1
|
High-resolution micro-CT for 3D infarct characterization and segmentation in mice stroke models. Sci Rep 2022; 12:17471. [PMID: 36261475 PMCID: PMC9582034 DOI: 10.1038/s41598-022-21494-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 09/28/2022] [Indexed: 01/12/2023] Open
Abstract
Characterization of brain infarct lesions in rodent models of stroke is crucial to assess stroke pathophysiology and therapy outcome. Until recently, the analysis of brain lesions was performed using two techniques: (1) histological methods, such as TTC (Triphenyltetrazolium chloride), a time-consuming and inaccurate process; or (2) MRI imaging, a faster, 3D imaging method, that comes at a high cost. In the last decade, high-resolution micro-CT for 3D sample analysis turned into a simple, fast, and cheaper solution. Here, we successfully describe the application of brain contrasting agents (Osmium tetroxide and inorganic iodine) for high-resolution micro-CT imaging for fine location and quantification of ischemic lesion and edema in mouse preclinical stroke models. We used the intraluminal transient MCAO (Middle Cerebral Artery Occlusion) mouse stroke model to identify and quantify ischemic lesion and edema, and segment core and penumbra regions at different time points after ischemia, by manual and automatic methods. In the transient-ischemic-attack (TIA) mouse model, we can quantify striatal myelinated fibers degeneration. Of note, whole brain 3D reconstructions allow brain atlas co-registration, to identify the affected brain areas, and correlate them with functional impairment. This methodology proves to be a breakthrough in the field, by providing a precise and detailed assessment of stroke outcomes in preclinical animal studies.
Collapse
|
2
|
Pinto R, Magalhães A, Sousa M, Melo L, Lobo A, Barros P, Gomes JR. Bridging the Transient Intraluminal Stroke Preclinical Model to Clinical Practice: From Improved Surgical Procedures to a Workflow of Functional Tests. Front Neurol 2022; 13:846735. [PMID: 35359638 PMCID: PMC8963503 DOI: 10.3389/fneur.2022.846735] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/07/2022] [Indexed: 12/18/2022] Open
Abstract
Acute ischemic stroke (AIS) remains a leading cause of mortality, despite significant advances in therapy (endovascular thrombectomy). Failure in developing novel effective therapies is associated with unsuccessful translation from preclinical studies to clinical practice, associated to inconsistent and highly variable infarct areas and lack of relevant post-stroke functional evaluation in preclinical research. To outreach these limitations, we optimized the intraluminal transient middle cerebral occlusion, a widely used mouse stroke model, in two key parameters, selection of appropriate occlusion filaments and time of occlusion, which show a significant variation in the literature. We demonstrate that commercially available filaments with short coating length (1–2 mm), together with 45-min occlusion, results in a consistent affected brain region, similar to what is observed in most patients with AIS. Importantly, a dedicated post-stroke care protocol, based on clinical practice applied to patients who had stroke, resulted in lower mortality and improved mice welfare. Finally, a battery of tests covering relevant fine motor skills, sensory functions, and learning/memory behaviors revealed a significant effect of tMCAO brain infarction, which is parallel to patient symptomatology as measured by relevant clinical scales (NIH Stroke Scale, NIHSS and modified Rankin Scale, mRS). Thus, in order to enhance translation to clinical practice, future preclinical stroke research must consider the methodology described in this study, which includes improved reproducible surgical procedure, postoperative care, and the battery of functional tests. This will be a major step s closing the gap from bench to bedside, rendering the development of novel effective therapeutic approaches.
Collapse
Affiliation(s)
- Raquel Pinto
- Molecular Neurobiology Unit, IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Ana Magalhães
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Addiction Biology Unit, IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Mafalda Sousa
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Advanced Light Microscopy Unit, I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Lúcia Melo
- Molecular Neurobiology Unit, IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Andrea Lobo
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Addiction Biology Unit, IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Pedro Barros
- Neurology Department, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal.,Stroke Unit, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
| | - João R Gomes
- Molecular Neurobiology Unit, IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| |
Collapse
|
3
|
Systemic LPS-induced microglial activation results in increased GABAergic tone: A mechanism of protection against neuroinflammation in the medial prefrontal cortex in mice. Brain Behav Immun 2022; 99:53-69. [PMID: 34582995 DOI: 10.1016/j.bbi.2021.09.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 09/19/2021] [Accepted: 09/21/2021] [Indexed: 02/01/2023] Open
Abstract
Neuroinflammation with excess microglial activation and synaptic dysfunction are early symptoms of most neurological diseases. However, how microglia-associated neuroinflammation regulates synaptic activity remains obscure. We report here that acute neuroinflammation induced by intraperitoneal injection of lipopolysaccharide (LPS) results in cell-type-specific increases in inhibitory postsynaptic currents in the glutamatergic, but not the GABAergic, neurons of medial prefrontal cortex (mPFC), coinciding with excessive microglial activation. LPS causes upregulation in levels of GABAAR subunits, glutamine synthetase and vesicular GABA transporter, and downregulation in brain-derived neurotrophic factor (BDNF) and its receptor, pTrkB. Blockage of microglial activation by minocycline ameliorates LPS-induced abnormal expression of GABA signaling-related proteins and activity of synaptic and network. Moreover, minocycline prevents the mice from LPS-induced aberrant behavior, such as a reduction in total distance and time spent in the centre in the open field test; decreases in entries into the open arm of elevated-plus maze and in consumption of sucrose; increased immobility in the tail suspension test. Furthermore, upregulation of GABA signaling by tiagabine also prevents LPS-induced microglial activation and aberrant behavior. This study illustrates a mode of bidirectional constitutive signaling between the neural and immune compartments of the brain, and suggests that the mPFC is an important area for brain-immune system communication. Moreover, the present study highlights GABAergic signaling as a key therapeutic target for mitigating neuroinflammation-induced abnormal synaptic activity in the mPFC, together with the associated behavioral abnormalities.
Collapse
|
4
|
Mele M, Vieira R, Correia B, De Luca P, Duarte FV, Pinheiro PS, Duarte CB. Transient incubation of cultured hippocampal neurons in the absence of magnesium induces rhythmic and synchronized epileptiform-like activity. Sci Rep 2021; 11:11374. [PMID: 34059735 PMCID: PMC8167095 DOI: 10.1038/s41598-021-90486-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 04/29/2021] [Indexed: 11/09/2022] Open
Abstract
Cell culture models are important tools to study epileptogenesis mechanisms. The aim of this work was to characterize the spontaneous and synchronized rhythmic activity developed by cultured hippocampal neurons after transient incubation in zero Mg2+ to model Status Epilepticus. Cultured hippocampal neurons were transiently incubated with a Mg2+-free solution and the activity of neuronal networks was evaluated using single cell calcium imaging and whole-cell current clamp recordings. Here we report the development of synchronized and spontaneous [Ca2+]i transients in cultured hippocampal neurons immediately after transient incubation in a Mg2+-free solution. Spontaneous and synchronous [Ca2+]i oscillations were observed when the cells were then incubated in the presence of Mg2+. Functional studies also showed that transient incubation in Mg2+-free medium induces neuronal rhythmic burst activity that was prevented by antagonists of glutamate receptors. In conclusion, we report the development of epileptiform-like activity, characterized by spontaneous and synchronized discharges, in cultured hippocampal neurons transiently incubated in the absence of Mg2+. This model will allow studying synaptic alterations contributing to the hyperexcitability that underlies the development of seizures and will be useful in pharmacological studies for testing new drugs for the treatment of epilepsy.
