RESUMO
Whole-brain genome editing to correct single-base mutations and reduce or reverse behavioral changes in animal models of autism spectrum disorder (ASD) has not yet been achieved. We developed an apolipoprotein B messenger RNA-editing enzyme, catalytic polypeptide-embedded cytosine base editor (AeCBE) system for converting C·G to T·A base pairs. We demonstrate its effectiveness by targeting AeCBE to an ASD-associated mutation of the MEF2C gene (c.104T>C, p.L35P) in vivo in mice. We first constructed Mef2cL35P heterozygous mice. Male heterozygous mice exhibited hyperactivity, repetitive behavior and social abnormalities. We then programmed AeCBE to edit the mutated C·G base pairs of Mef2c in the mouse brain through the intravenous injection of blood-brain barrier-crossing adeno-associated virus. This treatment successfully restored Mef2c protein levels in several brain regions and reversed the behavioral abnormalities in Mef2c-mutant mice. Our work presents an in vivo base-editing paradigm that could potentially correct single-base genetic mutations in the brain.
Assuntos
Transtorno do Espectro Autista , Edição de Genes , Animais , Camundongos , Masculino , Transtorno do Espectro Autista/genética , Encéfalo , Mutação/genética , Fatores de Transcrição MEF2/genéticaRESUMO
Aberrant inorganic phosphate (Pi) homeostasis causes brain calcification and aggravates neurodegeneration, but the underlying mechanism remains unclear. Here, we found that primary familial brain calcification (PFBC)-associated Pi transporter genes Pit2 and Xpr1 were highly expressed in astrocytes, with importer PiT2 distributed over the entire astrocyte processes and exporter XPR1 localized to astrocyte end-feet on blood vessels. This polarized PiT2 and XPR1 distribution endowed astrocyte with Pi transport capacity competent for brain Pi homeostasis, which was disrupted in mice with astrocyte-specific knockout (KO) of either Pit2 or Xpr1. Moreover, we found that Pi uptake by PiT2, and its facilitation by PFBC-associated galactosidase MYORG, were required for the high Pi transport capacity of astrocytes. Finally, brain calcification was suppressed by astrocyte-specific PiT2 re-expression in Pit2-KO mice. Thus, astrocyte-mediated Pi transport is pivotal for brain Pi homeostasis, and elevating astrocytic Pi transporter function represents a potential therapeutic strategy for reducing brain calcification.
Assuntos
Astrócitos , Encéfalo , Homeostase , Fosfatos , Proteínas Cotransportadoras de Sódio-Fosfato Tipo III , Receptor do Retrovírus Politrópico e Xenotrópico , Animais , Humanos , Camundongos , Astrócitos/metabolismo , Encéfalo/metabolismo , Calcinose/metabolismo , Calcinose/genética , Homeostase/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosfatos/metabolismo , Proteínas Cotransportadoras de Sódio-Fosfato Tipo III/metabolismo , Proteínas Cotransportadoras de Sódio-Fosfato Tipo III/genéticaRESUMO
The hypothalamus regulates innate social interactions, but how hypothalamic neurons transduce sex-related sensory signals emitted by conspecifics to trigger appropriate behaviors remains unclear. Here, we addressed this issue by identifying specific hypothalamic neurons required for sensing conspecific male cues relevant to inter-male aggression. By in vivo recording of neuronal activities in behaving mice, we showed that neurons expressing dopamine transporter (DAT+) in the ventral premammillary nucleus (PMv) of the hypothalamus responded to male urine cues in a vomeronasal organ (VNO)-dependent manner in naive males. Retrograde trans-synaptic tracing further revealed a specific group of neurons in the bed nucleus of the stria terminalis (BNST) that convey male-relevant signals from VNO to PMv. Inhibition of PMvDAT+ neurons abolished the preference for male urine cues and reduced inter-male attacks, while activation of these neurons promoted urine marking and aggression. Thus, PMvDAT+ neurons exemplify a hypothalamic node that transforms sex-related chemo-signals into recognition and behaviors.
Assuntos
Agressão/psicologia , Sinais (Psicologia) , Hipotálamo Posterior/fisiologia , Neurônios/fisiologia , Urina/fisiologia , Agressão/fisiologia , Animais , Clozapina/análogos & derivados , Clozapina/farmacologia , Feminino , Masculino , Camundongos , Ratos , Núcleos Septais/fisiologia , Órgão Vomeronasal/fisiologiaRESUMO
OBJECTIVE: To investigate the mechanisms of excitotoxic effects of glutamate on human neuroblastoma SH-SY5Y cells. METHODS: SH-SY5Y cell viability was measured by MTT assay. Other damaged profile was detected by lactate dehydrogenase (LDH) release and by 4', 6-diamidino-2-phenylindole (DAPI) staining. The cytosolic calcium concentration was tested by calcium influx assay. The glutamate-induced oxidative stress was analyzed by cytosolic glutathione assay, superoxide dismutase (SOD) assay and extracellular malondialdehyde (MDA) assay. RESULTS: Glutamate treatment caused damage in SH-SY5Y cells, including the decrease of cell viability, the increase of LDH release and the alterations of morphological structures. Furthermore, the concentration of cytoplasmic calcium in SH-SY5Y cells was not changed within 20 min following glutamate treatment, while cytosolic calcium concentration significantly increased within 24 h after glutamate treatment, which could not be inhibited by MK801, an antagonist of NMDA receptors, or by LY341495, an antagonist of metabotropic glutamate receptors. On the other hand, oxidative damage was observed in SH-SY5Y cells treated with glutamate, including decreases in glutathione content and SOD activity, and elevation of MDA level, all of which could be alleviated by an antioxidant Tanshinone IIA (Tan IIA, a major active ingredient from a Chinese plant Salvia Miltiorrhiza Bge). CONCLUSION: Glutamate exerts toxicity in human neuroblastoma SH-SY5Y cells possibly through oxidative damage, not through calcium homeostasis destruction mediated by NMDA receptors.