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1.
Artigo em Russo | MEDLINE | ID: mdl-38640218

RESUMO

According to the Argentinian Ministry of Health records the number of patients requesting vasectomy increased twelve times in public hospitals in 2015-2019. The physicians and specialists account for this change in recent years, arguing, among other reasons, cultural change when male assumes active position in contraceptive methods. The article addresses vasectomized patient trajectory at the Buenos Aires University Clinical Hospital "José de San Martín". The purpose of the study was to define from sociological point of view if we are actually witnessing cultural change. While considering last ten years (2012-2022), through diachronic analysis of patient demand at the Male Fertility Laboratory (n=1136) it was found that although main motivation is fertility, minority (6%) consulting to confirm absence of sperm in the ejaculate following vasectomy increased significantly in 2022 (Pearson's chi-squared test p<0.0001). After qualitative/quantitative interviews of former patient group (n=36) two sub-populations were distinguished: childless (42%; Median age: 30 years old; range: 24-35) and those having a family (58%; Median age: 39 years old; range: 35-54). Most of them had University degree (67%) and learned about this anti-contraceptive method by the Internet. It is remarkable that 94% of them were not aware of the the Argentinian Law № 236139 of 2006 that grants their right to vasectomy. Among all patients randomly interviewed in 2022 (n=200) condom anti-contraceptive method was the best known (67%). The conclusion was made that in the meantime developed New Trend that comprises high educational level segment of population of Argentina that in the future can become the germ of Cultural Change encompassing the whole society.


Assuntos
Sêmen , Vasectomia , Humanos , Masculino , Adulto , Universidades , Fertilidade , Hospitais
2.
Nat Neurosci ; 27(4): 629-642, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38472649

RESUMO

The formation of mammalian synapses entails the precise alignment of presynaptic release sites with postsynaptic receptors but how nascent cell-cell contacts translate into assembly of presynaptic specializations remains unclear. Guided by pioneering work in invertebrates, we hypothesized that in mammalian synapses, liprin-α proteins directly link trans-synaptic initial contacts to downstream steps. Here we show that, in human neurons lacking all four liprin-α isoforms, nascent synaptic contacts are formed but recruitment of active zone components and accumulation of synaptic vesicles is blocked, resulting in 'empty' boutons and loss of synaptic transmission. Interactions with presynaptic cell adhesion molecules of either the LAR-RPTP family or neurexins via CASK are required to localize liprin-α to nascent synaptic sites. Liprin-α subsequently recruits presynaptic components via a direct interaction with ELKS proteins. Thus, assembly of human presynaptic terminals is governed by a hierarchical sequence of events in which the recruitment of liprin-α proteins by presynaptic cell adhesion molecules is a critical initial step.


Assuntos
Sinapses , Transmissão Sináptica , Animais , Humanos , Sinapses/fisiologia , Transmissão Sináptica/fisiologia , Neurônios/fisiologia , Proteínas de Transporte/metabolismo , Terminações Pré-Sinápticas/metabolismo , Moléculas de Adesão Celular , Mamíferos/metabolismo
3.
Science ; 383(6685): 890-897, 2024 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-38386755

RESUMO

Recordings of the physiological history of cells provide insights into biological processes, yet obtaining such recordings is a challenge. To address this, we introduce a method to record transient cellular events for later analysis. We designed proteins that become labeled in the presence of both a specific cellular activity and a fluorescent substrate. The recording period is set by the presence of the substrate, whereas the cellular activity controls the degree of the labeling. The use of distinguishable substrates enabled the recording of successive periods of activity. We recorded protein-protein interactions, G protein-coupled receptor activation, and increases in intracellular calcium. Recordings of elevated calcium levels allowed selections of cells from heterogeneous populations for transcriptomic analysis and tracking of neuronal activities in flies and zebrafish.