Collapse
Affiliation(s)
- Miranda Mele
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.,Institute for Interdisciplinary Research, Coimbra, Portugal
| | - Ricardo Vieira
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal
| | - Bárbara Correia
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal
| | - Pasqualino De Luca
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.,Institute for Interdisciplinary Research, Coimbra, Portugal
| | - Filipe V Duarte
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.,Institute for Interdisciplinary Research, Coimbra, Portugal
| | - Paulo S Pinheiro
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.,Institute for Interdisciplinary Research, Coimbra, Portugal
| | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal. .,Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
| |
Collapse
|
5
|
Portugal CC, da Encarnação TG, Sagrillo MA, Pereira MR, Relvas JB, Socodato R, Paes-de-Carvalho R. Activation of adenosine A3 receptors regulates vitamin C transport and redox balance in neurons. Free Radic Biol Med 2021; 163:43-55. [PMID: 33307167 DOI: 10.1016/j.freeradbiomed.2020.11.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 11/01/2020] [Accepted: 11/30/2020] [Indexed: 12/19/2022]
Abstract
Adenosine is an important neuromodulator in the CNS, regulating neuronal survival and synaptic transmission. The antioxidant ascorbate (the reduced form of vitamin C) is concentrated in CNS neurons through a sodium-dependent transporter named SVCT2 and participates in several CNS processes, for instance, the regulation of glutamate receptors functioning and the synthesis of neuromodulators. Here we studied the interplay between the adenosinergic system and ascorbate transport in neurons. We found that selective activation of A3, but not of A1 or A2a, adenosine receptors modulated ascorbate transport, decreasing intracellular ascorbate content. Förster resonance energy transfer (FRET) analyses showed that A3 receptors associate with the ascorbate transporter SVCT2, suggesting tight signaling compartmentalization between A3 receptors and SVCT2. The activation of A3 receptors increased ascorbate release in an SVCT2-dependent manner, which largely altered the neuronal redox status without interfering with cell death, glycolytic metabolism, and bioenergetics. Overall, by regulating vitamin C transport, the adenosinergic system (via activation of A3 receptors) can regulate ascorbate bioavailability and control the redox balance in neurons.
Collapse
Affiliation(s)
- Camila C Portugal
- Instituto de Investigação e Inovação em Saúde (i3S) and Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
| | | | - Mayara A Sagrillo
- Department of Neurobiology, Biology Institute, Fluminense Federal University, Niterói, Brazil
| | - Mariana R Pereira
- Program of Neurosciences, Fluminense Federal University, Niterói, Brazil; Department of Neurobiology, Biology Institute, Fluminense Federal University, Niterói, Brazil
| | - João B Relvas
- Instituto de Investigação e Inovação em Saúde (i3S) and Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Renato Socodato
- Instituto de Investigação e Inovação em Saúde (i3S) and Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - Roberto Paes-de-Carvalho
- Program of Neurosciences, Fluminense Federal University, Niterói, Brazil; Department of Neurobiology, Biology Institute, Fluminense Federal University, Niterói, Brazil.
| |
Collapse
|
6
|
Gomes JR, Lobo A, Nogueira R, Terceiro AF, Costelha S, Lopes IM, Magalhães A, Summavielle T, Saraiva MJ. Neuronal megalin mediates synaptic plasticity-a novel mechanism underlying intellectual disabilities in megalin gene pathologies. Brain Commun 2020; 2:fcaa135. [PMID: 33225275 PMCID: PMC7667529 DOI: 10.1093/braincomms/fcaa135] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/14/2020] [Accepted: 07/16/2020] [Indexed: 12/15/2022] Open
Abstract
Donnai-Barrow syndrome, a genetic disorder associated to LRP2 (low-density lipoprotein receptor 2/megalin) mutations, is characterized by unexplained neurological symptoms and intellectual deficits. Megalin is a multifunctional endocytic clearance cell-surface receptor, mostly described in epithelial cells. This receptor is also expressed in the CNS, mainly in neurons, being involved in neurite outgrowth and neuroprotective mechanisms. Yet, the mechanisms involved in the regulation of megalin in the CNS are poorly understood. Using transthyretin knockout mice, a megalin ligand, we found that transthyretin positively regulates neuronal megalin levels in different CNS areas, particularly in the hippocampus. Transthyretin is even able to rescue megalin downregulation in transthyretin knockout hippocampal neuronal cultures, in a positive feedback mechanism via megalin. Importantly, transthyretin activates a regulated intracellular proteolysis mechanism of neuronal megalin, producing an intracellular domain, which is translocated to the nucleus, unveiling megalin C-terminal as a potential transcription factor, able to regulate gene expression. We unveil that neuronal megalin reduction affects physiological neuronal activity, leading to decreased neurite number, length and branching, and increasing neuronal susceptibility to a toxic insult. Finally, we unravel a new unexpected role of megalin in synaptic plasticity, by promoting the formation and maturation of dendritic spines, and contributing for the establishment of active synapses, both in in vitro and in vivo hippocampal neurons. Moreover, these structural and synaptic roles of megalin impact on learning and memory mechanisms, since megalin heterozygous mice show hippocampal-related memory and learning deficits in several behaviour tests. Altogether, we unveil a complete novel role of megalin in the physiological neuronal activity, mainly in synaptic plasticity with impact in learning and memory. Importantly, we contribute to disclose the molecular mechanisms underlying the cognitive and intellectual disabilities related to megalin gene pathologies.
Collapse
Affiliation(s)
- João R Gomes
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - Andrea Lobo
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Renata Nogueira
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - Ana F Terceiro
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Susete Costelha
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - Igor M Lopes
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Ana Magalhães
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Teresa Summavielle
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Maria J Saraiva
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| |
Collapse
|
7
|
Phosphorylation of Serine 157 Protects the Rat Glycine Transporter GlyT2 from Calpain Cleavage. J Mol Neurosci 2020; 70:1216-1224. [PMID: 32172509 DOI: 10.1007/s12031-020-01529-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/03/2020] [Indexed: 11/25/2022]
Abstract
The N-terminal region of the rat glycine transporter 2 (rGlyT2, SLC6A5) is cleaved by calpain protease in vitro, which raises the question of its protection against calpain in vivo. Here, we used a phosphomimetic and orthogonal phosphoserine translation approach to investigate the possible role of phosphorylation in the protection of two calpain cleavage sites, M156/S157 and G164/T165, previously identified in the N-terminus region of the rat GlyT2. Replacement of serine 157 with phosphomimetic aspartate or with orthogonal phosphoserine blocked both calpain cleavage sites and caused an electrophoretic mobility shift of rGlyT2N fusion proteins. Both effects can be reversed by dephosphorylation, suggesting that phosphorylation might induce structural changes in the rGlyT2 N-terminus, preventing the accessibility of the M156/S157 and G164/T165 cleavage sites to calpain in vivo. In comparison with the wild type, the phosphomimetic mutation S157D increased the total immunoreactivity of the transporter expressed in neuroblastoma cells, suggesting that serine 157 phosphorylation or phosphorylation-regulated calpain cleavage might contribute to the turnover of the glycine transporter GlyT2.
Collapse
|
8
|
Gaidin SG, Turovskaya MV, Gavrish MS, Babaev AA, Mal'tseva VN, Blinova EV, Turovsky EA. The selective BDNF overexpression in neurons protects neuroglial networks against OGD and glutamate-induced excitotoxicity. Int J Neurosci 2019; 130:363-383. [PMID: 31694441 DOI: 10.1080/00207454.2019.1691205] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Objective: Cerebral ischemia is accompanied by damage and death of a significant number of neurons due to glutamate excitotoxicity with subsequent a global increase of cytosolic Ca2+ concentration ([Ca2+]i). This study aimed to investigate the neuroprotective action of BDNF overexpression in hippocampal neurons against injury under ischemia-like conditions (oxygen and glucose deprivation) and glutamate-induced excitotoxicity (GluTox).Methods: The overexpression of BDNF was reached by the transduction of cell cultures with the adeno-associated (AAV)-Syn-BDNF-EGFP virus construct. Neuroprotective effects were mediated by Ca2+-dependent BDNF release followed by activation of the neuroprotective signaling cascades and changes of the gene expression. Thus, BDNF overexpression modulates Ca2+ homeostasis in cells, preventing Ca2+ overload and initiation of apoptotic and necrotic processes.Results:Antiapoptotic effect of BDNF overexpression is mediated via activation of phosphoinositide-3-kinase (PI3K) pathway and changing the expression of PI3K, HIF-1, Src and an anti-inflammatory cytokine IL-10. On the contrary, the decrease of expression of proapoptotic proteins such as Jun, Mapk8, caspase-3 and an inflammatory cytokine IL-1β was observed. These changes of expression were accompanied by the decrease of quantity of IL-1β receptors and the level of TNFα in cells in control, as well as 24 h after OGD. Besides, BDNF overexpression changes the expression of GABA(B) receptors. Also, the expression of NMDA and AMPA receptor subunits was altered towards a change in the conductivity of the receptors for Ca2+.Conclusion: Thus, our results demonstrate that neuronal BDNF overexpression reveals complex neuroprotective effects on the neurons and astrocytes under OGD and GluTox via inhibition of Ca2+ responses and regulation of gene expression.
