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Sharma, A.

Publications and source records attributed to Sharma, A..

At least 163 records · Page 9Linked to original sources

Decoding stress specific transcriptional regulation by causality aware Graph-Transformer deep learning

Cells respond to environmental stimuli through transcriptional reprogramming orchestrated by transcription factors (TFs), which interpret cis-regulatory DNA sequences to determine the timing and location of gene expression. The diversification of TFs and their interactions with cis-regulatory elements (CREs) underpins plant adaptation to stress through the formation of gene regulatory networks (GRNs). However, deciphering condition-specific GRNs and identifying transcription factor binding motifs (TFBMs) for spatio-temporal gene expression remain major challenges in plant biology. To decipher the conditional networks governing TF-Target gene interactions, we developed CTF-BIND, a novel computational framework designed to reason about the spatio-temporal dynamics of TF activity. Leveraging over [~]23TB of multi-omics data (ChIP-seq, RNA-seq, and protein-protein interaction data), we constructed Bayesian causal networks capable of explaining TF activity across diverse conditions. These networks, validated against extensive experimental data, were then integrated into a Graph Transformer deep learning system. This system uses expression information of network components to quantitatively determine TF activity levels. Models were developed for 110 abiotic stress-related TFs, enabling accurate condition-specific detection of TF binding directly from RNA-seq data, eliminating the need for separate ChIP-seq experiments. CTF-BIND achieved a high average accuracy of [~]93% when tested against experimentally established data from various conditions. It is implemented as an interactive, open-access web server, it not only provides TF binding profiles but also facilitates downstream functional analysis. Furthermore, we developed CTF-BIND-DB, (https://hichicob.ihbt.res.in/ctfbind/) a database capturing dynamic shifts in regulatory pathways, providing information on TGs, network ontology, and binding motifs. CTF-BIND and CTF-BIND-DB represent a transformative approach for understanding and determining TF activity in plant stress responses, offering a powerful tool for crop improvement and bypassing the limitations of traditional methods and extensive experimental validation.

bioinformatics↗

Cell-Surface LAMP1 is a Senescence Marker in Aging and Idiopathic Pulmonary Fibrosis

The accumulation of senescent cells (SEN) with aging produces a chronic inflammatory state that accelerates age-related diseases. Eliminating SEN has been shown to delay, prevent, and in some cases reverse aging in animal disease models and extend lifespan. There is thus an unmet clinical need to identify and target SEN while sparing healthy cells. Here, we show that Lysosomal-Associated Membrane Protein 1 (LAMP1) is a membrane-specific biomarker of cellular senescence. We have validated selective LAMP1 upregulation in SEN in human and mouse cells. Lamp1+ cells express high levels of prototypical senescence markers p16, p21, Glb1, and have low Lmnb1 expression as compared to Lamp1- cells. The percentage of Lamp1+ cells is increased in mice with fibrotic lungs after bleomycin instillation. Finally, we use a dual antibody-drug conjugate (ADC) strategy to eliminate LAMP1+ senescent cells.

molecular biology↗

SPINK1-COL18A1 Crosstalk Shapes Epigenome and Drives Cancer Stemness in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a devastating cancer with an increasing incidence and extremely dismal prognosis. Discovery and mechanistic understanding of the genetic and epigenetic drivers of PDAC is therefore of critical importance. Here, we uncover serine protease inhibitor Kazal type 1 (SPINK1) as a putative determinant of clinical progression and demonstrate that it can have a non-canonical function as a regulator of epigenomic states of PDAC cells and associated extensive changes in gene expression. We show that SPINK1 expression, which varies in PDAC, is associated with key aggressive phenotypic cancer states and is correlated with the expression of stemness markers both in vitro and in patient samples. Mechanistically, our results strongly suggest that SPINK1 acts through a new signaling axis, by interacting with COL18A1 in the Golgi apparatus, promoting endostatin release and eventually inducing extensive histone H3 modifications. These results reveal a new function of SPINK1 in PDAC and suggest a potential therapeutic route to combat PDAC aggressiveness by targeting the SPINK1-COL18A1-endostatin signaling.

