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Haldar, S.

Publications and source records attributed to Haldar, S..

At least 19 recordsLinked to original sources

Identification of Novel Inhibitors of JEV RdRp as Potent Antiviral Drugs: Targeting NS5-NS3 Protein Interaction

Japanese Encephalitis Virus (JEV) belongs to the Flavivirus family, and the RNA dependent RNA polymerase (RdRp) domain located at the C terminus of non structural protein 5 (NS5) regulates de novo viral genome synthesis. The conserved priming loop inserted in the thumb domain of RDRP initiates de novo genome synthesis. Interestingly, the reported replication process initiates with an interaction between NS5 (methyltransferase/RDRP) and NS3 (protease/helicase), and inhibiting this interaction directly correlates with the inhibition of viral replication. The function of the priming loop in the context of the NS5 NS3 interaction is not yet known. In this study, we studied the priming loop function in the NS5 NS3 interaction and viral replication. Using a structure based drug design approach, we screened the Maybridge compound library against the RdRp priming loop and identified 15 candidate compounds based on binding energy. Among them, DSHS00151 showed significant dose dependent inhibition of the NS5 NS3 interaction with an IC50 of 3.5 micromolar in the mammalian two hybrid assay, inhibited viral infectivity with an IC50 of 2.54 micromolar, and reduced viral RNA load with an IC50 of 2.9 micromolar, compared to CD10712. Molecular Dynamics (MD) simulations revealed that DSHS00151 exhibits stronger and more stable binding with the priming loop residues (790 to 812) compared to CD10712. The molecular mechanism suggested by the docking of the NS5 and NS3 proteins showed that the priming loop tends to rotate toward the NS3 protein to stabilize the complex, and compound binding restricts this loop rotation, thus compromising the stability of the NS5 and NS3 complex and affecting viral replication. Overall, our study validated the function of the NS5 priming loop as an allosteric site, and compounds binding to this allosteric site belong to the Non Nucleoside Reverse Transcriptase Inhibitors (NNRTI) class of inhibitors, which disrupt the NS5 and NS3 interaction and could be developed as novel anti JEV therapeutics.

pathology↗

Host cell plasma membrane-derived vesicles efficiently inhibit in vitro Influenza A virus infection in a size-dependent manner

The influenza virus poses a significant global health threat due to its continuous evolution, immune evasion, and zoonotic spillover. The rise of drug resistance, reduced susceptibility to existing antiviral medications, and the limited effectiveness of annual vaccines underscore the need for new antiviral strategies. To infect, the influenza virus binds to sialic acid (SA)-containing molecules on host cell membranes through hemagglutinin (HA). Blocking this interaction represents a promising antiviral approach. Herein, we report that SA containing plasma membrane-derived vesicles (PMV) efficiently inhibits in vitro Influenza A virus (IAV) infection. Using orthogonal methods, we demonstrate that PMV derived from A549, MDCK, and HEK cells competitively bind to H1N1 (WSN) and H3N2 (X-31) IAV strains, block entry and infection in human respiratory epithelial cells in a dose-dependent manner, without causing significant toxicity. When the size of the vesicles was reduced through extrusion, the antiviral activity was enhanced, and this was found to be correlated with a size-dependent increase in hemagglutination inhibition and reduced IAV internalisation. Plasma membrane-derived vesicles may serve as a novel antiviral strategy against influenza virus infections due to their simple production method and conserved SA binding site on HA.

biochemistry↗

Tryptophan-aspartic acid containing peptide analog from coronin 1 inhibits model membrane fusion and enveloped viral infection in cells

Membrane fusion is a crucial step in the infection cycle of an enveloped virus, and the development of fusion inhibitors could lead to broad-spectrum antivirals beyond the one-bug-one-drug paradigm. In our continued effort to design peptide-based fusion inhibitors that block fusion by modulating membrane physical properties rather than targeting viral proteins, we have designed a tryptophan-aspartic acid (WD) containing peptide analog, mGG21, from coronin 1. Coronin 1 has been implicated in preventing the fusion of live mycobacteria containing phagosomes with lysosomes. The mGG-21 displays around 60% inhibition in fusion pore formation (complete fusion) in model membranes by increasing the acyl chain ordering of the membrane, regardless of the cholesterol content of the membrane, unlike previously designed predecessors with 20-30 % inhibition activity. Further, we show that mGG-21 inhibits Influenza and Chikungunya virus infection in cellular models without exerting any toxicity. Taken together, our findings underscore the importance of WD repeats in designing broad-range viral fusion inhibitors.