Collapse
Affiliation(s)
- S G Gaidin
- Institute of Cell Biophysics, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Russian Academy of Sciences, Pushchino, Russia
| | - M V Turovskaya
- Institute of Cell Biophysics, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Russian Academy of Sciences, Pushchino, Russia
| | - M S Gavrish
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - A A Babaev
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - V N Mal'tseva
- Institute of Cell Biophysics, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Russian Academy of Sciences, Pushchino, Russia
| | - E V Blinova
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia.,N. P. Ogarev Mordovia State University, Saransk, Russia
| | - E A Turovsky
- Institute of Cell Biophysics, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Russian Academy of Sciences, Pushchino, Russia
| |
Collapse
|
9
|
The Roles of GABA in Ischemia-Reperfusion Injury in the Central Nervous System and Peripheral Organs. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:4028394. [PMID: 31814874 PMCID: PMC6878816 DOI: 10.1155/2019/4028394] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/27/2019] [Accepted: 10/18/2019] [Indexed: 12/30/2022]
Abstract
Ischemia-reperfusion (I/R) injury is a common pathological process, which may lead to dysfunctions and failures of multiple organs. A flawless medical way of endogenous therapeutic target can illuminate accurate clinical applications. γ-Aminobutyric acid (GABA) has been known as a marker in I/R injury of the central nervous system (mainly in the brain) for a long time, and it may play a vital role in the occurrence of I/R injury. It has been observed that throughout cerebral I/R, levels, syntheses, releases, metabolisms, receptors, and transmissions of GABA undergo complex pathological variations. Scientists have investigated the GABAergic enhancers for attenuating cerebral I/R injury; however, discussions on existing problems and mechanisms of available drugs were seldom carried out so far. Therefore, this review would summarize the process of pathological variations in the GABA system under cerebral I/R injury and will cover corresponding probable issues and mechanisms in using GABA-related drugs to illuminate the concern about clinical illness for accurately preventing cerebral I/R injury. In addition, the study will summarize the increasing GABA signals that can prevent I/R injuries occurring in peripheral organs, and the roles of GABA were also discussed correspondingly.
Collapse
|
10
|
González MI. Calpain-dependent cleavage of GABAergic proteins during epileptogenesis. Epilepsy Res 2019; 157:106206. [PMID: 31585309 DOI: 10.1016/j.eplepsyres.2019.106206] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 08/31/2019] [Accepted: 09/14/2019] [Indexed: 12/18/2022]
Abstract
Epileptogenesis is the processes by which a normal brain transforms and becomes capable of generate spontaneous seizures. In acquired epilepsy, it is thought that epileptogenesis can be triggered by a brain injury but the understanding of the cellular or molecular changes unraveling is incomplete. In the CA1 region of hippocampus less GABAergic activity precede the appearance of spontaneous seizures and calpain overactivation has been detected after chemoconvulsant-induced status epilepticus (SE). Inhibition of calpain overactivation following SE ameliorates seizure burden, suggesting a role for calpain dysregulation in epileptogenesis. The current study analyzed if GABAergic proteins (i.e., gephyrin, the vesicular GABA transporter and the potassium chloride co-transporter 2) undergo calpain-dependent cleavage during epileptogenesis. A time-dependent generation of break down products (BDPs) for these proteins was observed in the CA1 region of hippocampus after pilocarpine-induced SE. Generation of these BDPs was partially blocked by treatment with the calpain inhibitor MDL-28170. These findings suggest that calpain-dependent loss of GABAergic proteins might promote the erosion of inhibitory drive and contribute to hyperexcitability during epileptogenesis.
Collapse
Affiliation(s)
- Marco I González
- Department of Pediatrics, Division of Neurology and Translational Epilepsy Research Program, University of Colorado School of Medicine, Aurora, CO, 80045, USA.
| |
Collapse
|
11
|
Gomes JR, Sárkány Z, Teixeira A, Nogueira R, Cabrito I, Soares H, Wittelsberger A, Stortelers C, Macedo-Ribeiro S, Vanlandschoot P, Saraiva MJ. Anti-TTR Nanobodies Allow the Identification of TTR Neuritogenic Epitope Associated with TTR-Megalin Neurotrophic Activities. ACS Chem Neurosci 2019; 10:704-715. [PMID: 30346709 DOI: 10.1021/acschemneuro.8b00502] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Transthyretin (TTR) has intrinsic neurotrophic physiological activities independent from its thyroxine ligands, which involve activation of signaling pathways through interaction with megalin. Still, the megalin binding motif on TTR is unknown. Nanobodies (Nb) have the ability to bind "hard to reach" epitopes being useful tools for protein/structure function. In this work, we characterize two anti-TTR Nanobodies, with similar mouse TTR binding affinities, although only one is able to block its neuritogenic activity (169F7_Nb). Through epitope mapping, we identified amino acids 14-18, at the entrance of the TTR central channel, to be important for interaction with megalin, and a stable TTR K15N mutant in that region was constructed. The TTR K15N mutant lacks neuritogenic activity, indicating that K15 is critical for TTR neuritogenic activity. Thus, we identify the putative binding site for megalin and describe two Nanobodies that will allow research and clarification of TTR physiological properties, regarding its neurotrophic effects.
Collapse
Affiliation(s)
- João R. Gomes
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | - Zsuzsa Sárkány
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Biomolecular Structure & Function, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | - Anabela Teixeira
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | - Renata Nogueira
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | | | | | | | | | - Sandra Macedo-Ribeiro
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Biomolecular Structure & Function, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | | | - Maria J. Saraiva
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| |
Collapse
|
12
|
Gomes JR, Cabrito I, Soares HR, Costelha S, Teixeira A, Wittelsberger A, Stortelers C, Vanlandschoot P, Saraiva MJ. Delivery of an anti-transthyretin Nanobody to the brain through intranasal administration reveals transthyretin expression and secretion by motor neurons. J Neurochem 2018. [PMID: 29527688 PMCID: PMC6001800 DOI: 10.1111/jnc.14332] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transthyretin (TTR) is a transport protein of retinol and thyroxine in serum and CSF, which is mainly secreted by liver and choroid plexus, and in smaller amounts in other cells throughout the body. The exact role of TTR and its specific expression in Central Nervous System (CNS) remains understudied. We investigated TTR expression and metabolism in CNS, through the intranasal and intracerebroventricular delivery of a specific anti-TTR Nanobody to the brain, unveiling Nanobody pharmacokinetics to the CNS. In TTR deficient mice, we observed that anti-TTR Nanobody was successfully distributed throughout all brain areas, and also reaching the spinal cord. In wild-type mice, a similar distribution pattern was observed. However, in areas known to be rich in TTR, reduced levels of Nanobody were found, suggesting potential target-mediated effects. Indeed, in wild-type mice, the anti-TTR Nanobody was specifically internalized in a receptor-mediated process, by neuronal-like cells, which were identified as motor neurons. Whereas in KO TTR mice Nanobody was internalized by all cells, for late lysosomal degradation. Moreover, we demonstrate that in vivo motor neurons also actively synthesize TTR. Finally, in vitro cultured primary motor neurons were also found to synthesize and secrete TTR into culture media. Thus, through a novel intranasal CNS distribution study with an anti-TTR Nanobody, we disclose a new cell type capable of synthesizing TTR, which might be important for the understanding of the physiological role of TTR, as well as in pathological conditions where TTR levels are altered in CSF, such as amyotrophic lateral sclerosis.
