Among children and adults with the Lennox-Gastaut syndrome, the addition of cannabidiol at a dose of 10 mg or 20 mg per kilogram per day to a conventional antiepileptic regimen resulted in greater reductions in the frequency of drop seizures than placebo. Adverse events with cannabidiol included elevated liver aminotransferase concentrations. (Funded by GW Pharmaceuticals; GWPCARE3 ClinicalTrials.gov number, NCT02224560 .).

Adenosine deaminases acting on RNA (ADARs) catalyze the hydrolytic deamination of adenosine to inosine in double-stranded RNA (dsRNA) and thereby potentially alter the information content and structure of cellular RNAs. Notably, although the overwhelming majority of such editing events occur in transcripts derived from Alu repeat elements, the biological function of non-coding RNA editing remains uncertain. Here, we show that mutations in ADAR1 (also known as ADAR) cause the autoimmune disorder Aicardi-Goutières syndrome (AGS). As in Adar1-null mice, the human disease state is associated with upregulation of interferon-stimulated genes, indicating a possible role for ADAR1 as a suppressor of type I interferon signaling. Considering recent insights derived from the study of other AGS-related proteins, we speculate that ADAR1 may limit the cytoplasmic accumulation of the dsRNA generated from genomic repetitive elements.

SummaryThe ADAR RNA-editing enzymes deaminate adenosine bases to inosines in cellular RNAs. Aberrant interferon expression occurs in patients in whom ADAR1 mutations cause Aicardi-Goutières syndrome (AGS) or dystonia arising from striatal neurodegeneration. Adar1 mutant mouse embryos show aberrant interferon induction and die by embryonic day E12.5. We demonstrate that Adar1 embryonic lethality is rescued to live birth in Adar1; Mavs double mutants in which the antiviral interferon induction response to cytoplasmic double-stranded RNA (dsRNA) is prevented. Aberrant immune responses in Adar1 mutant mouse embryo fibroblasts are dramatically reduced by restoring the expression of editing-active cytoplasmic ADARs. We propose that inosine in cellular RNA inhibits antiviral inflammatory and interferon responses by altering RLR interactions. Transfecting dsRNA oligonucleotides containing inosine-uracil base pairs into Adar1 mutant mouse embryo fibroblasts reduces the aberrant innate immune response. ADAR1 mutations causing AGS affect the activity of the interferon-inducible cytoplasmic isoform more severely than the nuclear isoform.

ObjectiveTo evaluate the safety and preliminary pharmacokinetics of a pharmaceutical formulation of purified cannabidiol (CBD) in children with Dravet syndrome.MethodsPatients aged 4–10 years were randomized 4:1 to CBD (5, 10, or 20 mg/kg/d) or placebo taken twice daily. The double-blind trial comprised 4-week baseline, 3-week treatment (including titration), 10-day taper, and 4-week follow-up periods. Completers could continue in an open-label extension. Multiple pharmacokinetic blood samples were taken on the first day of dosing and at end of treatment for measurement of CBD, its metabolites 6-OH-CBD, 7-OH-CBD, and 7-COOH-CBD, and antiepileptic drugs (AEDs; clobazam and metabolite N-desmethylclobazam [N-CLB], valproate, levetiracetam, topiramate, and stiripentol). Safety assessments were clinical laboratory tests, physical examinations, vital signs, ECGs, adverse events (AEs), seizure frequency, and suicidality.ResultsThirty-four patients were randomized (10, 8, and 9 to the 5, 10, and 20 mg/kg/d CBD groups, and 7 to placebo); 32 (94%) completed treatment. Exposure to CBD and its metabolites was dose-proportional (AUC0–t). CBD did not affect concomitant AED levels, apart from an increase in N-CLB (except in patients taking stiripentol). The most common AEs on CBD were pyrexia, somnolence, decreased appetite, sedation, vomiting, ataxia, and abnormal behavior. Six patients taking CBD and valproate developed elevated transaminases; none met criteria for drug-induced liver injury and all recovered. No other clinically relevant safety signals were observed.ConclusionsExposure to CBD and its metabolites increased proportionally with dose. An interaction with N-CLB was observed, likely related to CBD inhibition of cytochrome P450 subtype 2C19. CBD resulted in more AEs than placebo but was generally well-tolerated.Classification of evidenceThis study provides Class I evidence that for children with Dravet syndrome, CBD resulted in more AEs than placebo but was generally well-tolerated.

