1
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Fenton CG, Ray MK, Meng W, Paulssen RH. Methylation-Regulated Long Non-Coding RNA Expression in Ulcerative Colitis. Int J Mol Sci 2023; 24:10500. [PMID: 37445676 DOI: 10.3390/ijms241310500] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/26/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Long non-coding RNAs (lncRNAs) have been shown to play a role in the pathogenesis of ulcerative colitis (UC). Although epigenetic processes such as DNA methylation and lncRNA expression are well studied in UC, the importance of the interplay between the two processes has not yet been fully explored. It is, therefore, believed that interactions between environmental factors and epigenetics contribute to disease development. Mucosal biopsies from 11 treatment-naïve UC patients and 13 normal controls were used in this study. From each individual sample, both whole-genome bisulfite sequencing data (WGBS) and lncRNA expression data were analyzed. Correlation analysis between lncRNA expression and upstream differentially methylated regions (DMRs) was used to identify lncRNAs that might be regulated by DMRs. Furthermore, proximal protein-coding genes associated with DMR-regulated lncRNAs were identified by correlating their expression. The study identified UC-associated lncRNAs such as MIR4435-2HG, ZFAS1, IL6-AS1, and Pvt1, which may be regulated by DMRs. Several genes that are involved in inflammatory immune responses were found downstream of DMR-regulated lncRNAs, including SERPINB1, CCL18, and SLC15A4. The interplay between lncRNA expression regulated by DNA methylation in UC might improve our understanding of UC pathogenesis.
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Affiliation(s)
- Christopher G Fenton
- Clinical Bioinformatics Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
- Genomic Support Centre Tromsø (GSCT), Department of Clinical Medicine, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Mithlesh Kumar Ray
- Clinical Bioinformatics Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Wei Meng
- Clinical Bioinformatics Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
| | - Ruth H Paulssen
- Clinical Bioinformatics Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
- Genomic Support Centre Tromsø (GSCT), Department of Clinical Medicine, UiT-The Arctic University of Norway, N-9037 Tromsø, Norway
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2
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Shi L, Jia L, Wang Y, Xiu M, Xie J. 4-Aminopyridine Protects Nigral Dopaminergic Neurons in the MPTP Mouse Model of Parkinson's Disease. Neurochem Res 2023; 48:1707-1715. [PMID: 36602724 DOI: 10.1007/s11064-022-03845-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 01/06/2023]
Abstract
Various pharmacological blockers targeting K+ channel have been identified to be related to the treatment of Parkinson's disease (PD). Previous studies showed that 4-Aminopyridine (4-AP), a wide-spectrum K+ channel blocker, was able to attenuate apomorphine-induced rotation in parkinsonism rats, indicating the possible beneficial effects in attenuation of PD motor symptoms. However, it is unclear whether 4-AP exhibits neuroprotective effects against the neurodegeneration of substantia nigra (SN)-striatum system in PD. In this study, the 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mouse model was employed to evaluate the neuroprotective effects of 4-AP. Results showed that 4-AP inhibited MPTP-induced dopaminergic neuronal loss in the SN as well as dopamine depletion in the striatum. Behavior indexes of open field test and rotarod test confirmed that 4-AP attenuated MPTP-induced motor deficits. We also showed that 4-AP treatment could significantly attenuate the MPTP-induced increase in malonaldehyde (MDA) levels and decrease in superoxide dismutase (SOD) levels. Additionally, MPTP significantly reduced the Bcl-2 expression and promoted the Caspase-3 activation; 4-AP protected dopaminergic neurons against MPTP-induced neurotoxicity by reversing these changes. These results indicate that 4-AP exerts a neuroprotective effect on dopaminergic neurons against MPTP by decreasing oxidative stress and apoptosis. This provides a promising therapeutic target for the treatment of PD.
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Affiliation(s)
- Limin Shi
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Lu Jia
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Yiyun Wang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Minxia Xiu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, School of Basic Medicine, Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Junxia Xie
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China.
