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Azouz AA, Hanna DA, Abo-Saif AA, Anwar Shehata Messiha B. Interference with megalin expression/endocytic function by montelukast mitigates gentamicin nephrotoxicity: Downregulation of ClC-5 expression. Saudi Pharm J 2022; 30:150-161. [PMID: 35528850 PMCID: PMC9072701 DOI: 10.1016/j.jsps.2021.12.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/27/2021] [Indexed: 10/25/2022] Open
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Volume-regulated anion channel as a novel cancer therapeutic target. Int J Biol Macromol 2020; 159:570-576. [DOI: 10.1016/j.ijbiomac.2020.05.137] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/23/2020] [Accepted: 05/17/2020] [Indexed: 01/01/2023]
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Roles of volume-regulatory anion channels, VSOR and Maxi-Cl, in apoptosis, cisplatin resistance, necrosis, ischemic cell death, stroke and myocardial infarction. CURRENT TOPICS IN MEMBRANES 2019; 83:205-283. [DOI: 10.1016/bs.ctm.2019.03.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Hu C, Yang J, He Q, Luo Y, Chen Z, Yang L, Yi H, Li H, Xia H, Ran D, Yang Y, Zhang J, Li Y, Wang H. CysLTR1 Blockage Ameliorates Liver Injury Caused by Aluminum-Overload via PI3K/AKT/mTOR-Mediated Autophagy Activation in Vivo and in Vitro. Mol Pharm 2018; 15:1996-2006. [DOI: 10.1021/acs.molpharmaceut.8b00121] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Congli Hu
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Junqing Yang
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Qin He
- Department of Hepatobiliary Surgery, First Affiliated Hospital, Chongqing Medical University, Chongqing 400016, China
| | - Ying Luo
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Zhihao Chen
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Lu Yang
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Honggang Yi
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Huan Li
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Hui Xia
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Dongzhi Ran
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Yang Yang
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Jiahua Zhang
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Yuke Li
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
| | - Hong Wang
- Department of Pharmacology, Chongqing Medical University, the Key Laboratory of Biochemistry and Molecular Pharmacology, Chongqing 400016, China
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Bukiya AN, McMillan J, Liu J, Shivakumar B, Parrill AL, Dopico AM. Activation of calcium- and voltage-gated potassium channels of large conductance by leukotriene B4. J Biol Chem 2014; 289:35314-25. [PMID: 25371198 DOI: 10.1074/jbc.m114.577825] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcium/voltage-gated, large conductance potassium (BK) channels control numerous physiological processes, including myogenic tone. BK channel regulation by direct interaction between lipid and channel protein sites has received increasing attention. Leukotrienes (LTA4, LTB4, LTC4, LTD4, and LTE4) are inflammatory lipid mediators. We performed patch clamp studies in Xenopus oocytes that co-expressed BK channel-forming (cbv1) and accessory β1 subunits cloned from rat cerebral artery myocytes. Leukotrienes were applied at 0.1 nm-10 μm to either leaflet of cell-free membranes at a wide range of [Ca(2+)]i and voltages. Only LTB4 reversibly increased BK steady-state activity (EC50 = 1 nm; Emax reached at 10 nm), with physiological [Ca(2+)]i and voltages favoring this activation. Homomeric cbv1 or cbv1-β2 channels were LTB4-resistant. Computational modeling predicted that LTB4 docked onto the cholane steroid-sensing site in the BK β1 transmembrane domain 2 (TM2). Co-application of LTB4 and cholane steroid did not further increase LTB4-induced activation. LTB4 failed to activate β1 subunit-containing channels when β1 carried T169A, A176S, or K179I within the docking site. Co-application of LTB4 with LTA4, LTC4, LTD4, or LTE4 suppressed LTB4-induced activation. Inactive leukotrienes docked onto a portion of the site, probably preventing tight docking of LTB4. In summary, we document the ability of two endogenous lipids from different chemical families to share their site of action on a channel accessory subunit. Thus, cross-talk between leukotrienes and cholane steroids might converge on regulation of smooth muscle contractility via BK β1. Moreover, the identification of LTB4 as a highly potent ligand for BK channels is critical for the future development of β1-specific BK channel activators.
