51
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Yang X, Wang G, Cao T, Zhang L, Ma Y, Jiang S, Teng X, Sun X. Large-conductance calcium-activated potassium channels mediate lipopolysaccharide-induced activation of murine microglia. J Biol Chem 2019; 294:12921-12932. [PMID: 31296663 DOI: 10.1074/jbc.ra118.006425] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 07/02/2019] [Indexed: 12/28/2022] Open
Abstract
Large-conductance calcium-activated potassium (BK) channels are ubiquitously expressed in most cell types where they regulate many cellular, organ, and organismal functions. Although BK currents have been recorded specifically in activated murine and human microglia, it is not yet clear whether and how the function of this channel is related to microglia activation. Here, using patch-clamping, Griess reaction, ELISA, immunocytochemistry, and immunoblotting approaches, we show that specific inhibition of the BK channel with paxilline (10 μm) or siRNA-mediated knockdown of its expression significantly suppresses lipopolysaccharide (LPS)-induced (100 ng/ml) BV-2 and primary mouse microglial cell activation. We found that membrane BK current is activated by LPS at a very early stage through Toll-like receptor 4 (TLR4), leading to nuclear translocation of NF-κB and to production of inflammatory cytokines. Furthermore, we noted that BK channels are also expressed intracellularly, and their nuclear expression significantly increases in late stages of LPS-mediated microglia activation, possibly contributing to production of nitric oxide, tumor necrosis factor-α, and interleukin-6. Of note, a specific TLR4 inhibitor suppressed BK channel expression, whereas an NF-κB inhibitor did not. Taken together, our findings indicate that BK channels participate in both the early and the late stages of LPS-stimulated murine microglia activation involving both membrane-associated and nuclear BK channels.
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Affiliation(s)
- Xiaoying Yang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Guiqin Wang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Ting Cao
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Li Zhang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Yunzhi Ma
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Shuhui Jiang
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Xinchen Teng
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China
| | - Xiaohui Sun
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Collaborative Innovation Center for Brain Science, College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China.
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52
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Biology and Bias in Cell Type-Specific RNAseq of Nucleus Accumbens Medium Spiny Neurons. Sci Rep 2019; 9:8350. [PMID: 31171808 PMCID: PMC6554355 DOI: 10.1038/s41598-019-44798-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 05/24/2019] [Indexed: 12/25/2022] Open
Abstract
Subcellular RNAseq promises to dissect transcriptional dynamics but is not well characterized. Furthermore, FACS may introduce bias but has not been benchmarked genome-wide. Finally, D1 and D2 dopamine receptor-expressing medium spiny neurons (MSNs) of the nucleus accumbens (NAc) are fundamental to neuropsychiatric traits but have only a short list of canonical surface markers. We address these gaps by systematically comparing nuclear-FACS, whole cell-FACS, and RiboTag affinity purification from D1- and D2-MSNs. Using differential expression, variance partitioning, and co-expression, we identify the following trade-offs for each method. RiboTag-seq best distinguishes D1- and D2-MSNs but has the lowest transcriptome coverage. Nuclear-FACS-seq generates the most differentially expressed genes and overlaps significantly with neuropsychiatric genetic risk loci, but un-annotated genes hamper interpretation. Whole cell-FACS is more similar to nuclear-FACS than RiboTag, but captures aspects of both. Using pan-method approaches, we discover that transcriptional regulation is predominant in D1-MSNs, while D2-MSNs tend towards cytosolic regulation. We are also the first to find evidence for moderate sexual dimorphism in these cell types at baseline. As these results are from 49 mice (nmale = 39, nfemale = 10), they represent generalizable ground-truths. Together, these results guide RNAseq methods selection, define MSN transcriptomes, highlight neuronal sex differences, and provide a baseline for D1- and D2-MSNs.
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53
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Balbaa AO, El-Fattah AA, Awad NM, Abdellatif A. Effects of nanoscale electric fields on the histology of liver cell dysplasia. Nanomedicine (Lond) 2019; 14:515-528. [PMID: 30807249 DOI: 10.2217/nnm-2018-0260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cells electrical fields have a significant role in cell function. AIM The current study examined the effects of nanoscale electric fields generated by magneto-electric nanoparticles (MENs) on precancerous liver tissue. METHODS & RESULTS A total of 30 nm MENs synthesized by sol-gel method were tested in vitro on HepG2 cells and in vivo on liver cell dysplasia in mice, which were exposed to 50 Hz 2 mT for 2 weeks, +/- MENs. MENs with alternating field (AF) reversed liver cells dysplastic features. In vitro cytotoxicity assay showed high lethal dose (LD 50) of 1.4 mg/ml. We also report on the expression of alpha-fetoprotein and cytochrome C. CONCLUSION MEN-generated nanoscale electric fields have significant biological effects on precancerous liver cells.
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Affiliation(s)
- Aya O Balbaa
- Medical Research Institute, Faculty of Medicine, Ain Shams University, Cairo, Egypt.,Biology Department, School of Sciences & Engineering, American University in Cairo, New Cairo 11835, Egypt
| | - Ahmed Abd El-Fattah
- Department of Materials Science, Institute of Graduate Studies & Research, Alexandria University, Alexandria, Egypt.,Department of Chemistry, College of Science, University of Bahrain
| | - Nahla M Awad
- Early Cancer Detection Unit. Ain Shams University Hospitals, Cairo, Egypt
| | - Ahmed Abdellatif
- Biology Department, School of Sciences & Engineering, American University in Cairo, New Cairo 11835, Egypt
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54
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Abstract
Ca2+- and voltage-gated K+ channels of large conductance (BK channels) are expressed in a diverse variety of both excitable and inexcitable cells, with functional properties presumably uniquely calibrated for the cells in which they are found. Although some diversity in BK channel function, localization, and regulation apparently arises from cell-specific alternative splice variants of the single pore-forming α subunit ( KCa1.1, Kcnma1, Slo1) gene, two families of regulatory subunits, β and γ, define BK channels that span a diverse range of functional properties. We are just beginning to unravel the cell-specific, physiological roles served by BK channels of different subunit composition.
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Affiliation(s)
- Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA;
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55
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Capera J, Serrano-Novillo C, Navarro-Pérez M, Cassinelli S, Felipe A. The Potassium Channel Odyssey: Mechanisms of Traffic and Membrane Arrangement. Int J Mol Sci 2019; 20:ijms20030734. [PMID: 30744118 PMCID: PMC6386995 DOI: 10.3390/ijms20030734] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/29/2022] Open
Abstract
Ion channels are transmembrane proteins that conduct specific ions across biological membranes. Ion channels are present at the onset of many cellular processes, and their malfunction triggers severe pathologies. Potassium channels (KChs) share a highly conserved signature that is necessary to conduct K⁺ through the pore region. To be functional, KChs require an exquisite regulation of their subcellular location and abundance. A wide repertoire of signatures facilitates the proper targeting of the channel, fine-tuning the balance that determines traffic and location. These signature motifs can be part of the secondary or tertiary structure of the protein and are spread throughout the entire sequence. Furthermore, the association of the pore-forming subunits with different ancillary proteins forms functional complexes. These partners can modulate traffic and activity by adding their own signatures as well as by exposing or masking the existing ones. Post-translational modifications (PTMs) add a further dimension to traffic regulation. Therefore, the fate of a KCh is not fully dependent on a gene sequence but on the balance of many other factors regulating traffic. In this review, we assemble recent evidence contributing to our understanding of the spatial expression of KChs in mammalian cells. We compile specific signatures, PTMs, and associations that govern the destination of a functional channel.
