Biology subjects

Mehta, A.

Publications and source records attributed to Mehta, A..

At least 37 records · Page 2Linked to original sources

bioRxiv2025

REBASTINIB, OLVEREMBATINIB, AND NAS-181 INHIBIT MYCOBACTERIUM ABSCESSUS BY DISRUPTING MYCOTHIOL HOMEOSTASIS

Nontuberculous mycobacteria (NTM), particularly Mycobacterium abscessus, pose a major clinical challenge due to intrinsic drug resistance and limited therapeutic options. In this study, we evaluated three repurposed kinase inhibitors, such as rebastinib, olverembatinib, and NAS-181for their antimycobacterial potential against M. abscessus. All three compounds displayed measurable in vitro activity, with MIC values of 22 M, 40 M, and 9 M, respectively. Whole-genome sequencing of resistant mutants revealed nonsynonymous mutations in key enzymes of the mycothiol biosynthesis pathway, including D87A and W227G substitutions in MshC (MAB_2116) and a Q51T substitution in MshA (MAB_4057c), implicating disruption of redox homeostasis as a likely mechanism of action. Consistent with this, biochemical analyses demonstrated a concentration-dependent decrease in intracellular mycothiol (MSH) and its precursor GlcN-Ins upon treatment with each compound. Cytotoxicity profiling indicated tolerable activity thresholds (rebastinib, 30 M; olverembatinib, 60 M; NAS-181, 14 M), enabling further macrophage infection assays. All three compounds significantly reduced intracellular M. abscessus burden in THP-1 macrophages without affecting host cell viability. In a mouse pulmonary infection model, treatment with rebastinib, olverembatinib, or NAS-181 (5 mg/kg) resulted in maintenance of body weight, decreased lung CFU counts, and reduced spleen enlargement compared to vehicle controls, with efficacy comparable to amikacin. Collectively, these findings identify rebastinib, olverembatinib, and NAS-181 as promising repurposed drug candidates that target mycothiol biosynthesis, providing a foundation for the development of novel therapeutic strategies against drug-resistant M. abscessus.

microbiology↗

bioRxiv2025

Functional genomics and tumor microenvironment analysis reveal prognostic biological subtypes in Mantle cell lymphoma

Mantle cell lymphoma (MCL) is a genetically and clinically heterogeneous B-cell malignancy. We studied two MCL cohorts with differing treatment patterns: one enriched for immunochemotherapy, the other for chemotherapy alone. TP53 alterations were consistently associated with poor prognosis, whereas ATM mutations correlated with improved outcomes following rituximab-based chemotherapy. Based on recurrent genetic events, six clusters were identified and refined into three prognostic groups: high-risk (TP53 mutations and deletions at 17p13.3, 13q14.2, and 19p13.3), intermediate-risk (ATM and epigenetic regulator mutations, or gains at 8q/17q/15q), and low-risk (lacking TP53 alterations, rare ATM mutations without 11q deletions, gains at 3q, deletions at 6q). Transcriptomic analysis revealed enrichment of proliferation, metabolism-promoting gene signatures in high-risk; angiogenesis and NOTCH signaling in intermediate-risk; and proinflammatory-related (i.e., IFN, TNF) in low-risk MCLs. Multi-proteomic spatial profiling using imaging mass cytometry (IMC) demonstrated enrichment of CD8 T cells with high expression of exhaustion markers and dominant population of myeloid cells skewed toward an M2-like phenotype. Compared to ATM-perturbed tumors, TP53-perturbed tumors exhibited enriched SOX11 tumor cells and enhanced tumor-immune cell interactions. Functional analysis revealed that p53 represses BCR signaling through PTPN6 activation. Collectively, these findings highlight distinct molecular and immune landscapes and reveal therapeutic vulnerabilities in high-risk TP53-altered MCL.

cancer biology↗

bioRxiv2025

Evolution of antibody cross-reactivity to influenza H5N1 neuraminidase from an N2-specific germline