cancer biology↗

Engineered basement membrane mimetic hydrogels to study mammary epithelial morphogenesis and invasion

Reconstituted basement membrane (rBM) products like Matrigel are widely used in 3D culture models of epithelial tissues and cancer. However, their utility is hindered by key limitations, including batch variability, xenogenic contaminants, and a lack of tunability. To address these challenges, we engineered a 3D basement membrane (eBM) matrix by conjugating defined extracellular matrix (ECM) adhesion peptides (IKVAV, YIGSR, RGD) to an alginate hydrogel network with precisely tunable stiffness and viscoelasticity. We optimized the mechanical and biochemical properties of the engineered basement membranes (eBMs) to support mammary acinar morphogenesis in MCF10A cells, similar to rBM. We found that IKVAV-modified, fast-relaxing ({tau}1/2 = 30-150 s), and soft (E = 200 Pa) eBMs best promoted polarized acinar structures. Clusters became invasive and lost polarity only when the IKVAV-modified eBM exhibited both similar stiffness to a malignant breast tumor (E = 4000 Pa) and slow stress relaxation ({tau}1/2 = 600-1100 s). Notably, tumor-like stiffness alone was not sufficient to drive invasion in fast stress relaxing matrices modified with IKVAV. In contrast, RGD-modified matrices promoted a malignant phenotype regardless of mechanical properties. We also utilized this system to interrogate the mechanism driving acinar and tumorigenic phenotypes in response to microenvironmental parameters. A balance in activity between {beta}1- and {beta}4-integrins was observed in the context of IKVAV-modified eBMs, prompting further investigation into the downstream mechanisms. We found differences in hemidesmosome formation and production of endogenous laminin in response to peptide type, stress relaxation, and stiffness. We also saw that inhibiting either focal adhesion kinase or hemidesmosome signaling in IKVAV eBMs prevented acinus formation. This eBM matrix is a powerful, reductionist, xenogenic-free system, offering a robust platform for both fundamental research and translational applications in tissue engineering and disease modeling.

bioengineering↗

Knowledge Discovery in Datasets of Proteomics by Systems Modeling in Translational Research on Pancreatic Cancer

Knowledge discovery in databases (KDD) can contribute to translational research, also known as translational medicine, by bridging the gap between in vitro and in vivo studies and clinical applications. Here, we propose a systems modeling workflow for KDD. This framework includes data collection of composition model (various research models) and processing model (proteomics) and analytical model (bioinformatics, artificial intelligence/machine leaning and pattern evaluation), knowledge presentation, and feedback loops for hypothesis generation and validation. We applied this workflow to study pancreatic ductal adenocarcinoma (PDAC). Through this approach, we identified the common proteins between human PDAC and various research models in vitro (cells, spheroids and organoids) and in vivo (mouse mice). Accordingly, we hypothesized potential translational targets on hub proteins and the related signaling pathways, PDAC specific proteins and signature pathways, and high topological proteins. Thus, we suggest that this systems modeling workflow can be a valuable method for KDD, facilitating knowledge discovery in translational targets in general and in particular to PADA in this case.

systems biology↗

Reconstructed Cell-Type Specific Rhythms in Human Brain link Alzheimer's Pathology, Circadian Stress, and Ribosomal Disruption

