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Agarwal, A.

Publications and source records attributed to Agarwal, A..

At least 55 records · Page 3Linked to original sources

TIVAN-indel: A computational framework for annotating and predicting noncoding regulatory small insertion and deletion

MotivationSmall insertion and deletion (sindel) of human genome has an important implication for human disease. One important mechanism for noncoding sindel to have an impact on human diseases and phenotypes is through the regulation of gene expression. Nevertheless, current sequencing technology may lack statistical power and resolution to pinpoint the causal sindel due to lower minor allele frequency or small effect. As an alternative solution, a supervised machine learning method can identify the otherwise missing causal sindels by predicting the regulatory potential of sindels directly. However, computational methods for annotating and predicting the regulatory sindels, especially in the noncoding regions, are underdeveloped. ResultsBy leveraging recognized sindels in cis-expression quantitative trait loci (cis-eQTLs) across 44 tissues and cell types in GTEx, and a compilation of both generic functional annotations and tissue/cell typespecific multi-omics features generated by a sequence-based deep learning model, we developed TIVAN-indel, which is an XGBoost-based supervised framework for scoring noncoding sindels based their potential to regulate the nearby gene expression. As a result, we demonstrate that TIVAN-indel achieves the best prediction performance in both cross-validation with-tissue prediction and independent cross-tissue evaluation. As an independent evaluation, we train TIVAN-indel from "Whole Blood" tissue in GTEx data and test the model using 15 immune cell types from an independent study DICE. Lastly, we perform an enrichment analysis for both recognized and predicted sindels in key regulatory regions such as chromatin interactions, open chromatin and histone modification sites, and find biologically meaningful enrichment patterns. Availability and implementationhttps://github.com/lichen-lab/TIVAN-indel Contactli.chen1@ufl.edu

bioinformatics↗

The transcriptional and epigenetic reprogramming mediated by chronic IL1β exposure drives self-renewal ability and myeloid priming in TET2 deficient stem and progenitor cells.

Clonal hematopoiesis (CH) increases the risk for the development of hematological malignancy and cardiovascular disease. IL1{beta} is elevated in patients with CH and its inhibition mitigates cardiovascular risk in murine models with Tet2 loss-of-function. How IL1{beta} alters population dynamics of hematopoietic cells upon Tet2 deletion (Tet2-KO) is not well understood. We demonstrated IL1{beta} expands Tet2-KO monocytes/macrophages, and long-term hematopoietic stem cells. IL1{beta} promoted myeloid bias over other lineages of Tet2-KO HSPCs coinciding with the failure to demethylate lineage-associated enhancer and transcription factor binding sites. IL1{beta} enhanced the self-renewal ability of Tet2-KO HSPCs by upregulating genes associated with self-renewal and by resisting the demethylation of binding sites of transcription factors promoting terminal differentiation. The IL1{beta}-mediated premalignant phenotype is suppressed by the IL1{beta} antagonist or deletion of the IL1 receptor-1, in vivo in aged mice. Our results demonstrate that targeting IL1 signaling could be an efficient early intervention strategy in preleukemic disorders. STATEMENT OF SIGNIFICANCEIL1{beta} promoted myeloid expansion and self-renewal capacity of TET2-null pre-leukemic cells. Lineage bias occurred early within progenitors towards pro-inflammatory macrophages. Genes specific to aging and with roles in promoting self-renewal capacity, and myeloid bias were upregulated. Hypermethylation occurred within lymphoid and erythroid lineage-specific regulatory elements. Targeting IL1R1 reduced aberrant myeloid bias and premalignant phenotype.

cancer biology↗

NAD(H) homeostasis is essential for host protection mediated by glycolytic myeloid cells in tuberculosis

Mycobacterium tuberculosis (Mtb) disrupts glycolytic flux in infected myeloid cells through an unclear mechanism. Flux through the glycolytic pathway in myeloid cells is inextricably linked to the availability of NAD+, which is maintained by NAD+ salvage and lactate metabolism. Using lung tissue from tuberculosis (TB) patients and myeloid deficient LDHA (LdhaLysM-/-) mice, we demonstrate that glycolysis in myeloid cells is essential for protective immunity in TB. Glycolytic myeloid cells are essential for the early recruitment of multiple classes of immune cells and the protective effects of IFN{gamma}. We identified NAD+ depletion as central to the glycolytic inhibition caused by Mtb. Lastly, we show that the NAD+ precursor nicotinamide exerts a host-directed, antimycobacterial effect, and that nicotinamide prophylaxis and treatment reduces Mtb lung burden in vivo. These findings provide new insight into how Mtb alters host metabolism through perturbation of NAD(H) homeostasis and reprogramming of glycolysis, highlighting this pathway as a potential therapeutic target.

