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Brewer, J.

Publications and source records attributed to Brewer, J..

At least 19 recordsLinked to original sources

A phage-encoded host transcription modulator, Htm, reprograms the transcriptome of ESBL Escherichia coli

During phage infection, phages reprogram their host to secure energy, building blocks for their genome, and proteins, as well as the transcription and translation machinery required to replicate their genome and produce phage particles. This also includes reprogramming the host transcriptome to modify host gene expression and align it with the needs of the phage during infection. In this study, we present a putative early-expressed protein, Gp204 of Mosigvirus AV110, renamed Host transcription modulator (Htm), that has a broad impact on the extended-spectrum beta-lactamase (ESBL)- associated E. coli transcriptome. Overexpression of Htm decreased the growth rate of ESBL-E. coli and caused DNA condensation. Htm is structurally similar to bacterial enhancer-binding proteins, binds ssDNA, and alters the expression levels of over 700 E. coli genes when expressed. The majority of these genes were upregulated and are involved in multiple pathways, such as galactose metabolism and pentose and glucuronate interconversions, which may promote the synthesis of purines, pyrimidines, and histidine, all of which are required for the replication, transcription, and translation of the phage genome. Furthermore, energy production is likely to be upregulated by increased availability of acetyl-CoA, resulting from, among other factors, fatty acid degradation. Htm also downregulated the expression of the structural genes involved in flagellar assembly and multiple two-component systems. In conclusion, Htm could promote phage progeny production by increasing the availability of nucleotides, amino acids, and energy, while inhibiting non-essential processes, such as flagella formation.

microbiology↗

Patient-Derived Air-Liquid Interface Forebrain Organoids Reveal Functional Synaptic Deficits in Schizophrenia

Schizophrenia (SCZ) is a severe and debilitating neurodevelopmental disorder with lifelong impact on everyday life. Disruptions in synapse functions play a key role in its complex and poorly understood etiological and pathological mechanisms. Here, we investigated both the molecular composition and the spontaneous and stimulated functional properties of synapses in neural organoids from SCZ individuals. Air-liquid interface forebrain organoids (ALI-FOs) were generated from induced pluripotent stem cells (iPSCs) derived from three individuals with SCZ and three healthy controls. At day 170 synaptosomes were enriched and analyzed by data-independent acquisition mass spectrometry to profile the proteome, alongside with TMT-labeled phosphoproteomics both before and after acute KCl-induced depolarization. In parallel, we characterized the PTMome of the surrounding cellular environment, comprising phosphorylation, peptides with free and reversibly modified cysteines, and sialylated N-linked glycopeptides. Functional glutamatergic and GABAergic activity was assessed using calcium imaging to capture spontaneous neuronal signaling. Both conditions exhibited mature synaptic structures, while growth cones were observed only in SCZ-derived ALI-FOs, indicative of ongoing or delayed synaptogenesis. Proteomic analysis of synaptosome preparations revealed 358 differentially regulated proteins between SCZ and controls and 125 phophoproteins with altered phosphorylation, which clustered into three major categories: (1) synaptogenesis and synapse signaling; (2) cytoskeleton and cell junctions; (3) growth cone dynamics and neurite outgrowth. Analysis of the PTMs in the surrounding cellular environment revealed regulation of key regulatory mechanisms in 526 proteins, supporting the synaptic alterations observed. Notably, components of the Wnt signaling pathway were consistently dysregulated across both the synaptosome preparation and the PTMome in SCZ-derived ALIFOs as compared to controls. Depolarization-induced phospho-signaling revealed SCZ-specific response enriched in synaptic vesicle trafficking pathways. Together, these findings provide new insights into early synaptic alterations in SCZ, highlighting changes not only in protein composition, but more in protein regulatory mechanisms underlying synaptic signaling.

neuroscience↗

Protein-state dysregulation and sex-specific neurodevelopmental signatures in schizophrenia forebrain organoids

