bioRxiv Science⌕ Search

Biology subjects

Basu, S.

Publications and source records attributed to Basu, S..

At least 55 records · Page 3Linked to original sources

AlphaGenome: advancing regulatory variant effect prediction with a unified DNA sequence model

Deep learning models that predict functional genomic measurements from DNA sequence are powerful tools for deciphering the genetic regulatory code. Existing methods trade off between input sequence length and prediction resolution, thereby limiting their modality scope and performance. We present AlphaGenome, which takes as input 1 megabase of DNA sequence and predicts thousands of functional genomic tracks up to single base pair resolution across diverse modalities - including gene expression, transcription initiation, chromatin accessibility, histone modifications, transcription factor binding, chro- matin contact maps, splice site usage, and splice junction coordinates and strength. Trained on human and mouse genomes, AlphaGenome matches or exceeds the strongest respective available external models on 24 out of 26 evaluations on variant effect prediction. AlphaGenomes ability to simultaneously score variant effects across all modalities accurately recapitulates the mechanisms of clinically-relevant variants near the TAL1 oncogene. To facilitate broader use, we provide tools for making genome track and variant effect predictions from sequence.

bioinformatics↗

Oral octanoylcarnitine alleviates exercise intolerance in mouse models of long-chain fatty acid oxidation disorders

Long-chain fatty acid oxidation disorders (LC-FAODs) cause energy deficits in heart and skeletal muscle that is only partially corrected by current medium-chain lipid therapies such as triheptanoin. We find that heart and muscle lack medium-chain acyl-CoA synthetases, limiting the capacity for {beta}-oxidation of medium-chain fatty acids. Instead, heart and muscle mitochondria robustly respire on medium-chain acylcarnitines. The mitochondrial matrix enzyme carnitine acetyltransferase (CrAT) efficiently converts orally delivered octanoylcarnitine (C8-carnitine) to octanoyl-CoA for energy generation. C8-carnitine exhibits twice the oral bioavailability of triheptanoin and distributes to muscle and heart. A single oral dose markedly enhances grip strength, basal locomotion, and treadmill endurance while attenuating lactate and creatine kinase elevations in multiple mouse models of LC-FAODs. Thus, medium-chain acylcarnitines overcome a previously unrecognized metabolic bottleneck in LC-FAOD muscle and may represent an alternative to triglyceride-based therapies for bioenergetic disorders.

biochemistry↗

Spatial multi-omics and deep learning reveal fingerprints of immunotherapy response and resistance in hepatocellular carcinoma

Despite advances in immunotherapy treatment, nonresponse rates remain high, and mechanisms of resistance to checkpoint inhibition remain unclear. To address this gap, we performed spatial transcriptomic and proteomic profiling on human hepatocellular carcinoma tissues collected before and after immunotherapy. We developed an interpretable, multimodal deep learning framework to extract key cellular and molecular signatures from these data. Our graph neural network approach based on spatial proteomic inputs achieved outstanding performance (ROC-AUC > 0.9) in predicting patient treatment response. Key predictive features and associated spatial transcriptomic profiles revealed the multi-omic landscape of immunotherapy response and resistance. One such feature was an interface niche expressing restrictive extracellular matrix factors that physically separates tumor tissue and lymphoid aggregates in nonresponders. We integrate this and other spatially-resolved signatures into SPARC, a multi-omic "fingerprint" comprising scores for immunotherapy response and resistance mechanisms. This study lays groundwork for future patient stratification and treatment strategies in cancer immunotherapy.

cancer biology↗

Clade I TGA transcription factors are negative regulators of sulfate uptake and metabolism

