Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
Filtros adicionais











País/Região como assunto
Intervalo de ano
1.
Elife ; 82019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31498083

RESUMO

Most of our knowledge on human CNS circuitry and related disorders originates from model organisms. How well such data translate to the human CNS remains largely to be determined. Human brain slice cultures derived from neurosurgical resections may offer novel avenues to approach this translational gap. We now demonstrate robust preservation of the complex neuronal cytoarchitecture and electrophysiological properties of human pyramidal neurons in long-term brain slice cultures. Further experiments delineate the optimal conditions for efficient viral transduction of cultures, enabling 'high throughput' fluorescence-mediated 3D reconstruction of genetically targeted neurons at comparable quality to state-of-the-art biocytin fillings, and demonstrate feasibility of long term live cell imaging of human cells in vitro. This model system has implications toward a broad spectrum of translational studies, regarding the validation of data obtained in non-human model systems, for therapeutic screening and genetic dissection of human CNS circuitry.

2.
Int J Mol Med ; 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31432139

RESUMO

Virotherapy using oncolytic viruses is an upcoming therapy strategy for cancer treatment. A variety of preclinical and clinical trials have indicated that adenoviruses may be used as potent agents in the treatment of a variety of cancers, and also for the treatment of brain tumors. In these studies, it has also been shown that oncovirotherapy is safe in terms of toxicity and side effects. In addition, previous studies have presented evidence for a significant role of oncovirotherapy in the activation of anti­tumor immune responses. With regard to oncolytic adenoviruses, we have demonstrated previously that the multifunctional protein Y­box binding protein­1 (YB­1) is a potent factor that was used to develop an YB­1­dependent oncolytic adenovirus (XVir­N­31). XVir­N­31 provides the opportunity for tumor­selective replication and exhibited marked oncolytic properties in a mouse glioma tumor model using therapy­resistant brain tumor initiating cells (BTICs). In a number of, but not all, patients with glioma, YB­1 is primarily located in the nucleus; this promotes XVir­N­31­replication and subsequently tumor cell lysis. However, in certain BTICs, only a small amount of YB­1 has been identified to be nuclear, and therefore virus replication is suboptimal. YB­1 in BTICs was demonstrated to be translocated into the nucleus following irradiation, which was accompanied by an enhancement in XVir­N­31 production. R28 glioma spheres implanted in living organotypic human brain slices exhibited a significantly delayed growth rate when pre­irradiated prior to XVir­N­31­infection as compared with single treatment methods. Consistent with the in vitro data, R28 glioma­bearing mice exhibited a prolonged mean and median survival following single tumor irradiation prior to intratumoral XVir­N­31 injection, compared with the single treatment methods. In conclusion, the present study demonstrated that in an experimental glioma model, tumor irradiation strengthened the effect of an XVir­N­31­based oncovirotherapy.

3.
Nat Neurosci ; 21(4): 517-529, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29507412

RESUMO

Repair of complex CNS circuitry requires newly incorporated neurons to become appropriately, functionally integrated. One approach is to direct differentiation of endogenous progenitors in situ, or ex vivo followed by transplantation. Prior studies find that newly incorporated neurons can establish long-distance axon projections, form synapses and functionally integrate in evolutionarily old hypothalamic energy-balance circuitry. We now demonstrate that postnatal neocortical connectivity can be reconstituted with point-to-point precision, including cellular integration of specific, molecularly identified projection neuron subtypes into correct positions, combined with development of appropriate long-distance projections and synapses. Using optogenetics-based electrophysiology, experiments demonstrate functional afferent and efferent integration of transplanted neurons into transcallosal projection neuron circuitry. Results further indicate that 'primed' early postmitotic neurons, including already fate-restricted deep-layer projection neurons and/or plastic postmitotic neuroblasts with partially fate-restricted potential, account for the predominant population of neurons capable of achieving this optimal level of integration.

