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Singh, A.

Publications and source records attributed to Singh, A..

At least 73 records · Page 4Linked to original sources

Scalable multimodal mapping of macrophage regulatory architecture by integrating optical and transcriptomic pooled screens

Understanding how genetic perturbations reshape cellular states requires measuring diverse phenotypic modalities at scale. Here, we present PerturbPair, a platform that combines parallel Perturb-Seq and optical pooled screening (OPS) in primary mouse bone marrow-derived macrophages stimulated with lipopolysaccharide. Profiling over 334,000 single-cell transcriptomes across [~]1,000 gene perturbations and 7.8 million imaging-phenotyped cells across [~]3,000 gene perturbations, we reveal high concordance between transcriptomic and optical perturbation signatures. While RNA and imaging phenotypes were broadly concordant, OPS demonstrated superior sensitivity for weak-effect perturbations owing to greater cell throughput, and captured post-transcriptional regulatory events--such as protein trapping and mTOR-dependent phosphorylation--that left no detectable transcriptional footprint. To exploit cross-modal relationships, we developed EB-MoCAVI, an empirical Bayesian variational inference framework that both imputes RNA profiles for perturbations measured only by imaging--effectively tripling our Perturb-Seq dataset in silico--and denoises transcriptomic estimates for perturbations with sparse cell coverage by leveraging matched imaging data as a regularizer. A secondary screen validated the imputed transcriptional profiles and corroborated the cytosolic iron-sulfur assembly pathway as a candidate restraint on macrophage interferon tone. Integrating measured and imputed profiles with rare-variant burden statistics from the UK Biobank identified disease-specific macrophage gene programs and causal regulatory nodes for monocyte counts, type 2 diabetes, and inflammatory bowel disease. PerturbPair establishes a generalizable framework for multimodal perturbation atlases, pointing toward quantitative, causally-informed cross-modal models of cellular behavior.

genomics↗

DMPKformer: An Interpretable Multimodal Deep Learning Framework for Reliable ADMET Property Prediction

Accurate prediction of absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties remains a critical challenge in drug discovery. Traditional single modality approaches often fail to capture the complex, multi-scale relationships governing molecular behavior across physicochemical, structural, and pharmacokinetic dimensions. In this work, we propose a multi-modal deep learning framework that integrates complementary molecular representations, MACCS fingerprints, molecular graphs, and physicochemical descriptors to achieve robust ADMET property prediction. Each modality is modeled using a specialized neural subnetwork tailored to its structural characteristics: a self-attention-based Transformer encoder for MACCS fingerprints, a Graph Attention Network (GAT) for molecular graph representations, and a tanh-activated multilayer perceptron for RDKit-, PaDEL-, and Mordred-derived descriptors. Each modality is independently trained for binary classification, and latent embeddings extracted from internal layers serve as transferable molecular representations. These embeddings are subsequently fused and fine-tuned via a tanh-activated dense network and shared prediction head to form a unified ADMET predictor. The proposed framework achieves competitive performance across multiple TDC ADMET benchmarks while providing enhanced interpretability through modality-specific attention mechanisms. In addition, the incorporation of latent-space out-of-distribution (OOD) confidence estimation enables identification of high-confidence operating regions, improving the reliability and practical applicability of the framework for molecular property prediction in drug discovery workflows.

bioinformatics↗

Biofunctional 2D Graphitic Carbon Nitride-Hydrogel Heterointerfaces for Electrochemical Detection of Interleukin-6 toward Septic Cardiomyopathy Diagnostics in Clinical Biofluids

Interleukin-6 (IL-6) is a key pro-inflammatory cytokine closely associated with sepsis progression and septic cardiomyopathy (SCM), a severe clinical condition characterized by acute cardiac dysfunction and high mortality in critically ill patients. Rapid and sensitive monitoring of IL-6 in clinical biofluids is therefore crucial for early diagnosis, disease prognosis, and timely therapeutic intervention in emergency healthcare settings. Herein, we report a biofunctional, label-free electrochemical aptasensor based on a graphitic carbon nitride-incorporated chitosan hydrogel-modified gold screen-printed electrode (MCH/Apt-IL-6/g-C3N4@CS/Au-SPE) for ultrasensitive detection of IL-6 in clinical biofluids. The electroactive g-C3N4@CS hydrogel heterointerface was engineered via electrostatic interactions between the negatively charged surface functionalities of two-dimensional graphitic carbon nitride (g-C3N4) and the protonated amino groups (-NH3+) of chitosan (CS), yielding a porous, conductive, and biocompatible sensing matrix with enhanced aptamer immobilization and accelerated electron-transfer kinetics. Biocompatibility evaluation using MTT assay and confocal fluorescence imaging demonstrated that the hydrogel maintained excellent cellular compatibility at 5 mg/mL, preserving normal cytoskeletal organization, mitochondrial integrity, and nuclear morphology, while higher concentrations induced cellular stress responses. Under optimized experimental conditions, the developed aptasensor exhibited outstanding analytical performance with an ultrawide linear detection range from 1 fg/mL to 10 ng/mL, a high sensitivity of 2.162 A/[log10(ng/mL)] cm-2, a low detection limit of 0.460 pg/mL, and excellent linearity (R2 = 0.979). In addition, the sensor demonstrated remarkable selectivity toward common biological interferents, including ascorbic acid, cysteine, glucose, glycine, and urea, together with excellent reproducibility (RSD = 1.139%). Validation studies performed in spiked human serum samples further confirmed the reliability and practical applicability of the proposed sensing platform for rapid clinical analysis. Owing to its label-free detection strategy, disposable electrode format, high sensitivity, and favorable biocompatibility, the developed g-C3N4-hydrogel heterointerface-based aptasensor represents a promising next-generation platform for early septic cardiomyopathy diagnostics, inflammatory biomarker monitoring, and point-of-care electrochemical biosensing applications.

bioengineering↗

An autoinhibitory regulatory switch governs heterotypic phase separation and liquid-to-solid phase transition of TDP-43 and tau into cytotoxic amyloids

Biomolecular condensates formed via macromolecular phase separation of proteins and nucleic acids control a myriad of essential cellular processes, whereas abnormal phase transitions into solid-like aggregates are associated with a range of fatal neurodegenerative diseases. Here, we present a unique case to demonstrate that two neuronal proteins, TDP-43 and tau, undergo heterotypic phase separation via domain-specific interactions regulated by an autoinhibitory conformational switch. Using single-molecule FRET (Forster resonance energy transfer), in combination with multi-color high-resolution imaging, fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, single-droplet fluorescence anisotropy imaging, homoFRET microscopy, fluorescence lifetime-FRET imaging, vibrational Raman spectroscopy, and electron microscopy, we unmask the interplay of molecular drivers and dissect the sequence of events associated with the formation of TDP-43:tau co-condensates that undergo liquid-to-solid phase transitions into cytotoxic amyloids. Our cellular studies show that a disease-associated cytosolic fragment of TDP-43 recruits tau into oxidative stress-induced cytoplasmic granules, eliciting cellular toxicity. Our findings provide mechanistic underpinnings of co-condensation-mediated aberrant phase transitions associated with exacerbated neuropathological outcomes.

biophysics↗

Lipogenesis-driven EGFR palmitoylation enables metastatic immune evasion in triple-negative breast cancer.

Metastasis is the leading cause of death in triple-negative breast cancer (TNBC), yet how tumor cells evade immune recognition during dissemination remain unclear. Here, we show that de novo lipogenesis drives metastatic immune evasion through FASN-mediated palmitoylation of EGFR. This modification establishes a lipid-dependent membrane signaling scaffold that sustains PI3K-AKT-mTOR signaling independently of MAPK compensation, thereby suppressing MHC-I antigen presentation through post-translational regulation. As a result, metastatic-competent cells escape CD8+ T cell surveillance and colonize distant organs. Genetic or pharmacologic inhibition of fatty acid synthase (FASN), or expression of palmitoylation-deficient EGFR mutants restores MHC-I surface expression, unleashes robust CD8 T cell activation, and markedly impairs lung metastasis without affecting primary tumor growth. This lipid-dependent EGFR-PI3K-mTOR axis operates independently of MAPK signaling and is not rescued by exogenous lipids, revealing a non-redundant metabolic dependency. Our results identify FASN-driven EGFR palmitoylation as a tumor-intrinsic immunometabolic checkpoint that couples lipid metabolism to antigen-presentation and metastatic competence. Targeting this pathway with clinically advancing FASN inhibitors offers a promising strategy to suppress metastasis by restoring anti-tumor immunity in TNBC.

cancer biology↗

SCALLOPS: a scalable, integrated computational framework for Optical Pooled Screens

Optical pooled screens (OPS) link pooled genetic perturbations to high-dimensional image-based phenotypes at scale, but their widespread adoption is hindered by computational bottlenecks in processing terabyte-scale, multimodal image data. We present SCALLOPS, a unified, modular, and cloud-native computational framework that overcomes these bottlenecks. SCALLOPS implements a "well-centric" processing strategy that integrates robust stitching with a non-linear two-stage registration strategy, enabling accurate alignment of multi-magnification images, reliable single-cell genotype-phenotype linkage, and efficient morphological feature extraction. Benchmarking with public and newly-generated datasets demonstrated SCALLOPS superior performance over existing solutions. Crucially, SCALLOPS uniquely enables robust processing of 4x magnification in situ sequencing data, accelerating image acquisition by around six-fold. We applied SCALLOPS to an optical pooled screen investigating the estrogen receptor (ER) degrader vepdegestrant in a breast cancer cell line, successfully recovering its known mechanism of action, highlighting the value of OPS in translational research. SCALLOPS provides a scalable end-to-end solution, making large-scale OPS routine.

bioinformatics↗

DigitAb: Domain-Adaptive Cell Type Prediction Method from Light Microscopy Images

Light microscopy imaging with histological stains is central to disease diagnosis and research. It is enhanced with immunostaining to reveal cellular composition and complexity linked to clinical utility and biological mechanisms. Emerging multiplex imaging technologies like Phenocycler markedly increase the coverage to capture the cellular diversity but are costly, technically demanding, and inaccessible to most clinical laboratories. We developed DigitAb, a deep learning framework that classifies cell types directly from hematoxylin and eosin (H&E) stained slides, eliminating the need for specialized assays. Using Phenocycler imaging, we generated highlZlresolution ground truths for [~]3.5 million cells from 29 human kidney samples across four multi-institutional datasets to train a semantic segmentation model for 10 cell types, achieving a balanced accuracy of 0.78. By employing an integrated adversarial domain adaptation module, we tested DigitAb on unlabeled and untested biopsy samples from kidney transplant and diabetic samples. We were able to predict several cell types just from histology images, without using any special technology or immunostains, and demonstrate high concordance with clinical gold-standard Banff schema in kidney transplant rejection, and clinical characteristics of diabetic nephropathy. Our cloudlZlbased tool, DigitAb, provides scalable, accessible, labellZlfree cellular segmentation for research and clinical pathology.

pathology↗

Computational drug repurposing identified Artemisinin and Mebendazole as potential inhibitors of virulence-associated proteins SKSR and essential kinases CpCDPK1 of Cryptosporidium parvum

Cryptosporidium parvum is a protozoan parasite responsible for cryptosporidiosis, significantly threatening immunocompromised individuals, particularly HIV/AIDS patients, by causing severe diarrhea and potential mortality. Current treatments are largely ineffective, prompting investigations into new therapeutic options. This study evaluated two antiparasitic drugs: Mebendazole, used for helminth infections, and Artemisinin, used for malaria. The SKSR gene family encodes virulence factors in C. parvum, and Calcium-dependent protein kinase1 (CpCDPK1) regulates the life cycle of C. parvum; targeting these proteins may reduce growth and infection in hosts. In the current study, molecular docking was conducted taking Mebendazole and Artemisinin drugs as ligands, SKSR gene family and CpCDPK1 proteins as drug targets. Results with SKSR showed binding energy of -4.9 kcal/mol, -6.72 kcal/mol for Mebendazole and Artemisinin, respectively. Whereas, with CpCDPK1, the binding energies were -6.44 kcal/mol, -9.18 kcal/mol for Mebendazole and Artemisinin, respectively. Docking of Nitazoxanide (an in-use drug for C. parvum) with SKSR and CpCDPK1 revealed binding energies -4.2 kcal/mol, -4.81 kcal/mol, respectively. The stability of the proteins (targets) upon binding to the ligands was assessed by performing all-atom MD simulations for 100ns using the GROMACS package. No major variations were observed upon binding of Artemisinin and Mebendazole to SKSR and CpCDPK1. The findings of MD simulations imply that both proteins maintain their stability upon binding of Artemisinin and Mebendazole. Molecular Docking and MD simulation studies suggest that Artemisinin and Mebendazole are potential candidates for repurposing in the treatment of C. parvum infections, with recommendations for in vitro studies to validate these findings.

molecular biology↗

Repurposing antiviral drugs as a new avenue for Klebsiella pneumoniae decolonization

Klebsiella pneumoniae (Kp) is a common antibiotic-resistant pathogen that colonizes the gastrointestinal tract and can disseminate to peripheral sites, causing a range of infections including bacteremia, urinary tract infections, and pneumonia. Intestinal colonization with Kp is a risk factor for subsequent infection, as the colonizing strain frequently corresponds to the infecting isolate. Accordingly, targeting Kp prior to dissemination at the site of colonization through decolonization strategies offers a promising approach to mitigate infection risk. In this study, we evaluated the repurposing of existing drugs with previously uncharacterized antibacterial activity as candidates for Kp decolonization. To this end, we screened an antiviral compound library for their activity against Kp. We identified and validated six compounds with previously uncharacterized activity against Kp. Then, we screened a library of clinical Kp strains against a subset of these compounds and found that their activity was strain-specific to degrees that differed based on the compound. Finally, we tested the activity of these compounds in conditions relevant to the human gut. We determined the activity of these candidates was dependent on biological context. Collectively, these findings support further investigation of antiviral drugs as potential gut decolonization therapies for Kp.

microbiology↗

The role of cell growth rate on accumulation of the mitotic cyclin Cdc13 in fission yeast

Eukaryotic cells control their size by coordinating growth and division. Fission yeast divide at a reproducible cell size due to regulated activation of the cyclin-dependent kinase Cdk1. The nuclear concentration of mitotic cyclin Cdc13 increases in a time-dependent manner to promote Cdk1 activation as cells grow. Here, we show that interphase Cdc13 is stable against degradation and nuclear export, but is diluted by cell growth. Low glucose reduced cell growth rate but not time-dependent accumulation of Cdc13. Uncoupling the rates of cell growth and Cdc13 accumulation resulted in higher concentrations of nuclear Cdc13 despite reduced cell size. This change coincided with reduced activating phosphorylation of Cdk1-T167. Mathematical modeling and experiments showed that cells maintain size homeostasis under these conditions. In contrast to low glucose, poor nitrogen reduced both cell growth rate and Cdc13 accumulation rate. Therefore, Cdc13 accumulation is independent of cell growth rate but can be altered by nutrient-specific mechanisms.

cell biology↗

Dual-compartment engagement of STAR-family proteins SAM68 and QKI by LINC00941 sustains oncogenic fitness in RAS-driven lung cancer