Assuntos
Cálcio , Fenômenos Fisiológicos Celulares , Células , Coloração e Rotulagem , Animais , Corantes , Perfilação da Expressão Gênica , Peixe-Zebra , Células/química , Domínios e Motivos de Interação entre Proteínas
4.
PLoS Pathog ; 19(8): e1011562, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37578957

RESUMO

Toscana virus is a major cause of arboviral disease in humans in the Mediterranean basin during summer. However, early virus-host cell interactions and entry mechanisms remain poorly characterized. Investigating iPSC-derived human neurons and cell lines, we found that virus binding to the cell surface was specific, and 50% of bound virions were endocytosed within 10 min. Virions entered Rab5a+ early endosomes and, subsequently, Rab7a+ and LAMP-1+ late endosomal compartments. Penetration required intact late endosomes and occurred within 30 min following internalization. Virus entry relied on vacuolar acidification, with an optimal pH for viral membrane fusion at pH 5.5. The pH threshold increased to 5.8 with longer pre-exposure of virions to the slightly acidic pH in early endosomes. Strikingly, the particles remained infectious after entering late endosomes with a pH below the fusion threshold. Overall, our study establishes Toscana virus as a late-penetrating virus and reveals an atypical use of vacuolar acidity by this virus to enter host cells.


Assuntos
Vírus da Febre do Flebótomo Napolitano , Humanos , Endocitose , Endossomos/metabolismo , Vacúolos , Internalização do Vírus , Concentração de Íons de Hidrogênio
5.
Nat Commun ; 14(1): 2999, 2023 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-37225702

RESUMO

The primary somatosensory cortex (S1) is a hub for body sensation of both innocuous and noxious signals, yet its role in somatosensation versus pain is debated. Despite known contributions of S1 to sensory gain modulation, its causal involvement in subjective sensory experiences remains elusive. Here, in mouse S1, we reveal the involvement of cortical output neurons in layers 5 (L5) and 6 (L6) in the perception of innocuous and noxious somatosensory signals. We find that L6 activation can drive aversive hypersensitivity and spontaneous nocifensive behavior. Linking behavior to neuronal mechanisms, we find that L6 enhances thalamic somatosensory responses, and in parallel, strongly suppresses L5 neurons. Directly suppressing L5 reproduced the pronociceptive phenotype induced by L6 activation, suggesting an anti-nociceptive function for L5 output. Indeed, L5 activation reduced sensory sensitivity and reversed inflammatory allodynia. Together, these findings reveal a layer-specific and bidirectional role for S1 in modulating subjective sensory experiences.


Assuntos
Afeto , Córtex Somatossensorial , Animais , Camundongos , Hiperalgesia , Neurônios , Dor
6.
Mol Psychiatry ; 28(5): 2122-2135, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36782060

RESUMO

MYT1L is an autism spectrum disorder (ASD)-associated transcription factor that is expressed in virtually all neurons throughout life. How MYT1L mutations cause neurological phenotypes and whether they can be targeted remains enigmatic. Here, we examine the effects of MYT1L deficiency in human neurons and mice. Mutant mice exhibit neurodevelopmental delays with thinner cortices, behavioural phenotypes, and gene expression changes that resemble those of ASD patients. MYT1L target genes, including WNT and NOTCH, are activated upon MYT1L depletion and their chemical inhibition can rescue delayed neurogenesis in vitro. MYT1L deficiency also causes upregulation of the main cardiac sodium channel, SCN5A, and neuronal hyperactivity, which could be restored by shRNA-mediated knockdown of SCN5A or MYT1L overexpression in postmitotic neurons. Acute application of the sodium channel blocker, lamotrigine, also rescued electrophysiological defects in vitro and behaviour phenotypes in vivo. Hence, MYT1L mutation causes both developmental and postmitotic neurological defects. However, acute intervention can normalise resulting electrophysiological and behavioural phenotypes in adulthood.


Assuntos
Transtorno do Espectro Autista , Animais , Humanos , Camundongos , Transtorno do Espectro Autista/tratamento farmacológico , Transtorno do Espectro Autista/genética , Transtorno Autístico/tratamento farmacológico , Transtorno Autístico/genética , Haploinsuficiência/genética , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Fenótipo , Fatores de Transcrição/genética
7.
J Clin Invest ; 133(7)2023 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-36719741