4.
Sci Rep ; 7(1): 12249, 2017 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-28947761

RESUMO

Pathophysiological investigation of CNS-related diseases, such as epilepsy or neurodegenerative disorders, largely relies on histological studies on human post mortem tissue, tissue obtained by biopsy or resective surgery and on studies using disease models including animal models, heterologous expression systems or cell culture based approaches. However, in general it remains elusive to what extent results obtained in model systems can be directly translated to the human brain, calling for strategies allowing validation or even primary investigation in live human CNS tissue. In the work reported here, we prepared human organotypic slice cultures from access tissue of resective epilepsy surgery. Employing different culture conditions, we systematically compared artificial culturing media versus human cerbrospinal fluid (hCSF) obtained from patients with normal pressure hydrocephalus (NPH). Presented data demonstrates sustained cortical neuronal survival including not only maintenance of typical cellular electrophysiological properties and activity, such as robust action potential generation and synaptic connectivity, but also preservation of tonic and phasic network activity up to several weeks in vitro. As clearly delineated by immunocytochemistry, single cell patch clamp and extracellular recordings, we find that in contrast to artificial culturing media, hCSF significantly enhances neuron viability and maintenance of network activity.

5.
Neurology ; 88(5): 483-492, 2017 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-28053010

RESUMO

OBJECTIVE: To examine the role of mutations in GABRB3 encoding the ß3 subunit of the GABAA receptor in individual patients with epilepsy with regard to causality, the spectrum of genetic variants, their pathophysiology, and associated phenotypes. METHODS: We performed massive parallel sequencing of GABRB3 in 416 patients with a range of epileptic encephalopathies and childhood-onset epilepsies and recruited additional patients with epilepsy with GABRB3 mutations from other research and diagnostic programs. RESULTS: We identified 22 patients with heterozygous mutations in GABRB3, including 3 probands from multiplex families. The phenotypic spectrum of the mutation carriers ranged from simple febrile seizures, genetic epilepsies with febrile seizures plus, and epilepsy with myoclonic-atonic seizures to West syndrome and other types of severe, early-onset epileptic encephalopathies. Electrophysiologic analysis of 7 mutations in Xenopus laevis oocytes, using coexpression of wild-type or mutant ß3, together with α5 and γ2s subunits and an automated 2-microelectrode voltage-clamp system, revealed reduced GABA-induced current amplitudes or GABA sensitivity for 5 of 7 mutations. CONCLUSIONS: Our results indicate that GABRB3 mutations are associated with a broad phenotypic spectrum of epilepsies and that reduced receptor function causing GABAergic disinhibition represents the relevant disease mechanism.


Assuntos
Epilepsia/genética , Mutação , Receptores de GABA-A/genética , Animais , Automação Laboratorial , Criança , Pré-Escolar , Estudos de Coortes , Epilepsia/fisiopatologia , Feminino , Heterozigoto , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Recém-Nascido , Masculino , Potenciais da Membrana/fisiologia , Oócitos , Técnicas de Patch-Clamp , Fenótipo , Receptores de GABA-A/metabolismo , Xenopus laevis
6.
World Neurosurg ; 97: 538-546, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27777150

RESUMO

OBJECTIVE: Well-defined risk factors for the identification of patients with meningioma who might benefit from preoperative or early postoperative seizure prophylaxis are unknown. We investigated and quantified risk factors to determine individual risks of seizure occurrence in patients with meningioma. METHODS: A total of 634 adult patients with meningioma were included in this retrospective cohort study. Patient gender and age, tumor location, grade and volume, usage of antiepileptic drugs (AEDs) and extent of resection were determined. RESULTS: Preoperative and early postoperative seizures occurred in 15% (n = 97) and 5% (n = 21) of the patients, respectively. Overall, 502 and 418 patients were eligible for multivariate logistic regression analyses of preoperative and early postoperative seizures, respectively. Male gender (odds ratio [OR], 2.06; P = 0.009), a non-skull base location (OR, 4.43; P < 0.001), and a tumor volume of >8 cm3 (OR, 3.05; P = 0.002) were associated with a higher risk of preoperative seizures and were used to stratify the patients into 3 prognostic groups. The high-risk subgroup of patients with meningioma showed a seizure rate of >40% (OR, 9.8; P < 0.001). Only a non-skull base tumor location (OR, 2.61; P = 0.046) was identified as a significant risk factor for early postoperative seizures. AEDs did not reduce early postoperative seizure occurrence. CONCLUSIONS: Seizure prophylaxis might be considered for patients at high risk of developing seizures who are for other reasons being considered for watchful waiting instead of resection. In contrast, our data do not provide any evidence of the efficacy of perioperative AEDs in patients with meningioma.


