bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local synaptic inhibition mediates cerebellar granule cell pattern separation necessary for learned sensorimotor associations
Authors: Fleming Elizabeth A. , Field Greg D. , Tadross Michael R. , Hull Court 
Published: May 2022

AbstractThe cerebellar cortex plays a key role in generating predictive sensorimotor associations. To do so, the granule cell layer is thought to establish unique sensorimotor representations for learning. However, how this is achieved and how granule cell population responses contribute to behavior have remained unclear. To address these questions, we have used in vivo calcium imaging and granule cell-specific pharmacological manipulation of synaptic inhibition in awake, behaving mice. We find that inhibition sparsens and thresholds sensory responses, limiting overlap between sensory ensembles and preventing spiking in many granule cells that receive excitatory input. Moreover, we find that inhibition can be recruited in a stimulus-specific manner to powerfully decorrelate multisensory ensembles. Consistent with these results, we find that granule cell inhibition is required for sensory discrimination in a cerebellum-dependent behavior. These data thus reveal new mechanisms for granule cell layer pattern separation beyond those envisioned by classical models.
Actin filaments couple the protrusive tips to the nucleus through the I-BAR domain protein IRSp53 for migration of elongated cells on 1D fibers
Authors: Mukherjee Apratim , Ron Jonathan E. , Hu Hooi Ting , Nishimura Tamako , Hanawa-Suetsugu Kyoko , Behkam Bahareh , Gov Nir S. , Suetsugu Shiro , Nain Amrinder S. 
Published: May 2022

AbstractThe cell migration cycle proceeds with shaping the membrane to form new protrusive structures and redistribution of contractile machinery. The molecular mechanisms of cell migration are well-studied in 2D, but membrane shape-driven molecular migratory landscape in 3D fibrous matrices remains poorly described. 1D fibers recapitulate 3D migration, and here, we examined the role of membrane curvature regulator IRSp53 as a coupler between actin filaments and plasma membrane during cell migration on suspended 1D fibers. Cells attached, elongated, and migrated on the 1D fibers with the coiling of their leading-edge protrusions. IRSp53 depletion reduced cell-length spanning actin stress fibers, reduced protrusive activity, and contractility, leading to uncoupling of the nucleus from cellular movements. Using a theoretical model, the observed transition of IRSp53 depleted cells from rapid stick-slip migration to smooth, and slower migration was predicted to arise from reduced actin polymerization at the cell edges, which was verified by direct measurements of retrograde actin flow using speckle microscopy. Overall, we trace the effects of IRSp53 deep inside the cell from its actin-related activity at the cellular tips, thus demonstrating a unique role of IRSp53 in controlling cell migration in 3D.
Surveying non-visual arrestins reveals allosteric interactions between functional sites
Authors: Seckler James M. , Robinson Emily N. , Lewis Stephen J. , Grossfield Alan 
Published: May 2022

1.AbstractArrestins are important scaffolding proteins that are expressed in all vertebrate animals. They regulate cell signaling events upon binding to active G-protein coupled receptors (GPCR) and trigger endocytosis of active GPCRs. While many of the functional sites on arrestins have been characterized, the question of how these sites interact is unanswered. We used anisotropic network modelling (ANM) together with our covariance compliment techniques to survey all of the available structures of the non-visual arrestins to map how structural changes and protein-binding affect their structural dynamics. We found that activation and clathrin binding have a marked effect on arrestin dynamics, and that these dynamics changes are localized to a small number of distant functional sites. These sites include α-helix 1, the lariat loop, nuclear localization domain, and the C-domain β-sheets on the C-loop side. Our techniques suggest that clathrin binding and/or GPCR activation of arrestin perturb the dynamics of these sites independent of structural changes.
A GATA factor radiation in Caenorhabditis rewired the endoderm specification network
Authors: Darragh Antonia C. , Rifkin Scott A. 
Published: May 2022