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Affiliation(s)
- Jesusa Capera
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Clara Serrano-Novillo
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - María Navarro-Pérez
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
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56
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Goswami SK, Ponnalagu D, Hussain AT, Shah K, Karekar P, Gururaja Rao S, Meredith AL, Khan M, Singh H. Expression and Activation of BK Ca Channels in Mice Protects Against Ischemia-Reperfusion Injury of Isolated Hearts by Modulating Mitochondrial Function. Front Cardiovasc Med 2019; 5:194. [PMID: 30746365 PMCID: PMC6360169 DOI: 10.3389/fcvm.2018.00194] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 12/18/2018] [Indexed: 12/14/2022] Open
Abstract
Aims: Activation and expression of large conductance calcium and voltage-activated potassium channel (BKCa) by pharmacological agents have been implicated in cardioprotection from ischemia-reperfusion (IR) injury possibly by regulating mitochondrial function. Given the non-specific effects of pharmacological agents, it is not clear whether activation of BKCa is critical to cardioprotection. In this study, we aimed to decipher the mechanistic role of BKCa in cardioprotection from IR injury by genetically activating BKCa channels. Methods and Results: Hearts from adult (3 months old) wild-type mice (C57/BL6) and mice expressing genetically activated BKCa (Tg-BKCa R207Q, referred as Tg-BKCa) along with wild-type BKCa were subjected to 20 min of ischemia and 30 min of reperfusion with or without ischemic preconditioning (IPC, 2 times for 2.5 min interval each). Left ventricular developed pressure (LVDP) was recorded using Millar's Mikrotip® catheter connected to ADInstrument data acquisition system. Myocardial infarction was quantified by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Our results demonstrated that Tg-BKCa mice are protected from IR injury, and BKCa also contributes to IPC-mediated cardioprotection. Cardiac function parameters were also measured by echocardiography and no differences were observed in left ventricular ejection fraction, fractional shortening and aortic velocities. Amplex Red® was used to assess reactive oxygen species (ROS) production in isolated mitochondria by spectrofluorometry. We found that genetic activation of BKCa reduces ROS after IR stress. Adult cardiomyocytes and mitochondria from Tg-BKCa mice were isolated and labeled with Anti-BKCa antibodies. Images acquired via confocal microscopy revealed localization of cardiac BKCa in the mitochondria. Conclusions: Activation of BKCa is essential for recovery of cardiac function after IR injury and is likely a factor in IPC mediated cardioprotection. Genetic activation of BKCa reduces ROS produced by complex I and complex II/III in Tg-BKCa mice after IR, and IPC further decreases it. These results implicate BKCa-mediated cardioprotection, in part, by reducing mitochondrial ROS production. Localization of Tg-BKCa in adult cardiomyocytes of transgenic mice was similar to BKCa in wild-type mice.
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Affiliation(s)
- Sumanta Kumar Goswami
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Devasena Ponnalagu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Ahmed T Hussain
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Kajol Shah
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Priyanka Karekar
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Shubha Gururaja Rao
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Andrea L Meredith
- Department of Physiology, University of Maryland, Baltimore, MD, United States
| | - Mahmood Khan
- Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States.,Department of Emergency Medicine, Wexner Medical Center, Ohio State University, Columbus, OH, United States
| | - Harpreet Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, OH, United States
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57
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Leanza L, Checchetto V, Biasutto L, Rossa A, Costa R, Bachmann M, Zoratti M, Szabo I. Pharmacological modulation of mitochondrial ion channels. Br J Pharmacol 2019; 176:4258-4283. [PMID: 30440086 DOI: 10.1111/bph.14544] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 10/15/2018] [Accepted: 10/22/2018] [Indexed: 12/17/2022] Open
Abstract
The field of mitochondrial ion channels has undergone a rapid development during the last three decades, due to the molecular identification of some of the channels residing in the outer and inner membranes. Relevant information about the function of these channels in physiological and pathological settings was gained thanks to genetic models for a few, mitochondria-specific channels. However, many ion channels have multiple localizations within the cell, hampering a clear-cut determination of their function by pharmacological means. The present review summarizes our current knowledge about the ins and outs of mitochondrial ion channels, with special focus on the channels that have received much attention in recent years, namely, the voltage-dependent anion channels, the permeability transition pore (also called mitochondrial megachannel), the mitochondrial calcium uniporter and some of the inner membrane-located potassium channels. In addition, possible strategies to overcome the difficulties of specifically targeting mitochondrial channels versus their counterparts active in other membranes are discussed, as well as the possibilities of modulating channel function by small peptides that compete for binding with protein interacting partners. Altogether, these promising tools along with large-scale chemical screenings set up to identify new, specific channel modulators will hopefully allow us to pinpoint the actual function of most mitochondrial ion channels in the near future and to pharmacologically affect important pathologies in which they are involved, such as neurodegeneration, ischaemic damage and cancer. LINKED ARTICLES: This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc.
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Affiliation(s)
- Luigi Leanza
- Department of Biology, University of Padova, Padova, Italy
| | | | - Lucia Biasutto
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Andrea Rossa
- Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Roberto Costa
- Department of Biology, University of Padova, Padova, Italy
| | | | - Mario Zoratti
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Ildiko Szabo
- Department of Biology, University of Padova, Padova, Italy.,CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Padova, Italy
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58
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Zhou Y, Xia XM, Lingle CJ. BK channel inhibition by strong extracellular acidification. eLife 2018; 7:38060. [PMID: 29963986 PMCID: PMC6054526 DOI: 10.7554/elife.38060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/01/2018] [Indexed: 12/24/2022] Open
Abstract
Mammalian BK-type voltage- and Ca2+-dependent K+ channels are found in a wide range of cells and intracellular organelles. Among different loci, the composition of the extracellular microenvironment, including pH, may differ substantially. For example, it has been reported that BK channels are expressed in lysosomes with their extracellular side facing the strongly acidified lysosomal lumen (pH ~4.5). Here we show that BK activation is strongly and reversibly inhibited by extracellular H+, with its conductance-voltage relationship shifted by more than +100 mV at pHO 4. Our results reveal that this inhibition is mainly caused by H+ inhibition of BK voltage-sensor (VSD) activation through three acidic residues on the extracellular side of BK VSD. Given that these key residues (D133, D147, D153) are highly conserved among members in the voltage-dependent cation channel superfamily, the mechanism underlying BK inhibition by extracellular acidification might also be applicable to other members in the family.