biophysics↗

Robust Prediction of Patient-Specific Cancer Hallmarks Using Neural Multi-Task Learning: a model development and validation study

BackgroundAccurate quantification of cancer hallmark activity is essential for understanding tumor progression, tailoring treatments, and improving patient outcomes. Traditional methods, such as histopathological grading and immunohistochemistry for protein expression, often overlook the complex interplay between cancer cells and the tumor microenvironment and provide limited insight into hallmark-specific mechanisms. We aimed to develop OncoMark, a high-throughput deep learning-enabled neural multi-task learning framework capable of systematically quantifying integrative hallmarks activities using transcriptomics data from routine tumor biopsies. MethodsIn this study, we acquired single-cell transcriptomics data from 941 tumor samples across 14 tissue types, comprising nearly 3.1 million cells from 56 studies conducted worldwide, to form a large multicenter dataset. Our model employs a supervised neural multi-task learning method designed to predict multiple cancer hallmarks present in the biopsy samples simultaneously. The OncoMark model was developed and tested on 90% of the studies (patients from 51 studies) using repeated five-fold cross-validation performed twice. For further evaluation, the model was assessed on the remaining 10% of the studies (patients from 5 studies) that were excluded from the initial training and testing dataset. Additionally, we included patients from publicly available datasets, including TCGA, GTEx, ANTE, MET500, POG570, CCLE, TARGET, and PCAWG to validate the models performance. The primary objective was to evaluate the performance of the model in identifying cancer hallmarks in cancer datasets and ensure no hallmark predictions were made in normal samples across the four prespecified groups: (i) internal test set, (ii) external test set, (iii) normal samples (real-world), and (iv) cancer samples (real-world). FindingsOncoMark demonstrated exceptional performance in predicting cancer hallmark states, achieving near-perfect accuracy across internal test data and five external test datasets. Internal testing consistently showed accuracy, precision, recall, and F1 scores exceeding 99%, underscoring the models reliability across hallmarks. External test further confirmed these findings, with accuracy, precision, recall, F1 scores, and balanced accuracy consistently exceeding 96{middle dot}6%, and multiple datasets achieving perfect scores, highlighting the models exceptional generalizability and robustness. Specificity tests using GTEx and ANTE datasets accurately classified normal tissues, while sensitivity analysis on TCGA, MET500, CCLE, TARGET, PCAWG, and POG570 datasets effectively identified cancer hallmarks. InterpretationWe developed an AI-based framework that enables accurate, efficient, and cost-effective quantification of cancer hallmark activity directly from transcriptomics data. The framework demonstrated significant potential as an assistive tool for guiding personalized treatment strategies and advancing the clinical management of cancer patients. FundingAshoka University, S.N. Bose National Centre for Basic Sciences, Mphasis F1 Foundation, DST SERB Core Research Grant. Research in ContextO_ST_ABSEvidence before this studyC_ST_ABSWe conducted an extensive literature search using Google Scholar and PubMed without language restrictions, employing search terms such as "(Predicting OR Classifying OR Annotating) and (cancer hallmarks) AND (Deep OR Machine Learning) OR (Artificial Intelligence OR AI)." While there have been advancements in molecular oncology and computational methodologies over the two decades since the concept of cancer hallmarks was first introduced, a comprehensive machine learning or deep learning framework to annotate all cancer hallmarks simultaneously from