Biology subjects

Liang, B.

Publications and source records attributed to Liang, B..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

Distinct prelimbic cortex ensembles encode response execution and inhibition

Learning when to initiate or withhold actions is essential for survival and requires integration of past experiences with new information to adapt to changing environments. While stable prelimbic cortex (PL) ensembles have been identified during reward learning, it remains unclear how they adapt when contingencies shift. Does the same ensemble adjust its activity to support behavioral suppression upon reward omission, or is a distinct ensemble recruited for this new learning? We used single-cell calcium imaging to longitudinally track PL neurons in rats across operant food reward Training, Extinction and Reinstatement, trained rat-specific decoders to predict trial-wise behavior, and implemented an in-silico deletion approach to characterize ensemble contributions to behavior. We show that operant training and extinction recruit distinct PL ensembles that encode response execution and inhibition, and that both ensembles are re-engaged and maintain their roles during Reinstatement. These findings highlight ensemble-based encoding of multiple learned associations within a region, with selective ensemble recruitment supporting behavioral flexibility under changing contingencies.

neuroscience↗

bioRxiv2024

Vaccine-induced and hybrid immunity against SARS-CoV-2 variants of concern in two cohorts in Queensland, Australia (2021-2022).

The spike glycoprotein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the main target for vaccine development, as antibodies generated against the spike protein are the most immunodominant and neutralizing against the virus. However, variants of concern (VOC), often containing multiple mutations within neutralizing epitopes, confer immune evasion of the response generated by current SARS-CoV-2 vaccines. To assess the immunogenicity and virus-neutralisation ability of antibodies induced by individual or combination of Vaxzevria (AstraZeneca: AZ) and Comirnaty (Pfizer: PZ) vaccines and of a hybrid immunity induced in people who were also infected with SARS-CoV-2, longitudinal sera samples of participants recruited through the David Serisier Research biobank (Mater Research Hospital) or at the University of Queensland were collected. ELISA with a panel of purified Spike proteins from ancestral, alpha, delta and omicron BA.1 and BA.2 VOCs showed significantly (by [~]2 to 6-fold) reduced IgG antibody titres against Spike proteins from Omicron BA.1 and BA.2 compared to ancestral strain regardless of the number of vaccinations or presence of infection. Neutralisation assays showed reduced activity against delta and omicron BA.1, BA.5 and BA.5 VOCs. However, the differences were in general less pronounced than in the ELISA assay and some were not statistically significant, particularly after four (two AZ and two PZ) vaccinations. We also generated by circular polymerase extension reaction an attenuated SARS-CoV-2 strain with deletion of all accessory genes, ORF 3, 6, 7 and 8, based on the ancestral (QLD02) virus backbone (QLD02{Delta}3678) and validated it in virus-neutralization assays with our panel of sera samples. We showed the attenuation of the QLD02{Delta}3678 virus in Vero E6 and human Caco2 cells. We demonstrated that neutralization assays with the wild-type QLD02 virus and QLD02{Delta}3678 virus were concordant, providing a safe platform for neutralisation assays in BSL2/PC2 settings.

microbiology↗

bioRxiv2024

Intraperitoneal programming of tailored CAR macrophages via mRNA-LNP to boost cancer immunotherapy

Therapeutic strategies for peritoneal metastasis in solid tumors are urgently needed in the clinic. Programming chimeric antigen receptor macrophages (CAR-Ms) in situ offers opportunities for an unmet demand. However, potential intracellular domains (ICDs) for CAR design and their antitumor mechanisms for macrophage empowerment remain to be explored systematically. By developing a targeted mRNA-LNP delivery system for macrophages, we have investigated 36 CAR combinations to determine the impact of CAR-Ms on immune regulation in vitro and in vivo. In two solid tumor mouse models, intraperitoneal programming of CAR-Ms was shown to elicit robust adaptive immune activation and significantly synergize with PD-1/L1 therapy. Single-cell RNA sequencing (scRNA-seq) analysis revealed that CAR-Ms could reshape the immunosuppressive tumor microenvironment (TME) and boost the TCF1+PD-1+ progenitor- exhausted CD8+ T cells (Tpex) population. Meanwhile, we found that tailored CAR-M with CD3{zeta}/TLR4 ICDs could favorably maintain proinflammatory phenotype and simultaneously upregulate MHC I and PD-L1 expression by perturbing NF-{kappa}B pathways. Moreover, the synergism between macrophage PD-L1 knockdown and CAR-M therapy highlighted the need to block the PD-1/L1 axis in antigen cross-presentation. In short, we developed an mRNA-LNP delivery system for intraperitoneal programming of tailored CAR-Ms in vivo and broadened understanding of both regulatory and feedback mechanisms for CAR-M therapies against solid tumors.