RESUMO

Multiple sclerosis (MS) is a progressive inflammatory demyelinating disease of the CNS. Increasing evidence suggests that vulnerable neurons in MS exhibit fatal metabolic exhaustion over time, a phenomenon hypothesized to be caused by chronic hyperexcitability. Axonal Kv7 (outward-rectifying) and oligodendroglial Kir4.1 (inward-rectifying) potassium channels have important roles in regulating neuronal excitability at and around the nodes of Ranvier. Here, we studied the spatial and functional relationship between neuronal Kv7 and oligodendroglial Kir4.1 channels and assessed the transcriptional and functional signatures of cortical and retinal projection neurons under physiological and inflammatory demyelinating conditions. We found that both channels became dysregulated in MS and experimental autoimmune encephalomyelitis (EAE), with Kir4.1 channels being chronically downregulated and Kv7 channel subunits being transiently upregulated during inflammatory demyelination. Further, we observed that pharmacological Kv7 channel opening with retigabine reduced neuronal hyperexcitability in human and EAE neurons, improved clinical EAE signs, and rescued neuronal pathology in oligodendrocyte-Kir4.1-deficient (OL-Kir4.1-deficient) mice. In summary, our findings indicate that neuron-OL compensatory interactions promoted resilience through Kv7 and Kir4.1 channels and identify pharmacological activation of nodal Kv7 channels as a neuroprotective strategy against inflammatory demyelination.


Assuntos
Encefalomielite Autoimune Experimental , Esclerose Múltipla , Camundongos , Animais , Humanos , Nós Neurofibrosos/metabolismo , Potássio/metabolismo , Neurônios/metabolismo , Oligodendroglia/metabolismo , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/metabolismo , Esclerose Múltipla/genética , Esclerose Múltipla/metabolismo
8.
Neuron ; 109(20): 3283-3297.e11, 2021 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-34672983

RESUMO

Deep brain temperature detection by hypothalamic warm-sensitive neurons (WSNs) has been proposed to provide feedback information relevant for thermoregulation. WSNs increase their action potential firing rates upon warming, a property that has been presumed to rely on the composition of thermosensitive ion channels within WSNs. Here, we describe a synaptic mechanism that regulates temperature sensitivity of preoptic WSNs and body temperature. Experimentally induced warming of the mouse hypothalamic preoptic area in vivo triggers body cooling. TRPM2 ion channels facilitate this homeostatic response and, at the cellular level, enhance temperature responses of WSNs, thereby linking WSN function with thermoregulation for the first time. Rather than acting within WSNs, we-unexpectedly-find TRPM2 to temperature-dependently increase synaptic drive onto WSNs by disinhibition. Our data emphasize a network-based interoceptive paradigm that likely plays a key role in encoding body temperature and that may facilitate integration of diverse inputs into thermoregulatory pathways.


Assuntos
Regulação da Temperatura Corporal/genética , Inibição Neural/genética , Neurônios/metabolismo , Área Pré-Óptica/metabolismo , Canais de Cátion TRPM/genética , Sensação Térmica/genética , Animais , Temperatura Corporal , Regulação da Temperatura Corporal/fisiologia , Interocepção/fisiologia , Camundongos , Camundongos Knockout , Área Pré-Óptica/citologia , Sinapses , Canais de Cátion TRPM/metabolismo
9.
J Virol ; 95(10)2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33658344

RESUMO

Infection with the Zika virus (ZIKV), a member of the Flaviviridae family, can cause serious neurological disorders, most notably microcephaly in newborns. Here we investigated the innate immune response to ZIKV infection in cells of the nervous system. In human neural progenitor cells (hNPCs), a target for ZIKV infection and likely involved in ZIKV-associated neuropathology, viral infection failed to elicit an antiviral interferon (IFN) response. However, pharmacological inhibition of TLR3 partially restored this deficit. Analogous results were obtained in human iPSC-derived astrocytes, which are capable of mounting a strong antiviral cytokine response. There, ZIKV is sensed by both RIG-I and MDA5 and induces an IFN response as well as expression of pro-inflammatory cytokines such as interleukin-6 (IL-6). Upon inhibition of TLR3, also in astrocytes the antiviral cytokine response was enhanced, whereas amounts of pro-inflammatory cytokines were reduced. To study the underlying mechanism, we used human epithelial cells as an easy to manipulate model system. We found that ZIKV is sensed in these cells by RIG-I to induce a robust IFN response and by TLR3 to trigger the expression of pro-inflammatory cytokines, including IL-6. ZIKV induced upregulation of IL-6 activated the STAT3 pathway, which decreased STAT1 phosphorylation in a SOCS-3 dependent manner, thus reducing the IFN response. In conclusion, we show that TLR3 activation by ZIKV suppresses IFN responses triggered by RIG-I-like receptors.ImportanceZika virus (ZIKV) has a pronounced neurotropism and infections with this virus can cause serious neurological disorders, most notably microcephaly and the Guillain-Barré syndrome. Our studies reveal that during ZIKV infection, recognition of viral RNA by TLR3 enhances the production of inflammatory cytokines and suppresses the interferon response triggered by RIG-I-like receptors (RLR) in a SOCS3-dependent manner, thus facilitating virus replication. The discovery of this crosstalk between antiviral (RLR) and inflammatory (TLR) responses may have important implications for our understanding of ZIKV-induced pathogenesis.