Increasing crop nutrient use efficiency can have dual impact; it can significantly reduce costs for fertilizers and mitigate global environmental repercussions caused by nutrient leakage. Understanding nutrient crosstalk in light of global environmental changes is crucial for improving nutrient use efficiency and food security. Here we show that provision of nitrate, but not ammonium, induces sulfate uptake and assimilation. We reveal that TGA1 and TGA4 are negative regulators of sulfate uptake, while other TGAs and the nitrate receptors NRT1.1 and NLP7 are not involved in this regulation. Our results show that TGA1 and TGA4 negatively regulate a larger set of genes involved in S signaling and metabolism, not only under nitrate provision, but also under S-deficiency. Under long-term S-deficiency, tga1 tga4 mutant had increased Cys levels in the shoots and showed better fitness. Additionally, TGA1 and TGA4 play a negative role in pathogen-induced indolic GSLs synthesis under sulfate deficiency. Similarly, clade I TGA TFs negatively regulate camalexin accumulation under pathogenic bacteria infection. Together, our findings suggest that TGA1 and TGA4 play an important role in the crosstalk of nitrate signaling with sulfate metabolism, and affect the function of S-metabolites in the interaction with pathogenic bacteria.

plant biology↗

Mesoglea biogenesis reveals a cryptic aboral valve for pressure regulation in cnidarian morphogenesis

Cnidarians are classically defined by a single oral opening, a hallmark of the "blind gut" model in early animal evolution. Here, we identify a pressure-sensitive aboral valve in Nematostella vectensis that operates independently of digestion. This valve dissipates elevated hydraulic pressure during morphogenesis, by expelling fluid through transient epidermal ruptures triggered by muscular ring opening. This unexpected function emerged from a comprehensive analysis of mesogleal basement membrane biogenesis. We show that the global dynamics of this extracellular matrix transduce muscular hydraulics to drive tissue rearrangement and stabilize shape, while localized FGFRb-dependent matrix remodeling establishes the aboral valve. By positioning the mesoglea as an integrator of biomechanics, tissue remodeling, and aboral valve function, these findings expand non-bilaterian openings beyond the digestive paradigm as a hydraulic regulator.

developmental biology↗

3D osteocyte networks under Pulsatile Unidirectional Fluid Flow Stimuli (PUFFS)

Although osteocytes are known to play a key role in skeletal mechano-adaptation, few in vitro models have investigated how pulsatile mechanical stimuli influence the properties of 3D osteocyte networks. Here we design and develop a microfluidic based in vitro model to study 3D osteocyte networks cultured under Pulsatile Unidirectional Fluid Flow Stimuli (PUFFS). Digital light projection stereolithography was used to design and fabricate a three-chambered PDMS microfluidic chip. Model osteocytes (murine MLO-Y4) were encapsulated in collagen matrix within the chip to form self-assembled three-dimensional (3D) cell networks. Daily stimulus in the form of PUFFS was then applied for upto 21 days. A combination of experiments, computational simulation and analytical modeling was used to characterize the mechanical environment experienced by embedded cells during PUFFS. Viability, morphology, cell-connectivity, expression of key proteins, and gene expression, and real-time calcium signaling within 3D osteocyte networks were characterized at select time-points and compared to static conditions. Results show that PUFFS stimulation at 0.33 and 1.66 Hz can initiate mechanotransduction via calcium signals that are propagated across the network of collagen encapsulated osteocytes via Cx43 junctions. Furthermore, osteocytes cultured in these devices maintain expression of several key osteocyte genes for up to 21d. Taken together, this model can potentially serve as a testbed to study how 3D osteocyte networks respond to dynamic mechanical stimulation relevant to skeletal tissues.

bioengineering↗

SieveAI: Development of an Automated extensible and customisable drug discovery pipeline and its validation

Systematic Interaction Evaluation and Virtual Enhancement Analysis Interface (SieveAI) is an automated drug discovery pipeline developed to enhance the efficiency of virtual screening and computer-aided drug discovery processes. The molecular docking workflow encompasses acquiring, modeling, and pre-processing of molecular structure files, conducting docking with various algorithms, and subsequent analysis and interpretation of the outcomes by visualising or tabulating the results. While several open-source software tools are available to assist these operations at different steps of molecular docking, they often necessitate manual user intervention at every stage. To streamline and automate this extensive manual process and develop a comprehensive solution, we have developed an innovative, fully extensible, molecular docking pipeline SieveAI ((C)L-129927/2023). The same has been demonstrated in this manuscript. SieveAI works with a range of open-source libraries, packages, and programs to facilitate automated drug discovery using established programs and software. The package is accessible at https://miRNA.in/SieveAI.

bioinformatics↗

The dichotomous impacts of semaphorin3E deficiency on exacerbating airway hyperresponsiveness, remodelling, and inflammation in type-2 low and type-2 high asthma models

Semaphorin3E has shown promise in alleviating the severity of asthma in preclinical studies; however, its role in the chronic features of type 2-low asthma remains unclear. Therefore, we aimed to investigate the role of Sema3E in a mouse model of severe asthma that exhibits a mix of granulocytic inflammation with neutrophils dominance and compared the results with those from the type-2 high eosinophilic asthma model. Sema3E knockout (KO) and wild-type (WT) mice were subjected to type-2 low and type-2 high regimens using house dust mite (HDM) combined with cyclic-di-GMP or HDM alone, respectively. Airway hyperresponsiveness parameters were measured using the FlexiVent ventilator. Bronchoalveolar lavage fluid cell phenotyping was performed by flowcytometry. Additionally, cytokines and antibodies were quantified using Mesoscale and ELISA. Mucus overproduction and goblet cell hyperplasia were visualized by Periodic-acid-Schiff staining. In comparison to WT mice, Sema3E KO mice exhibited an enhanced tissue resistance and tissue elastance in the type 2-low asthma model. Concurrently, Sema3E KO mice that were subjected to the type-2 low asthma model demonstrated an elevated presence of pulmonary neutrophils, dendritic cells, CD4 T cells, as well as increased levels of IL-17, TNF, IL-1{beta}, CXCL-8, and MCP-1/CCL2 in comparison to their WT counterparts. However, in the type-2 high model, Sema3E KO mice exhibited a significant increase in goblet cell numbers and mucus overproduction, as well as enhancements in the number of eosinophils, IgE-producing B cells, and IL-4 levels compared to WT mice, highlighting the homeostatic role of Sema3E in the distinct immune niche of type-2 low and type-2 high asthma. Overall, our data showed that Sema3E is critical in modulating AHR, airway inflammation, and tissue remodelling in type 2 low and type 2 high phenotypes of asthma. The Sema3E regulatory network varies depending on the immunization regimen, affecting distinct parameters in type-2 low and type-2 high asthma models.

immunology↗

Combining MicroED and native mass spectrometry for structural discovery of enzyme-biosynthetic inhibitor complexes

With the goal of accelerating the discovery of small molecule-protein complexes, we leverage fast, low-dose, event based electron counting microcrystal electron diffraction (MicroED) data collection and native mass spectrometry. This approach resolves structures of the epoxide-based cysteine protease inhibitor, and natural product, E-64, and its biosynthetic analogs bound to the model cysteine protease, papain. The combined structural power of MicroED and the analytical capabilities of native mass spectrometry (ED-MS) allows assignment of papain structures bound to E-64-like ligands with data obtained from crystal slurries soaked with mixtures of known inhibitors, and crude biosynthetic reactions. ED-MS further discriminates the highest-affinity ligand soaked into microcrystals from a broad inhibitor cocktail, and identifies multiple similarly high-affinity ligands soaked into microcrystals simultaneously. This extends to libraries of printed ligands dispensed directly onto TEM grids and later soaked with papain microcrystal slurries. ED-MS identifies papain binding to its preferred natural products, by showing that two analogues of E-64 outcompete others in binding to papain crystals, and by detecting papain bound to E-64 and an analogue from crude biosynthetic reactions, without purification. This illustrates the utility of ED-MS for natural product ligand discovery and for structure-based screening of small molecule binders to macromolecular targets.

biophysics↗

A non-catalytic role for MLL2 in controlling chromatin organisation and mobility during the priming of pluripotent cells for differentiation

