. Barrier dysfunction and RhoA activation are blunted by homocysteine and adenosine in pulmonary endothelium. Am J Physiol Lung Cell Mol Physiol 2004; 287:L1091-7. [PMID: 15286003 DOI: 10.1152/ajplung.00421.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
RhoA GTPases modulate endothelial permeability. We have previously shown that adenosine and homocysteine enhance basal barrier function in pulmonary artery endothelial cells by a mechanism involving diminution of RhoA carboxyl methylation and activity. In the current study, we investigated the effects of adenosine and homocysteine on endothelial monolayer permeability in cultured monolayers. Adenosine and homocysteine significantly attenuated thrombin-induced endothelial barrier dysfunction and intercellular gap formation. We found significantly diminished RhoA associated with the membrane subcellular fraction in endothelial cells pretreated with adenosine and homocysteine, compared with vehicle-treated endothelial cells. Additionally, adenosine and homocysteine significantly blunted RhoA activation following thrombin exposure. Incubation with adenosine and homocysteine also enhanced in vitro interactions between RhoA and RhoGDI, as well as subcellular translocation of p190RhoGAP to the cytosol. These data demonstrate that elevated intracellular concentrations of homocysteine and adenosine enhance endothelial barrier function in cultured endothelial cells isolated from the main pulmonary artery and lung microvasculature, suggesting a potentially protective effect against pulmonary edema in response to lung injury. We speculate that homocysteine and adenosine modulate the level of endothelial barrier dysfunction through modulation of RhoA posttranslational processing resulting in diminished GTPase activity through altered interactions with modulators of RhoA activation.
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Affiliation(s)
- Elizabeth O Harrington
- Pulmonary Vascular Research Laboratory, Providence Veterans Affairs Medical Center, Providence, RI 02908, USA
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Lundblad C, Bentzer P, Grände PO. Inhibition of Rho kinase decreases hydraulic and protein microvascular permeability in cat skeletal muscle. Microvasc Res 2003; 66:126-33. [PMID: 12935770 DOI: 10.1016/s0026-2862(03)00041-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rho-associated kinases are involved in regulation of actin-myosin contractility and the organization of the actin cytoskeleton in both endothelial and smooth muscle cells. By influencing the contraction of the intraendothelial filaments, Rho kinases may affect the size of the interendothelial gaps and thereby influence microvascular permeability. The aim of the study was therefore to investigate whether Rho kinases influence hydraulic and protein microvascular permeability. The study was performed on the autoperfused cat skeletal muscle. A capillary filtration coefficient (CFC) technique was used to evaluate changes in hydraulic permeability, and protein permeability was evaluated by estimation of the change in the reflection coefficient for albumin. In the first part of each experiment, the effects on CFC of three doses of the Rho kinase inhibitor Y-27632 of about 0.35, 0.70, and 1.05 microg/h per ml plasma flow were determined. There was a reduction in CFC at the lowest dose, and a tendency to further reduction at the higher doses used, reaching a decrease in CFC of 20%. The effects on CFC of the high and the middle dose did not differ. The reflection coefficient for albumin was increased by 31% following infusion of the highest dose of Y-27632. We conclude that hydraulic and protein microvascular permeability increase by Rho kinase activation, and that Rho kinase is involved in regulation of microvascular permeability.
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Affiliation(s)
- C Lundblad
- Department of Physiological Sciences, University of Lund, Sweden.
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Adamson RH, Zeng M, Adamson GN, Lenz JF, Curry FE. PAF- and bradykinin-induced hyperpermeability of rat venules is independent of actin-myosin contraction. Am J Physiol Heart Circ Physiol 2003; 285:H406-17. [PMID: 12649070 DOI: 10.1152/ajpheart.00021.2003] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that acutely induced hyperpermeability is dependent on actin-myosin contractility by using individually perfused mesentery venules of pentobarbital-anesthetized rats. Venule hydraulic conductivity (Lp) was measured to monitor hyperpermeability response to the platelet-activating factor (PAF) 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine or bradykinin. Perfusion with PAF (10 nM) induced a robust transient high Lp [24.3 +/- 1.7 x 10-7 cm/(s.cmH2O)] that peaked in 8.9 +/- 0.5 min and then returned toward control Lp [1.6 +/- 0.1 x 10-7 cm/(s.cmH2O)]. Reconstruction of venular segments with the use of transmission electron microscopy of serial sections confirmed that PAF induces paracellular inflammatory gaps. Specific inhibition of myosin light chain kinase (MLCK) with 1-10 microM 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7) failed to block the PAF Lp response or change the time-to-peak Lp. ML-7 reduced baseline Lp 50% at 40 min of pretreatment. ML-7 also increased the rate of recovery from PAF hyperpermeability measured as the decrease of half-time of recovery from 4.8 +/- 0.7 to 3.2 +/- 0.3 min. Inhibition of myosin ATPase with 5-20 mM 2,3-butanedione 2-monoxime also failed to alter the hyperpermeability response to PAF. Similar results were found using ML-7 to modulate responses. These experiments indicate that an actin-myosin contractile mechanism modulated by MLCK does not contribute significantly to the robust initial increase in permeability of rat venular microvessels exposed to two common inflammatory mediators. The results are consistent with paracellular gap formation by local release of endothelial-endothelial cell adhesion structures in the absence of contraction by the actin-myosin network.