Long non-coding RNAs (lncRNAs) are increasingly recognised as effectors of oncogenic signalling, yet the transcriptional programmes through which driver mutations regulate lncRNA expression remain poorly defined. Here we identify LINC00941 as a direct transcriptional target of FOSL1, an AP-1 transcription factor downstream of the KRAS-MAPK pathway, establishing the first FOSL1-regulated lncRNA in lung adenocarcinoma (LUAD). LINC00941 is significantly upregulated in LUAD across multiple independent cohorts, and its depletion via siRNAs, shRNAs, and antisense oligonucleotides (ASOs) induces proliferative arrest and stress-induced premature senescence, accompanied by transcriptomic suppression of cell cycle and DNA damage response (DDR) genes. Mechanistically, LINC00941 operates through a dual-compartment mechanism engaging two STAR-family RNA-binding proteins in distinct subcellular contexts. In the nucleus, LINC00941 binds SAM68 through its 700-1300 nucleotide region and shields it from proteasomemediated degradation, thereby sustaining SAM68-dependent PARP1 activation and DDR competency; RNF123 is identified as a candidate E3 ligase mediating SAM68 turnover in the absence of LINC00941. In the cytoplasm, LINC00941 sequesters QKI, preventing its nuclear translocation; LINC00941 depletion releases QKI to the nucleus, driving alternative splicing dysregulation including validated NUMB exon 12 exclusion, and QKI co-depletion rescues the anti-proliferative phenotype both in vitro and in xenograft models. Multi-cohort survival analysis across three independent LUAD datasets (n=649) identifies LINC00941 as an independent prognostic factor for poor overall survival. Gymnotic ASO-mediated targeting of LINC00941 significantly suppresses xenograft tumour growth without systemic toxicity, providing preclinical proof-of-concept for therapeutic tractability. Together, these findings establish LINC00941 as a compartment-specific oncogenic scaffold within the KRAS-FOSL1 transcriptional axis and a tractable therapeutic target in LUAD.

cancer biology↗

Sex-specific weighting of shoal size and movement speed but no evidence of asymmetric dominance effect in zebrafish shoal-size preference

Social decisions often require animals to integrate information across multiple attributes of potential partners. Using biological motion stimuli, point-displays generated from tracked live shoals, we tested how adult zebrafish (Danio rerio) weigh shoal size and movement speed during social preference, and whether these preferences are susceptible to contextual manipulation by an asymmetrically placed alternative. In Experiment 1, we established a multi-attribute indifference point by presenting males and females with dichotomous contrasts in which shoal size and movement speed were traded off. Both sexes showed no preference when a larger, slower shoal (4 fish at 0.75x speed) was pitted against a smaller, faster shoal (2 fish at 1.25x speed), but preferred the smaller, faster shoal when the speed difference was greater (4 fish at 0.5x versus 2 fish at 1.25x), indicating that zebrafish are sensitive to graded differences in movement speed relative to numerical cues. In Experiment 2, unidimensional tests confirmed that both sexes preferred larger shoals when speed was held constant but revealed sex-based differences in speed sensitivity: males preferred faster-moving shoals at both shoal sizes tested, whereas females showed no significant speed preference. Male shoal size preferences were stronger at higher movement speeds, suggesting that speed modulates the strength of size preference. In Experiment 3, we tested the asymmetric dominance effect in males, the only sex sensitive to both dimensions, using the indifferent contrast from Experiment 1 as the primary options and four decoy shoals asymmetrically placed along either the size or speed dimension, under counterbalanced presentation orders. No decoy shifted male preference significantly from chance under any condition. These results indicate that zebrafish weigh social cues in a sex-specific manner, and that asymmetric decoy options do not induce preference biases in males when shoals vary along the dimensions of movement speed and size.