How the chromatin regulator MLL2 (KMT2B) influences cell differentiation remains poorly understood. MLL2 is the main histone 3 lysine 4 (H3K4) trimethyltransferase acting at bivalent promoters in embryonic stem cells (ESCs) and is required for ESCs to differentiate into neuroectoderm. We show here that this requirement occurs during exit from naive pluripotency, days before neuroectoderm differentiation is impaired. Although MLL2 knockout has only a subtle effect on transcription during exit, reducing the expression of a few important neuroectodermal transcription factors, it substantially remodels chromatin architecture, disrupting 3D chromatin loops associated with bivalent promoters. The enzymatic activity of MLL2 is not needed for stabilising these loops or for neuroectoderm differentiation. This non-catalytic function of MLL2 in stabilising 3D chromatin loops has implications for lineage specification. Because MLL2 shares features with all four MLLs, chromatin tethering, rather than H3K4 methylation, may represent the primary function of MLL proteins during lineage commitment.

cell biology↗

Ambient temperature structural studies of Penicillin-binding Protein 2a of Methicillin-Resistant Staphylococcus aureus with XFELs and synchrotrons

Penicillin-binding protein 2a (PBP2a) is a transpeptidase responsible for the {beta}-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA), posing significant challenges to antibiotic therapy. PBP2as unique structural features, including its highly flexible active site and allosteric regulation, enable it to maintain catalytic activity even in the presence of {beta}-lactam antibiotics. Despite extensive characterization using cryogenic crystallography, key questions remain about its dynamic properties and conformational changes under near-physiological conditions. Room-temperature crystallography methods, particularly serial femtosecond X-ray crystallography (SFX) at XFELs, provide a powerful approach to capture these dynamics. Unlike cryogenic conditions that can constrain protein flexibility, SFX enables the study of conformational variability and interaction networks closer to physiological states. Here, we present the first room-temperature structures of PBP2a obtained using SFX to uncover insights into the enzymes flexibility, allosteric communication, and catalytic mechanisms. These findings are built upon optimized large-scale production and crystallization protocols for PBP2a, ensuring high-quality microcrystals suitable for SFX data collection. The room-temperature structures reveal novel interaction patterns, including unique salt bridge networks and dynamic structural elements absent in cryogenic studies. Furthermore, comparative analyses highlight how environmental conditions influence the conformational states of PBP2a, providing new perspectives on its resistance mechanisms. By integrating structural data from EuXFEL and LCLS, this study not only enhances our understanding of PBP2as functional dynamics but also underscores the value of room-temperature crystallography in studying antibiotic resistance. These insights could guide the design of next-generation {beta}-lactam antibiotics capable of overcoming PBP2a-mediated resistance.

biochemistry↗

Cross-Species Biomechanical Determinants of Shape Diversity

How complex molecular mechanisms translate into diverse multicellular shapes remains unclear. By leveraging the bi-layered architecture of six cnidarian species that diverged 500 million years ago, we show that modularity in supracellular mechanics governs larval shape diversity. Using active surface theory, quantitative imaging, and an inducible genetic system, we identify species-specific variations in three biomechanical modules. Basally aligned stress fibers drive axial elongation, while oral geometry and aboral rigidity define shape polarity. Remarkably, manipulating these modules transforms one species shape into another, demonstrating the causal relationship between module variation and shape diversity. Our analysis also uncovers instances of mechanical redundancies, where distinct module combinations generate similar shapes. These findings provide a general framework for how molecular complexity funnels into mesoscale mechanical determinants shaping morphological diversity.

developmental biology↗

Evaluation of Immunopharmacological Efficacy of Live Leishmania donovani Overexpressing Ld_ζ1domain for Protection Against Experimental Human Visceral Leishmaniasis