AbstractAlthough similar developmental regulatory networks can produce diverse phenotypes, different networks can also produce the same phenotype. In theory, as long as development can produce an acceptable end phenotype, the details of the process could be shielded from selection, leading to the possibility of developmental system drift, where the developmental mechanisms underlying a stable phenotype continue to evolve. Many examples exist of divergent developmental genetics underlying conserved traits. However, studies that elucidate how these differences arose and how other features of development accommodated them are rarer. In Caenorhabditis elegans, six GATA-type transcription factors (GATA factors) comprise the zygotic part of the endoderm specification network. Here we show that the core of this network - five of the genes - originated within the genus during a brief but explosive radiation of this gene family and that at least three of them evolved from a single ancestral gene with at least two different spatio-temporal expression patterns. Based on analyses of their evolutionary history, gene structure, expression, and sequence, we explain how these GATA factors were integrated into this network. Our results show how gene duplication fueled the developmental system drift of the endoderm network in a phylogenetically brief period in developmentally canalized worms.
Acute Vaping of a golden Syrian Hamster is Feasible and Leads to Nicotine-Dependent Respiratory Tract Inflammation
Authors: Hinds Daniel M. , Nick Heidi J. , Vallin Tessa M. , Bloomquist Leslie A. , Christeson Sarah , Bratcher Preston E. , Cooper Emily H. , Brinton John T. , Bosco-Lauth Angela , White Carl W. 
Published: May 2022

ABSTRACTIntroductionE-cigarette vaping has become a major portion of nicotine consumption, especially for children and young adults. Although it is branded as a safer alternative to cigarette smoking, murine and rat models of sub-acute and chronic e-cigarette vaping exposure have shown many pro-inflammatory changes in the respiratory tract. An acute vaping exposure paradigm has not been demonstrated in the golden Syrian hamster, and the hamster is a readily available small animal model that has the unique benefit of becoming infected with and transmitting SARS-CoV-2 without genetic alteration to the animal or virus.MethodsUsing a two-day, whole-body vaping exposure protocol in male golden Syrian hamsters, we evaluated serum cotinine, bronchoalveolar lavage cells, lung and nasal histopathology, and gene expression in the nasopharynx and lung through RT-qPCR. Depending on the presence of nonnormality or outliers, statistical analysis was performed by ANOVA or Kruskal-Wallis tests. For tests that were statistically significant (p-value <0.05), post-hoc Tukey-Kramer and Dunn’s tests, respectively, were performed to make pairwise comparisons between groups.ResultsIn nasal tissue, RT-qPCR analysis revealed nicotine-dependent increases in genes associated with type 1 inflammation (CCL-5 and CXCL-10), fibrosis (TGF-β), and a nicotine-independent decrease in the vasculogenesis/angiogenesis gene VEGF-A. In the lung, nicotine-dependent increases in the expression of genes involved in the renin-angiotensin pathway (ACE, ACE2), coagulation (tissue factor, Serpine-1), extracellular matrix remodeling (MMP-2, MMP-9), type 1 inflammation (IL-1β, TNF-α, and CXCL-10), fibrosis (TGF-β and Serpine-1), oxidative stress response (SOD-2), neutrophil extracellular traps release (ELANE), and vasculogenesis and angiogenesis (VEGF-A) were identified.ConclusionTo our knowledge, this is the first demonstration that the Syrian hamster is a viable model of e-cig induced inhalational injury. In addition, this is the first report that e-cig vaping with nicotine can increase tissue factor gene expression in the lung. Our results show that even an acute exposure to e-cigarette vaping causes significant upregulation in the respiratory tract of pathways involving the renin-angiotensin system, coagulation, extracellular matrix remodeling, type 1 inflammation, fibrosis, oxidative stress response, NETosis, vasculogenesis, and angiogenesis.
Conformational Dynamics and Mechanisms of Client Protein Integration into the Hsp90 Chaperone Controlled by Allosteric Interactions of Regulatory Switches: Perturbation-Based Network Approach for Mutational Profiling of the Hsp90 Binding and Allostery
Authors: Verkhivker Gennady M. 
Published: May 2022