Assuntos
Neoplasias Meníngeas/epidemiologia , Neoplasias Meníngeas/cirurgia , Meningioma/epidemiologia , Meningioma/cirurgia , Complicações Pós-Operatórias/epidemiologia , Convulsões/epidemiologia , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Causalidade , Estudos de Coortes , Comorbidade , Feminino , Alemanha/epidemiologia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/prevenção & controle , Período Pré-Operatório , Estudos Retrospectivos , Fatores de Risco , Convulsões/prevenção & controle , Distribuição por Sexo , Resultado do Tratamento , Adulto Jovem
7.
Ann Neurol ; 78(6): 917-28, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26385488

RESUMO

OBJECTIVE: Antiepileptic treatment of brain tumor patients mainly depends on the individual physician's choice rather than on well-defined predictive factors. We investigated the predictive value of defined clinical parameters to formulate a model of risk estimations for subpopulations of brain tumor patients. METHODS: We enclosed 650 patients > 18 years of age who underwent brain tumor surgery and included a number of clinical data. Logistic regressions were performed to determine the effect sizes of seizure-related risk factors and to develop prognostic scores for the occurrence of preoperative and early postoperative seizures. RESULTS: A total of 492 patients (334 gliomas) were eligible for logistic regression for preoperative seizures, and 338 patients for early postoperative seizures. Age ≤ 60 years (odds ratio [OR] = 1.66, p = 0.020), grades I and II glioma (OR = 4.00, p = 0.0002), total tumor/edema volume ≤ 64cm(3) (OR = 2.18, p = 0.0003), and frontal location (OR = 2.28, p = 0.034) demonstrated an increased risk for preoperative seizures. Isocitrate-dehydrogenase mutations (OR = 2.52, p = 0.026) were an independent risk factor in the glioma subgroup. Age ≥ 60 years (OR = 3.32, p = 0.041), total tumor/edema volume ≤ 64cm(3) (OR = 3.17, p = 0.034), complete resection (OR = 15.50, p = 0.0009), diencephalic location (OR = 12.2, p = 0.013), and high-grade tumors (OR = 5.67, p = 0.013) were significant risk factors for surgery-related seizures. Antiepileptics (OR = 1.20, p = 0.60) did not affect seizure occurrence. For seizure occurrence, patients could be stratified into 3 prognostic preoperative and into 2 prognostic early postoperative groups. INTERPRETATION: Based on the developed prognostic scores, seizure prophylaxis should be considered in high-risk patients and patient stratification for prospective studies may be feasible in the future.


Assuntos
Neoplasias Encefálicas/complicações , Glioma/complicações , Complicações Pós-Operatórias , Convulsões/etiologia , Adulto , Idoso , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/cirurgia , Feminino , Glioma/patologia , Glioma/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Período Pós-Operatório , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Convulsões/diagnóstico
8.
Expert Opin Pharmacother ; 13(12): 1807-16, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22783830

RESUMO

INTRODUCTION: Epilepsy is a serious and common chronic neurological disease with an urgent need for novel treatment options, because 30% of all epilepsy patients do not respond to currently available drugs. Retigabine/Ezogabine (RTG) is a third-generation antiepileptic drug (AED) with a novel mechanism of action. It enhances the activity of voltage-gated K(V)7 potassium channels. AREAS COVERED: The mechanism of action of RTG is reported in this paper, along with its pharmacodynamics and pharmacokinetics, based on a literature search from 1995 to 2011. Assessment of clinical efficacy and safety was performed using the published data of one Phase II and two Phase III clinical trials (RESTORE 1 and 2). EXPERT OPINION: RTG is an efficacious AED with a unique mechanism of action. It offers a new treatment option which could be particularly interesting for patients who are resistant to currently available AEDs. However, future investigations will show if such a "rational drug therapy" will be truly advantageous. RTG seems to have a low interaction profile, but its interactions with lamotrigine in particular should be further explored. Side effects are common and mainly related to the central nervous system, but also affect peripheral organs, such as the bladder, due its relaxing effect on smooth muscle. Slow titration could be an option to reduce such side effects.