10.
J Clin Invest ; 131(7)2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33539324

RESUMO

Dystonia is a debilitating hyperkinetic movement disorder, which can be transmitted as a monogenic trait. Here, we describe homozygous frameshift, nonsense, and missense variants in TSPOAP1, which encodes the active-zone RIM-binding protein 1 (RIMBP1), as a genetic cause of autosomal recessive dystonia in 7 subjects from 3 unrelated families. Subjects carrying loss-of-function variants presented with juvenile-onset progressive generalized dystonia, associated with intellectual disability and cerebellar atrophy. Conversely, subjects carrying a pathogenic missense variant (p.Gly1808Ser) presented with isolated adult-onset focal dystonia. In mice, complete loss of RIMBP1, known to reduce neurotransmission, led to motor abnormalities reminiscent of dystonia, decreased Purkinje cell dendritic arborization, and reduced numbers of cerebellar synapses. In vitro analysis of the p.Gly1808Ser variant showed larger spike-evoked calcium transients and enhanced neurotransmission, suggesting that RIMBP1-linked dystonia can be caused by either reduced or enhanced rates of spike-evoked release in relevant neural networks. Our findings establish a direct link between dysfunction of the presynaptic active zone and dystonia and highlight the critical role played by well-balanced neurotransmission in motor control and disease pathogenesis.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Alelos , Sinalização do Cálcio , Dendritos/metabolismo , Distúrbios Distônicos , Mutação de Sentido Incorreto , Células de Purkinje/metabolismo , Transmissão Sináptica , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Substituição de Aminoácidos , Animais , Dendritos/genética , Distúrbios Distônicos/genética , Distúrbios Distônicos/metabolismo , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout
11.
Cell ; 179(2): 498-513.e22, 2019 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-31585084

RESUMO

Neuromodulators bind to pre- and postsynaptic G protein-coupled receptors (GPCRs), are able to quickly change intracellular cyclic AMP (cAMP) and Ca2+ levels, and are thought to play important roles in neuropsychiatric and neurodegenerative diseases. Here, we discovered in human neurons an unanticipated presynaptic mechanism that acutely changes synaptic ultrastructure and regulates synaptic communication. Activation of neuromodulator receptors bidirectionally controlled synaptic vesicle numbers within nerve terminals. This control correlated with changes in the levels of cAMP-dependent protein kinase A-mediated phosphorylation of synapsin-1. Using a conditional deletion approach, we reveal that the neuromodulator-induced control of synaptic vesicle numbers was largely dependent on synapsin-1. We propose a mechanism whereby non-phosphorylated synapsin-1 "latches" synaptic vesicles to presynaptic clusters at the active zone. cAMP-dependent phosphorylation of synapsin-1 then removes the vesicles. cAMP-independent dephosphorylation of synapsin-1 in turn recruits vesicles. Synapsin-1 thereby bidirectionally regulates synaptic vesicle numbers and modifies presynaptic neurotransmitter release as an effector of neuromodulator signaling in human neurons.


Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Terminações Pré-Sinápticas/metabolismo , Sinapsinas/metabolismo , Transmissão Sináptica , Vesículas Sinápticas/metabolismo , Animais , Células Cultivadas , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Neurotransmissores/metabolismo , Receptores de Neurotransmissores/metabolismo , Transdução de Sinais
12.
J Physiol ; 597(6): 1605-1625, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30618146

RESUMO

KEY POINTS: Excitatory glutamate neurons are sparse in the rostral hypothalamic arcuate nucleus (ARC), the subregion that has received the most attention in the past. In striking contrast, excitatory neurons are far more common (by a factor of 10) in the caudal ARC, an area which has received relatively little attention. These glutamate cells may play a negative role in energy balance and food intake. They can show an increase in phosphorylated Stat-3 in the presence of leptin, are electrically excited by the anorectic neuromodulator cholecystokinin, and inhibited by orexigenic neuromodulators neuropeptide Y, met-enkephalin, dynorphin and the catecholamine dopamine. The neurons project local axonal connections that excite other ARC neurons including proopiomelanocortin neurons that can play an important role in obesity. These data are consistent with models suggesting that the ARC glutamatergic neurons may play both a rapid and a slower role in acting as anorectic neurons in CNS control of food intake and energy homeostasis. ABSTRACT: Here we interrogate a unique class of excitatory neurons in the hypothalamic arcuate nucleus (ARC) that utilizes glutamate as a fast neurotransmitter using mice expressing GFP under control of the vesicular glutamate transporter 2 (vGluT2) promoter. These neurons show a unique distribution, synaptic characterization, cellular physiology and response to neuropeptides involved in energy homeostasis. Although apparently not previously appreciated, the caudal ARC showed a far greater density of vGluT2 cells than the rostral ARC, as seen in transgenic vGluT2-GFP mice and mRNA analysis. After food deprivation, leptin induced an increase in phosphorylated Stat-3 in vGluT2-positive neurons, indicating a response to hormonal cues of energy state. Based on whole-cell recording electrophysiology in brain slices, vGluT2 neurons were spontaneously active with a spike frequency around 2 Hz. vGluT2 cells were responsive to a number of neuropeptides related to energy homeostasis; they were excited by the anorectic peptide cholecystokinin, but inhibited by orexigenic neuropeptide Y, dynorphin and met-enkephalin, consistent with an anorexic role in energy homeostasis. Dopamine, associated with the hedonic aspect of enhancing food intake, inhibited vGluT2 neurons. Optogenetic excitation of vGluT2 cells evoked EPSCs in neighbouring neurons, indicating local synaptic excitation of other ARC neurons. Microdrop excitation of ARC glutamate cells in brain slices rapidly increased excitatory synaptic activity in anorexigenic proopiomelanocortin neurons. Together these data support the perspective that vGluT2 cells may be more prevalent in the ARC than previously appreciated, and play predominantly an anorectic role in energy metabolism.


Assuntos
Núcleo Arqueado do Hipotálamo/fisiologia , Ingestão de Alimentos , Metabolismo Energético , Potenciais Pós-Sinápticos Excitadores , Neurônios/metabolismo , Potenciais de Ação , Animais , Núcleo Arqueado do Hipotálamo/citologia , Núcleo Arqueado do Hipotálamo/metabolismo , Colecistocinina/farmacologia , Dopamina/farmacologia , Dinorfinas/farmacologia , Encefalina Metionina/farmacologia , Ácido Glutâmico/metabolismo , Homeostase , Leptina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Neuropeptídeo Y/farmacologia , Pró-Opiomelanocortina/metabolismo , Fator de Transcrição STAT3/metabolismo , Proteína Vesicular 2 de Transporte de Glutamato/metabolismo
13.
EMBO J ; 37(16)2018 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-29967030

RESUMO

The active zone of presynaptic nerve terminals organizes the neurotransmitter release machinery, thereby enabling fast Ca2+-triggered synaptic vesicle exocytosis. BK-channels are Ca2+-activated large-conductance K+-channels that require close proximity to Ca2+-channels for activation and control Ca2+-triggered neurotransmitter release by accelerating membrane repolarization during action potential firing. How BK-channels are recruited to presynaptic Ca2+-channels, however, is unknown. Here, we show that RBPs (for RIM-binding proteins), which are evolutionarily conserved active zone proteins containing SH3- and FN3-domains, directly bind to BK-channels. We find that RBPs interact with RIMs and Ca2+-channels via their SH3-domains, but to BK-channels via their FN3-domains. Deletion of RBPs in calyx of Held synapses decreased and decelerated presynaptic BK-currents and depleted BK-channels from active zones. Our data suggest that RBPs recruit BK-channels into a RIM-based macromolecular active zone complex that includes Ca2+-channels, synaptic vesicles, and the membrane fusion machinery, thereby enabling tight spatio-temporal coupling of Ca2+-influx to Ca2+-triggered neurotransmitter release in a presynaptic terminal.