microbiology↗

Norepinephrine regulates Ca2+ signals and fate of oligodendrocyte progenitor cells in the cortex

Oligodendrocyte precursor cells (OPCs) represent the most abundant group of proliferating cells in the adult central nervous system. OPCs serve as progenitors for oligodendrocyte (OLs) throughout the life, and contribute to developmental and adaptive myelination, and myelin repair during diseased state. OPCs make synaptic and extra-synaptic contacts with axons, and detect and respond to neuronal activity. How OPCs translate the information relayed by the neuronal activity into Ca2+ signals, which in turn influence their fate and survival, is less understood. We developed novel transgenic mouse lines expressing a cytosolic and membrane anchored variants of genetically encoded Ca2+ sensors (GCaMP6f or mGCaMP6s) in OPCs, performed 2-photon microscopy in the somatosensory cortex of the awake behaving mice, and simultaneously monitored intracellular Ca2+ signals and their cell-fate progression. We found Ca2+ signals in OPCs mainly occur within processes and confine to micrometer-size segments called Ca2+ microdomains. Microdomain Ca2+ signals enhanced in OPCs when mice engage in exploratory behavior. OPCs exhibit distinct Ca2+ signals while they proliferate to maintain their precursor pool or differentiate to generate new OL. When mice engaged in exploratory behavior, the cortical projections of noradrenergic neurons in locus coeruleus showed increased firing rate and norepinephrine release. Norepinephrine activated all three subtypes of alpha1 adrenergic receptor expressed by OPCs and evoked intracellular Ca2+ increase in OPCs. A chemogenetic activation of noradrenergic neurons, promoted differentiation of cortical OPCs into OL, and at the same time suppressed OPC proliferation rate. Hence, we uncovered that various cell types of oligodendrocyte lineage exhibits unique signatures of Ca2+ activity, which these cells might integrate for making their fate decisions, and norepinephrine signaling can be a potent regulator of OPC fate.

neuroscience↗

Norepinephrine enhances oligodendrocyte precursor cell calcium dynamics in the cerebral cortex during arousal

Oligodendrocytes are generated from a widely distributed population of progenitors that express neurotransmitter receptors, but the mechanisms that alter activity of these oligodendrocyte precursor cells (OPCs) in vivo have not been determined. We generated a novel line of transgenic mice to express membrane-anchored GCaMP6s in OPCs and used longitudinal two-photon microscopy to monitor their Ca2+ changes in the cerebral cortex of awake mice. OPCs exhibited high rates of spontaneous activity, consisting of focal, transient Ca2+ increases within their highly ramified processes. Unexpectedly, these events occurred independent of excitatory neuron activity, but were inhibited by anesthesia, sedative agents, and antagonists of noradrenergic signaling. These norepinephrine enhanced Ca2+ dynamics rapidly declined as with differentiation. Selective knockout of 1A adrenergic receptors in OPCs suppressed both spontaneous and locomotion-induced Ca2+ increases, indicating that OPCs are directly modulated by norepinephrine in vivo, providing a means to alter their dynamics and lineage progression during distinct brain states.