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3
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Bustamante HA, Ehrich MF, Klein BG. Intracellular potassium depletion enhances apoptosis induced by staurosporine in cultured trigeminal satellite glial cells. Somatosens Mot Res 2021; 38:194-201. [PMID: 34187291 DOI: 10.1080/08990220.2021.1941843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PURPOSE Satellite glial cells (SGC) surrounding neurons in sensory ganglia can buffer extracellular potassium, regulating the excitability of injured neurons and possibly influencing a shift from acute to neuropathic pain. SGC apoptosis may be a key component in this process. This work evaluated induction or enhancement of apoptosis in cultured trigeminal SGC following changes in intracellular potassium [K]ic. MATERIALS AND METHODS We developed SGC primary cultures from rat trigeminal ganglia (TG). Purity of our cultures was confirmed using immunofluorescence and western blot analysis for the presence of the specific marker of SGC, glutamine synthetase (GS). SGC [K]ic was depleted using hypo-osmotic shock and 4 mM bumetanide plus 10 mM ouabain. [K]ic was measured using the K+ fluorescent indicator potassium benzofuran isophthalate (PBFI-AM). RESULTS SGC tested positive for GS and hypo-osmotic shock induced a significant decrease in [K]ic at every evaluated time. Cells were then incubated for 5 h with either 2 mM staurosporine (STS) or 20 ng/ml of TNF-α and evaluated for early apoptosis and late apoptosis/necrosis by flow cytometry using annexin V and propidium iodide. A significant increase in early apoptosis, from 16 to 38%, was detected in SGC with depleted [K]ic after incubation with STS. In contrast, TNF-α did not increase early apoptosis in normal or [K]ic depleted SGC. CONCLUSION Hypo-osmotic shock induced a decrease in intracellular potassium in cultured trigeminal SGC and this enhanced apoptosis induced by STS that is associated with the mitochondrial pathway. These results suggest that K+ dysregulation may underlie apoptosis in trigeminal SGC.
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Affiliation(s)
- Hedie A Bustamante
- Faculty of Veterinary Sciences, Veterinary Clinical Sciences Institute, Universidad Austral de Chile, Valdivia, Chile
| | - Marion F Ehrich
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Bradley G Klein
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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4
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Cosme D, Estevinho MM, Rieder F, Magro F. Potassium channels in intestinal epithelial cells and their pharmacological modulation: a systematic review. Am J Physiol Cell Physiol 2020; 320:C520-C546. [PMID: 33326312 DOI: 10.1152/ajpcell.00393.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Several potassium channels (KCs) have been described throughout the gastrointestinal tract. Notwithstanding, their contribution to both physiologic and pathophysiologic conditions, as inflammatory bowel disease (IBD), remains underexplored. Therefore, we aim to systematically review, for the first time, the evidence on the characteristics and modulation of KCs in intestinal epithelial cells (IECs). PubMed, Scopus, and Web of Science were searched to identify studies focusing on KCs and their modulation in IECs. The included studies were assessed using a reporting inclusiveness checklist. From the 745 identified records, 73 met the inclusion criteria; their reporting inclusiveness was moderate-high. Some studies described the physiological role of KCs, while others explored their importance in pathological settings. Globally, in IBD animal models, apical KCa1.1 channels, responsible for luminal secretion, were upregulated. In human colonocytes, basolateral KCa3.1 channels were downregulated. The pharmacological inhibition of K2P and Kv influenced intestinal barrier function, promoting inflammation. Evidence suggests a strong association between KCs expression and secretory mechanisms in human and animal IECs. Further research is warranted to explore the usefulness of KC pharmacological modulation as a therapeutic target.
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Affiliation(s)
- Dina Cosme
- Department of Biomedicine, Unit of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,MedInUP, Center for Drug Discovery and Innovative Medicines, Porto, Portugal
| | - Maria Manuela Estevinho
- Department of Biomedicine, Unit of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Gastroenterology, Centro Hospitalar Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
| | - Florian Rieder
- Department of Gastroenterology, Hepatology and Nutrition, Digestive Diseases, and Surgery Institute, Cleveland Clinic Foundation, Cleveland, Ohio.,Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Fernando Magro
- Department of Biomedicine, Unit of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,MedInUP, Center for Drug Discovery and Innovative Medicines, Porto, Portugal.,Department of Gastroenterology, Centro Hospitalar São João, Porto, Portugal
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5
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Bachmann M, Li W, Edwards MJ, Ahmad SA, Patel S, Szabo I, Gulbins E. Voltage-Gated Potassium Channels as Regulators of Cell Death. Front Cell Dev Biol 2020; 8:611853. [PMID: 33381507 PMCID: PMC7767978 DOI: 10.3389/fcell.2020.611853] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/23/2020] [Indexed: 12/11/2022] Open
Abstract
Ion channels allow the flux of specific ions across biological membranes, thereby determining ion homeostasis within the cells. Voltage-gated potassium-selective ion channels crucially contribute to the setting of the plasma membrane potential, to volume regulation and to the physiologically relevant modulation of intracellular potassium concentration. In turn, these factors affect cell cycle progression, proliferation and apoptosis. The present review summarizes our current knowledge about the involvement of various voltage-gated channels of the Kv family in the above processes and discusses the possibility of their pharmacological targeting in the context of cancer with special emphasis on Kv1.1, Kv1.3, Kv1.5, Kv2.1, Kv10.1, and Kv11.1.
