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1.
CNS Neurosci Ther ; 2021 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-34767694

RESUMO

AIMS: This study aimed to explore the pathomechanism of a mutation on the leucine-rich glioma inactivated 1 gene (LGI1) identified in a family having autosomal dominant lateral temporal lobe epilepsy (ADLTE), using a precise knock-in mouse model. METHODS AND RESULTS: A novel LGI1 mutation, c.152A>G; p. Asp51Gly, was identified by whole exome sequencing in a Chinese family with ADLTE. The pathomechanism of the mutation was explored by generating Lgi1D51G knock-in mice that precisely phenocopied the epileptic symptoms of human patients. The Lgi1D51G / D51G mice showed spontaneous recurrent generalized seizures and premature death. The Lgi1D51G /+ mice had partial epilepsy, with half of them displaying epileptiform discharges on electroencephalography. They also showed enhanced sensitivity to the convulsant agent pentylenetetrazole. Mechanistically, the secretion of Lgi1 was impaired in the brain of the D51G knock-in mice and the protein level was drastically reduced. Moreover, the antiepileptic drugs, carbamazepine, oxcarbazepine, and sodium valproate, could prolong the survival time of Lgi1D51G / D51G mice, and oxcarbazepine appeared to be the most effective. CONCLUSIONS: We identified a novel epilepsy-causing mutation of LGI1 in humans. The Lgi1D51G /+ mouse model, precisely phenocopying epileptic symptoms of human patients, could be a useful tool in future studies on the pathogenesis and potential therapies for epilepsy.

2.
Sci Rep ; 11(1): 11997, 2021 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-34099816

RESUMO

In the brain, AMPA receptors mediate fast excitatory neurotransmission, the dysfunction of which leads to neuropsychiatric disorders. Synaptic function of AMPA receptors is tightly controlled by a protein group called transmembrane AMPAR regulatory proteins (TARPs). TARP γ-8 (also known as CACNG8) preferentially expresses in the hippocampus, cortex and subcortical regions that are critical for emotion generation indicating its association with psychiatric disorders. Here, we identified rs10420324 (T/G), a SNP located in the human CACNG8 gene, regulated reporter gene expression in vitro and TARP γ-8 expression in the human brain. A guanine at the locus (rs10420324G) suppressed transcription likely through modulation of a local G-quadruplex DNA structure. Consistent with these observations, the frequency of rs10420324G was higher in patients with anti-social personality disorder (ASPD) than in controls, indicating that rs10420324G in CACNG8 is more voluntary for ASPD. We then characterized the behavior of TARP γ-8 knockout and heterozygous mice and found that consistent with ASPD patients who often exhibit impulsivity, aggression, risk taking, irresponsibility and callousness, a decreased γ-8 expression in mice displayed similar behaviors. Furthermore, we found that a decrease in TARP γ-8 expression impaired synaptic AMPAR functions in layer 2-3 pyramidal neurons of the prefrontal cortex, a brain region that inhibition leads to aggression, thus explaining, at least partially, the neuronal basis for the behavioral abnormality. Taken together, our study indicates that TARP γ-8 expression level is associated with ASPD, and that the TARP γ-8 knockout mouse is a valuable animal model for studying this psychiatric disease.


Assuntos
Transtorno da Personalidade Antissocial/metabolismo , Canais de Cálcio/metabolismo , Córtex Cerebral/metabolismo , Hipocampo/metabolismo , Receptores de AMPA/metabolismo , Animais , Comportamento Animal , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Células HEK293 , Humanos , Camundongos Knockout , Células Piramidais/metabolismo , Receptores de Glutamato/metabolismo , Transmissão Sináptica
3.
J Biol Chem ; 295(52): 18199-18212, 2020 12 25.
Artigo em Inglês | MEDLINE | ID: mdl-33100268

RESUMO

Post-transcriptional modifications of pre-mRNAs expand the diversity of proteomes in higher eukaryotes. In the brain, these modifications diversify the functional output of many critical neuronal signal molecules. In this study, we identified a brain-specific A-to-I RNA editing that changed glutamine to arginine (Q/R) at exon 20 and an alternative splicing of exon 4 in Tmem63b, which encodes a ubiquitously expressed osmosensitive cation channel. The channel isoforms lacking exon 4 occurred in ∼80% of Tmem63b mRNAs in the brain but were not detected in other tissues, suggesting a brain-specific splicing. We found that the Q/R editing was catalyzed by Adar2 (Adarb1) and required an editing site complementary sequence located in the proximal 5' end of intron 20. Moreover, the Q/R editing was almost exclusively identified in the splicing isoform lacking exon 4, indicating a coupling between the editing and the splicing. Elimination of the Q/R editing in brain-specific Adar2 knockout mice did not affect the splicing efficiency of exon 4. Furthermore, transfection with the splicing isoform containing exon 4 suppressed the Q/R editing in primary cultured cerebellar granule neurons. Thus, our study revealed a coupling between an RNA editing and a distant alternative splicing in the Tmem63b pre-mRNA, in which the splicing plays a dominant role. Finally, physiological analysis showed that the splicing and the editing coordinately regulate Ca2+ permeability and osmosensitivity of channel proteins, which may contribute to their functions in the brain.


