Structural insights into GrpEL1-mediated nucleotide and substrate release of human mitochondrial Hsp70.

Maintenance of protein homeostasis is necessary for cell viability and depends on a complex network of chaperones and co-chaperones, including the heat-shock protein 70 (Hsp70) system. In human mitochondria, mitochondrial Hsp70 (mortalin) and the nucleotide exchange factor (GrpEL1) work synergistically to stabilize proteins, assemble protein complexes, and facilitate protein import. However, our understanding of the molecular mechanisms guiding these processes is hampered by limited structural information. To elucidate these mechanistic details, we used cryoEM to determine the first structures of full-length human mortalin-GrpEL1 complexes in previously unobserved states. Our structures and molecular dynamics simulations allow us to delineate specific roles for mortalin-GrpEL1 interfaces and to identify steps in GrpEL1-mediated nucleotide and substrate release by mortalin. Subsequent analyses reveal conserved mechanisms across bacteria and mammals and facilitate a complete understanding of sequential nucleotide and substrate release for the Hsp70 chaperone system.

Tuning ice thickness using the chameleon for high-quality cryoEM data collection.

Advances in single-particle cryogenic electron microscopy (cryoEM) now allow for routine structure determination of well-behaved biological specimens to high-resolution. Despite advances in the electron microscope, direct electron detectors, and data processing software, the preparation of high-quality grids with thin layers of vitreous ice containing the specimen of interest in random orientations remains a critical bottleneck for many projects. Although numerous efforts have been dedicated to overcoming hurdles frequently encountered during specimen vitrification using traditional blot-and-plunge specimen preparation techniques, the development of blot-free grid preparation devices provide a unique opportunity to carefully tune ice thickness, particle density, and specimen behavior during the vitrification process for improvements in image quality. Here, we describe critical steps of high-quality grid preparation using a SPT Labtech chameleon, evaluation of grid quality/ice thickness using the chameleon software, high-throughput imaging in the electron microscope, and recommend steps for troubleshooting grid preparation when standard parameters fail to yield suitable specimen.

Visual association cortex links cues with conjunctions of reward and locomotor contexts.

Postrhinal cortex (POR) and neighboring lateral visual association areas are necessary for identifying objects and interpreting them in specific contexts, but how POR neurons encode the same object across contexts remains unclear. Here, we imaged excitatory neurons in mouse POR across tens of days prior to and throughout initial cue-reward learning and reversal learning. We assessed responses to the same cue when it was rewarded or unrewarded, during both locomotor and stationary contexts. Surprisingly, a large class of POR neurons were minimally cue-driven prior to learning. After learning, distinct clusters within this class responded selectively to a given cue when presented in a specific conjunction of reward and locomotion contexts. In addition, another class contained clusters of neurons whose cue responses were more transient, insensitive to reward learning, and adapted over thousands of presentations. These two classes of POR neurons may support context-dependent interpretation and context-independent identification of sensory cues.

Manual Blot-and-Plunge Freezing of Biological Specimens for Single-Particle Cryogenic Electron Microscopy.

Imaging biological specimens with electrons for high-resolution structure determination by single-particle cryogenic electron microscopy (cryoEM) requires a thin layer of vitreous ice containing the biomolecules of interest. Despite numerous technological advances in recent years that have propelled single-particle cryoEM to the forefront of structural biology, the methods by which specimens are vitrified for high-resolution imaging often remain the rate-limiting step. Although numerous recent efforts have provided means to overcome hurdles frequently encountered during specimen vitrification, including the development of novel sample supports and innovative vitrification instrumentation, the traditional manually operated plunger remains a staple in the cryoEM community due to the low cost to purchase and ease of operation. Here, we provide detailed methods for using a standard, guillotine-style manually operated blot-and-plunge device for the vitrification of biological specimens for high-resolution imaging by single-particle cryoEM. Additionally, commonly encountered issues and troubleshooting recommendations for when a standard preparation fails to yield a suitable specimen are also described.