ObjectiveTo evaluate the efficacy and immunogenicity of the zeta domain over-expressing Leishmania donovani (Ld_{zeta}1domain) as a vaccination candidate against visceral leishmaniasis (VL). MethodsIn this study, Leishmania overexpressor Ld_{zeta}1domain (OE) were transformed by electroporation using a GFP-tagged Ld_{zeta}1domain recombinant plasmid. The resulting overexpressing cells were analysed in vitro to assess their growth dynamics and infectivity. We also investigated the immune-protective potential of these overexpressor in a mouse model challenged with Leishmania donovani. The immune response, including Th1 and Th2 pathways, was thoroughly characterized using RT-PCR and ELISA assays. In addition, the study conducted a thorough evaluation of the mouses spleen and liver parasites, as well as quantitative evaluation of tissue pathological changes. ResultsLd_{zeta}1 domain (OE) parasites exhibited significantly lower viability and replication rates than WT parasites, and in vivo studies showed that mice immunized with the Ld_{zeta}1(OE) domain had lower parasite numbers than mice infected with LdWT. Spleen and liver showed significant histological changes suggestive of protection. Parasite burden in the spleen and liver of vaccinated mice were significantly reduced. The immune response showed increased IFN-{gamma} levels and lower IL-10 production, resulting in a greater IFN-{gamma}/IL-10 ratio, indicating parasite elimination. The vaccination also caused a significant IgG humoral response and increased nitric oxide production in immunized mice. ConclusionOur findings demonstrated that overexpressing the zeta toxin resulted in controlled parasite attenuation, lowering pathogenicity while retaining immunogenic features. Our work established the zeta over-expressors protective efficacy, immunogenicity, and proliferation in response to a Leishmania challenge in vitro and in vivo. This preliminary prototype study suggested that Ld_{zeta}1domain (OE) parasites may be suitable for developing an attenuated vaccine against leishmaniasis. Graphical representation O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/630021v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@32dfc0org.highwire.dtl.DTLVardef@1ffe89dorg.highwire.dtl.DTLVardef@d9feorg.highwire.dtl.DTLVardef@1e7bae7_HPS_FORMAT_FIGEXP M_FIG C_FIG A schematic representation on the protective effectiveness, immunogenicity, and proliferation of the zeta over-expressor in response to Leishmania challenge in vitro and in vivo model.

pathology↗

Unveiling theranostic potential: Insights into cell-free microRNA-protein interactions

MicroRNAs (miRNAs) belong to a short endogenous class of non-coding RNAs which have been well studied for their crucial role in regulating cellular homeostasis. Their role in modulation of diverse biological pathways by intracellular or extracellular communication and interaction with DNA, RNA or protein, projects them or their targets as promising biomarkers and therapeutic agents. However, studying specific interactions in the extracellular or cell-free environment for drug discovery or biomarker establishment is resource-intensive. In this study, we derive a computational approach based on available experimental data to decipher patterns in miRNA-protein interactions in the cell-free milieu. We characterized the miRNA-protein interactome (miRPin, https://www.mirna.in/miRPin) and identified consensus sequences governing these interactions. The study establishes the role of multiple miRNAs and protein interactions present in cell-free environments leading to pathological conditions, viz., role of proteins like METTL3 and AGO2 etc. and miRNAs like hsa-miR-484 and hsa-miR-30 families, hsa-mir-126-5p etc. in association with multiple miRNAs in different cancer types, cardiovascular diseases, and neurological disorders. The findings outlined in the study may facilitate new avenues of therapeutic discovery leading to the understanding of cellular mechanisms underlying therapy relapse and drug resistance. By addressing these interactions in an extracellular environment may further gain insight into regulating disease initiation and progression, overcoming challenges related to drug efficacy and drug delivery in the presence of bilayer membranes with drug efflux pumps.

bioinformatics↗

Evaporation and pathogenesis of levitated bacteria-laden surrogate respiratory fluid droplets: At different relative humidity and evaporation stages

HypothesisAerosols are the principal cause of airborne infections and respiratory diseases. Droplets ejected from the host can evaporate and form a precipitate in the air (aerosol mode), or evaporate for some time, and fall on the ground (mixed mode) or directly fall on the ground and evaporate as sessile mode. Different evaporation modes, stages of evaporation and the relative humidity (RH) conditions affect the survival and infectivity of the bacteria in the precipitate. ExperimentsWe have investigated three droplet diameter reduction ratio-based stages of evaporation of a bacteria-laden levitated droplet at two different RH settings and evaporation modes (aerosol and mixed) mimicking real-life scenarios. The low RH condition mimics evaporation in arid regions. e.g., Delhi and the high RH conditions imitate cold areas like London. The study analyses the mass transport, micro-characterizes the samples, and investigates the survival and infectivity of bacteria in the sample. FindingsThe bacteria survive more in the high RH condition than in the low RH condition for all diameter reduction ratio-based stages and modes of evaporation. For the aerosol mode, at a fixed RH condition, the evaporation time plays a vital role as the bacteria in early-stage partially dried samples are more viable than the full precipitate. The evaporation rate, and the generation of reactive oxygen species (ROS) cause a remarkable difference in the viability and infectivity of the bacterial samples. Therefore, our findings report that the evaporation history of an infected droplet is an indispensable factor in determining bacterial viability and subsequent infectivity.