neuroscience↗

Detecting anomalous content in dairy with whole metagenome sequencing

The increasing knowledge of microbial ecology in food products relating to quality and safety and the established usefulness of machine learning algorithms for anomaly detection in multiple scenarios suggests that the application of microbiome data in food production systems for anomaly detection could be a valuable approach to be used in food systems. These methods could be used to identify ingredients that deviate from their typical microbial composition, which could indicate food fraud or safety issues. The objective of this study was to assess the feasibility of using shotgun sequencing data as input into anomaly detection algorithms using fluid milk as a model system. Contrastive PCA, cluster-based methods, and explainable AI were evaluated for the detection of two anomalous sample classes using longitudinal metagenomic profiling of fluid milk compared to baseline samples collected under comparable circumstances. Traditional methods (alpha and beta diversity, clustering-based contrastive PCA, MDS, and dendrograms) failed to differentiate anomalous sample classes; however, explainable AI was able to classify anomalous vs. baseline samples and indicate microbial drivers in association with antibiotic use. We validated the potential for explainable AI to classify different milk sources using larger publicly available fluid milk 16s rDNA sequencing datasets and demonstrated that explainable AI is able to differentiate between milk storage methods, processing stage, and season. Our results indicate the application of artificial intelligence continues to hold promise in the realm of microbiome data analysis and could present further opportunities for downstream analytic automation to aid in food safety and quality. IMPORTANCEWe evaluated the feasibility of using untargeted metagenomic se-quencing of raw milk for detecting anomalous food ingredient content with artificial intelligence methods in a study specifically designed to test this hypothesis. We also show through analysis of publicly available fluid milk microbial data that our artificial intelligence approach is able to successfully predict milk in different stages of process-ing. The approach could potentially be applied in the food industry for safety and quality control.

microbiology↗

Coordinated cadherin functions sculpt respiratory motor circuit connectivity

Breathing, and the motor circuits that control it, are essential for life. At the core of respiratory circuits are Dbx1-derived interneurons, which generate the rhythm and pattern of breathing, and phrenic motor neurons (MNs), which provide the final motor output that drives diaphragm muscle contractions during inspiration. Despite their critical function, the principles that dictate how respiratory circuits assemble are unknown. Here we show that coordinated activity of a type I cadherin (N-cadherin) and type II cadherins (Cadherin-6, -9, and -10) is required in both MNs and Dbx1-derived neurons to generate robust respiratory motor output. Both MN- and Dbx1-specific cadherin inactivation during a critical developmental window results in perinatal lethality due to respiratory failure and a striking reduction in phrenic MN bursting activity. This combinatorial cadherin code is required to establish phrenic MN cell body and dendritic topography; surprisingly, however, cell body position appears to be dispensable for the targeting of phrenic MNs by descending respiratory inputs. Our findings demonstrate that type I and type II cadherins function cooperatively throughout the respiratory circuit to generate a robust breathing output and reveal novel strategies that drive the assembly of motor circuits.

neuroscience↗

DeepPHiC: Predicting promoter-centered chromatin interactions using a novel deep learning approach

MotivationPromoter-centered chromatin interactions, which include promoter-enhancer and promoter-promoter interactions, are important to decipher gene regulation and disease mechanisms. The development of next generation sequencing technologies such as promoter capture Hi-C (pcHi-C) leads to the discovery of promoter-centered chromatin interactions. However, pcHi-C experiments are expensive and thus may be unavailable for tissues or cell types of interest. In addition, these experiments may be underpowered due to insufficient sequencing depth or various artifacts, which results in a limited finding of interactions. ResultsTo overcome these challenges, we develop a supervised multi-modal deep learning model, which utilizes a comprehensive set of features including genomic sequence, epigenetic signal and anchor distance to predict tissue/cell type-specific genome-wide promoter-enhancer and promoter-promoter interactions. We further extend the deep learning model in a multi-task learning and a transfer learning framework. We demonstrate that the proposed approach outperforms state-of-the-art deep learning methods and is robust to the inclusion of anchor distance as a feature. In addition, we find that the proposed approach can achieve comparable prediction performance using biologically relevant tissues/cell types compared to using all tissues/cell types especially for predicting promoter-enhancer interactions. Availabilityhttps://github.com/lichen-lab/DeepPHiC

bioinformatics↗

PIF4/HEMERA-mediated daytime thermosensory growth requires the Mediator subunit MED14