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Affiliation(s)
- Yu Zhou
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Xiao-Ming Xia
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States
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59
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Tseng HHL, Vong CT, Kwan YW, Lee SMY, Hoi MPM. Lysosomal Ca 2+ Signaling Regulates High Glucose-Mediated Interleukin-1β Secretion via Transcription Factor EB in Human Monocytic Cells. Front Immunol 2017; 8:1161. [PMID: 28970837 PMCID: PMC5609581 DOI: 10.3389/fimmu.2017.01161] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 09/01/2017] [Indexed: 01/16/2023] Open
Abstract
Aberrant activation of the innate immune system, including NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome-dependent interleukin-1β (IL-1β) secretion, has been implicated in the pathogenesis of type 2 diabetes mellitus (T2DM) and its complication. Our previous study demonstrated that hyperglycemia, a hallmark characteristic of T2DM, induced NLRP3 inflammasome-dependent caspase-1 activation and IL-1β maturation in human monocytic cells. In this study, we examined the underlying mechanisms of secreting IL-1β during hyperglycemia, with a focus on the alteration of Ca2+ homeostasis and lysosomal exocytosis. We found that high glucose (HG; 30 mM glucose for 48 h) altered Ca2+ homeostasis by reducing lysosomal Ca2+ concentration that appeared to be resulted from Ca2+ moving out of lysosomes into cytosol in human monocytic cell lines, U937 and THP-1 cells. Moreover, HG-induced lysosomal Ca2+-dependent mature IL-1β release was strongly correlated with the activation and upregulation of two lysosomal marker proteins, cathepsin D and lysosomal-associated membrane protein-1 (LAMP-1). This involved calcineurin/transcription factor EB (TFEB) pathway and its target genes, cathepsin B, cathepsin D, and LAMP-1, to mediate lysosomal exocytosis. Therefore in this study, we revealed a novel mechanism of HG-induced lysosomal exocytosis which was regulated by lysosomal Ca2+ signals through calcineurin/TFEB pathway, thus contributing to IL-1β secretion in human monocytic cells.
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Affiliation(s)
- Hisa Hui Ling Tseng
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau
| | - Chi Teng Vong
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau
| | - Yiu Wa Kwan
- Faculty of Medicine, School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Simon Ming-Yuen Lee
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau
| | - Maggie Pui Man Hoi
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Taipa, Macau
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60
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Wang W, Zhang X, Gao Q, Lawas M, Yu L, Cheng X, Gu M, Sahoo N, Li X, Li P, Ireland S, Meredith A, Xu H. A voltage-dependent K + channel in the lysosome is required for refilling lysosomal Ca 2+ stores. J Cell Biol 2017; 216:1715-1730. [PMID: 28468834 PMCID: PMC5461029 DOI: 10.1083/jcb.201612123] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/05/2017] [Accepted: 04/10/2017] [Indexed: 01/04/2023] Open
Abstract
Ion-dependent channels and transporters have been identified in lysosomes, including the V-ATPase H+ pump and transient receptor potential mucolipin channels (TRPMLs), the principle Ca2+ release channels in the lysosome, but much less is understood about the roles of Na+ and K+ in lysosomal physiology. Wang et al. describe a voltage-sensitive, Ca2+-activated K+ current in the lysosome (LysoKVCa) and show that LysoKVCa regulates lysosomal membrane potential and refilling of lysosomal Ca2+ stores. The resting membrane potential (Δψ) of the cell is negative on the cytosolic side and determined primarily by the plasma membrane’s selective permeability to K+. We show that lysosomal Δψ is set by lysosomal membrane permeabilities to Na+ and H+, but not K+, and is positive on the cytosolic side. An increase in juxta-lysosomal Ca2+ rapidly reversed lysosomal Δψ by activating a large voltage-dependent and K+-selective conductance (LysoKVCa). LysoKVCa is encoded molecularly by SLO1 proteins known for forming plasma membrane BK channels. Opening of single LysoKVCa channels is sufficient to cause the rapid, striking changes in lysosomal Δψ. Lysosomal Ca2+ stores may be refilled from endoplasmic reticulum (ER) Ca2+ via ER–lysosome membrane contact sites. We propose that LysoKVCa serves as the perilysosomal Ca2+ effector to prime lysosomes for the refilling process. Consistently, genetic ablation or pharmacological inhibition of LysoKVCa, or abolition of its Ca2+ sensitivity, blocks refilling and maintenance of lysosomal Ca2+ stores, resulting in lysosomal cholesterol accumulation and a lysosome storage phenotype.
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Affiliation(s)
- Wuyang Wang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Xiaoli Zhang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Qiong Gao
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Maria Lawas
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Lu Yu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Xiping Cheng
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Mingxue Gu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Nirakar Sahoo
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Xinran Li
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Ping Li
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109.,Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, China
| | - Stephen Ireland
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Andrea Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
| | - Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
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61
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Li Y, You QL, Zhang SR, Huang WY, Zou WJ, Jie W, Li SJ, Liu JH, Lv CY, Cong J, Hu YY, Gao TM, Li JM. Satb2 Ablation Impairs Hippocampus-Based Long-Term Spatial Memory and Short-Term Working Memory and Immediate Early Genes (IEGs)-Mediated Hippocampal Synaptic Plasticity. Mol Neurobiol 2017:10.1007/s12035-017-0531-5. [PMID: 28421537 DOI: 10.1007/s12035-017-0531-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/06/2017] [Indexed: 10/19/2022]
Abstract
Special AT-rich sequence-binding protein 2 (Satb2) is a protein binding to the matrix attachment regions of DNA and important for gene regulation. Patients with SATB2 mutation usually suffer moderate to severe mental retardation. However, the mechanisms for the defects of intellectual activities in patients with SATB2 mutation are largely unclear. Here we established the heterozygous Satb2 mutant mice and Satb2 conditional knockout mice to mimic the patients with SATB2 mutation and figured out the role of Satb2 in mental activities. We found that the spatial memory and working memory were significantly damaged in the heterozygous Satb2 mutant mice, early postnatal Satb2-deficient mice (CaMKIIα-Cre+Satb2fl/fl mice), and adult Satb2 ablation mice (Satb2fl/fl mice injected with CaMKIIα-Cre virus). Functionally, late phase long-term potentiation (L-LTP) in these Satb2 mutant mice was greatly impaired. Morphologically, in CA1 neurons of CaMKIIα-Cre+Satb2fl/fl mice, we found decreased spine density of the basal dendrites and less branches of apical dendrites that extended into lacunar molecular layer. Mechanistically, expression levels of immediate early genes (IEGs) including Fos, FosB, and Egr1 were significantly decreased after Satb2 deletion. And, Satb2 could regulate expression of FosB by binding to the promoter of FosB directly. In general, our study uncovers that Satb2 plays an important role in spatial memory and working memory by regulating IEGs-mediated hippocampal synaptic plasticity.
