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Vu K, Blumwald E, Gelli A. The Antifungal Activity of HMA, an Amiloride Analog and Inhibitor of Na +/H + Exchangers. Front Microbiol 2021; 12:673035. [PMID: 34025629 PMCID: PMC8133316 DOI: 10.3389/fmicb.2021.673035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/12/2021] [Indexed: 11/13/2022] Open
Abstract
One path toward identifying effective and easily accessible antifungals is to repurpose commonly used drugs. Amiloride, a widely used diuretic, inhibits different isoforms of Na+/H+ exchangers, Na+ channels, and Na+/Ca2+ exchangers. Here, we found that amiloride had poor antifungal activity against isolates of Cryptococcus prompting the examination of the amiloride analog, HMA [5-(N,N-hexamethylene)amiloride]. HMA possesses strong activity against Na+/H+ exchangers (NHEs) and little K+-associated toxicity since HMA has only minimal inhibitory effects toward epithelial sodium channels (ENaC), the diuretic and antikaliuretic target of amiloride. Although HMA produced a robust dose-dependent growth inhibition of several fungal isolates, susceptibility assays revealed modest MICs against isolates of Cryptococcus. A checkerboard dilution strategy resulted in fractional inhibitory concentrations (FIC) < 0.5, suggesting that HMA displays synergy with several antifungal azole drugs including posaconazole, voriconazole, and ketoconazole. Itraconazole and ravuconazole showed moderate synergy with HMA across all tested fungal isolates. In combination with HMA, ravuconazole had MICs of 0.004-0.008 μg/ml, a ∼16-fold reduction compared to MICs of ravuconazole when used alone and significantly more effective than the overall MIC90 (0.25 μg/ml) reported for ravuconazole against 541 clinical isolates of Cryptococcus neoformans. In combination with azole drugs, MICs of HMA ranged from 3.2 μM (1 μg/ml) to 26 μM (16 μg/ml), HMA was not cytotoxic at concentrations ≤ 8 μg/ml, but MICs were above the reported HMA Ki of 0.013-2.4 μM for various Na+/H+ exchangers. Our results suggest that HMA has limited potential as a monotherapy and may have additional targets in fungal/yeast cells since strains lacking NHEs remained sensitive to HMA. We determined that the hydrophobic substituent at the 5-amino group of HMA is likely responsible for the observed antifungal activity and synergy with several azoles since derivatives with bulky polar substitutions showed no activity against Cryptococcus, indicating that other 5-substituted HMA derivatives could possess stronger antifungal activity. Moreover, substitution of other positions around the pyrazine core of HMA has not been investigated but could reveal new leads for antifungal drug development.
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Affiliation(s)
- Kiem Vu
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, United States
| | - Eduardo Blumwald
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Angie Gelli
- Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, United States
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2
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Patwardhan NN, Ganser LR, Kapral GJ, Eubanks CS, Lee J, Sathyamoorthy B, Al-Hashimi HM, Hargrove AE. Amiloride as a new RNA-binding scaffold with activity against HIV-1 TAR. MEDCHEMCOMM 2017; 8:1022-1036. [PMID: 28798862 PMCID: PMC5546750 DOI: 10.1039/c6md00729e] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 03/14/2017] [Indexed: 12/23/2022]
Abstract
Diversification of RNA-targeted scaffolds offers great promise in the search for selective ligands of therapeutically relevant RNA such as HIV-1 TAR. We herein report the establishment of amiloride as a novel RNA-binding scaffold along with synthetic routes for combinatorial C(5)- and C(6)-diversification. Iterative modifications at the C(5)- and C(6)- positions yielded derivative 24, which demonstrated a 100-fold increase in activity over the parent dimethylamiloride in peptide displacement assays. NMR chemical shift mapping was performed using the 2D SOFAST- [1H-13C] HMQC NMR method, which allowed for facile and rapid evaluation of binding modes for all library members. Cheminformatic analysis revealed distinct differences between selective and non-selective ligands. In this study, we evolved dimethylamiloride from a weak TAR ligand to one of the tightest binding selective TAR ligands reported to date through a novel combination of synthetic methods and analytical techniques. We expect these methods to allow for rapid library expansion and tuning of the amiloride scaffold for a range of RNA targets and for SOFAST NMR to allow unprecedented evaluation of small molecule:RNA interactions.
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Affiliation(s)
- Neeraj N. Patwardhan
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
| | - Laura R. Ganser
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Gary J. Kapral
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
| | - Christopher S. Eubanks
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
| | - Janghyun Lee
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Bharathwaj Sathyamoorthy
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Hashim M. Al-Hashimi
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
| | - Amanda E. Hargrove
- Department of Chemistry
, Duke University
,
Durham
, North Carolina 27708
, USA
.
