1
|
Jafari Afshar E, Gholami N, Samimisedeh P, MozafaryBazargany M, Tayebi A, Memari A, Yazdani S, Rastad H. Utility of electrocardiogram to predict the occurrence of the no-reflow phenomenon in patients undergoing primary percutaneous coronary intervention (PPCI): a systematic review and meta-analysis. Front Cardiovasc Med 2024; 10:1295964. [PMID: 38283173 PMCID: PMC10813196 DOI: 10.3389/fcvm.2023.1295964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 12/14/2023] [Indexed: 01/30/2024] Open
Abstract
Background The no-reflow phenomenon affects about one out of five patients undergoing Primary Percutaneous Coronary Intervention (PPCI). As the prolonged no-reflow phenomenon is linked with unfavorable outcomes, making early recognition is crucial for effective management and improved clinical outcomes in these patients. Our review study aimed to determine whether electrocardiogram (ECG) findings before PCI could serve as predictors for the occurrence of the no-reflow phenomenon. Methods and materials We systematically searched MEDLINE, Scopus, and Embase to identify relevant studies. The random-effect model using inverse variance and Mantel-Haenszel methods were used to pool the standardized mean differences (SMD) and odds ratios (OR), respectively. Result Sixteen eligible articles (1,473 cases and 4,264 controls) were included in this study. Based on our meta-analysis of baseline ECG findings, the no-reflow group compared to the control group significantly had a higher frequency of fragmented QRS complexes (fQRS) (OR (95% CI): 1.35 (0.32-2.38), P-value = 0.01), and Q-waves (OR (95% CI): 1.97 (1.01-2.94), P-value <0.001). Also, a longer QRS duration (QRSD) (SMD (95% CI): 0.72 (0.21, 1.23), p-value <0.001) and R wave peak time (RWPT) (SMD (95% CI): 1.36 (0.8, 1.93), P < 0.001) were seen in the no-reflow group. The two groups had no significant difference regarding P wave peak time (PWPT), and P wave maximum duration (Pmax) on baseline ECG. Conclusion Our findings suggest that prolonged QRSD, delayed RWPT, higher fQRS prevalence, and the presence of a Q wave on baseline ECG may predict the occurrence of the no-reflow phenomenon in patients undergoing PPCI.
Collapse
Affiliation(s)
- Elmira Jafari Afshar
- Cardiovascular Research Center, Alborz University of Medical Sciences, Alborz, Iran
| | - Niloofar Gholami
- Cardiovascular Research Center, Alborz University of Medical Sciences, Alborz, Iran
| | - Parham Samimisedeh
- Cardiovascular Research Center, Alborz University of Medical Sciences, Alborz, Iran
| | | | - Amirhossein Tayebi
- Cardiovascular Research Center, Alborz University of Medical Sciences, Alborz, Iran
| | - Amirhossein Memari
- Cardiovascular Research Center, Alborz University of Medical Sciences, Alborz, Iran
| | - Shahrooz Yazdani
- Cardiovascular Research Center, Alborz University of Medical Sciences, Alborz, Iran
| | - Hadith Rastad
- Cardiovascular Research Center, Alborz University of Medical Sciences, Alborz, Iran
| |
Collapse
|
2
|
Hori T, Takamori S. Physiological Perspectives on Molecular Mechanisms and Regulation of Vesicular Glutamate Transport: Lessons From Calyx of Held Synapses. Front Cell Neurosci 2022; 15:811892. [PMID: 35095427 PMCID: PMC8793065 DOI: 10.3389/fncel.2021.811892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/07/2021] [Indexed: 12/02/2022] Open
Abstract
Accumulation of glutamate, the primary excitatory neurotransmitter in the mammalian central nervous system, into presynaptic synaptic vesicles (SVs) depends upon three vesicular glutamate transporters (VGLUTs). Since VGLUTs are driven by a proton electrochemical gradient across the SV membrane generated by vacuolar-type H+-ATPases (V-ATPases), the rate of glutamate transport into SVs, as well as the amount of glutamate in SVs at equilibrium, are influenced by activities of both VGLUTs and V-ATPase. Despite emerging evidence that suggests various factors influencing glutamate transport by VGLUTs in vitro, little has been reported in physiological or pathological contexts to date. Historically, this was partially due to a lack of appropriate methods to monitor glutamate loading into SVs in living synapses. Furthermore, whether or not glutamate refilling of SVs can be rate-limiting for synaptic transmission is not well understood, primarily due to a lack of knowledge concerning the time required for vesicle reuse and refilling during repetitive stimulation. In this review, we first introduce a unique electrophysiological method to monitor glutamate refilling by VGLUTs in a giant model synapse from the calyx of Held in rodent brainstem slices, and we discuss the advantages and limitations of the method. We then introduce the current understanding of factors that potentially alter the amount and rate of glutamate refilling of SVs in this synapse, and discuss open questions from physiological viewpoints.
Collapse
Affiliation(s)
- Tetsuya Hori
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- *Correspondence: Tetsuya Hori Shigeo Takamori
| | - Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University, Kyoto, Japan
- *Correspondence: Tetsuya Hori Shigeo Takamori
| |
Collapse
|
3
|
Schenck S, Kunz L, Sahlender D, Pardon E, Geertsma ER, Savtchouk I, Suzuki T, Neldner Y, Štefanić S, Steyaert J, Volterra A, Dutzler R. Generation and Characterization of Anti-VGLUT Nanobodies Acting as Inhibitors of Transport. Biochemistry 2017; 56:3962-3971. [DOI: 10.1021/acs.biochem.7b00436] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Stephan Schenck
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Laura Kunz
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Daniela Sahlender
- Department
of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Els Pardon
- VIB
Center for Structural Biology, VIB, 1050 Brussels, Belgium
- Structural
Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Eric R. Geertsma
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Institute
of Biochemistry, Biocenter, Goethe-University Frankfurt, Max-von-Laue-Straβe
9, 60438 Frankfurt
am Main, Germany
| | - Iaroslav Savtchouk
- Department
of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Toshiharu Suzuki
- Department
of Applied Chemistry, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yvonne Neldner
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Saša Štefanić
- Institute
of Parasitology, University of Zurich, Winterthurerstrasse 266a, 8057 Zurich, Switzerland
| | - Jan Steyaert
- VIB
Center for Structural Biology, VIB, 1050 Brussels, Belgium
- Structural
Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Andrea Volterra
- Department
of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Raimund Dutzler
- Department
of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| |
Collapse
|
4
|
Kehrl J, Althaus JC, Showalter HD, Rudzinski DM, Sutton MA, Ueda T. Vesicular Glutamate Transporter Inhibitors: Structurally Modified Brilliant Yellow Analogs. Neurochem Res 2017; 42:1823-1832. [DOI: 10.1007/s11064-017-2198-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 12/22/2022]
|
5
|
Takamori S. Presynaptic Molecular Determinants of Quantal Size. Front Synaptic Neurosci 2016; 8:2. [PMID: 26903855 PMCID: PMC4744840 DOI: 10.3389/fnsyn.2016.00002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/25/2016] [Indexed: 01/22/2023] Open
Abstract
The quantal hypothesis for the release of neurotransmitters at the chemical synapse has gained wide acceptance since it was first worked out at the motor endplate in frog skeletal muscle in the 1950’s. Considering the morphological identification of synaptic vesicles (SVs) at the nerve terminals that appeared to be homogeneous in size, the hypothesis proposed that signal transduction at synapses is mediated by the release of neurotransmitters packed in SVs that are individually uniform in size; the amount of transmitter in a synaptic vesicle is called a quantum. Although quantal size—the amplitude of the postsynaptic response elicited by the release of neurotransmitters from a single vesicle—clearly depends on the number and sensitivity of the postsynaptic receptors, accumulating evidence has also indicated that the amount of neurotransmitters stored in SVs can be altered by various presynaptic factors. Here, I provide an overview of the concepts and underlying presynaptic molecular underpinnings that may regulate quantal size.