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Affiliation(s)
- R H Adamson
- Departmentof Human Physiology, School of Medicine, University of California-Davis, Davis, CA 95616, USA.
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Barros LF, Kanaseki T, Sabirov R, Morishima S, Castro J, Bittner CX, Maeno E, Ando-Akatsuka Y, Okada Y. Apoptotic and necrotic blebs in epithelial cells display similar neck diameters but different kinase dependency. Cell Death Differ 2003; 10:687-97. [PMID: 12761577 DOI: 10.1038/sj.cdd.4401236] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Apoptotic and necrotic blebs elicited by H(2)O(2) were compared in terms of dynamics, structure and underlying biochemistry in HeLa cells and Clone 9 cells. Apoptotic blebs appeared in a few minutes and required micromolar peroxide concentrations. Necrotic blebs appeared much later, prior to cell permeabilization, and required millimolar peroxide concentrations. Strikingly, necrotic blebs grew at a constant rate, which was unaffected throughout successive cycles of budding and detachment. At 1 microm diameter, the necks of necrotic and apoptotic blebs were almost identical. ATP depletion was discarded as a major factor for both types of bleb. Inhibition of ROCK-I, MLCK and p38MAPK strongly decreased apoptotic blebbing but had no effect on necrotic blebbing. Taken together, these data suggest the existence of a novel structure of fixed dimensions at the neck of both types of plasma membrane blebs in epithelial cells. However, necrotic blebs can be distinguished from apoptotic blebs in their susceptibility to actomyosin kinase inhibition.
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Affiliation(s)
- L F Barros
- Department of Cell Physiology, National Institute for Physiological Sciences, School of Life Science, Okazaki, Aichi 444-8585, Japan.
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Houle F, Rousseau S, Morrice N, Luc M, Mongrain S, Turner CE, Tanaka S, Moreau P, Huot J. Extracellular signal-regulated kinase mediates phosphorylation of tropomyosin-1 to promote cytoskeleton remodeling in response to oxidative stress: impact on membrane blebbing. Mol Biol Cell 2003; 14:1418-32. [PMID: 12686598 PMCID: PMC153111 DOI: 10.1091/mbc.e02-04-0235] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Oxidative stress induces in endothelial cells a quick and transient coactivation of both stress-activated protein kinase-2/p38 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases. We found that inhibiting the ERK pathway resulted, within 5 min of oxidative stress, in a misassembly of focal adhesions characterized by mislocalization of key proteins such as paxillin. The focal adhesion misassembly that followed ERK inhibition with the mitogen-activated protein kinase kinase (MEK) inhibitor PD098059 (2'-amino-3'-methoxyflavone) or with a kinase negative mutant of ERK in the presence of H(2)O(2) resulted in a quick and intense membrane blebbing that was associated with important damage to the endothelium. We isolated by two-dimensional gel electrophoresis a PD098059-sensitive phosphoprotein of 38 kDa that we identified, by mass spectrometry, as tropomyosin-1. In fact, H(2)O(2) induced a time-dependent phosphorylation of tropomyosin that was sensitive to inhibition by PD098059 and UO126 (1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butanediane). Tropomyosin phosphorylation was also induced by expression of a constitutively activated form of MEK1 (MEK(CA)), which confirms that its phosphorylation resulted from the activation of ERK. In unstimulated cells, tropomyosin-1 was found diffuse in the cells, whereas it quickly colocalized with actin and stress fibers upon stimulation of ERK by H(2)O(2) or by expression of MEK(CA). We propose that phosphorylation of tropomyosin-1 downstream of ERK by contributing to formation of actin filaments increases cellular contractility and promotes the formation of focal adhesions. Incidentally, ML-7 (1-[5iodonaphthalene-1-sulfonyl]homopiperazine, HCl), an inhibitor of cell contractility, inhibited phosphorylation of tropomyosin and blocked the formation of stress fibers and focal adhesions, which also led to membrane blebbing in the presence of oxidative stress. Our finding that tropomyosin-1 is phosphorylated downstream of ERK, an event that modulates its interaction with actin, may lead to further understanding of the role of this protein in regulating cellular functions associated with cytoskeletal remodeling.