While moderately elevated ambient temperatures do not trigger stress responses in plants, they do significantly stimulate the growth of specific organs through a process known as thermomorphogenesis. The basic helix-loop-helix transcription factor PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) plays a central role in regulating thermomorphogenetic hypocotyl elongation in various plant species, including Arabidopsis thaliana. Although it is well known that PIF4 promotes plant thermosensory growth by activating genes involved in the biosynthesis and signaling of the phytohormone auxin, the detailed molecular mechanism of such transcriptional activation is not clear. Our previous studies demonstrated that HEMERA (HMR), a transcriptional co-activator of PIF4, promotes the thermo-induced expression of PIF4 target genes through its nine-amino-acid transactivation domain (9aaTAD). In this report, we investigate the role of the Mediator complex in the PIF4/HMR-mediated thermoresponsive gene expression. Through the characterization of various mutants of the Mediator complex, a tail subunit named MED14 is identified as an essential factor for thermomorphogenetic hypocotyl growth. MED14 is required for the thermal induction of PIF4 target genes but has a marginal effect on the levels of PIF4 and HMR. Further transcriptomic analyses confirm that the expression of numerous PIF4/HMR-dependent, auxin-related genes requires MED14 at warm temperatures. Moreover, PIF4 and HMR physically interact with MED14 and both are indispensable for the association of MED14 with the promoters of these thermoresponsive genes. Taken together, these results unveil an important thermomorphogenetic mechanism, in which PIF4 and HMR recruit the Mediator complex to activate auxin-related growth-promoting genes when plants sense moderate increases in ambient temperature. One-sentence summaryThe Mediator subunit MED14 promotes thermomorphogenesis by interacting with PHYTOCHROME-INTERACTING FACTOR 4 and HEMERA to induce the expression of growth-promoting genes at elevated temperatures.

plant biology↗

Predicting Epitope Candidates for SARS-CoV-2

Epitopes are short amino acid sequences that define the antigen signature to which an antibody binds. In light of the current pandemic, epitope analysis and prediction is paramount to improving serological testing and developing vaccines. In this paper, we leverage known epitope sequences from SARS-CoV, SARS-CoV-2 and other Coronaviridae and use those known epitopes to identify additional antigen regions in 62k SARS-CoV-2 genomes. Additionally, we present epitope distribution across SARS-CoV-2 genomes, locate the most commonly found epitopes, discuss where epitopes are located on proteins, and how epitopes can be grouped into classes. We also discuss the mutation density of different regions on proteins using a big data approach. We find that there are many conserved epitopes between SARS-CoV-2 and SARS-CoV, with more diverse sequences found in Nucleoprotein and Spike Glycoprotein.

bioinformatics↗

Structure of the rabies virus glycoprotein trimer bound to a pre-fusion specific neutralizing antibody

Rabies infection is nearly 100% lethal if untreated and kills over 50,000 people annually, many of them children. Existing rabies vaccines target the rabies virus glycoprotein (RABV-G) but generate short-lived immune responses, likely because the protein is heterogeneous under physiological conditions. Here, we report the 3.39[A] cryo-EM structure of trimeric, pre-fusion RABV-G complexed with RVA122, a potently neutralizing human antibody. RVA122 binds to a quaternary epitope at the top of RABV-G, bridging domains and stabilizing RABV-G protomers in a prefusion state. RABV-G trimerization involves side-to-side interactions between the central -helix and adjacent loops, rather than contacts between central helices, and interactions among the fusion loops at the glycoprotein base. These results provide a basis to develop improved rabies vaccines based on RABV-G stabilized in the prefusion conformation. One sentence summaryWe report the structure and trimeric interface of pre-fusion rabies virus glycoprotein bound to the neutralizing antibody RVA122.

microbiology↗

Spatial coding in the hippocampus of flying owls

The elucidation of spatial coding in the hippocampus requires exploring diverse animal species. While robust place-cells are found in the mammalian hippocampus, much less is known about spatial coding in the hippocampus of birds - and nothing is known about avian spatial representation during flight. Here we used a wireless-electrophysiology system to record single neurons in the hippocampus and related pallial structures from freely flying barn owls (Tyto alba) - a central-place nocturnal predator species with excellent navigational abilities. The owls 3D position was monitored while it flew back and forth between two perches. We found place cells - neurons that robustly represented the owls location during flight, and its flight-direction - as well as neurons that coded the owls perching position between flights. Spatial coding was invariant to changes in lighting conditions and to the position of a salient object in the room. Place cells were found in the anterior hippocampus and in the adjacent posterior hyperpallium apicale, and to a much lesser extent in the visual Wulst (visual-cortex homologue). The finding of place-cells in flying owls suggests commonalities in spatial coding across a variety of species - including rodents, bats and owls.