Collapse
Affiliation(s)
- João R Gomes
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | | | | | - Susete Costelha
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | - Anabela Teixeira
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | | | | | | | - Maria J Saraiva
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| |
Collapse
|
13
|
Bi G, Zhang Q, Zhang Y, Liang Y, Wang X, Li Y, Dong R, Liu Z, Qu H. Therapeutic effect of transmembrane TAT-tCNTF via Erk and Akt activation using in vitro and in vivo models of Alzheimer's disease. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2018; 11:1855-1865. [PMID: 31938292 PMCID: PMC6958197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 01/09/2018] [Indexed: 06/10/2023]
Abstract
Suppressing Alzheimer's disease (AD) progression via its pathological characteristics, namely senile plaques and neurofibrillary tangles, is an efficient treatment approach. Numerous studies have indicated that ciliary neurotrophic factor (CNTF) not only promotes neuronal growth and maintains cell survival but also significantly reduces amyloid beta (Aβ) aggregation and deposition. In this study, transactivator of transcription (TAT) was linked to truncated ciliary neurotrophic factor (tCNTF) and expressed as a fusion protein, TAT-tCNTF, to overcome the transmembrane inability of CNTF. Accordingly, TAT-tCNTF was shown to automatically transport across biomembranes and enter cells mainly by macropinocytosis. Furthermore, TAT-tCNTF increased cell viability in hippocampal neurons treated with Aβ. After intracerebroventricular Aβ injection, mice exhibited amyloid deposits, which were significantly reduced after intraperitoneal TAT-tCNTF injection. Indeed, TAT-tCNTF significantly reduced Aβ-induced tau hyperphosphorylation, and yet barely affected amyloid precursor protein. Accordingly, it was possible to elucidate its potential pharmacological mechanism, with the working effect of TAT-tCNTF shown to be performed by specifically binding to its receptor, CNTFRα, and then activating the Extracellular regulated protein kinases (Erk) and Protein kinase B/Akt pathways exclusive of the Signal transducers and activators of transcription 3 (Stat3) pathway.
Collapse
Affiliation(s)
- Guofang Bi
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Qin Zhang
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Yuanyuan Zhang
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Yuguang Liang
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Xiaofang Wang
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Yuanyuan Li
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Ruihua Dong
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Zeyuan Liu
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| | - Hengyan Qu
- Department of Clinical Pharmacology, Affiliated Hospital, Academy of Military Medical Sciences Beijing, P. R. China
| |
Collapse
|
14
|
Wang C, Xu B, Ma Z, Liu C, Deng Y, Liu W, Xu ZF. Inhibition of Calpains Protects Mn-Induced Neurotransmitter release disorders in Synaptosomes from Mice: Involvement of SNARE Complex and Synaptic Vesicle Fusion. Sci Rep 2017. [PMID: 28623313 PMCID: PMC5473846 DOI: 10.1038/s41598-017-04017-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Overexposure to manganese (Mn) could disrupt neurotransmitter release via influencing the formation of SNARE complex, but the underlying mechanisms are still unclear. A previous study demonstrated that SNAP-25 is one of substrate of calpains. The current study investigated whether calpains were involved in Mn-induced disorder of SNARE complex. After mice were treated with Mn for 24 days, Mn deposition increased significantly in basal nuclei in Mn-treated and calpeptin pre-treated groups. Behaviorally, less time spent in the center of the area and decreased average velocity significantly in an open field test after 24 days of Mn exposure. With the increase in MnCl2 dosage, intracellular Ca2+ increased significantly, but pretreatment with calpeptin caused a dose-dependent decrease in calpains activity. There were fragments of N-terminal of SNAP-25 protein appearance in Mn-treated groups, but it is decreased with pretreatment of calpeptin. FM1-43-labeled synaptic vesicles also provided evidence that the treatment with Mn resulted in increasing first and then decreasing, which was consistent with Glu release and the 80 kDa protein levels of SNARE complexes. In summary, Mn induced the disorder of neurotransmitter release through influencing the formation of SNARE complex via cleaving SNAP-25 by overactivation of calpains in vivo.
Collapse
Affiliation(s)
- Can Wang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, People's Republic of China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, People's Republic of China.
| | - Zhuo Ma
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, People's Republic of China
| | - Chang Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, People's Republic of China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, People's Republic of China
| | - Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, People's Republic of China
| | - Zhao-Fa Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, People's Republic of China
| |
Collapse
|
15
|
Transthyretin provides trophic support via megalin by promoting neurite outgrowth and neuroprotection in cerebral ischemia. Cell Death Differ 2016; 23:1749-1764. [PMID: 27518433 PMCID: PMC5071567 DOI: 10.1038/cdd.2016.64] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/03/2016] [Accepted: 06/08/2016] [Indexed: 02/06/2023] Open
Abstract
Transthyretin (TTR) is a protein whose function has been associated to binding and distribution of thyroid hormones in the body and brain. However, little is known regarding the downstream signaling pathways triggered by wild-type TTR in the CNS either in neuroprotection of cerebral ischemia or in physiological conditions. In this study, we investigated how TTR affects hippocampal neurons in physiologic/pathologic conditions. Recombinant TTR significantly boosted neurite outgrowth in mice hippocampal neurons, both in number and length, independently of its ligands. This TTR neuritogenic activity is mediated by the megalin receptor and is lost in megalin-deficient neurons. We also found that TTR activates the mitogen-activated protein kinase (MAPK) pathways (ERK1/2) and Akt through Src, leading to the phosphorylation of transcription factor CREB. In addition, TTR promoted a transient rise in intracellular calcium through NMDA receptors, in a Src/megalin-dependent manner. Moreover, under excitotoxic conditions, TTR stimulation rescued cell death and neurite loss in TTR KO hippocampal neurons, which are more sensitive to excitotoxic degeneration than WT neurons, in a megalin-dependent manner. CREB was also activated by TTR under excitotoxic conditions, contributing to changes in the balance between Bcl2 protein family members, toward anti-apoptotic proteins (Bcl2/BclXL versus Bax). Finally, we clarify that TTR KO mice subjected to pMCAO have larger infarcts than WT mice, because of TTR and megalin neuronal downregulation. Our results indicate that TTR might be regarded as a neurotrophic factor, because it stimulates neurite outgrowth under physiological conditions, and promotes neuroprotection in ischemic conditions.
Collapse
|
16
|
Curcio M, Salazar IL, Mele M, Canzoniero LMT, Duarte CB. Calpains and neuronal damage in the ischemic brain: The swiss knife in synaptic injury. Prog Neurobiol 2016; 143:1-35. [PMID: 27283248 DOI: 10.1016/j.pneurobio.2016.06.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 03/22/2016] [Accepted: 05/09/2016] [Indexed: 12/26/2022]
Abstract
The excessive extracellular accumulation of glutamate in the ischemic brain leads to an overactivation of glutamate receptors with consequent excitotoxic neuronal death. Neuronal demise is largely due to a sustained activation of NMDA receptors for glutamate, with a consequent increase in the intracellular Ca(2+) concentration and activation of calcium- dependent mechanisms. Calpains are a group of Ca(2+)-dependent proteases that truncate specific proteins, and some of the cleavage products remain in the cell, although with a distinct function. Numerous studies have shown pre- and post-synaptic effects of calpains on glutamatergic and GABAergic synapses, targeting membrane- associated proteins as well as intracellular proteins. The resulting changes in the presynaptic proteome alter neurotransmitter release, while the cleavage of postsynaptic proteins affects directly or indirectly the activity of neurotransmitter receptors and downstream mechanisms. These alterations also disturb the balance between excitatory and inhibitory neurotransmission in the brain, with an impact in neuronal demise. In this review we discuss the evidence pointing to a role for calpains in the dysregulation of excitatory and inhibitory synapses in brain ischemia, at the pre- and post-synaptic levels, as well as the functional consequences. Although targeting calpain-dependent mechanisms may constitute a good therapeutic approach for stroke, specific strategies should be developed to avoid non-specific effects given the important regulatory role played by these proteases under normal physiological conditions.
Collapse
Affiliation(s)
- Michele Curcio
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Ivan L Salazar
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Doctoral Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra (IIIUC), 3030-789 Coimbra, Portugal
| | - Miranda Mele
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | | | - Carlos B Duarte
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal.
| |
Collapse
|
17
|
Mele M, Aspromonte MC, Duarte CB. Downregulation of GABA A Receptor Recycling Mediated by HAP1 Contributes to Neuronal Death in In Vitro Brain Ischemia. Mol Neurobiol 2016; 54:45-57. [PMID: 26732589 DOI: 10.1007/s12035-015-9661-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 12/17/2015] [Indexed: 01/17/2023]
Abstract
Downregulation of GABAergic synaptic transmission contributes to the increase in overall excitatory activity in the ischemic brain. A reduction of GABAA receptor (GABAAR) surface expression partly accounts for this decrease in inhibitory activity, but the mechanisms involved are not fully elucidated. In this work, we investigated the alterations in GABAAR trafficking in cultured rat hippocampal neurons subjected to oxygen/glucose deprivation (OGD), an in vitro model of global brain ischemia, and their impact in neuronal death. The traffic of GABAAR was evaluated after transfection of hippocampal neurons with myc-tagged GABAAR β3 subunits. OGD decreased the rate of GABAAR β3 subunit recycling and reduced the interaction of the receptors with HAP1, a protein involved in the recycling of the receptors. Furthermore, OGD induced a calpain-mediated cleavage of HAP1. Transfection of hippocampal neurons with HAP1A or HAP1B isoforms reduced the OGD-induced decrease in surface expression of GABAAR β3 subunits, and HAP1A maintained the rate of receptor recycling. Furthermore, transfection of hippocampal neurons with HAP1 significantly decreased OGD-induced cell death. These results show a key role for HAP1 protein in the downmodulation of GABAergic neurotransmission during cerebral ischemia, which contributes to neuronal demise.
Collapse
Affiliation(s)
- Miranda Mele
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine (Polo I), University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.,Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Coimbra, 3030-789, Portugal
| | - Maria Cristina Aspromonte
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine (Polo I), University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal.,Department of Science and Technology, University of Sannio, Benevento, 82100, Italy
| | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, Faculty of Medicine (Polo I), University of Coimbra, Rua Larga, 3004-504, Coimbra, Portugal. .,Department of Life Sciences, University of Coimbra, Coimbra, 3001-401, Portugal.
| |
Collapse
|
18
|
Abstract
Objective: To analyze the mechanism of neuroprotection of insulin and which blood glucose range was benefit for insulin exerting neuroprotective action. Data Sources: The study is based on the data from PubMed. Study Selection: Articles were selected with the search terms “insulin”, “blood glucose”, “neuroprotection”, “brain”, “glycogen”, “cerebral ischemia”, “neuronal necrosis”, “glutamate”, “γ-aminobutyric acid”. Results: Insulin has neuroprotection. The mechanisms include the regulation of neurotransmitter, promoting glycogen synthesis, and inhibition of neuronal necrosis and apoptosis. Insulin could play its role in neuroprotection by avoiding hypoglycemia and hyperglycemia. Conclusions: Intermittent and long-term infusion insulin may be a benefit for patients with ischemic brain damage at blood glucose 6–9 mmol/L.
Collapse
Affiliation(s)
| | - Yu Pei
- Department of Endocrinology, Chinese PLA General Hospital, Beijing 100853, China
| |
Collapse
|
19
|
Costa JT, Mele M, Baptista MS, Gomes JR, Ruscher K, Nobre RJ, de Almeida LP, Wieloch T, Duarte CB. Gephyrin Cleavage in In Vitro Brain Ischemia Decreases GABAA Receptor Clustering and Contributes to Neuronal Death. Mol Neurobiol 2015; 53:3513-3527. [PMID: 26093381 DOI: 10.1007/s12035-015-9283-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 06/02/2015] [Indexed: 02/01/2023]
Abstract
GABA (γ-aminobutyric acid) is the major inhibitory neurotransmitter in the central nervous system, and changes in GABAergic neurotransmission modulate the activity of neuronal networks. Gephyrin is a scaffold protein responsible for the traffic and synaptic anchoring of GABAA receptors (GABAAR); therefore, changes in gephyrin expression and oligomerization may affect the activity of GABAergic synapses. In this work, we investigated the changes in gephyrin protein levels during brain ischemia and in excitotoxic conditions, which may affect synaptic clustering of GABAAR. We found that gephyrin is cleaved by calpains following excitotoxic stimulation of hippocampal neurons with glutamate, as well as after intrahippocampal injection of kainate, giving rise to a stable cleavage product. Gephyrin cleavage was also observed in cultured hippocampal neurons subjected to transient oxygen-glucose deprivation (OGD), an in vitro model of brain ischemia, and after transient middle cerebral artery occlusion (MCAO) in mice, a model of focal brain ischemia. Furthermore, a truncated form of gephyrin decreased the synaptic clustering of the protein, reduced the synaptic pool of GABAAR containing γ2 subunits and upregulated OGD-induced cell death in hippocampal cultures. Our results show that excitotoxicity and brain ischemia downregulate full-length gephyrin with a concomitant generation of truncated products, which affect synaptic clustering of GABAAR and cell death.
Collapse
Affiliation(s)
- João T Costa
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
| | - Miranda Mele
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Coimbra, 3030-789, Portugal
| | - Márcio S Baptista
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
| | - João R Gomes
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal
| | - Karsten Ruscher
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, S-22184, Lund, Sweden
| | - Rui J Nobre
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Coimbra, 3030-789, Portugal
| | - Luís Pereira de Almeida
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal.,Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Tadeusz Wieloch
- Laboratory for Experimental Brain Research, Division of Neurosurgery, Department of Clinical Sciences, Lund University, BMC A13, S-22184, Lund, Sweden
| | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504, Coimbra, Portugal. .,Department of Life Sciences, University of Coimbra, 3004-517, Coimbra, Portugal. .,Center for Neuroscience and Cell Biology, Faculty of Medicine, Polo I, Rua Larga, University of Coimbra, 3004-504, Coimbra, Portugal.
| |
Collapse
|
20
|
Vieira M, Gomes JR, Saraiva MJ. Transthyretin Induces Insulin-like Growth Factor I Nuclear Translocation Regulating Its Levels in the Hippocampus. Mol Neurobiol 2014; 51:1468-79. [PMID: 25084758 PMCID: PMC4434863 DOI: 10.1007/s12035-014-8824-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/17/2014] [Indexed: 01/02/2023]
Abstract
Transthyretin (TTR) is the carrier protein of thyroxine (T4) and binds to retinol-binding protein (RBP)-retinol complex. It is mainly synthesized by both liver and choroid plexuses of the brain. Besides these properties, it has a neuroprotective role in several contexts such as Alzheimer’s disease (AD) and cerebral ischemia. Activation of insulin-like growth factor receptor I (IGF-IR) pathways and increased levels of TTR are associated with absence of neurodegeneration in an AD mouse model. In the present study, we verified that young/adult TTR null mice had decreased levels of IGF-IR in the hippocampus, but not in choroid plexus when compared with wild-type age-matched controls. Moreover, we could also demonstrate that conditional silencing of peripheral TTR did not have any influence in hippocampal IGF-IR levels, indicating that TTR effect on IGF-IR levels is due to TTR mainly synthesized in the choroid plexus. In vitro cellular studies, using NIH3T3 cell line and primary cultured hippocampal neurons, we showed that TTR upregulates IGF-IR at the transcription and translation levels and that is dependent on receptor internalization. Using a GFP-IGF-IR fusion protein, we also found that TTR triggers IGF-IR nuclear translocation in cultured neurons. We could also see an enrichment of IGF-IR in the nuclear fraction, after TTR stimulation in NIH3T3 cells, indicating that IGF-IR regulation, triggered by TTR is induced by nuclear translocation. In summary, the results provide evidence of a new role of TTR as a transcription inducer of IGF-IR in central nervous system (CNS), unveiling a new role in neuroprotection.
Collapse
Affiliation(s)
- Marta Vieira
- Molecular Neurobiology Unit, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180, Porto, Portugal
| | | | | |
Collapse
|
21
|
Kaila K, Ruusuvuori E, Seja P, Voipio J, Puskarjov M. GABA actions and ionic plasticity in epilepsy. Curr Opin Neurobiol 2014; 26:34-41. [PMID: 24650502 DOI: 10.1016/j.conb.2013.11.004] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 10/23/2013] [Accepted: 11/06/2013] [Indexed: 11/18/2022]
Abstract
Concepts of epilepsy, based on a simple change in neuronal excitation/inhibition balance, have subsided in face of recent insights into the large diversity and context-dependence of signaling mechanisms at the molecular, cellular and neuronal network level. GABAergic transmission exerts both seizure-suppressing and seizure-promoting actions. These two roles are prone to short-term and long-term alterations, evident both during epileptogenesis and during individual epileptiform events. The driving force of GABAergic currents is controlled by ion-regulatory molecules such as the neuronal K-Cl cotransporter KCC2 and cytosolic carbonic anhydrases. Accumulating evidence suggests that neuronal ion regulation is highly plastic, thereby contributing to the multiple roles ascribed to GABAergic signaling during epileptogenesis and epilepsy.