bioengineering↗

bioRxiv2024

SASH1 impairs melanin synthesis and metastasis by down-regulating the TGF-β signaling pathway

Dyschromatosis universalis hereditaria (DUH) is a rare genetic dermatosis characterized by widespread hyperpigmentation and depigmentation. In our previous study, we identified SH3 domain-containing protein 1 (SASH1) mutations associated with the DUH phenotype in Chinese families and predict SASH1/THBS1/TGF-{beta}1 signaling to mediate melanin production and melanocyte transport. We detected SASH1/THBS1/TGF-{beta}1 pathway genes expression and evaluated cell phenotypes and melanin synthesis in A375 and PIG1 cell lines by regulating the expression of SASH1 and THBS1 respectively. Finally, we validated the results of the cellular experiments in nude mice. Results showed that SASH1 inhibited the proliferation, migration, invasion, EMT ability and melanin synthesis via TGF-{beta}1 signaling, and THBS1 reversed the elevation of TGF-{beta}1 caused by SASH1 knockdown. We demonstrated that SASH1 further inhibits TGF-{beta}1 through its regulatory effect on THBS1, thereby inhibiting melanin synthesis and metastasis, which may advance the utilization of TGF-{beta}1 for therapeutic purposes. Plain Language SummaryDyschromatosis universalis hereditaria(DUH) is a genetic disease showing uneven pigment pattern, which greatly affects the appearance. In our previous study, we had reported a SASH1 mutation in a Chinese DUH pedigree. In this study, we mainly focus on the effect of SASH1 gene on pigment synthesis and metabolism at the cell and animal level. The results show SASH1 inhibits the melanin synthesis of melanocytes, it can also hinder cell migration, invasion, and EMT. More than that, SASH1 reduced TGF-{beta}1 mRNA, protein expression and promoter activity, and THBS1 could discharge this effect. In mice, SASH1 inhibits the tumor growth via TGF-{beta}1 signaling. We detected a novel SASH1/THBS1/TGF-{beta}1 pathway in cell phenotypes and melanin synthesis.

cell biology↗

bioRxiv2024

Combinatorial Wnt Signaling induces Margin Color Elements in Swallowtail Butterfly Ground Plan.

The intricate wing patterns of butterflies are thought to derive from a morphological ground plan that anchors homology relationships between individual color pattern elements and serves as an archetype for comparative analysis. These patterns undergo modifications that drive the diverse morphologies observed in nature. While brush-footed butterflies (Nymphalidae) have been well studied, assigning homologies with other lepidopteran families remains challenging due to substantial divergence. Here, we focus on swallowtails (Papilionidae), an early-diverging butterfly lineage known for its outstanding diversity in wing shapes and patterns but lacking a developmental framework. Through qualitative and phylogenetic analyses, CRISPR perturbation assays, and in situ expression experiments, we investigate homologies between papilionid butterflies, offering phylogenetic and molecular characterization of the Papilionidae wing ground plan. Our results highlight the roles of WntA and Wnt6 in patterning papilionid signature wing elements, such as the glauca and the Submarginal spots. Notably, the nymphalids distinct Central Symmetry System is either reduced or absent in the family, with marginal systems expanding proximally. Our data illuminate a highly adaptable patterning system driven by Wnt signaling pathways in developing butterfly wings.