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Affiliation(s)
- Anna N Bukiya
- From the Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | - Jacob McMillan
- the Department of Chemistry and Computational Research on Materials Institute (CROMIUM), University of Memphis, Memphis, Tennessee 38152
| | - Jianxi Liu
- From the Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | - Bangalore Shivakumar
- From the Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | - Abby L Parrill
- the Department of Chemistry and Computational Research on Materials Institute (CROMIUM), University of Memphis, Memphis, Tennessee 38152
| | - Alex M Dopico
- From the Department of Pharmacology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
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op den Winkel M, Gmelin L, Schewe J, Leistner N, Bilzer M, Göke B, Gerbes AL, Steib CJ. Role of cysteinyl-leukotrienes for portal pressure regulation and liver damage in cholestatic rat livers. J Transl Med 2013; 93:1288-94. [PMID: 24061287 DOI: 10.1038/labinvest.2013.115] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 08/06/2013] [Accepted: 08/28/2013] [Indexed: 12/31/2022] Open
Abstract
Kupffer cells (KCs) have a major role in liver injury, and cysteinyl-leukotrienes (Cys-LTs) are known to be involved as well. The KC-mediated pathways for the production and secretion of Cys-LT in cholestatic liver injury have not yet been elucidated. Here, we hypothesized that KC activation by Toll-like receptor ligands results in Cys-LT-mediated microcirculatory alterations and liver injury in acute cholestasis. We hypothesized further that this situation is associated with changes in the secretion and production of Cys-LT. One week after bile duct ligation (BDL), livers showed typical histological signs of cholestatic liver injury. Associated microcirculatory disturbances caused increased basal and maximal portal pressure following KC activation. These differences were determined in BDL livers compared with sham-operated livers in vivo (KC activation by LPS 4 mg/kg b.w.) and in isolated perfused organs (KC activation by Zymosan A, 150 μg/ml). Treatment with the 5-lipoxygenase inhibitor MK-886 alone did not alter portal perfusion pressure, lactate dehydrogenase (LDH) efflux, or bile duct proliferation in BDL animals. Following KC activation, portal perfusion pressure increased. The degree of cell injury was attenuated by MK-886 (3 μM) treatment as estimated by LDH efflux. In normal rats, a large amount of Cys-LT efflux was found in the bile. Only a minor amount was found in the effluent perfusate. In BDL livers, the KC-mediated Cys-LT efflux into the sinusoidal system increased, although the absolute Cys-LT level was still grossly lower than the biliary excretion in sham-operated livers. In conclusion, our results indicate that treatment with Cys-LT inhibitors might be a relevant target for attenuating cholestatic liver damage.
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Affiliation(s)
- Mark op den Winkel
- Department of Medicine II, Hospital of the Ludwig-Maximilians University (LMU) of Munich, Campus Grosshadern, Munich, Germany
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Kose E, Sapmaz HI, Sarihan E, Vardi N, Turkoz Y, Ekinci N. Beneficial effects of montelukast against methotrexate-induced liver toxicity: a biochemical and histological study. ScientificWorldJournal 2012; 2012:987508. [PMID: 22566785 PMCID: PMC3329899 DOI: 10.1100/2012/987508] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 01/12/2012] [Indexed: 01/16/2023] Open
Abstract
The effects of montelukast against methotrexate-induced liver damage were investigated. 35 Wistar albino female rats were divided into 5 groups as follows: group I: control; group II: montelukast (ML); group III: methotrexate (Mtx); group IV: montelukast treatment after methotrexate application (Mtx + ML); group V: montelukast treatment before methotrexate application (ML + Mtx). At the end of the experiment, the liver tissues of rats were removed. Malondialdehyde (MDA), myeloperoxidase (MPO), and reduced glutathione levels were determined from liver tissues. In addition, the liver tissues were examined histologically. MDA and MPO levels of Mtx group were significantly increased when compared to control group. In Mtx + ML group, these parameters were decreased as compared to Mtx group. Mtx injection exhibited major histological alterations such as eosinophilic staining and swelling of hepatocytes. The glycogen storage in hepatocytes was observed as decreased by periodic acid schiff staining in Mtx group as compared to controls. ML treatment did not completely ameliorate the lesions and milder degenerative alterations as loss of the glycogen content was still present. It was showed that montelukast treatment after methotrexate application could reduce methotrexate-induced experimental liver damage.