Assuntos
Canais de Cálcio/metabolismo , Cálcio/metabolismo , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Terminações Pré-Sinápticas/metabolismo , Vesículas Sinápticas/metabolismo , Animais , Canais de Cálcio/genética , Canais de Potássio Ativados por Cálcio de Condutância Alta/genética , Camundongos , Vesículas Sinápticas/genética , Domínios de Homologia de src
14.
Proc Natl Acad Sci U S A ; 114(38): E8081-E8090, 2017 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-28874522

RESUMO

Fast neurotransmitter release from ribbon synapses via Ca2+-triggered exocytosis requires tight coupling of L-type Ca2+ channels to release-ready synaptic vesicles at the presynaptic active zone, which is localized at the base of the ribbon. Here, we used genetic, electrophysiological, and ultrastructural analyses to probe the architecture of ribbon synapses by perturbing the function of RIM-binding proteins (RBPs) as central active-zone scaffolding molecules. We found that genetic deletion of RBP1 and RBP2 did not impair synapse ultrastructure of ribbon-type synapses formed between rod bipolar cells (RBCs) and amacrine type-2 (AII) cells in the mouse retina but dramatically reduced the density of presynaptic Ca2+ channels, decreased and desynchronized evoked neurotransmitter release, and rendered evoked and spontaneous neurotransmitter release sensitive to the slow Ca2+ buffer EGTA. These findings suggest that RBPs tether L-type Ca2+ channels to the active zones of ribbon synapses, thereby synchronizing vesicle exocytosis and promoting high-fidelity information transfer in retinal circuits.


Assuntos
Células Amácrinas/metabolismo , Canais de Cálcio Tipo L/metabolismo , Células Bipolares da Retina/metabolismo , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Proteínas Celulares de Ligação ao Retinol/metabolismo , Sinapses/metabolismo , Células Amácrinas/citologia , Animais , Canais de Cálcio Tipo L/genética , Camundongos , Camundongos Knockout , Neurotransmissores/genética , Neurotransmissores/metabolismo , Células Bipolares da Retina/citologia , Células Fotorreceptoras Retinianas Bastonetes/citologia , Proteínas Celulares de Ligação ao Retinol/genética , Sinapses/genética , Transmissão Sináptica
15.
Neuron ; 91(4): 792-807, 2016 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-27537484

RESUMO

RIMs and RIM-binding proteins (RBPs) are evolutionary conserved multidomain proteins of presynaptic active zones that are known to recruit Ca(2+) channels; in addition, RIMs perform well-recognized functions in tethering and priming synaptic vesicles for exocytosis. However, deletions of RIMs or RBPs in mice cause only partial impairments in various active zone functions and have no effect on active zone structure, as visualized by electron micrographs, suggesting that their contribution to active zone functions is limited. Here, we show in synapses of the calyx of Held in vivo and hippocampal neurons in culture that combined, but not individual, deletions of RIMs and RBPs eliminate tethering and priming of synaptic vesicles, deplete presynaptic Ca(2+) channels, and ablate active zone complexes, as analyzed by electron microscopy of chemically fixed synapses. Thus, RBPs perform unexpectedly broad roles at the active zone that together with those of RIMs are essential for all active zone functions.