Collapse
Affiliation(s)
- Shigeo Takamori
- Laboratory of Neural Membrane Biology, Graduate School of Brain Science, Doshisha University Kyoto, Japan
| |
Collapse
|
6
|
|
7
|
Hackett JT, Ueda T. Glutamate Release. Neurochem Res 2015; 40:2443-60. [PMID: 26012367 DOI: 10.1007/s11064-015-1622-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 05/17/2015] [Accepted: 05/20/2015] [Indexed: 12/18/2022]
Abstract
Our aim was to review the processes of glutamate release from both biochemical and neurophysiological points of view. A large body of evidence now indicates that glutamate is specifically accumulated into synaptic vesicles, which provides strong support for the concept that glutamate is released from synaptic vesicles and is the major excitatory neurotransmitter. Evidence suggests the notion that synaptic vesicles, in order to sustain the neurotransmitter pool of glutamate, are endowed with an efficient mechanism for vesicular filling of glutamate. Glutamate-loaded vesicles undergo removal of Synapsin I by CaM kinase II-mediated phosphorylation, transforming to the release-ready pool. Vesicle docking to and fusion with the presynaptic plasma membrane are thought to be mediated by the SNARE complex. The Ca(2+)-dependent step in exocytosis is proposed to be mediated by synaptotagmin.
Collapse
Affiliation(s)
- John T Hackett
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, 22908-0736, USA
| | - Tetsufumi Ueda
- Molecular and Behavioral Neuroscience Institute, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200, USA. .,Department of Pharmacology, Medical School, The University of Michigan, Ann Arbor, MI, 48109, USA. .,Department of Psychiatry, Medical School, The University of Michigan, Ann Arbor, MI, 48109, USA.
| |
Collapse
|
8
|
Yadav R, Yan X, Maixner DW, Gao M, Weng HR. Blocking the GABA transporter GAT-1 ameliorates spinal GABAergic disinhibition and neuropathic pain induced by paclitaxel. J Neurochem 2015; 133:857-69. [PMID: 25827582 DOI: 10.1111/jnc.13103] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 03/02/2015] [Accepted: 03/05/2015] [Indexed: 11/24/2022]
Abstract
Paclitaxel is a chemotherapeutic agent widely used for treating carcinomas. Patients receiving paclitaxel often develop neuropathic pain and have a reduced quality of life which hinders the use of this life-saving drug. In this study, we determined the role of GABA transporters in the genesis of paclitaxel-induced neuropathic pain using behavioral tests, electrophysiology, and biochemical techniques. We found that tonic GABA receptor activities in the spinal dorsal horn were reduced in rats with neuropathic pain induced by paclitaxel. In normal controls, tonic GABA receptor activities were mainly controlled by the GABA transporter GAT-1 but not GAT-3. In the spinal dorsal horn, GAT-1 was expressed at presynaptic terminals and astrocytes while GAT-3 was only expressed in astrocytes. In rats with paclitaxel-induced neuropathic pain, the protein expression of GAT-1 was increased while GAT-3 was decreased. This was concurrently associated with an increase in global GABA uptake. The paclitaxel-induced attenuation of GABAergic tonic inhibition was ameliorated by blocking GAT-1 but not GAT-3 transporters. Paclitaxel-induced neuropathic pain was significantly attenuated by the intrathecal injection of a GAT-1 inhibitor. These findings suggest that targeting GAT-1 transporters for reversing disinhibition in the spinal dorsal horn may be a useful approach for treating paclitaxel-induced neuropathic pain. Patients receiving paclitaxel for cancer therapy often develop neuropathic pain and have a reduced quality of life. In this study, we demonstrated that animals treated with paclitaxel develop neuropathic pain, have enhancements of GABA transporter-1 protein expression and global GABA uptake, as well as suppression of GABAergic tonic inhibition in the spinal dorsal horn. Pharmacological inhibition of GABA transporter-1 ameliorates the paclitaxel-induced suppression of GABAergic tonic inhibition and neuropathic pain. Thus, targeting GAT-1 transporters for reversing GABAergic disinhibition in the spinal dorsal horn could be a useful approach for treating paclitaxel-induced neuropathic pain.
Collapse
Affiliation(s)
- Ruchi Yadav
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, Athens, Georgia, USA
| | - Xisheng Yan
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, Athens, Georgia, USA.,Department of Cardiovascular Medicine, the Third Hospital of Wuhan, Wuhan, Hubei Province, China
| | - Dylan W Maixner
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, Athens, Georgia, USA
| | - Mei Gao
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, Athens, Georgia, USA
| | - Han-Rong Weng
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, Athens, Georgia, USA
| |
Collapse
|
9
|
Tamura Y, Ogita K, Ueda T. A new VGLUT-specific potent inhibitor: pharmacophore of Brilliant Yellow. Neurochem Res 2014; 39:117-28. [PMID: 24248859 PMCID: PMC4025951 DOI: 10.1007/s11064-013-1196-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 10/26/2022]
Abstract
The increased concentration of glutamate in synaptic vesicles, mediated by the vesicular glutamate transporter (VGLUT), is an initial vital step in glutamate synaptic transmission. Evidence indicates that aberrant overexpression of VGLUT is involved in certain pathophysiologies of the central nervous system. VGLUT is subject to inhibition by various types of agents. The most potent VGLUT-specific inhibitor currently known is Trypan Blue, which is highly charged, hence membrane-impermeable. We have sought a potent, VGLUT-specific agent amenable to easy modification to a membrane-permeable analog. We provide evidence that Brilliant Yellow exhibits potent, VGLUT-specific inhibition, with a Ki value of 12 nM. Based upon structure-activity relationship studies and molecular modeling, we have defined the potent inhibitory pharmacophore of Brilliant Yellow. This study provides new insight into development of a membrane-permeable agent to lead to specific blockade, with high potency, of accumulation of glutamate into synaptic vesicles in neurons.
