Subcellular organization of UBE3A in human cerebral cortex.

BackgroundLoss of UBE3A causes Angelman syndrome, whereas excess UBE3A activity appears to increase the risk for autism. Despite this powerful association with neurodevelopmental disorders, there is still much to be learned about UBE3A, including its cellular and subcellular organization in the human brain. The issue is important, since UBE3A's localization is integral to its function.MethodsWe used light and electron microscopic immunohistochemistry to study the cellular and subcellular distribution of UBE3A in the adult human cerebral cortex. Experiments were performed on multiple tissue sources, but our results focused on optimally preserved material, using surgically resected human temporal cortex of high ultrastructural quality from nine individuals.ResultsWe demonstrate that UBE3A is expressed in both glutamatergic and GABAergic neurons, and to a lesser extent in glial cells. We find that UBE3A in neurons has a non-uniform subcellular distribution. In somata, UBE3A preferentially concentrates in euchromatin-rich domains within the nucleus. Electron microscopy reveals that labeling concentrates in the head and neck of dendritic spines and is excluded from the PSD. Strongest labeling within the neuropil was found in axon terminals.ConclusionsBy highlighting the subcellular compartments in which UBE3A is likely to function in the human neocortex, our data provide insight into the diverse functional capacities of this E3 ligase. These anatomical data may help to elucidate the role of UBE3A in Angelman syndrome and autism spectrum disorder

Relationship Between Sexual Behaviors with Non-committed Relationship Partners and COVID-19 Restrictions and Notification Rates: Results from a Longitudinal Study of Gay and Bisexual Men in Australia

Introduction: COVID-19 related lockdowns have impacted the sexual activity of gay and bisexual men (GBM). We investigated trends in sexual behaviors and the COVID-19 context in which they occurred (COVID-notification rates and jurisdictional restrictions) to understand changes in the duration and severity of periods of lockdown on the sexual behavior of Australian GBM. Methods: In an online, prospective observational study of 831 GBM from May 2020 to May 2021, we investigated associations between changes in sexual behavior among Australian GBM, lockdowns, and COVID-19 notification rates through weekly surveys from May 2020 to May 2021. Results: The mean age was 45.71 years (SD: 13.93). Most identified as gay (89.0%) and 10.2% were living with HIV. There was an overall increase in the mean weekly number of non-committed relationship partners (0.53–0.90, p < 0.001). The state of Victoria experienced a significant extended COVID-19 outbreak, accompanied by severe lockdown restrictions. In response, Victorian men’s partner numbers shifted three times, while elsewhere there was an overall gradually increasing trend. Conclusions: Less severe outbreaks with shorter lockdown periods, involving fewer and geographically contained, COVID-19 notifications were accompanied by non-significant changes in sex with non-relationship partners than more severe outbreaks over extended periods and larger geographical areas

How to have sex in a pandemic: the development of strategies to prevent COVID-19 transmission in sexual encounters among gay and bisexual men in Australia

Although many studies reported on decreases in sexual partner numbers among gay and bisexual-identifying men in the early period of the COVID-19 pandemic, few studies have explored COVID-19 risk-reduction strategies. Drawing on free-text responses in an online survey (from April to July 2020), we describe the ways in which men sought to minimise the risk of COVID-19 in sexual encounters. Partner selection was an important strategy, in particular, restricting sex to men they already knew. Accounts also indicate how participants assessed risk from potential sex partners based on symptoms, residential location, recent travel, work role, and number of other sexual contacts. Less common were in situ practices, such as avoiding kissing. Participants’ responses provide insight into creative community-based responses in the early months of the pandemic, some of which have resonances with early responses to HIV. Findings are discussed in relation to the concepts of ‘lay epidemiology’ and ‘counterpublic health’. In particular, we examine how risks and health are experienced and valued in relation to local knowledges, meanings, and practices; and how practices emerge in response to dominant public health discourses that produce an idealised public based on (hetero)normative assumptions

GABAergic Neuron-Specific Loss of Ube3a Causes Angelman Syndrome-Like EEG Abnormalities and Enhances Seizure Susceptibility