Alzheimers disease (AD) disrupts behavioral circadian rhythms, but its effects on molecular rhythms in the human brain are poorly understood. Using single-nucleus RNA sequencing from post-mortem cortical samples, we informatically estimated the relative circadian phases of 409 persons with and without AD dementia. We then reconstructed circadian expression profiles across cell types. While core clock rhythms were preserved in AD, many cell-type specific circadian outputs were disrupted. Rhythms in ribosomal biogenesis and oxidative phosphorylation were dampened across cell types. Similar losses in ribosomal gene expression rhythms were observed in APP/PS1 mice, which showed further reductions in ribosomal protein expression and polysome-mediated translation after circadian desynchrony. Exploratory computational modeling reveals that altered translation may contribute to the increased circadian variability seen in AD patients. These findings reveal altered cell-type specific circadian output rhythms in the brains of AD affected patients, and highlight disrupted ribosomal rhythms as a feature of AD.

bioinformatics↗

Analysis of the current state of frailty indexes and their implementation for aging intervention studies

Animal lifespan studies are foundational to developing interventions against the biological aging process. In recent years, there has been rising interest in characterizing the effects of longevity therapeutics on health span. Frailty indexes, originally developed to assess clinical frailty in aging humans, have shown promise as measurements of biological age and have been adopted for use in rodent aging biology. This perspective looks at the current state of rodent frailty indexes and how they are implemented. The differences in frailty parameters used to calculate these indexes have led to inconsistencies between studies defining frailty. In this perspective, we have highlighted those differences and made recommendations for implementing protocols for frailty index measurement.

animal behavior and cognition↗

Peroxisomal Dysfunction Drives Loss of Dynamic Nutrient Responses to Initiate Metabolic Inflexibility During Aging

Aging results in a loss of metabolic flexibility during fasting, characterized by the inability to acutely switch between metabolic substrates and reduced lipid mobilization. However, the drivers of these effects intracellularly remain unclear. Here, in Caenorhabditis elegans, we show that loss of coordinated inter-organelle dynamics causally initiates metabolic inflexibility with age. In young animals, peroxisomes emerge as the priming orchestrators of the fasting response, simultaneously governing lipid droplets (LDs) utilization and mitochondrial bioenergetics. With age, peroxisomal priming is lost, leading to mitochondrial fragmentation and impaired dynamic nutrient responses during fasting. Notably, dietary restriction (DR) exerts a rejuvenating effect on peroxisomal function, thereby preserving mitochondrial integrity and promoting longevity. Our study uncovers the expansive network of organelles enabling lipid mobilization during youth, providing critical context to the poorly understood role of peroxisomes in actively maintaining organelle homeodynamics and metabolic flexibility throughout the aging process.

cell biology↗

Senolytics Restore Hematopoietic Stem Cells Function in Sickle Cell Disease

Sickle Cell Disease (SCD) is a blood disorder affecting millions worldwide. Emerging evidence reveals that SCD pathophysiology increases risk of myeloid malignancies and hematopoietic stem cell (HSC) dysfunction, possibly due to pathological stress on bone marrow. To investigate this further, we interrogated mice and individuals with SCD and observed extended cell cycle times, oxidative stress, DNA damage, senescence, and dysregulation of molecular programs associated with these processes in bone marrow hematopoietic stem and progenitor cells (HSPCs). Human SCD HSPCs displayed poor hematopoietic potential ex vivo. SCD mice displayed a dramatic loss of transplantable bone marrow HSPCs, which was reversed upon treatment of SCD mice with the senolytic agent, ABT-263 (navitoclax). Thus, senolytics restore bone marrow function during SCD in mice and represent a novel strategy to improve bone marrow health in individuals with SCD and improve the safety of potentially curative gene therapies that utilize autologous HSPCs from individuals with SCD.

cell biology↗

Ribbit: Accurate identification and annotation of complex tandem repeat sequences in genomes