microbiology↗

Combining the CRISPR Activation and Interference Capabilities Using dCas9 and G-Quadruplex Structures

We demonstrate that both CRISPR interference and CRISPR activation can be achieved at RNA and protein levels by targeting the vicinity of a putative G-quadruplex forming sequence (PQS) in the c-Myc promoter with nuclease-dead Cas9 (dCas9). The achieved suppression and activation in Burkitts Lymphoma cell line and in in vitro studies are at or beyond those reported with alternative approaches. When the template strand (contains the PQS) was targeted with CRISPR-dCas9, the G-quadruplex was destabilized and c-Myc mRNA and protein levels increased by 2.1-fold and 1.6-fold, respectively, compared to controls in the absence of CRISPR-dCas9. Targeting individual sites in the non-template strand with CRISPR-dCas9 reduced both the c-Myc mRNA and protein levels (by 1.8-fold and 2.5-fold, respectively), while targeting two sites simultaneously further suppressed both the mRNA (by 3.6-fold) and protein (by 9.8-fold) levels. These were consistent with cell viability assays when single or dual sites in the non-template strand were targeted (1.7-fold and 4.7-fold reduction in viability, respectively). We also report extensive in vitro biophysical studies which are in quantitative agreement with these cellular studies and provide important mechanistic details about how the transcription is modulated via the interactions of RNA polymerase, CRISPR-dCas9, and the G-quadruplex.

molecular biology↗

Spatial Transcriptomics Reveals Inflammation and Trans-differentiation States of Acute Myeloid Leukemia in Extramedullary and Medullary Tissues

Acute myeloid leukemia (AML) is a heterogeneous disease of the bone marrow (medullary) but can also involve extramedullary tissues. While single cell dynamics of AML in suspension are previously explored, a comprehensive spatial transcriptomic assessment in AML remain underexplored. Here, we used Visium spatial transcriptomics to resolve medullary and extramedullary AML environments. We reveal spatial co-localization of monocytes and granulocyte-monocyte progenitors with leukemic populations in the bone marrow, sharing molecular signatures with extramedullary sites. Cell-cell communication via the CXCL12- CXCR4 axis correlated with PI3K/AKT/mTOR signaling in high inflammatory niches. Trans- differentiation states were concentrated in AML-infiltrated regions, with committed-like AML populations present in inflammatory niches and away from the trabeculae, while primitive-like AML cells localized near the endosteal niche. We validated these findings in GeoMx-based Digital Spatial profiling (DSP). Our study applied multimodal spatial transcriptomic approaches to characterize the spatial hierarchy and microenvironmental dynamics of AML differentiation states. We also demonstrated the feasibility of applying Visium-based spatial transcriptomics in decalcified bone tissues.

cancer biology↗

Blended Length Genome Sequencing (blend-seq): Combining Short Reads with Low-Coverage Long Reads to Maximize Variant Discovery

We introduce blend-seq, a workflow for combining data from traditional short-read sequencing pipelines with low-coverage long reads, to improve variant discovery for single samples without the full cost of high-coverage long reads. We demonstrate that with only 4x long-read coverage augmenting 30x short reads, we can improve SNP discovery across the genome, exceeding performance beyond even high-coverage short reads (60x). For genotype-agnostic discovery of structural variants, we see a threefold improvement in recall while maintaining precision by using the low-coverage long reads on their own, and show how we can improve genotyping accuracy by adding in the short-read data. In addition, we demonstrate how the long reads can better phase these variants, incorporating long-context information in the genome to substantially outperform phasing with short reads alone. Our experiments highlight the complementary nature of short- and long-read technologies: the former contributing higher depth for genotyping and the latter better resolution of larger events or those in difficult regions.

genomics↗