Collapse
Affiliation(s)
- Yutaka Tamura
- Molecular and Behavioral Neuroscience Institute, Medical School, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109-2200, USA
| | - Kiyokazu Ogita
- Molecular and Behavioral Neuroscience Institute, Medical School, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109-2200, USA
| | - Tetsufumi Ueda
- Molecular and Behavioral Neuroscience Institute, Medical School, The University of Michigan, 109 Zina Pitcher Place, Ann Arbor, Michigan 48109-2200, USA
- Department of Pharmacology, Medical School, The University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Psychiatry, Medical School, The University of Michigan, Ann Arbor, Michigan 48109, USA
| |
Collapse
|
10
|
Reimer RJ. SLC17: a functionally diverse family of organic anion transporters. Mol Aspects Med 2013; 34:350-9. [PMID: 23506876 DOI: 10.1016/j.mam.2012.05.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 03/29/2012] [Indexed: 11/28/2022]
Abstract
Molecular studies have determined that the SLC17 transporters, a family of nine proteins initially implicated in phosphate transport, mediate the transport of organic anions. While their role in phosphate transport remains uncertain, it is now clear that the transport of organic anions facilitated by this family of proteins is involved in diverse processes ranging from the vesicular storage of the neurotransmitters, to urate metabolism, to the degradation and metabolism of glycoproteins.
Collapse
Affiliation(s)
- Richard J Reimer
- Neurogenetics Division Department of Neurology and Neurological Sciences, Stanford University School of Medicine, P211 MSLS, 1201 Welch Road, Stanford, CA 94305, USA.
| |
Collapse
|
11
|
Eiden LE, Weihe E. VMAT2: a dynamic regulator of brain monoaminergic neuronal function interacting with drugs of abuse. Ann N Y Acad Sci 2011; 1216:86-98. [PMID: 21272013 DOI: 10.1111/j.1749-6632.2010.05906.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The monoaminergic neuron, in particular the dopaminergic neuron, is central to mediating the hedonic and addictive properties of drugs of abuse. The effects of amphetamine (AMPH) and cocaine (COC), for example, depend on the ability to increase dopamine in the synapse, by effects on either the plasma membrane transporter DAT or the vesicular transporter for monoamine storage, VMAT2. The potential role of DAT as a target for AMPH and COC has been reviewed extensively. Here, we present VMAT2 as a target that enables the rewarding and addictive actions of these drugs, based on imaging, neurochemical, biochemical, cell biological, genetic, and immunohistochemical evidence. The presence of VMAT2 in noradrenergic, serotoninergic, histaminergic, and potentially trace aminergic neurons invites consideration of a wider role for aminergic neurotransmission in AMPH and COC abuse and addiction.
Collapse
Affiliation(s)
- Lee E Eiden
- Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA.
| | | |
Collapse
|
12
|
Rotta LN, Leszczinski DN, Brusque AM, Pereira P, Brum LF, Nogueira CW, Frizzo ME, Perry ML, Souza DO. Effects of undernutrition on glutamatergic parameters in the cerebral cortex of young rats. Physiol Behav 2008; 94:580-5. [DOI: 10.1016/j.physbeh.2008.03.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 03/13/2008] [Accepted: 03/21/2008] [Indexed: 11/26/2022]
|
13
|
Ogita K, Hirata K, Bole DG, Yoshida S, Tamura Y, Leckenby AM, Ueda T. Inhibition of vesicular glutamate storage and exocytotic release by Rose Bengal. J Neurochem 2008. [DOI: 10.1046/j.1471-4159.2001.00200.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
14
|
Chaudhry FA, Edwards RH, Fonnum F. Vesicular neurotransmitter transporters as targets for endogenous and exogenous toxic substances. Annu Rev Pharmacol Toxicol 2008; 48:277-301. [PMID: 17883368 DOI: 10.1146/annurev.pharmtox.46.120604.141146] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exocytotic release of neurotransmitters requires their accumulation inside preformed secretory vesicles. Distinct vesicular transport activities translocate classical transmitters into synaptic vesicles energized by a H+ electrochemical gradient (Delta(mu(H+))), with subtle but important differences in dependence on the electrical and chemical components. The vesicular transporters also interact with toxic compounds and drugs. They mediate neuroprotection by sequestering toxic compounds as well as neurotransmitters into vesicles, reducing their concentration in the cytosol where they may have detrimental effects. Both therapeutic agents and psychostimulants interfering with vesicular transport have yielded insight into the pathogenesis of psychiatric as well as neurodegenerative diseases. Thus, specific inhibitors have helped to characterize both the physiological role and mechanism of vesicular neurotransmitter transport.
Collapse
Affiliation(s)
- Farrukh A Chaudhry
- Centre for Molecular Biology and Neuroscience, The Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway.
| | | | | |
Collapse
|
15
|
Chaudhry FA, Boulland JL, Jenstad M, Bredahl MKL, Edwards RH. Pharmacology of neurotransmitter transport into secretory vesicles. Handb Exp Pharmacol 2008:77-106. [PMID: 18064412 DOI: 10.1007/978-3-540-74805-2_4] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Many neuropsychiatric disorders appear to involve a disturbance of chemical neurotransmission, and the mechanism of available therapeutic agents supports this impression. Postsynaptic receptors have received considerable attention as drug targets, but some of the most successful agents influence presynaptic processes, in particular neurotransmitter reuptake. The pharmacological potential of many other presynaptic elements, and in particular the machinery responsible for loading transmitter into vesicles, has received only limited attention. The similarity of vesicular transporters to bacterial drug resistance proteins and the increasing evidence for regulation of vesicle filling and recycling suggest that the pharmacological potential of vesicular transporters has been underestimated. In this review, we discuss the pharmacological effects of psychostimulants and therapeutic agents on transmitter release.