Assuntos
Anticonvulsivantes/uso terapêutico , Carbamatos/uso terapêutico , Epilepsia/tratamento farmacológico , Fenilenodiaminas/uso terapêutico , Animais , Anticonvulsivantes/farmacologia , Carbamatos/farmacologia , Humanos , Canais de Potássio KCNQ/fisiologia , Moduladores de Transporte de Membrana/farmacologia , Moduladores de Transporte de Membrana/uso terapêutico , Fenilenodiaminas/farmacologia
9.
Pflugers Arch ; 460(2): 277-88, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20401729

RESUMO

KV7 voltage-gated potassium channels, encoded by the KCNQ gene family, have caught increasing interest of the scientific community for their important physiological roles, which are emphasized by the fact that four of the five so far identified members are related to different hereditary diseases. Furthermore, these channels prove to be attractive pharmacological targets for treating diseases characterized by membrane hyperexcitability. KV7 channels are expressed in brain, heart, thyroid gland, pancreas, inner ear, muscle, stomach, and intestines. They give rise to functionally important potassium currents, reduction of which results in pathologies such as long QT syndrome, diabetes, neonatal epilepsy, neuromyotonia, or progressive deafness. Here, we summarize some key traits of KV7 channels and review how their molecular deficiencies could explain diverse disease phenotypes. We also assess the therapeutic potential of KV7 channels; in particular, how the activation of KV7 channels by the compounds retigabine and R-L3 may be useful for treatment of epilepsy or cardiac arrhythmia.


Assuntos
Canalopatias/fisiopatologia , Canais de Potássio KCNQ/genética , Canais de Potássio KCNQ/fisiologia , Animais , Carbamatos/farmacologia , Canalopatias/genética , Epilepsia/tratamento farmacológico , Epilepsia/genética , Humanos , Canais de Potássio KCNQ/agonistas , Canais de Potássio KCNQ/efeitos dos fármacos , Síndrome do QT Longo/genética , Mutação , Fenilenodiaminas/farmacologia
10.
Ann Neurol ; 66(3): 415-9, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19798636

RESUMO

Absence epilepsies of childhood are heterogeneous with most cases following complex inheritance. Those cases with onset before 4 years of age represent a poorly studied subset. We screened 34 patients with early-onset absence epilepsy for mutations in SLC2A1, the gene encoding the GLUT1 glucose transporter. Mutations leading to reduced protein function were found in 12% (4/34) of patients. Two mutations arose de novo, and two were familial. These findings suggest GLUT1 deficiency underlies a significant proportion of early-onset absence epilepsy, which has both genetic counseling and treatment implications because the ketogenic diet is effective in GLUT1 deficiency.


Assuntos
Epilepsia Tipo Ausência/genética , Transportador de Glucose Tipo 1/deficiência , Transportador de Glucose Tipo 1/genética , Mutação de Sentido Incorreto/genética , Idade de Início , Criança , Pré-Escolar , Dieta Cetogênica , Epilepsia Tipo Ausência/diagnóstico , Epilepsia Tipo Ausência/dietoterapia , Feminino , Transportador de Glucose Tipo 1/metabolismo , Humanos , Masculino , Resultado do Tratamento
11.
Brain ; 131(Pt 7): 1831-44, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18577546