neuroscience↗

Brain networks in human conscious visual perception

Consciousness is not explained by a single mechanism, rather it involves multiple specialized neural systems overlapping in space and time. We hypothesize that synergistic, large-scale subcortical and cortical attention and signal processing networks encode conscious experiences. To identify brain activity in conscious perception without overt report, we classified visual stimuli as perceived or not using eye measurements. Report-independent event-related potentials and functional magnetic resonance imaging (fMRI) signals both occurred at early times after stimuli. Direct recordings revealed a novel thalamic awareness potential linked to conscious visual perception based on report. fMRI showed thalamic and cortical detection, arousal, attentional salience, task-positive, and default mode networks were involved independent of overt report. These findings identify a specific sequence of neural mechanisms in human conscious visual perception. One-Sentence SummaryHuman conscious visual perception engages large-scale subcortical and cortical networks even without overt report.

neuroscience↗

Spatiotemporal Modulations in Heterotypic Condensates of Prion and α-Synuclein Control Phase Transitions and Amyloid Conversion

Biomolecular condensates formed via liquid-liquid phase separation (LLPS) of proteins and nucleic acids are thought to govern critical cellular functions. These multicomponent assemblies provide dynamic hubs for competitive homotypic and heterotypic interactions. Here, we demonstrate that the complex coacervation between the prion protein (PrP) and -synuclein (-Syn) within a narrow stoichiometry regime results in the formation of highly dynamic liquid droplets. Domain-specific electrostatic interactions between the positively charged intrinsically disordered N-terminal segment of PrP and the negatively charged C-terminal domain of -Syn drive the formation of these highly tunable, reversible, thermo-responsive condensates. Picosecond time-resolved measurements revealed the existence of relatively ordered electrostatic nanoclusters that are stable on the nanosecond timescale and can undergo breaking-and-making on a much slower timescale giving rise to the liquid-like behavior on the second timescale and mesoscopic length-scale. The addition of RNA to these preformed coacervates yields multiphasic, anisotropic, vesicle-like, hollow condensates. LLPS promotes liquid-to-solid maturation of -Syn-PrP condensates resulting in the rapid conversion into heterotypic amyloids. Our results suggest that synergistic interactions between PrP and -Syn in liquid condensates can offer mechanistic underpinnings of their physiological role and overlapping neuropathological features.

biophysics↗

Mitochondrial dysfunction and oxidative stress contribute to cognitive and motor impairment in FOXP1 syndrome

There is increasing evidence that mitochondrial homeostasis - influenced by both genetic and environmental factors - is crucial in neurodevelopment. FOXP1 syndrome is a neurodevelopmental disorder that manifests motor dysfunction, intellectual disability, autism and language impairment. In this study, we used a Foxp1+/- mouse model to address whether cognitive and motor deficits in FOXP1 syndrome are associated with mitochondrial dysfunction and oxidative stress. Here we show that genes with a role in mitochondrial biogenesis and dynamics (e.g. Foxo1, Pgc-1, Tfam, Opa1, and Drp1) were dysregulated in the striatum of Foxp1+/- mice at different postnatal stages. Furthermore, in the striatum of Foxp1+/- animals, mitochondrial membrane potential was disrupted, and reactive oxygen species, lipid peroxidation and cytochrome c release were significantly elevated. These features can explain the reduced neurite branching, learning and memory, endurance, and motor coordination that we observed in these animals. Taken together, we provide strong evidence of mitochondrial dysfunction in Foxp1+/- mice, suggesting that insufficient energy supply and excessive oxidative stress underlies the cognitive and motor impairment in FOXP1 deficiency.

molecular biology↗

Utilizing proteomics and phosphoproteomics to predict ex vivo drug sensitivity across genetically diverse AML patients

