Rare coding variants in CHRNB2 reduce the likelihood of smoking.

Human genetic studies of smoking behavior have been thus far largely limited to common variants. Studying rare coding variants has the potential to identify drug targets. We performed an exome-wide association study of smoking phenotypes in up to 749,459 individuals and discovered a protective association in CHRNB2, encoding the ß2 subunit of the α4ß2 nicotine acetylcholine receptor. Rare predicted loss-of-function and likely deleterious missense variants in CHRNB2 in aggregate were associated with a 35% decreased odds for smoking heavily (odds ratio (OR) = 0.65, confidence interval (CI) = 0.56-0.76, P = 1.9 × 10-8). An independent common variant association in the protective direction ( rs2072659 ; OR = 0.96; CI = 0.94-0.98; P = 5.3 × 10-6) was also evident, suggesting an allelic series. Our findings in humans align with decades-old experimental observations in mice that ß2 loss abolishes nicotine-mediated neuronal responses and attenuates nicotine self-administration. Our genetic discovery will inspire future drug designs targeting CHRNB2 in the brain for the treatment of nicotine addiction.

In the midst of the perfect storm: Swift public health actions needed in order to increase societal safety during the COVID-19 pandemic.

The phenomenal speed of COVID-19 has subjected the public health professionals worldwide to struggle to subdue the spread of the disease and its impact of the affected societies. The limited biomedical and epidemiological understanding of COVID-19 along with the lack of vaccines and therapeutics have led to the reception of draconian measures from the societal safety domain, limiting human interaction through social distancing. Grounded on the adopted approaches, interventions in sero-prevalence studies, mobilisation of the primary health care (PHC) sector, as well as target socially vulnerable groups should be taken into consideration by heath authorities.

The antibody rHIgM22 facilitates hippocampal remyelination and ameliorates memory deficits in the cuprizone mouse model of demyelination.

Multiple sclerosis (MS) is a chronic, inflammatory demyelinating disease of the CNS. In addition to motor, sensory and visual deficits, MS is also characterized by hippocampal demyelination and memory impairment. We recently demonstrated that a recombinant human-derived monoclonal IgM antibody, which is designated rHIgM22 and currently in clinical development for people with MS, accelerates remyelination of the corpus callosum in the brains of cuprizone-treated mice. Here, we investigated the effects of rHIgM22 in the hippocampus and on hippocampal-dependent learning and memory in the same mouse model of cuprizone-induced demyelination and spontaneous remyelination. The degree of hippocampal myelination of cuprizone-fed mice treated with a single dose of rHIgM22 (10 mg/kg of body weight) was examined immediately after the end of the cuprizone diet as well as at different time points during the recovery period with regular food, and compared with that of cuprizone-fed animals treated with either vehicle or human IgM isotype control antibody. Mice fed only regular food were used as controls. Four or five mice per treatment group were examined for each time point. We demonstrate that treatment with rHIgM22 accelerated remyelination of the demyelinated hippocampus. Using two additional cohorts of mice and eight animals per treatment group for each cohort, we also demonstrate that the enhancing effects of rHIgM22 on hippocampal remyelination were accompanied by improved performance in the Morris water maze and amelioration of the memory deficits induced by cuprizone. These results further confirm the remyelination-promoting capabilities of rHIgM22 and support additional investigation of its therapeutic potential in MS.

rHIgM22 enhances remyelination in the brain of the cuprizone mouse model of demyelination.