tumor biopsy samples remains to be developed. Additionally, the scarcity of hallmark-annotated datasets has posed a significant challenge, hindering the development of robust predictive models. Added value of this studyThis study introduces OncoMark, a novel high-throughput neural multi-task learning (N-MTL) framework designed to predict all cancer hallmark activities simultaneously from biopsy samples. OncoMark addresses the lack of annotated hallmark-specific data by generating synthetic biopsy (pseudo-bulk) datasets annotated with hallmark activity, meticulously modeled to reflect real-world tumor biology while maintaining clinical relevance. The framework employs a multi-task learning approach to capture interdependencies among hallmarks, advancing beyond isolated predictions to offer a holistic view of tumor biology. Validation on five independent datasets comprising 95 patient samples demonstrated its generalizability and reproducibility. Further external validation using eight datasets, encompassing over 11,679 cancer and 8348 normal patient samples, reinforced its robustness. To promote clinical integration, a user-friendly web-based tool was developed, enabling seamless access for oncologists and researchers. Implications of all the available evidenceThe OncoMark framework represents a transformative advancement in cancer diagnostics and treatment planning. By enabling accurate and reproducible prediction of all hallmark activities simultaneously from biopsy samples, this model paves the way for precision oncology at scale. Its ability to systematically capture hallmark interdependencies provides deeper insights into tumor behavior, guiding the development of individualized targeted therapies. The incorporation of a web-based interface ensures the accessibility of this innovation to clinicians worldwide, bridging the gap between computational oncology and clinical practice. Following further validation and integration into healthcare workflows, OncoMark has the potential to improve cancer outcomes by delivering timely, cost-effective, and precise tumor analyses, facilitating informed therapeutic decision-making with unparalleled precision. Cancer progression is driven by a set of well-defined biological principles--collectively termed the "hallmarks of cancer"--yet current diagnostic approaches seldom incorporate these distinct molecular features into clinical practice. Despite substantial progress in molecular oncology, traditional methods like histopathological grading and immunohistochemical assays often fail to capture the complex interplay between cancer cells and the tumor microenvironment, emphasizing the need for robust computational frameworks capable of systematically quantifying hallmark-specific activity. Here, we address this gap by developing OncoMark, a high-throughput neural multi-task learning (N-MTL) framework designed to simultaneously quantify hallmark activities in tumor biopsies using transcriptomics data. We show that OncoMark achieves near-perfect accuracy, precision, recall, and F1 scores (>99%) in cross-validation, with external validation consistently exceeding 96.6% on five independent datasets. Further evaluation on eight additional datasets--including large-scale cancer cohorts (TCGA, MET500, CCLE, TARGET, PCAWG, POG570) and normal tissue datasets (GTEx, ANTE)--demonstrated high specificity for normal samples and robust sensitivity for hallmark prediction in cancer. By delivering a comprehensive and cost-effective molecular portrait of tumor biology and providing a user-friendly web platform accessible at https://oncomark-ai.hf.space/, OncoMark has the potential to guide tailored treatment strategies and advance precision oncology. More broadly, this framework signifies a transformative step toward routine hallmark-based diagnostics, promising to improve patient outcomes by facilitating timely and precise tumor profiling.