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Affiliation(s)
- Evren Kose
- Department of Anatomy, School of Medicine, İnonu University Medical Faculty, 44280 Malatya, Turkey.
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Cuciureanu M, Căruntu ID, Păduraru O, Stoica B, Jerca L, Crauciuc E, Nechifor M. The protective effect of montelukast sodium on carbon tetrachloride induced hepatopathy in rat. Prostaglandins Other Lipid Mediat 2008; 88:82-8. [PMID: 19041730 DOI: 10.1016/j.prostaglandins.2008.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 10/21/2008] [Accepted: 10/30/2008] [Indexed: 01/09/2023]
Abstract
AIM This study investigates the effects of montelukast sodium (MK) (CysLTLT1 receptor antagonist) on CCl(4)induced hepatopathy on rat. MATERIAL AND METHODS We worked on 4 groups of 10 Wistar male rats each. The groups received as follows: group I (control group) - saline, group II - MK 5mg/kg/day i.p. for 5 days, group III - MK 5mg/kg/day i.p., 1 day prior to and 4 days concomitantly with CCl(4) p.o., 0.3ml/Kg/day and group IV - CCl(4), p.o., 0.3ml/Kg/day for 4 days. One day after the last administration, samples of blood were taken and alanine aminotransferase (ALT), total bilirubin (TB), direct bilirubin (DB), malondialdehyde (MDA), catalase (CAT) as well as total antioxidant capacity (TAC) were determined. The histopathological exam was performed. We also determined superoxide dismutase (SOD), MDA, CAT and GSH in liver homogenate. RESULTS Compared to group IV, group III exhibited statistically significant lower levels of ALT (318+/-15.75 versus 203.14+/-10.28 UI, p<0.0001), TB (3.16+/-0.30 versus 1.99+/-0.08mg/dl, p<0.0001), MDA in blood and in liver homogenate (4.98+/-1.71 versus 2.15+/-1.18nmol/ml, p=0.0004) and higher levels of SOD and CAT. Histopathologically, group IV presented important macro- and micro-vesicular hepatic steatosis and group III preserved lobular histoarchitecture and had less severe cellular lesions. CONCLUSION MK exhibits a partial hepatoprotective effect on rats treated with CCl(4).
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Affiliation(s)
- Magdalena Cuciureanu
- Department of Pharmacology, University of Medicine and Pharmacy, GRIGORE T. POPA, IASI, Romania.
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Okada Y, Shimizu T, Maeno E, Tanabe S, Wang X, Takahashi N. Volume-sensitive chloride channels involved in apoptotic volume decrease and cell death. J Membr Biol 2006; 209:21-9. [PMID: 16685598 DOI: 10.1007/s00232-005-0836-6] [Citation(s) in RCA: 189] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Indexed: 11/30/2022]
Abstract
Apoptosis is an essential process in organ development, tissue homeostasis, somatic cell turnover, and the pathogenesis of degenerative diseases. Apoptotic cell death occurs in response to a variety of stimuli in physiological and pathological circumstances. Efflux of K(+) and Cl(-) leads to apoptotic volume decrease (AVD) of the cell. Both mitochondrion-mediated intrinsic, and death receptor-mediated extrinsic, apoptotic stimuli have been reported to rapidly activate Cl(-) conductances in a large variety of cell types. In epithelial cells and cardiomyocytes, the AVD-inducing anion channel was recently determined to be the volume-sensitive outwardly rectifying (VSOR) Cl(-) channel which is usually activated by swelling under non-apoptotic conditions. Blocking the VSOR Cl(-) channel prevented cell death in not only epithelial and cardiac cells, but also other cell types, by inhibiting the induction of AVD and subsequent apoptotic events. Ischemia-reperfusion-induced apoptotic death in cardiomyocytes and brain neurons was also prevented by Cl(-) channel blockers. Furthermore, cancer cell apoptosis induced by the anti-cancer drug cisplatin was recently found to be associated with augmented activity of the VSOR Cl(-) channel and to be inhibited by a Cl(-) channel blocker. The apoptosis-inducing VSOR Cl(-) channel is distinct from ClC-3 and its molecular identity remains to be determined.
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Affiliation(s)
- Y Okada
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan.
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Franco R, Bortner CD, Cidlowski JA. Potential Roles of Electrogenic Ion Transport and Plasma Membrane Depolarization in Apoptosis. J Membr Biol 2006; 209:43-58. [PMID: 16685600 DOI: 10.1007/s00232-005-0837-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2005] [Indexed: 12/15/2022]
Abstract
Apoptosis is characterized by the programmed activation of specific biochemical pathways leading to the organized demise of cells. To date, aspects of the intracellular signaling machinery involved in this phenomenon have been extensively dissected and characterized. However, recent studies have elucidated a novel role for changes in the intracellular milieu of the cells as important modulators of the cell death program. Specially, intracellular ionic homeostasis has been reported to be a determinant in both the activation and progression of the apoptotic cascade. Several apoptotic insults trigger specific changes in ionic gradients across the plasma membrane leading to depolarization of the plasma membrane potential (PMP). These changes lead to ionic imbalance early during apoptosis. Several studies have also suggested the activation and/or modulation of specific ionic transport mechanisms including ion channels, transporters and ATPases, as mediators of altered intracellular ionic homeostasis leading to PMP depolarization during apoptosis. However, the role of PMP depolarization and of the changes in ionic homeostasis during the progression of apoptosis are still unclear. This review summarizes the current knowledge regarding the causes and consequences of PMP depolarization during apoptosis. We also review the potential electrogenic ion transport mechanisms associated with this event, including the net influx/efflux of cations and anions. An understanding of these mechamisms could lead to the generation of new therapeutic approaches for a variety of diseases involving apoptosis.
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Affiliation(s)
- R Franco
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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d'Anglemont de Tassigny A, Souktani R, Ghaleh B, Henry P, Berdeaux A. Structure and pharmacology of swelling-sensitive chloride channels, I(Cl,swell). Fundam Clin Pharmacol 2004; 17:539-53. [PMID: 14703715 DOI: 10.1046/j.1472-8206.2003.00197.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Since several years, the interest for chloride channels and more particularly for the enigmatic swelling-activated chloride channel (I(Cl,swell)) is increasing. Despite its well-characterized electrophysiological properties, the I(Cl,swell) structure and pharmacology are not totally elucidated. These channels are involved in a variety of cell functions, such as cardiac rhythm, cell proliferation and differentiation, cell volume regulation and cell death through apoptosis. This review will consider different aspects regarding structure, electrophysiological properties, pharmacology, modulation and functions of these swelling-activated chloride channels.
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Okada Y, Maeno E, Shimizu T, Manabe K, Mori SI, Nabekura T. Dual roles of plasmalemmal chloride channels in induction of cell death. Pflugers Arch 2004; 448:287-95. [PMID: 15103464 DOI: 10.1007/s00424-004-1276-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 03/04/2004] [Indexed: 10/26/2022]
Abstract
Even under anisotonic conditions, most cells can regulate their volume by mechanisms called regulatory volume decrease (RVD) and increase (RVI) after osmotic swelling or shrinkage, respectively. In contrast, the initial processes of necrosis and apoptosis are associated with persistent swelling and shrinkage. Necrotic volume increase (NVI) is initiated by uptake of osmolytes, such as Na+, Cl- and lactate, under conditions of injury, hypoxia, ischaemia, acidosis or lactacidosis. Persistence of NVI is caused by dysfunction of RVD due to impairment of volume-sensitive Cl- channels under conditions of ATP deficiency or lactacidosis. Both lactacidosis-induced RVD dysfunction and necrotic cell death are prevented by pretreatment of cells with the vacuolating cytotoxin-A (VacA) toxin protein purified from Helicobacter pylori, which forms a lactacidosis-resistant anion channel. Apoptotic volume decrease (AVD) is triggered by activation of K+ and Cl- conductances following stimulation with a mitochondrion-mediated or death receptor-mediated apoptosis inducer. Apoptotic cell death can be prevented by blocking the Cl- channels but not the K+-Cl- cotransporters. Thus, the volume regulatory anion channel plays, unless impaired, a cell-rescuing role in the necrotic process by ensuring RVD after swelling induced by necrotic insults, whereas normotonic activation of the anion channel plays a cell-killing role in the apoptotic process by triggering AVD following stimulation with apoptosis inducers.