DNA tandem repeats (TRs) are crucial for genomic functions like protein binding, chromatin modulation, splicing, and gene regulation. Abnormal length variations in TRs, especially expansions, are associated with over 60 neurodegenerative diseases. The function and stability of a TR locus is dependent on its sequencing composition and purity. Recent studies report the disease-causing propensity of non-canonical motif expansions in TR loci, and highlight the intricate polymorphism dynamics in complex loci encompassing adjacent, overlapping, and nested TRs. These reports emphasize the need for precise definition and motif decomposition of TR loci. To address this, we present Ribbit, a tool that accurately and efficiently identifies and annotates TR loci in a genome. Ribbit uses 2-bit representation of DNA sequences for rapid identification of TRs of 2-100 bp motif size and resolves complex TR structures. Ribbit efficiently handles imperfections such as indels and substitutions, providing insights into nested and compound TR relationships through detailed motif decomposition. Comparative analyses using simulated data show Ribbit outperforms existing tools like Dot2dot and TRF in terms of runtime and accuracy. Ribbit reports TR loci in the human genome with lower redundancy than TRF and provides resolved TR regions comparable to variation clusters reported in recent catalogues. Therefore, Ribbit can be leveraged to understand the evolution and biology of complex TR regions in large genomes.

bioinformatics↗

Laboratory adaptive evolution of thermotolerance is linked to the evolution of a robust proteostasis in S. cerevisiae

Thermophilic organisms have evolved a proteome that resists thermal denaturation. While the evolution of their complete proteome would require multiple generations, early on, organisms would need to develop strategies to survive at high temperatures despite their thermolabile proteome. We hypothesized that the organisms would do this by reinforcing their proteostasis capacity. We tested this hypothesis using adaptive laboratory evolution of thermotolerance in Saccharomyces cerevisiae and found that the cells reproducibly evolved better proteostasis capacity in short-term evolution experiments. However, rather than improving the global proteostasis capacity, most of the evolved strains demonstrated enhanced capacity to tackle misfolding in the Endoplasmic Reticulum (ER), specifically by increasing their capacity for ER-associated degradation (ERAD). Given the strong selective advantage of these strains, we posit that protein folding in the ER may be exquisitely sensitive to chronic thermal stress and may act as an early indicator for adaptation to higher temperatures.

evolutionary biology↗

Th1 and Th2 cytokines profile of serum samples from dengue positive cases from Northeast India

BackgroundDengue fever is a fast-spreading acute arboviral infection transmitted by a human-Aedes mosquito cycle. Northeastern India is an endemic zone for dengue; regular outbreaks have been reported. However, molecular details of the virus infection in the host have not been established. Studies on dengue immunopathogenesis have primarily utilized data from American and Southeast Asian regions, with insufficient representation from India. ObjectiveThe present study aimed to characterize the Th1/Th2 cytokine expression profiles from dengue cases in different parts of northeastern India. Statistical analysis cum ResultsAmong the panel of Th1/Th2 cytokines, IFN-{gamma}, IL-2, IL-4, IL-5, IL-10, IL-13, and TNF- cytokines are found to be higher in dengue-infected patients. Anti-inflammatory cytokines are somehow regulated differently in male-female patients. ConclusionThis clinical study on dengue patient samples for cytokine profiling revealed distinct cytokine patterns and their regulation, but further investigation is needed to correlate with disease severity to identify potential biomarkers for disease progression.