Assuntos
Adenosina Desaminase/fisiologia , Processamento Alternativo , Encéfalo/metabolismo , Canais de Cálcio/genética , Éxons , Edição de RNA , Precursores de RNA/genética , Proteínas de Ligação a RNA/fisiologia , Animais , Canais de Cálcio/metabolismo , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout
4.
Cell Rep ; 31(5): 107596, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32375046

RESUMO

Hypotonic stress causes the activation of swelling-activated nonselective cation channels (NSCCs), which leads to Ca2+-dependent regulatory volume decrease (RVD) and adaptive maintenance of the cell volume; however, the molecular identities of the osmosensitive NSCCs remain unclear. Here, we identified TMEM63B as an osmosensitive NSCC activated by hypotonic stress. TMEM63B is enriched in the inner ear sensory hair cells. Genetic deletion of TMEM63B results in necroptosis of outer hair cells (OHCs) and progressive hearing loss. Mechanistically, the TMEM63B channel mediates hypo-osmolarity-induced Ca2+ influx, which activates Ca2+-dependent K+ channels required for the maintenance of OHC morphology. These findings demonstrate that TMEM63B is an osmosensor of the mammalian inner ear and the long-sought cation channel mediating Ca2+-dependent RVD.


Assuntos
Audição/efeitos dos fármacos , Soluções Hipotônicas/farmacologia , Transporte de Íons/fisiologia , Concentração Osmolar , Canais de Potássio/metabolismo , Animais , Cálcio/metabolismo , Cátions/metabolismo , Tamanho Celular/efeitos dos fármacos , Camundongos Knockout , Potássio/metabolismo , Canais de Potássio/genética , Transdução de Sinais/efeitos dos fármacos
5.
J Biol Chem ; 294(47): 17889-17902, 2019 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-31628192

RESUMO

The neuropilin and tolloid-like (Neto) proteins Neto1 and Neto2 are auxiliary subunits of kainate-type glutamate receptors (KARs) that regulate KAR trafficking and gating. However, how Netos bind and regulate the biophysical functions of KARs remains unclear. Here, we found that the N-terminal domain (NTD) of glutamate receptor ionotropic kainate 2 (GluK2) binds the first complement C1r/C1s-Uegf-BMP (CUB) domain of Neto proteins (i.e. NTD-CUB1 interaction) and that the core of GluK2 (GluK2ΔNTD) binds Netos through domains other than CUB1s (core-Neto interaction). Using electrophysiological analysis in HEK293T cells, we examined the effects of these interactions on GluK2 gating, including deactivation, desensitization, and recovery from desensitization. We found that NTD deletion does not affect GluK2 fast gating kinetics, the desensitization, and the deactivation. We also observed that Neto1 and Neto2 differentially regulate GluK2 fast gating kinetics, which largely rely on the NTD-CUB1 interactions. NTD removal facilitated GluK2 recovery from desensitization, indicating that the NTD stabilizes the GluK2 desensitization state. Co-expression with Neto1 or Neto2 also accelerated GluK2 recovery from desensitization, which fully relied on the NTD-CUB1 interactions. Moreover, we demonstrate that the NTD-CUB1 interaction involves electric attraction between positively charged residues in the GluK2_NTD and negatively charged ones in the CUB1 domains. Neutralization of these charges eliminated the regulatory effects of the NTD-CUB1 interaction on GluK2 gating. We conclude that KARs bind Netos through at least two sites and that the NTD-CUB1 interaction critically regulates Neto-mediated GluK2 gating.


Assuntos
Ativação do Canal Iônico , Proteínas de Membrana/metabolismo , Receptores de Ácido Caínico/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Células HEK293 , Humanos , Proteínas de Membrana/química , Camundongos , Modelos Biológicos , Modelos Moleculares , Ligação Proteica , Domínios Proteicos , Ratos , Receptores de Ácido Caínico/química , Receptores de N-Metil-D-Aspartato/química , Deleção de Sequência
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