Structure of native lens connexin 46/50 intercellular channels by cryo-EM.

Gap junctions establish direct pathways for cell-to-cell communication through the assembly of twelve connexin subunits that form intercellular channels connecting neighbouring cells. Co-assembly of different connexin isoforms produces channels with unique properties and enables communication across cell types. Here we used single-particle cryo-electron microscopy to investigate the structural basis of connexin co-assembly in native lens gap junction channels composed of connexin 46 and connexin 50 (Cx46/50). We provide the first comparative analysis to connexin 26 (Cx26), which-together with computational studies-elucidates key energetic features governing gap junction permselectivity. Cx46/50 adopts an open-state conformation that is distinct from the Cx26 crystal structure, yet it appears to be stabilized by a conserved set of hydrophobic anchoring residues. 'Hot spots' of genetic mutations linked to hereditary cataract formation map to the core structural-functional elements identified in Cx46/50, suggesting explanations for many of the disease-causing effects.

The Alcohol Sensitivity Questionnaire: Evidence for Construct Validity.

BACKGROUND: Variability in sensitivity to the acute effects of alcohol is an important risk factor for the development of alcohol use disorder (AUD). The most commonly used retrospective self-report measure of sensitivity, the Self-Rating of the Effects of Alcohol (SRE) form, queries a limited number of alcohol effects and relies on respondents' ability to recall experiences that might have occurred in the distant past. Here, we investigated the construct validity of an alternative measure that queries a larger number of alcohol effects, the Alcohol Sensitivity Questionnaire (ASQ), and compared it to the SRE in predicting momentary subjective responses to an acute dose of alcohol. METHODS: Healthy young adults (N = 423) completed the SRE and the ASQ and then were randomly assigned to consume either alcohol or a placebo beverage (between-subjects manipulation). Stimulation and sedation (Biphasic Alcohol Effects Scale) and subjective intoxication were measured multiple times after drinking. RESULTS: Hierarchical linear models showed that the ASQ reliably predicted each of these outcomes following alcohol but not placebo consumption, provided unique prediction beyond that associated with differences in recent alcohol involvement, and was preferred over the SRE (in terms of model fit) in direct model comparisons of stimulation and sedation. CONCLUSIONS: The ASQ compared favorably with the better-known SRE in predicting increased stimulation and reduced sedation following an acute alcohol challenge. The ASQ appears to be a valid self-report measure of alcohol sensitivity and therefore holds promise for identifying individuals at-risk for AUD and related problems.

The α-crystallin Chaperones Undergo a Quasi-ordered Co-aggregation Process in Response to Saturating Client Interaction.

Small heat shock proteins (sHSPs) are ATP-independent chaperones vital to cellular proteostasis, preventing protein aggregation events linked to various human diseases including cataract. The α-crystallins, αA-crystallin (αAc) and αB-crystallin (αBc), represent archetypal sHSPs that exhibit complex polydispersed oligomeric assemblies and rapid subunit exchange dynamics. Yet, our understanding of how this plasticity contributes to chaperone function remains poorly understood. Using biochemical and biophysical analyses combined with single-particle electron microscopy (EM), we examined structural changes in αAc, αBc and native heteromeric lens α-crystallins (αLc) in their apo-states and at varying degree of chaperone saturation leading to co-aggregation, using lysozyme and insulin as model clients. Quantitative single-particle analysis unveiled a continuous spectrum of oligomeric states formed during the co-aggregation process, marked by significant client-triggered expansion and quasi-ordered elongation of the sHSP oligomeric scaffold, whereby the native cage-like sHSP assembly displays a directional growth to accommodate saturating conditions of client sequestration. These structural modifications culminated in an apparent amorphous collapse of chaperone-client complexes, resulting in the creation of co-aggregates capable of scattering visible light. Intriguingly, these co-aggregates maintain internal morphological features of highly elongated sHSP oligomers with striking resemblance to polymeric α-crystallin species isolated from aged lens tissue. This mechanism appears consistent across αAc, αBc and αLc, albeit with varying degrees of susceptibility to client-induced co-aggregation. Importantly, our findings suggest that client-induced co-aggregation follows a distinctive mechanistic and quasi-ordered trajectory, distinct from a purely amorphous process. These insights reshape our understanding of the physiological and pathophysiological co-aggregation processes of α-crystallins, carrying potential implications for a pathway toward cataract formation.