cancer biology↗

The Novel Chaperone Activity of p47 Modulates Force-Mediated Retrotranslocation from the Endoplasmic Reticulum to the Cytosol

Protein quality control in the endoplasmic reticulum (ER) maintains cellular proteostasis by regulating protein folding, assembly, and degradation. While protein translocation from the cytosol into the ER is well-studied, the reverse process, known as retrotranslocation, which exports proteins from the ER lumen or membrane into the cytosol, is less understood. In this study, we investigate the role of p47, a cofactor of the ATPase p97, in retrotranslocation and its chaperone-like activity on the model substrate talin using single-molecule magnetic tweezers. We find that p47 enhances the mechanical stability of talin, by increasing its folding probabilities by 8 pN, which generate a maximum work output of up to [~]199.5 zJ to facilitate the extraction of the protein from the ER lumen. These findings suggest that p47 interacts with substrates emerging from the ER, generating pulling forces that aid retrotranslocation, which uncovers a novel mechanistic role for p47 in ER-associated degradation, advancing the understanding of retrotranslocation.

biophysics↗

25 Hydroxy Cholesterol Effectively Inhibits Japanese Encephalitis Virus Infection in Vero Cells

The Japanese encephalitis virus (JEV) is a mosquito-borne, enveloped flavivirus that causes acute encephalitis. Although JEV is increasingly recognized as a global threat, there is currently no FDA-approved treatment available for JEV. 25-hydroxycholesterol (25-HC) is an oxysterol produced through the oxidation of cholesterol, a process catalyzed by cholesterol 25-hydroxylase (CH25H), which is an interferon-stimulated gene that is upregulated during viral infections. In this study, we report for the first time that 25-HC effectively prevents JEV infection in cells. Our results show that 25-HC inhibits JEV infection in Vero cells with an IC50 of [~] 4.18 {micro}M, while displaying no cell toxicity (CC50 > 50 {micro}M). In addition, we show that RNA level of the JEV envelope (E) protein exhibits a dose-dependent reduction in the presence of 25 HC, which is further supported by the concomitant decrease of the E protein expression. We surmise that the anti-JEV properties of 25 HC stem from its effects on the host plasma membrane organization and dynamics by modulating membrane cholesterol level, which may impair the entry and fusion of JEV. Given the antiviral effects of 25HC against Zika and Dengue viruses, our findings suggest that 25-HC could be a promising candidate for developing broad-spectrum anti-flaviviral therapeutics.

biochemistry↗

Mechanistic Insights into Periplasmic Chaperones as Regulators of Protein Folding and Translocation in Gram-Negative Bacteria

In Gram-negative bacteria, periplasmic chaperones mediate the transport and folding of outer membrane proteins. While their substrate interaction mechanisms are well studied, their functional cycle during periplasmic translocation remains unclear. Using single-molecule force spectroscopy, we demonstrate that SecYEG-associated chaperones PpiD and DsbC act as foldases, delivering up to 45.5 zJ of mechanical work. This activity facilitates substrate extraction from the SecYEG translocation tunnel, reducing ATP consumption during SecA-mediated translocation. In contrast, chaperones such as Spy and Skp function as holdases, stabilizing unfolded substrates to prevent misfolding during translocation. Our findings reveal a unique mechanism by which chaperones adapt to mechanical constraints, optimizing protein folding and translocation in the periplasm.

biophysics↗

Comprehensive Enumeration of Cancer Stem-like Cell Heterogeneity Using Deep Neural Network

Cancer stem cells (CSCs), a distinct subpopulation within tumors, are pivotal in driving treatment resistance and tumor recurrence, posing substantial challenges to conventional therapeutic strategies. Precise quantification and profiling of these cells are essential for improving cancer treatment outcomes. We present ACSCeND, an advanced deep neural network model accompanied by a robust workflow, specifically developed to quantify cellular compositions from bulk RNA-seq data, enabling accurate CSC profiling. By integrating bulk RNA-seq data with insights derived from single-cell RNA-seq datasets, ACSCeND effectively captures the diversity and hierarchical organization of tumor-resident cell states, alongside cell-specific gene expression profiles (GEPs). Compared to current tissue deconvolution models, ACSCeND exhibits superior performance, achieving significantly higher Concordance Correlation Coefficient (CCC) values and lower Root Mean Square Error (RMSE) across various pseudobulk and real-world bulk tissue samples. Application of ACSCeND to TCGA and PRECOG datasets reveals a strong association between CSC abundance and poorer disease-free survival outcomes, underscoring the clinical relevance of CSCs in cancer progression. Furthermore, cell-specific GEPs for distinct CSC states unveil novel molecular signatures and illuminate the origins of CSC-driven tumor heterogeneity. In summary, ACSCeND provides a powerful, scalable platform for high-throughput quantification of cellular compositions and distinct potency states within normal tissues as well as highly heterogeneous tissues, such as tumors.

genomics↗

Genomic Reconstruction and Dietary Response Assessment of Three Acutalibacteraceae Bacteria Isolated from Fecal Samples of Singapore Subjects.

1.Clostridium leptum, a key player in gut butyrate production, has a profound impact on various facets of intestinal health. A recent clinical trial highlighted a significant increase in the relative abundance of this species in response to dietary interventions using beneficial oils. We isolated microbial strains corresponding to "Clostridium leptum" (at the 16S rRNA gene similarity level) and sequenced their genomes. All three genomes were successfully reconstructed, maintaining the chromosome as a single contig. Subsequent genome-wide analysis unveiled the phylogenetic diversity of the isolates, including the discovery of a new species - Gallacutalibacter singaporense. Based on the reconstructed metabolic model, we predicted the growth condition patterns of this new species and confirmed the predictions in vitro. Leveraging the assembled genomes, we dissected the components of the strong dietary intervention response signal previously ascribed to "C. leptum" and revealed distinct individual dynamics of all three bacteria in the clinical trial context. The transitional behavior of the novel species, in particular, revealed intriguing patterns, blazing the path to uncovering previously unrecognized interactions along the diet - gut microbiome - human health axis.