4-Oxooctahydroquinoline-1(2H)-carboxamides as hepatitis B virus (HBV) capsid core protein assembly modulators.

Hepatitis B virus (HBV) core protein, the building block of the HBV capsid, plays multiple roles in viral replication, and is an attractive target for development of antiviral agents with a new mechanism of action. In addition to the heteroaryldihydropyrimidines (HAPs), sulfamoylbenzamides (SBAs), dibenzothiazepine derivatives (DBTs), and sulfamoylpyrrolamides (SPAs) that inhibit HBV replication by modulation of viral capsid assembly and are currently under clinical trials for the treatment of chronic hepatitis B (CHB), other chemical structures with activity to modulate HBV capsid assembly have also been explored. Here we describe our continued optimization of a benzamide originating from our high throughput screening. A new bicyclic carboxamide lead featuring an electron deficient non-planar core structure was discovered. Evaluations of its ADMET (absorption, distribution, metabolism, excretion and toxicity) and pharmacokinetic (PK) profiles demonstrate improved metabolic stability and good bioavailability.

COVID-19, Contagion, and Vaccine Optimism.

Steven Soderbergh's Contagion (2011) positions the vaccine as the end point of the arc of â€‹pandemic, marking both the containment of an elusive virus and â€‹the resumption of a life not fundamentally different from â€‹before the disease outbreak. ​The film reinforces the â€‹assumption that a pandemic will awaken â€‹all of us to the urgency of vaccination​, persuading us to put aside our reservations and anxieties â€‹and the idea that compliance is the inevitable outcome of quarantine. This article explores how pro-vaccination cultural products â€‹such as Contagion might in fact undermine public health efforts by promoting a false narrative, which simplifies the kind of vaccination campaign necessary for herd immunity to develop. An ethic of sacrifice and selflessness drives the public health messaging of the film but leaves intact certain individualistic tropes and plague narrative scapegoating tendencies, while the framing of the vaccine as "gift" takes it out of the realm of medical science altogether.

Mechanism and Kinetics of Copper Complexes Binding to the Influenza A M2 S31N and S31N/G34E Channels.

Copper(II) is known to bind in the influenza virus His37 cluster in the homotetrameric M2 proton channel and block the proton current needed for uncoating. Copper complexes based on iminodiacetate also block the M2 proton channel and show reduced cytotoxicity and zebrafish-embryo toxicity. In voltage-clamp oocyte studies using the ubiquitous amantadine-insensitive M2 S31N variant, the current block showed fast and slow phases, in contrast to the single phase found for amantadine block of wild-type M2. Here, we evaluate the mechanism of block by copper adamantyl iminodiacitate and copper cyclooctyl iminodiacitate complexes and address whether the complexes can coordinate with one or more of the His37 imidazoles. The current traces were fitted to parametrized master equations. The energetics of binding and the rate constants suggest that the first step is copper complex binding within the channel, and the slow step in the current block is the formation of a Cu-histidine coordination complex. Solution-phase isothermal titration calorimetry and density functional theory (DFT) calculations indicate that imidazole binds to the copper complexes. Structural optimization using DFT reveals that the complexes fit inside the channel and project the Cu(II) toward the His37 cluster, allowing one imidazole to form a coordination complex with Cu(II). Electrophysiology and DFT studies also show that the complexes block the G34E amantadine-resistant mutant despite some crowding in the binding site by the glutamates.

Increased Dissociation of Adamantanamines in Influenza A M2 S31N with Partial Block by Rimantadine.