Collapse
Affiliation(s)
- Farrukh A Chaudhry
- The Biotechnology Centre of Oslo, University of Oslo, 1125, Blindern, Oslo, 0317, Norway.
| | | | | | | | | |
Collapse
|
16
|
Abstract
Changes in the response to release of a single synaptic vesicle have generally been attributed to postsynaptic modification of receptor sensitivity, but considerable evidence now demonstrates that alterations in vesicle filling also contribute to changes in quantal size. Receptors are not saturated at many synapses, and changes in the amount of transmitter per vesicle contribute to the physiological regulation of release. On the other hand, the presynaptic factors that determine quantal size remain poorly understood. Aside from regulation of the fusion pore, these mechanisms fall into two general categories: those that affect the accumulation of transmitter inside a vesicle and those that affect vesicle size. This review will summarize current understanding of the neurotransmitter cycle and indicate basic, unanswered questions about the presynaptic regulation of quantal size.
Collapse
Affiliation(s)
- Robert H Edwards
- Department of Neurology and Physiology, UCSF School of Medicine, San Francisco, CA 94158-2517, USA.
| |
Collapse
|
17
|
Meary F, Metral S, Ferreira C, Eladari D, Colin Y, Lecomte MC, Nicolas G. A mutant alphaII-spectrin designed to resist calpain and caspase cleavage questions the functional importance of this process in vivo. J Biol Chem 2007; 282:14226-37. [PMID: 17374614 DOI: 10.1074/jbc.m700028200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
alpha- and beta-spectrins are components of molecular scaffolds located under the lipid bilayer and named membrane skeletons. Disruption of these scaffolds through mutations in spectrins demonstrated that they are involved in the membrane localization or the maintenance of proteins associated with them. The ubiquitous alphaII-spectrin chain bears in its central region a unique domain that is sensitive to several proteases such as calpains or caspases. The conservation of this region in vertebrates suggests that the proteolysis of alphaII-spectrin by these enzymes could be involved in important functions. To assess the role of alphaII-spectrin cleavage in vivo, we generated a murine model in which the exons encoding the region defining this cleavage sensitivity were disrupted by gene targeting. Surprisingly, homozygous mice expressing this mutant alphaII-spectrin appeared healthy, bred normally, and had no histological anomaly. Remarkably, the mutant alphaII-spectrin assembles correctly into the membrane skeleton, thus challenging the notion that this region is required for the stable biogenesis of the membrane skeleton in nonerythroid cells. Our finding also argues against a critical role of this particular alphaII-spectrin cleavage in either major cellular functions or in normal development.
Collapse
|
18
|
Winter S, Brunk I, Walther DJ, Höltje M, Jiang M, Peter JU, Takamori S, Jahn R, Birnbaumer L, Ahnert-Hilger G. Galphao2 regulates vesicular glutamate transporter activity by changing its chloride dependence. J Neurosci 2006; 25:4672-80. [PMID: 15872115 PMCID: PMC6725018 DOI: 10.1523/jneurosci.0549-05.2005] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Classical neurotransmitters, including monoamines, acetylcholine, glutamate, GABA, and glycine, are loaded into synaptic vesicles by means of specific transporters. Vesicular monoamine transporters are under negative regulation by alpha subunits of trimeric G-proteins, including Galpha(o2) and Galpha(q). Furthermore, glutamate uptake, mediated by vesicular glutamate transporters (VGLUTs), is decreased by the nonhydrolysable GTP-analog guanylylimidodiphosphate. Using mutant mice lacking various Galpha subunits, including Galpha(o1), Galpha(o2), Galpha(q), and Galpha11, and a Galpha(o2)-specific monoclonal antibody, we now show that VGLUTs are exclusively regulated by Galpha(o2). G-protein activation does not affect the electrochemical proton gradient serving as driving force for neurotransmitter uptake; rather, Galpha(o2) exerts its action by specifically affecting the chloride dependence of VGLUTs. All VGLUTs show maximal activity at approximately 5 mm chloride. Activated Galpha(o2) shifts this maximum to lower chloride concentrations. In contrast, glutamate uptake by vesicles isolated from Galpha(o2-/-) mice have completely lost chloride activation. Thus, Galpha(o2) acts on a putative regulatory chloride binding domain that appears to modulate transport activity of vesicular glutamate transporters.
Collapse
Affiliation(s)
- Sandra Winter
- AG Funktionelle Zellbiologie, Centrum für Anatomie, Charité Universitätsmedizin Berlin, D-10115 Berlin, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Bole DG, Ueda T. Inhibition of Vesicular Glutamate Uptake by Rose Bengal-Related Compounds: Structure–Activity Relationship. Neurochem Res 2005; 30:363-9. [PMID: 16018580 DOI: 10.1007/s11064-005-2610-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Synaptic vesicular accumulation of glutamate is a vital initial step in glutamate transmission. We have previously shown that Rose Bengal, a polyhalogenated fluorescein analog, is a potent inhibitor of glutamate uptake into synaptic vesicles. Here, we report the structural features of Rose Bengal required for this inhibition. Various Rose Bengal-related compounds, with systematic structural variations, were tested. Results indicate that the four iodo groups and the phenyl group attached to the xanthene moiety are critical for potent inhibitory activity. Replacement of these groups with two iodo groups and an alkyl group, respectively, results in substantial reduction in potency. Of further interest in creating high potency is the critical nature of the oxygen atom which links the two benzene rings of xanthene. Thus, the phenyl group and multiple iodo groups, as well as the bridging oxygen of xanthene, are crucial elements of Rose Bengal required for its potent inhibitory action.