microbiology↗

A pan-cancer atlas of T cell targets

T-cell-based immunotherapies have revolutionized cancer treatment, yet only a minority of patients are eligible for these approaches, significantly constrained by the limited knowledge of tumor-specific antigens. Here we present ImmunoVerse, a comprehensive map of T cell targets across 21 cancer types, revealing actionable tumor-specific targets in 89% of tumors analyzed. To define the repertoire of actionable T cell targets, we conducted an exhaustive pan-cancer analysis, integrating data from 7,188 RNA-Seq, 1,771 immunopeptidomes from 512 biological samples and 208 single-cell cancer datasets using novel AI methods, and compared these against 17,384 normal samples covering 51 tissues. Our analysis uncovered 62 viable surface protein targets and 28,446 tumor-specific HLA-presented antigens, deriving from 11 distinct molecular events, across 21 tumor types. Among these, we identified 5,928 previously uncharacterized neoantigens, new tumor self-antigens, peptides derived from tumor-specific cryptic ORFs, tumor-associated microbial targets and a novel splicing-derived PMEL peptide (sPMEL) with enhanced abundance and safety compared to the canonical clinical targets. We successfully expanded sPMEL-specific T cells, validating the therapeutic potential of these targets in functional assays. We highlight 153 promising new tumor targets and experimentally validate 19 targets representing six antigen classes. In addition to being the most comprehensive atlas of targets in scope, ImmunoVerse offers the most extensively annotated resource with key parameters for target selection, providing critical insights for therapeutic prioritization and clinical translation. To catalyze therapeutic development, we released our pan-cancer target atlas through an interactive web portal (https://www.immuno-verse.com) and made the accompanying toolkits available to the scientific community. This work redefines the landscape of therapeutic T cell targets and provides a foundational resource to unlock immunotherapy development across multiple cancers previously considered intractable.

cancer biology↗

Mitigating Proinflammatory SASP and DAMP with Urolithin A: A Novel Senomorphic Strategy

Senescent cells are known to contribute to aging and age-related diseases. One key way they influence aging is by secreting senescence-associated secretory phenotype (SASP) factors along with several damage-associated molecular pattern (DAMP) molecules. Consequently, inhibiting SASP and DAMP signaling (senomorphics) has emerged as a therapeutic strategy. Urolithin A (UA), a gut-derived metabolite produced from ellagitannins and ellagic acid found in berries, nuts, and pomegranates, has demonstrated potent anti-inflammatory properties and protective effects against aging and age-related conditions in experimental models. Here we demonstrate that UA lowers the expression and release of pro-inflammatory SASP and DAMP factors at least in part, on the downregulation of cytosolic DNA release and subsequent decrease in cGAS-STING signaling.

cell biology↗

Protocol for assessing DNA damage levels in vivo in rodent testicular germ cells in the Alkaline Comet Assay

Few protocols are available for retrieving male germ cell-specific information on DNA damage dynamics or assessing the potential harmful effects of environmental contaminants, drugs, or lifestyle factors related to genotoxicity. Here, we present a protocol for evaluating testicular germ cell genotoxicity using a modified version of the alkaline comet assay in rodent testicular germ cells. The protocol includes experimental design, preparation of testicular cell suspensions, comet analysis, germ cell-specific scoring, and data curation methods to collect information on testicular male germ cells, specifically spermatids and primary spermatocytes. For complete details on the use of this protocol please refer to Olsen et al., in preparation HighlightsO_LIDNA damage levels can be specifically measured in testicular germ cells using the developed revised version of the alkaline comet assay C_LIO_LI1C spermatids as well as 4C primary spermatocytes can be assessed C_LIO_LIBoth manual- and modeling-based approaches were developed that facilitate user-friendly protocols to select 1C spermatid comets. C_LIO_LIThis protocol expands the limited methodologies available to study germ cell DNA damage dynamics C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/624648v7_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@1c1e54eorg.highwire.dtl.DTLVardef@b569e9org.highwire.dtl.DTLVardef@3c74adorg.highwire.dtl.DTLVardef@110122e_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO C_FIG

pharmacology and toxicology↗

ELONGATED HYPOCOTYL 5 regulates light-mediated squalene biosynthesis and development in Arabidopsis thaliana