RESUMO

Paroxysmal exercise-induced dyskinesia (PED) can occur in isolation or in association with epilepsy, but the genetic causes and pathophysiological mechanisms are still poorly understood. We performed a clinical evaluation and genetic analysis in a five-generation family with co-occurrence of PED and epilepsy (n = 39), suggesting that this combination represents a clinical entity. Based on a whole genome linkage analysis we screened SLC2A1, encoding the glucose transporter of the blood-brain-barrier, GLUT1 and identified heterozygous missense and frameshift mutations segregating in this and three other nuclear families with a similar phenotype. PED was characterized by choreoathetosis, dystonia or both, affecting mainly the legs. Predominant epileptic seizure types were primary generalized. A median CSF/blood glucose ratio of 0.52 (normal >0.60) in the patients and a reduced glucose uptake by mutated transporters compared with the wild-type as determined in Xenopus oocytes confirmed a pathogenic role of these mutations. Functional imaging studies implicated alterations in glucose metabolism in the corticostriate pathways in the pathophysiology of PED and in the frontal lobe cortex in the pathophysiology of epileptic seizures. Three patients were successfully treated with a ketogenic diet. In conclusion, co-occurring PED and epilepsy can be due to autosomal dominant heterozygous SLC2A1 mutations, expanding the phenotypic spectrum associated with GLUT1 deficiency and providing a potential new treatment option for this clinical syndrome.


Assuntos
Coreia/genética , Epilepsia/genética , Transportador de Glucose Tipo 1/genética , Mutação , Adolescente , Adulto , Glicemia/metabolismo , Coreia/complicações , Coreia/diagnóstico por imagem , Coreia/dietoterapia , Mapeamento Cromossômico , Análise Mutacional de DNA/métodos , Eletroencefalografia , Epilepsia/complicações , Epilepsia/diagnóstico por imagem , Epilepsia/dietoterapia , Exercício , Feminino , Glucose/líquido cefalorraquidiano , Humanos , Escore Lod , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Tomografia por Emissão de Pósitrons
12.
J Clin Invest ; 118(6): 2157-68, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18451999

RESUMO

Paroxysmal dyskinesias are episodic movement disorders that can be inherited or are sporadic in nature. The pathophysiology underlying these disorders remains largely unknown but may involve disrupted ion homeostasis due to defects in cell-surface channels or nutrient transporters. In this study, we describe a family with paroxysmal exertion-induced dyskinesia (PED) over 3 generations. Their PED was accompanied by epilepsy, mild developmental delay, reduced CSF glucose levels, hemolytic anemia with echinocytosis, and altered erythrocyte ion concentrations. Using a candidate gene approach, we identified a causative deletion of 4 highly conserved amino acids (Q282_S285del) in the pore region of the glucose transporter 1 (GLUT1). Functional studies in Xenopus oocytes and human erythrocytes revealed that this mutation decreased glucose transport and caused a cation leak that alters intracellular concentrations of sodium, potassium, and calcium. We screened 4 additional families, in which PED is combined with epilepsy, developmental delay, or migraine, but not with hemolysis or echinocytosis, and identified 2 additional GLUT1 mutations (A275T, G314S) that decreased glucose transport but did not affect cation permeability. Combining these data with brain imaging studies, we propose that the dyskinesias result from an exertion-induced energy deficit that may cause episodic dysfunction of the basal ganglia, and that the hemolysis with echinocytosis may result from alterations in intracellular electrolytes caused by a cation leak through mutant GLUT1.


Assuntos
Anemia Hemolítica/etiologia , Anemia Hemolítica/genética , Cátions , Coreia/genética , Transportador de Glucose Tipo 1/genética , Transportador de Glucose Tipo 1/fisiologia , Glucose/metabolismo , Adulto , Sequência de Aminoácidos , Animais , Coreia/patologia , Eritrócitos/metabolismo , Feminino , Humanos , Masculino , Modelos Biológicos , Dados de Sequência Molecular , Esforço Físico , Xenopus
13.
J Physiol ; 586(7): 1791-801, 2008 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-18238816