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Affiliation(s)
- Ying Li
- Department of Pathology, Sun Yat-Sen Memorial Hospital, Guangzhou, 510120, People's Republic of China
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, People's Republic of China
- Department of Pathology, Chancheng Central Hospital, Foshan, 528031, People's Republic of China
| | - Qiang-Long You
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Sheng-Rong Zhang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Wei-Yuan Huang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Wen-Jun Zou
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Wei Jie
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Shu-Ji Li
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Ji-Hong Liu
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Chuang-Ye Lv
- College of Clinical Medical, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Jin Cong
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Yu-Ying Hu
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, People's Republic of China
| | - Tian-Ming Gao
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, People's Republic of China.
| | - Jian-Ming Li
- Department of Pathology, Sun Yat-Sen Memorial Hospital, Guangzhou, 510120, People's Republic of China.
- Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, People's Republic of China.
- Department of Pathology, Soochow University Medical School, Suzhou, 215123, People's Republic of China.
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Zhang G, Geng Y, Jin Y, Shi J, McFarland K, Magleby KL, Salkoff L, Cui J. Deletion of cytosolic gating ring decreases gate and voltage sensor coupling in BK channels. J Gen Physiol 2017; 149:373-387. [PMID: 28196879 PMCID: PMC5339509 DOI: 10.1085/jgp.201611646] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Revised: 10/28/2016] [Accepted: 12/28/2016] [Indexed: 12/26/2022] Open
Abstract
Both cellular depolarization and intracellular Ca2+ can gate open large conductance Ca2+-activated K+ channels. Zhang et al. show that the intracellular gating ring, which forms the Ca2+-sensing machinery of the channel, is also required for activated voltage sensors to effectively gate open the pore. Large conductance Ca2+-activated K+ channels (BK channels) gate open in response to both membrane voltage and intracellular Ca2+. The channel is formed by a central pore-gate domain (PGD), which spans the membrane, plus transmembrane voltage sensors and a cytoplasmic gating ring that acts as a Ca2+ sensor. How these voltage and Ca2+ sensors influence the common activation gate, and interact with each other, is unclear. A previous study showed that a BK channel core lacking the entire cytoplasmic gating ring (Core-MT) was devoid of Ca2+ activation but retained voltage sensitivity (Budelli et al. 2013. Proc. Natl. Acad. Sci. USA. http://dx.doi.org/10.1073/pnas.1313433110). In this study, we measure voltage sensor activation and pore opening in this Core-MT channel over a wide range of voltages. We record gating currents and find that voltage sensor activation in this truncated channel is similar to WT but that the coupling between voltage sensor activation and gating of the pore is reduced. These results suggest that the gating ring, in addition to being the Ca2+ sensor, enhances the effective coupling between voltage sensors and the PGD. We also find that removal of the gating ring alters modulation of the channels by the BK channel’s β1 and β2 subunits.
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Affiliation(s)
- Guohui Zhang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130
| | - Yanyan Geng
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Yakang Jin
- Department of Pharmacology, Soochow University College of Pharmaceutical Sciences, Suzhou 215123, China
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130
| | - Kelli McFarland
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130
| | - Karl L Magleby
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Lawrence Salkoff
- Department of Anatomy and Neurobiology (Department of Neuroscience), Washington University School of Medicine in St. Louis, St. Louis, MO 63110.,Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO 63110
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130 .,Department of Pharmacology, Soochow University College of Pharmaceutical Sciences, Suzhou 215123, China
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63
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Latorre R, Castillo K, Carrasquel-Ursulaez W, Sepulveda RV, Gonzalez-Nilo F, Gonzalez C, Alvarez O. Molecular Determinants of BK Channel Functional Diversity and Functioning. Physiol Rev 2017; 97:39-87. [DOI: 10.1152/physrev.00001.2016] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Large-conductance Ca2+- and voltage-activated K+ (BK) channels play many physiological roles ranging from the maintenance of smooth muscle tone to hearing and neurosecretion. BK channels are tetramers in which the pore-forming α subunit is coded by a single gene ( Slowpoke, KCNMA1). In this review, we first highlight the physiological importance of this ubiquitous channel, emphasizing the role that BK channels play in different channelopathies. We next discuss the modular nature of BK channel-forming protein, in which the different modules (the voltage sensor and the Ca2+ binding sites) communicate with the pore gates allosterically. In this regard, we review in detail the allosteric models proposed to explain channel activation and how the models are related to channel structure. Considering their extremely large conductance and unique selectivity to K+, we also offer an account of how these two apparently paradoxical characteristics can be understood consistently in unison, and what we have learned about the conduction system and the activation gates using ions, blockers, and toxins. Attention is paid here to the molecular nature of the voltage sensor and the Ca2+ binding sites that are located in a gating ring of known crystal structure and constituted by four COOH termini. Despite the fact that BK channels are coded by a single gene, diversity is obtained by means of alternative splicing and modulatory β and γ subunits. We finish this review by describing how the association of the α subunit with β or with γ subunits can change the BK channel phenotype and pharmacology.
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Affiliation(s)
- Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Willy Carrasquel-Ursulaez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Romina V. Sepulveda
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Fernando Gonzalez-Nilo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Osvaldo Alvarez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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64
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Kuntamallappanavar G, Bisen S, Bukiya AN, Dopico AM. Differential distribution and functional impact of BK channel beta1 subunits across mesenteric, coronary, and different cerebral arteries of the rat. Pflugers Arch 2016; 469:263-277. [PMID: 28012000 DOI: 10.1007/s00424-016-1929-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/06/2016] [Accepted: 12/12/2016] [Indexed: 12/12/2022]
Abstract
Large conductance, Ca2+i- and voltage-gated K+ (BK) channels regulate myogenic tone and, thus, arterial diameter. In smooth muscle (SM), BK channels include channel-forming α and auxiliary β1 subunits. BK β1 increases the channel's Ca2+ sensitivity, allowing BK channels to negatively feedback on depolarization-induced Ca2+ entry, oppose SM contraction and favor vasodilation. Thus, endothelial-independent vasodilation can be evoked though targeting of SM BK β1 by endogenous ligands, including lithocholate (LCA). Here, we investigated the expression of BK β1 across arteries of the cerebral and peripheral circulations, and the contribution of such expression to channel function and BK β1-mediated vasodilation. Data demonstrate that endothelium-independent, BK β1-mediated vasodilation by LCA is larger in coronary (CA) and basilar (BA) arteries than in anterior cerebral (ACA), middle cerebral (MCA), posterior cerebral (PCA), and mesenteric (MA) arteries, all arterial segments having a similar diameter. Thus, differential dilation occurs in extracranial arteries which are subjected to similar vascular pressure (CA vs. MA) and in arteries that irrigate different brain regions (BA vs. ACA, MCA, and PCA). SM BK channels from BA and CA displayed increased basal activity and LCA responses, indicating increased BK β1 functional presence. Indeed, in the absence of detectable changes in BK α, BA and CA myocytes showed an increased location of BK β1 in the plasmalemma/subplasmalemma. Moreover, these myocytes distinctly showed increased BK β1 messenger RNA (mRNA) levels. Supporting a major role of enhanced BK β1 transcripts in artery dilation, LCA-induced dilation of MCA transfected with BK β1 complementary DNA (cDNA) was as high as LCA-induced dilation of untransfected BA or CA.