The ubiquitous mutation from serine (WT) to asparagine at residue 31 (S31N) in the influenza A M2 channel renders it insensitive to amantadine (AMT) and rimantadine (RMT) block, but it is unknown whether the inhibition results from weak binding or incomplete block. Two-electrode voltage clamp (TEVC) of transfected Xenopus oocytes revealed that the M2 S31N channel is essentially fully blocked by AMT at 10 mM, demonstrating that, albeit weak, AMT binding in a channel results in complete block of its proton current. In contrast, RMT achieves only a modest degree of block in the M2 S31N channel at 1 mM, with very little increase in block at 10 mM, indicating that the RMT binding site in the channel saturates with only modest block. From exponential curve fits to families of proton current wash-in and wash-out traces, the association rate constant (k1) is somewhat decreased for both AMT and RMT in the S31N, but the dissociation rate constant (k2) is dramatically increased compared with WT. The potentials of mean force (PMF) from adaptive biasing force (ABF) molecular dynamics simulations predict that rate constants should be exquisitely sensitive to the charge state of the His37 selectivity filter of M2. With one exception out of eight cases, predictions from the simulations with one and three charged side chains bracket the experimental rate constants, as expected for the acidic bath used in the TEVC assay. From simulations, the weak binding can be accounted for by changes in the potentials of mean force, but the partial block by RMT remains unexplained.

Chemical Probes for Blocking of Influenza A M2 Wild-type and S31N Channels.

We report on using the synthetic aminoadamantane-CH2-aryl derivatives 1-6 as sensitive probes for blocking M2 S31N and influenza A virus (IAV) M2 wild-type (WT) channels as well as virus replication in cell culture. The binding kinetics measured using electrophysiology (EP) for M2 S31N channel are very dependent on the length between the adamantane moiety and the first ring of the aryl headgroup realized in 2 and 3 and the girth and length of the adamantane adduct realized in 4 and 5. Study of 1-6 shows that, according to molecular dynamics (MD) simulations and molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) calculations, all bind in the M2 S31N channel with the adamantyl group positioned between V27 and G34 and the aryl group projecting out of the channel with the phenyl (or isoxazole in 6) embedded in the V27 cluster. In this outward binding configuration, an elongation of the ligand by only one methylene in rimantadine 2 or using diamantane or triamantane instead of adamantane in 4 and 5, respectively, causes incomplete entry and facilitates exit, abolishing effective block compared to the amantadine derivatives 1 and 6. In the active M2 S31N blockers 1 and 6, the phenyl and isoxazolyl head groups achieve a deeper binding position and high kon/low koff and high kon/high koff rate constants, compared to inactive 2-5, which have much lower kon and higher koff. Compounds 1-5 block the M2 WT channel by binding in the longer area from V27-H37, in the inward orientation, with high kon and low koff rate constants. Infection of cell cultures by influenza virus containing M2 WT or M2 S31N is inhibited by 1-5 or 1-4 and 6, respectively. While 1 and 6 block infection through the M2 block mechanism in the S31N variant, 2-4 may block M2 S31N virus replication in cell culture through the lysosomotropic effect, just as chloroquine is thought to inhibit SARS-CoV-2 infection.

Editorial: Important First Look at Population-Based Trajectories of Youths With Autism.

Few studies have followed young people with autism spectrum disorder (shortened to "autism" herein) over time, and all previous longitudinal studies have used clinical or center-based samples,1,2 leaving considerable uncertainty about the course of autism in the general population. In this issue, Simonoff and colleagues3 describe the first longitudinal study within a population-based sample, the Special Needs and Autism Project (SNAP) cohort. By assessing adolescents and young adults with autism at 3 time points over 11 years, from approximately 12 to 23 years of age, the authors profiled the trajectories of both cognitive and autism symptoms. Despite little change in caregiver-rated autism symptoms over this time period, they found that full-scale IQ (FSIQ) showed a moderate increase, with some hints of factors that may predict greater improvement.

Cortical reactivations of recent sensory experiences predict bidirectional network changes during learning.