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Affiliation(s)
- Yasunobu Okada
- Department of Cell Physiology, National Institute for Physiological Sciences, 444-8585 Okazaki, Japan.
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Abstract
Adenosine triphosphate binding cassette family transport proteins are important organic ion transporters in hepatocytes but these molecules may also exhibit other functions. In the present study we have measured the effects of substrates of the canalicular organic ion transporter multidrug resistance associated protein 2 (Mrp2) on chloride channel activation and cell volume regulation. We found that substrates such as leukotriene D(4), 17-beta-estradiol glucuronide, and the leukotriene inhibitor MK-571 accelerated the activation of chloride channels by cell swelling and activated chloride channels in cytokine-pretreated hepatocytes. Two conjugated estrogens that are not Mrp2 substrates did not produce this effect. Hepatocytes derived from a strain of transport-deficient rats (TR(-)), which lack Mrp2 expression, showed none of these substrate effects. Coincident with their ability to activate channels, the Mrp2 substrates increased the rate of volume regulatory decrease by approximately 50% (P <.01), confirming that enhanced channel activation under this condition stimulated volume regulation. In TR-hepatocytes the Mrp2 substrate had no effect on volume regulation. In conclusion, Mrp2 plays a role in regulation of chloride channel function by reducing the lag time necessary for channel activation and consequently accelerating the process of cell volume regulation. Substrates of Mrp2 affect the ability of the protein to interact with chloride channels. These findings represent an alternative function of Mrp2 in hepatocytes.
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Affiliation(s)
- Xinhua Li
- Department of Physiology and Biophysics, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0641, USA
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Abstract
Hepatocytes possess chloride channels at the plasma membrane and in multiple intracellular compartments. These channels are required for cell volume regulation and acidification of intracellular organelles. Evidence also supports a role of chloride channels in modulation of apoptosis and cell growth. Swelling- and Ca(2+)-activated chloride channels have been identified in hepatocyte plasma membranes, and chloride channels have been observed in the membranes of lysosomes, endosomes, Golgi, endoplasmic reticulum, mitochondria, and the nucleus. This review summarizes the functions of these channels and discusses the specific channel molecules they may represent. Chloride channel molecules shown to be expressed in hepatocytes include members of the ClC channel family (ClC-2, ClC-3, ClC-5, and ClC-7), members of the newly identified CLIC family of intracellular chloride channels (CLIC-1 and CLIC-4), the mitochondrial voltage-dependent anion channel, and a newly identified intracellular channel, MCLC (Mid-1 related chloride channel). Current understanding does not include a molecular identification of most of the observed channel functions, but details of the molecular properties of these channel molecules should allow future identification and further understanding of chloride channel function in hepatocytes.
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Affiliation(s)
- Xinhua Li
- Department of Physiology and Biophysics University of Texas Medical Branch, Galveston, Texas 77555-0641, USA.
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Feihl F, Waeber B, Liaudet L. Is nitric oxide overproduction the target of choice for the management of septic shock? Pharmacol Ther 2001; 91:179-213. [PMID: 11744067 DOI: 10.1016/s0163-7258(01)00155-3] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Sepsis is a heterogeneous class of syndromes caused by a systemic inflammatory response to infection. Septic shock, a severe form of sepsis, is associated with the development of progressive damage in multiple organs, and is a leading cause of patient mortality in intensive care units. Despite important advances in understanding its pathophysiology, therapy remains largely symptomatic and supportive. A decade ago, the overproduction of nitric oxide (NO) had been discovered as a potentially important event in this condition. As a result, great hopes arose that the pharmacological inhibition of NO synthesis could be developed into an efficient, mechanism-based therapeutic approach. Since then, an extraordinary effort by the scientific community has brought a deeper insight regarding the feasibility of this goal. Here we present in summary form the present state of knowledge of the biological chemistry and physiology of NO. We then proceed to a systematic review of experimental and clinical data, indicating an up-regulation of NO production in septic shock; information on the role of NO in septic shock, as provided by experiments in transgenic mice that lack the ability to up-regulate NO production; effects of pharmacological inhibitors of NO production in various experimental models of septic shock; and relevant clinical experience. The accrued evidence suggests that the contribution of NO to the pathophysiology of septic shock is highly heterogeneous and, therefore, difficult to target therapeutically without appropriate monitoring tools, which do not exist at present.