Schizophrenia is highly heritable, yet the molecular mechanisms linking genetic risk to abnormal human brain development remain poorly understood. To address this, we generated dorsal forebrain organoids from 17 individuals with idiopathic schizophrenia and 17 age- and sex-matched controls and profiled them across multiple molecular layers, including single-nucleus transcriptomics, quantitative proteomics, metabolomics and deep post-translational modification (PTM) analysis. The organoids reproducibly modelled early cortical development and showed largely similar cellular composition between schizophrenia and control groups. Surprisingly, transcriptomic differences were relatively limited, with the strongest cell-type-specific changes observed in Cajal-Retzius neurons. In contrast, proteomic and particularly PTM-level analyses revealed widespread molecular disruption affecting pathways involved in neuronal migration, neurite development, synaptic function, protein kinase signalling, extracellular matrix organisation and lipid metabolism. Many of the earliest disease-associated changes emerged at the level of protein phosphorylation, consistent with altered neuronal maturation and neurite dynamics. At later developmental stages, schizophrenia organoids showed reduced abundance of synaptic proteins, fewer synaptic puncta and evidence of dysregulated retinoic acid and YAP1 signalling. Notably, most disease-associated alterations occurred independently of changes in transcript or protein abundance, indicating that key aspects of schizophrenia biology are encoded in protein state rather than expression level. These findings identify sex-specific dysregulation of protein state as a major molecular feature of schizophrenia and demonstrate the value of multi-layer proteomic approaches for uncovering disease mechanisms missed by transcriptomics alone.

neuroscience↗

A network for self-transcendence derived from patients with brain lesions

Self-transcendence, the reorientation of experience away from the self toward others, nature, or broader meaning, is a fundamental dimension of human psychology, yet its causal neural architecture remains poorly understood. Here we applied lesion network mapping to 88 neurosurgical patients with pre- and post-operative assessments of trait self-transcendence to identify the distributed brain network whose disruption alters this capacity. The resulting network showed significant spatial correspondence with the default mode network and, at a finer parcellation level, with frontoparietal control subnetworks. Leave-one-out analyses identified posterior midline regions as the most stable correlates of increased self-transcendence following brain lesions. Independent validation against fMRI meta-analyses of self-referential processing, compassion, and ketamine administration, alongside a neuromodulation target previously shown to modulate the sense of self, converged on a consistent model. These findings provide causal evidence for a network architecture in which posterior midline hubs constrain, and brainstem and anterior midline regions facilitate, self-transcendent experience.

neuroscience↗

Structural basis for loading of Transcription Repair-Coupling factor Mfd onto stalled elongation complexes

Transcription-coupled repair (TCR) is a nucleotide excision repair sub-pathway that preferentially removes lesions from the DNA template-strand stalling RNA polymerase (RNAP) elongation complexes (ECs). In bacteria, the superfamily 2 Mfd translocase mediates TCR by displacing stalled ECs and recruiting Uvr(A)B. Using cryo-electron microscopy, we previously visualized seven Mfd-EC complexes spanning the ATP-dependent Mfd loading and EC displacement pathway [L1 -> L2(ADP) -> C1(ATP) -> C2(ATP) -> C3(ADP) -> C4(ADP) -> C5(ATP)]. The first intermediate (L1) was poorly resolved (4.1 [A] nominal resolution) due to low particle occupancy. The pathway is characterized by very large Mfd structural transitions, notably the L1 -> L2 transition. Here, we pre-loaded Mfd with ATP in the presence of the{gamma} -phosphate mimic, BeF3-, limiting rounds of ATP hydrolysis. The resulting accumulation of early intermediates allowed us to resolve the L1 intermediate to 3.5 [A] nominal resolution, revealing bound ADP-BeF3-. We also identified a new intermediate between L1 and L2, L1.5, providing further insight into Mfd conformational changes during loading. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/674597v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@1472098org.highwire.dtl.DTLVardef@acfca3org.highwire.dtl.DTLVardef@fe4424org.highwire.dtl.DTLVardef@12bc521_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

