1. Berg JM, Lee C, Chen L, Galvan L, Cepeda C, Chen JY, Penagarikano O, Stein JL, Li A, Oguro-Ando A, Miller JA, Vashisht AA, Starks ME, Kite EP, Tam E, Gdalyahu A, Al-Sharif NB, Burkett ZD, White SA, Fears SC, Levine MS, Wohlschlegel JA, Geschwind DH. {{JAKMIP1, a Novel Regulator of Neuronal Translation, Modulates Synaptic Function and Autistic-like Behaviors in Mouse}}. {Neuron};2015 (Nov 25)
Autism spectrum disorder (ASD) is a heritable, common neurodevelopmental disorder with diverse genetic causes. Several studies have implicated protein synthesis as one among several of its potential convergent mechanisms. We originally identified Janus kinase and microtubule-interacting protein 1 (JAKMIP1) as differentially expressed in patients with distinct syndromic forms of ASD, fragile X syndrome, and 15q duplication syndrome. Here, we provide multiple lines of evidence that JAKMIP1 is a component of polyribosomes and an RNP translational regulatory complex that includes fragile X mental retardation protein, DEAD box helicase 5, and the poly(A) binding protein cytoplasmic 1. JAKMIP1 loss dysregulates neuronal translation during synaptic development, affecting glutamatergic NMDAR signaling, and results in social deficits, stereotyped activity, abnormal postnatal vocalizations, and other autistic-like behaviors in the mouse. These findings define an important and novel role for JAKMIP1 in neural development and further highlight pathways regulating mRNA translation during synaptogenesis in the genesis of neurodevelopmental disorders.
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2. Plitt M, Barnes KA, Wallace GL, Kenworthy L, Martin A. {{Resting-state functional connectivity predicts longitudinal change in autistic traits and adaptive functioning in autism}}. {Proc Natl Acad Sci U S A};2015 (Dec 1);112(48):E6699-6706.
Although typically identified in early childhood, the social communication symptoms and adaptive behavior deficits that are characteristic of autism spectrum disorder (ASD) persist throughout the lifespan. Despite this persistence, even individuals without cooccurring intellectual disability show substantial heterogeneity in outcomes. Previous studies have found various behavioral assessments [such as intelligence quotient (IQ), early language ability, and baseline autistic traits and adaptive behavior scores] to be predictive of outcome, but most of the variance in functioning remains unexplained by such factors. In this study, we investigated to what extent functional brain connectivity measures obtained from resting-state functional connectivity MRI (rs-fcMRI) could predict the variance left unexplained by age and behavior (follow-up latency and baseline autistic traits and adaptive behavior scores) in two measures of outcome-adaptive behaviors and autistic traits at least 1 y postscan (mean follow-up latency = 2 y, 10 mo). We found that connectivity involving the so-called salience network (SN), default-mode network (DMN), and frontoparietal task control network (FPTCN) was highly predictive of future autistic traits and the change in autistic traits and adaptive behavior over the same time period. Furthermore, functional connectivity involving the SN, which is predominantly composed of the anterior insula and the dorsal anterior cingulate, predicted reliable improvement in adaptive behaviors with 100% sensitivity and 70.59% precision. From rs-fcMRI data, our study successfully predicted heterogeneity in outcomes for individuals with ASD that was unaccounted for by simple behavioral metrics and provides unique evidence for networks underlying long-term symptom abatement.
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3. Vien TN, Modgil A, Abramian AM, Jurd R, Walker J, Brandon NJ, Terunuma M, Rudolph U, Maguire J, Davies PA, Moss SJ. {{Compromising the phosphodependent regulation of the GABAAR beta3 subunit reproduces the core phenotypes of autism spectrum disorders}}. {Proc Natl Acad Sci U S A};2015 (Dec 1);112(48):14805-14810.