microbiology↗

Developing peptide-based fusion inhibitors as an antiviral strategy utilizing Coronin 1 as a template

Enveloped viruses can enter the host cells by endocytosis and subsequently fuse with the endosomal membranes, or fuse with the plasma membrane at the cell surface. The crucial stage of viral infection, regardless of the route taken to enter the host cell, is membrane fusion. The present work aims to develop a peptide-based fusion inhibitor that prevents membrane fusion by modifying the properties of the participating membranes, without targeting a protein. This would allow us to develop a fusion inhibitor that might work against a larger spectrum of enveloped viruses as it does not target any specific viral fusion protein. With this goal, we have designed a novel peptide by modifying a native sequence derived from coronin 1, a phagosomal protein, that helps to avoid lysosomal degradation of mycobacterium-loaded phagosomes. The designed peptide, mTG-23, inhibits [~] 30-40% fusion between small unilamellar vesicles containing varying amounts of cholesterol by modulating the biophysical properties of the participating bilayers. As a proof of principle, we have further demonstrated that the mTG-23 inhibits Influenza A virus infection in A549 and MDCK cells (with[~] EC50 of 20.45 {micro}M and 21.45 {micro}M, respectively), where viral envelope and endosomal membrane fusion is a crucial step. Through a gamut of biophysical and biochemical methods, we surmise that mTG-23 inhibits viral infection by inhibiting viral envelope and endosomal membrane fusion. We envisage that the proposed antiviral strategy can be extended to other viruses that employ a similar modus operandi, providing a novel pan-antiviral approach.

biophysics↗

Unravelling Antibody-Induced Mechanical Stability of Antigen: Insights from Single-Molecule Studies

The intricate nature of antigen-antibody interactions plays a pivotal role in immunological responses. Despite the multitude of ligand-binding sites on antigens, the influence of antibodies on their mechanical stability remains elusive. This study elucidates the impact of IgM, the largest antibody isotype, on the mechanical stability of protein L, a bacterial superantigen, using single-molecule magnetic tweezers and steered molecular dynamics. Our findings reveal a concentration-dependent elevation in mechanical stability induced by IgM, as demonstrated by prolonged unfolding dwell times. Through steered molecular dynamics simulations, we elucidate the distinct mechanical responses of protein L binding interfaces at various IgM complex states, highlighting their synergistic effect on IgM dimer complex stability. Notably, this enhanced response stems from the altered unfolding pathway of protein L upon IgM interaction, providing significant insights into the generic mechanisms governing antibody-induced mechanical stability of antigenic substrates in physiological conditions, shedding light on the underlying folding dynamics and molecular mechanics of antigen-antibody interaction.

biophysics↗

Next-Gen Profiling of Tumor-resident Stem Cells using Machine learning

Tumor-resident stem cells, also known as cancer stem cells (CSCs), constitute a subgroup within tumors, play a crucial role in fostering resistance to treatment and the recurrence of tumors, and pose significant challenges for conventional therapeutic methods. Existing approaches for identifying CSCs face notable hurdles related to scalability, reproducibility, and technical consistency across different cancer types due to the adaptable nature of CSCs. In this context, we introduce OSCORP, an innovative machine-learning-driven approach. This methodology quantifies and identifies CSCs, achieving almost 99% accuracy using biopsy bulk RNAseq data. OSCORP leverages genetic similarities between normal and cancer stem cells. By categorizing CSCs into four distinct yet dynamic potency states, this approach provides insights into the differentiation landscape of CSCs, unveiling previously undisclosed facets of tumor heterogeneity. In evaluations conducted on patient samples across 22 cancer types, OSCORP revealed clinical, transcriptomic, and immunological signatures associated with each CSC state. It has emerged as a comprehensive tool for understanding and addressing the complexities of cancer stem cells. Ultimately, OSCORP opens up new possibilities for more effective personalized cancer therapies and holds the potential to serve as a clinical tool for monitoring patient-specific CSC changes during treatment or follow-up care.

cancer biology↗

Methotrexate-modulated talin-dynamics drives cellular mechanical phenotypes via YAP signalling

Methotrexate is a well-known antineoplastic drug used to prevent cancer aggravation. Despite being a targeted therapeutic approach, its administration comes with the risk of cancer recurrence, plausibly through its proven off-target effect on focal adhesions. Since FA dynamics is dependent on force transmission through its constituent proteins, including talin, methotrexate might affect the mechanical activity of these proteins. Here we have combined single-molecule studies, computational dynamics, cell-based assays, and genomic analysis to unveil the focal adhesion-regulating role of methotrexate central to its effect on talin dynamics and downstream pathways. Interestingly, our single-molecule force spectroscopic study shows that methotrexate modulates the bimodal force distribution of talin in a concentration-dependent manner. Steered molecular dynamics reveal that methotrexate-talin interactions alter talin mechanical stability exposing their vinculin binding sites. Finally, we found that methotrexate-regulated talin-dynamics remodel cancer cell mechanical phenotypes like cell polarity, adhesion, and migration by regulating talin-vinculin association-mediated YAP signaling. These results further correlate with genomic analysis of methotrexate-treated patients, demonstrating its clinical importance. Taken together, these findings disseminate the effects of methotrexate-modulated mechanosensitivity of adhesion proteins on cellular events.

cell biology↗

Force-regulated chaperone activity of BiP/ERdj3 is opposite to their homologs DnaK/DnaJ: explained by strain energy

Polypeptide chains experiences mechanical tension while translocating through cellular tunnel. In this scenario, interaction of tunnel-associated chaperones with the emerging polypeptide occurs under force; however, this force-regulated chaperone behaviour is not fully understood. We studied the mechanical chaperone activity of two tunnel-associated chaperones BiP and ERdj3 both in the absence and presence of force; and compared to their respective cytoplasmic homologs DnaK and DnaJ. We found that BiP/ERdj3 shows strong foldase activity under force; whereas their cytoplasmic homolog DnaK/DnaJ behave as holdase. Importantly, these tunnel-associated chaperones (BiP/ERdj3) revert to holdase in the absence of force, suggesting that mechanical chaperone activity differs depending on the presence or absence of force. This tunnel-associated chaperone-driven folding event generates additional mechanical energy of up to 54 zJ that could help protein translocation. The mechanical-chaperone behaviour can be explained by strain theory: chaperones with higher intrinsic deformability function as mechanical foldase (BiP, ERdj3), while chaperones with lower intrinsic deformability act as holdase (DnaK and DnaJ). Our study thus unveils the underlying mechanism of mechanically regulated chaperoning activity and provides a novel mechanism of co-translocational protein folding. SignificanceThe mechanical-activity of chaperones, located at the edge of a tunnel, could be different from their cytoplasmic homologs. Translocating substrates within the tunnel are known to experience mechanical constraints, whereas the cytosolic substrates interact with the chaperones in the absence of force. To understand this phenomenon, we investigated two tunnel-associated chaperones BiP/ERdj3 and their cytosolic homologs-DnaK/DnaJ. We observed that BiP/ERdj3 possess strong foldase activity while their substrates are under force; whereas DnaK/DnaJ possess holdase function. Notably all these chaperones function as holdase in the absence of force, which suggest that mechanical chaperone activity is different with and without force. We explained this mechanical behaviour using strain theory, providing a physical mechanism of chaperone-assisted co-translocational protein folding.

biophysics↗

Molecular mechanisms of coronary artery disease risk at the PDGFD locus

Platelet derived growth factor (PDGF) signaling has been extensively studied in the context of vascular disease, but the genetics of this pathway remain to be established. Genome wide association studies (GWAS) for coronary artery disease (CAD) have identified a risk locus at 11q22.3, and we have verified with fine mapping approaches that the regulatory variant rs2019090 and PDGFD represent the functional variant and putative functional gene. Further, FOXC1/C2 transcription factor (TF) binding at rs2019090 was found to promote PDGFD transcription through the CAD promoting allele. Employing a constitutive Pdgfd knockout allele along with SMC lineage tracing in a male atherosclerosis mouse model we mapped single cell transcriptomic, cell state, and lesion anatomical changes associated with gene loss. These studies revealed that Pdgfd promotes expansion, migration, and transition of SMC lineage cells to the chondromyocyte phenotype and vascular calcification. This is in contrast to protective CAD genes TCF21, ZEB2, and SMAD3 which we have shown to promote the fibroblast-like cell transition or perturb the pattern or extent of transition to the chondromyocyte phenotype. Further, Pdgfd expressing fibroblasts and pericytes exhibited greater expression of chemokines and leukocyte adhesion molecules, consistent with observed increased macrophage recruitment to the plaque. Despite these changes there was no effect of Pdgfd deletion on SMC contribution to the fibrous cap or overall lesion burden. These findings suggest that PDGFD mediates CAD risk through promoting SMC expansion and migration, in conjunction with deleterious phenotypic changes, and through promoting an inflammatory response that is primarily focused in the adventitia where it contributes to leukocyte trafficking to the diseased vessel wall.