RESUMO

Voltage-gated K+channels of the K(V)7 (KCNQ) family have been identified in the last 10-15 years by discovering the causative genes for three autosomal dominant diseases: cardiac arrhythmia (long QT syndrome) with or without congenital deafness (KCNQ1), a neonatal epilepsy (KCNQ2 and KCNQ3) and progressive deafness alone (KCNQ4). A fifth member of this gene family (KCNQ5) is not affected in a disease so far. Four genes (KCNQ2-5) are expressed in the nervous system. This review is focused on recent findings on the neuronal K(V)7 channelopathies, in particular on benign familial neonatal seizures (BFNS) and peripheral nerve hyperexcitability (PNH, neuromyotonia, myokymia) caused by KCNQ2 mutations. The phenotypic spectrum associated with KCNQ2 mutations is probably broader than initially thought, as patients with severe epilepsies and developmental delay, or with Rolando epilepsy have been described. With regard to the underlying molecular pathophysiology, it has been shown that mutations with very subtle changes restricted to subthreshold voltages can cause BFNS thereby proving in a human disease model that this is the relevant voltage range for these channels to modulate neuronal firing. The two mutations associated with PNH induce much more severe channel dysfunction with a dominant negative effect on wild type (WT) channels. Finally, K(V)7 channels present interesting targets for new therapeutic approaches to diseases caused by neuronal hyperexcitability, such as epilepsy, neuropathic pain, and migraine. The molecular mechanism of K(V)7 activation by retigabine, which is in phase III clinical testing to treat pharmacoresistant focal epilepsies, has been recently elucidated as a stabilization of the open conformation by binding to the pore region.


Assuntos
Canais de Potássio KCNQ/genética , Mutação/genética , Doenças do Sistema Nervoso/genética , Anticonvulsivantes/uso terapêutico , Carbamatos/uso terapêutico , Epilepsia Neonatal Benigna/tratamento farmacológico , Epilepsia Neonatal Benigna/genética , Epilepsia Neonatal Benigna/fisiopatologia , Humanos , Canais de Potássio KCNQ/química , Doenças do Sistema Nervoso/fisiopatologia , Doenças do Sistema Nervoso Periférico/genética , Doenças do Sistema Nervoso Periférico/fisiopatologia , Fenilenodiaminas/uso terapêutico
14.
J Physiol ; 586(2): 545-55, 2008 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-18006581

RESUMO

The voltage-gated potassium channels KV7.2 and KV7.3 (genes KCNQ2 and KCNQ3) constitute a major component of the M-current controlling the firing rate in many neurons. Mutations within these two channel subunits cause benign familial neonatal convulsions (BFNC). Here we identified a novel BFNC-causing mutation (E119G) in the S1-S2 region of KV7.2. Electrophysiological investigations in Xenopus oocytes using two-microelectrode voltage clamping revealed that the steady-state activation curves for E119G alone and its coexpressions with KV7.2 and/or KV7.3 wild-type (WT) channels were significantly shifted in the depolarizing direction compared to KV7.2 or KV7.2/KV7.3. These shifts reduced the relative current amplitudes for mutant channels particularly in the subthreshold range of an action potential (about 45% reduction at --50 mV for E119G compared to KV7.2, and 33% for E119G/KV7.3 compared to KV7.2/KV7.3 channels). Activation kinetics were significantly slowed for mutant channels. Our results indicate that small changes in channel gating at subthreshold voltages are sufficient to cause neonatal seizures and demonstrate the importance of the M-current for this voltage range. This was confirmed by a computer model predicting an increased burst duration for the mutation. On a molecular level, these results reveal a critical role in voltage sensing of the negatively charged E119 in S1-S2 of KV7.2, a region that-- according to molecular modelling - might interact with a positive charge in the S4 segment.


Assuntos
Epilepsia Neonatal Benigna/genética , Epilepsia Neonatal Benigna/fisiopatologia , Canal de Potássio KCNQ2/genética , Canal de Potássio KCNQ2/fisiologia , Mutação/genética , Potenciais de Ação/fisiologia , Adulto , Sequência de Aminoácidos , Animais , Criança , Simulação por Computador , Eletrofisiologia , Feminino , Humanos , Canal de Potássio KCNQ2/análise , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Oócitos/fisiologia , Técnicas de Patch-Clamp , Linhagem , Xenopus laevis
15.
Expert Opin Investig Drugs ; 15(10): 1167-77, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16989594

RESUMO

Epilepsy is one of the most common neurological disorders with a prevalence of 0.5-1%. About two-thirds of epilepsy patients respond well to anticonvulsant pharmacotherapy and become seizure free. There is a third who remain pharmacoresistant, demonstrating the pressing need for novel treatment options that could be drugs with a different mechanism of action compared with those that are currently in clinical use. During the past, many new substances have been screened for blocking or activating effects on specific ion channels, particularly those that are not targets for currently used antiepileptic drugs. This review provides an overview of new anticonvulsant compounds targeting voltage-dependent ion channels.