The α-crystallin chaperones undergo a quasi-ordered co-aggregation process in response to saturating client interaction.

Small heat shock proteins (sHSPs) are ATP-independent chaperones vital to cellular proteostasis, preventing protein aggregation events linked to various human diseases including cataract. The α-crystallins, αA-crystallin (αAc) and αB-crystallin (αBc), represent archetypal sHSPs that exhibit complex polydispersed oligomeric assemblies and rapid subunit exchange dynamics. Yet, our understanding of how this plasticity contributes to chaperone function remains poorly understood. This study investigates structural changes in αAc and αBc during client sequestration under varying degree of chaperone saturation. Using biochemical and biophysical analyses combined with single-particle electron microscopy (EM), we examined αAc and αBc in their apo-states and at various stages of client-induced co-aggregation, using lysozyme as a model client. Quantitative single-particle analysis unveiled a continuous spectrum of oligomeric states formed during the co-aggregation process, marked by significant client-triggered expansion and quasi-ordered elongation of the sHSP scaffold. These structural modifications culminated in an apparent amorphous collapse of chaperone-client complexes, resulting in the creation of co-aggregates capable of scattering visible light. Intriguingly, these co-aggregates maintain internal morphological features of highly elongated sHSP scaffolding with striking resemblance to polymeric α-crystallin species isolated from aged lens tissue. This mechanism appears consistent across both αAc and αBc, albeit with varying degrees of susceptibility to client-induced co-aggregation. Importantly, our findings suggest that client-induced co-aggregation follows a distinctive mechanistic and quasi-ordered trajectory, distinct from a purely amorphous process. These insights reshape our understanding of the physiological and pathophysiological co-aggregation processes of sHSPs, carrying potential implications for a pathway toward cataract formation.

Treatment of Alcohol Use Problems Among Rural Populations: a Review of Barriers and Considerations for Increasing Access to Quality Care.

Purpose of Review: Individuals living in rural areas face unique challenges when accessing services for alcohol-related problems and are at increased risk of experiencing alcohol-related harms. We outline research on rural-urban treatment gaps in alcohol use treatment, identify common barriers to treatment, and provide recommendations for how to address the difficulties faced by this population. Recent Findings: Globally, individuals living in rural and remote areas are less likely to receive care for alcohol-related concerns compared to those residing in urban areas. Rural areas suffer from insufficient access to specialty providers, and rural residents are likely to experience greater stigma regarding seeking treatment for alcohol-related concerns. Summary: Given rural-urban disparities in access to treatment for alcohol use concerns, treatment efforts should incorporate stakeholders across the medical system. Telehealth options are particularly promising for increasing access to care. Adaptations should emphasize existing strengths among rural populations, such as strong religious beliefs and close community ties.

Beyond BASICS: A scoping review of novel intervention content to enhance the efficacy of brief alcohol interventions for emerging adults.

OBJECTIVE: Brief motivational interventions (BMIs) that include personalized drinking feedback delivered in a motivational interviewing (MI) style have demonstrated reductions in drinking across numerous clinical trials with emerging adults (EAs) ages 18-25. However, effect sizes for these BMIs are generally small to moderate and drinking reductions are often not maintained beyond short-term follow-ups. Additionally, EAs may be more interested in approaches that highlight wellness, mood enhancement, or goal pursuit rather than programs focused exclusively on reducing alcohol-related risk. Thus, there is a need to evaluate novel intervention content as an alternative or supplement to BMIs in this high-risk population. METHOD: This scoping review examined studies of novel intervention elements to reduce alcohol consumption among EAs. Eligible studies were published in peer-reviewed journals in English from January 2015 to September 2021 and evaluated novel brief interventions, operationalized as one to five sessions focused on alcohol-related outcomes with key content beyond what has typically been included in alcohol BMIs. Results were categorized as additions to BMIs or stand-alone interventions and were synthesized within these categories by theoretical approach. RESULTS: Although standard in-person BMIs have the greatest empirical support, there are a variety of alternative intervention approaches that might enhance health and wellness and that can be feasibly integrated with BMIs or offered as an appealing "gateway" to increase help-seeking among EAs who drink alcohol. CONCLUSIONS: More research is needed to empirically evaluate both the relative efficacy of supplements and stand-alone alternatives to BMI among higher risk EAs and their potential for widespread dissemination. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Characterizing alcohol dependence: transitions during young and middle adulthood.