PAF15-PCNA assembly exhaustion governs lagging strand replication and replisome integrity

Genome replication in eukaryotic cells is surveyed by the S-phase checkpoint, which orchestrates sequential replication origin activation to avoid exhaustion of hitherto poorly defined rate-limiting replisome components. Here, we find that excessive activation of replication origins depletes chromatin-bound PCNA and lagging strand components, thereby limiting additional PCNA loading at new origins when checkpoint control is disrupted. PAF15 (PCNA-associated factor 15) emerges as a dosage-sensitive regulator of PCNA, delineating the dynamic range of global genome duplication and defining distinct roles for PCNA on the leading and lagging strands. Through its high-affinity PIP motif and interaction within the DNA encircling channel of PCNA, PAF15 stabilizes PCNA exclusively on the lagging strand, optimizing and rate-limiting lagging strand processing. On the other hand, misregulation of PAF15--whether by overexpression or mislocalization to the leading strand--impairs replication fork progression and leads to cell death. These defects are mitigated by TIMELESS and CLASPIN, which restrain PAF15-PCNA interactions beyond the lagging strand. E2F4-mediated repression orchestrates PAF15 expression in normal and cancer cells, maintaining its optimal dosage for lagging strand-specific interactions with PCNA. Thus, the S-phase checkpoint functions in concert to restrict origin activation when lagging strand PAF15-PCNA assembly is exhausted, linking a previously concealed strand-specific rate limitation to overall replication dynamics.

biochemistry↗

Isolation and characterization of synaptic structures from human neural organoids

Human neural organoids (NOs) provide a powerful platform for investigating synaptic development and dysfunction during early neurodevelopment. However, methodologies for isolating functional synaptic structures from these models remain limited. Here, we present a differential centrifugation protocol enabling the enrichment of growth cone particles (GCPs) and immature synaptosomes from air-liquid interface cerebral organoids (ALI-COs) at distinct developmental stages (day 90 and 150). Notably, the method avoids density gradients, requires minimal starting material while maintaining reproducibility across human and murine tissues. Quantitative proteomic profiling revealed significant enrichment of growth cone markers (e.g. GAP43) and classical synaptosomal proteins (e.g. PCLO, BSN, SYN1). Transmission electron microscopy (TEM) confirmed the presence of membrane-enclosed GCPs with fibrous content and mitochondria in day 90 isolates, and immature synaptosomes containing synaptic vesicles on day 150. Functional viability of both types of synaptic structures was demonstrated through KCl-induced depolarization, which triggered phosphorylation changes in growth cone proteins (GAP43, MARCKS, MARCKSL1), cytoskeletal regulators (DCLK1, SHTN1, MARK4, MAP1B) and protein kinases (CAMK2G, PRKCE) in day 90 GCPs, as well as classical synaptic vesicle cycle proteins (SYN1, DNM1, RPH3A) at day 150. Overall, this study establishes a centrifugation-based protocol for isolating growth cones and immature synapses from human organoids, capturing key stages of synaptic development and enabling scalable, patient-compatible models to study synaptic function and dysfunction in neurodevelopmental and neurodegenerative disorders.

neuroscience↗

Volumetric imaging and computation to explore contractile function in zebrafish hearts

Despite advancements in cardiovascular engineering, heart diseases remain a leading cause of mortality. The limited understanding of the underlying mechanisms of cardiac dysfunction at the cellular level restricts the development of effective screening and therapeutic methods. To address this, we have developed a framework that incorporates light field detection and individual cell tracking to capture real-time volumetric data in zebrafish hearts, which share structural and electrical similarities with the human heart and generate 120 to 180 beats per minute. Our results indicate that the in-house system achieves an acquisition speed of 200 volumes per second, with resolutions of up to 5.02 {+/-} 0.54 {micro}m laterally and 9.02 {+/-} 1.11 {micro}m axially across the entire depth, using the estimated-maximized-smoothed deconvolution method. The subsequent deep learning-based cell trackers enable further investigation of contractile dynamics, including cellular displacement and velocity, followed by volumetric tracking of specific cells of interest from end-systole to end-diastole in an interactive environment. Collectively, our strategy facilitates real-time volumetric imaging and assessment of contractile dynamics across the entire ventricle at the cellular resolution over multiple cycles, providing significant potential for exploring intercellular interactions in both health and disease.