Failure of oligodendrocyte precursor cells (OPCs) to differentiate and remyelinate axons is thought to be a major cause of the limited ability of the central nervous system to repair plaques of immune-mediated demyelination in multiple sclerosis (MS). Current therapies for MS aim to lessen the immune response in order to reduce the frequency and severity of attacks, but these existing therapies do not target remyelination or stimulate repair of the damaged tissue. Thus, the promotion of OPC differentiation and remyelination is potentially an important therapeutic goal. Previous studies have shown that a recombinant human-derived monoclonal IgM antibody, designated rHIgM22, promotes remyelination, particularly of the spinal cord in rodent models of demyelination. Here, we examined the effects of rHIgM22 in remyelination in the brain using the mouse model of cuprizone-induced demyelination, which is characterized by spontaneous remyelination. The myelination state of the corpus callosum of cuprizone-fed mice treated with rHIgM22 was examined immediately after the end of the cuprizone diet as well as at different time points during the recovery period with regular food, and compared with that of cuprizone-fed animals treated with either vehicle or human IgM isotype control antibody. Mice fed only regular food were used as controls. We demonstrate that treatment with rHIgM22 accelerated remyelination of the demyelinated corpus callosum. The remyelination-enhancing effects of rHIgM22 were found across different, anatomically distinct regions of the corpus callosum, and followed a spatiotemporal pattern that was similar to that of the spontaneous remyelination process. These enhancing effects were also accompanied by increased differentiation of OPCs into mature oligodendrocytes. Our data indicate strong remyelination-promoting capabilities of rHIgM22 and further support its therapeutic potential in MS.

An optimized dosing regimen of cimaglermin (neuregulin 1ß3, glial growth factor 2) enhances molecular markers of neuroplasticity and functional recovery after permanent ischemic stroke in rats.

Cimaglermin (neuregulin 1ß3, glial growth factor 2) is a neuregulin growth factor family member in clinical development for chronic heart failure. Previously, in a permanent middle cerebral artery occlusion (pMCAO) rat stroke model, systemic cimaglermin treatment initiated up to 7 days after ischemia onset promoted recovery without reduced lesion volume. Presented here to extend the evidence are two studies that use a rat stroke model to evaluate the effects of cimaglermin dose level and dose frequency initiated 24 hr after pMCAO. Forelimb- and hindlimb-placing scores (proprioceptive behavioral tests), body-swing symmetry, and infarct volume were compared between treatment groups (n = 12/group). Possible mechanisms underlying cimaglermin-mediated neurologic recovery were examined through axonal growth and synapse formation histological markers. Cimaglermin was evaluated over a wider dose range (0.02, 0.1, or 1.0 mg/kg) than doses previously shown to be effective but used the same dosing regimen (2 weeks of daily intravenous administration, then 1 week without treatment). The dose-frequency study used the dose-ranging study's most effective dose (1.0 mg/kg) to compare daily, once per week, and twice per week dosing for 3 weeks (then 1 week without treatment). Dose- and frequency-dependent functional improvements were observed with cimaglermin without reduced lesion volume. Cimaglermin treatment significantly increased growth-associated protein 43 expression in both hemispheres (particularly somatosensory and motor cortices) and also increased synaptophysin expression. These data indicate that cimaglermin enhances recovery after stroke. Immunohistochemical changes were consistent with axonal sprouting and synapse formation but not acute neuroprotection. Cimaglermin represents a potential clinical development candidate for ischemic stroke treatment.

The Persistence of Hippocampal-Based Memory Requires Protein Synthesis Mediated by the Prion-like Protein CPEB3.

Consolidation of long-term memories depends on de novo protein synthesis. Several translational regulators have been identified, and their contribution to the formation of memory has been assessed in the mouse hippocampus. None of them, however, has been implicated in the persistence of memory. Although persistence is a key feature of long-term memory, how this occurs, despite the rapid turnover of its molecular substrates, is poorly understood. Here we find that both memory storage and its underlying synaptic plasticity are mediated by the increase in level and in the aggregation of the prion-like translational regulator CPEB3 (cytoplasmic polyadenylation element-binding protein). Genetic ablation of CPEB3 impairs the maintenance of both hippocampal long-term potentiation and hippocampus-dependent spatial memory. We propose a model whereby persistence of long-term memory results from the assembly of CPEB3 into aggregates. These aggregates serve as functional prions and regulate local protein synthesis necessary for the maintenance of long-term memory.

Implementation and Operational Research: Barriers and Facilitators to Combined ART Initiation in Pregnant Women With HIV: Lessons Learnt From a PMTCT B+ Pilot Program in Swaziland.