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Affiliation(s)
- Guruprasad Kuntamallappanavar
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA
| | - Shivantika Bisen
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA
| | - Anna N Bukiya
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA
| | - Alex M Dopico
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA.
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65
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Calycosin and Formononetin Induce Endothelium-Dependent Vasodilation by the Activation of Large-Conductance Ca 2+-Activated K + Channels (BK Ca). EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 2016:5272531. [PMID: 27994632 PMCID: PMC5141325 DOI: 10.1155/2016/5272531] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/26/2016] [Accepted: 10/19/2016] [Indexed: 12/13/2022]
Abstract
Calycosin and formononetin are two structurally similar isoflavonoids that have been shown to induce vasodilation in aorta and conduit arteries, but study of their actions on endothelial functions is lacking. Here, we demonstrated that both isoflavonoids relaxed rat mesenteric resistance arteries in a concentration-dependent manner, which was reduced by endothelial disruption and nitric oxide synthase (NOS) inhibition, indicating the involvement of both endothelium and vascular smooth muscle. In addition, the endothelium-dependent vasodilation, but not the endothelium-independent vasodilation, was blocked by BKCa inhibitor iberiotoxin (IbTX). Using human umbilical vein endothelial cells (HUVECs) as a model, we showed calycosin and formononetin induced dose-dependent outwardly rectifying K+ currents using whole cell patch clamp. These currents were blocked by tetraethylammonium chloride (TEACl), charybdotoxin (ChTX), or IbTX, but not apamin. We further demonstrated that both isoflavonoids significantly increased nitric oxide (NO) production and upregulated the activities and expressions of endothelial NOS (eNOS) and neuronal NOS (nNOS). These results suggested that calycosin and formononetin act as endothelial BKCa activators for mediating endothelium-dependent vasodilation through enhancing endothelium hyperpolarization and NO production. Since activation of BKCa plays a role in improving behavioral and cognitive disorders, we suggested that these two isoflavonoids could provide beneficial effects to cognitive disorders through vascular regulation.
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66
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Tseng HHL, Vong CT, Kwan YW, Lee SMY, Hoi MPM. TRPM2 regulates TXNIP-mediated NLRP3 inflammasome activation via interaction with p47 phox under high glucose in human monocytic cells. Sci Rep 2016; 6:35016. [PMID: 27731349 PMCID: PMC5059733 DOI: 10.1038/srep35016] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/21/2016] [Indexed: 12/15/2022] Open
Abstract
Excessive production of reactive oxygen species (ROS) induced by hyperglycemia increased the secretion of interleukin-1β (IL-1β), which contributes to the pathogenesis of diabetes and its complications. Although high glucose (HG)-induced oxidative stress and aberrant Ca2+ channels activity causes an increase in transmembrane Ca2+ influx, however the relative contribution of Transient receptor potential (TRP) channels is not well studied. Here, we identified that HG (30 mM glucose for 48 h) induced the activation of the NLRP3-ASC inflammasome, leading to caspase-1 activation, and IL-1β and IL-18 secretion in human monocytic cell lines. Moreover, we used a hyperglycemia model in U937 monocytes, showing that the activation of TRPM2 was augmented, and TRPM2-mediated Ca2+ influx was critical for NLRP3 inflammasome activation. This pathway involved NADPH oxidase-dependent ROS production and TXNIP-NLRP3 inflammasome pathway. Furthermore, the inhibition of TRPM2 reduced ROS production and lowered NADPH oxidase activity via cooperatively interaction with p47 phox in response to HG. These results provided a mechanistic linking between TRPM2-mediated Ca2+ influx and p47 phox signaling to induce excess ROS production and TXNIP-mediated NLRP3 inflammasome activation under HG, and suggested that TRPM2 represented a potential target for alleviating NLRP3 inflammasome activation related to hyperglycemia-induced oxidative stress in Type 2 diabetes Mellitus (T2DM).
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Affiliation(s)
- Hisa Hui Ling Tseng
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China
| | - Chi Teng Vong
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China
| | - Yiu Wa Kwan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Simon Ming-Yuen Lee
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China
| | - Maggie Pui Man Hoi
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Avenida da Universidade, Taipa, Macau, China
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67
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Li B, Gao TM. Functional Role of Mitochondrial and Nuclear BK Channels. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:163-91. [PMID: 27238264 DOI: 10.1016/bs.irn.2016.03.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BK channels are important for the regulation of many cell functions. The significance of plasma membrane BK channels in the control of action potentials, resting membrane potential, and neurotransmitter release is well established; however, the composition and functions of mitochondrial and nuclear BK (nBK) channels are largely unknown. In this chapter, we summarize the recent findings on the subcellular localization, biophysical, and pharmacological properties of mitochondrial and nBK channels and discuss their molecular identity and physiological functions.
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Affiliation(s)
- B Li
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - T-M Gao
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.
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68
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BKCa channel regulates calcium oscillations induced by alpha-2-macroglobulin in human myometrial smooth muscle cells. Proc Natl Acad Sci U S A 2016; 113:E2335-44. [PMID: 27044074 DOI: 10.1073/pnas.1516863113] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The large-conductance, voltage-gated, calcium (Ca(2+))-activated potassium channel (BKCa) plays an important role in regulating Ca(2+)signaling and is implicated in the maintenance of uterine quiescence during pregnancy. We used immunopurification and mass spectrometry to identify proteins that interact with BKCain myometrium samples from term pregnant (≥37 wk gestation) women. From this screen, we identified alpha-2-macroglobulin (α2M). We then used immunoprecipitation followed by immunoblot and the proximity ligation assay to confirm the interaction between BKCaand both α2M and its receptor, low-density lipoprotein receptor-related protein 1 (LRP1), in cultured primary human myometrial smooth muscle cells (hMSMCs). Single-channel electrophysiological recordings in the cell-attached configuration demonstrated that activated α2M (α2M*) increased the open probability of BKCain an oscillatory pattern in hMSMCs. Furthermore, α2M* caused intracellular levels of Ca(2+)to oscillate in oxytocin-primed hMSMCs. The initiation of oscillations required an interaction between α2M* and LRP1. By using Ca(2+)-free medium and inhibitors of various Ca(2+)signaling pathways, we demonstrated that the oscillations required entry of extracellular Ca(2+)through store-operated Ca(2+)channels. Finally, we found that the specific BKCablocker paxilline inhibited the oscillations, whereas the channel opener NS11021 increased the rate of these oscillations. These data demonstrate that α2M* and LRP1 modulate the BKCachannel in human myometrium and that BKCaand its immunomodulatory interacting partners regulate Ca(2+)dynamics in hMSMCs during pregnancy.