Acute Myeloid Leukemia (AML) affects 20,000 patients in the US annually with a five-year survival rate of approximately 25%. One reason for the low survival rate is the high prevalence of clonal evolution that gives rise to heterogeneous sub-populations of leukemia. This genetic heterogeneity is difficult to treat using conventional therapies that are generally based on the detection of a single driving mutation. Thus, the use of molecular signatures, consisting of multiple functionally related transcripts or proteins, in making treatment decisions may overcome this hurdle and provide a more effective way to inform drug treatment protocols. Toward this end, the Beat AML research program prospectively collected genomic and transcriptomic data from over 1000 AML patients and carried out ex vivo drug sensitivity assays to identify signatures that could predict patient-specific drug responses. The Clinical Proteomic Tumor Analysis Consortium is in the process of extending this cohort to collect proteomic and phosphoproteomic measurements from a subset of these patient samples to evaluate the hypothesis that proteomic signatures can robustly predict drug response in AML patients. We sought to examine this hypothesis on a sub-cohort of 38 patient samples from Beat AML with proteomic and drug response data and evaluate our ability to identify proteomic signatures that predict drug response with high accuracy. For this initial analysis we built predictive models of patient drug responses across 26 drugs of interest using the proteomics and phosphproteomics data. We found that proteomics-derived signatures provide an accurate and robust signature of drug response in the AML ex vivo samples, as well as related cell lines, with better performance than those signatures derived from mutations or mRNA expression. Furthermore, we found that in specific drug-resistant cell lines, the proteins in our prognostic signatures represented dysregulated signaling pathways compared to parental cell lines, confirming the role of the proteins in the signatures in drug resistance. In conclusion, this pilot study demonstrates strong promise for proteomics-based patient stratification to predict drug sensitivity in AML.

bioinformatics↗

Semi-supervised identification of SARS-CoV-2 molecular targets

SARS-CoV-2 genomic sequencing efforts have scaled dramatically to address the current global pandemic and aid public health. In this work, we analyzed a corpus of 66,000 SARS-CoV-2 genome sequences. We developed a novel semi-supervised pipeline for automated gene, protein, and functional domain annotation of SARS-CoV-2 genomes that differentiates itself by not relying on use of a single reference genome and by overcoming atypical genome traits. Using this method, we identified the comprehensive set of known proteins with 98.5% set membership accuracy and 99.1% accuracy in length prediction compared to proteome references including Replicase polyprotein 1ab (with its transcriptional slippage site). Compared to other published tools such as Prokka (base) and VAPiD, we yielded an 6.4- and 1.8-fold increase in protein annotations. Our method generated 13,000,000 molecular target sequences-- some conserved across time and geography while others represent emerging variants. We observed 3,362 non-redundant sequences per protein on average within this corpus and describe key D614G and N501Y variants spatiotemporally. For spike glycoprotein domains, we achieved greater than 97.9% sequence identity to references and characterized Receptor Binding Domain variants. Here, we comprehensively present the molecular targets to refine biomedical interventions for SARS-CoV-2 with a scalable high-accuracy method to analyze newly sequenced infections.

bioinformatics↗

Convergent evolution of SARS-CoV-2 spike mutations, L452R, E484Q and P681R, in the second wave of COVID-19 in Maharashtra, India

As the global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic expands, genomic epidemiology and whole genome sequencing are being constantly used to investigate its transmissions and evolution. In the backdrop of the global emergence of "variants of concern" (VOCs) during December 2020 and an upsurge in a state in the western part of India since January 2021, whole genome sequencing and analysis of spike protein mutations using sequence and structural approaches was undertaken to identify possible new variants and gauge the fitness of current circulating strains. Phylogenetic analysis revealed that the predominant clade in circulation was a distinct newly identified lineage B.1.617 possessing common signature mutations D111D, G142D, L452R, E484Q, D614G and P681R, in the spike protein including within the receptor binding domain (RBD). Of these, the mutations at residue positions 452, 484 and 681 have been reported in other globally circulating lineages. The structural analysis of RBD mutations L452R and E484Q along with P681R in the furin cleavage site, revealed that these may possibly result in increased ACE2 binding and rate of S1-S2 cleavage resulting in better transmissibility. The same two RBD mutations indicated decreased binding to select monoclonal antibodies (mAbs) and may affect their neutralization potential. Experimental validation against a wider panel of mAbs, sera from vaccinees and those that recovered from natural infection needs to be studied. The emergence of such local variants through the accumulation of convergent mutations during the COVID-19 second wave needs to be further investigated for their public health impact in the rest of the country and its possibility of becoming a VOC.

molecular biology↗