Community and high-risk sample studies suggest that alcohol dependence is relatively stable and chronic. By contrast, epidemiological studies demonstrate a strong age-graded decline whereby alcohol dependence tends to peak in early adulthood and declines thereafter. The authors identified the latent trajectory structure of past-year alcohol dependence to investigate (a) whether the syndrome is characterized by symptom profiles and (b) the extent to which the syndrome is stable and persistent. Data from current drinkers (N = 4,003) in the National Longitudinal Survey of Youth were analyzed across two waves: 1989 (ages 24-32 years) and 1994 (ages 29-37 years). Three classes of alcohol dependence were observed; symptom endorsement probabilities increased across successively severe classes. Latent transition analyses showed high rates of stability, supporting alcohol dependence as a relatively chronic condition. Although there was evidence of progression to more severe dependence, there was greater syndrome remission. Trajectory classes and transition probabilities were generalizable across race and sex and, to a lesser extent, age cohort and family history of alcoholism.

Reliability of self-reported age of substance involvement onset.

The authors investigated the reliability of self-reported age of onset (AO) for alcohol, tobacco (cigarette), and illicit drug involvement. Participants were 410 young adults taking part in an 11-year longitudinal study. A moderate degree of reliability was found for the 3 substances. Despite this level of stability, results illustrate a tendency for reported AOs to increase over time. The trend is more salient for participants who reported younger AOs at the initial assessment. Findings also indicate that, for alcohol and tobacco, more individuals were classified as early onset based on Year 1 compared with Year 11 reports. Despite these systematic changes, at least for alcohol and illicit drugs, age at which onset was assessed did not moderate the association between AO and substance-related outcomes.

Dimensionality of alcohol dependence in young adulthood: current versus lifetime symptomatology.

OBJECTIVE: The factor structure of alcohol dependence was investigated using exploratory factor analysis, specifically contrasting models of alcohol dependence based on lifetime symptom endorsement to models based on current (i.e., past-year) symptom endorsement. METHOD: Data from the 1989 National Longitudinal Survey of Youth were analyzed. DSM-IV alcohol dependence was assessed in this large community sample of current drinkers and lifetime drinkers, representative of both men and women, and ranging in age from 24 to 32. Sixteen items assessing the seven criteria of DSM-IV alcohol dependence were employed. RESULTS: A single-factor model accounted for most of the observed relationships. However, evidence of additional dimensions, characterized by tolerance and impaired control symptoms, was also identified. CONCLUSIONS: Our findings do not support the historical tendency of distinguishing physiological (as indicated by tolerance or withdrawal symptoms) from nonphysiological dependence. Most importantly, factor solutions derived from items based on past-year symptom endorsement were consistent with those derived from items based on lifetime symptom endorsement in samples of both current drinkers and lifetime drinkers.

AKAP2 anchors PKA with aquaporin-0 to support ocular lens transparency.

A decline in ocular lens transparency known as cataract afflicts 90% of individuals by the age 70. Chronic deterioration of lens tissue occurs as a pathophysiological consequence of defective water and nutrient circulation through channel and transporter proteins. A key component is the aquaporin-0 (AQP0) water channel whose permeability is tightly regulated in healthy lenses. Using a variety of cellular and biochemical approaches we have discovered that products of the A-kinase anchoring protein 2 gene (AKAP2/AKAP-KL) form a stable complex with AQP0 to sequester protein kinase A (PKA) with the channel. This permits PKA phosphorylation of serine 235 within a calmodulin (CaM)-binding domain of AQP0. The additional negative charge introduced by phosphoserine 235 perturbs electrostatic interactions between AQP0 and CaM to favour water influx through the channel. In isolated mouse lenses, displacement of PKA from the AKAP2-AQP0 channel complex promotes cortical cataracts as characterized by severe opacities and cellular damage. Thus, anchored PKA modulation of AQP0 is a homeostatic mechanism that must be physically intact to preserve lens transparency.