BACKGROUND: In January 2013, Swaziland launched a prevention of mother-to-child transmission of HIV (PMTCT) B+ implementation study in rural Shiselweni. We aimed to identify patient and health service determinants of combined antiretroviral therapy (ART) initiation to help guide national implementation of PMTCT B+. METHODS: This prospective cohort study uses routine data from registers and patient files in the PMTCT B+ pilot zone and a neighboring health zone where PMTCT A was the standard of care. All HIV-positive women not on combined ART at the first antenatal care visit between January 28, 2013 and December 31, 2013 were included. RESULTS: 399 women from the PMTCT B+ zone and 183 from the PMTCT A zone are included. The overall proportion of women who had not started an antiretroviral intervention before 32 weeks' gestation was lower in the PMTCT A zone (13% vs 25%, P = 0.003), yet a higher proportion women with CD4 <350 initiated combined ART in the PMTCT B+ zone (86% vs 74%, P = 0.032). Within the PMTCT B+ pilot, initiation rates were highly variable between health facilities; while at patient level, ART initiation was significantly higher among women with CD4 <350 compared with CD4 >350 (80% vs 59%, P < 0.001). Among women with CD4 <350, those recorded as newly diagnosed were more likely to initiate combined ART. Although lower educational level and occupational barriers seemed to hinder combined ART initiation among women with CD4 >350, high proportions of missing socio-demographic data made it impossible to make any firm conclusions to this respect. CONCLUSIONS: This study not only demonstrates challenges in initiating pregnant women on ART, but also identifies opportunities offered by PMTCT B+ for improving treatment initiation among women with lower CD4 counts.

Molecular mechanism for age-related memory loss: the histone-binding protein RbAp48.

To distinguish age-related memory loss more explicitly from Alzheimer's disease (AD), we have explored its molecular underpinning in the dentate gyrus (DG), a subregion of the hippocampal formation thought to be targeted by aging. We carried out a gene expression study in human postmortem tissue harvested from both DG and entorhinal cortex (EC), a neighboring subregion unaffected by aging and known to be the site of onset of AD. Using expression in the EC for normalization, we identified 17 genes that manifested reliable age-related changes in the DG. The most significant change was an age-related decline in RbAp48, a histone-binding protein that modifies histone acetylation. To test whether the RbAp48 decline could be responsible for age-related memory loss, we turned to mice and found that, consistent with humans, RbAp48 was less abundant in the DG of old than in young mice. We next generated a transgenic mouse that expressed a dominant-negative inhibitor of RbAp48 in the adult forebrain. Inhibition of RbAp48 in young mice caused hippocampus-dependent memory deficits similar to those associated with aging, as measured by novel object recognition and Morris water maze tests. Functional magnetic resonance imaging studies showed that within the hippocampal formation, dysfunction was selectively observed in the DG, and this corresponded to a regionally selective decrease in histone acetylation. Up-regulation of RbAp48 in the DG of aged wild-type mice ameliorated age-related hippocampus-based memory loss and age-related abnormalities in histone acetylation. Together, these findings show that the DG is a hippocampal subregion targeted by aging, and identify molecular mechanisms of cognitive aging that could serve as valid targets for therapeutic intervention.

Neuralized1 activates CPEB3: a function for nonproteolytic ubiquitin in synaptic plasticity and memory storage.

The cytoplasmic polyadenylation element-binding protein 3 (CPEB3), a regulator of local protein synthesis, is the mouse homolog of ApCPEB, a functional prion protein in Aplysia. Here, we provide evidence that CPEB3 is activated by Neuralized1, an E3 ubiquitin ligase. In hippocampal cultures, CPEB3 activated by Neuralized1-mediated ubiquitination leads both to the growth of new dendritic spines and to an increase of the GluA1 and GluA2 subunits of AMPA receptors, two CPEB3 targets essential for synaptic plasticity. Conditional overexpression of Neuralized1 similarly increases GluA1 and GluA2 and the number of spines and functional synapses in the hippocampus and is reflected in enhanced hippocampal-dependent memory and synaptic plasticity. By contrast, inhibition of Neuralized1 reduces GluA1 and GluA2 levels and impairs hippocampal-dependent memory and synaptic plasticity. These results suggest a model whereby Neuralized1-dependent ubiquitination facilitates hippocampal plasticity and hippocampal-dependent memory storage by modulating the activity of CPEB3 and CPEB3-dependent protein synthesis and synapse formation.

A dual role for the adaptor protein DRK in Drosophila olfactory learning and memory.