Collapse
Affiliation(s)
- Kai Kaila
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland.
| | - Eva Ruusuvuori
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Patricia Seja
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Juha Voipio
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland
| | - Martin Puskarjov
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| |
Collapse
|
22
|
Xie W, Song YJ, Li D, Pan LP, Wu QJ, Tian X. The suppression of epileptiform discharges in cultured hippocampal neurons is regulated via alterations in full-length tropomyosin-related kinase type B receptors signalling activity. Eur J Neurosci 2014; 40:2564-75. [PMID: 24830751 DOI: 10.1111/ejn.12620] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 04/01/2014] [Accepted: 04/11/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Wei Xie
- School of Biomedical Engineering; Tianjin Medical University; Tianjin China
| | - Yi-Jun Song
- Department of Neurology; Tianjin Medical University General Hospital & Key Laboratory of Neurotrauma; Variation and Regeneration; Ministry of Education and Tianjin Municipal Government; Tianjin China
| | - Dai Li
- Senior Officials Inpatient Ward; Tianjin Medical University General Hospital and Tianjin Neurological Institute; Tianjin China
| | - Li-Ping Pan
- Department of Neurology; Tianjin Medical University General Hospital & Key Laboratory of Neurotrauma; Variation and Regeneration; Ministry of Education and Tianjin Municipal Government; Tianjin China
| | - Qiu-Jing Wu
- Department of Neurology; Tianjin Medical University General Hospital & Key Laboratory of Neurotrauma; Variation and Regeneration; Ministry of Education and Tianjin Municipal Government; Tianjin China
| | - Xin Tian
- School of Biomedical Engineering; Tianjin Medical University; Tianjin China
| |
Collapse
|
23
|
Mele M, Ribeiro L, Inácio AR, Wieloch T, Duarte CB. GABA(A) receptor dephosphorylation followed by internalization is coupled to neuronal death in in vitro ischemia. Neurobiol Dis 2014; 65:220-32. [PMID: 24513087 DOI: 10.1016/j.nbd.2014.01.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/08/2014] [Accepted: 01/30/2014] [Indexed: 12/22/2022] Open
Abstract
Cerebral ischemia is characterized by an early disruption of GABAergic neurotransmission contributing to an imbalance of the excitatory/inhibitory equilibrium and neuronal death, but the molecular mechanisms involved are not fully understood. Here we report a downregulation of GABA(A) receptor (GABA(A)R) expression, affecting both mRNA and protein levels of GABA(A)R subunits, in hippocampal neurons subjected to oxygen-glucose deprivation (OGD), an in vitro model of ischemia. Similar alterations in the abundance of GABA(A)R subunits were observed in in vivo brain ischemia. OGD reduced the interaction of surface GABA(A)R with the scaffold protein gephyrin, followed by clathrin-dependent receptor internalization. Internalization of GABA(A)R was dependent on glutamate receptor activation and mediated by dephosphorylation of the β3 subunit at serine 408/409. Expression of phospho-mimetic mutant GABA(A)R β3 subunits prevented receptor internalization and protected hippocampal neurons from ischemic cell death. The results show a key role for β3 GABA(A)R subunit dephosphorylation in the downregulation of GABAergic synaptic transmission in brain ischemia, contributing to neuronal death. GABA(A)R phosphorylation might be a therapeutic target to preserve synaptic inhibition in brain ischemia.
Collapse
Affiliation(s)
- Miranda Mele
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra (IIIUC), 3030-789 Coimbra, Portugal
| | - Luís Ribeiro
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Ana R Inácio
- Wallenberg Neuroscience Center, Lund University, 221 84 Lund, Sweden
| | - Tadeusz Wieloch
- Wallenberg Neuroscience Center, Lund University, 221 84 Lund, Sweden
| | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
| |
Collapse
|
24
|
Caldeira MV, Salazar IL, Curcio M, Canzoniero LMT, Duarte CB. Role of the ubiquitin-proteasome system in brain ischemia: friend or foe? Prog Neurobiol 2013; 112:50-69. [PMID: 24157661 DOI: 10.1016/j.pneurobio.2013.10.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 10/08/2013] [Accepted: 10/15/2013] [Indexed: 11/26/2022]
Abstract
The ubiquitin-proteasome system (UPS) is a catalytic machinery that targets numerous cellular proteins for degradation, thus being essential to control a wide range of basic cellular processes and cell survival. Degradation of intracellular proteins via the UPS is a tightly regulated process initiated by tagging a target protein with a specific ubiquitin chain. Neurons are particularly vulnerable to any change in protein composition, and therefore the UPS is a key regulator of neuronal physiology. Alterations in UPS activity may induce pathological responses, ultimately leading to neuronal cell death. Brain ischemia triggers a complex series of biochemical and molecular mechanisms, such as an inflammatory response, an exacerbated production of misfolded and oxidized proteins, due to oxidative stress, and the breakdown of cellular integrity mainly mediated by excitotoxic glutamatergic signaling. Brain ischemia also damages protein degradation pathways which, together with the overproduction of damaged proteins and consequent upregulation of ubiquitin-conjugated proteins, contribute to the accumulation of ubiquitin-containing proteinaceous deposits. Despite recent advances, the factors leading to deposition of such aggregates after cerebral ischemic injury remain poorly understood. This review discusses the current knowledge on the role of the UPS in brain function and the molecular mechanisms contributing to UPS dysfunction in brain ischemia with consequent accumulation of ubiquitin-containing proteins. Chemical inhibitors of the proteasome and small molecule inhibitors of deubiquitinating enzymes, which promote the degradation of proteins by the proteasome, were both shown to provide neuroprotection in brain ischemia, and this apparent contradiction is also discussed in this review.
Collapse
Affiliation(s)
- Margarida V Caldeira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Ivan L Salazar
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Doctoral Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra (IIIUC), Portugal
| | - Michele Curcio
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Science and Technology, University of Sannio, Benevento, Italy
| | | | - Carlos B Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, 3004-517 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
| |
Collapse
|
25
|
Sorting of the vesicular GABA transporter to functional vesicle pools by an atypical dileucine-like motif. J Neurosci 2013; 33:10634-46. [PMID: 23804087 DOI: 10.1523/jneurosci.0329-13.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Increasing evidence indicates that individual synaptic vesicle proteins may use different signals, endocytic adaptors, and trafficking pathways for sorting to distinct pools of synaptic vesicles. Here, we report the identification of a unique amino acid motif in the vesicular GABA transporter (VGAT) that controls its synaptic localization and activity-dependent recycling. Mutational analysis of this atypical dileucine-like motif in rat VGAT indicates that the transporter recycles by interacting with the clathrin adaptor protein AP-2. However, mutation of a single acidic residue upstream of the dileucine-like motif leads to a shift to an AP-3-dependent trafficking pathway that preferentially targets the transporter to the readily releasable and recycling pool of vesicles. Real-time imaging with a VGAT-pHluorin fusion provides a useful approach to explore how unique sorting sequences target individual proteins to synaptic vesicles with distinct functional properties.
Collapse
|
26
|
Liang Z, Demko V, Wilson RC, Johnson KA, Ahmad R, Perroud PF, Quatrano R, Zhao S, Shalchian-Tabrizi K, Otegui MS, Olsen OA, Johansen W. The catalytic domain CysPc of the DEK1 calpain is functionally conserved in land plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:742-54. [PMID: 23663131 DOI: 10.1111/tpj.12235] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 03/26/2013] [Accepted: 05/08/2013] [Indexed: 05/09/2023]
Abstract
DEK1, the single calpain of land plants, is a member of the ancient membrane bound TML-CysPc-C2L calpain family that dates back 1.5 billion years. Here we show that the CysPc-C2L domains of land plant calpains form a separate sub-clade in the DEK1 clade of the phylogenetic tree of plants. The charophycean alga Mesostigma viride DEK1-like gene is clearly divergent from those in land plants, suggesting that a major evolutionary shift in DEK1 occurred during the transition to land plants. Based on genetic complementation of the Arabidopsis thaliana dek1-3 mutant using CysPc-C2L domains of various origins, we show that these two domains have been functionally conserved within land plants for at least 450 million years. This conclusion is based on the observation that the CysPc-C2L domains of DEK1 from the moss Physcomitrella patens complements the A. thaliana dek1-3 mutant phenotype. In contrast, neither the CysPc-C2L domains from M. viride nor chimeric animal-plant calpains complement this mutant. Co-evolution analysis identified differences in the interactions between the CysPc-C2L residues of DEK1 and classical calpains, supporting the view that the two enzymes are regulated by fundamentally different mechanisms. Using the A. thaliana dek1-3 complementation assay, we show that four conserved amino acid residues of two Ca²⁺-binding sites in the CysPc domain of classical calpains are conserved in land plants and functionally essential in A. thaliana DEK1.