Assuntos
Proteínas de Ligação ao GTP/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Celulares de Ligação ao Retinol/metabolismo , Corpo Trapezoide/metabolismo , Animais , Cálcio/metabolismo , Células Cultivadas , Proteínas de Ligação ao GTP/genética , Hipocampo/metabolismo , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/genética , Terminações Pré-Sinápticas/metabolismo , Terminações Pré-Sinápticas/ultraestrutura , Proteínas Celulares de Ligação ao Retinol/genética , Sinapses/metabolismo , Sinapses/ultraestrutura , Vesículas Sinápticas/metabolismo
16.
J Exp Med ; 213(4): 499-515, 2016 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-27001749

RESUMO

Hundreds of L1CAM gene mutations have been shown to be associated with congenital hydrocephalus, severe intellectual disability, aphasia, and motor symptoms. How such mutations impair neuronal function, however, remains unclear. Here, we generated human embryonic stem (ES) cells carrying a conditional L1CAM loss-of-function mutation and produced precisely matching control and L1CAM-deficient neurons from these ES cells. In analyzing two independent conditionally mutant ES cell clones, we found that deletion of L1CAM dramatically impaired axonal elongation and, to a lesser extent, dendritic arborization. Unexpectedly, we also detected an ∼20-50% and ∼20-30% decrease, respectively, in the levels of ankyrinG and ankyrinB protein, and observed that the size and intensity of ankyrinG staining in the axon initial segment was significantly reduced. Overexpression of wild-type L1CAM, but not of the L1CAM point mutants R1166X and S1224L, rescued the decrease in ankyrin levels. Importantly, we found that the L1CAM mutation selectively decreased activity-dependent Na(+)-currents, altered neuronal excitability, and caused impairments in action potential (AP) generation. Thus, our results suggest that the clinical presentations of L1CAM mutations in human patients could be accounted for, at least in part, by cell-autonomous changes in the functional development of neurons, such that neurons are unable to develop normal axons and dendrites and to generate normal APs.


Assuntos
Potenciais de Ação , Axônios/metabolismo , Dendritos/metabolismo , Deleção de Genes , Hidrocefalia , Molécula L1 de Adesão de Célula Nervosa/genética , Axônios/patologia , Dendritos/patologia , Células-Tronco Embrionárias Humanas , Humanos , Hidrocefalia/genética , Hidrocefalia/metabolismo , Hidrocefalia/patologia , Hidrocefalia/fisiopatologia
17.
Neuron ; 87(6): 1234-1247, 2015 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-26402606

RESUMO

Ultrafast neurotransmitter release requires tight colocalization of voltage-gated Ca(2+) channels with primed, release-ready synaptic vesicles at the presynaptic active zone. RIM-binding proteins (RIM-BPs) are multidomain active zone proteins that bind to RIMs and to Ca(2+) channels. In Drosophila, deletion of RIM-BPs dramatically reduces neurotransmitter release, but little is known about RIM-BP function in mammalian synapses. Here, we generated double conditional knockout mice for RIM-BP1 and RIM-BP2, and analyzed RIM-BP-deficient synapses in cultured hippocampal neurons and the calyx of Held. Surprisingly, we find that in murine synapses, RIM-BPs are not essential for neurotransmitter release as such, but are selectively required for high-fidelity coupling of action potential-induced Ca(2+) influx to Ca(2+)-stimulated synaptic vesicle exocytosis. Deletion of RIM-BPs decelerated action-potential-triggered neurotransmitter release and rendered it unreliable, thereby impairing the fidelity of synaptic transmission. Thus, RIM-BPs ensure optimal organization of the machinery for fast release in mammalian synapses without being a central component of the machinery itself.


Assuntos
Transportadores de Cassetes de Ligação de ATP/fisiologia , Potenciais de Ação/fisiologia , Cálcio/metabolismo , Neurotransmissores/metabolismo , Proteínas rab3 de Ligação ao GTP/fisiologia , Potenciais de Ação/efeitos dos fármacos , Animais , Cálcio/farmacologia , Canais de Cálcio Tipo N/metabolismo , Células Cultivadas , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Células HEK293 , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Humanos , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/fisiologia , Camundongos , Camundongos Knockout
18.
Neuron ; 82(5): 1088-100, 2014 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-24908488

RESUMO

SNARE-complex assembly mediates synaptic vesicle fusion during neurotransmitter release and requires that the target-SNARE protein syntaxin-1 switches from a closed to an open conformation. Although many SNARE proteins are available per vesicle, only one to three SNARE complexes are minimally needed for a fusion reaction. Here, we use high-resolution measurements of synaptic transmission in the calyx-of-Held synapse from mutant mice in which syntaxin-1 is rendered constitutively open and SNARE-complex assembly is enhanced to examine the relation between SNARE-complex assembly and neurotransmitter release. We show that enhancing SNARE-complex assembly dramatically increases the speed of evoked release, potentiates the Ca(2+)-affinity of release, and accelerates fusion-pore expansion during individual vesicle fusion events. Our data indicate that the number of assembled SNARE complexes per vesicle during fusion determines the presynaptic release probability and fusion kinetics and suggest a mechanism whereby proteins (Munc13 or RIM) may control presynaptic plasticity by regulating SNARE-complex assembly.