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Affiliation(s)
- Magdalena Bachmann
- Department of Biology, University of Padova, Padua, Italy.,Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Weiwei Li
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Michael J Edwards
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Syed A Ahmad
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Sameer Patel
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padua, Italy.,Consiglio Nazionale delle Ricerche Institute of Neuroscience, Padua, Italy
| | - Erich Gulbins
- Department of Surgery, Medical School, University of Cincinnati, Cincinnati, OH, United States.,Department of Molecular Biology, University of Duisburg-Essen, Essen, Germany
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6
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Wang X, Zhao X. Prior lactose glycation of caseinate via the Maillard reaction affects in vitro activities of the pepsin-trypsin digest toward intestinal epithelial cells. J Dairy Sci 2017; 100:5125-5138. [DOI: 10.3168/jds.2016-12491] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/08/2017] [Indexed: 01/08/2023]
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7
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Galleria mellonella lysozyme induces apoptotic changes in Candida albicans cells. Microbiol Res 2016; 193:121-131. [PMID: 27825480 DOI: 10.1016/j.micres.2016.10.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 09/30/2016] [Accepted: 10/08/2016] [Indexed: 12/22/2022]
Abstract
The greater wax moth Galleria mellonella has been increasingly used as a model host to determine Candida albicans virulence and efficacy of antifungal treatment. The G. mellonella lysozyme, similarly to its human counterpart, is a member of the c-type family of lysozymes that exhibits antibacterial and antifungal activity. However, in contrast to the relatively well explained bactericidal action, the mechanism of fungistatic and/or fungicidal activity of lysozymes is still not clear. In the present study we provide the direct evidences that the G. mellonella lysozyme binds to the protoplasts as well as to the intact C. albicans cells and decreases the survival rate of both these forms in a time-dependent manner. No enzymatic activity of the lysozyme towards typical chitinase and β-glucanase substrates was detected, indicating that hydrolysis of main fungal cell wall components is not responsible for anti-Candida activity of the lysozyme. On the other hand, pre-treatment of cells with tetraethylammonium, a potassium channel blocker, prevented them from the lysozyme action, suggesting that lysozyme acts by induction of programmed cell death. In fact, the C. albicans cells treated with the lysozyme exhibited typical apoptotic features, i.e. loss of mitochondrial membrane potential, phosphatidylserine exposure in the outer leaflet of the cell membrane, as well as chromatin condensation and DNA fragmentation.
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8
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Pasantes-Morales H. Channels and Volume Changes in the Life and Death of the Cell. Mol Pharmacol 2016; 90:358-70. [PMID: 27358231 DOI: 10.1124/mol.116.104158] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/22/2016] [Indexed: 12/11/2022] Open
Abstract
Volume changes deviating from original cell volume represent a major challenge for cellular homeostasis. Cell volume may be altered either by variations in the external osmolarity or by disturbances in the transmembrane ion gradients that generate an osmotic imbalance. Cells respond to anisotonicity-induced volume changes by active regulatory mechanisms that modify the intracellular/extracellular concentrations of K(+), Cl(-), Na(+), and organic osmolytes in the direction necessary to reestablish the osmotic equilibrium. Corrective osmolyte fluxes permeate across channels that have a relevant role in cell volume regulation. Channels also participate as causal actors in necrotic swelling and apoptotic volume decrease. This is an overview of the types of channels involved in either corrective or pathologic changes in cell volume. The review also underlines the contribution of transient receptor potential (TRP) channels, notably TRPV4, in volume regulation after swelling and describes the role of other TRPs in volume changes linked to apoptosis and necrosis. Lastly we discuss findings showing that multimers derived from LRRC8A (leucine-rich repeat containing 8A) gene are structural components of the volume-regulated Cl(-) channel (VRAC), and we underline the intriguing possibility that different heteromer combinations comprise channels with different intrinsic properties that allow permeation of the heterogenous group of molecules acting as organic osmolytes.