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69
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Singh H, Li M, Hall L, Chen S, Sukur S, Lu R, Caputo A, Meredith AL, Stefani E, Toro L. MaxiK channel interactome reveals its interaction with GABA transporter 3 and heat shock protein 60 in the mammalian brain. Neuroscience 2016; 317:76-107. [PMID: 26772433 PMCID: PMC4737998 DOI: 10.1016/j.neuroscience.2015.12.058] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/29/2015] [Accepted: 12/30/2015] [Indexed: 10/22/2022]
Abstract
Large conductance voltage and calcium-activated potassium (MaxiK) channels are activated by membrane depolarization and elevated cytosolic Ca(2+). In the brain, they localize to neurons and astrocytes, where they play roles such as resetting the membrane potential during an action potential, neurotransmitter release, and neurovascular coupling. MaxiK channels are known to associate with several modulatory proteins and accessory subunits, and each of these interactions can have distinct physiological consequences. To uncover new players in MaxiK channel brain physiology, we applied a directed proteomic approach and obtained MaxiK channel pore-forming α subunit brain interactome using specific antibodies. Controls included immunoprecipitations with rabbit immunoglobulin G (IgG) and with anti-MaxiK antibodies in wild type and MaxiK channel knockout mice (Kcnma1(-/-)), respectively. We have found known and unreported interactive partners that localize to the plasma membrane, extracellular space, cytosol and intracellular organelles including mitochondria, nucleus, endoplasmic reticulum and Golgi apparatus. Localization of MaxiK channel to mitochondria was further confirmed using purified brain mitochondria colabeled with MitoTracker. Independent proof of MaxiK channel interaction with previously unidentified partners is given for GABA transporter 3 (GAT3) and heat shock protein 60 (HSP60). In human embryonic kidney 293 cells containing SV40 T-antigen (HEK293T) cells, both GAT3 and HSP60 coimmunoprecipitated and colocalized with MaxiK channel; colabeling was observed mainly at the cell periphery with GAT3 and intracellularly with HSP60 with protein proximity indices of ∼ 0.6 and ∼ 0.4, respectively. In rat primary hippocampal neurons, colocalization index was identical for GAT3 (∼ 0.6) and slightly higher for HSP60 (∼ 0.5) association with MaxiK channel. The results of this study provide a complete interactome of MaxiK channel the mouse brain, further establish the localization of MaxiK channel in the mouse brain mitochondria and demonstrate the interaction of MaxiK channel with GAT3 and HSP60 in neurons. The interaction of MaxiK channel with GAT3 opens the possibility of a role of MaxiK channel in GABA homeostasis and signaling.
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Affiliation(s)
- H Singh
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA; Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - M Li
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - L Hall
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - S Chen
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - S Sukur
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
| | - R Lu
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA.
| | - A Caputo
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
| | - A L Meredith
- Department of Physiology, University of Maryland, Baltimore, MD 21201, USA.
| | - E Stefani
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA; Department of Physiology, University of California, Los Angeles, CA 90095, USA; Brain Research Institute, University of California, Los Angeles, CA 90095, USA.
| | - L Toro
- Department of Anesthesiology, University of California, Los Angeles, CA 90095, USA; Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095, USA; Brain Research Institute, University of California, Los Angeles, CA 90095, USA; Cardiovascular Research Laboratory, University of California, Los Angeles, CA 90095, USA.
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70
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Checchetto V, Teardo E, Carraretto L, Leanza L, Szabo I. Physiology of intracellular potassium channels: A unifying role as mediators of counterion fluxes? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1258-1266. [PMID: 26970213 DOI: 10.1016/j.bbabio.2016.03.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 12/28/2022]
Abstract
Plasma membrane potassium channels importantly contribute to maintain ion homeostasis across the cell membrane. The view is emerging that also those residing in intracellular membranes play pivotal roles for the coordination of correct cell function. In this review we critically discuss our current understanding of the nature and physiological tasks of potassium channels in organelle membranes in both animal and plant cells, with a special emphasis on their function in the regulation of photosynthesis and mitochondrial respiration. In addition, the emerging role of potassium channels in the nuclear membranes in regulating transcription will be discussed. The possible functions of endoplasmic reticulum-, lysosome- and plant vacuolar membrane-located channels are also referred to. Altogether, experimental evidence obtained with distinct channels in different membrane systems points to a possible unifying function of most intracellular potassium channels in counterbalancing the movement of other ions including protons and calcium and modulating membrane potential, thereby fine-tuning crucial cellular processes. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-7, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Vanessa Checchetto
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy; Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35131 Italy
| | - Enrico Teardo
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy
| | - Luca Carraretto
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy
| | - Luigi Leanza
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy
| | - Ildiko Szabo
- Department of Biology, University of Padova, Viale G. Colombo 3, Padova 35131, Italy; CNR Institute of Neuroscience, University of Padova, Viale G. Colombo 3, Padova 35131, Italy.
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71
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Zemen BG, Lai MH, Whitt JP, Khan Z, Zhao G, Meredith AL. Generation of Kcnma1fl-tdTomato, a conditional deletion of the BK channel α subunit in mouse. Physiol Rep 2015; 3:e12612. [PMID: 26537348 PMCID: PMC4673641 DOI: 10.14814/phy2.12612] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 10/09/2015] [Accepted: 10/13/2015] [Indexed: 11/24/2022] Open
Abstract
BK large conductance calcium-activated K(+) channels (KC a1.1) are expressed widely across many tissues, contributing to systemic regulation of cardiovascular, neurological, and other specialized physiological functions. The pore-forming α subunit is encoded by the Kcnma1 gene, originally named mSlo1 in mouse and slowpoke in Drosophila. Global deletion in mouse (Kcnma1(-/-)) produces a plethora of defects in neuron and muscle excitability, as well as other phenotypes related to channel function in nonexcitable cells. While homozygous null mice are viable, the ubiquitous loss of BK function has complicated the interpretation of phenotypes involving the interaction of multiple cell types which independently express BK channels. Here, we report the generation of a targeted allele for conditional inactivation of Kcnma1 using the Cre-loxP system (Kcnma1(fl)-tdTomato). Cre-mediated recombination generates a null allele, and BK currents were not detectable in neurons and muscle cells from Nestin-Cre; Kcnma1(fl/fl) and SM22α-Cre; Kcnma1(fl/fl) mice, respectively. tdTomato expression was detected in Cre-expressing tissues, but not in Cre-negative controls. These data demonstrate the utility of Kcnma1(fl)-tdTomato for conditional deletion of the BK channel, facilitating the understanding of tissue-specific contributions to physiological function in vivo.
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Affiliation(s)
- Betsir G Zemen
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Michael H Lai
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Joshua P Whitt
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Zulqarnain Khan
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Guiling Zhao
- Center of BioMedical Engineering and Technology and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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72
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Hermann A, Sitdikova GF, Weiger TM. Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels. Biomolecules 2015; 5:1870-911. [PMID: 26287261 PMCID: PMC4598779 DOI: 10.3390/biom5031870] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/17/2015] [Accepted: 07/20/2015] [Indexed: 01/13/2023] Open
Abstract
All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences.
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Affiliation(s)
- Anton Hermann
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
| | - Guzel F Sitdikova
- Department of Physiology of Man and Animals, Kazan Federal University, Kazan 420008, Russia.
| | - Thomas M Weiger
- Department of Cell Biology, Division of Cellular and Molecular Neurobiology, University of Salzburg, Salzburg 5020, Austria.