The ongoing spread of highly pathogenic avian influenza H5N1 clade 2.3.4.4b virus in animals and its occasional spillover to humans have raised concerns about a potential H5N1 pandemic. Although recent studies have shown that pre-existing human antibodies can recognize H5N1 neuraminidase, the molecular basis of how this cross-reactivity develops remains poorly understood. In this study, we used a phage display antibody library derived from 245 healthy donors to isolate an antibody, HB420, that cross-reacts with neuraminidases of human H3N2 and avian H5N1 clade 2.3.4.4b viruses and confers protection in vivo. Cryo-EM analysis reveals that HB420 targets the neuraminidase active site by mimicking sialic acid binding through a single Asp residue. Furthermore, the inferred germline of HB420 is N2-specific but acquires cross-reactivity to H5N1 neuraminidase through somatic hypermutation. Overall, our findings provide insights into how neuraminidase antibody evolves breadth, which has important implications for the development of broadly protective influenza vaccines.

immunology↗

bioRxiv2025

Bringing the Genetically Minimal Cell to Life on a Computer in 4D

We present a whole-cell spatial and kinetic model for the 100 minute cell cycle of the genetically minimal bacterium, JCVI-syn3A. This is the first simulation of a complete cell cycle in 4D including all genetic information processes, metabolic networks, growth, and cell division. Integrating hybrid computational methods, dynamics of the morphological transformations were achieved. Growth is driven by synthesis of lipids and membrane proteins and constrained by new fluorescence imaging data. Chromosome replication and segregation is controlled by essential SMC and topoisomerase proteins in Brownian dynamics simulations with replication rates responding to dNTP pools from metabolism. The model captures the origin to terminus ratio measured in our DNA sequencing and recovers other experimental measurements like doubling time, mRNA half-lives, protein distributions, and ribosome counts. Because of stochasticity, each replicate cell is unique. Not only do we predict average behavior for partitioning to daughter cells, we predict the heterogeneity among them.

biophysics↗

bioRxiv2025

Extrachromosomal DNA Gives Cancer a New Evolutionary Pathway

During tumor progression, it has been assumed that individual cells that have acquired advantageous mutations overtake the population. Cancers driven by extrachromosomal DNA (ecDNA) do not follow this paradigm. Instead, these tumors have a spectrum of oncogene copy numbers across cells, and graded ecDNA variation may function as a form of bet-hedging that equips tumors with a broad range of phenotypes. Using imaging, single-cell multiomics, and multiplexed proteomics, we systematically characterized ecDNA levels across thousands of single cells. Higher ecDNA dosage produces proportional changes in transcript abundance, chromatin accessibility, protein levels, cell-cycle progression, and proliferation. Genes amplified on ecDNA exhibit distinct transcriptional scaling regimes that shift when the same genes are reintegrated into chromosomal homogeneous staining regions. When we experimentally disrupted the continuum of ecDNA dosage by sorting cells into low- and high-copy number states, the population rapidly recovered its original, continuous distribution. Our time-course data, live-cell imaging, and stochastic models collectively show that restoring this spectrum is an active, deterministic process rather than the passive outcome of random segregation. Together, these findings position ecDNA-mediated expression as a distinct evolutionary mechanism that endows tumors with rapid, population-level adaptability. These findings offer insight into why ecDNA-driven cancers are among the most aggressive and treatment-resistant.

genomics↗

bioRxiv2025

Transcriptomic plasticity is a hallmark of metastatic pancreatic cancer

Metastasis is the leading cause of cancer deaths; nonetheless, how tumor cells adapt to vastly different organ contexts is largely unknown. To investigate this question, we generated a transcriptomic atlas of primary tumor and diverse metastatic samples from a patient with pancreatic ductal adenocarcinoma who underwent rapid autopsy. Unsupervised archetype analysis identified both shared and site-specific gene programs, including lipid metabolism and gastrointestinal programs prevalent in peritoneum and stomach wall lesions, respectively. We developed a probabilistic approach for inferring clonal phylogeny from single-cell and matched whole-exome data. Distantly related genetic clones in the peritoneum express the lipid metabolism program, likely due to signaling by the adipocyte-rich peritoneum environment, and cells in most clones express multiple programs, suggesting that transcriptomic plasticity is a prevalent feature of metastatic cells. These deeply annotated analyses using a patient-centric platform provide a model for investigating metastatic mechanisms and plasticity in advanced cancer.

bioinformatics↗

bioRxiv2024

Leveraging AI to Automate Detection and Quantification of Extrachromosomal DNA (ecDNA) to Decode Drug Responses