animal behavior and cognition↗

Synthetic Biomolecular Condensates as Tunable Microtubule Assembly Hubs

Phase separation of proteins and nucleic acids (NAs) into nano-to-microscale condensates can regulate biochemical processes, including assembly and organization of cytoskeletal networks such as actin and microtubules. This study examines the functional role of condensate material properties in microtubule assembly. Learning from the sequence grammar of naturally occurring intrinsically disordered regions in microtubule-associated proteins, two-component peptide-NA condensates with programmable material properties were designed. These synthetic condensates catalyze tubulin polymerization into microtubule filaments with tunable outcomes. Tubulin preferentially partitions to the condensate interface and nucleates microtubule assembly. Enhanced tubulin self-assembly produces long filaments that exhibit branching and bundling. Using a minimal stochastic chemo-mechanical model, we show that sequence-encoded condensate viscoelasticity is a tunable element that controls filament morphologies and identifies interfacial rheology as the key regulator of filament growth. Fluorescence recovery after photobleaching experiments support this model, revealing a direct correlation between interfacial tubulin mobility and condensate-directed microtubule assembly. Distinct regimes emerge due to competition between bulk adsorption and lateral diffusion of tubulin at the condensate interface, which determines whether filament tips grow or stall. Since dynamic microtubule assembly and restructuring are essential for various cellular functions, this work highlights a critical role of condensate interfacial rheology in cytoskeletal organization.

biophysics↗

KCa3.1 Drives Pro-Fibrotic Activation and Represents a Novel Therapeutic Target in Aortic Stenosis

IntroductionAortic stenosis (AS) is characterised by progressive aortic valve (AV) leaflet fibrosis and calcification, yet no medical therapies exist to slow disease progression. AV interstitial cells (VICs) that differentiate into myofibroblasts are central drivers of fibrosis. The Ca2+-activated K+ channel KCa3.1 promotes pro-fibrotic signalling in several fibrotic diseases, however its role in AS remains unknown. MethodsKCa3.1 protein expression was examined in paraffin embedded tissue by Immunohistochemistry from control and AS valve tissue. VICs were isolated, cultured and phenotypically characterised as myofibroblasts from AV tissue obtained from patients with severe tricuspid AS undergoing surgical AV replacement (n=19). KCa3.1 mRNA and protein expression were assessed by qRT-PCR and immunohistochemistry, and functional channel activity confirmed using patch-clamp electrophysiology. The effects of transforming growth factor-{beta}1 (TGF{beta}1) stimulation and pharmacological inhibition with the selective KCa3.1 blocker senicapoc were examined. ResultsImmunoreactive KCa3.1 channels and smooth muscle actin were detected in both control and AS aortic valve tissue, localised to elongated, nucleated interstitial cells, with significantly higher expression observed in AS tissue compared to control. Isolated VICs exhibited an activated myofibroblast phenotype, expressing THY-1, vimentin, collagen and -smooth muscle actin (SMA) (n=9). Myofibroblasts expressed KCa3.1 mRNA and protein and demonstrated functional plasma membrane channels. TGF{beta}1 stimulation increased KCa3.1, SMA and collagen type I mRNA expression, while KCa3.1 blockade with senicapoc (100 nM) significantly attenuated TGF{beta}1-induced SMA expression, stress fibre formation and collagen gel contraction. Senicapoc had no effect on myofibroblast proliferation or migration. ConclusionsWe show for the first time that functional KCa3.1 channels are expressed in human AS tissue and AV myofibroblasts, where they regulate myofibroblast contraction, -SMA expression, and differentiation, promoting pro-fibrotic activity. These responses are attenuated by the selective KCa3.1 inhibitor senicapoc. Given its established safety in phase 3 clinical trials, KCa3.1 inhibition represents a promising and readily translatable anti-fibrotic therapeutic strategy for AS.

cell biology↗

Premotor cortex uses a compositional neural geometry to plan words

Speech requires precise serial ordering of words and phonemes into novel combinations. To accomplish this, the brain is believed to flexibly prepare utterances before producing them, even allowing pronunciation of never-before spoken words. To discover how neural populations achieve this, intracortical activity from premotor cortex was recorded while two speech neuroprosthesis pilot clinical trial participants attempted to speak factorially-balanced phoneme sequences. During preparation, activity encoded not only the next-phoneme, but multiple upcoming phoneme positions spanning whole words. We found that word-level plans were formed by compositionally combining phoneme representations, a mechanism that may enable efficient planning of novel sequences. When utterances contained more than one word, premotor cortex activity was largely limited to the first word, suggesting that articulatory planning is segmented by higher-order features. Together, these results reveal a compositional, hierarchically-segemented planning geometry, potentially a universal neural strategy for sequence organization across higher levels of language.

