RESUMO
BACKGROUND: The VPS50 protein functions in synaptic and dense core vesicle acidification, and perturbations of VPS50 function produce behavioral changes in Caenorhabditis elegans. Patients with mutations in VPS50 show severe developmental delay and intellectual disability, characteristics that have been associated with autism spectrum disorders (ASDs). The mechanisms that link VPS50 mutations to ASD are unknown. RESULTS: To examine the role of VPS50 in mammalian brain function and behavior, we used the CRISPR/Cas9 system to generate knockouts of VPS50 in both cultured murine cortical neurons and living mice. In cultured neurons, KO of VPS50 did not affect the number of synaptic vesicles but did cause mislocalization of the V-ATPase V1 domain pump and impaired synaptic activity, likely as a consequence of defects in vesicle acidification and vesicle content. In mice, mosaic KO of VPS50 in the hippocampus altered synaptic transmission and plasticity and generated robust cognitive impairments. CONCLUSIONS: We propose that VPS50 functions as an accessory protein to aid the recruitment of the V-ATPase V1 domain to synaptic vesicles and in that way plays a crucial role in controlling synaptic vesicle acidification. Understanding the mechanisms controlling behaviors and synaptic function in ASD-associated mutations is pivotal for the development of targeted interventions, which may open new avenues for therapeutic strategies aimed at ASD and related conditions.
Assuntos
Camundongos Knockout , Vesículas Sinápticas , Animais , Camundongos , Comportamento Animal/fisiologia , Encéfalo/metabolismo , Neurônios/metabolismo , Neurônios/fisiologia , Sinapses/metabolismo , Sinapses/fisiologia , Transmissão Sináptica , Vesículas Sinápticas/metabolismo , ATPases Vacuolares Próton-Translocadoras/metabolismo , ATPases Vacuolares Próton-Translocadoras/genética , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismoRESUMO
VPS50, is an accessory protein, involved in the synaptic and dense core vesicle acidification and its alterations produce behavioral changes in C.elegans. Here, we produce the mosaic knock out (mKO) of VPS50 using CRISPR/Cas9 system in both cortical cultured neurons and whole animals to evaluate the effect of VPS50 in regulating mammalian brain function and behavior. While mKO of VPS50 does not change the number of synaptic vesicles, it produces a mislocalization of the V-ATPase pump that likely impact in vesicle acidification and vesicle content to impair synaptic and neuronal activity in cultured neurons. In mice, mKO of VPS50 in the hippocampus, alter synaptic transmission and plasticity, and generated robust cognitive impairments associate to memory formation. We propose that VPS50 is an accessory protein that aids the correct recruitment of the V-ATPase pump to synaptic vesicles, thus having a crucial role controlling synaptic vesicle acidification and hence synaptic transmission.
RESUMO
Hypothyroxinemia (Hpx) is a thyroid hormone deficiency (THD) condition highly frequent during pregnancy, which although asymptomatic for the mother, it can impair the cognitive function of the offspring. Previous studies have shown that maternal hypothyroidism increases the severity of experimental autoimmune encephalomyelitis (EAE), an autoimmune disease model for multiple sclerosis (MS). Here, we analyzed the immune response after EAE induction in the adult offspring gestated in Hpx. Mice gestated in Hpx showed an early appearance of EAE symptoms and the increase of all parameters of the disease such as: the pathological score, spinal cord demyelination, and immune cell infiltration in comparison to the adult offspring gestated in euthyroidism. Isolated CD4+CD25+ T cells from spleen of the offspring gestated in Hpx that suffer EAE showed reduced capacity to suppress proliferation of effector T cells (TEff) after being stimulated with anti-CD3 and anti-CD28 antibodies. Moreover, adoptive transfer experiments of CD4+CD25+ T cells from the offspring gestated in Hpx suffering EAE to mice that were induced with EAE showed that the receptor mice suffer more intense EAE pathological score. Even though, no significant differences were detected in the frequency of Treg cells and IL-10 content in the blood, spleen, and brain between mice gestated in Hpx or euthyroidism, T cells CD4+CD25+ from spleen have reduced capacity to differentiate in vitro to Treg and to produce IL-10. Thus, our data support the notion that maternal Hpx can imprint the immune response of the offspring suffering EAE probably due to a reduced capacity to trigger suppression. Such "imprints" on the immune system could contribute to explaining as to why adult offspring gestated in Hpx suffer earlier and more intense EAE.
Assuntos
Encefalomielite Autoimune Experimental/etiologia , Encefalomielite Autoimune Experimental/metabolismo , Hipotireoidismo/complicações , Exposição Materna/efeitos adversos , Complicações na Gravidez , Efeitos Tardios da Exposição Pré-Natal , Transferência Adotiva , Animais , Biomarcadores , Diferenciação Celular , Citocinas/metabolismo , Encefalomielite Autoimune Experimental/patologia , Encefalomielite Autoimune Experimental/terapia , Feminino , Hipotireoidismo/sangue , Hipotireoidismo/etiologia , Imunofenotipagem , Ativação Linfocitária , Contagem de Linfócitos , Metimazol/administração & dosagem , Metimazol/efeitos adversos , Camundongos , Proteína Básica da Mielina/metabolismo , Fenótipo , Gravidez , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Tireotropina/sangue , Tiroxina/sangueRESUMO
Thyroid hormones (THs) during pregnancy contribute significantly to cellular differentiation and development in several tissues of the offspring, principally the central nervous system (CNS). TH deficiencies, such as hypothyroidism or hypothyroxinemia, are highly frequent during pregnancy worldwide and known to be detrimental for the development of the fetus. The function of CNS in the offspring gestated under TH deficiency will be irreversible impaired, causing low intellectual quotient, attention deficit, and mental retardation. On the other hand, little is known about the effects of TH deficiency in the offspring immune system, being the prevalent notion that the effects are reversible and only for a while will affect the number of B and T cells. Recent studies have shown that maternal hypothyroidism can altered the function of immune system in the offspring, rendering the female offspring more susceptible to suffer autoimmune-inflammatory diseases, such as experimental autoimmune encephalomyelitis (EAE) and to be more resistant to a bacterial infection. In this article we discuss these recent findings, as well as the possible mechanisms underlying these effects and the potential implications for human health.