Traditional drug discovery efforts have largely focused on targeting rapid, reversible protein-mediated adaptations to undermine cancer cells resistance to therapy. However, cancer cells also exploit DNA-based strategies, typically viewed as slow, irreversible, and unpredictable changes like point mutations or the selection of drug-resistant clones. Contrary to this perception, extrachromosomal DNA (ecDNA) represents a form of DNA alteration that is rapid, reversible, and predictable, playing a crucial role in cancers adaptive response. In this study, we present a novel post-processing pipeline for the automated detection and quantification of ecDNA in Fluorescence in situ Hybridization (FISH) images using the Microscopy Image Analyzer (MIA) tool. Our approach is particularly designed to monitor ecDNA dynamics during drug treatment, providing a quantitative framework to understand how ecDNA enables cancer cells to swiftly and reversibly adapt to therapeutic pressure. This pipeline not only offers a valuable resource for researchers aiming to automate ecDNA detection in FISH images but also sheds light on the adaptive mechanisms of ecDNA in response to epigenetic remodeling agents like JQ1.

cancer biology↗

bioRxiv2024

Joint population coding and temporal coherence link an attended talker's voice and location features in naturalistic multi-talker scenes.

Listeners effortlessly extract multidimensional auditory objects, such as a localized talker, from complex acoustic scenes. However, the neural mechanisms that enable simultaneous encoding and linking of distinct sound features--such as a talkers voice and location--are not fully understood. Using invasive intracranial recordings in neurosurgical patients, we investigated how the human auditory cortex processes and integrates these features during naturalistic multi-talker scenes. We found that cortical sites exhibit a gradient of feature sensitivity, ranging from single-feature sensitive sites (responsive primarily to voice or location) to dual-feature sensitive sites (responsive to both features). At the population level, neural response patterns from both single- and dual-feature sensitive sites jointly encoded the attended talkers voice and location. Notably, single-feature sensitive sites encoded their primary feature with greater precision but also represented coarse information about the secondary feature. Sites selectively tracking a single, attended speech stream concurrently encoded both voice and location features, demonstrating a link between selective attention and feature integration. Additionally, attention selectively enhanced temporal coherence between voice- and location-sensitive sites, suggesting that temporal synchronization serves as a mechanism for linking these features. Our findings highlight two complementary neural mechanisms--joint population coding and temporal coherence-- that enable the integration of voice and location features in the auditory cortex. These results provide new insights into the distributed, multidimensional nature of auditory object formation during active listening in complex environments. SIGNIFICANCE STATEMENTIn everyday life, listeners effortlessly extract individual sound sources from complex acoustic scenes which contain multiple sound sources. Yet, how the brain links the different features of a particular sound source to each other - such as a talkers voice characteristics and location - is poorly understood. Here, we show that two neural mechanisms contribute to encoding and integrating voice and location features in multi-talker sound scenes: (1) some neuronal sites are sensitive to both voice and location and their activity patterns encode these features jointly; (2) the responses of neuronal sites that process only one sound feature - that is, location or voice - align temporally to form a stream that is segregated from the other talker. HIGHLIGHTSO_LIAuditory cortex exhibits a gradient of feature sensitivity, with some sites encoding only voice or location features, while others encode both simultaneously (dual-feature sensitive sites). C_LIO_LIDual-feature sensitive sites integrate voice and location features of an attended talker with equal accuracy, providing a unified representation in multi-talker scenes. C_LIO_LISingle-feature sensitive sites primarily encode their preferred feature with high precision but also represent coarse information about other features, contributing to population-level integration. C_LIO_LITemporal coherence selectively enhances synchronization between voice- and location-sensitive sites, providing another mechanism for integrating an auditory objects features. C_LIO_LIMulti-dimensional auditory object formation relies on complementary neural mechanisms: joint population coding and temporal coherence. C_LI

neuroscience↗

bioRxiv2024

Hippocampal sharp wave ripples and coincident cortical ripples orchestrate human semantic networks