AbstractUnderstanding allosteric mechanisms of the Hsp90 chaperone interactions with cochaperones and client protein clientele is fundamental to dissect activation and regulation of many proteins. In this work, atomistic simulations are combined with perturbation-based approaches and dynamic network modeling for a comparative mutational profiling of the Hsp90 binding and allosteric interaction networks in the three Hsp90 maturation complexes with FKBP51 and P23 cochaperones and the glucocorticoid receptor (GR) client. The conformational dynamics signatures of the Hsp90 complexes and dynamics fluctuation analysis revealed how the intrinsic plasticity of the Hsp90 dimer can be modulated by cochaperone and client protein to stabilize the closed dimer state required at the maturation stage of the ATPase cycle. In silico deep mutational scanning of the protein residues characterized the hotspots of protein stability and binding affinity in the Hsp90 complexes, showing that binding hotspots may often coincide with the regulatory centers that modulate dynamic allostery in the Hsp90 dimer. We introduce a perturbation-based network approach for mutational scanning of allosteric residue potentials and characterize allosteric switch clusters that control mechanism of cochaperone-dependent client recognition and remodeling by the Hsp90 chaperone. The results revealed a conserved network of allosteric switches in the Hsp90 complexes that allow cochaperones and GR protein become integrated into the Hsp90 system by anchoring to the conformational switch points in the functional Hsp90 regions. This study suggests that the Hsp90 binding and allostery may operate under a regulatory mechanism in which activation or repression of the Hsp90 activity can be pre-encoded in the allosterically regulated Hsp90 dimer motions. By binding directly to the conformational switch centers on the Hsp90, cochaperones and interacting proteins can efficiently modulate allosteric interactions and long-range communications required for client remodeling and activation.
Repurposed drugs and their combinations prevent morbidity-inducing dermonecrosis caused by diverse cytotoxic snake venoms
Authors: Hall Steven R. , Rasmussen Sean A. , Crittenden Edouard , Dawson Charlotte A. , Bartlett Keirah E. , Westhorpe Adam P. , Albulescu Laura-Oana , Kool Jeroen , María Gutiérrez José , Casewell Nicholas R. 
Published: May 2022

AbstractMorbidity from snakebite envenoming affects approximately 400,000 people annually. Tissue damage at the bite-site often leaves victims with catastrophic life-long injuries and is largely untreatable by currently available antivenoms. Repurposing small molecule drugs that inhibit specific snake venom toxins offers a potential new treatment strategy for tackling this neglected tropical disease. Using human skin cell assays as an initial model for snakebite-induced dermonecrosis, we show that the repurposed drugs 2,3-dimercapto-1-propanesulfonic acid (DMPS), marimastat, and varespladib, alone or in combination, reduce the cytotoxic potency of a broad range of medically important snake venoms up to 5.7-fold. Thereafter, using a preclinical murine model of dermonecrosis, we demonstrate that the dual therapeutic combinations of DMPS or marimastat with varespladib potently inhibit the dermonecrotic activity of three geographically distinct and medically important snake venoms. These findings strongly support the future translation of repurposed drug combinations as broad-spectrum therapeutics for preventing morbidity caused by snakebite.
Characterization and structure of the human lysine-2-oxoglutarate reductase domain, a novel therapeutic target for treatment of glutaric aciduria type 1
Authors: Leandro João , Khamrui Susmita , Suebsuwong Chalada , Chen Peng-Jen , Secor Cody , Dodatko Tetyana , Yu Chunli , Sanchez Roberto , DeVita Robert J. , Houten Sander M. , Lazarus Michael B. 
Published: May 2022

ABSTRACTIn humans, a single enzyme 2-aminoadipic semialdehyde synthase (AASS) catalyzes the initial two critical reactions in the lysine degradation pathway. This enzyme evolved to be a bifunctional enzyme with both lysine 2-oxoglutarate reductase (LOR) and saccharopine dehydrogenase domains (SDH). Moreover, AASS is a unique drug target for metabolic genetic diseases such as glutaric aciduria type 1 that arise from deficiencies downstream in the lysine degradation pathway. While work has been done to elucidate the SDH domain structurally and to develop inhibitors, neither has been done for the LOR domain. Here, we purify and characterize LOR, show that AASS is rate-limiting upon high lysine exposure of mice, and present the crystal structure of the human LOR domain, which should enable future efforts to identify inhibitors of this novel drug target.
Probing the force-from-lipid mechanism with synthetic polymers
Authors: Jacobs Miranda L. , Steinkühler Jan , Lemley Audra , Larmore Megan J. , Gunnels Taylor F. , Ng Leo C. T. , Cologna Stephanie M. , DeCaen Paul G. , Kamat Neha P. 
Published: May 2022