Collapse
Affiliation(s)
- David G Bole
- Mental Health Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109-0669, USA
| | | |
Collapse
|
20
|
Porciúncula LO, Emanuelli T, Tavares RG, Schwarzbold C, Frizzo MES, Souza DO, Wajner M. Glutaric acid stimulates glutamate binding and astrocytic uptake and inhibits vesicular glutamate uptake in forebrain from young rats. Neurochem Int 2004; 45:1075-86. [PMID: 15337307 DOI: 10.1016/j.neuint.2004.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2003] [Revised: 04/23/2004] [Accepted: 05/03/2004] [Indexed: 11/16/2022]
Abstract
Glutaric acidemia type I (GA I) is an inherited neurometabolic disorder caused by glutaryl-CoA dehydrogenase deficiency, which leads to accumulation in body fluids and in brain of predominantly glutaric acid (GA), and to a lesser extent of 3-hydroxyglutaric and glutaconic acids. Neurological presentation is common in patients with GA I. Although the mechanisms underlying brain damage in this disorder are not yet well established, there is growing evidence that excitotoxicity may play a central role in the neuropathogenesis of this disease. In the present study, preparations of synaptosomes, synaptic plasma membranes and synaptic vesicles, as well as cultured astrocytes from rat forebrain were exposed to various concentrations of GA for the determination of the basal and potassium-induced release of [(3)H]glutamate by synaptosomes, Na(+)-independent glutamate binding to synaptic membranes and vesicular glutamate uptake and Na(+)-dependent glutamate uptake into astrocytes, respectively. GA (1-100 nM) significantly stimulated [(3)H]glutamate binding to brain plasma membranes (40-70%) in the absence of extracellular Na(+) concentrations, reflecting glutamate binding to receptors. Furthermore, this stimulatory effect was totally abolished by the metabotropic glutamate ligands DHPG, DCG-IV and l-AP4, attenuated by the ionotropic non-NMDA glutamate receptor agonist AMPA and had no interference of the NMDA receptor antagonist MK-801. Moreover, [(3)H]glutamate uptake into synaptic vesicles was inhibited by approximately 50% by 10 and 100 nM GA and Na(+)-dependent [(3)H]glutamate uptake by astrocytes was significantly increased (up to 50%) in a dose-dependent manner (maximal stimulation at 100 microM GA). In contrast, synaptosomal glutamate release was not affected by the acid at concentrations as high as 1 mM. These results indicate that the inhibition of glutamate uptake into synaptic vesicles by low concentrations GA may result in elevated concentrations of the excitatory neurotransmitter in the cytosol and the stimulatory effect of this organic acid on glutamate binding may potentially cause excitotoxicity to neural cells. Finally, taken together these results and previous findings showing that GA markedly decreases synaptosomal glutamate uptake, it is possible that the stimulatory effect of GA on astrocyte glutamate uptake might indicate that astrocytes may protect neurons from excitotoxic damage caused by GA by increasing glutamate uptake and therefore reducing the concentration of this excitatory neurotransmitter in the synaptic cleft.
Collapse
Affiliation(s)
- Lisiane O Porciúncula
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003 Porto Alegre, RS, Brazil
| | | | | | | | | | | | | |
Collapse
|
21
|
Abstract
PURPOSE OF REVIEW Primary Sjögren syndrome is an autoimmune disorder characterized by lymphocytic infiltrates and destruction of the salivary and lacrimal glands, and systemic production of autoantibodies to the ribonucleoprotein particles SS-A/Ro and SS-B/La. The purpose of this review is to discuss recent advances in the pathogenesis of primary Sjögren syndrome. RECENT FINDINGS Although several candidate autoantigens including alpha-fodrin have been reported in Sjögren syndrome, the pathogenic roles of the autoantigens in initiation and progression of SS are still unclear. It is possible that individual T cells activated by an appropriate self antigen can proliferate and form a restricted clone. Recent evidence suggests that the apoptotic pathway plays a central role in tolerizing T cells to tissue-specific self antigen, and may drive the autoimmune phenomenon. Cleavage of certain autoantigens during apoptosis may reveal immunocryptic epitopes that could potentially induce autoimmune response. The studies reviewed imply that Fas-mediated cytotoxicity and caspase-mediated alpha-fodrin proteolysis are involved in the progression of tissue destruction in Sjögren syndrome. Fas ligand (FasL), and its receptor Fas are essential in the homeostasis of the peripheral immune system. It can be considered that a defect in activation-induced cell death of effector T cells may result in the development of autoimmune exocrinopathy in Sjögren syndrome. SUMMARY Although the mechanisms by which estrogen deficiency influences autoimmune lesions remain unclear, it is possible that antiestrogenic actions might be a potent factor in the formation of pathogenic autoantigens.
Collapse
Affiliation(s)
- Yoshio Hayashi
- Department of Pathology, Tokushima University School of Dentistry, Tokushima, Japan.
| | | | | |
Collapse
|
22
|
Héja L, Kovács I, Szárics E, Incze M, Temesváriné-Major E, Dörnyei G, Peredy-Kajtár M, Gács-Baitz E, Szántay C, Kardos J. Novel Secoergoline Derivatives Inhibit Both GABA and Glutamate Uptake in Rat Brain Homogenates: Synthesis, in Vitro Pharmacology, and Modeling. J Med Chem 2004; 47:5620-9. [PMID: 15509161 DOI: 10.1021/jm040809c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three of twelve secoergoline derivatives (Z ethyl 4-[(ethoxycarbonylmethyl)methylamino]-2-methyl-3-phenylpent-2-enoate, 8; ethyl 1,6-dimethyl-3-oxo-5-phenyl-1,2,3,6-tetrahydropyridine-2-carboxylate, 9; Z methyl 4-[(methoxycarbonylmethyl)methylamino)-2-methyl-3-phenylpent-2-enoate, 11), containing bioisosteric sequences of GABA and Glu, inhibited both GABA and Glu transport through cerebrocortical membranes specifically. Compounds 8, 9, and 11 appeared to be equipotent inhibitors of GABA and Glu transport with IC50 values between 270 and 1100 microM, whereas derivatives 1-7, 10, and 12 were without effects. In the presence of GABA and Glu transport-specific nontransportable inhibitors, inhibition of GABA and Glu transport by 8, 9, and 11 proceeded in two phases. The two phases of inhibition were characterized by IC50 values between 4 and 180 nM and 360-1020 microM and different selectivity sequences. These findings may indicate the existence of some mechanism possibly mediated by a previously unrecognized GABA-Glu transporter. Derivatives with the cis, but not the trans configuration of bulky ester groups (8 vs 7 and 11 vs 12) showed significant inhibitory effect (IC50 values of 270 microM vs >>1000 microM and 1100 microM vs >>1000 microM on GABA transport, respectively). The cis-trans selectivity can be explained by docking these secoergolines in a three-dimensional model of the second and third transmembrane helices of GABA transporter type 1.