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Affiliation(s)
- F Feihl
- Division of Pathophysiology and Medical Teaching, Department of Internal Medicine, University Hospital, PPA, BH19-317, CHUV, CH 1011 Lausanne, Switzerland.
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Okada Y, Maeno E, Shimizu T, Dezaki K, Wang J, Morishima S. Receptor-mediated control of regulatory volume decrease (RVD) and apoptotic volume decrease (AVD). J Physiol 2001; 532:3-16. [PMID: 11283221 PMCID: PMC2278524 DOI: 10.1111/j.1469-7793.2001.0003g.x] [Citation(s) in RCA: 399] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2001] [Accepted: 01/30/2001] [Indexed: 01/31/2023] Open
Abstract
A fundamental property of animal cells is the ability to regulate their own cell volume. Even under hypotonic stress imposed by either decreased extracellular or increased intracellular osmolarity, the cells can re-adjust their volume after transient osmotic swelling by a mechanism known as regulatory volume decrease (RVD). In most cell types, RVD is accomplished mainly by KCl efflux induced by parallel activation of K+ and Cl- channels. We have studied the molecular mechanism of RVD in a human epithelial cell line (Intestine 407). Osmotic swelling results in a significant increase in the cytosolic Ca2+ concentration and thereby activates intermediate-conductance Ca2+-dependent K+ (IK) channels. Osmotic swelling also induces ATP release from the cells to the extracellular compartment. Released ATP stimulates purinergic ATP (P2Y2) receptors, thereby inducing phospholipase C-mediated Ca2+ mobilization. Thus, RVD is facilitated by stimulation of P2Y2 receptors due to augmentation of IK channels. In contrast, stimulation of another G protein-coupled Ca2+-sensing receptor (CaR) enhances the activity of volume-sensitive outwardly rectifying Cl- channels, thereby facilitating RVD. Therefore, it is possible that Ca2+ efflux stimulated by swelling-induced and P2Y2 receptor-mediated intracellular Ca2+ mobilization activates the CaR, thereby secondarily upregulating the volume-regulatory Cl- conductance. On the other hand, the initial process towards apoptotic cell death is coupled to normotonic cell shrinkage, called apoptotic volume decrease (AVD). Stimulation of death receptors, such as TNF receptor and Fas, induces AVD and thereafter biochemical apoptotic events in human lymphoid (U937), human epithelial (HeLa), mouse neuroblastoma x rat glioma hybrid (NG108-15) and rat phaeochromocytoma (PC12) cells. In those cells exhibiting AVD, facilitation of RVD is always observed. Both AVD induction and RVD facilitation as well as succeeding apoptotic events can be abolished by prior treatment with a blocker of volume-regulatory K+ or Cl- channels, suggesting that AVD is caused by normotonic activation of ion channels that are normally involved in RVD under hypotonic conditions. Therefore, it is likely that G protein-coupled receptors involved in RVD regulation and death receptors triggering AVD may share common downstream signals which should give us key clues to the detailed mechanisms of volume regulation and survival of animal cells. In this Topical Review, we look at the physiological ionic mechanisms of cell volume regulation and cell death-associated volume changes from the facet of receptor-mediated cellular processes.
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Affiliation(s)
- Y Okada
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan.