Loss of maternal UBE3A causes Angelman syndrome (AS), a neurodevelopmental disorder associated with severe epilepsy. We previously implicated GABAergic deficits onto layer (L) 2/3 pyramidal neurons in the pathogenesis of neocortical hyperexcitability, and perhaps epilepsy, in AS model mice. Here we investigate consequences of selective Ube3a loss from either GABAergic or glutamatergic neurons, focusing on the development of hyperexcitability within L2/3 neocortex and in broader circuit and behavioral contexts. We find that GABAergic Ube3a loss causes AS-like increases in neocortical EEG delta power, enhances seizure susceptibility, and leads to presynaptic accumulation of clathrin-coated vesicles (CCVs) – all without decreasing GABAergic inhibition onto L2/3 pyramidal neurons. Conversely, glutamatergic Ube3a loss fails to yield EEG abnormalities, seizures, or associated CCV phenotypes, despite impairing tonic inhibition onto L2/3 pyramidal neurons. These results substantiate GABAergic Ube3a loss as the principal cause of circuit hyperexcitability in AS mice, lending insight into ictogenic mechanisms in AS

Subcellular organization of UBE3A in human cerebral cortex

Abstract Background Loss of UBE3A causes Angelman syndrome, whereas excess UBE3A activity appears to increase the risk for autism. Despite this powerful association with neurodevelopmental disorders, there is still much to be learned about UBE3A, including its cellular and subcellular organization in the human brain. The issue is important, since UBE3A’s localization is integral to its function. Methods We used light and electron microscopic immunohistochemistry to study the cellular and subcellular distribution of UBE3A in the adult human cerebral cortex. Experiments were performed on multiple tissue sources, but our results focused on optimally preserved material, using surgically resected human temporal cortex of high ultrastructural quality from nine individuals. Results We demonstrate that UBE3A is expressed in both glutamatergic and GABAergic neurons, and to a lesser extent in glial cells. We find that UBE3A in neurons has a non-uniform subcellular distribution. In somata, UBE3A preferentially concentrates in euchromatin-rich domains within the nucleus. Electron microscopy reveals that labeling concentrates in the head and neck of dendritic spines and is excluded from the PSD. Strongest labeling within the neuropil was found in axon terminals. Conclusions By highlighting the subcellular compartments in which UBE3A is likely to function in the human neocortex, our data provide insight into the diverse functional capacities of this E3 ligase. These anatomical data may help to elucidate the role of UBE3A in Angelman syndrome and autism spectrum disorder

Implicit and explicit pedagogical practices related to sociocultural issues and social justice in physical education teacher education programs

Background: For many years, scholars in PETE have argued for the importance of educating pre-service teachers (PSTs) about equality (e.g., Evans 1990), sociocultural perspectives and issues (e.g., Cliff, Wright and Clarke, 2009; Author 2014) and critical pedagogy (e.g., Fernandez-Balboa 1997; Philpot 2015). Despite this advocacy, we would argue that there are significant differences in how faculty teach about sociocultural issues, and for, social justice. The pedagogical actions through which Physical Education Teacher Educators (PETEs) do this work is the focus of this paper. Purpose: We investigated the pedagogical approaches and strategies used by PETE faculty to address and educate PSTs about social justice and sociocultural issues related to gender, race, sexuality, (dis)ability, socioeconomic status and religion in their individual PETE programs. In this study, we draw on transformational pedagogy (Ukpokodu 2009; Ovens 2017) as a framework for theorizing the data. Through this study, we highlight the pedagogical practices espoused as those that engender transformative learning. Data collection and analysis: Data for this interpretive qualitative research study was collected primarily through in-depth semi-structured interviews with over 70 PETEs who work in 48 PETE programs across Australia, Canada, England, Ireland New Zealand, Sweden, and the United States. Furthermore, an informational survey was used to gather demographic data of the participants. The participants, all current PETEs, had a wide range of professional experiences, which included the length of time in the profession, the type of institution employed, educational backgrounds and courses taught. Data analysis was completed using the processes of content analysis and the constant comparative method (Corbin and Strauss 2008). Findings: Three major themes represent the findings. In the first theme, ‘Intentional and Explicit Pedagogies’ we provide descriptions of the approaches and strategies used by PETEs in this study that were planned in advance of the learning experiences. In the second theme, ‘Teachable Moments’ we provide examples of how PETEs utilized ‘teachable moments’ in implicit and explicit ways to educate PSTs about sociocultural issues. The third theme, ‘Resistance and Constraints’ captures the individual challenges PETE faculty faced within their courses if, and when, they teach for equity and social justice. The findings suggest that social justice struggles to find an explicit presence within many PETE programs and that educating PSTs about sociocultural issues and social justice is lacking in many PETE programs

NrCAM Deletion Causes Topographic Mistargeting of Thalamocortical Axons to the Visual Cortex and Disrupts Visual Acuity