Collapse
Affiliation(s)
- László Héja
- Department of Neurochemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1025 Pusztaszeri út 59-67, Organic Chemistry Institute, Budapest University of Technology and Economics, H-1111 Gellért tér 4, Budapest, Hungary
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Shigeri Y, Seal RP, Shimamoto K. Molecular pharmacology of glutamate transporters, EAATs and VGLUTs. ACTA ACUST UNITED AC 2004; 45:250-65. [PMID: 15210307 DOI: 10.1016/j.brainresrev.2004.04.004] [Citation(s) in RCA: 247] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2004] [Indexed: 12/30/2022]
Abstract
L-Glutamate serves as a major excitatory neurotransmitter in the mammalian central nervous system (CNS) and is stored in synaptic vesicles by an uptake system that is dependent on the proton electrochemical gradient (VGLUTs). Following its exocytotic release, glutamate activates fast-acting, excitatory ionotropic receptors and slower-acting metabotropic receptors to mediate neurotransmission. Na+-dependent glutamate transporters (EAATs) located on the plasma membrane of neurons and glial cells rapidly terminate the action of glutamate and maintain its extracellular concentration below excitotoxic levels. Thus far, five Na+-dependent glutamate transporters (EAATs 1-5) and three vesicular glutamate transporters (VGLUTs 1-3) have been identified. Examination of EAATs and VGLUTs in brain preparations and by heterologous expression of the various cloned subtypes shows these two transporter families differ in many of their functional properties including substrate specificity and ion requirements. Alterations in the function and/or expression of these carriers have been implicated in a range of psychiatric and neurological disorders. EAATs have been implicated in cerebral stroke, epilepsy, Alzheimer's disease, HIV-associated dementia, Huntington's disease, amyotrophic lateral sclerosis (ALS) and malignant glioma, while VGLUTs have been implicated in schizophrenia. To examine the physiological role of glutamate transporters in more detail, several classes of transportable and non-transportable inhibitors have been developed, many of which are derivatives of the natural amino acids, aspartate and glutamate. This review summarizes the development of these indispensable pharmacological tools, which have been critical to our understanding of normal and abnormal synaptic transmission.
Collapse
Affiliation(s)
- Yasushi Shigeri
- National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan.
| | | | | |
Collapse
|
24
|
Ahnert-Hilger G, Höltje M, Pahner I, Winter S, Brunk I. Regulation of vesicular neurotransmitter transporters. Rev Physiol Biochem Pharmacol 2004; 150:140-60. [PMID: 14517724 DOI: 10.1007/s10254-003-0020-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurotransmitters are key molecules of neurotransmission. They are concentrated first in the cytosol and then in small synaptic vesicles of presynaptic terminals by the activity of specific neurotransmitter transporters of the plasma and the vesicular membrane, respectively. It has been shown that postsynaptic responses to single neurotransmitter packets vary over a wide range, which may be due to a regulation of vesicular neurotransmitter filling. Vesicular filling depends on the availability of transmitter molecules in the cytoplasm and the active transport into secretory vesicles relying on a proton gradient. In addition, it is modulated by vesicle-associated heterotrimeric G proteins, Galphao2 and Galphaq, which regulate VMAT activities in brain and platelets, respectively, and may also be involved in the regulation of VGLUTs. It appears that the vesicular content activates the G protein, suggesting a signal transduction form the luminal site which might be mediated by a vesicular G-protein coupled receptor or, as an alternative, possibly by the transporter itself. These novel functions of G proteins in the control of transmitter storage may link regulation of the vesicular content to intracellular signal cascades.
Collapse
Affiliation(s)
- G Ahnert-Hilger
- Institut für Anatomie und Neurowissenschaftliches Zentrum der Charité, Humboldt-Universität zu Berlin, Philippstr. 12, 10115 Berlin, Germany.
| | | | | | | | | |
Collapse
|
25
|
Abstract
Over the past decade, numerous advances have been made in relation to dry eye diagnostic markers, technologies, and treatment options. The mainstay of treatment of dry eye is the use of artificial tear solutions and punctum plugs. A goal is the development of agents that provide symptomatic treatment and, at the same time, improve ocular surface keratinization. It is the authors' opinion that the functional visual acuity tester and the new tear stability analysis system will be widely used to improve diagnosis and evaluate treatment outcomes in KCS. Advances in treatment will utilize anti-inflammatory agents, immune suppressants such as Cyclosporin A and FK-506, growth hormones, androgens, topical mucins and ocular surface stimulating drugs, like INS365. Although aqueous-deficient dry eye is most commonly not associated with Sjogren syndrome (SS), aqueous-deficient dry eye is often most severe in patients with SS; thus, this article focuses mainly on SS-associated dry eye.
Collapse
Affiliation(s)
- Murat Dogru
- Department of Ophthalmology, Tokyo Dental College, Ichikawa General Hospital, Tokyo, Japan
| | | |
Collapse
|
26
|
Reimer RJ, Edwards RH. Organic anion transport is the primary function of the SLC17/type I phosphate transporter family. Pflugers Arch 2004; 447:629-35. [PMID: 12811560 DOI: 10.1007/s00424-003-1087-y] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2003] [Accepted: 03/28/2003] [Indexed: 12/24/2022]
Abstract
Recently, molecular studies have determined that the SLC17/type I phosphate transporters, a family of proteins initially characterized as phosphate carriers, mediate the transport of organic anions. While their role in phosphate transport remains uncertain, it is now clear that the transport of organic anions facilitated by this family of proteins is involved in diverse processes ranging from the vesicular storage of the neurotransmitter glutamate to the degradation and metabolism of glycoproteins.
Collapse
Affiliation(s)
- Richard J Reimer
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, CA 94305, Stanford, USA,
| | | |
Collapse
|
27
|
Shigeri Y, Shimamoto K. [Pharmacology of excitatory amino acid transporters (EAATs and VGLUTs)]. Nihon Yakurigaku Zasshi 2003; 122:253-64. [PMID: 12939543 DOI: 10.1254/fpj.122.253] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
L-Glutamate is a major excitatory neurotransmitter in the mammalian central nervous system (CNS). It contributes not only to fast synaptic neurotransmission but also to complex physiological processes like plasticity, learning, and memory. Glutamate is synthesized in the cytoplasm and stored in synaptic vesicles by a proton gradient-dependent uptake system (VGLUTs). Following its exocytotic release, glutamate activates different kinds of glutamate receptors and mediates excitatory neurotransmission. To terminate the action of glutamate and maintain its extracellular concentration below excitotoxic levels, glutamate is quickly removed by Na(+)-dependent glutamate transporters (EAATs). Recently, three vesicular glutamate transporters (VGLUT1-3) and five Na(+)-dependent glutamate transporters (EAAT1-5) were identified. VGLUTs and EAATs are thought to play important roles in neuronal disorders, such as amyotrophic lateral sclerosis, Alzheimer's disease, cerebral ischemia, and Huntington's disease. In this review, the development of new compounds to regulate the function of VGLUTs and EAATs will be described.