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Affiliation(s)
- Herminia Pasantes-Morales
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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9
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Magalhães D, Cabral JM, Soares-da-Silva P, Magro F. Role of epithelial ion transports in inflammatory bowel disease. Am J Physiol Gastrointest Liver Physiol 2016; 310:G460-76. [PMID: 26744474 DOI: 10.1152/ajpgi.00369.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 01/02/2016] [Indexed: 02/06/2023]
Abstract
Inflammatory bowel disease (IBD) is a chronic inflammatory disorder with a complex pathogenesis. Diarrhea is a highly prevalent and often debilitating symptom of IBD patients that results, at least in part, from an intestinal hydroelectrolytic imbalance. Evidence suggests that reduced electrolyte absorption is more relevant than increased secretion to this disequilibrium. This systematic review analyses and integrates the current evidence on the roles of epithelial Na(+)-K(+)-ATPase (NKA), Na(+)/H(+) exchangers (NHEs), epithelial Na(+) channels (ENaC), and K(+) channels (KC) in IBD-associated diarrhea. NKA is the key driving force of the transepithelial ionic transport and its activity is decreased in IBD. In addition, the downregulation of apical NHE and ENaC and the upregulation of apical large-conductance KC all contribute to the IBD-associated diarrhea by lowering sodium absorption and/or increasing potassium secretion.
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Affiliation(s)
- Diogo Magalhães
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - José Miguel Cabral
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - Patrício Soares-da-Silva
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - Fernando Magro
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal; and MedInUP-Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
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10
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Dykstra NS, Hyde L, MacKenzie A, Mack DR. Lactobacillus plantarum 299v Prevents Caspase-Dependent Apoptosis In Vitro. Probiotics Antimicrob Proteins 2016; 3:21-6. [PMID: 26781496 DOI: 10.1007/s12602-011-9066-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Selective microbes used as probiotics can enhance epithelial cell protection. We have previously shown that a Lactobacillus plantarum strain 299v (Lp299v) has the ability to induce mucin genes. In the current study, we utilized a cytokine model of inflammation in cell culture to study the modulation of apoptosis by this probiotic. HT-29 cells were pre-incubated with the Lp299v or L. plantarum strain adh- (Lpadh-), a non-adherent derivative of Lp299v. Cells were challenged with a mixture of cytokines (TNF-α, IFN-γ, and IL-1a) to imitate conditions of inflammation. To assess for cell death, we evaluated TUNEL, multi-caspase, and caspase-3 and caspase-7 activity assays. There was a marked decrease in apoptosis as measured by TUNEL(+) cells in samples pre-treated with Lp299v (18.7 ± 4.1%, p < 0.01) and Lpadh- (16.6 ± 3.2%, p < 0.05) prior to cytokine exposure when compared to cells (43.6 ± 6.2%) exposed to the cytokine mixture. Lp299v pre-incubation with HT-29 cells reduced caspase(+) cells in the multi-caspase activity assay (3.6 ± 0.6%, p < 0.05) compared to cells exposed to cytokines (68.9 ± 5.1%) whereas Lpadh- did not (46.8 ± 17.5%, p > 0.05). Similarly, caspase-3, caspase-7 activity was also reduced by Lp299v. Selected probiotics may confer an exogenous protective effect at the mucosal-luminal interface for intestinal epithelial cells via alteration of caspase-dependent apoptotic pathways.
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Affiliation(s)
- Natalie S Dykstra
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada.,Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada
| | - Lucie Hyde
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada
| | - Alexander MacKenzie
- Department of Pediatrics, University of Ottawa, Ottawa, Canada.,Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada
| | - David R Mack
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Canada. .,Department of Pediatrics, University of Ottawa, Ottawa, Canada. .,Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada.