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McMahon B, Stenson C, McPhillips F, Fanning A, Brady HR, Godson C. Lipoxin A4 antagonizes the mitogenic effects of leukotriene D4 in human renal mesangial cells. Differential activation of MAP kinases through distinct receptors. J Biol Chem 2000; 275:27566-75. [PMID: 10869343 DOI: 10.1074/jbc.m001015200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The lipoxygenase-derived eicosanoids leukotrienes and lipoxins are well defined regulators of hemeodynamics and leukocyte recruitment in inflammatory conditions. Here, we describe a novel bioaction of lipoxin A(4) (LXA(4)), namely inhibition of leukotriene D(4) (LTD(4))-induced human renal mesangial cell proliferation, and investigate the signal transduction mechanisms involved. LXA(4) blocked LTD(4)-stimulated phosphatidylinositol 3-kinase (PI 3-kinase) activity in parallel to inhibition of LTD(4)-induced mesangial cell proliferation. Screening of a human mesangial cell cDNA library revealed expression of the recently described cys-leukotriene(1)/LTD(4) receptor. LTD(4)-induced mesangial cell proliferation required both extracellular-related signal regulated kinase (erk) and PI 3-kinase activation and may involve platelet-derived growth factor receptor transactivation. LTD(4)-stimulated the MAP kinases erk and p38 via a pertussis toxin (PTX)-sensitive pathway dependent on PI 3-kinase and protein kinase C activation. On screening a cDNA library, mesangial cells were found to express the previously described LXA(4) receptor. In contrast to LTD(4), LXA(4) showed differential activation of erk and p38. LXA(4) activation of erk was insensitive to PTX and PI 3-kinase inhibition, whereas LXA(4) activation of p38 was sensitive to PTX and could be blocked by the LTD(4) receptor antagonist SKF 104353. These data suggest that LXA(4) stimulation of the MAP kinase superfamily involves two distinct receptors: one shared with LTD(4) and coupled to a PTX-sensitive G protein (G(i)) and a second coupled via an alternative G protein, such as G(q) or G(12), to erk activation. These data expand on the spectrum of LXA(4) bioactions within an inflammatory milieu.
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Affiliation(s)
- B McMahon
- Centre for Molecular Inflammation and Vascular Research, Department of Medicine and Therapeutics, Mater Misericordiae Hospital and the Conway Institute of Biomolecular and Biomedical Research, University College Dublin, 41 Eccles St., Dublin 7, Ireland
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Shimada K, Navarro J, Goeger DE, Mustafa SB, Weigel PH, Weinman SA. Expression and regulation of leukotriene-synthesis enzymes in rat liver cells. Hepatology 1998; 28:1275-81. [PMID: 9794912 DOI: 10.1002/hep.510280516] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
The liver plays a major role in metabolism and elimination of leukotrienes (LT). It produces cysteinyl leukotrienes (cLT), and cLT have been implicated in hepatocellular toxicity in several models of lipopolysaccharide (LPS)-associated liver injury. However, the liver cell types responsible for cLT production are poorly defined, and the expression of the LT-synthesis enzymes, 5-lipoxygenase (5-LO) and LTC4 synthase (LTC4-S), in liver cells has never been demonstrated. The aim of the present study was to examine the ability of rat liver cells to produce cLT by determining whether hepatocytes, Kupffer cells, and sinusoidal endothelial cells express mRNA and enzyme activities of the LT-synthesis enzymes and whether expression is altered by LPS. 5-LO mRNA was expressed in whole liver, and expression was enhanced by LPS. Cell fractionation studies demonstrated that expression was present in Kupffer cells and sinusoidal endothelial cells, but not in hepatocytes. LTC4-S mRNA was detected in whole liver, hepatocytes, and sinusoidal endothelial cells, but not in Kupffer cells. Semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR) showed that LPS increased LTC4-S expression in hepatocytes by a factor of 3 (n = 3; P < .03). LTC4-S enzyme activity in the microsomal fraction of hepatocytes was also increased from 0.52 +/- 0.13 to 1.90 +/- 0.66 nmol . mg protein-1 . 5 min-1 (n = 6; P < .015) after LPS treatment. These results indicate that hepatocytes do not possess the ability for de novo synthesis of cLT from arachidonic acid, but they may actively participate in cLT production by conjugation of LTA4 with glutathione to produce LTC4. LPS enhances LTC4-S expression in hepatocytes. This intrinsic cLT production may contribute to hepatocellular injury during inflammation.
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Affiliation(s)
- K Shimada
- Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston, TX, USA
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