Episodic memory function is predicated upon the precise coordination between the hippocampus and widespread cortical regions. However, our understanding of the neural mechanisms involved in this process is incomplete. In this study, human subjects undergoing intracranial electroencephalography (iEEG) monitoring performed a list learning task. We show sharp-wave ripple (SWR)-locked reactivation of specific semantic processing regions during free recall. This cortical activation consists of both broadband high frequency (non-oscillatory) and cortical ripple (oscillatory) activity. SWRs and cortical ripples in the anterior temporal lobe, a major semantic hub, co-occur and increase in rate prior to recall. Coincident hippocampal-ATL ripples are associated with a greater increase in cortical reactivation, show specificity in location based on recall content, and are preceded by cortical theta oscillations. These findings may represent a reactivation of hippocampus and cortical semantic regions orchestrated by an interplay between hippocampal SWRs, cortical ripples, and theta oscillations.

neuroscience↗

bioRxiv2024

Disrupting CD38-driven T cell dysfunction restores sensitivity to cancer immunotherapy

A central problem in cancer immunotherapy with immune checkpoint blockade (ICB) is the development of resistance, which affects 50% of patients with metastatic melanoma1,2. T cell exhaustion, resulting from chronic antigen exposure in the tumour microenvironment, is a major driver of ICB resistance3. Here, we show that CD38, an ecto-enzyme involved in nicotinamide adenine dinucleotide (NAD+) catabolism, is highly expressed in exhausted CD8+ T cells in melanoma and is associated with ICB resistance. Tumour-derived CD38hiCD8+ T cells are dysfunctional, characterised by impaired proliferative capacity, effector function, and dysregulated mitochondrial bioenergetics. Genetic and pharmacological blockade of CD38 in murine and patient-derived organotypic tumour models (MDOTS/PDOTS) enhanced tumour immunity and overcame ICB resistance. Mechanistically, disrupting CD38 activity in T cells restored cellular NAD+ pools, improved mitochondrial function, increased proliferation, augmented effector function, and restored ICB sensitivity. Taken together, these data demonstrate a role for the CD38-NAD+ axis in promoting T cell exhaustion and ICB resistance, and establish the efficacy of CD38 directed therapeutic strategies to overcome ICB resistance using clinically relevant, patient-derived 3D tumour models.

cancer biology↗

bioRxiv2023

CytoCellDB: A Resource Database For Classification and Analysis of Extrachromosomal DNA in Cancer

Extrachromosomal DNA (ecDNA), or double minute chromosomes, are established cytogenetic markers for malignancy and genome instability. More recently, the cancer community has gained a heightened awareness of the roles of ecDNA in cancer proliferation, drug resistance and epigenetic remodeling. A current hindrance to understanding the biological roles of ecDNA is the lack of available cell line model systems with experimental cytogenetic data that confirm ecDNA status. Although several recent landmark studies have identified common cell lines and tumor models with ecDNA, the current sample size limits our ability to detect ecDNA-driven molecular differences due to limitations in power. Increasing the number of model systems known to express ecDNA would provide new avenues for understanding the fundamental underpinnings of ecDNA biology and would unlock a wealth of potential targeting strategies for ecDNA-driven cancers. To bridge this gap, we created CytoCellDB, a resource that provides karyotype annotations and leverages publicly available global cell line data from the Cancer Dependency Map (DepMap) and the Cancer Cell Line Encyclopedia (CCLE). Here, we identify 139 cell lines that express ecDNA, which is a 200% increase from the current sample size. We expanded the total number of cancer cell lines with ecDNA annotations to 577, which is a 400% increase or 31% of cell lines in CCLE/ DepMap. We demonstrate that a strength of CytoCellDB is the ability to interrogate ecDNA, and a compendium of other chromosomal aberrations, in the context of cancer-specific vulnerabilities, drug sensitivities, and molecular data (genomics, transcriptomics, methylation, proteomics). We anticipate that CytoCellDB will advance cytogenomics research and population-scale discoveries related to ecDNA as well as provide insights into strategies and best practices for determining novel therapeutics that overcome ecDNA-driven drug resistance.

genomics↗

bioRxiv2023

SpaceANOVA: Spatial co-occurrence analysis of cell types in multiplex imaging data using point process and functional ANOVA