; Tel: +1 919 660 1522
- Department of Biochemistry
, Duke University Medical Center
,
Durham
, North Carolina 27708
, USA
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3
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Pasupuleti N, Grodzki AC, Gorin F. Mis-trafficking of endosomal urokinase proteins triggers drug-induced glioma nonapoptotic cell death. Mol Pharmacol 2015; 87:683-96. [PMID: 25634671 DOI: 10.1124/mol.114.096602] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
5-Benzylglycinyl-amiloride (UCD38B) is the parent molecule of a class of anticancer small molecules that kill proliferative and nonproliferative high-grade glioma cells by programmed necrosis. UCD38B intracellularly triggers endocytosis, causing 40-50% of endosomes containing proteins of the urokinase plasminogen activator system (uPAS) to relocate to perinuclear mitochondrial regions. Endosomal "mis-trafficking" caused by UCD38B in human glioma cells corresponds to mitochondrial depolarization with the release and nuclear translocation of apoptotis-inducing factor (AIF) followed by irreversible caspase-independent cell demise. High-content quantification of immunocytochemical colocalization studies identified that UCD38B treatment increased endocytosis of the urokinase plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitor-1 (PAI-1) into the early and late endosomes by 4- to 5-fold prior to AIF nuclear translocation and subsequent glioma demise. PAI-1 was found to comparably relocate with a subset of early and late endosomes in four different human glioma cell lines after UCD38B treatment, followed by caspase-independent, nonapoptotic cell death. Following UCD38B treatment, the receptor guidance protein LRP-1, which is required for endosomal recycling of the uPA receptor to the plasmalemma, remained abnormally associated with PAI-1 in early and late endosomes. The resultant aberrant endosomal recycling increased the total cellular content of the uPA-PAI-1 protein complex. Reversible inhibition of cellular endocytosis demonstrated that UCD38B bypasses the plasmalemmal uPAS complex and directly acts intracellularly to alter uPAS endocytotic trafficking. UCD38B represents a class of small molecules whose anticancer cytotoxicity is a consequence of causing the mis-trafficking of early and late endosomes containing uPAS cargo and leading to AIF-mediated necrotic cell death.
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Affiliation(s)
- Nagarekha Pasupuleti
- Department of Neurology, School of Medicine (N.P., F.G.), and Department of Molecular Biosciences, School of Veterinary Medicine (N.P., A.C.G., F.G.), University of California, Davis, California
| | - Ana Cristina Grodzki
- Department of Neurology, School of Medicine (N.P., F.G.), and Department of Molecular Biosciences, School of Veterinary Medicine (N.P., A.C.G., F.G.), University of California, Davis, California
| | - Fredric Gorin
- Department of Neurology, School of Medicine (N.P., F.G.), and Department of Molecular Biosciences, School of Veterinary Medicine (N.P., A.C.G., F.G.), University of California, Davis, California
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Leon LJ, Pasupuleti N, Gorin F, Carraway KL. A cell-permeant amiloride derivative induces caspase-independent, AIF-mediated programmed necrotic death of breast cancer cells. PLoS One 2013; 8:e63038. [PMID: 23646172 PMCID: PMC3639988 DOI: 10.1371/journal.pone.0063038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 03/27/2013] [Indexed: 12/19/2022] Open
Abstract
Amiloride is a potassium-sparing diuretic that has been used as an anti-kaliuretic for the chronic management of hypertension and heart failure. Several studies have identified a potential anti-cancer role for amiloride, however the mechanisms underlying its anti-tumor effects remain to be fully delineated. Our group previously demonstrated that amiloride triggers caspase-independent cytotoxic cell death in human glioblastoma cell lines but not in primary astrocytes. To delineate the cellular mechanisms underlying amiloride’s anti-cancer cytotoxicity, cell permeant and cell impermeant derivatives of amiloride were synthesized that exhibit markedly different potencies in cancer cell death assays. Here we compare the cytotoxicities of 5-benzylglycinyl amiloride (UCD38B) and its free acid 5-glycinyl amiloride (UCD74A) toward human breast cancer cells. UCD74A exhibits poor cell permeability and has very little cytotoxic activity, while UCD38B is cell permeant and induces the caspase-independent death of proliferating and non-proliferating breast cancer cells. UCD38B treatment of human breast cancer cells promotes autophagy reflected in LC3 conversion, and induces the dramatic swelling of the endoplasmic reticulum, however these events do not appear to be the cause of cell death. Surprisingly, UCD38B but not UCD74A induces efficient AIF translocation from the mitochondria to the nucleus, and AIF function is necessary for the efficient induction of cancer cell death. Our observations indicate that UCD38B induces programmed necrosis through AIF translocation, and suggest that its cytosolic accessibility may facilitate drug action.
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Affiliation(s)
- Leonardo J. Leon
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California, United States of America
- UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, California, United States of America
| | - Nagarekha Pasupuleti
- Department of Neurology, UC Davis School of Medicine, Sacramento, California, United States of America
| | - Fredric Gorin
- Department of Neurology, UC Davis School of Medicine, Sacramento, California, United States of America
- UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, California, United States of America
| | - Kermit L. Carraway
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California, United States of America
- UC Davis Comprehensive Cancer Center, UC Davis School of Medicine, Sacramento, California, United States of America
- * E-mail:
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Pasupuleti N, Leon L, Carraway KL, Gorin F. 5-Benzylglycinyl-amiloride kills proliferating and nonproliferating malignant glioma cells through caspase-independent necroptosis mediated by apoptosis-inducing factor. J Pharmacol Exp Ther 2012; 344:600-15. [PMID: 23241369 DOI: 10.1124/jpet.112.200519] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
5'-Βenzylglycinyl-amiloride (UCD38B) and glycinyl-amiloride (UCD74A) are cell-permeant and cell-impermeant derivatives of amiloride, respectively, and used here to identify the cellular mechanisms of action underlying their antiglioma effects. UCD38B comparably kills proliferating and nonproliferating gliomas cells when cell cycle progression is arrested either by cyclin D1 siRNA or by acidification. Cell impermeant UCD74A inhibits plasmalemmal urokinase plasminogen activator (uPA) and the type 1 sodium-proton exchanger with potencies analogous to UCD38B, but is cytostatic. In contrast, UCD38B targets intracellular uPA causing mistrafficking of uPA into perinuclear mitochondria, reducing the mitochondrial membrane potential, and followed by the release of apoptotic inducible factor (AIF). AIF nuclear translocation is followed by a caspase-independent necroptotic cell death. Reduction in AIF expression by siRNA reduces the antiglioma cytotoxic effects of UCD38B, while not activating the caspase pathway. Ultrastructural changes shortly following treatment with UCD38B demonstrate dilation of endoplasmic reticulum (ER) and mitochondrial swelling followed by nuclear condensation within hours consistent with a necroptotic cell death differing from apoptosis and from autophagy. These drug mechanism of action studies demonstrate that UCD38B induces a cell cycle-independent, caspase-independent necroptotic glioma cell death that is mediated by AIF and independent of poly (ADP-ribose) polymerase and H2AX activation.
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Affiliation(s)
- Nagarekha Pasupuleti
- Department of Neurology, School of Medicine, University of California, Davis, CA, USA
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6
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Possible implications of acid-sensing ion channels in ischemia-induced retinal injury in rats. Jpn J Ophthalmol 2012; 57:120-5. [PMID: 23152156 DOI: 10.1007/s10384-012-0213-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 09/21/2012] [Indexed: 12/21/2022]
Abstract
BACKGROUND Retinal ischemia in eyes with diabetic retinopathy and retinal vein occlusion leads to local tissue acidosis. Acid-sensing ion channels (ASICs) are expressed in photoreceptors and other neurons in the retina, and may play a role in acid-induced cell injury. The purpose of this study was to investigate the neuroprotective effects of amiloride, an ASIC blocker, on induced retinal ischemia in rats. METHODS Transient retinal ischemia was induced in male Long-Evans rats by the temporary ligation of the optic nerve. Just before the induction of ischemia, the experimental eyes underwent intravitreal injection of amiloride. On day 7, the retinal damage in eyes that underwent amiloride treatment (and in those that did not undergo the treatment) was evaluated by histology and electroretinogram (ERG). RESULTS Transient retinal ischemia caused retinal degeneration with thinning of the inner layer of the retina. The blockage of ASICs with amiloride significantly prevented retinal degeneration. ERG demonstrated that the reduction in a- and b-wave amplitudes induced by the transient retinal ischemia was significantly prevented by the application of amiloride. CONCLUSIONS The present study suggests that ASICs might, at least in part, play a pathophysiological role in ischemia-induced neurodegeneration. Blockage of ASICs may have a potential neuroprotective effect in ocular ischemic diseases.
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7
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Massey AP, Harley WR, Pasupuleti N, Gorin FA, Nantz MH. 2-Amidino analogs of glycine-amiloride conjugates: inhibitors of urokinase-type plasminogen activator. Bioorg Med Chem Lett 2012; 22:2635-9. [PMID: 22366654 DOI: 10.1016/j.bmcl.2011.12.123] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 12/23/2011] [Accepted: 12/27/2011] [Indexed: 10/14/2022]
Abstract
The relative non-toxicity of the diuretic amiloride, coupled with its selective inhibition of the protease urokinase plasminogen activator (uPA), makes this compound class attractive for structure-activity studies. Herein we substituted the C(2)-acylguanidine of C(5)-glycyl-amiloride with amidine and amidoxime groups. The data show the importance of maintaining C(5)-hydrophobicity. The C(5)-benzylglycine analogs containing either C(2)-acylguanidine or amidine inhibited uPA with an IC(50) ranging from 3 to 7 μM and were cytotoxic to human U87 malignant glioma cells.
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Affiliation(s)
- Archna P Massey
- Department of Chemistry, University of Louisville, Louisville, KY 40292, USA
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8
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Jancic CC, Cabrini M, Gabelloni ML, Rodríguez Rodrigues C, Salamone G, Trevani AS, Geffner J. Low extracellular pH stimulates the production of IL-1β by human monocytes. Cytokine 2011; 57:258-68. [PMID: 22154780 DOI: 10.1016/j.cyto.2011.11.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 10/06/2011] [Accepted: 11/17/2011] [Indexed: 10/14/2022]
Abstract
The development of acidic environments is a hallmark of inflammatory processes of different etiology. We have previously shown that transient exposure to acidic conditions, similar to those encountered in vivo, induces the activation of neutrophils and the phenotypic maturation of dendritic cells. We here report that extracellular acidosis (pH 6.5) selectively stimulates the production and the secretion of IL-1β by human monocytes without affecting the production of TNF-α, IL-6 and the expression of CD40, CD80, CD86, and HLA-DR. Stimulation of IL-1β production by pH 6.5-treated monocytes was shown to be dependent on caspase-1 activity, and it was also observed using peripheral blood mononuclear cells instead of isolated monocytes. Contrasting with the results in monocytes, we found that pH 6.5 did not stimulate any production of IL-1β by macrophages. Changes in intracellular pH seem to be involved in the stimulation of IL-1β production. In fact, monocytes cultured at pH 6.5 undergo a fall in the values of intracellular pH while the inhibitor of the Na+/H+ exchanger, 5-(N-ethyl-N-isopropyl)amiloride induced both, a decrease in the values of intracellular pH and the stimulation of IL-1β production. Real time quantitative PCR assays indicated that monocytes cultured either at pH 6.5 or in the presence of 5-(N-ethyl-N-isopropyl)amiloride expressed higher levels of pro-IL-1β mRNA suggesting that low values of intracellular pH enhance the production of IL-1β, at least in part, by stimulating the synthesis of its precursor.
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Affiliation(s)
- Carolina Cristina Jancic
- Instituto de Investigaciones Hematológicas (IIHEMA), Academia Nacional de Medicina, Buenos Aires, Argentina.
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Radhakrishnan J, Kolarova JD, Ayoub IM, Gazmuri RJ. AVE4454B--a novel sodium-hydrogen exchanger isoform-1 inhibitor--compared less effective than cariporide for resuscitation from cardiac arrest. Transl Res 2011; 157:71-80. [PMID: 21256459 PMCID: PMC3651912 DOI: 10.1016/j.trsl.2010.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 11/12/2010] [Accepted: 11/15/2010] [Indexed: 10/18/2022]
Abstract
We compared the efficacy of the novel sodium-hydrogen exchanger (NHE-1) inhibitor AVE4454B with cariporide for resuscitation from ventricular fibrillation (VF) assessing the effects on left ventricular myocardial distensibility during chest compression, myocardial function after the return of spontaneous circulation, and survival. Three groups of 10 rats each were subjected to 10 min of untreated VF and resuscitation attempted by providing chest compression for up to 8 min with the depth of compression adjusted to attain an aortic diastolic pressure between 26 and 28 mmHg (to secure a coronary perfusion pressure above 20 mmHg) followed by electrical shocks. Rats received AVE4454B (1 mg/kg), cariporide (1 mg/kg), or vehicle control immediately before chest compression. We observed that NHE-1 inhibition (NHEI) preserved left ventricular myocardial distensibility during chest compression evidenced by less depth of compression required to attain the target aortic diastolic pressure corresponding to (mean ± standard deviation) 14.1 ± 1.1 mm in the AVE4454B group (P < 0.001 versus control), 15.0 ± 1.4 mm in the cariporide group (P < 0.01 versus control), and 17.0 ± 1.2 mm in controls. When the depth of compression was related to the coronary perfusion pressure generated-an index of left ventricular distensibility-only the cariporide group attained statistical significance. Postresuscitation, both compounds ameliorated myocardial dysfunction evidenced by lesser reductions in mean aortic pressure and the maximal rate of left ventricular pressure increase as well as earlier normalization of left ventricular end-diastolic pressure increases. This effect was associated with improved survival corresponding to 55% in the AVE4454B group (not significant) and 70% in the cariporide group (P < 0.01 versus control by Gehan-Breslow analysis) at 240 min postresuscitation. An inverse correlation was found between plasma cytochrome c and indices of left ventricular function at 240 min postresuscitation suggesting that NHEI exerts beneficial effects in part by attenuating mitochondrial injury. We conclude that cariporide is more effective than AVE4454B for resuscitation from cardiac arrest given its more prominent effect on preserving left ventricular myocardial distensibility and promoting survival.