AbstractA central feature of mechanotransduction is the ability of mechanosensitive channels to respond to mechanical stimuli from the surrounding lipid bilayer. Accordingly, the mechanical properties of membranes should play an important role in modulating force transmission to embedded channels, yet the nature of this relationship remains unclear for a wide class of mechanosensitive channels across prokaryotic and eukaryotic systems. Here, we use a synthetic amphiphile to modulate the membrane mechanical properties of cell-derived vesicles and probe channel activation. Using precise membrane mechanical characterization approaches that have rarely been used in conjunction with electrophysiology techniques, we directly characterize three membrane properties and the activation threshold of theE. colimechanosensitive channel of large conductance (MscL). Our study reveals that decreases in the membrane area expansion modulus, KA, and bending rigidity, kc, correlate with increases in the pressure required to activate MscL and that this effect is reproducible with the mammalian channel, TREK-1. MD simulations demonstrate that polymer-mediated changes in interfacial tension is the best mechanism to describe these experimental results. Together, our results bolster theforce-from-lipidsmechanism by demonstrating the generality of the relationship between changes in specific membrane mechanical properties and the gating pressure of MscL and TREK-1. In addition, our results reveal the mechanical mechanism by which membrane amphiphiles alter the activity and sensitivity of mechanosensitive channels through changes in long-range force transmission.
Emergent coexistence in multispecies microbial communities
Authors: Chang Chang-Yu , Bajic Djordje , Vila Jean , Estrela Sylvie , Sanchez Alvaro 
Published: May 2022

AbstractMicrobial communities are highly diverse, and understanding the factors that promote and modulate this diversity is a major area of research in microbial ecology. Recent work has proposed a reductionist perspective to microbial coexistence, where pairwise coexistence between strains in isolation is required for their coexistence in a more complex community. In this view, species exclusion in pairwise co-culture would preclude their coexistence in a more complex community too. An alternative view is that coexistence is a more complex property of the entire community, requiring the presence of additional community members. If this view were correct, competitive exclusion in pairwise co-culture would not necessarily preclude species coexistence in more complex community contexts. Empirically testing these alternative hypotheses is complicated by the intractably high microbial diversity of most natural communities, and the challenges of reconstituting every pair of coexisting species under the exact same habitat where their community of origin was assembled. To address this challenge, we have experimentally reconstituted all possible pairwise co-cultures between stably coexisting species from 13 different, low-diversity microbial enrichment communities, which had previously been assembled in a well-controlled synthetic habitat. We find that, when isolated from the rest of their community members, most species pairs fail to coexist. This result highlights the importance of community context for microbial coexistence and indicates that pairwise exclusion may not reflect the ability of species to coexist in more complex, multispecies ecosystems.
The Adaptor Protein 2 (AP2) complex modulates habituation and behavioral selection across multiple pathways and time windows
Authors: Mouret Rodrigo Zúñiga , Greenbaum Jordyn P. , Doll Hannah M. , Brody Eliza M. , Iacobucci Emma L. , Roland Nicholas C. , Simamora Roy C. , Ruiz Ivan , Seymour Rory , Ludwick Leanne , Groneberg Antonia H. , Marques João C. , Laborde Alexandre , Rajan Gokul , Bene Filippo Del , Orger Michael B. , Jain Roshan A. 
Published: May 2022