Assuntos
Cálcio/metabolismo , Ácido Glutâmico/metabolismo , Proteínas SNARE/metabolismo , Transmissão Sináptica , Vesículas Sinápticas/metabolismo , Sintaxina 1/metabolismo , Animais , Células HEK293 , Humanos , Fusão de Membrana/fisiologia , Camundongos , Camundongos Transgênicos , Neurônios/fisiologia , Sintaxina 1/genética
19.
Neuron ; 78(5): 785-98, 2013 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-23764284

RESUMO

Available methods for differentiating human embryonic stem cells (ESCs) and induced pluripotent cells (iPSCs) into neurons are often cumbersome, slow, and variable. Alternatively, human fibroblasts can be directly converted into induced neuronal (iN) cells. However, with present techniques conversion is inefficient, synapse formation is limited, and only small amounts of neurons can be generated. Here, we show that human ESCs and iPSCs can be converted into functional iN cells with nearly 100% yield and purity in less than 2 weeks by forced expression of a single transcription factor. The resulting ES-iN or iPS-iN cells exhibit quantitatively reproducible properties independent of the cell line of origin, form mature pre- and postsynaptic specializations, and integrate into existing synaptic networks when transplanted into mouse brain. As illustrated by selected examples, our approach enables large-scale studies of human neurons for questions such as analyses of human diseases, examination of human-specific genes, and drug screening.


Assuntos
Fenômenos Biofísicos/fisiologia , Regulação da Expressão Gênica/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Neurônios/fisiologia , Células-Tronco Pluripotentes/fisiologia , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Animais , Fenômenos Biofísicos/genética , Biofísica , Encéfalo/citologia , Cálcio/metabolismo , Células Cultivadas , Colágeno Tipo VII/genética , Estimulação Elétrica , Epidermólise Bolhosa Distrófica/genética , Epidermólise Bolhosa Distrófica/patologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/genética , Fibroblastos , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteínas de Fluorescência Verde/genética , Humanos , Camundongos , Microscopia Confocal , Proteínas Munc18/genética , Proteínas Munc18/metabolismo , Mutação/genética , Proteínas do Tecido Nervoso/genética , Técnicas de Patch-Clamp , RNA Interferente Pequeno/fisiologia , Rodopsina/genética , Bloqueadores dos Canais de Sódio/farmacologia , Sinapses/fisiologia , Tetrodotoxina/farmacologia , Fatores de Tempo , Transfecção
20.
Arch. venez. farmacol. ter ; 15(1): 42-51, 1996. ilus, tab
Artigo em Espanhol | LILACS | ID: lil-217648

RESUMO

En una muestra de sujetos normotensos, no obesos, con historia familiar de Hipertensión Arterial, se evaluaron las respuestas de presión arterial, frecuencia cardíaca, peso corporal, diuresis, natriuresis, kaliuresis y otros parámetros bioquímicos en relación a cambios en el consumo dietético de cloruro de sodio. Se introduce el concepto operacional de sensibilidad a la sal. en dieta hipersódica se observó elevación de cifras de presión arterial en relación a valores basales en sujetos sal-resistentes con historia familiar de Hipertensión Arterial quienes además mostraron menor diuresis que los sujetos contrarreguladores. Se encontró que la excreción urinaria de sodio y potasio del subgrupo sal-resistentes es diferente del resto de la población normotensa. Se propone un método de despistaje para identificar sujetos en riesgo de desarrollar Hipertensión Arterial de acuerdo a su sensibilidad a la sal


Assuntos
Humanos , Masculino , Feminino , Cloreto de Sódio na Dieta/efeitos adversos , Cloreto de Sódio na Dieta/administração & dosagem , Hipertensão/etiologia , Hipertensão/prevenção & controle , Natriurese/fisiologia
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