Terpenoids are diverse groups of metabolite families that are crucial for plant development and required in cosmetics and pharmacological industries. Various development processes and environmental factors, including light, have been shown to affect terpenoid biosynthesis. However, regulatory factors involved in such regulation have not been explored much. Squalene synthases (SQSs), key enzymes in the terpenoid pathway, are pivotal for sterol and triterpene biosynthesis across various organisms. In this study, we report that AtSQS1 expression and squalene content are higher in the dark, and light through ELONGATED HYPOCOTYL 5 (HY5) negatively regulates the AtSQS1 gene and squalene biosynthesis in Arabidopsis thaliana. Our study shows that the AtSQS1 gene is unaffected in the hy5-215 mutant during light and dark conditions, but it is down-regulated in WT and HY5OX lines. The histochemical GUS assays and GFP expression patterns indicate a negative regulation of squalene biosynthesis by AtHY5. Yeast one-hybrid assays, EMSA, and ChIP experiments have confirmed the physical binding of AtHY5 on light-responsive elements of the AtSQS1 promoter. We have validated our results by developing AtSQS1 promoter: reporter transgenic lines in WT, hy5-215 mutants, and HY5OX backgrounds and conducted expression, metabolite quantification, and histochemical GUS assays. The metabolites quantification of squalene and phytosterols through GC-MS further confirms that AtHY5 negatively regulates the squalene biosynthesis in a light-dependent manner in Arabidopsis.

plant biology↗

Cryo-EM structures of engineered Shiga toxin-based immunogens capable of eliciting neutralizing antibodies with therapeutic potential against Hemolytic Uremic Syndrome

Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is a serious disease that causes renal failure predominantly in children. Despite its significant impact, there are currently no licensed vaccines or effective therapies available. The B subunits of Shiga toxins 1 and 2 (Stx1B and Stx2B) are suitable targets for developing neutralizing antibodies, but their pentameric assembly is unstable when isolated from the whole toxin. Taking advantage of the oligomeric symmetry shared between Stx1B and Stx2B with the lumazine synthase from Brucella spp. (BLS), we have previously engineered the chimeric toxoids BLS-Stx1B and BLS-Stx2B as immunogens to generate therapeutic equine polyclonal antibodies. The resulting product (INM004) has successfully passed phases 1 and 2 clinical trials, and a phase 3 has been launched in Argentina and seven European countries. In this work, we present the cryo-EM structures of BLS-Stx1B and BLS-Stx2B, which confirm that these engineered immunogens effectively stabilize the StxB pentamers. Moreover, our results reveal that both chimeric constructs present high flexibility at their extremes, corresponding to motions of the StxBs with respect to the BLS core. Additionally, we present structural evidence of the interaction between the chimeras and polyclonal Fab (pFab) fragments derived from INM004, demonstrating that the elicited neutralizing antibodies block most of the interaction surface of the toxins with their cellular receptors. These findings further validate this promising antibody-based therapy for mitigating STEC-HUS and demonstrate that the BLS-Stx1B and BLS-Stx2B chimeras are potential candidates for developing a human vaccine.

immunology↗

Inhibition of the metalloprotease ADAM19 as a Novel Senomorphic Strategy to Ameliorate gut permeability and senescence markers by modulating senescence-associated secretory phenotype (SASP)

Accumulation of DNA damage can accelerate aging through cellular senescence. Previously, we established a Drosophila model to investigate the effects of radiation-induced DNA damage on the intestine. In this model, we examined irradiation-responsive senescence in the fly intestine. Through an unbiased genome-wide association study (GWAS) utilizing 156 strains from the Drosophila Genetic Reference Panel (DGRP), we identified meltrin {beta} (the drosophila orthologue of mammalian ADAM19) as a potential modulator of the senescence-associated secretory phenotype (SASP). Knockdown of meltrin {beta} resulted in reduced gut permeability, DNA damage, and expression of the senescence marker {beta}-galactosidase (SA-{beta}-gal) in the fly gut following irradiation. Additionally, inhibition of ADAM19 in mice using batimastat-94 reduced gut permeability and inflammation in the gut. Our findings extend to human primary fibroblasts, where ADAM19 knockdown or pharmacological inhibition decreased expression of specific SASP factors and SA-{beta}-gal. Furthermore, proteomics analysis of the secretory factor of senescent cells revealed a significant decrease in SASP factors associated with the ADAM19 cleavage site. These data suggest that ADAM19 inhibition could represent a novel senomorphic strategy.

molecular biology↗