developmental biology↗

bioRxiv2024

Targeting Iron - Respiratory Reciprocity Promotes Bacterial Death

Discovering new bacterial signaling pathways offers unique antibiotic strategies. Here, through an unbiased resistance screen of 3,884 gene knockout strains, we uncovered a previously unknown non-lytic bactericidal mechanism that sequentially couples three transporters and downstream transcription to lethally suppress respiration of the highly virulent P. aeruginosa strain PA14 - one of three species on the WHOs Priority 1: Critical list. By targeting outer membrane YaiW, cationic lacritin peptide N-104 translocates into the periplasm where it ligates outer loops 4 and 2 of the inner membrane transporters FeoB and PotH, respectively, to suppress both ferrous iron and polyamine uptake. This broadly shuts down transcription of many biofilm-associated genes, including ferrous iron-dependent TauD and ExbB1. The mechanism is innate to the surface of the eye and is enhanced by synergistic coupling with thrombin peptide GKY20. This is the first example of an inhibitor of multiple bacterial transporters.

microbiology↗

bioRxiv2024

Psilocybin Promotes Cell-Type-Specific Changes in the Orbitofrontal Cortex Revealed by Single-Nucleus RNA-seq

Recent clinical breakthroughs hold great promise for the application of psilocybin in the treatments of psychological disorders, such as depression, addiction, and obsessive-compulsive disorder. Psilocybin is a psychedelic whose metabolite, psilocin, is a 5-HT2A receptor agonist. Nevertheless, the underlying mechanisms for the effects of psilocybin on the brain are not fully illustrated, and cell type-specific and circuit effects of psilocybin are not fully understood. Here, we combined single-nucleus RNA-seq with functional assays to study the long-term effects of psilocybin on the orbitofrontal cortex (OFC), a brain region vulnerable to psychological disorders such as depression. We showed that a single dose of psilocybin induced long-term genetic and functional changes in neurons of the OFC, and excitatory and inhibitory neurons collectively reduced circuit activity of the brain region. Knockdown of 5-HT2A receptor in deep layer excitatory neurons abated psilocybin-induced functional changes and the anti-depressant effect. Together, these results showed the cell type-specific mechanisms of psilocybin and shed light on the brain region difference in the effect of psychedelics.

neuroscience↗

bioRxiv2023

Sculpting conducting nanopore size and shape through de novo protein design

Transmembrane {beta}-barrels (TMBs) are widely used for single molecule DNA and RNA sequencing and have considerable potential for a broad range of sensing and sequencing applications. Current engineering approaches for nanopore sensors are limited to naturally occurring channels such as CsgG, which have evolved to carry out functions very different from sensing, and hence provide sub-optimal starting points. In contrast, de novo protein design can in principle create an unlimited number of new nanopores with any desired properties. Here we describe a general approach to the design of transmembrane {beta}-barrel pores with different diameter and pore geometry. NMR and crystallographic characterization shows that the designs are stably folded with structures close to the design models. We report the first examples of de novo designed TMBs with 10, 12 and 14 stranded {beta}-barrels. The designs have distinct conductances that correlate with their pore diameter, ranging from 110 pS ([~]0.5 nm pore diameter) to 430 pS ([~]1.1 nm pore diameter), and can be converted into sensitive small-molecule sensors with high signal to noise ratio. The capability to generate on demand {beta}-barrel pores of defined geometry opens up fundamentally new opportunities for custom engineering of sequencing and sensing technologies. One sentence summaryDe novo design enables the generation of stable and quite transmembrane beta-barrel nanopores with tailored sizes, shapes and properties.

synthetic biology↗

bioRxiv2023

Mapping ovarian cancer spatial organization uncovers immune evasion drivers at the genetic, cellular, and tissue level

Immune exclusion and evasion are central barriers to the success of immunotherapies and cell therapies in solid tumors. Here we applied single cell spatial and perturbational transcriptomics alongside clinical, histological, and genomic profiling to elucidate immune exclusion and evasion in high-grade serous tubo-ovarian cancer (HGSC). Using high-plex spatial transcriptomics we profiled more than 1.3 million cells from 95 tumors and 60 patients, revealing generalizable principles in HGSC tumor tissue organization. Our data demonstrates that effector T cells resist stroma-mediated trapping and sequestration. However, upon infiltration into the tumor, T cells, as well as Natural Killer (NK) cells, preferentially co-localize only with a subset of malignant cells that manifest a distinct transcriptional cell state. The latter consists of dozens of co-regulated genes and is repressed under various copy number alterations. Performing CRISPR Perturb-seq screens in ovarian cancer cells, we identified functionally diverse genetic perturbations - including knockout of the insulin sensing repressor PTPN1 and the epigenetic regulator ACTR8 - that de-repress the proposed immunogenic malignant cell state identified in patients and indeed sensitize ovarian cancer cells to T cell and NK cell cytotoxicity. Taken together, our study uncovered a profound connection between somatic genetic aberrations, malignant cell transcriptional dysregulation, and immune evasion at the cellular and tissue level, allowing us to identify targets that reprogram malignant cell states as an avenue to unleash anti-tumor immune responses.

cancer biology↗

bioRxiv2023

SIX4 Controls STING Expression Enhancing anti-PD-1 Efficacy

The cGAS/STING cytosolic DNA sensing pathway plays a central role in anti-tumor immunity. Expression of STING is tightly regulated and commonly reduced or defective in many types of cancer. We have identified SIX4 as a significant regulator of STING expression in colon cancer cells. We showed that knockout of SIX4 decreased STING expression at the mRNA and protein levels while ectopic expression of SIX4 increased STING expression. Depletion of SIX4 led to attenuated STING activation and downstream signaling. Re-expression of SIX4 or ectopic expression of STING in SIX4 knockout cells reversed the effect. Ectopic expression of SIX4 enhanced DMXAA and cGAMP-induced STING activation and downstream signaling. Importantly, decrease of SIX4 expression substantially decreased tumor infiltration of CD8+ T-cells and reduced the efficacy of PD-1 antibodies to diminish tumor growth in immune competent mice in vivo. Finally, analysis of TCGA colon cancer dataset indicated that tumors with high SIX4 expression were significantly enriched in the Inflammatory Response pathway. SIX4 expression also correlated with expression of multiple IFN-stimulated genes, inflammatory cytokines and CD8A. Taken together, our results implicate that SIX4 is a principal regulator of STING expression in colon cancer cells, providing an additional mechanism and genetic marker to predict effective immune checkpoint blockade therapy responses.

cancer biology↗

bioRxiv2023

The role of N-glycosylation in spike antigenicity for the SARS-CoV-2 Gamma variant

The emergence of SARS-CoV-2 variants alters the efficacy of existing immunity towards the viral spike protein, whether acquired from infection or vaccination. Mutations that impact N-glycosylation of spike may be particularly important in influencing antigenicity, but their consequences are difficult to predict. Here, we compare the glycosylation profiles and antigenicity of recombinant viral spike of ancestral Wu-1 and the Gamma strain, which has two additional N-glycosylation sites due to amino acid substitutions in the N-terminal domain (NTD). We found that a mutation at residue 20 from threonine to asparagine within the NTD caused the loss of NTD-specific antibody binding. Glycan site-occupancy analyses revealed that the mutation resulted in N-glycosylation switching to the new sequon at N20 from the native N17 site. Site-specific glycosylation profiles demonstrated distinct glycoform differences between Wu-1, Gamma, and selected NTD variant spike proteins, but these did not affect antibody binding. Finally, we evaluated the specificity of spike proteins against convalescent COVID-19 sera and found reduced cross-reactivity against some mutants, but not Gamma spike compared to Wuhan spike. Our results illustrate the impact of viral divergence on spike glycosylation and SARS-CoV-2 antibody binding profiles.

biochemistry↗

bioRxiv2023

Senolytic therapy alleviates physiological human brain aging and COVID-19 neuropathology.