Collapse
Affiliation(s)
- Zhe Liang
- Norwegian University of Life Sciences, Ås, N-1432, Norway
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Van Liefferinge J, Massie A, Portelli J, Di Giovanni G, Smolders I. Are vesicular neurotransmitter transporters potential treatment targets for temporal lobe epilepsy? Front Cell Neurosci 2013; 7:139. [PMID: 24009559 PMCID: PMC3757300 DOI: 10.3389/fncel.2013.00139] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/11/2013] [Indexed: 12/18/2022] Open
Abstract
The vesicular neurotransmitter transporters (VNTs) are small proteins responsible for packing synaptic vesicles with neurotransmitters thereby determining the amount of neurotransmitter released per vesicle through fusion in both neurons and glial cells. Each transporter subtype was classically seen as a specific neuronal marker of the respective nerve cells containing that particular neurotransmitter or structurally related neurotransmitters. More recently, however, it has become apparent that common neurotransmitters can also act as co-transmitters, adding complexity to neurotransmitter release and suggesting intriguing roles for VNTs therein. We will first describe the current knowledge on vesicular glutamate transporters (VGLUT1/2/3), the vesicular excitatory amino acid transporter (VEAT), the vesicular nucleotide transporter (VNUT), vesicular monoamine transporters (VMAT1/2), the vesicular acetylcholine transporter (VAChT) and the vesicular γ-aminobutyric acid (GABA) transporter (VGAT) in the brain. We will focus on evidence regarding transgenic mice with disruptions in VNTs in different models of seizures and epilepsy. We will also describe the known alterations and reorganizations in the expression levels of these VNTs in rodent models for temporal lobe epilepsy (TLE) and in human tissue resected for epilepsy surgery. Finally, we will discuss perspectives on opportunities and challenges for VNTs as targets for possible future epilepsy therapies.
Collapse
|
28
|
Optogenetic investigation of the role of the superior colliculus in orienting movements. Behav Brain Res 2013; 255:55-63. [PMID: 23643689 DOI: 10.1016/j.bbr.2013.04.040] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 03/27/2013] [Accepted: 04/25/2013] [Indexed: 12/13/2022]
Abstract
In vivo studies have demonstrated that the superior colliculus (SC) integrates sensory information and plays a role in controlling orienting motor output. However, how the complex microcircuitry within the SC, as documented by slice studies, subserves these functions is unclear. Optogenetics affords the potential to examine, in behaving animals, the functional roles of specific neuron types that comprise heterogeneous nuclei. As a first step toward understanding how SC microcircuitry underlies motor output, we applied optogenetics to mice performing an odor discrimination task in which sensory decisions are reported by either a leftward or rightward SC-dependent orienting movement. We unilaterally expressed either channelrhodopsin-2 or halorhodopsin in the SC and delivered light in order to excite or inhibit motor-related SC activity as the movement was planned. We found that manipulating SC activity predictably affected the direction of the selected movement in a manner that depended on the difficulty of the odor discrimination. This study demonstrates that the SC plays a similar role in directional orienting movements in mice as it does in other species, and provides a framework for future investigations into how specific SC cell types contribute to motor control.
Collapse
|
29
|
Spatiotemporal resolution of BDNF neuroprotection against glutamate excitotoxicity in cultured hippocampal neurons. Neuroscience 2013; 237:66-86. [PMID: 23384605 DOI: 10.1016/j.neuroscience.2013.01.054] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 01/28/2013] [Indexed: 02/02/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) protects hippocampal neurons from glutamate excitotoxicity as determined by analysis of chromatin condensation, through activation of extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3-kinase (PI3-K) signaling pathways. However, it is still unknown whether BDNF also prevents the degeneration of axons and dendrites, and the functional demise of synapses, which would be required to preserve neuronal activity. Herein, we have studied the time-dependent changes in several neurobiological markers, and the regulation of proteolytic mechanisms in cultured rat hippocampal neurons, through quantitative western blot and immunocytochemistry. Calpain activation peaked immediately after the neurodegenerative input, followed by a transient increase in ubiquitin-conjugated proteins and increased abundance of cleaved-caspase-3. Proteasome and calpain inhibition did not reproduce the protective effect of BDNF and caspase inhibition in preventing chromatin condensation. However, proteasome and calpain inhibition did protect the neuronal markers for dendrites (MAP-2), axons (Neurofilament-H) and the vesicular glutamate transporters (VGLUT1-2), whereas caspase inhibition was unable to mimic the protective effect of BDNF on neurites and synaptic markers. BDNF partially prevented the downregulation of synaptic activity measured by the KCl-evoked glutamate release using a Förster (Fluorescence) resonance energy transfer (FRET) glutamate nanosensor. These results translate a time-dependent activation of proteases and spatial segregation of these mechanisms, where calpain activation is followed by proteasome deregulation, from neuronal processes to the soma, and finally by caspase activation in the cell body. Moreover, PI3-K and PLCγ small molecule inhibitors significantly blocked the protective action of BDNF, suggesting an activity-dependent mechanism of neuroprotection. Ultimately, we hypothesize that neuronal repair after a degenerative insult is initiated at the synaptic level.
Collapse
|
30
|
Caldeira MV, Curcio M, Leal G, Salazar IL, Mele M, Santos ARA, Melo CV, Pereira P, Canzoniero LMT, Duarte CB. Excitotoxic stimulation downregulates the ubiquitin-proteasome system through activation of NMDA receptors in cultured hippocampal neurons. Biochim Biophys Acta Mol Basis Dis 2012; 1832:263-74. [PMID: 23069389 DOI: 10.1016/j.bbadis.2012.10.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 09/20/2012] [Accepted: 10/09/2012] [Indexed: 01/30/2023]
Abstract
Overactivation of glutamate receptors contributes to neuronal damage (excitotoxicity) in ischemic stroke but the detailed mechanisms are not fully elucidated. Brain ischemia is also characterized by an impairment of the activity of the proteasome, one of the major proteolytic systems in neurons. We found that excitotoxic stimulation with glutamate rapidly decreases ATP levels and the proteasome activity, and induces the disassembly of the 26S proteasome in cultured rat hippocampal neurons. Downregulation of the proteasome activity, leading to an accumulation of ubiquitinated proteins, was mediated by calcium entry through NMDA receptors and was only observed in the nuclear fraction. Furthermore, excitotoxicity-induced proteasome inhibition was partially sensitive to cathepsin-L inhibition and was specifically induced by activation of extrasynaptic NMDA receptors. Oxygen and glucose deprivation induced neuronal death and downregulated the activity of the proteasome by a mechanism dependent on the activation of NMDA receptors. Since deubiquitinating enzymes may regulate proteins half-life by counteracting ubiquitination, we also analyzed how their activity is regulated under excitotoxic conditions. Glutamate stimulation decreased the total deubiquitinase activity in hippocampal neurons, but was without effect on the activity of Uch-L1, showing that not all deubiquitinases are affected. These results indicate that excitotoxic stimulation with glutamate has multiple effects on the ubiquitin-proteasome system which may contribute to the demise process in brain ischemia and in other neurological disorders.