genetics↗

Pan-cancer Analysis Predicts Kindlin-associated Global Mechanochemical Perturbation

Kindlins are mechanosensitive adapter proteins that connect extracellular mechanical cues to intracellular chemical events. Any alterations in these proteins thus alter cellular signaling, which could result in cancer progression. However, their involvement in global mechanochemical signals remains elusive in cancers. Here we analyze pan-cancer samples to decipher how kindlin alterations aid cancer progression. We show that kindlin alterations, at both the genetic and mRNA level, dysregulates cellular behavior which significantly correlate with poor survival. We find that while these alterations are cancer-specific, they are prevalent in advanced tumor stages and metastatic onset. We observe that kindlins co-alter with a substantial fraction of human mechanochemical proteome in various tumors. Our analysis suggests how kindlin alterations aid tumor-promoting signals with a synergistic effect from alterations of cancer-hallmark genes. Notably, we demonstrate a consistent alteration of epithelial-mesenchymal-transition markers with kindlin activity. Overall, our study highlights how kindlin alterations could affect metabolism, genomic instability, and signal disruption via their interactome network, causing cancer and suggests targeting them as a therapeutic strategy.

cancer biology↗

Trimethylamine N-oxide (TMAO) enhances substrate mechanical stability probed by single molecule magnetic tweezers

Trimethylamine N-oxide (TMAO) is a well-known osmolyte to stabilize the folded proteins through a variety of mechanisms. Since mechanical strength of proteins is a critical determinant of its stabilization, TMAO might play a relevant role by favoring its folding dynamics or by enhancing its mechanical stability. To address this question, we have performed the single-molecule magnetic tweezers experiment to explore the TMAO effect on two structurally distinct substrates-protein L and talin. We observed that TMAO increases the mechanical stability of these proteins through increasing their unfolding force. Additionally, we are able to demonstrate that TMAO retards the unfolding kinetics, while accelerating the refolding kinetics under force; which eventually tilts the energy landscape towards the folded state. Interestingly, this TMAO-enhanced protein folding generates mechanical work output upto [~]67 zJ, allowing the protein folding under higher force regime. Overall this TMAO-enhanced mechanical stability provides a significant implication to folding-induced structural stability of proteins.

biophysics↗

Talin-drug interaction reveals a key molecular determinant for biphasic mechanical effect: studied under single-molecule resolution

Talin as an adhesion protein, exhibits a strong force-dependent structure-function dynamics. Being a mechanosensitive focal adhesion (FA) protein, talin might interact to several FA targeting drugs; however, the molecular mechanism of talin-drug interactions remains elusive. Here we combined magnetic tweezers and molecular dynamics (MD) simulation to explore mechanical stability of talin with three drugs based on their talin specificity. Interestingly, our study revealed that talin displays a bimodal force distribution with a low and high unfolding force population. We observed that talin nonspecific drugs (tamoxifen and letrozole) display biphasic effect: increase talin mechanical stability upto optimum concentration, followed by a decrease in stability with further concentration increase. By contrast, talin-specific cyanidin 3-O-glucoside promotes a steady increase to talin mechanical stability with its concentration. We reconciled our observation from the simulation study: tamoxifen enters into talin hydrophobic core, eventually destabilizing the protein; whereas cyanidin 3-O-glucoside stabilizes the protein core by maintaining the inter-helix distance. Finally, we observed a strong correlation among hydrophobicity and cavity analysis, illustrating a detailed mechanistic analysis of drug effect on the mechanosensitive protein. Overall this study presents a novel perspective for drug designing against mechanosensitive proteins and studying off-target effects of already known drugs.

biophysics↗