ABSTRACTAnimals constantly perceive and integrate information across sensory modalities, and their nervous systems must select behavioral responses appropriate to the current situation and prior experience. Genetic factors supporting this behavioral flexibility are often disrupted in neuropsychiatric conditions, and our previous work revealed the disease-associatedap2s1gene critically supports habituation learning in acoustically-evoked escape behavior of zebrafish.ap2s1encodes a subunit of the AP2 endocytosis adaptor complex and has been linked to autism spectrum disorder, though its mechanism and direct behavioral importance have not been established. Here, we show that multiple subunits of the AP2 complex regulate acoustically-evoked behavior selection and habituation learning. Furthermore,ap2s1biases the choice between distinct escape behaviors in sensory modality-specific manners, and more broadly regulates action selection across different sensory contexts. Using tissue-specific and inducible transgenic rescue, we demonstrate that the AP2 complex functions acutely and in the nervous system to modulate acoustically-evoked habituation learning, suggesting several spatially and/or temporally distinct mechanisms through which AP2 regulates different aspects of escape behavior selection and performance. Altogether, we demonstrate that the AP2 complex coordinates action selection across stimulus modalities and contexts, providing a new vertebrate model for the role ofap2s1in human conditions including autism spectrum disorder.SIGNIFICANCE STATEMENTTheAP2S1gene has been linked to learning disabilities and autism spectrum disorders (ASD), though the mechanisms underlying its impact on human behavior are unknown. We explored how, when, and where this gene regulates vertebrate behavior, developing a zebrafish model to identify the roles and mechanisms through whichap2s1modulates behavior. We find thatap2s1regulates simple acoustically-evoked learning, as well as how individuals bias behavioral choice in a wide variety of contexts. We show thatap2s1acts at multiple distinct time periods and locations both within and outside of neuronal tissues, revealing the diverse mechanisms and pathways through which it modulates vertebrate behavior.
AGS3 antagonizes LGN to balance oriented cell divisions and cell fate choices in mammalian epidermis
Authors: Descovich Carlos Patiño , Lough Kendall J. , Jena Akankshya , Wu Jessica J , Yom Jina , Spitzer Danielle C. , Uppalapati Manuela , Kedziora Katarzyna M. , Williams Scott E. 
Published: May 2022

ABSTRACTOriented cell divisions balance self-renewal and differentiation in stratified epithelia such as the skin epidermis. During peak epidermal stratification, the distribution of division angles among basal keratinocyte progenitors is bimodal, with planar and perpendicular divisions driving symmetric and asymmetric daughter cell fates, respectively. An apically-polarized, evolutionarily-conserved spindle orientation complex that includes the scaffolding protein LGN/Pins/Gpsm2 plays a central role in promoting perpendicular divisions and stratification, but little is known about the molecular regulation of planar divisions. Here, we demonstrate that the LGN paralog, AGS3/Gpsm1, is a novel negative regulator of LGN, and inhibits perpendicular divisions. Static and ex vivo live imaging reveal that AGS3 overexpression displaces LGN from the apical cortex and increases planar orientations, while AGS3 loss prolongs cortical LGN localization and leads to a perpendicular orientation bias. Genetic epistasis experiments in double mutants confirm that AGS3 operates through LGN. Finally, clonal lineage tracing shows that LGN and AGS3 promote asymmetric and symmetric fates, respectively, while also influencing differentiation through delamination. Collectively, these studies shed new light into how spindle orientation influences epidermal stratification.
Retigabine Suppresses Loss of Force in a Mouse Model of Hypokalemic Periodic Paralysis
Authors: Quiñonez Marbella , Cannon Stephen C. 
Published: May 2022

ABSTRACTObjectiveThe goal of this experimental study was to test the hypothesis that the potassium channel opener retigabine can prevent the episodic loss of force in hypokalemic periodic paralysis (HypoPP).MethodsA knock-in mutant mouse model of HypoPP (Scn4a p.R669H) was used to determine whether pretreatment with retigabine suppressed the loss of force, or post-treatment hastened recovery of force for a low-K+ challenge in an ex vivo contraction assay.ResultsRetigabine completely prevents the loss of force induced by a 2 mM K+ challenge (protection) in our mouse model of HypoPP, with a 50% inhibitory concentration (IC50) of 0.8 µM. In comparison, the effective concentration for the KATP channel opener pinacidil was ten-fold higher. Application of retigabine also reversed the loss of force (rescue) for HypoPP muscle maintained in 2 mM K+.InterpretationRetigabine, a selective agonist of the KV7 family of potassium channels, is effective for the prevention of low-K+ induced attacks of weakness and to enhance recovery from an on-going loss of force in a mouse model of HypoPP. Substantial protection from the loss of force occurred in the low micromolar range, well within the therapeutic window for retigabine.