Salient experiences are often relived in the mind. Human neuroimaging studies suggest that such experiences drive activity patterns in visual association cortex that are subsequently reactivated during quiet waking. Nevertheless, the circuit-level consequences of such reactivations remain unclear. Here, we imaged hundreds of neurons in visual association cortex across days as mice learned a visual discrimination task. Distinct patterns of neurons were activated by different visual cues. These same patterns were subsequently reactivated during quiet waking in darkness, with higher reactivation rates during early learning and for food-predicting versus neutral cues. Reactivations involving ensembles of neurons encoding both the food cue and the reward predicted strengthening of next-day functional connectivity of participating neurons, while the converse was observed for reactivations involving ensembles encoding only the food cue. We propose that task-relevant neurons strengthen while task-irrelevant neurons weaken their dialog with the network via participation in distinct flavors of reactivation.

Practice Parameter for the Assessment and Treatment of Psychiatric Disorders in Children and Adolescents With Intellectual Disability (Intellectual Developmental Disorder).

Intellectual disability (intellectual developmental disorder) (ID/IDD) is both a psychiatric disorder and a risk factor for co-occurring psychiatric disorders in children and adolescents. DSM-5 introduced important changes in the conceptualization and diagnosis of ID/IDD, and current research studies clarify assessment and treatment of co-occurring psychiatric disorders in this population. Optimal assessment and treatment of psychiatric illness in children and adolescents with ID/IDD includes modifications in diagnostic and treatment techniques, appreciation of variations in the clinical presentation of psychiatric disorders, an understanding of the spectrum of etiologies of behavioral disturbance, and knowledge of psychosocial and medical interventions.

Overemphasis of the Autism Diagnostic Observation Schedule (ADOS) Evaluation Subverts a Clinician's Ability to Provide Access to Autism Services.

A concerning trend has emerged in the diagnosis and treatment of autism spectrum disorder (ASD) that has a negative impact on care. Quite often, a clinician's diagnosis of ASD using DSM-5 criteria is no longer sufficient for individuals with ASD to access services. Insurance companies, school districts, and developmental disability agencies commonly require an Autism Diagnostic Observation Schedule (ADOS) to be eligible for services.

Unraveling the Binding, Proton Blockage, and Inhibition of Influenza M2 WT and S31N by Rimantadine Variants.

Recently, the binding kinetics of a ligand-target interaction, such as the residence time of a small molecule on its protein target, are seen as increasingly important for drug efficacy. Here, we investigate these concepts to explain binding and proton blockage of rimantadine variants bearing progressively larger alkyl groups to influenza A virus M2 wild type (WT) and M2 S31N protein proton channel. We showed that resistance of M2 S31N to rimantadine analogues compared to M2 WT resulted from their higher koff rates compared to the kon rates according to electrophysiology (EP) measurements. This is due to the fact that, in M2 S31N, the loss of the V27 pocket for the adamantyl cage resulted in low residence time inside the M2 pore. Both rimantadine enantiomers have similar channel blockage and binding kon and koff against M2 WT. To compare the potency between the rimantadine variants against M2, we applied approaches using different mimicry of M2, i.e., isothermal titration calorimetry and molecular dynamics simulation, EP, and antiviral assays. It was also shown that a small change in an amino acid at site 28 of M2 WT, which does not line the pore, seriously affects M2 WT blockage kinetics.

Psychiatric hospital treatment of youth with autism spectrum disorder in the United States: needs, outcomes, and policy.

Children with Autism Spectrum Disorder (ASD) are admitted to inpatient psychiatric units at markedly high rates. As health insurance companies and government healthcare systems and regulators seek more evidence for healthcare outcomes, it is important to learn more about the effectiveness of psychiatric inpatient admissions for children with ASD to best inform decisions on provision and access to this level of care. Evidence for models of inpatient treatment for youth with ASD is presented, and key characteristics and consensus recommendations for care are discussed.

Divalent copper complexes as influenza A M2 inhibitors.