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Affiliation(s)
- François Houle
- Le Centre de Recherche en Cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, Québec G1R 2J6, Canada
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Edens HA, Parkos CA. Neutrophil transendothelial migration and alteration in vascular permeability: focus on neutrophil-derived azurocidin. Curr Opin Hematol 2003; 10:25-30. [PMID: 12483108 DOI: 10.1097/00062752-200301000-00005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Infiltration and accumulation of polymorphonuclear leukocytes within the tissues is a hallmark of the acute inflammatory response. A prominent feature of acute inflammation is enhanced vascular permeability resulting in edema formation. Such changes in vascular permeability have been known to be dependent upon polymorphonuclear leukocyte interactions with the vascular endothelium. Careful investigation has shown clearly that permeability changes can occur without polymorphonuclear leukocyte transendothelial migration, and that polymorphonuclear leukocyte migration can occur without permeability alteration. The underlying mechanisms of polymorphonuclear leukocyte-stimulated changes in endothelial barrier function have remained elusive. Endothelial activation and polymorphonuclear leukocyte adhesion to the endothelium are both required for polymorphonuclear leukocyte-induced changes in vascular permeability. Polymorphonuclear leukocyte-derived azurocidin plays a major role in this polymorphonuclear leukocyte-evoked alteration in endothelial permeability. Azurocidin is released after activation of polymorphonuclear leukocytes, such as after ligation of the major adhesive integrin CD11b/CD18. Understanding how polymorphonuclear leukocytes alter vascular permeability may provide targets for new drugs for appropriate therapeutic intervention in acute and chronic inflammatory diseases. This review focuses on the role of polymorphonuclear leukocyte-derived azurocidin in alteration of vascular permeability.
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Affiliation(s)
- Heather A Edens
- Division of Gastrointestinal Pathology, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia 30322, USA
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Partanen S. Inhibition of human renal acid phosphatases by nephrotoxic micromolar concentrations of fluoride. EXPERIMENTAL AND TOXICOLOGIC PATHOLOGY : OFFICIAL JOURNAL OF THE GESELLSCHAFT FUR TOXIKOLOGISCHE PATHOLOGIE 2002; 54:231-7. [PMID: 12484561 DOI: 10.1078/0940-2993-00251] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fluoride is considered to be a nephrotoxic substance, due to the association of 50-180 microM serum concentrations of fluoride with dose-related, subclinical to overt clinical renal impairment. At these concentrations the cellular targets of fluoride in renal tissue remain unknown. Fluoride at micromolar concentrations inhibits some enzymes including phosphatases. Here the effects of fluoride on a recently characterized acid phosphatase complex present only in a few human tissues were studied. This enzyme complex consists of alkaline fixation-resistant beta-glycerophosphatase and tartrate-resistant a-naphthyl phosphatase, and these are different from activities of known types of acid phosphatase and specific phosphatases. In kidney, strong activities for this complex are detected only in the endothelium of the afferent arterioles and in glomeruli. It appeared that alkaline fixation-resistant and lysosomal acid phosphatase activities were significantly inhibited in afferent arterioles and glomeruli by 75 microM fluoride. Tartrate-resistant activity was significantly inhibited by greater concentrations (250 microM). Inhibition of acid phosphatases in the afferent arterioles and glomeruli may be one renal target of fluoride nephrotoxicity. Although the physiological substrates of this acid phosphatase complex are unknown, its specific and restricted location may indicate a role in regulation of renal circulation.
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Affiliation(s)
- Seppo Partanen
- Department of Pathology, Helsinki University Central Hospital, Jorvi Hospital, Espoo, Finland.
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Abstract
Endothelial permeability depends on the integrity of intercellular junctions as well as actomyosin-based cell contractility. Rho GTPases have been implicated in signalling by many vasoactive substances including thrombin, tumour necrosis factor alpha (TNF-alpha), bradykinin, histamine, lysophosphatidic acid (LPA), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF). Two Rho family GTPases, Rho and Rac, have emerged as key regulators acting antagonistically to regulate endothelial barrier function: Rho increases actomyosin contractility, which facilitates breakdown of intercellular junctions, whereas Rac stabilizes endothelial junctions and counteracts the effects of Rho. In this review, we present evidence for the opposing effects of these two regulatory proteins and discuss links between them and other key signalling molecules such as cyclic AMP (cAMP), cyclic GMP (cGMP), phosphatidylinositide 3-kinases (PI3Ks), mitogen-activated protein kinases (MAPKs), and protein kinases C (PKCs). We also discuss strategies for targeting Rho GTPase signalling in therapies for diseases involving altered endothelial permeability.
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Affiliation(s)
- Beata Wojciak-Stothard
- Ludwig Institute for Cancer Research, Royal Free and University College School of Medicine Branch, 91 Riding House Street, London W1W 7BS, UK.
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