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73
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Joyal JS, Bhosle VK, Chemtob S. Subcellular G-protein coupled receptor signaling hints at greater therapeutic selectivity. Expert Opin Ther Targets 2015; 19:717-21. [DOI: 10.1517/14728222.2015.1042365] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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74
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Leo A, Citraro R, Constanti A, De Sarro G, Russo E. Are big potassium-type Ca2+-activated potassium channels a viable target for the treatment of epilepsy? Expert Opin Ther Targets 2015; 19:911-26. [DOI: 10.1517/14728222.2015.1026258] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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75
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Chung NC, Huang YH, Chang CH, Liao JC, Yang CH, Chen CC, Liu IY. Behavior training reverses asymmetry in hippocampal transcriptome of the cav3.2 knockout mice. PLoS One 2015; 10:e0118832. [PMID: 25768289 PMCID: PMC4358833 DOI: 10.1371/journal.pone.0118832] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 01/23/2015] [Indexed: 12/13/2022] Open
Abstract
Homozygous Cav3.2 knockout mice, which are defective in the pore-forming subunit of a low voltage activated T-type calcium channel, have been documented to show impaired maintenance of late-phase long-term potentiation (L-LTP) and defective retrieval of context-associated fear memory. To investigate the role of Cav3.2 in global gene expression, we performed a microarray transcriptome study on the hippocampi of the Cav3.2-/- mice and their wild-type littermates, either naïve (untrained) or trace fear conditioned. We found a significant left-right asymmetric effect on the hippocampal transcriptome caused by the Cav3.2 knockout. Between the naive Cav3.2-/- and the naive wild-type mice, 3522 differentially expressed genes (DEGs) were found in the left hippocampus, but only 4 DEGs were found in the right hippocampus. Remarkably, the effect of Cav3.2 knockout was partially reversed by trace fear conditioning. The number of DEGs in the left hippocampus was reduced to 6 in the Cav3.2 knockout mice after trace fear conditioning, compared with the wild-type naïve mice. To our knowledge, these results demonstrate for the first time the asymmetric effects of the Cav3.2 and its partial reversal by behavior training on the hippocampal transcriptome.
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Affiliation(s)
- Ni-Chun Chung
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien, Taiwan
| | - Ying-Hsueh Huang
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan
| | - Chuan-Hsiung Chang
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan
| | - James C. Liao
- Department of Chemical and Biomolecular Engineering, University of California Los Angeles, Los Angeles, California, United States of America
| | - Chih-Hsien Yang
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan
| | - Chien-Chang Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Ingrid Y. Liu
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien, Taiwan
- Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan
- * E-mail:
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76
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Yang H, Zhang G, Cui J. BK channels: multiple sensors, one activation gate. Front Physiol 2015; 6:29. [PMID: 25705194 PMCID: PMC4319557 DOI: 10.3389/fphys.2015.00029] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 01/19/2015] [Indexed: 01/01/2023] Open
Abstract
Ion transport across cell membranes is essential to cell communication and signaling. Passive ion transport is mediated by ion channels, membrane proteins that create ion conducting pores across cell membrane to allow ion flux down electrochemical gradient. Under physiological conditions, majority of ion channel pores are not constitutively open. Instead, structural region(s) within these pores breaks the continuity of the aqueous ion pathway, thereby serves as activation gate(s) to control ions flow in and out. To achieve spatially and temporally regulated ion flux in cells, many ion channels have evolved sensors to detect various environmental stimuli or the metabolic states of the cell and trigger global conformational changes, thereby dynamically operate the opening and closing of their activation gate. The sensors of ion channels can be broadly categorized as chemical sensors and physical sensors to respond to chemical (such as neural transmitters, nucleotides and ions) and physical (such as voltage, mechanical force and temperature) signals, respectively. With the rapidly growing structural and functional information of different types of ion channels, it is now critical to understand how ion channel sensors dynamically control their gates at molecular and atomic level. The voltage and Ca2+ activated BK channels, a K+ channel with an electrical sensor and multiple chemical sensors, provide a unique model system for us to understand how physical and chemical energy synergistically operate its activation gate.
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Affiliation(s)
- Huanghe Yang
- Ion Channel Research Unit, Duke University Medical Center Durham, NC, USA ; Department of Biochemistry, Duke University Medical Center Durham, NC, USA
| | - Guohui Zhang
- Department of Biomedical Engineering, Washington University in Saint Louis St. Louis, MO, USA
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in Saint Louis St. Louis, MO, USA ; Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis St. Louis, MO, USA ; Center for The Investigation of Membrane Excitability Disorders, Washington University in Saint Louis St. Louis, MO, USA
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77
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Age-related changes in large-conductance calcium-activated potassium channels in mammalian circadian clock neurons. Neurobiol Aging 2015; 36:2176-83. [PMID: 25735218 DOI: 10.1016/j.neurobiolaging.2014.12.040] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/09/2014] [Accepted: 12/09/2014] [Indexed: 01/18/2023]
Abstract
Aging impairs the function of the suprachiasmatic nucleus (SCN, the central mammalian clock), leading to a decline in the circadian rhythm of many physiological processes, including sleep-wake rhythms. Recent studies have found evidence of age-related changes in the circadian regulation of potassium currents; these changes presumably lead to a decrease in the SCN's electrical rhythm amplitude. Current through large-conductance Ca(2+)-activated K(+) (BK) channels promote rhythmicity in both SCN neuronal activity and behavior. In many neuron types, changes in BK activity are correlated with changes in intracellular Ca(2+) concentration ([Ca(2+)]i). We performed patch-clamp recordings of SCN neurons in aged mice and observed that the circadian modulation of BK channel activity was lost because of a reduction in BK currents during the night. This reduced current diminished the afterhyperpolarization, depolarized the resting membrane potential, widened the action potential, and increased [Ca(2+)]i. These data suggest that reduced BK current increases [Ca(2+)]i by altering the action potential waveform, possibly contributing to the observed age-related phenotype.
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78
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Meijer JH, Michel S. Neurophysiological Analysis of the Suprachiasmatic Nucleus. Methods Enzymol 2015; 552:75-102. [DOI: 10.1016/bs.mie.2014.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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79
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Macromolecular transport in synapse to nucleus communication. Trends Neurosci 2014; 38:108-16. [PMID: 25534890 DOI: 10.1016/j.tins.2014.12.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/01/2014] [Indexed: 12/21/2022]
Abstract
Local signaling events at synapses or axon terminals must be communicated to the nucleus to elicit transcriptional responses. The lengths of neuronal processes pose a significant challenge for such intracellular communication. This challenge is met by mechanisms ranging from rapid signals encoded in calcium waves to slower macromolecular signaling complexes carried by molecular motors. Here we summarize recent findings on macromolecular signaling from the synapse to the nucleus, in comparison to those employed in injury signaling along axons. A number of common themes emerge, including combinatorial signal encoding by post-translational mechanisms such as differential phosphorylation and proteolysis, and conserved roles for importins in coordinating signaling complexes. Neurons may integrate ionic flux with motor-transported signals as a temporal code for synaptic plasticity signaling.