bioengineering↗

Temporal proteomic and PTMomic atlas of cerebral organoid development

Cerebral organoids (CBOs) are generated from pluripotent stem cells that undergo neuroectoderm specification and neuronal differentiation in three dimensions. The developing neurons in CBOs migrate and self-organize into cerebral cortex-like layers, mimicking human brain development. CBOs develop according to intrinsic signaling mechanisms and offer unique insights into mechanisms of early human brain development. This process requires coordinated spatiotemporal regulation of protein expression and function, where the latter can be achieved by post-translational modifications (PTMs) on proteins. Despite the importance of proteins in brain development and function, profiling of protein abundance and the involvement of PTMs in CBO development remain underexplored. To gain insight into protein and PTM abundance in CBOs, we performed a high-resolution temporal analysis of CBOs up to day 200 using proteomics, PTMomics and metabolomics. We quantified more than 9,300 proteins and various neurodevelopmentally relevant PTMs (including phosphorylation, lysine acetylation, sialylated N-glycosylation, and cysteine modifications). We demonstrate that protein abundance and dynamic PTMs show significant temporal changes during CBO development related to neuronal differentiation and energy metabolism, whereas calcium signaling is mainly regulated by dynamic PTMs. We further show that synaptic protein content correlated with neurotransmitter levels, and we detected astroglia beyond day 100. Lastly, comparative analysis showed proteomic similarities between CBOs and human fetal brain tissue, supporting the physiological relevance of CBOs. Overall, our study presents a temporal atlas of protein and PTM abundance in CBOs and provides a valuable resource for studying neurodevelopment in neural organoids.

neuroscience↗

Scalable intracellular delivery via microfluidic vortex shedding enhances the function of chimeric antigen receptor T-cells

Adoptive chimeric antigen receptor T-cell (CAR-T) therapy is transformative and approved for hematologic malignancies. It is also being developed for the treatment of solid tumors, autoimmune disorders, heart disease, and aging. Despite unprecedented clinical outcomes, CAR-T and other engineered cell therapies face a variety of manufacturing and safety challenges. Traditional methods, such as lentivirus transduction and electroporation, result in random integration or cause significant cellular damage, which can limit the safety and efficacy of engineered cell therapies. We present hydroporation as a gentle and effective alternative for intracellular delivery. Hydroporation resulted in 1.7- to 2-fold higher CAR-T yields compared to electroporation with superior cell viability and recovery. Hydroporated cells exhibited rapid proliferation, robust target cell lysis, and increased pro-inflammatory and regulatory cytokine secretion in addition to improved CAR-T yield by day 5 post-transfection. We demonstrate that scaled-up hydroporation can process 5 x 108 cells in less than 10 s, showcasing the platform as a viable solution for high-yield CAR-T manufacturing with the potential for improved therapeutic outcomes.

bioengineering↗

Multi-omic analysis of guided and unguided forebrain organoids reveal differences in cellular composition and metabolic profiles