Aging is the primary risk factor for most neurodegenerative diseases, and recently coronavirus disease 2019 (COVID-19) has been associated with severe neurological manifestations that can eventually impact neurodegenerative conditions in the long-term. The progressive accumulation of senescent cells in vivo strongly contributes to brain aging and neurodegenerative co-morbidities but the impact of virus-induced senescence in the aetiology of neuropathologies is unknown. Here, we show that senescent cells accumulate in physiologically aged brain organoids of human origin and that senolytic treatment reduces inflammation and cellular senescence; for which we found that combined treatment with the senolytic drugs dasatinib and quercetin rejuvenates transcriptomic human brain aging clocks. We further interrogated brain frontal cortex regions in postmortem patients who succumbed to severe COVID-19 and observed increased accumulation of senescent cells as compared to age-matched control brains from non-COVID-affected individuals. Moreover, we show that exposure of human brain organoids to SARS-CoV-2 evoked cellular senescence, and that spatial transcriptomic sequencing of virus-induced senescent cells identified a unique SARS-CoV-2 variant-specific inflammatory signature that is different from endogenous naturally-emerging senescent cells. Importantly, following SARS-CoV-2 infection of human brain organoids, treatment with senolytics blocked viral retention and prevented the emergence of senescent corticothalamic and GABAergic neurons. Furthermore, we demonstrate in human ACE2 overexpressing mice that senolytic treatment ameliorates COVID-19 brain pathology following infection with SARS-CoV-2. In vivo treatment with senolytics improved SARS-CoV-2 clinical phenotype and survival, alleviated brain senescence and reactive astrogliosis, promoted survival of dopaminergic neurons, and reduced viral and senescence-associated secretory phenotype gene expression in the brain. Collectively, our findings demonstrate SARS-CoV-2 can trigger cellular senescence in the brain, and that senolytic therapy mitigates senescence-driven brain aging and multiple neuropathological sequelae caused by neurotropic viruses, including SARS-CoV-2.

neuroscience↗

bioRxiv2022

An alpaca-derived nanobody neutralizes the SARS-CoV-2 omicron variant

The SARS-CoV2 Omicron variant sub-lineages spread rapidly through the world, mostly due to their immune-evasive properties. This has put a significant part of the population at risk for severe disease and underscores the need for anti-SARS-CoV-2 agents that are effective against emergent strains in vulnerable patients. Camelid nanobodies are attractive therapeutic candidates due to their high stability, ease of large-scale production and potential for delivery via inhalation. Here, we characterize the RBD-specific nanobody W25, which we previously isolated from an alpaca, and show superior neutralization activity towards Omicron lineage BA.1 in comparison to all other SARS-CoV2 variants. Structure analysis of W25 in complex with the SARS-CoV2 spike surface glycoprotein shows that W25 engages an RBD epitope not covered by any of the antibodies previously approved for emergency use. Furthermore, we show that W25 also binds the spike protein from the emerging, more infectious Omicron BA.2 lineage with picomolar affinity. In vivo evaluation of W25 prophylactic and therapeutic treatments across multiple SARS-CoV-2 variant infection models, together with W25 biodistribution analysis in mice, demonstrates favorable pre-clinical properties. Together, these data endorse prioritization of W25 for further clinical development.

microbiology↗

bioRxiv2022

The molecular mechanism of chloramphenicol and thiamphenicol resistance mediated by a novel oxidase CmO in Sphingomonadaceae

Antibiotic resistance mediated by bacterial enzyme inactivation plays a mysterious and crucial role for antibiotic degradation and selection pressure reduction in the environment. The enzymatic inactivation of the antibiotic chloramphenicol (CAP) involves nitro reduction, amide bond hydrolysis and acetylation modification. However, the molecular mechanism of enzymatic oxidation of CAP remains unknown. Here, a novel oxidase gene cmO was identified and confirmed biochemically to catalyze the resistance process through the oxidative inactivation at the side chain C-3 position of CAP and thiamphenicol (TAP) in Sphingomonadaceae. The oxidase CmO is highly conservative in Sphingomonadaceae and shares the highest amino acid homology of 41.05% with the biochemically identified glucose methanol choline (GMC) oxidoreductases. Molecular docking and site-directed mutagenesis analyses demonstrated that CAP was anchored inside the protein pocket of CmO with the hydrogen bonding of key residues glycine (G)99, asparagine (N)518, methionine (M)474 and tyrosine (Y)380. CAP sensitivity test demonstrated that the acetyltransferase and CmO showed higher resistance to CAP as compared with the amide bond-hydrolyzing esterase and nitroreductase. This study provides a better theoretical basis and a novel diagnostic gene for understanding and assessing the fate and resistance risk of CAP and TAP in the environment. ImportanceRising levels of antibiotic resistance undermines ecological and human health as a result of indiscriminate usage of antibiotics. Various resistance mechanisms have been revealed, for instance genes encoding proteins that degrade antibiotics, yet requiring further exploration. In this study, we reported a novel gene encoding an oxidase involved in the inactivation of typical amphenicol antibiotics (chloramphenicol and thiamphenicol), and the molecular mechanism was elucidated. The observation provides novel data to understand capabilities of bacteria to tackle antibiotic stress and suggests complex function of enzymes in the context of antibiotic resistance development and antibiotics removal. The reported gene can be further employed as an indicator to monitor amphenicols fate in the environment, benefiting the risk assessment in this era of antibiotic resistance.