MotivationMultiplex imaging platforms have enabled the identification of the spatial organization of different types of cells in complex tissue or tumor microenvironment (TME). Exploring the potential variations in the spatial co-occurrence or co-localization of different cell types across distinct tissue or disease classes can provide significant pathological insights, paving the way for intervention strategies. However, the existing methods in this context either rely on stringent statistical assumptions or suffer from a lack of generalizability. ResultsWe present a highly powerful method to study differential spatial co-occurrence of cell types across multiple tissue or disease groups, based on the theories of the Poisson point process (PPP) and functional analysis of variance (FANOVA). Notably, the method accommodates multiple images per subject and addresses the problem of missing tissue regions, commonly encountered in such a context due to the complex nature of the data-collection procedure. We demonstrate the superior statistical power and robustness of the method in comparison to existing approaches through realistic simulation studies. Furthermore, we apply the method to three real datasets on different diseases collected using different imaging platforms. In particular, one of these datasets reveals novel insights into the spatial characteristics of various types of precursor lesions associated with colorectal cancer. AvailabilityThe associated R package can be found here, https://github.com/sealx017/SpaceANOVA. Contactsealso@musc.edu Supplementary informationThe supplementary material is attached.

bioinformatics↗

bioRxiv2023

A rapid and bidirectional reporter of neural activity reveals neural correlates of social behaviors in Drosophila

Neural activity is modulated over different timescales encompassing sub-seconds to days reflecting changes in external environment, internal state, and behavior. Using Drosophila as a model, we have developed a rapid and bidirectional reporter that provides a robust cellular readout of recent neural activity. This reporter utilizes nuclear vs cytoplasmic distribution of CREB-regulated transcriptional coactivator, CRTC. Subcellular distribution of GFP-tagged CRTC (CRTC::GFP) bidirectionally changes on the order of minutes and reflects both increases and decreases in neural activity. We establish an automated machine-learning-based routine for efficient quantification of reporter signal. Using this reporter, we demonstrate acute mating- evoked activation of peptidergic neurons. We further investigate the functional role of the master courtship regulator gene, fruitless, and show that fruitless is necessary to ensure activation of male arousal neurons by female cues. Together, our results establish CRTC::GFP as a bidirectional reporter of recent neural activity suitable for examining neural correlates in behavioral contexts.

neuroscience↗

bioRxiv2023

Spatial analysis of human lung cancer reveals organized immune hubs enriched for stem-like CD8 T cells and associated with immunotherapy response

The organization of immune cells in human tumors is not well understood. Immunogenic tumors harbor spatially-localized multicellular immunity hubs defined by expression of the T cell-attracting chemokines CXCL10/CXCL11 and abundant T cells. Here, we examined immunity hubs in human pre-immunotherapy lung cancer specimens, and found that they were associated with beneficial responses to PD-1-blockade. Immunity hubs were enriched for many interferon-stimulated genes, T cells in multiple differentiation states, and CXCL9/10/11+ macrophages that preferentially interact with CD8 T cells. Critically, we discovered the stem-immunity hub, a subtype of immunity hub strongly associated with favorable PD-1-blockade outcomes, distinct from mature tertiary lymphoid structures, and enriched for stem-like TCF7+PD-1+ CD8 T cells and activated CCR7+LAMP3+ dendritic cells, as well as chemokines that organize these cells. These results elucidate the spatial organization of the human intratumoral immune response and its relevance to patient immunotherapy outcomes.

immunology↗

bioRxiv2023

Magnetically Controlled Cyclic Microscale Deformation of in vitro Cancer Invasion Models

Mechanical cues play an important role in the metastatic cascade of cancer. Three-dimensional (3D) tissue matrices with tunable stiffness have been extensively used as model systems of the tumor microenvironment for physiologically relevant studies. Tumor-associated cells actively deform these matrices, providing mechanical cues to other cancer cells residing in the tissue. Mimicking such dynamic deformation in the surrounding tumor matrix may help clarify the effect of local strain on cancer cell invasion. Remotely controlled microscale magnetic actuation of such 3D in vitro systems is a promising approach, offering a non-invasive means for in situ interrogation. Here, we investigate the influence of cyclic deformation on tumor spheroids embedded in matrices, continuously exerted for days by cell-sized anisotropic magnetic probes, referred to as {micro}Rods. Particle velocimetry analysis revealed the spatial extent of matrix deformation produced in response to a magnetic field, which was found to be on the order of 200 {micro}m, resembling strain fields reported to originate from contracting cells. Intracellular calcium influx was observed in response to cyclic actuation, as well as an influence on cancer cell invasion from 3D spheroids, as compared to unactuated controls. Localized actuation at one side of a tumor spheroid tended to result in anisotropic invasion toward the {micro}Rods causing the deformation. In summary, our approach offers a strategy to test and control the influence of non-invasive micromechanical cues on cancer cell invasion and metastasis.