NrCAM is a neural cell adhesion molecule of the L1 family that has been linked to autism spectrum disorders (ASDs), a disease spectrum in which abnormal thalamocortical connectivity may contribute to visual processing defects. Here we show that NrCAM interaction with Neuropilin-2 (Npn-2) is critical for Semaphorin3F (Sema3F)-induced guidance of thalamocortical axon subpopulations at the ventral telencephalon (VTe), an intermediate target for thalamic axon sorting. Genetic deletion of NrCAM or Npn-2 caused contingents of embryonic thalamic axons to misproject caudally in the VTe, away from a caudal-high Sema3F gradient. The resultant thalamocortical map of NrCAM null mutants showed striking mistargeting of motor and somatosensory thalamic axon contingents to the primary visual cortex, but retino-geniculate targeting and segregation were normal. NrCAM formed a molecular complex with Npn-2 in brain and neural cells, and was required for Sema3F-induced growth cone collapse in thalamic neuron cultures, consistent with a vital function for NrCAM in Sema3F-induced axon repulsion. NrCAM null mice displayed reduced responses to visual evoked potentials (VEPs) recorded from layer IV in the binocular zone of primary visual cortex (V1), particularly when evoked from the ipsilateral eye, indicating abnormal visual acuity and ocularity. These results demonstrate that NrCAM is required for normal maturation of cortical visual acuity, and suggest that the aberrant projection of thalamic motor and somatosensory axons to the visual cortex in NrCAM null mutant mice impairs cortical functions

Topoisomerases facilitate transcription of long genes linked to autism

Topoisomerases are expressed throughout the developing and adult brain and are mutated in some individuals with autism spectrum disorder (ASD). However, how topoisomerases are mechanistically connected to ASD is unknown. Here we found that topotecan, a Topoisomerase 1 (TOP1) inhibitor, dose-dependently reduced the expression of extremely long genes in mouse and human neurons, including nearly all genes >200 kb. Expression of long genes was also reduced following knockdown of Top1 or Top2b in neurons, highlighting that each enzyme was required for full expression of long genes. By mapping RNA polymerase II density genome-wide in neurons, we found that this length-dependent effect on gene expression was due to impaired transcription elongation. Interestingly, many high confidence ASD candidate genes are exceptionally long and were reduced in expression following TOP1 inhibition. Our findings suggest that chemicals and genetic mutations that impair topoisomerases could commonly contribute to ASD and other neurodevelopmental disorders

Reelin Secreted by GABAergic Neurons Regulates Glutamate Receptor Homeostasis

BACKGROUND: Reelin is a large secreted protein of the extracellular matrix that has been proposed to participate to the etiology of schizophrenia. During development, reelin is crucial for the correct cytoarchitecture of laminated brain structures and is produced by a subset of neurons named Cajal-Retzius. After birth, most of these cells degenerate and reelin expression persists in postnatal and adult brain. The phenotype of neurons that bind secreted reelin and whether the continuous secretion of reelin is required for physiological functions at postnatal stages remain unknown. METHODOLOGY/PRINCIPAL FINDINGS: Combining immunocytochemical and pharmacological approaches, we first report that two distinct patterns of reelin expression are present in cultured hippocampal neurons. We show that in hippocampal cultures, reelin is secreted by GABAergic neurons displaying an intense reelin immunoreactivity (IR). We demonstrate that secreted reelin binds to receptors of the lipoprotein family on neurons with a punctate reelin IR. Secondly, using calcium imaging techniques, we examined the physiological consequences of reelin secretion blockade. Blocking protein secretion rapidly and reversibly changes the subunit composition of N-methyl-D-aspartate glutamate receptors (NMDARs) to a predominance of NR2B-containing NMDARs. Addition of recombinant or endogenously secreted reelin rescues the effects of protein secretion blockade and reverts the fraction of NR2B-containing NMDARs to control levels. Therefore, the continuous secretion of reelin is necessary to control the subunit composition of NMDARs in hippocampal neurons. CONCLUSIONS/SIGNIFICANCE: Our data show that the heterogeneity of reelin immunoreactivity correlates with distinct functional populations: neurons synthesizing and secreting reelin and/or neurons binding reelin. Furthermore, we show that continuous reelin secretion is a strict requirement to maintain the composition of NMDARs. We propose that reelin is a trans-neuronal messenger secreted by GABAergic neurons that regulates NMDARs homeostasis in postnatal hippocampus. Defects in reelin secretion could play a major role in the development of neuropsychiatric disorders, particularly those associated with deregulation of NMDARs such as schizophrenia