Mitochondrial dysfunction (depolarization and structural collapse), cytosolic ATP depletion, and neuritic beading are early hallmarks of neuronal toxicity induced in a variety of pathological conditions. We show that, following global exposure to glutamate, mitochondrial changes are spatially and temporally coincident with dendritic bead formation. During oxygen-glucose deprivation, mitochondrial depolarization precedes mitochondrial collapse, which in turn is followed by dendritic beading. These events travel as a wave of activity from distal dendrites toward the neuronal cell body. Despite the spatiotemporal relationship between dysfunctional mitochondria and dendritic beads, mitochondrial depolarization and cytoplasmic ATP depletion do not trigger these events. However, mitochondrial dysfunction increases neuronal vulnerability to these morphological changes during normal physiological activity. Our findings support a mechanism whereby, during glutamate excitotoxicity, Ca 2؉ influx leads to mitochondrial depolarization, whereas Na ؉ influx leads to an unsustainable increase in ATP demand (Na ؉ ,K ؉ -ATPase activity). This leads to a drop in ATP levels, an accumulation of intracellular Na ؉ ions, and the subsequent influx of water, leading to microtubule depolymerization, mitochondrial collapse, and dendritic beading. Following the removal of a glutamate challenge, dendritic recovery is dependent upon the integrity of the mitochondrial membrane potential, but not on a resumption of ATP synthesis or Na ؉ ,K ؉ -ATPase activity. Thus, dendritic recovery is not a passive reversal of the events that induce dendritic beading. These findings suggest that the degree of calcium influx and mitochondrial depolarization inflicted by a neurotoxic challenge, determines the ability of the neuron to recover its normal morphology.Mitochondrial dysfunction, dendritic spine remodeling, and the formation of neuritic beads are early hallmarks of neuronal toxicity induced in a variety of pathological conditions (1-6). In particular, in Alzheimer disease, the existence of extracellular amyloid plaques and intracellular neurofibrillary tangles have been associated with neuritic beading, spine loss, neurite breakage, and shaft atrophy (7-10).An understanding of the importance of mitochondrial dysfunction in neurological diseases continues to grow. Mitochondria are highly dynamic organelles with their trafficking and elongated morphology being regulated by neuronal (11, 12) and mitochondrial (13) activity. It appears that mitochondrial transport, morphology, and function are affected by physiological processes such as synaptic transmission and pathological processes such as excitotoxicity.Despite the fact that mitochondrial dysfunction and dendritic beading are both initiated by glutamate excitotoxicity, these events are believed to be independent due to their distinct requirements for Ca 2ϩ (1-4, 6, 14) versus Na ϩ (2, 3) influx. Moreover, dendritic beading occurs much more rapidly than Ca 2ϩ -dependent excitotoxic cell death (2, 3). ...

RIC-3 has been identified as a chaperone molecule involved in promoting the functional expression of nicotinic acetylcholine and 5-HT 3 receptors in mammalian cells. In this study, we examined the effects of RIC-3a (isoform a) and a truncated isoform (isoform d) on RIC-3 localization, mobility, and aggregation and its effect on 5-HT3 receptor composition in mammalian cells. Human RIC-3a possesses an amino-terminal signal sequence that targets it to the endoplasmic reticulum where it is distributed within the reticular network, often forming large diffuse "slicks" and bright "halo" structures. RIC-3a is highly mobile within and between these compartments. Despite the propensity for RIC-3a to aggregate, its expression enhances the level of surface 5-HT3A (homomeric) receptors. In contrast, RIC-3a exerts an inhibitory action on the surface expression of heteromeric 5-HT3A/B receptors. RIC-3d exhibits an altered subcellular distribution, being localized to the endoplasmic reticulum, large diffuse slicks, tubulo-vesicular structures, and the Golgi. Bidirectional trafficking between the endoplasmic reticulum and Golgi suggests that RIC-3d constitutively cycles between these two compartments. In support of the large coiledcoil domain of RIC-3a being responsible for protein aggregation, RIC-3d, lacking this cytoplasmic domain, does not aggregate or induce the formation of bright aggregates. Regardless of these differences, isoform d is still capable of enhancing homomeric, and inhibiting heteromeric, 5-HT3 receptor expression. Thus, both isoforms of RIC-3 play a role in determining 5-HT3 receptor composition.The ligand-gated ion channels are critical participants in cellular communication, playing a major role in synaptic transmission. The ligand-gated ion channels include receptors for acetylcholine (nACh) 3 , ␥-aminobutyric acid type A, serotonin (5-HT), and glycine (the cys-loop superfamily) and N-methyl-D-aspartic acid, kainate, and AMPA (glutamate receptors). A vast array of receptor-interacting proteins have been identified as participating in receptor trafficking and localization (1) and have led to dramatic advances in our knowledge of synaptic architecture and plasticity.Chaperone molecules play an important role in the intracellular transport of receptors. However, a fundamental question in neurobiology remains: How is receptor biogenesis orchestrated? Despite the fact that receptor composition determines receptor function and their pharmacological repertoire, little information is available regarding how this may be achieved. Specific assembly signals exist that can determine a preference for particular subunit partners (2). However, few selective chaperone molecules have been implicated in the process of receptor biogenesis. General chaperone proteins such as BiP, calnexin, calreticulin, and PDI do operate on the ligand-gated ion channels but offer no specificity. In contrast, molecules such as stargazin (3), PSD-95 (4), 14-3-3 (5), and RIC-3 (6) (7-12) are beginning to offer insight into protein-specific ch...

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Neuronal calcium sensor-1 (NCS-1), the mammalian orthologue of frequenin, belongs to a family of EF-handcontaining Ca 2؉ sensors. NCS-1/frequenin has been shown to enhance synaptic transmission in PC12 cells and Drosophila and Xenopus, respectively. However, the precise molecular mechanism for the enhancement of exocytosis is largely unknown. In PC12 cells, NCS-1 potentiated exocytosis evoked by ATP, an agonist to phospholipase C-linked receptors, but had no effect on depolarization-evoked release. NCS-1 also enhanced exocytosis triggered by ionomycin,