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11
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Smith F, Clark JE, Overman BL, Tozel CC, Huang JH, Rivier JEF, Blisklager AT, Moeser AJ. Early weaning stress impairs development of mucosal barrier function in the porcine intestine. Am J Physiol Gastrointest Liver Physiol 2010; 298:G352-63. [PMID: 19926814 PMCID: PMC2838512 DOI: 10.1152/ajpgi.00081.2009] [Citation(s) in RCA: 322] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Early life stress is a predisposing factor for the development of chronic intestinal disorders in adult life. Here, we show that stress associated with early weaning in pigs leads to impaired mucosal barrier function. Early weaning (15- to 21-day weaning age) resulted in sustained impairment in intestinal barrier function, as indicated by reductions in jejunal transepithelial electrical resistance and elevations in mucosal-to-serosal flux of paracellular probes [(3)H]mannitol and [(14)C]inulin measured at 5 and 9 wk of age, compared with that shown in late-weaned pigs (23- to 28-day weaning age). Elevated baseline short-circuit current was observed in jejunum from early-weaned pigs and was shown to be mediated via enhanced Cl(-) secretion. Jejunal barrier dysfunction in early-weaned pigs coincided with increased lamina propria immune cell density particularly mucosal mast cells. The mast cell stabilizer drug sodium cromoglycolate ameliorated barrier dysfunction and hypersecretion in early-weaned pigs, demonstrating an important role of mast cells. Furthermore, activation of mast cells ex vivo with c48/80 and corticotrophin-releasing factor (CRF) in pig jejunum mounted in Ussing chambers induced barrier dysfunction and elevations in short-circuit current that were inhibited with mast cell protease inhibitors. Experiments in which selective CRF receptor antagonists were administered to early-weaned pigs revealed that CRF receptor 1 (CRFr1) activation mediates barrier dysfunction and hypersecretion, whereas CRFr2 activation may be responsible for novel protective properties in the porcine intestine in response to early life stress.
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Affiliation(s)
- Feli Smith
- 1Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina;
| | - Jessica E. Clark
- 1Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina;
| | - Beth L. Overman
- 1Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina;
| | - Christena C. Tozel
- 1Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina;
| | - Jennifer H. Huang
- 1Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina;
| | - Jean E. F. Rivier
- 2Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, California; and
| | - Anthony T. Blisklager
- 3Department of Clinical Sciences, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina
| | - Adam J. Moeser
- 1Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina;
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12
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Emami CN, Petrosyan M, Giuliani S, Williams M, Hunter C, Prasadarao NV, Ford HR. Role of the host defense system and intestinal microbial flora in the pathogenesis of necrotizing enterocolitis. Surg Infect (Larchmt) 2010; 10:407-17. [PMID: 19943775 DOI: 10.1089/sur.2009.054] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Necrotizing enterocolitis (NEC) is a devastating disease that affects primarily the intestine of premature infants. Despite recent advances in neonatology, NEC remains a major cause of morbidity and mortality in neonates. Neonatal mucosal defenses and adherence of bacterial pathogens may play an important role in the pathogenesis of NEC. METHODS Review and synthesis of pertinent literature. RESULTS Putative factors that have been implicated in the pathogenesis of NEC include abnormal patterns of gut colonization by bacteria, immaturity of the host immune system and mucosal defense mechanisms, intestinal ischemia, formula feeding, and loss of intestinal epithelial barrier integrity. CONCLUSION Host defenses and intestinal microbial ecology are believed to play important roles in the pathogenesis of NEC. Commensal bacteria and probiotic therapy may be of therapeutic utility in the maintenance of the gut epithelial barrier.
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Affiliation(s)
- Claudia N Emami
- Department of Surgery, Childrens Hospital Los Angeles, Keck School of Medicine of University of Southern California, Los Angeles, California 90027, USA
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13
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Hu D, Liu J, Keblesh J, Xiong H. Involvement of the 4-aminopyridine-sensitive transient A-type K+ current in macrophage-induced neuronal injury. Eur J Neurosci 2010; 31:214-22. [PMID: 20074219 DOI: 10.1111/j.1460-9568.2009.07063.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Through their capacity to secrete, upon activation, a variety of bioactive molecules, brain macrophages (and resident microglia) play an important role in brain immune and inflammatory responses. To test our hypothesis that activated macrophages induce neuronal injury by enhancing neuronal outward K(+) current, we studied the effects of lipopolysaccharide (LPS)-stimulated human monocyte-derived macrophage (MDM) on neuronal transient A-type K(+) current (I(A)) and resultant neuronal injury in primary rat hippocampal neuronal cultures. Bath application of LPS-stimulated MDM-conditioned media (MCM+) enhanced neuronal I(A) in a concentration-dependent manner. Non-stimulated MCM (MCM-) failed to alter I(A). The enhancement of neuronal I(A) was recapitulated in neurons co-cultured with macrophages. The link of MCM(+)-induced enhancement of I(A) to MCM(+)-associated neuronal injury, as detected by propidium iodide and 4'',6-diamidino-2-phenylindol staining (DAPI) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, was demonstrated by experimental results showing that addition of I(A) blocker 4-aminopyridine to the cultures protected hippocampal neurons from MCM(+)-induced neuronal injury. Further investigation revealed that glutamate was involved in MCM(+)-induced enhancement of neuronal I(A). These results suggest that during brain inflammation macrophages (and microglia) might mediate neuronal injury via enhancement of neuronal I(A), and that neuronal K(v) channel might be a potential target for the development of therapeutic strategies for some neurodegenerative disorders by which immune and inflammatory responses are believed to be involved in the pathogenesis.