Neural organoids are invaluable model systems for studying neurodevelopment and neurological diseases. For this purpose, reproducible differentiation protocols are needed that minimize inter-organoid variability whilst generating neural organoids that physiologically resemble the brain area of interest. Currently, two main approaches are used: guided, where the differentiation towards neuroectoderm and subsequently specific CNS regions is driven by applying extrinsic signalling molecules, and unguided, where the intrinsic capability of pluripotent stem cells to generate neuroectoderm without external signalling is promoted. Despite the importance for the field, the resulting differences between these models have not been directly investigated. To obtain an unbiased comparison, we performed a multi-omic analysis of forebrain organoids generated using a guided and unguided approach focusing on proteomic, lipidomic and metabolomic differences. Furthermore, we characterised differences in phosphorylation and sialylation states of proteins, two key post-translational modifications (PTMs) in neurodevelopment, and performed single cell transcriptomics (scRNAseq). The multi-omic analysis revealed considerable differences in neuronal-, synaptic and glial content, indicating that guided forebrain organoids contain a larger proportion of neurons, including GABAergic interneurons, and synapses whereas unguided organoids contain significantly more GFAP+ cells and choroid plexus. Furthermore, substantial differences in mitochondrial- and metabolic profiles were identified, pointing to increased levels of oxidative phosphorylation and fatty acid {beta}-oxidation in unguided forebrain organoids and a higher reliance on glycolysis in guided forebrain organoids. Overall, our study comprises a thorough description of the multi-omic differences arising when generating guided and unguided forebrain organoids and provide an important resource for the organoid field studying neurodevelopment and -disease.

neuroscience↗

FLiPPR: A Processor for Limited Proteolysis (LiP) Mass Spectrometry Datasets Built on FragPipe

Here, we present FLiPPR, or FragPipe LiP (limited proteolysis) Processor, a tool that facilitates the analysis of data from limited proteolysis mass spectrometry (LiP-MS) experiments following primary search and quantification in FragPipe. LiP-MS has emerged as a method that can provide proteome-wide information on protein structure and has been applied to a range of biological and biophysical questions. Although LiP- MS can be carried out with standard laboratory reagents and mass spectrometers, analyzing the data can be slow and poses unique challenges compared to typical quantitative proteomics workflows. To address this, we leverage the fast, sensitive, and accurate search and label-free quantification algorithms in FragPipe and then process its output in FLiPPR. FLiPPR formalizes a specific data imputation heuristic that carefully uses missing data in LiP-MS experiments to report on the most significant structural changes. Moreover, FLiPPR introduces a new data merging scheme (from ions to cut-sites) and a protein-centric multiple hypothesis correction scheme, collectively enabling processed LiP-MS datasets to be more robust and less redundant. These improvements substantially strengthen statistical trends when previously published data are reanalyzed with the FragPipe/FLiPPR workflow. As a final feature, FLiPPR facilitates the collection of structural metadata to identify correlations between experiments and structural features. We hope that FLiPPR will lower the barrier for more users to adopt LiP-MS, standardize statistical procedures for LiP-MS data analysis, and systematize output to facilitate eventual larger-scale integration of LiP-MS data.

bioinformatics↗

Efficient Viral Capture and Inactivation from Bioaerosols Using Electrostatic Precipitation.

The presence of infectious viral particles in bioaerosols generated during laparoscopic surgery places surgical staff at significant risk of infection and represents a major cause of nosocomial infection. These factors contributed to the postponement and cancellation of countless surgical procedures during the early stages of the ongoing COVID-19 pandemic, causing backlogs, increased waiting times for surgical procedures and excess deaths indirectly related to the pandemic. The development and implementation of devices that effectively inactivate viral particles from bioaerosols would be beneficial in limiting or preventing the spread of infections from such bioaerosols. Here, we sought to evaluate whether electrostatic precipitation (EP) is a viable means to capture and inactivate both non-enveloped (Adenovirus) and enveloped (SARS-CoV-2 Pseudotyped Lentivirus) viral particles present in bioaerosols. We developed a closed-system model to mimic the release of bioaerosols during laparoscopic surgery. Known concentrations of each virus were aerosolised into the model system, exposed to EP using a commercially available system (UltravisionTM, Alesi Surgical Limited, UK) and collected in a BioSampler for analysis. Using qPCR to quantify viral genomes and transduction assays to quantify biological activity, we show that both enveloped and non-enveloped viral particles were efficiently captured and inactivated by EP. Both capture and inactivation could be further enhanced when increasing the voltage to 10kV, or when using two Ultravision discharge electrodes together at 8kV. This study highlights EP as an efficient means for capturing and inactivating viral particles present in bioaerosols. The use of EP may limit the spread of diseases, reducing nosocomial infections and potentially enable the continuation of surgical procedures during periods of viral pandemics. HighlightsO_LIBioaerosols released from patients during surgery have the potential to facilitate viral spread. C_LIO_LIUltravision technology works via the process of electrostatic precipitation. C_LIO_LIElectrostatic precipitation can be manipulated to capture and inactivate aerosolised viral particles, preventing viral spread. C_LIO_LIElectrostatic precipitation is effective against both enveloped and non-enveloped viral particles. C_LIO_LIElectrostatic precipitation represents a viable means to reduce nosocomial infections. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=99 SRC="FIGDIR/small/529105v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@4b7fb1org.highwire.dtl.DTLVardef@ac6edaorg.highwire.dtl.DTLVardef@a1ea28org.highwire.dtl.DTLVardef@13f6c7_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