Assuntos
Anticonvulsivantes/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Drogas em Investigação/administração & dosagem , Epilepsia/metabolismo , Ativação do Canal Iônico/efeitos dos fármacos , Ativação do Canal Iônico/fisiologia , Animais , Epilepsia/tratamento farmacológico , Epilepsia/fisiopatologia , Humanos , Técnicas de Patch-Clamp
16.
Biophys J ; 90(6): 2235-44, 2006 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-16326905

RESUMO

Voltage-gated K+ channel activation is proposed to result from simultaneous bending of all S6 segments away from the central axis, enlarging the aperture of the pore sufficiently to permit diffusion of K+ into the water-filled central cavity. The hinge position for the bending motion of each S6 segment is proposed to be a Gly residue and/or a Pro-Val-Pro motif in Kv1-Kv4 channels. The KCNQ1 (Kv7.1) channel has Ala-336 in the Gly-hinge position and Pro-Ala-Gly. Here we show that mutation of Ala-336 to Gly in KCNQ1 increased current amplitude and shifted the voltage dependence of activation to more negative potentials, consistent with facilitation of hinge activity that favors the open state. In contrast, mutation of Ala-336 to Cys or Thr shifted the voltage dependence of activation to more positive potentials and reduced current amplitude. Mutation of the putative Gly hinge to Ala in KCNQ2 (Kv7.2) abolished channel function. Mutation-dependent changes in current amplitude, but not kinetics, were found in heteromeric KCNQ1/KCNE1 channels. Mutation of the Pro or Gly of the Pro-Ala-Gly motif to Ala abolished KCNQ1 function and introduction of Gly in front of the Ala-mutations partially recovered channel function, suggesting that flexibility at the PAG is important for channel activation.


Assuntos
Ativação do Canal Iônico/fisiologia , Canal de Potássio KCNQ1/química , Canal de Potássio KCNQ1/fisiologia , Potenciais da Membrana/fisiologia , Oócitos/fisiologia , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Células Cultivadas , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Estrutura Terciária de Proteína , Relação Estrutura-Atividade , Xenopus laevis
17.
Mol Pharmacol ; 67(4): 1009-17, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15662042

RESUMO

Retigabine (RTG) is an anticonvulsant drug with a novel mechanism of action. It activates neuronal KCNQ-type K(+) channels by inducing a large hyperpolarizing shift of steady-state activation. To identify the structural determinants of KCNQ channel activation by RTG, we constructed a set of chimeras using the neuronal K(v)7.2 (KCNQ2) channel, which is activated by RTG, and the cardiac K(v)7.1 (KCNQ1) channel, which is not affected by this drug. Substitution of either the S5 or the S6 segment in K(v)7.2 by the respective parts of K(v)7.1 led to a complete loss of activation by RTG. Trp236 in the cytoplasmic part of S5 and the conserved Gly301 in S6 (K(v)7.2), considered as the gating hinge (Ala336 in K(v)7.1), were found to be crucial for the RTG effect: mutation of these residues could either knockout the effect in K(v)7.2 or restore it partially in K(v)7.1/K(v)7.2 chimeras. We propose that RTG binds to a hydrophobic pocket formed upon channel opening between the cytoplasmic parts of S5 and S6 involving Trp236 and the channel's gate, which could well explain the strong shift in voltage-dependent activation.


Assuntos
Anticonvulsivantes/farmacologia , Carbamatos/farmacologia , Fenilenodiaminas/farmacologia , Sequência de Aminoácidos , Animais , Sítios de Ligação , Feminino , Ativação do Canal Iônico/fisiologia , Canais de Potássio KCNQ , Canal de Potássio KCNQ1 , Canal de Potássio KCNQ2 , Dados de Sequência Molecular , Mutação Puntual , Canais de Potássio de Abertura Dependente da Tensão da Membrana/efeitos dos fármacos , Xenopus laevis
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA