Biology subjects

Sharma, M.

Publications and source records attributed to Sharma, M..

At least 91 records · Page 5Linked to original sources

bioRxiv2023

Insecticidal Effects of Datura Species against Major Agricultural Pests

Insecticides derived from plants provide environmentally friendly and sustainable options as alternatives to synthetic chemicals. This investigation delves into the insecticidal capabilities of two distinct Datura species, namely, Datura alba and Datura stramonium, in combatting significant pests such as Spodoptera litura, Bemesia tabaci, and Callosobruchus maculatus. Datura plants have a well-documented history of medicinal use and are recognized for their abundant Tropane alkaloid content, which acts as an innate defense mechanism against pests. Hence, the current investigation involved the extraction of chemical compounds from the leaves, flowers, seeds, and roots of both Datura stramonium and Datura alba. Subsequently, these extracts were assessed for efficacy using Spodoptera litura larvae, Bemesia tabaci, and Callosobruchus maculatus in bioassays. The larvicidal experiments encompassed a range of concentrations (3%, 5%, 10%), with larval mortality being documented at multiple time intervals: 6, 12, 24, 48, and 72 hours. The findings from our investigation uncover the notable insecticidal attributes of root, leaf, flower, and seed extracts from both Datura alba and Datura stramonium against these larvae. These extracts demonstrated distinct mortality rates at various concentrations and exposure durations. This comprehensive analysis imparts crucial knowledge regarding the insecticidal qualities of Datura species and their prospective contributions to sustainable pest control practices. The observed effectiveness of these plant extracts against a spectrum of significant pests hints at their potential as ecological alternatives within integrated pest management strategies.

plant biology↗

bioRxiv2023

A conserved ESCRT-II-like protein participates in the biogenesis and maintenance of thylakoid membranes

Thylakoids are membrane-bound compartments located in cyanobacteria and chloroplasts of plants and algae. They play an indispensable role in the light-driven reactions that enable photosynthetic organisms to convert water and carbon dioxide into oxygen and sugars. The biogenesis and maintenance of thylakoid membranes is a critical yet underappreciated area of research. One of the few known critical regulators of this process, VIPP1 (Vesicle-Inducing Protein in Plastids 1), was recently shown to be structurally similar to ESCRT-III proteins -- the first evidence for ESCRT-like (Endosomal Sorting Complex Required for Transport) machinery in chloroplasts. Here, we used an affinity purification approach in two distantly related photosynthetic eukaryotes, the green alga Chlamydomonas reinhardtii and the plant Arabidopsis thaliana, to discover proteins that interact with VIPP1. Among several newly identified proteins, we focused on a highly conserved but uncharacterized protein (VIPP1-Associated protein 1, VIA1) that robustly interacts with VIPP1 in both systems. VIA1 is predicted to contain a winged-helix domain, a characteristic feature of ESCRT-II proteins that mediates the interaction with ESCRT-III proteins. The absence of VIA1 causes thylakoid swelling upon exposure to high light in Chlamydomonas and defective thylakoid biogenesis in the newly emerging leaf tissue in Arabidopsis, thereby delaying chloroplast development in this tissue. We propose that VIA1 is part of a previously unrecognized chloroplast ESCRT-like system that plays a critical role in forming, remodeling, and repairing photosynthetic membranes. Significance StatementThylakoid membranes are essential for photosynthesis, yet their biogenesis and maintenance are poorly understood. Of the few known proteins involved in these processes, VIPP1 stands out due to its similarity to ESCRT-III, an integral component of the ESCRT machinery that is responsible for membrane remodeling and trafficking in the cytoplasm of eukaryotes. Here we report the discovery of VIA1, a conserved protein that interacts with VIPP1 and participates in thylakoid biogenesis and remodeling in two distantly related photosynthetic organisms. Because VIA1 contains a predicted winged-helix domain, a hallmark feature of ESCRT-II proteins that mediates the interaction with ESCRT-III proteins, our data support the hypothesis that universal, mechanistic principles govern membrane remodeling across all living organisms.

plant biology↗

bioRxiv2023

Notch3 deletion regulates HIV-1 gene expression and systemic inflammation to ameliorate chronic kidney disease

Antiretroviral therapy (ART) has decreased HIV-1 associated morbidity. However, despite ART, immune cells remain latently infected and slowly release viral proteins, leading to chronic inflammation and HIV-1 associated comorbidities. New strategies are needed to target viral proteins and inflammation. We found activation of Notch3 in several renal cells of the HIV-1 mouse model (HIV-Tg26) and in patients with HIV associated Nephropathy. We hypothesized that targeting Notch3 activation constitutes an effective therapy for HIV-related chronic kidney diseases (HIV-CKD). We generated HIV-Tg26 mice with Notch3 knocked out (Tg-N3KO). Compared to HIV-Tg26 mice at 3 months, HIV-Tg-N3KO mice showed a marked reduction in renal injury, skin lesions and mortality rate. Bulk RNA sequencing revealed that N3KO not only reduced renal infiltrating cells but significantly reduced the expression of HIV genes. Moreover, Notch3 activated the HIV-promoter and induction of HIV-1 resulted in increased Notch3 activation indicating a feedback mechanism. Further, bone marrow derived macrophages (BMDMs) from HIV-Tg26 mice showed activation of Notch3 indicating systemic effects. Consistent with that, systemic levels of TNF-, MCP-1 and other inflammatory chemokines and cytokines were reduced in Tg-N3KO mice. Thus, Notch3 inhibition/deletion has a dual therapeutic effect in HIV-CKD and may extend to other HIV-related pathologies.

molecular biology↗

bioRxiv2023

Plasmodium falciparum Raf kinase inhibitor is a lipid binding protein that interacts with CDPK1 and regulates its activity in asexual blood stage.

Raf Kinase Inhibitor Protein (RKIP) is an important regulator of MAPK signaling pathway in multicellular eukaryotes. Plasmodium falciparum RKIP (PfRKIP) is a putative phosphatidylethanolamine binding protein (PEBP) that shares limited similarity with Homo sapiens RKIP (HsRKIP). Interestingly, critical components of MAPK pathway are not expressed in malaria parasite and the physiological function of PfRKIP remains unknown. PfRKIP is expressed throughout the asexual schizogony with maximum expression in late schizonts. Interestingly, PfRKIP and HsRKIP show pH dependent differential interaction profiles with various lipids. At physiological pH, PfRKIP show interaction with PE and lipids containing phosphorylated phosphatidylinositol group; however, HsRKIP show no interaction under the same conditions. Mutation of conserved residues in the PEBP domain of PfRKIP decreases its interaction with PI(3)P. Furthermore, our results suggest that PfRKIP leads to increase in the autophosphorylation of PfCDPK1 that leads to transphosphorylation of substrates by PfCDPK1. Using various in vitro and in vivo experiments we have demonstrated the interaction of PfRKIP with PfCDPK1 and have also identified key residues in PfRKIP that play important role in this interaction. Interestingly, locostatin, a specific inhibitor of mammalian RKIP increased the interaction of PfRKIP with PfCDPK1 that perhaps leads to the sequestration of PfCDPK1 in a heterodimeric complex. Importantly, treatment of malaria parasite with locostatin shows dose dependent inhibition of parasite growth. This study suggests that specific inhibitors that modify PfRKIP leading to increase in its interaction with PfCDPK1 may be designed and explored as novel anti-malarial compounds to inhibit malaria parasite growth.

biochemistry↗

bioRxiv2023

Peripheral linker mediates ACP's recognition of DH and stabilizes Mycobacterium tuberculosis FAS-I

1Incomplete structural details of Mycobacterium tuberculosis (Mtb) fatty acid synthase-I (FAS-I) at near-atomic resolution have limited our understanding of the shuttling mechanism of its mobile acyl carrier protein (ACP). Here, we have performed atomistic molecular dynamics simulation of Mtb FAS- I with a homology-modelled structure of ACP stalled at dehydratase (DH), and identified key residues that mediate anchoring of the recognition helix of ACP near DH. The observed distance between catalytic residues of ACP and DH agrees with that reported for fungal FAS-I. Further, the conformation of the peripheral linker is found to be crucial in stabilizing ACP near DH. Correlated inter-domain motion is observed between DH, enoyl reductase (ER) and malonyl/palmitoyl transferase (MPT); consistent with prior experimental reports of fungal and Mtb FAS-I.

biophysics↗

bioRxiv2023

Human iPSC 4R tauopathy model uncovers modifiers of tau propagation

Tauopathies are age-associated neurodegenerative diseases whose mechanistic underpinnings remain elusive, partially due to lack of appropriate human models. Current human induced pluripotent stem cell (hiPSC)-derived neurons express very low levels of 4-repeat (4R)-tau isoforms that are normally expressed in adult brain. Here, we engineered new iPSC lines to express 4R-tau and 4R-tau carrying the P301S MAPT mutation when differentiated into neurons. 4R-P301S neurons display progressive Tau inclusions upon seeding with Tau fibrils and recapitulate features of tauopathy phenotypes, including shared transcriptomic signatures, autophagic body accumulation, and impaired neuronal activity. A CRISPRi screen of genes associated with Tau pathobiology identified over 500 genetic modifiers of Tau-seeding-induced Tau propagation, including retromer VPS29 and the UFMylation cascade as top modifiers. In AD brains, the UFMylation cascade is altered in neurofibrillary-tangle-bearing neurons. Inhibiting the UFMylation cascade suppressed seeding-induced Tau propagation. This model provides a powerful platform to identify novel therapeutic strategies for 4R tauopathy.

neuroscience↗

bioRxiv2023

Metagenomic survey of antimicrobial resistance (AMR) in Maryland surface waters differentiated by high and low human impact

In alignment with the One Health paradigm, surface waters are being evaluated as a modality to better understand baseline antimicrobial resistance (AMR) across the environment to supplement existing AMR monitoring in pathogens associated with humans, foods, and animals. Here, we use metagenomic and quasimetagenomic sequence data to describe AMR in Maryland surface waters from developed (high human impact) and natural (low human impact) classifications by the National Land Cover Database (NLCD). Critically important {beta}-lactamase genes were observed in twice as many high human impact zones. All data are available under BioProject PRJNA79347. https://www.ncbi.nlm.nih.gov/bioproject/794347

microbiology↗

bioRxiv2023

Transcriptional landscape of DTP-DTEP transition reveals DUSP6 as a driver of HER2 inhibitor tolerance via Neuregulin/HER3 axis

The mechanisms promoting re-growth of dormant cancer cells under continuous tyrosine kinase inhibitor (TKI) therapy are poorly understood. Here we present transcriptional profiling of HER2+ breast cancer cells treated continuously with HER2 TKI (HER2i) therapy for 9 months. The data reveals specific gene regulatory programs associated with transition from dormant drug tolerant persister cells (DTPs) to proliferating DTEP (drug tolerant expanding persister) cells and eventually long-term resistance. Focusing on yet poorly understood phosphatases as determinants of therapy tolerance, expression of dual-specificity phosphatase DUSP6 was found inhibited in DTPs, but strongly induced upon re-growth of DTEPs. DUSP6 overexpression conferred apoptosis resistance whereas its pharmacological blockade prevented DTEP development under HER2i therapy. The DUSP6-driven HER2i tolerance was mediated by activation of neuregulin-HER3 axis, and consistent with the role of HER3 in widespread therapy tolerance, DUSP6 targeting also synergized with clinically used HER2i combination therapies. In vivo, pharmacological DUSP6 targeting induced synthetic lethal effect with HER2i in independent tumor models, and its genetic targeting reduced tumor growth in orthotopic brain metastasis model. Collectively this work provides first transcriptional landscape of DTP-DTEP transition under TKI therapy, and identify DUSP6 as a novel candidate therapy target to overcome widespread HER3-driven therapy resistance.

cancer biology↗

bioRxiv2023

Correlation between antibacterial activity of two Artemisia sp. extracts and their plant characteristics

The present study evaluated the potential antibacterial activity of Artemisia absinthium L. and Artemisia herba-alba Asso. extracts through different organic and aqueous solvents. The tested bacteria were pathogenic types; Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella enterica and Staphylococcus aureus. There were different affinities for the studied organic solvents besides aqueous one. The comparative study was accomplished with comparing to the morphological, anatomical and palynological characters. The similarity parameter is obtained. ANOVA test analyzed MIC values for both plant extracts. Pearson Correlation Coefficients were determined for all both plant traits. MIC and MBC values were confirmed on using butanol and diethyl ether extracts besides butanol and chloroform extracts for Artemisia absinthium L. and Artemisia hera alba Asso against tested pathogenic bacteria respectively as an alternative natural antibacterial inhibitor agent.

microbiology↗

bioRxiv2023

Connexin 43 mediated collective cell migration is independent of Golgi orientation

Cell migration is vital for multiple physiological functions and is involved in the metastatic dissemination of tumour cells in various cancers. For effective directional migration, cells often reorient their secretory traffic towards the leading edge by reorienting the Golgi apparatus. However, conflicting results on the positioning of the Golgi relative to the migrating cell raise questions about its regulation. Herein, we address the role of gap junction protein Connexin 43, which connects cells allowing the direct exchange of molecules and also controls the distribution of microtubules. We utilized HeLa WT (wild-type cells lacking Connexin 43) and HeLa 43 cells (stably expressing Connexin 43). We found that functional Connexin 43 channels affected Golgi morphology and reduced the ability of reorientation of Golgi (towards the leading edge) during cell migration. Although Connexin 43 also reduced migration velocity, the front displayed enhanced coherence in movement, implying an augmented collective nature of migration compared to HeLa WT cells lacking the cell-cell connectivity evidenced in HeLa 43. The increase in vimentin and basal actin in HeLa 43 shows that Connexin 43 expression alters the cytoskeleton. Non-invasive measurement of basal membrane height fluctuations revealed that HeLa 43 had a lower membrane tension and a more uniform intra- and inter-cellular distribution than HeLa WT, similar to their coherence in migration. We, therefore, propose that the reduced Golgi reorientation in HeLa 43 might be linked to lesser dependence on directed secretory trafficking, which is believed to be required to buffer the increasing tension caused by migration.

biophysics↗

bioRxiv2023

Reservoir Dogs: Consequences of variable contact network structures for disease spread in free-ranging dogs

The risk of disease spread is contingent on not only the biological properties of causal agents, such as viruses and bacteria, but also the socio-ecological context of the outbreak. Therefore, researchers need to incorporate the variation in animal-animal interactions in models of disease spread. Much research has focused on how ecological factors (seasonality, mating systems) can influence the variation in animal interactions, but heterogeneity in interactions may arise due to human action, and this has received little attention. We hypothesised that social-mediated differences in the landscape can have consequences for interactions for free-roaming dogs and consequently for disease spread. We used GPS collared data from 31 free-ranging dogs present along a farm-village gradient to build social contact networks to examine differences in interactions. Additionally, we simulated scenarios of rabies infection of two types - dumb and furious - on the contact network structure of village and farm dogs. We found significant differences in the node degree between village and farm contact networks, but the node betweenness was similar. Our simulations showed that infections arising in village dogs are likely to spread to that network, but infections arising in farm dogs get are less likely to spread. Interestingly, this was independent of the type of rabies infection. We discuss our results in light of control strategies for managing rabies in the tropics.

ecology↗

bioRxiv2023

Sulfolactaldehyde dehydrogenase of Rhizobium leguminosarum: Kinetic and structural analysis

Sulfolactate (SL) is a short-chain organosulfonate that is an important reservoir of sulfur in the biosphere. SL is produced by oxidation of sulfolactaldehyde (SLA), which in turn derives from sulfoglycolysis of the sulfosugar sulfoquinovose, or through oxidation of 2,3-dihydroxypropanesulfonate. Oxidation of SLA is catalyzed by SLA dehydrogenases belonging to the aldehyde dehydrogenase superfamily. We report that SLA dehydrogenase RlGabD from the sulfoglycolytic bacterium Rhizobium leguminsarum SRDI565 can use both NAD+ and NADP+ as cofactor to oxidize SLA, and indicatively operates through a rapid equilibrium ordered mechanism. We report the cryo-EM structure of RlGabD bound to NADH, revealing a tetrameric quaternary structure and supporting proposal of organosulfonate binding residues in the active site, and a catalytic mechanism. Sequence based homology searches identified SLA dehydrogenase homologs in a range of putative sulfoglycolytic gene clusters in bacteria predominantly from the phyla Actinobacteria, Firmicutes, and Proteobacteria. This work provides a structural and biochemical view of SLA dehydrogenases to complement our knowledge of SLA reductases, and provide detailed insights into a critical step in the organosulfur cycle. Graphical abstractSulfolactate is an important species in the biogeochemical sulfur cycle. Herein we report the 3D cryo-EM structure and kinetics of its biosynthetic enzyme, sulfolactaldehyde dehydrogenase. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/532361v4_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@1f3d1d3org.highwire.dtl.DTLVardef@548615org.highwire.dtl.DTLVardef@12efc0eorg.highwire.dtl.DTLVardef@1a6145c_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2023

Novel Evoked Synaptic Activity Potentials (ESAPs) elicited by Spinal Cord Stimulation

Spinal cord stimulation (SCS) evokes fast epidural Evoked Compound Action Potential (ECAPs) that represent activity of dorsal column axons, but not necessarily a spinal circuit response. Using a multimodal approach, we identified and characterized a delayed and slower potential evoked by SCS that reflects synaptic activity within the spinal cord. Anesthetized female Sprague Dawley rats were implanted with an epidural SCS lead, epidural motor cortex stimulation electrodes, an epidural spinal cord recoding lead, an intraspinal penetrating recording electrode array, and intramuscular electromyography (EMG) electrodes in the hindlimb and back. We stimulated the motor cortex or the epidural spinal cord and recorded epidural, intraspinal, and EMG responses. SCS pulses produced characteristic propagating ECAPs (composed of P1, N1, and P2 waves with latencies <2 ms) and an additional wave ("S1") starting after the N2. We verified the S1-wave was not a stimulation artifact and was not a reflection of hindlimb/back EMG. The S1-wave has a distinct stimulation-intensity dose response and spatial profile compared to ECAPs. CNQX (a selective competitive antagonist of AMPA receptors) significantly diminished the S1-wave, but not ECAPs. Furthermore, cortical stimulation, which did not evoke ECAPs, produced epidurally detectable and CNQX-sensitive responses at the same spinal sites, confirming epidural recording of an evoked synaptic response. Finally, applying 50 Hz SCS resulted in dampening of ESAPs, but not ECAPs. Therefore, we hypothesize that the S1-wave is synaptic in origin, and we term the S1-wave type responses: Evoked Synaptic Activity Potentials (ESAPs). The identification and characterization of epidurally recorded ESAPs from the dorsal horn may elucidate SCS mechanisms. Significance StatementSpinal cord stimulation (SCS) is an established treatment for chronic pain and has applications to other disorders and neurorehabilitation. Notwithstanding decades of trials and research, questions remain about SCS mechanisms of action - and indicators thereof. Recent technological developments have enabled the detection of Evoked Compound Action Potential (ECAPs) - reflecting synchronous activity of the dorsal column axons activated by SCS. However, ECAP is not a direct measure of sensory processing in the dorsal horn. Here, we identify and characterize a novel electrophysiological signal that is evoked and detectable by epidural SCS electrodes and reflects spinal synaptic currents. This new signal, termed an Evoked Synaptic Activity Potential (ESAP), is thus a novel means with which to interrogate spinal gray matter circuits during SCS.

neuroscience↗

bioRxiv2023

Metabolomics reveals nucleoside analogs for regulating mucosal-associated invariant T cell responses

Although mucosal-associated invariant T (MAIT) cells recognize riboflavin-like metabolites from Gram-negative bacteria, MAIT cell stimulation by broad bacterial families and mammalian cells suggests the existence of novel ligands from different biological sources. Here we established a comparative platform of functional metabolomics and used Mycobacterium tuberculosis as a model to characterize novel metabolites for MAIT cell activation. We extracted and fractionated small metabolites of M. tuberculosis using high-performance liquid chromatography, showing a different MAIT cell stimulation pattern of M. tuberculosis metabolite fractions in comparison with Escherichia coli fractions. Mass profiling predicted multiple nucleoside analogs enriched in a biologically active fraction of M. tuberculosis. Whereas the synthetic forms of these predicted M. tuberculosis nucleosides were unavailable, structural-based autodocking of analogous nucleosides conserved in mammals supported potential binding with MR1 protein. Indeed, functional assays of these conserved nucleosides demonstrated guanosine as a stimulator and deoxyformyluridine as an inhibitor of MAIT cell activation. Identification of bioactive nucleoside metabolites broadly conserved in bacterial and mammalian systems will facilitate an understanding of the regulatory roles of MAIT cells in infectious and inflammatory conditions.

immunology↗

bioRxiv2023

Deciphering the phenotypic heterogeneity and drug response in cancer cells using genome-wide activity and interaction of chromatin domains.

The effect of co-localization of genes in the topologically associated domains (TADs) and their activity as a regulatory unit in cancer samples and cells, together with drug-response, needs comprehensive analysis. Here, we analyzed the activity of TADs using cancer-cell transcriptomes along with chromatin-interaction and epigenome profiles to understand their relationship with drug-response. Our analysis of 819 cancer cell-line transcriptomes revealed that their response to multiple drugs was more correlated with the activity of individual TADs than genes. Applying our approach to 9014 cancer patients data (20 different cancer types) also revealed a higher association between survival and the activity of thousands of individual TADs in comparison to their genes. CRISPR-mediated knock-out of regulatory sites inside a TAD associated with cisplatin-response of oral cancer cells and discovery of primate-specific gain of synteny of genes within a TAD containing EGFR gene and its contribution towards cancer malignancy demonstrate greater utility of TAD-activity based analysis.

cancer biology↗

bioRxiv2022

Intragastric administration of low-dose rotenone post-colitis exacerbates damage to the nigrostriatal dopaminergic system in Parkinson's disease: The pace accelerates even more

BackgroundThe contribution of gastrointestinal (GI) inflammation and local exposure to neurotoxins in the gut offers the most in-depth explanation of Parkinsons disease (PD) etiopathogenesis through abnormal accumulation and spreading of alpha-synuclein (-syn) aggregates from the gut to the brain. ObjectivesThis study was designed to investigate whether dextran sodium sulfate (DSS)-mediated colitis may have lasting effects on dopaminergic pathways in the brain and whether or not colitis exacerbated susceptibility to later exposure to the neurotoxin rotenone. MethodsTo induce chronic colitis, 10 months old C57BL/6 mice were pre-exposed to 3 cycles of 7 days of 1% (w/v) DSS administration in drinking water followed by 14 days of regular drinking water. After colitis-induction, animals received a low dose of intragastric rotenone for the next 8 weeks, followed by testing for Parkinsonian behavior and GI phenotypes of inflammation. At the end of the 8th week after colitis, colon, brain stem, and midbrain tissue were isolated and analyzed for -syn, inflammatory markers, and dopaminergic neuronal loss. Gut microbial composition was assessed by 16S rRNA sequencing analysis. ResultsWe found that local rotenone exposure for 8 weeks did not affect colitis severity and colonic tight junction(TJ) protein expression (ZO-1, Occludin, and Claudin-1). On the other hand, we found that while eight weeks of chronic rotenone administration led to an increase in inflammatory markers, the presence of pre-existing colitis resulted in a considerable change in gut microbiota composition and a decrease in TJs protein expression. In addition, the administration of rotenone in mice post-colitis caused gastrointestinal function impairment and poor behavioral performances. Itworsened rotenone-induced -syn pathology in the colon, which extended upward and resulted in severe dopaminergic neuron loss and significant astroglia activation in the dorsal motor nucleus of the vagus (DMV), locus coeruleus, substantia nigra as well as in striatum. Interestingly, in the case of rotenone alone, we found that -syn induced ChAT+ neuronal death is restricted to the DMV. These findings indicate that long-term rotenone exposure in conjunction with early inflammatory intestinal milieu exacerbates the progression of -syn pathology and aggravates neurodegeneration in the intragastric mouse PD model. ConclusionsThis work provides detailed insight into the involvement of GI inflammation triggered after a neurotoxic insult in the colon and explores their potential to impact central dopaminergic degeneration in PD. This way, we can identify potential therapeutic targets that stop the enteric inflammatory processes involved in progressing PD. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=170 HEIGHT=200 SRC="FIGDIR/small/521569v1_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@e0b5a4org.highwire.dtl.DTLVardef@b556c0org.highwire.dtl.DTLVardef@1526d27org.highwire.dtl.DTLVardef@7c506f_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LILow-dose intragastric rotenone post-colitis aggravates gastrointestinal dysfunction and accelerates the onset of motor impairment. C_LIO_LILow-dose intragastric rotenone did not alter colitis clinical and histological aspects. C_LIO_LILow-dose intragastric rotenone post-colitis exacerbated the progression of -syn pathology from the GI tract to the brain, leading in central dopaminergic neuronal degeneration. C_LI

neuroscience↗

bioRxiv2022

The chemorepellent, SLIT2, bolsters innate immunity against Staphylococcus aureus

Neutrophils are essential for host defense against Staphylococcus aureus (S. aureus). The neuro-repellent, SLIT2, potently inhibits neutrophil chemotaxis, and might therefore be expected to impair antibacterial responses. We report here that, unexpectedly, neutrophils exposed to the N-terminal SLIT2 (N-SLIT2) fragment kill extracellular S. aureus more efficiently. N-SLIT2 amplifies reactive oxygen species production in response to the bacteria by activating p38 mitogen-activated protein kinase that in turn phosphorylates NCF1, an essential subunit of the NADPH oxidase complex. N-SLIT2 also enhances exocytosis of secondary granules. In a murine model of S. aureus skin and soft tissue infection (SSTI), local SLIT2 levels fall initially but increase subsequently, peaking {approx} 3 days after infection. Of note, neutralization of endogenous SLIT2 worsens SSTI. Temporal fluctuations in tissue SLIT2 levels may promote neutrophil recruitment and retention at the infection site and hasten bacterial clearance by augmenting neutrophil oxidative burst and degranulation. Collectively, these actions of SLIT2 coordinate innate immune responses to limit susceptibility to S. aureus. One-sentence summarySLIT2, a prototypic neuro-repellent, spatiotemporally coordinates host defense against Staphylococcus aureus infection.

cell biology↗

bioRxiv2022

Assembly mechanism of the AIM2 inflammasome sensorrevealed by single-molecule analysis

Pathogenic dsDNA prompts AIM2 (Absent In Melanoma 2) assembly leading to the formation of the inflammasome, a multimeric complex that triggers the inflammatory response. The recognition of foreign dsDNA involves AIM2 self-assembly concomitant with dsDNA binding. However, we lack mechanistic and kinetic information on the formation and propagation of the assembly, which can shed light on innate immunitys time response and specificity. Using correlative optical traps and fluorescence microscopy, we determine here the association and dissociation rates of the AIM2-DNA complex at the single-molecule level. We identify distinct mechanisms for oligomer growth via the binding of incoming AIM2 molecules to adjacent dsDNA or direct interaction with bound AIM2 assemblies, thus resembling primary and secondary nucleation processes. Through these mechanisms, AIM2 oligomers increase at least fourfold their size in seconds. Finally, our data indicate that single AIM2 molecules do not diffuse/scan along the DNA, suggesting that oligomerization depends on stochastic encounters with DNA and/or DNA-bound AIM2 molecules.

biophysics↗