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Affiliation(s)
- Dehui Hu
- Center for Neurovirology and Neurodegenerative Disorders, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
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14
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Chan CM, Tsoi H, Chan WM, Zhai S, Wong CO, Yao X, Chan WY, Tsui SKW, Chan HYE. The ion channel activity of the SARS-coronavirus 3a protein is linked to its pro-apoptotic function. Int J Biochem Cell Biol 2009; 41:2232-9. [PMID: 19398035 PMCID: PMC7108357 DOI: 10.1016/j.biocel.2009.04.019] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 03/12/2009] [Accepted: 04/20/2009] [Indexed: 01/15/2023]
Abstract
The severe acute respiratory syndrome-coronavirus (SARS-CoV) caused an outbreak of atypical pneumonia in 2003. The SARS-CoV viral genome encodes several proteins which have no homology to proteins in any other coronaviruses, and a number of these proteins have been implicated in viral cytopathies. One such protein is 3a, which is also known as X1, ORF3 and U274. 3a expression is detected in both SARS-CoV infected cultured cells and patients. Among the different functions identified, 3a is a capable of inducing apoptosis. We previously showed that caspase pathways are involved in 3a-induced apoptosis. In this study, we attempted to find out protein domains on 3a that are essential for its pro-apoptotic function. Protein sequence analysis reveals that 3a possesses three major protein signatures, the cysteine-rich, Yxx phi and diacidic domains. We showed that 3a proteins carrying respective mutations in these protein domains exhibit reduced pro-apoptotic activities, indicating the importance of these domains on 3a's pro-apoptotic function. It was previously reported that 3a possesses potassium ion channel activity. We further demonstrated that the blockade of 3a's potassium channel activity abolished caspase-dependent apoptosis. This report provides the first evidence that ion channel activity of 3a is required for its pro-apoptotic function. As ion channel activity has been reported to regulate apoptosis in different pathologic conditions, finding ways to modulate the ion channel activity may offer a new direction toward the inhibition of apoptosis triggered by SARS-CoV.
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Affiliation(s)
- Chak-Ming Chan
- Laboratory of Drosophila Research, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
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15
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Rollo CD. Dopamine and Aging: Intersecting Facets. Neurochem Res 2008; 34:601-29. [DOI: 10.1007/s11064-008-9858-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 07/03/2008] [Indexed: 10/21/2022]
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16
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Heitzmann D, Warth R. Physiology and pathophysiology of potassium channels in gastrointestinal epithelia. Physiol Rev 2008; 88:1119-82. [PMID: 18626068 DOI: 10.1152/physrev.00020.2007] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Epithelial cells of the gastrointestinal tract are an important barrier between the "milieu interne" and the luminal content of the gut. They perform transport of nutrients, salts, and water, which is essential for the maintenance of body homeostasis. In these epithelia, a variety of K(+) channels are expressed, allowing adaptation to different needs. This review provides an overview of the current literature that has led to a better understanding of the multifaceted function of gastrointestinal K(+) channels, thereby shedding light on pathophysiological implications of impaired channel function. For instance, in gastric mucosa, K(+) channel function is a prerequisite for acid secretion of parietal cells. In epithelial cells of small intestine, K(+) channels provide the driving force for electrogenic transport processes across the plasma membrane, and they are involved in cell volume regulation. Fine tuning of salt and water transport and of K(+) homeostasis occurs in colonic epithelia cells, where K(+) channels are involved in secretory and reabsorptive processes. Furthermore, there is growing evidence for changes in epithelial K(+) channel expression during cell proliferation, differentiation, apoptosis, and, under pathological conditions, carcinogenesis. In the future, integrative approaches using functional and postgenomic/proteomic techniques will help us to gain comprehensive insights into the role of K(+) channels of the gastrointestinal tract.
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Affiliation(s)
- Dirk Heitzmann
- Institute of Physiology and Clinic and Policlinic for Internal Medicine II, Regensburg, Germany
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17
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Human lactoferrin induces apoptosis-like cell death in Candida albicans: critical role of K+-channel-mediated K+ efflux. Antimicrob Agents Chemother 2008; 52:4081-8. [PMID: 18710913 DOI: 10.1128/aac.01597-07] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Human lactoferrin (hLf) induced an apoptosis-like phenotype in Candida albicans cells, which includes phosphatidylserine externalization, nuclear chromatin condensation, DNA degradation, and increased reactive oxygen species (ROS) production. Intracellular ROS accumulation was seen to correlate with candidacidal activity in hLf-treated cells. Mitochondrial activity was involved as indicated by mitochondrial depolarization and increased hLf resistance of cells preincubated with sordarin or erythromycin, the latter of which inhibits protein synthesis in mitoribosomes. Interestingly, Cl(-)- and K(+)-channel blockers prevented the hLf antimicrobial activity, but only when cells were pretreated with the blocking agent (tetraethylammonium) prior to the hLf-induced K(+)-release period. These results indicate for the first time that K(+)-channel-mediated K(+) efflux is required for the progression of apoptosis-like process in yeast, suggesting that this essential apoptotic event of higher eukaryotes has been evolutionary conserved among species ranging from yeasts to humans.
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Redman PT, He K, Hartnett KA, Jefferson BS, Hu L, Rosenberg PA, Levitan ES, Aizenman E. Apoptotic surge of potassium currents is mediated by p38 phosphorylation of Kv2.1. Proc Natl Acad Sci U S A 2007; 104:3568-73. [PMID: 17360683 PMCID: PMC1805571 DOI: 10.1073/pnas.0610159104] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kv2.1, the primary delayed rectifying potassium channel in neurons, is extensively regulated by phosphorylation. Previous reports have described Kv2.1 phosphorylation events affecting channel gating and the impact of this process on cellular excitability. Kv2.1, however, also provides the critical exit route for potassium ions during neuronal apoptosis via p38 MAPK-dependent membrane insertion, resulting in a pronounced enhancement of K(+) currents. Here, electrophysiological and viability studies using Kv2.1 channel mutants identify a p38 phosphorylation site at Ser-800 (S800) that is required for Kv2.1 membrane insertion, K(+) current surge, and cell death. In addition, a phospho-specific antibody for S800 detects a p38-dependent increase in Kv2.1 phosphorylation in apoptotic neurons and reveals phosphorylation of S800 in immunopurified channels incubated with active p38. Consequently, phosphorylation of Kv2.1 residue S800 by p38 leads to trafficking and membrane insertion during apoptosis, and remarkably, the absence of S800 phosphorylation is sufficient to prevent completion of the cell death program.
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Affiliation(s)
| | - Kai He
- Departments of *Neurobiology and
| | | | | | - Linda Hu
- Department of Neurology and Program in Neuroscience, Children's Hospital and Harvard Medical School, Boston, MA 02115
| | - Paul A. Rosenberg
- Department of Neurology and Program in Neuroscience, Children's Hospital and Harvard Medical School, Boston, MA 02115
| | - Edwin S. Levitan
- Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261; and
| | - Elias Aizenman
- Departments of *Neurobiology and
- To whom correspondence should be addressed. E-mail:
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19
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Bortner CD, Cidlowski JA. Cell shrinkage and monovalent cation fluxes: role in apoptosis. Arch Biochem Biophys 2007; 462:176-88. [PMID: 17321483 PMCID: PMC1941616 DOI: 10.1016/j.abb.2007.01.020] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Revised: 01/18/2007] [Accepted: 01/23/2007] [Indexed: 12/25/2022]
Abstract
The loss of cell volume or cell shrinkage has been a morphological hallmark of the programmed cell death process known as apoptosis. This isotonic loss of cell volume has recently been term apoptotic volume decrease or AVD to distinguish it from inherent volume regulatory responses that occurs in cells under anisotonic conditions. Recent studies examining the intracellular signaling pathways that result in this unique cellular characteristic have determined that a fundamental movement of ions, particularly monovalent ions, underlie the AVD process and plays an important role on controlling the cell death process. An efflux of intracellular potassium was shown to be a critical aspect of the AVD process, as preventing this ion loss could protect cells from apoptosis. However, potassium plays a complex role as a loss of intracellular potassium has also been shown to be beneficial to the health of the cell. Additionally, the mechanisms that a cell employs to achieve this loss of intracellular potassium vary depending on the cell type and stimulus used to induce apoptosis, suggesting multiple ways exist to accomplish the same goal of AVD. Additionally, sodium and chloride have been shown to play a vital role during cell death in both the signaling and control of AVD in various apoptotic model systems. This review examines the relationship between this morphological change and intracellular monovalent ions during apoptosis.