Polarized α-synuclein trafficking and transcytosis across Brain Endothelial Cells via Rab7-decorated carriers

Parkinsons disease is mainly caused by aggregation of -synuclein (-syn) in the brain. Exchange of -syn between the brain and peripheral tissues could have important pathophysiological and therapeutic implications, but the trafficking mechanism of -syn across the blood brain barrier (BBB) remains unclear. In this study, we therefore investigated uptake and transport mechanisms of -syn monomers and oligomers across an in vitro BBB model system. Both -syn monomers and oligomers were internalized by primary brain endothelial cells, with increased restriction of oligomeric over monomeric transport. To enlighten the trafficking route of monomeric -syn in brain endothelial cells, we investigated co-localization of -syn and intracellular markers of vesicular transport. Here, we observed the highest colocalization with clathrin, Rab7 and VPS35, suggesting a clathrin-dependent internalization, preferentially followed by a late endosome retromer-connected trafficking pathway. Furthermore, STED microscopy revealed monomeric -syn trafficking via Rab7-decorated carriers. Knockdown of Caveolin1, VPS35, and Rab7 using siRNA did not affect monomeric -syn uptake into endothelial cells. However, it significantly reduced transcytosis of monomeric -syn in the luminal-abluminal direction, suggesting a polarized regulation of monomeric -syn vesicular transport. Our findings suggest a direct role for Rab7 in polarized trafficking of monomeric -syn across BBB endothelium, and the potential of Rab7 directed trafficking to constitute a target pathway for new therapeutic strategies against Parkinsons disease and related synucleinopathies. Significance StatementIn the submitted manuscript, we describe the use of a state-of-the-art porcine blood-brain barrier model based on primary cells to get information about this important issue. We identify several hitherto undescribed cellular pathways to mediate polarized transport of alpha-synuclein. One of these paths we find regulated by Rab7 and can be inhibited by targeting several intracellular proteins such as VPS35, Caveolin1 and Rab7. New knowledge describing brain endothelial intracellular transport systems are highly warranted for identifying new target to alleviate Parkinsons disease. We believe that our findings could be the seed to establish new therapeutic strategies against Parkinsons disease and related synucleinopathies.

cell biology↗

Singing-related reorganization of the song motor circuit is accompanied by a shift in hormonal modulation of song

Sex hormones are essential modulators of birdsong. Testosterone, and its active androgenic and estrogenic metabolites, 5-dihydrotestosterone (DHT) and estradiol, can re-shape the brain circuits responsible for song learning and production. The differential mechanisms of action of these different hormones during song development and song maintenance are, nonetheless, not fully understood. Here we demonstrate that unlike testosterone, DHT treatment does not induce singing behavior in naive adult female canaries that have never previously produced song. However, in birds with previous testosterone-induced singing experience, DHT alone is enough to promote the re-acquisition of high quality songs, even after months of silence. In addition, we show that the synaptic reorganization that accompanies vocal motor skill development requires more than DHT-induced androgen receptor activation. These results indicate that vocal motor practice will persistently modify the hormone-sensitive brain circuit responsible for song production, suggesting a mechanistic differentiation in the hormone-dependent regulation of the initial vocal motor skill acquisition and later re-acquisition.