New M2 blockers effective against the ubiquitous amantadine-resistant S31N M2 mutation in influenza A are needed. Six copper complexes, 2, 4, 6, 8, 9, and 10, were synthesized and found to block both wild type and S31N M2. Free Cu2+ also blocks M2 S31N but not S31N/H37A. The copper complexes do not block M2 H37A (either S31 or S31N). The complexes were effective against three influenza A strains in cell-culture assays, but less toxic to cells than CuCl2. For example 4, Cu(cyclooctylamineiminodiacetate), which was stable at pH > 4 in the buffers used, had an EC50 against A/Calif/07/2009 H1N1 of 0.7 ± 0.1 µM with a CC50 of 147 µM (therapeutic index, averaged over three strains, 67.8). In contrast, CuCl2 had an EC50 of 3.8 ± 0.9 µM and CC50 of 19 µM. Because M2 H37 is highly conserved, these complexes show promise for further testing as drugs against all strains of influenza A.

Rapid Molecular Profiling of Defined Cell Types Using Viral TRAP.

Translational profiling methodologies enable the systematic characterization of cell types in complex tissues, such as the mammalian brain, where neuronal isolation is exceptionally difficult. Here, we report a versatile strategy for profiling CNS cell types in a spatiotemporally restricted fashion by engineering a Cre-dependent adeno-associated virus expressing an EGFP-tagged ribosomal protein (AAV-FLEX-EGFPL10a) to access translating mRNAs by translating ribosome affinity purification (TRAP). We demonstrate the utility of this AAV to target a variety of genetically and anatomically defined neural populations expressing Cre recombinase and illustrate the ability of this viral TRAP (vTRAP) approach to recapitulate the molecular profiles obtained by bacTRAP in corticothalamic neurons across multiple serotypes. Furthermore, spatially restricting adeno-associated virus (AAV) injections enabled the elucidation of regional differences in gene expression within this cell type. Altogether, these results establish the broad applicability of the vTRAP strategy for the molecular dissection of any CNS or peripheral cell type that can be engineered to express Cre.

Measuring Changes in Social Communication Behaviors: Preliminary Development of the Brief Observation of Social Communication Change (BOSCC).

Psychometric properties and initial validity of the Brief Observation of Social Communication Change (BOSCC), a measure of treatment-response for social-communication behaviors, are described. The BOSCC coding scheme is applied to 177 video observations of 56 young children with ASD and minimal language abilities. The BOSCC has high to excellent inter-rater and test-retest reliability and shows convergent validity with measures of language and communication skills. The BOSCC Core total demonstrates statistically significant amounts of change over time compared to a no change alternative while the ADOS CSS over the same period of time did not. This work is a first step in the development of a novel outcome measure for social-communication behaviors with applications to clinical trials and longitudinal studies.

Irritability and Problem Behavior in Autism Spectrum Disorder: A Practice Pathway for Pediatric Primary Care.

OBJECTIVE: Pediatric primary care providers (PCPs) caring for patients with autism spectrum disorder (ASD) often encounter irritability (vocal or motoric outbursts expressive of anger, frustration, or distress) and problem behavior (directed acts of aggression toward other people, self, or property). The Autism Intervention Research Network on Physical Health and Autism Speaks Autism Treatment Network charged a multidisciplinary workgroup with developing a practice pathway to assist PCPs in the evaluation and treatment of irritability and problem behavior (I/PB). METHODS: The workgroup reviewed the literature on the evaluation and treatment of contributory factors for I/PB in ASD. The workgroup then achieved consensus on the content and sequence of each step in the pathway. RESULTS: The practice pathway is designed to help the PCP generate individualized treatment plans based on contributing factors identified in each patient. These factors may include medical conditions, which the PCP is in a key position to address; functional communication challenges that can be addressed at school or at home; psychosocial stressors that may be ameliorated; inadvertent reinforcement of I/PB; and co-occurring psychiatric conditions that can be treated. The pathway provides guidance on psychotropic medication use, when indicated, within an individualized treatment plan. In addition to guidance on assessment, referral, and initial treatment, the pathway includes monitoring of treatment response and periodic reassessment. CONCLUSIONS: The pediatric PCP caring for the patient with ASD is in a unique position to help generate an individualized treatment plan that targets factors contributing to I/PB and to implement this plan in collaboration with parents, schools, and other providers.