Collapse
|
31
|
Puskarjov M, Ahmad F, Kaila K, Blaesse P. Activity-dependent cleavage of the K-Cl cotransporter KCC2 mediated by calcium-activated protease calpain. J Neurosci 2012; 32:11356-64. [PMID: 22895718 PMCID: PMC6621186 DOI: 10.1523/jneurosci.6265-11.2012] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 06/29/2012] [Accepted: 07/03/2012] [Indexed: 11/21/2022] Open
Abstract
The K-Cl cotransporter KCC2 plays a crucial role in neuronal chloride regulation. In mature central neurons, KCC2 is responsible for the low intracellular Cl(-) concentration ([Cl(-)](i)) that forms the basis for hyperpolarizing GABA(A) receptor-mediated responses. Fast changes in KCC2 function and expression have been observed under various physiological and pathophysiological conditions. Here, we show that the application of protein synthesis inhibitors cycloheximide and emetine to acute rat hippocampal slices have no effect on total KCC2 protein level and K-Cl cotransporter function. Furthermore, blocking constitutive lysosomal degradation with leupeptin did not induce significant changes in KCC2 protein levels. These findings indicate a low basal turnover rate of the total KCC2 protein pool. In the presence of the glutamate receptor agonist NMDA, the total KCC2 protein level decreased to about 30% within 4 h, and this effect was blocked by calpeptin and MDL-28170, inhibitors of the calcium-activated protease calpain. Interictal-like activity induced by incubation of hippocampal slices in an Mg(2+)-free solution led to a fast reduction in KCC2-mediated Cl(-) transport efficacy in CA1 pyramidal neurons, which was paralleled by a decrease in both total and plasmalemmal KCC2 protein. These effects were blocked by the calpain inhibitor MDL-28170. Taken together, these findings show that calpain activation leads to cleavage of KCC2, thereby modulating GABAergic signaling.
Collapse
Affiliation(s)
- Martin Puskarjov
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland and
| | - Faraz Ahmad
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland and
| | - Kai Kaila
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland and
| | - Peter Blaesse
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland and
- Institute of Physiology I, Westfälische Wilhelms-University Münster, D-48149 Münster, Germany
| |
Collapse
|
32
|
Abstract
The glial cell line-derived neurotrophic factor (GDNF) was first identified as a survival factor for midbrain dopaminergic neurons, but additional studies provided evidences for a role as a trophic factor for other neurons of the central and peripheral nervous systems. GDNF regulates cellular activity through interaction with glycosyl-phosphatidylinositol-anchored cell surface receptors, GDNF family receptor-α1, which might signal through the transmembrane Ret tyrosine receptors or the neural cell adhesion molecule, to promote cell survival, neurite outgrowth, and synaptogenesis. The neuroprotective effect of exogenous GDNF has been shown in different experimental models of focal and global brain ischemia, by local administration of the trophic factor, using viral vectors carrying the GDNF gene and by transplantation of GDNF-expressing cells. These different strategies and the mechanisms contributing to neuroprotection by GDNF are discussed in this review. Importantly, neuroprotection by GDNF was observed even when administered after the ischemic injury.
Collapse
Affiliation(s)
- Emília P Duarte
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal, Coimbra, Portugal
| | | | | | | |
Collapse
|
33
|
Excitotoxicity downregulates TrkB.FL signaling and upregulates the neuroprotective truncated TrkB receptors in cultured hippocampal and striatal neurons. J Neurosci 2012; 32:4610-22. [PMID: 22457507 DOI: 10.1523/jneurosci.0374-12.2012] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal survival through activation of TrkB receptors. The trkB gene encodes a full-length receptor tyrosine kinase (TrkB.FL) and its truncated (T1/T2) isoforms. We investigated the changes in TrkB protein levels and signaling activity under excitotoxic conditions, which are characteristic of brain ischemia, traumatic brain injury, and neurodegenerative disorders. Excitotoxic stimulation of cultured rat hippocampal or striatal neurons downregulated TrkB.FL and upregulated a truncated form of the receptor (TrkB.T). Downregulation of TrkB.FL was mediated by calpains, whereas the increase in TrkB.T protein levels required transcription and translation activities. Downregulation of TrkB.FL receptors in hippocampal neurons correlated with a decrease in BDNF-induced activation of the Ras/ERK and PLCγ pathways. However, calpain inhibition, which prevents TrkB.FL degradation, did not preclude the decrease in signaling activity of these receptors. On the other hand, incubation with anisomycin, to prevent the upregulation of TrkB.T, protected to a large extent the TrkB.FL signaling activity, suggesting that truncated receptors may act as dominant-negatives. The upregulation of TrkB.T under excitotoxic conditions was correlated with an increase in BDNF-induced inhibition of RhoA, a mediator of excitotoxic neuronal death. BDNF fully protected hippocampal neurons transduced with TrkB.T when present during excitotoxic stimulation with glutamate, in contrast with the partial protection observed in cells overexpressing TrkB.FL or expressing GFP. These results indicate that BDNF protects hippocampal neurons by two distinct mechanisms: through the neurotrophic effects of TrkB.FL receptors and by activation of TrkB.T receptors coupled to inhibition of the excitotoxic signaling.
Collapse
|
34
|
Buddhala C, Suarez M, Modi J, Prentice H, Ma Z, Tao R, Wu JY. Calpain cleavage of brain glutamic acid decarboxylase 65 is pathological and impairs GABA neurotransmission. PLoS One 2012; 7:e33002. [PMID: 22427928 PMCID: PMC3299728 DOI: 10.1371/journal.pone.0033002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 02/02/2012] [Indexed: 11/19/2022] Open
Abstract
Previously, we have shown that the GABA synthesizing enzyme, L-glutamic acid decarboxylase 65 (GAD65) is cleaved to form its truncated form (tGAD65) which is 2-3 times more active than the full length form (fGAD65). The enzyme responsible for cleavage was later identified as calpain. Calpain is known to cleave its substrates either under a transient physiological stimulus or upon a sustained pathological insult. However, the precise role of calpain cleavage of fGAD65 is poorly understood. In this communication, we examined the cleavage of fGAD65 under diverse pathological conditions including rats under ischemia/reperfusion insult as well as rat brain synaptosomes and primary neuronal cultures subjected to excessive stimulation with high concentration of KCl. We have shown that the formation of tGAD65 progressively increases with increasing stimulus concentration both in rat brain synaptosomes and primary rat embryo cultures. More importantly, direct cleavage of synaptic vesicle - associated fGAD65 by calpain was demonstrated and the resulting tGAD65 bearing the active site of the enzyme was detached from the synaptic vesicles. Vesicular GABA transport of the newly synthesized GABA was found to be reduced in calpain treated SVs. Furthermore, we also observed that the levels of tGAD65 in the focal cerebral ischemic rat brain tissue increased corresponding to the elevation of local glutamate as indicated by microdialysis. Moreover, the levels of tGAD65 was also proportional to the degree of cell death when the primary neuronal cultures were exposed to high KCl. Based on these observations, we conclude that calpain-mediated cleavage of fGAD65 is pathological, presumably due to decrease in the activity of synaptic vesicle - associated fGAD65 resulting in a decrease in the GABA synthesis - packaging coupling process leading to reduced GABA neurotransmission.
Collapse
Affiliation(s)
- Chandana Buddhala
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, United States of America,
| | - Marjorie Suarez
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, United States of America,
| | - Jigar Modi
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, United States of America,
| | - Howard Prentice
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, United States of America,
| | - Zhiyuan Ma
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, United States of America,
| | - Rui Tao
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, United States of America,
| | - Jang Yen Wu
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida, United States of America,
| |
Collapse
|
35
|
GABA metabolism and transport: effects on synaptic efficacy. Neural Plast 2012; 2012:805830. [PMID: 22530158 PMCID: PMC3316990 DOI: 10.1155/2012/805830] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 12/19/2011] [Indexed: 11/17/2022] Open
Abstract
GABAergic inhibition is an important regulator of excitability in neuronal networks. In addition, inhibitory synaptic signals contribute crucially to the organization of spatiotemporal patterns of network activity, especially during coherent oscillations. In order to maintain stable network states, the release of GABA by interneurons must be plastic in timing and amount. This homeostatic regulation is achieved by several pre- and postsynaptic mechanisms and is triggered by various activity-dependent local signals such as excitatory input or ambient levels of neurotransmitters. Here, we review findings on the availability of GABA for release at presynaptic terminals of interneurons. Presynaptic GABA content seems to be an important determinant of inhibitory efficacy and can be differentially regulated by changing synthesis, transport, and degradation of GABA or related molecules. We will discuss the functional impact of such regulations on neuronal network patterns and, finally, point towards pharmacological approaches targeting these processes.
Collapse
|
36
|
Lobo AC, Gomes JR, Catarino T, Mele M, Fernandez P, Inácio AR, Bahr BA, Santos AE, Wieloch T, Carvalho AL, Duarte CB. Cleavage of the vesicular glutamate transporters under excitotoxic conditions. Neurobiol Dis 2011; 44:292-303. [DOI: 10.1016/j.nbd.2011.07.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 06/21/2011] [Accepted: 07/11/2011] [Indexed: 10/17/2022] Open
|