Participation of RAS, RAF, and mitogen-activated protein kinase (MAPK) in learning and memory has been demonstrated in a number of studies, but the molecular events requisite for cascade activation and regulation have not been explored. We demonstrate that the adapter protein DRK (downstream of receptor kinase) which is essential for signaling to RAS in developmental contexts, is preferentially distributed in the adult mushroom bodies, centers for olfactory learning and memory. We demonstrate that drk mutant heterozygotes exhibit deficits in olfactory learning and memory, apparent under limited training conditions, but are not impaired in sensory responses requisite for the association of the stimuli, or brain neuroanatomy. Furthermore, we demonstrate that the protein is required acutely within mushroom body neurons to mediate efficient learning, a process that requires RAF activation. Importantly, 90 min memory remained impaired, even after differential training yielding equivalent learning in animals with compromised DRK levels and controls and did not require RAF. Sustained MAPK activation is compromised in drk mutants and surprisingly is negatively regulated by constitutive RAF activity. The data establish a role for DRK in Drosophila behavioral neuroplasticity and suggest a dual role for the protein, first in RAF activation-dependent learning and additionally in RAF-inhibition dependent sustained MAPK activation essential for memory formation or stability.

Neuralized is expressed in the alpha/beta lobes of adult Drosophila mushroom bodies and facilitates olfactory long-term memory formation.

Memory formation involves multiple molecular mechanisms, the nature and components of which are essential to understand these processes. Drosophila is a powerful model to identify genes important for the formation and storage of consolidated memories because the molecular mechanisms and dependence of these processes on particular brain regions appear to be generally conserved. We present evidence that the highly conserved ubiquitin ligase Neuralized (Neur) is expressed in the adult Drosophila mushroom body (MB) alpha/beta lobe peripheral neurons and is a limiting factor for the formation of long-term memory (LTM). We show that loss of one copy of neur gene results in significant LTM impairment, whereas overexpression of Neur in the peripheral neurons of the alpha/beta lobes of the adult MBs results in a dosage-dependent enhancement of LTM. In contrast, learning, early memories, or anesthesia-resistant memory are not affected. We also demonstrate that the role of Neuralized in LTM formation is restricted within the neurons of the periphery of the alpha/beta lobes, and we suggest that this structural subdivision of the MBs participates in the formation of LTM.

Learning and memory deficits upon TAU accumulation in Drosophila mushroom body neurons.

Mutations in the neuronal-specific microtubule-binding protein TAU are associated with several dementias and neurodegenerative diseases. However, the effects of elevated TAU accumulation on behavioral plasticity are unknown. We report that directed expression of wild-type vertebrate and Drosophila TAU in adult mushroom body neurons, centers for olfactory learning and memory in Drosophila, strongly compromised associative olfactory learning and memory, but olfactory conditioning-relevant osmotactic and mechanosensory responses remained intact. In addition, TAU accumulation in mushroom body neurons did not result in detectable neurodegeneration or premature death. Therefore, TAU-mediated structural or functional perturbation of the microtubular cytoskeleton in mushroom body neurons is likely causal of the behavioral deficit. These results indicate that behavioral plasticity decrements may be the earliest detectable manifestations of tauopathies.

Cloning, chromosomal organization and expression analysis of Neurl, the mouse homolog of Drosophila melanogaster neuralized gene.

The Drosophila neuralized (neur) gene belongs to the neurogenic group of genes involved in regulating cell-cell interactions required for neural precursor development. neur mutant phenotypes include strong overcommitment to neural fates at the expense of epidermal fates. The human neuralized homolog (NEURL) has been recently determined and found to map to chromosome 10q25.1 within the region frequently deleted in malignant astrocytomas. Because of its potential importance in developmental processes, we analyzed the structure of the mouse homolog, Neurl, and its expression pattern in embryonic tissues. Neurl activity is detected from early developmental stages in several tissues and organs including neural tissues, limbs, the skeletal system, sense organs and internal organs undergoing epithelial-mesenchymal interactions. Neurl encodes a polypeptide associated with the plasma membrane but also detected in the cytoplasm. Similarly to the Drosophila gene, mammalian neuralized may code for an important regulatory factor.