Collapse
Affiliation(s)
- Yasushi Shigeri
- National Institute of Advanced Industrial Science and Technology, Ikeda, Osaka, Japan.
| | | |
Collapse
|
28
|
Ikemoto A, Bole DG, Ueda T. Glycolysis and glutamate accumulation into synaptic vesicles. Role of glyceraldehyde phosphate dehydrogenase and 3-phosphoglycerate kinase. J Biol Chem 2003; 278:5929-40. [PMID: 12488440 DOI: 10.1074/jbc.m211617200] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glucose is the major source of brain energy and is essential for maintaining normal brain and neuronal function. Hypoglycemia causes impaired synaptic transmission. This occurs even before significant reduction in global cellular ATP concentration, and relationships among glycolysis, ATP supply, and synaptic transmission are not well understood. We demonstrate that the glycolytic enzymes glyceraldehyde phosphate dehydrogenase (GAPDH) and 3-phosphoglycerate kinase (3-PGK) are enriched in synaptic vesicles, forming a functional complex, and that synaptic vesicles are capable of accumulating the excitatory neurotransmitter glutamate by harnessing ATP produced by vesicle-bound GAPDH/3-PGK at the expense of their substrates. The GAPDH inhibitor iodoacetate suppressed GAPDH/3-PGK-dependent, but not exogenous ATP-dependent, [(3)H]glutamate uptake into isolated synaptic vesicles. It also decreased vesicular [(3)H]glutamate content in the nerve ending preparation synaptosome; this decrease was reflected in reduction of depolarization-induced [(3)H]glutamate release. In contrast, oligomycin, a mitochondrial ATP synthase inhibitor, had minimal effect on any of these parameters. ADP at concentrations above 0.1 mm inhibited vesicular glutamate and dissipated membrane potential. This suggests that the coupled GAPDH/3-PGK system, which converts ADP to ATP, ensures maximal glutamate accumulation into presynaptic vesicles. Together, these observations provide insight into the essential nature of glycolysis in sustaining normal synaptic transmission.
Collapse
Affiliation(s)
- Atsushi Ikemoto
- Mental Health Research Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109-0669, USA
| | | | | |
Collapse
|
29
|
Amano T, Matsubayashi H, Ozkan ED, Sasa M, Serikawa T, Ueda T. Aberrant reduction of an inhibitory protein factor in a rat epileptic model. Epilepsy Res 2002; 51:81-91. [PMID: 12350384 DOI: 10.1016/s0920-1211(02)00122-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Certain forms of seizure involve excessive glutamate transmission. We have recently identified a protein, referred to as the inhibitory protein factor (IPF), which potently inhibits glutamate uptake into isolated synaptic vesicles. In an effort to understand the mechanism underlying excessive glutamate transmission associated with seizure, we have analyzed IPF content in various brain regions of the spontaneously epileptic rat, SER (tm/tm, zi/zi), the absence-seizure tremor rat, TM (tm/tm), and the seizure-free control rats zitter ZI (zi/zi) and Wistar tremor control, each at 13 weeks of age. IPF content was found to be markedly reduced in the hippocampus, but not in the other brain regions, of SER, compared to the control and TM rats. TM rats also exhibited reduced IPF content compared to seizure-free controls. These changes appear developmentally regulated; no such alteration was observed in 8-week-old rats, which rarely show seizure. These observations indicate that an aberrant decrease in IPF is associated with certain forms of seizure; this decrease could lead to an abnormal increase in the amount of exocytotically released glutamate through its excessive accumulation in synaptic vesicles.
Collapse
Affiliation(s)
- Taku Amano
- Mental Health Research Institute, Medical School, The University of Michigan, Ann Arbor, MI 48109-0669, USA
| | | | | | | | | | | |
Collapse
|
30
|
Saegusa K, Ishimaru N, Yanagi K, Mishima K, Arakaki R, Suda T, Saito I, Hayashi Y. Prevention and induction of autoimmune exocrinopathy is dependent on pathogenic autoantigen cleavage in murine Sjögren's syndrome. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:1050-7. [PMID: 12097413 DOI: 10.4049/jimmunol.169.2.1050] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The in vivo role of autoantigen cleavage during apoptosis in autoimmune diseases remains unclear. Previously, we found a cleavage product of 120-kDa alpha-fodrin as an important autoantigen in the pathogenesis of primary Sjögren's syndrome (SS). In the murine primary SS model, tissue-infiltrating CD4(+) T cells purified from the salivary glands bear a large proportion of Fas ligand, and the salivary gland duct cells constitutively possess Fas. Infiltrating CD4(+) T cells, but not CD8(+) T cells, identified significant (51)Cr release against mouse salivary gland cells. In vitro studies demonstrated that apoptotic mouse salivary gland cells result in a specific alpha-fodrin cleavage into 120 kDa and that preincubation with caspase inhibitor peptides blocked alpha-fodrin cleavage. In vivo treatment with caspase inhibitors N-benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone and N-acetyl-Asp-Glu-Val-Asp-al-CHO into the murine model results in dramatic inhibitory effects on the development of autoimmune lesions and in restoration of sicca syndrome. Furthermore, we found that immunization with recombinant alpha-fodrin protein identical with an autoantigen into normal recipients induced autoimmune lesions similar to SS. These data indicate that prevention and induction of autoimmune exocrinopathy is dependent on autoantigen cleavage via caspase cascade and that caspase inhibitors might provide a new therapeutic option directed at reducing tissue damage in the murine model for SS.
Collapse
Affiliation(s)
- Kaoru Saegusa
- Department of Pathology, Tokushima University School of Dentistry, Tokushima, Japan
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Bole DG, Hirata K, Ueda T. Prolonged depolarization of rat cerebral synaptosomes leads to an increase in vesicular glutamate content. Neurosci Lett 2002; 322:17-20. [PMID: 11958833 DOI: 10.1016/s0304-3940(02)00105-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Glutamate accumulation into synaptic vesicles is a vital step in glutamate synaptic transmission. In this study, we have explored the possibility that vesicular glutamate storage may be subject to some regulation. Synaptosomes were depolarized and subjected to [3H] glutamate under non-depolarizing conditions, and vesicular [3H] glutamate content was determined by a filter-based assay. We present evidence here that prolonged depolarization of synaptosomes leads to an increase in vesicular glutamate content. Induction of this enhanced state is time- and temperature-dependent. The enhanced state has two components, one readily reversible and the other long-lasting. The up-regulation of glutamate storage capacity could lead to an increase in quantal size and play a role in modulation of glutamate transmission efficiency.