microbiology↗

bioRxiv2022

Genomic alterations drive brain metastases formation in colorectal cancer: The role of IRS2

Colorectal cancer (CRC) is currently the fourth leading etiology of brain metastasis (BM). Yet, mechanisms supporting the formation of CRC BM are mostly unknown. In order to identify drivers that lead to tropism and adaptation of CRC cells to the brain environment, we analyzed an extensive genomic database, consisting of over 36,000 human CRC primary and metastasis samples. Several genomic alterations specific for BM were noted, among them increased prevalence of insulin receptor substrate 2 (IRS2) amplification, observed in 7.6% of BM, compared to only 2.9% of primary tumors or other metastatic sites (p<7E-05). This observation was validated by Immunohistochemistry studies of human clinical samples, showing increased expression of IRS2 protein in BM. IRS2 is a cytoplasmic adaptor mediating effects of insulin and IGF-1 receptors and is involved in more aggressive behavior of different cancer types. In order to study the ability of IRS2 to promote growth of CRC cells under brain microenvironment conditions, we employed an in vitro system consisting of cultured human astrocytes or their conditioned media. Indeed, IRS2-overexpressed CRC cells survived better and formed larger 3D spheres when grown in brain-mimicking conditions, while IRS2-silenced CRC cells showed a mirror image. Similarly, In vivo studies, using intracranial CRC BM mouse model, demonstrated that IRS2-overexpressed cells generated larger brain lesions, while silencing IRS2 dramatically decreased tumor outgrowth and extended survival. Transcriptomic analysis revealed enrichment of oxidative phosphorylation (OXPHOS) and Wnt/{beta}-catenin pathways by IRS2. Indeed, IRS2-expressing cells showed increased mitochondrial activity and glycolysis-independent viability. Furthermore, IRS2-expressing cells had increased {beta}-catenin transcriptional activity, and either {beta}-catenin inhibition or IRS2 inhibition in IRS2-expressing cells decreased their viability, {beta}-catenin transcriptional activity, and mitochondrial activity. These data suggest involvement of IRS2 in modulating OXPHOS through {beta}-catenin. Exploiting this mechanism as a potential vulnerability allowed us to develop novel treatment strategies against CRC BM. NT219 is a novel IRS1/2 inhibitor already being tested in clinical trials. Treatment of mice harboring CRC BM with NT219 and 5-flourouracil reduced tumor growth and prolonged mice survival. These data reveal, for the first time, the unique genomic profile of CRC BM and imply the IRS2 role in promoting CRC BM. These effects may be mediated, at least in part, by modulation of the {beta}-catenin and OXPHOS pathway. These findings may pave the way for clinical trials evaluation this novel IRS2-based strategy for the treatment of CRC BM. Accession no GSE203017 and here is the link: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE203017

cancer biology↗

bioRxiv2022

Role of Calcitonin Gene-Related Peptide (CGRP) in Auditory, Static, and Dynamic Imbalance Behaviors: Implications for Vestibular Migraine

Migraine is a severe and chronic neurological disorder that affects [~]18% of people worldwide, the majority being female (3:1). It is characterized by recurrent, debilitating headaches and heightened sensory sensitivities. People with migraine may develop vestibular migraine (VM), characterized by a heightened motion sensitivity and preponderance for spontaneous vertigo attacks and balance problems such as postural instability. Calcitonin gene-related peptide (CGRP) is implicated in migraine and is believed to act on brain meninges or in subcortical central nervous system (CNS) structures, and CGRP-based antagonists have shown efficacy for migraine treatment. CGRP also signals at efferent synapses of the cochlea and vestibular end organs, but it is unclear if exogenous CGRP can modulate inner ear function at the end organ level and cause heightened behavioral responses consistent with VM. We tested if intraperitoneally (IP) delivered CGRP to wildtype mice can modulate end organ potentials to sound [via auditory brainstem responses (ABRs)] and jerk stimuli [via vestibular sensory evoked potentials (VsEPs)]. We also assessed behavioral measures of phonophobia [acoustic startle reflex (ASR)] and static imbalance [postural sway-center of pressure (CoP)] after IP CGRP, and observed female mice exhibited heightened sensitivities to IP CGRP in all assays. Male mice showed similar auditory sensitivity and end organ effects to CGRP, but systemic CGRP did not modify male postural sway as it did in females. In conclusion, we show that intraperitoneally delivered CGRP affects ABRs and VsEPs, and elicits behaviors suggestive of auditory hypersensitivity and postural instability in mice related to the phonophobia and postural instability seen in VM patients. Significance StatementCalcitonin Gene-Related Peptide (CGRP) has been implicated in migraine, and CGRP-based therapeutics have shown efficacy in the treatment of migraine headaches. CGRP is also present in efferent synapses of the inner ear, so we questioned if increases in systemic CGRP can act directly on inner ear end organs and modify corresponding behavioral responses. In this study, we determined systemic CGRP changes cochlear and vestibular end organ potentials and produces migraine behaviors similar to phonophobia and postural control deficits. Peripheral changes in auditory and vestibular compound action potentials following systemic CGRP administration suggest CGRP can act directly on the inner ear, which provides one site of action for CGRPs involvement in hypersensitivity to sound and movement in migraine.

neuroscience↗

bioRxiv2022

Striosomes constrain locomotor vigor with respect to an innate valence differential

Survival demands that safe and unsafe contexts are met with different locomotor profiles, yet whether striatal microcircuitry links contextual valence to spontaneous locomotor vigor is unresolved. Here we test for striosome contributions to spontaneous locomotion using ablation, calcium imaging and chemogenetics in the context of a modified Light/Dark box test. We found that locomotor speed reflects the unlearned, external valence differential present in this test, and that striosomes gate valence-oriented speed selection. Our data suggest that striosomes dampen motor vigor associated with lesser valence, or elevated anxiety. HighlightsO_LIMice explore the light and dark zones in Light/Dark box with different walk speed C_LIO_LIStriosome ablation reduces restful slowing and elevates speed relative to zone C_LIO_LIMany striosome neurons exhibit light-zone preference and speed related activity C_LIO_LIStriosome enhancement slows mice and blunts zone discrimination by speed C_LI

neuroscience↗

bioRxiv2022

Comparative genomic and crystal structure analyses identify a collagen glucosyltransferase from Acanthamoeba Polyphaga Mimivirus

Humans and Acanthamoeba Polyphaga Mimivirus share numerous homologous genes, including collagens and collagen-modifying enzymes. To explore the homology, we performed a genome-wide comparison between human and mimivirus using DELTA-BLAST (Domain Enhanced Lookup Time Accelerated BLAST) and identified 52 new mimiviral proteins that are homologous with human proteins. To gain functional insights into mimiviral proteins, their human protein homologs were organized into Gene Ontology (GO) and REACTOME pathways to build a functional network. Collagen and collagen-modifying enzymes form the largest subnetwork with most nodes. Further analysis of this subnetwork identified a putative collagen glycosyltransferase R699. Protein expression test suggested that R699 is highly expressed in E coli, unlike the human collagen-modifying enzymes. Enzymatic activity assays showed that R699 catalyzes the conversion of unique galactosylhydroxylysine within the GXXXUG motif (U=galactosylhydroxylysine) to glucosylgalactosylhydroxylysine on collagen using uridine diphosphate glucose (UDP-Glc) as a sugar donor, suggesting R699 is a mimiviral collagen galactosylhydroxylysyl glucosyltransferase (GGT) with defined substrate specificity. Structural study of R699 produced the first crystal structure of a collagen GGT with a visible UDP-Glc. Sugar moiety of the UDP-Glc resides in a previously unrecognized pocket. Mn2+ coordination and nucleoside-diphosphate binding site are conserved among GGT family members and critical for R699s collagen GGT activity. To facilitate further analysis of human and mimiviral homologous proteins, we presented an interactive and searchable genome-wide comparison website for quickly browsing human and Acanthamoeba Polyphaga Mimivirus homologs, which is available at RRID Resource ID: SCR_022140 or https://guolab.shinyapps.io/app-mimivirus-publication/.

biochemistry↗