neuroscience↗

Structural basis for transcription complex disruption by the Mfd translocase

Transcription-coupled repair (TCR) is a sub-pathway of nucleotide excision repair (NER) that preferentially removes lesions from the template-strand (t-strand) that stall RNA polymerase (RNAP) elongation complexes (EC). Mfd mediates TCR in bacteria by removing the stalled RNAP concealing the lesion and recruiting Uvr(A)BC. We used cryo-electron microscopy to visualize Mfd engaging with a stalled EC and attempting to dislodge the RNAP. We visualized seven distinct Mfd-EC complexes in both ATP and ADP-bound states. The structures explain how Mfd is remodeled from its repressed conformation, how the UvrA-interacting surface of Mfd is hidden during most of the remodeling process to prevent premature engagement with the NER pathway, how Mfd alters the RNAP conformation to facilitate disassembly, and how Mfd forms a processive translocation complex after dislodging the RNAP. Our results reveal an elaborate mechanism for how Mfd kinetically discriminates paused from stalled ECs and disassembles stalled ECs to initiate TCR.

biophysics↗

Vocal motor experiences consolidate the vocal motor circuitry and accelerate future vocal skill development

Complex motor skills take considerable time and practice to learn. Without continued practice the level of skill performance quickly degrades, posing a problem for the timely utilization of skilled motor responses. Here we quantified the recurring development of vocal motor skills and the accompanying changes in synaptic connectivity in the brain of a songbird, while manipulating skill performance by consecutively administrating and withdrawing testosterone. We demonstrate that a songbird with prior singing experience can significantly accelerate the re-acquisition of vocal performance. We further demonstrate that an increase in vocal performance is accompanied by a pronounced synaptic pruning in the forebrain vocal motor area HVC, a reduction that is not reversed when birds stop singing. These results provide evidence that lasting synaptic changes in the motor circuitry are associated with the savings of motor skills, enabling a rapid recovery of motor performance under environmental time constraints.

animal behavior and cognition↗

Lipid associated polygenic enrichment in Alzheimer’s disease

Cardiovascular (CV) and lifestyle associated risk factors (RFs) are increasingly recognized as important for Alzheimers disease (AD) pathogenesis. Beyond the [isin]4 allele of apolipoprotein E (APOE), comparatively little is known about whether CV associated genes also increase risk for AD (genetic pleiotropy). Using large genome-wide association studies (GWASs) (total n > 500,000 cases and controls) and validated tools to quantify genetic pleiotropy, we systematically identified single nucleotide polymorphisms (SNPs) jointly associated with AD and one or more CV RFs, namely body mass index (BMI), type 2 diabetes (T2D), coronary artery disease (CAD), waist hip ratio (WHR), total cholesterol (TC), low-density (LDL) and high-density lipoprotein (HDL). In fold enrichment plots, we observed robust genetic enrichment in AD as a function of plasma lipids (TC, LDL, and HDL); we found minimal AD genetic enrichment conditional on BMI, T2D, CAD, and WHR. Beyond APOE, at conjunction FDR < 0.05 we identified 57 SNPs on 19 different chromosomes that were jointly associated with AD and CV outcomes including APOA4, ABCA1, ABCG5, LIPG, and MTCH2/SPI1. We found that common genetic variants influencing AD are associated with multiple CV RFs, at times with a different directionality of effect. Expression of these AD/CV pleiotropic genes was enriched for lipid metabolism processes, over-represented within astrocytes and vascular structures, highly co-expressed, and differentially altered within AD brains. Beyond APOE, we show that the polygenic component of AD is enriched for lipid associated RFs. Rather than a single causal link between genetic loci, RF and the outcome, we found that common genetic variants influencing AD are associated with multiple CV RFs. Our collective findings suggest that a network of genes involved in lipid biology also influence Alzheimers risk.

genetics↗