Collapse
Affiliation(s)
- David G Bole
- Mental Health Research Institute, University of Michigan Medical School, 205 Zina Pitcher Place, Ann Arbor, MI 48109-0720, USA
| | | | | |
Collapse
|
32
|
Tamura Y, Ozkan ED, Bole DG, Ueda T. IPF, a vesicular uptake inhibitory protein factor, can reduce the Ca(2+)-dependent, evoked release of glutamate, GABA and serotonin. J Neurochem 2001; 76:1153-64. [PMID: 11181835 DOI: 10.1046/j.1471-4159.2001.00120.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Synaptic vesicles in the nerve terminal play a pivotal role in neurotransmission. Neurotransmitter accumulation into synaptic vesicles is catalyzed by distinct vesicular transporters, harnessing an electrochemical proton gradient generated by V-type proton-pump ATPase. However, little is known about regulation of the transmitter pool size, particularly in regard to amino acid neurotransmitters. We previously provided evidence for the existence of a potent endogenous inhibitory protein factor (IPF), which causes reduction of glutamate and GABA accumulation into isolated, purified synaptic vesicles. In this study we demonstrate that IPF is concentrated most in the synaptosomal cytosol fraction and that, when introduced into the synaptosome, it leads to a decrease in calcium-dependent exocytotic (but not calcium-independent) release of glutamate in a concentration-dependent manner. In contrast, alpha-fodrin (non-erythroid spectrin), which is structurally related to IPF and thought to serve as the precursor for IPF, is devoid of such inhibitory activity. Intrasynaptosomal IPF also caused reduction in exocytotic release of GABA and the monoamine neurotransmitter serotonin. Whether IPF affects vesicular storage of multiple neurotransmitters in vivo would depend upon the localization of IPF. These results raise the possibility that IPF may modulate synaptic transmission by acting as a quantal size regulator of one or more neurotransmitters.
Collapse
Affiliation(s)
- Y Tamura
- Mental Health Research Institute, The University of Michigan, Ann Arbor, Michigan, USA
| | | | | | | |
Collapse
|
33
|
Fonnum F, Fykse EM, Roseth S. Uptake of glutamate into synaptic vesicles. PROGRESS IN BRAIN RESEARCH 1999; 116:87-101. [PMID: 9932372 DOI: 10.1016/s0079-6123(08)60432-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- F Fonnum
- Norwegian Defence Research Establishment, Division for Environmental Toxicology, Kjeller, Norway.
| | | | | |
Collapse
|
34
|
Reimer RJ, Fon EA, Edwards RH. Vesicular neurotransmitter transport and the presynaptic regulation of quantal size. Curr Opin Neurobiol 1998; 8:405-12. [PMID: 9687352 DOI: 10.1016/s0959-4388(98)80068-8] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Specific transport activities package classical neurotransmitters into secretory vesicles for release by regulated exocytosis, but the proteins responsible for the vesicular transport of neurotransmitters are still being identified. One family of proteins includes vesicular transporters for monoamines and acetylcholine. Genetic manipulation in cells and in mice now shows that changes in the expression of these proteins can alter the amount of neurotransmitter stored per synaptic vesicle, the amount released and behavior. Although the mechanisms responsible for regulating these transporters in vivo remains unknown, recent work has demonstrated the potential for regulation by changes in intrinsic activity and in location. In addition, a recently identified vesicular transporter for GABA defines a novel family of proteins that mediates the packaging of amino acid neurotransmitters.
Collapse
Affiliation(s)
- R J Reimer
- Department of Neurology, UCSF School of Medicine 94143-0435, USA
| | | | | |
Collapse
|
35
|
Ozkan ED, Ueda T. Glutamate transport and storage in synaptic vesicles. JAPANESE JOURNAL OF PHARMACOLOGY 1998; 77:1-10. [PMID: 9639055 DOI: 10.1254/jjp.77.1] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Glutamate plays an important metabolic role in virtually every vertebrate cell. In particular, glutamate is the most common excitatory neurotransmitter in the vertebrate central nervous system. As such, the mechanism by which glutamate is diverted from its normal metabolic activities toward its role as a neurotransmitter has, in recent years, been systematically investigated. In glutamatergic nerve endings, synaptic vesicles accumulate and store a proportion of the cellular glutamate pool and, in response to appropriate signals, release glutamate into the synaptic cleft by exocytosis. Glutamate accumulation is accomplished by virtue of a glutamate uptake system present in the synaptic vesicle membrane. The uptake system consists of a transport protein, remarkably specific for glutamate, and a vacuolar-type H+-ATPase, which provides the coupling between ATP hydrolysis and glutamate transport. The precise manner in which the glutamate transporter and H+-ATPase operate is currently the subject of debate. Recent data relevant to this debate are reviewed in this article. Additionally, pharmacological agents thought to specifically interact with the vesicular glutamate transporter are discussed. Finally, a newly discovered, endogenous inhibitor of vesicular uptake, inhibitory protein factor (IPF), is discussed with some speculations as to its potential role as a presynaptic modulator of neurotransmission.
Collapse
Affiliation(s)
- E D Ozkan
- Mental Health Research Institute, Medical School, The University of Michigan, Ann Arbor 48109, USA
| | | |
Collapse
|
36
|
Thoidis G, Chen P, Pushkin AV, Vallega G, Leeman SE, Fine RE, Kandror KV. Two distinct populations of synaptic-like vesicles from rat brain. Proc Natl Acad Sci U S A 1998; 95:183-8. [PMID: 9419350 PMCID: PMC18168 DOI: 10.1073/pnas.95.1.183] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In nonneuronal cells, several plasma membrane proteins such as exofacial enzymes, receptors, and ion channels recycle between their intracellular compartment(s) and the cell surface via an endosomal pathway. In neurons, however, this pathway has not been extensively characterized. In particular, it remains unclear whether or not it is related to the recycling of small synaptic vesicles, the major pathway of membrane traffic in nerve terminals. To approach this problem, we purified and studied a vesicular fraction from rat brain synaptosomes. Two distinct populations of vesicles with different buoyant densities and sedimentation coefficients were detected in this fraction by sucrose gradient centrifugation and Western blot analysis of the individual proteins. Both populations contain proteins that are markers of synaptic vesicles, namely, SV2, synaptotagmin, synaptophysin, secretory carrier membrane proteins (SCAMPs), synaptobrevin, and rab3a. A striking difference between the two populations is the presence of arginine aminopeptidase activity (a previously suggested marker for the regulated endosomal recycling pathway) exclusively in the lighter less-dense vesicles. The same two vesicular populations were also detected in the preparation of clathrin-coated vesicles isolated from whole rat brain or purified synaptosomes after removal of their clathrin coats by incubation at pH 8.5. We conclude, therefore, that both types of vesicles recycle in synaptosomes via a clathrin-mediated pathway. These data present experimental evidence for biochemical heterogeneity of synaptic-like vesicles in rat brain.
Collapse
Affiliation(s)
- G Thoidis
- Department of Biochemistry, Boston University School of Medicine, 80 East Concord Street, Boston, MA 02118, USA
| | | | | | | | | | | | | |
Collapse
|