Alterations in the efficacy of neuronal inhibition mediated by GABAA receptors (GABAARs) containing beta3 subunits are continually implicated in autism spectrum disorders (ASDs). In vitro, the plasma membrane stability of GABAARs is potentiated via phosphorylation of serine residues 408 and 409 (S408/9) in the beta3 subunit, an effect that is mimicked by their mutation to alanines. To assess if modifications in beta3 subunit expression contribute to ASDs, we have created a mouse in which S408/9 have been mutated to alanines (S408/9A). S408/9A homozygotes exhibited increased phasic, but decreased tonic, inhibition, events that correlated with alterations in the membrane stability and synaptic accumulation of the receptor subtypes that mediate these distinct forms of inhibition. S408/9A mice exhibited alterations in dendritic spine structure, increased repetitive behavior, and decreased social interaction, hallmarks of ASDs. ASDs are frequently comorbid with epilepsy, and consistent with this comorbidity, S408/9A mice exhibited a marked increase in sensitivity to seizures induced by the convulsant kainic acid. To assess the relevance of our studies using S408/9A mice for the pathophysiology of ASDs, we measured S408/9 phosphorylation in Fmr1 KO mice, a model of fragile X syndrome, the most common monogenetic cause of ASDs. Phosphorylation of S408/9 was selectively and significantly enhanced in Fmr1 KO mice. Collectively, our results suggest that alterations in phosphorylation and/or activity of beta3-containing GABAARs may directly contribute to the pathophysiology of ASDs.
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4. Wang Y, Billon C, Walker JK, Burris TP. {{Therapeutic Effect of a Synthetic RORalpha/gamma Agonist in an Animal Model of Autism}}. {ACS Chem Neurosci};2015 (Dec 3)
Autism is a developmental disorder of the nervous system associated with impaired social communication and interactions as well excessive repetitive behaviors. There are no drug therapies that directly target the pathology of this disease. The retinoic acid receptor-related orphan receptor alpha (RORalpha) is a nuclear receptor that has been demonstrated to have reduced expression in many individuals with autism spectrum disorder (ASD). Several genes that have been shown to be downregulated in individuals with ASD have also been identified as putative RORalpha target genes. Utilizing a synthetic RORalpha/gamma agonist, SR1078, that we identified previously, we demonstrate that treatment of BTBR mice (a model of autism) with SR1078 results in reduced repetitive behavior. Furthermore, these mice display increased expression of ASD-associated RORalpha target genes in both the brains of the BTBR mice and in a human neuroblastoma cell line treated with SR1078. These data suggest that pharmacological activation of RORalpha may be a method for treatment of autism.
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5. Wheeler AC, Raspa M, Bishop E, Bailey DB, Jr. {{Aggression in fragile X syndrome}}. {J Intellect Disabil Res};2015 (Dec 2)
BACKGROUND: Individuals with fragile X syndrome (FXS), especially men, have long been described as presenting with significant behavioural challenges. Despite this known aspect of the phenotype, there has been little research exploring the prevalence, frequency, nature or consequences of aggressive behaviour in FXS. METHODS: This study used survey methodology to gather caregiver reports on the types, frequency and severity of aggressive behaviour in 774 individuals with FXS. RESULTS: Based on caregiver report, nearly all (>90%) male and female individuals were reported to have engaged in some aggression over the previous 12 months, with a third of male cases and slightly fewer than 20% of female cases being described as engaging in moderate to severe aggression or being diagnosed or treated for aggression. Further, aggressive behaviours in male individuals were serious enough that 30% had caused injuries to caregivers and 22% had caused injuries to peers or friends. Sensory issues and hyperactivity were significant predictors of the frequency of aggressive acts, while sensory issues and anxiety were predictive of the severity of aggression. Traditional behaviour management techniques as well as medication was described as the most common and successful treatment options. CONCLUSIONS: Aggressive behaviours are a significant concern for a subsample of both male and female individuals with FXS. Given that sensory concerns were predictive of both the frequency and the severity of aggression suggests these behaviours may be a reactive means of escaping uncomfortable situations.