Assuntos
Sistema Nervoso Central/fisiologia , Filho de Pais com Deficiência , Encefalomielite Autoimune Experimental , Hipotireoidismo/imunologia , Fatores Sexuais , Hormônios Tireóideos/metabolismo , Animais , Diferenciação Celular , Suscetibilidade a Doenças , Feminino , Humanos , Hipotireoidismo/genética , Camundongos , Mães , Gravidez , Complicações na Gravidez/genética , Hormônios Tireóideos/genéticaRESUMO
Dendrite arbor growth, or dendritogenesis, is choreographed by a diverse set of cues, including the NMDA receptor (NMDAR) subunits NR2A and NR2B. While NR1NR2B receptors are predominantly expressed in immature neurons and promote plasticity, NR1NR2A receptors are mainly expressed in mature neurons and induce circuit stability. How the different subunits regulate these processes is unclear, but this is likely related to the presence of their distinct C-terminal sequences that couple different signaling proteins. Calcium-calmodulin-dependent protein kinase II (CaMKII) is an interesting candidate as this protein can be activated by calcium influx through NMDARs. CaMKII triggers a series of biochemical signaling cascades, involving the phosphorylation of diverse targets. Among them, the activation of cAMP response element-binding protein (CREB-P) pathway triggers a plasticity-specific transcriptional program through unknown epigenetic mechanisms. Here, we found that dendritogenesis in hippocampal neurons is impaired by several well-characterized constructs (i.e., NR2B-RS/QD) and peptides (i.e., tatCN21) that specifically interfere with the recruitment and interaction of CaMKII with the NR2B C-terminal domain. Interestingly, we found that transduction of NR2AΔIN, a mutant NR2A construct with increased interaction to CaMKII, reactivates dendritogenesis in mature hippocampal neurons in vitro and in vivo. To gain insights into the signaling and epigenetic mechanisms underlying NMDAR-mediated dendritogenesis, we used immunofluorescence staining to detect CREB-P and acetylated lysine 27 of histone H3 (H3K27ac), an activation-associated histone tail mark. In contrast to control mature neurons, our data shows that activation of the NMDAR/CaMKII/ERK-P/CREB-P signaling axis in neurons expressing NR2AΔIN is not correlated with increased nuclear H3K27ac levels.
Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Dendritos/enzimologia , Hipocampo/enzimologia , Histonas/metabolismo , Neurogênese , Plasticidade Neuronal , Receptores de N-Metil-D-Aspartato/metabolismo , Acetilação , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/antagonistas & inibidores , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Células Cultivadas , Dendritos/efeitos dos fármacos , Idade Gestacional , Hipocampo/efeitos dos fármacos , Hipocampo/embriologia , Mutação , Neurogênese/efeitos dos fármacos , Plasticidade Neuronal/efeitos dos fármacos , Peptídeos/farmacologia , Fenótipo , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Inibidores de Proteínas Quinases/farmacologia , Processamento de Proteína Pós-Traducional , Interferência de RNA , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/genética , Transdução de Sinais , TransfecçãoRESUMO
It is believed that amyloid-ß peptide (Aß), in its aggregated-oligomeric state, constitutes one of the neurotoxic factors involved in the pathogenesis of Alzheimer's disease. With the objective of studying a potential role of the peptide on synaptic transmission, we studied the effect of soluble Aß(1-40) on synaptic transmission in rat hippocampal neurons. Neurons incubated with 500 nM of Aß(1-40) peptide for 3 days presented higher levels of intracellular calcium transients, as evaluated by fluorimetric techniques. These effects of Aß were time and concentration dependent and were accompanied by increases in glutamatergic (0.8±0.2 Hz to 2.9±0.6 Hz), but not GABAergic, transmission. The analysis of pharmacologically isolated currents in treated neurons showed increases in both AMPA- and NMDA-mediated currents as compared to control. The effects of the peptide on the frequency of synaptic currents correlated well with increases in the number of SV2 puncta and of FM1-43 destaining, suggesting a presynaptic locus for the peptide. The data also shows that application of either Aß or bicuculline alone for 24 h was without effects on neurotransmission. However, their co-application induced an increase in synaptic transmission which was accompanied by synchronous discharges reminiscent to those produced by pro-convulsive drugs, such as bicuculline. In conclusion, these results suggest that the soluble form of Aß(1-40) participates in the regulation of synaptic transmission increasing excitability and producing a pre-epileptogenic state in hippocampal neurons.