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80
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Curci A, Mele A, Camerino GM, Dinardo MM, Tricarico D. The large conductance Ca(2+) -activated K(+) (BKCa) channel regulates cell proliferation in SH-SY5Y neuroblastoma cells by activating the staurosporine-sensitive protein kinases. Front Physiol 2014; 5:476. [PMID: 25538629 PMCID: PMC4260485 DOI: 10.3389/fphys.2014.00476] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 11/20/2014] [Indexed: 12/31/2022] Open
Abstract
Here we investigated on the role of the calcium activated K(+)-channels(BKCa) on the regulation of the neuronal viability. Recordings of the K(+)-channel current were performed using patch-clamp technique in human neuroblastoma cells (SH-SY5Y) in parallel with measurements of the cell viability in the absence or presence of the BKCa channel blockers iberiotoxin(IbTX) and tetraethylammonium (TEA) and the BKCa channel opener NS1619. Protein kinase C/A (PKC, PKA) activities in the cell lysate were investigated in the presence/absence of drugs. The whole-cell K(+)-current showed a slope conductance calculated at negative membrane potentials of 126.3 pS and 1.717 nS(n = 46) following depolarization. The intercept of the I/V curve was -33 mV. IbTX(10(-8) - 4 × 10(-7) M) reduced the K(+)-current at +30 mV with an IC50 of 1.85 × 10(-7) M and an Imax of -46% (slope = 2.198) (n = 21). NS1619(10-100 × 10(-6) M) enhanced the K(+)-current of +141% (n = 6), at -10 mV(Vm). TEA(10(-5)-10(-3) M) reduced the K(+)-current with an IC50 of 3.54 × 10(-5) M and an Imax of -90% (slope = 0.95) (n = 5). A concentration-dependent increase of cell proliferation was observed with TEA showing a maximal proliferative effect(MPE) of +38% (10(-4) M). IbTX showed an MPE of +42% at 10(-8) M concentration, reducing it at higher concentrations. The MPE of the NS1619(100 × 10(-6) M) was +42%. The PKC inhibitor staurosporine (0.2-2 × 10(-6) M) antagonized the proliferative actions of IbTX and TEA. IbTX (10 × 10(-9) M), TEA (100 × 10(-6) M), and the NS1619 significantly enhanced the PKC and PKA activities in the cell lysate with respect to the controls. These results suggest that BKCa channel regulates proliferation of the SH-SY5Y cells through PKC and PKA protein kinases.
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Affiliation(s)
- Angela Curci
- Department of Pharmacy-Drug Science, University of Bari "Aldo Moro" Bari, Italy
| | - Antonietta Mele
- Department of Pharmacy-Drug Science, University of Bari "Aldo Moro" Bari, Italy
| | | | | | - Domenico Tricarico
- Department of Pharmacy-Drug Science, University of Bari "Aldo Moro" Bari, Italy
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81
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Dopico AM, Bukiya AN, Martin GE. Ethanol modulation of mammalian BK channels in excitable tissues: molecular targets and their possible contribution to alcohol-induced altered behavior. Front Physiol 2014; 5:466. [PMID: 25538625 PMCID: PMC4256990 DOI: 10.3389/fphys.2014.00466] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 11/13/2014] [Indexed: 11/30/2022] Open
Abstract
In most tissues, the function of Ca2+- and voltage-gated K+ (BK) channels is modified in response to ethanol concentrations reached in human blood during alcohol intoxication. In general, modification of BK current from ethanol-naïve preparations in response to brief ethanol exposure results from changes in channel open probability without modification of unitary conductance or change in BK protein levels in the membrane. Protracted and/or repeated ethanol exposure, however, may evoke changes in BK expression. The final ethanol effect on BK open probability leading to either BK current potentiation or BK current reduction is determined by an orchestration of molecular factors, including levels of activating ligand (Ca2+i), BK subunit composition and post-translational modifications, and the channel's lipid microenvironment. These factors seem to allosterically regulate a direct interaction between ethanol and a recognition pocket of discrete dimensions recently mapped to the channel-forming (slo1) subunit. Type of ethanol exposure also plays a role in the final BK response to the drug: in several central nervous system regions (e.g., striatum, primary sensory neurons, and supraoptic nucleus), acute exposure to ethanol reduces neuronal excitability by enhancing BK activity. In contrast, protracted or repetitive ethanol administration may alter BK subunit composition and membrane expression, rendering the BK complex insensitive to further ethanol exposure. In neurohypophyseal axon terminals, ethanol potentiation of BK channel activity leads to a reduction in neuropeptide release. In vascular smooth muscle, however, ethanol inhibition of BK current leads to cell contraction and vascular constriction.
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Affiliation(s)
- Alex M Dopico
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center Memphis, TN, USA
| | - Anna N Bukiya
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center Memphis, TN, USA
| | - Gilles E Martin
- Department of Psychiatry, The University of Massachusetts Medical School Worcester, MA, USA
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82
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Li B, Jie W, Huang L, Wei P, Li S, Luo Z, Friedman AK, Meredith AL, Han MH, Zhu XH, Gao TM. Erratum: Corrigendum: Nuclear BK channels regulate gene expression via the control of nuclear calcium signaling. Nat Neurosci 2014. [DOI: 10.1038/nn1214-1841b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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83
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Bettinger JC, Davies AG. The role of the BK channel in ethanol response behaviors: evidence from model organism and human studies. Front Physiol 2014; 5:346. [PMID: 25249984 PMCID: PMC4158801 DOI: 10.3389/fphys.2014.00346] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 08/22/2014] [Indexed: 11/30/2022] Open
Abstract
Alcohol abuse is a significant public health problem. Understanding the molecular effects of ethanol is important for the identification of at risk individuals, as well as the development of novel pharmacotherapies. The large conductance calcium sensitive potassium (BK) channel has emerged as an important player in the behavioral response to ethanol in genetic studies in several model organisms and in humans. The BK channel, slo-1, was identified in a forward genetics screen as a major ethanol target in C. elegans for the effects of ethanol on locomotion and egg-laying behaviors. Regulation of the expression of the BK channel, slo, in Drosophila underlies the development of rapid tolerance to ethanol and benzyl alcohol sedation. Rodent expression studies of the BK-encoding KCNMA1 gene have identified regulation of mRNA levels in response to ethanol exposure, and knock out studies in mice have demonstrated that the β subunits of the BK channel, β1 and β4, can modulate ethanol sensitivity of the channel in electrophysiological preparations, and can influence drinking behavior. In human genetics studies, both KCNMA1 and the genes encoding β subunits of the BK channel have been associated with alcohol dependence. This review describes the genetic data for a role for BK channels in mediating behavioral responses to ethanol across these species.
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Affiliation(s)
- Jill C Bettinger
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA, USA
| | - Andrew G Davies
- Department of Pharmacology and Toxicology, Virginia Commonwealth University Richmond, VA, USA
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