neuroscience↗

Engineered 3D hydrogel model reveals divergence of adhesion-migration balance in Glioblastoma under simulated microgravity

Glioblastoma is an aggressive brain cancer whose cells can switch between different modes of invasion in response to their surroundings, making the disease difficult to predict and treat. How physical forces influence this adaptability remains poorly understood. Here, we used simulated microgravity together with engineered hydrogels that independently control adhesion, degradability, and mechanical properties to test how gravity affects glioblastoma invasion. Microgravity strongly reduced invasion and shifted cells from elongated, protrusive behavior to a more cohesive state. Proteomic analysis showed reduced invasive signaling together with increased cell-matrix and cell-cell adhesion, consistent with a redistribution of contractile forces toward the cell edge. Under normal gravity, blocking CD44, integrin {beta}1, or N-cadherin reduced matrix-dependent invasion. In contrast, under microgravity, inhibiting these same adhesion pathways restored invasion, indicating that microgravity traps cells in an overly adhesive, cohesive state that limits movement rather than motility itself. These findings show that gravity is an important regulator of cancer cell plasticity and reveal a mechanically induced vulnerability in glioblastoma invasion. More broadly, combining defined biomaterials with gravitational modulation provides a new way to study how physical forces shape tumor behavior.

cancer biology↗

Impact of variability in cell generation times on cell-to-cell variability of protein concentrations

The influence of arbitrary randomness in cell division times on the variability of protein copy numbers within a lineage ensemble has been recently studied, going beyond the contributions of noisy gene expression and partitioning error. However, variability of protein concentrations need separate study, since cell size growth between cell divisions dilute protein concentrations at the same rate as size growth, which also determines mean division times. Here for a model of bursty protein production, we present exact moments (of all orders) of protein concentrations in the cyclo-stationary state, comparing: (i) population and lineage cell ensembles, and (ii) statistics at different cell ages. Two interesting results emerge. While the variance of protein concentration changes with the degree of division time heterogeneity at any cell age, the age-averaged variance is independent of it within lineage ensemble but stays dependent within population ensemble. The skewness within population ensemble is higher in younger cells than within lineage ensemble, and this behavior reverses at older ages. Such a feature vanishes for the age-averaged distribution, with population based skewness always dominating over that of lineage. We also show that mother-daughter correlations in generation times, do not add any significant difference to the results.

systems biology↗

Continual Learning for Emerging Epitope Landscapes in TCR peptide Binding Prediction

The TCR-peptide binding landscape evolves continuously: novel pathogens (SARS-CoV-2, emerging influenza variants) and newly characterized tumor neoantigens introduce epitope families with no training precedent. Deploying a static model trained on historical data leads to degraded performance on emerging epitopes, while naive fine-tuning on new data causes catastrophic forgetting--erasing performance on previously learned epitopes. We introduce ContinualTCR, a continual learning framework that combines reservoir replay with Elastic Weight Consolidation (EWC) regularization to balance stability (retaining old-epitope performance) and plasticity (adapting to new epitopes). Evaluated on a temporally partitioned VDJdb- IEDB benchmark across four sequential epitope arrival tasks, ContinualTCR achieves new-epitope AUROC 0.812 and old-epitope AUROC 0.781 simultaneously--reducing catastrophic forgetting by 62.9% relative to naive fine-tuning. A streaming evaluation protocol with per-task backward transfer (BWT) reporting reveals that replay alone resolves 30.6% of forgetting, EWC alone resolves 57.3%, and their combination achieves synergistic complementarity. These results establish continual learning as a necessary component of production TCR specificity systems that must adapt to evolving pathogen and neoantigen landscapes without requiring full retraining.

bioinformatics↗