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Affiliation(s)
- Jeejabai Radhakrishnan
- Resuscitation Institute at Rosalind Franklin University of Medicine and Science and Medical Service, Section of Critical Care Medicine, Captain James A. Lovell Federal Health Care Center, North Chicago, Ill 60064, USA
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Law B, Tung CH. Proteolysis: A Biological Process Adapted in Drug Delivery, Therapy, and Imaging. Bioconjug Chem 2009; 20:1683-95. [DOI: 10.1021/bc800500a] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Benedict Law
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota 58105, and The Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, Texas 77030
| | - Ching-Hsuan Tung
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota 58105, and The Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, Texas 77030
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Ugawa S, Ishida Y, Ueda T, Inoue K, Nagao M, Shimada S. Nafamostat mesilate reversibly blocks acid-sensing ion channel currents. Biochem Biophys Res Commun 2007; 363:203-8. [PMID: 17826743 DOI: 10.1016/j.bbrc.2007.08.133] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 08/23/2007] [Indexed: 11/17/2022]
Abstract
We electrophysiologically investigated the effects of nafamostat mesilate (NM: 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfonate) and its two metabolites, 6-amidino-2-naphthol (AN) and p-guanidinobenzoic acid (PGBA), on three distinct types of human acid-sensing ion channels (ASICs). Acid-evoked inward currents at a holding potential of -60mV in ASIC1a- and ASIC2a-expressing oocytes were decreased by extracellular application of NM in a concentration-dependent manner with IC(50) (inhibition constant) values of approximately 13.5 and 70.6microM, respectively. The NM application also produced concentration-dependent inhibition of the initial-phase transient component of biphasic ASIC3 currents with an IC(50) value of approximately 2.5microM. Application of AN showed weak blocking effects on the ASIC1a, ASIC2a, and transient ASIC3 currents with IC(50) values of approximately 1.2, 1.3, and 0.14mM, respectively, whereas PGBA was insensitive to their currents.
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Affiliation(s)
- Shinya Ugawa
- Department of Neurobiology and Anatomy, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
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12
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De Vito P. The sodium/hydrogen exchanger: a possible mediator of immunity. Cell Immunol 2006; 240:69-85. [PMID: 16930575 DOI: 10.1016/j.cellimm.2006.07.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 06/30/2006] [Accepted: 07/05/2006] [Indexed: 10/24/2022]
Abstract
Immune cells such as macrophages and neutrophils provide the first line of defence of the immune system using phagocytosis, cytokine and chemokine synthesis and release, as well as Reactive Oxygen Species (ROS) generation. Many of these functions are positively coupled with cytoplasmic pH (pHi) and/or phagosomal pH (pHp) modification; an increase in pHi represents an important signal for cytokine and chemokine release, whereas a decrease in pHp can induce an efficient antigen presentation. However, the relationship between pHi and ROS generation is not well understood. In immune cells two main transport systems have been shown to regulate pHi: the Na+/H+ Exchanger (NHE) and the plasmalemmal V-type H+ ATPase. NHE is a family of proteins which exchange Na+ for H+ according to their concentration gradients in an electroneutral manner. The exchanger also plays a key role in several other cellular functions including proliferation, differentiation, apoptosis, migration, and cytoskeletal organization. Since not much is known on the relationship between NHE and immunity, this review outlines the contribution of NHE to different aspects of innate and adaptive immune responses such as phagosomal acidification, NADPH oxidase activation and ROS generation, cytokine and chemokine release as well as T cell apoptosis. The possibility that several pro-inflammatory diseases may be modulated by NHE activity is evaluated.
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Affiliation(s)
- Paolo De Vito
- Department of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy.
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