bioengineering↗

bioRxiv2023

The neural activity of auditory conscious perception

Although recent work has made significant headway in understanding the temporal and spatial dynamics of the neural mechanisms of conscious perception, much of that work has focused on visual paradigms. To determine whether there are shared mechanisms for perceptual consciousness across sensory modalities, here we developed a task to test within the auditory domain. Participants (n=31) completed an auditory perceptual threshold task while undergoing intracranial electroencephalography (icEEG) for intractable epilepsy. Intracranial recordings from over 2,800 grey matter electrodes representing widespread cortical coverage were analyzed for power in the high gamma range (40-115 Hz)--a frequency range that reflects local neural activity. For trials that were perceived, we find activity in early auditory regions which is accompanied by activity in the right caudal middle frontal gyrus, and shortly thereafter by activity in non-auditory thalamus. This is followed by a wave of activity that sweeps through the higher auditory association regions and into parietal and frontal cortices, similar to the wave observed in our visual conscious perception paradigm. However, for not perceived trials, we find that significant activity is restricted to early auditory regions (and areas immediately adjacent to the Sylvian fissure). These findings show that the broad anatomical regions of cortical and subcortical networks involved in auditory perception are similar to the networks observed with vision, suggesting shared general mechanisms for conscious perception.

neuroscience↗

bioRxiv2022

Integrative single cell and spatial transcriptomics of colorectal cancer reveals multicellular functional units that support tumor progression

While advances in single cell genomics have helped to chart the cellular components of tumor ecosystems, it has been more challenging to characterize their specific spatial organization and functional interactions. Here, we combine single cell RNA-seq, spatial transcriptomics by Slide-seq, and in situ multiplex RNA analysis, to create a detailed spatial map of healthy and dysplastic colon cellular ecosystems and their association with disease progression. We profiled inducible genetic CRC mouse models that recapitulate key features of human CRC, assigned cell types and epithelial expression programs to spatial tissue locations in tumors, and computationally used them to identify the regional features spanning different cells in the same spatial niche. We find that tumors were organized in cellular neighborhoods, each with a distinct composition of cell subtypes, expression programs, and local cellular interactions. Comparing to scRNA-seq and Slide-seq data from human CRC, we find that both cell composition and layout features were conserved between the species, with mouse neighborhoods correlating with malignancy and clinical outcome in human patient tumors, highlighting the relevance of our findings to human disease. Our work offers a comprehensive framework that is applicable across various tissues, tumors, and disease conditions, with tools for the extrapolation of findings from experimental mouse models to human diseases.

cancer biology↗

bioRxiv2022

Extracellular vesicles induce aggressive lung cancervia non-canonical integrin-EGFR-KRAS signaling

Small cell lung cancer (SCLC) is an extremely aggressive lung cancer type with a patient median survival of 6-12 months. Epidermal growth factor (EGF) signaling plays an important role in triggering SCLC. In addition, growth factor-dependent signals and alpha-, beta-integrin (ITGA, ITGB) heterodimer receptors functionally cooperate and integrate their signaling pathways. However, the precise role of integrins in EGF receptor (EGFR) activation in SCLC has remained elusive. We analyzed RNA-sequencing data, human precision-cut lung slices (hPCLS), retrospectively collected human lung tissue samples and cell lines to demonstrate that non-canonical ITGB2 signaling activates EGFR and RAS/MAPK/ERK signaling in SCLC. Further, we identified a novel SCLC gene expression signature consisting of 93 transcripts that were induced by ITGB2, which might be used for stratification of SCLC patients, prognosis prediction of LC patients and development of patient-tailored therapies. We also found by proteomic analysis a cell-cell communication mechanism based on extracellular vesicles (EVs) containing ITGB2, which were secreted by SCLC cells and induced in control human lung tissue RAS/MAPK/ERK signaling and SCLC markers. We uncovered a mechanism of ITGB2-mediated EGFR activation in SCLC that explains EGFR-inhibitor resistance independently of EGFR mutations, suggesting the development of therapies targeting ITGB2 for patients with this extremely aggressive lung cancer type.

cancer biology↗