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Affiliation(s)
- Carl D Bortner
- The Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Department of Health and Human Services, National Institutes of Health, Research Triangle Park, NC 27709, USA.
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20
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Redman PT, Jefferson BS, Ziegler CB, Mortensen OV, Torres GE, Levitan ES, Aizenman E. A vital role for voltage-dependent potassium channels in dopamine transporter-mediated 6-hydroxydopamine neurotoxicity. Neuroscience 2006; 143:1-6. [PMID: 17027171 PMCID: PMC2673085 DOI: 10.1016/j.neuroscience.2006.08.039] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 08/09/2006] [Accepted: 08/18/2006] [Indexed: 11/16/2022]
Abstract
6-Hydroxydopamine (6-OHDA), a neurotoxic substrate of the dopamine transporter (DAT), is widely used in Parkinson's disease models. However, the molecular mechanisms underlying 6-OHDA's selectivity for dopamine neurons and the injurious sequelae that it triggers are not well understood. We tested whether ectopic expression of DAT induces sensitivity to 6-OHDA in non-dopaminergic rat cortical neurons and evaluated the contribution of voltage-dependent potassium channel (Kv)-dependent apoptosis to the toxicity of this compound in rat cortical and midbrain dopamine neurons. Cortical neurons expressing DAT accumulated dopamine and were highly vulnerable to 6-OHDA. Pharmacological inhibition of DAT completely blocked this toxicity. We also observed a p38-dependent Kv current surge in DAT-expressing cortical neurons exposed to 6-OHDA, and p38 antagonists and Kv channel blockers were neuroprotective in this model. Thus, DAT-mediated uptake of 6-OHDA recruited the oxidant-induced Kv channel dependent cell death pathway present in cortical neurons. Finally, we report that 6-OHDA also increased Kv currents in cultured midbrain dopamine neurons and this toxicity was blocked with Kv channel antagonists. We conclude that native DAT expression accounts for the dopamine neuron specific toxicity of 6-OHDA. Following uptake, 6-OHDA triggers the oxidant-associated Kv channel-dependent cell death pathway that is conserved in non-dopaminergic cortical neurons and midbrain dopamine neurons.
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Affiliation(s)
- Patrick T. Redman
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Bahiyyah S. Jefferson
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Chandra B. Ziegler
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Ole V. Mortensen
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Gonzalo E. Torres
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Edwin S. Levitan
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Elias Aizenman
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Corresponding author: Dr. Elias Aizenman, Department of Neurobiology, University of Pittsburgh School of Medicine, E1456 BST, Pittsburgh, PA 15261 U.S.A. Tel: (412) 648-9434; fax: (412) 648-1441;
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Abstract
A proper rate of programmed cell death or apoptosis is required to maintain normal tissue homeostasis. In disease states such as cancer and some forms of hypertension, apoptosis is blocked, resulting in hyperplasia. In neurodegenerative diseases, uncontrolled apoptosis leads to loss of brain tissue. The flow of ions in and out of the cell and its intracellular organelles is becoming increasingly linked to the generation of many of these diseased states. This review focuses on the transport of K(+) across the cell membrane and that of the mitochondria via integral K(+)-permeable channels. We describe the different types of K(+) channels that have been identified, and investigate the roles they play in controlling the different phases of apoptosis: early cell shrinkage, cytochrome c release, caspase activation, and DNA fragmentation. Attention is also given to K(+) channels on the inner mitochondrial membrane, whose activity may underlie anti- or pro-apoptotic mechanisms in neurons and cardiomyocytes.
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Affiliation(s)
- E D Burg
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC 0725, La Jolla, 92093-0725, USA
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