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Rai, S.

Publications and source records attributed to Rai, S..

At least 19 recordsLinked to original sources

Developmental origins of thymic B-cell lymphomas

The thymus provides a specialized niche for lymphocyte differentiation, yet the developmental trajectories of its rare B-cell population and their relationship to thymic B-cell lymphomagenesis remain poorly understood. Here, we integrate single-cell multiomics and spatial profiling across human tissues to delineate a B-cell differentiation program selectively represented in the human thymus. This program links CCL17 and germinal center-like B-cell states along a trajectory distinct from canonical germinal center differentiation and can be recapitulated in vitro by signals operating in the thymic medulla. Extending this framework across human B-cell lymphomas, we identify an inherent malignant cell state in PMBCL that shares transcriptional and epigenetic features with CCL17 thymic B cells. This malignant state associates with early clonal positions in reconstructed B-cell receptor phylogenies and persists within tumor microenvironments distinct from the thymic niche. Together, these findings support a model in which thymus-specific B-cell differentiation programs are redeployed during thymic B-cell lymphomagenesis.

cancer biology↗

Relatedness and last male sperm precedence in Cheilomenes sexmaculata: Implications for inbreeding avoidance

Avoidance to mate with relatives is a common evolutionary strategy, as it helps maintain genetic diversity and overall fitness within populations. Females often prefer unrelated males to mitigate the risks associated with inbreeding, such as the expression of deleterious recessive alleles. This preference can involve various post-copulatory mechanisms through which females bias paternity towards males with potentially better genes. The phenomenon of last male sperm precedence, where the last male to mate with a female tends to sire the majority of offspring, is well-documented in ladybird beetles. However, how relatedness affects this phenomenon remains unclear. This study aims to investigate whether paternity share is altered when the last male to mate with a female is related to her. By conducting double mating experiments with two different morphs (typical and intermediate) as phenotypic markers, we seek to determine if relatedness disrupts last male sperm precedence. It was hypothesised that females of Cheilomenes sexmaculata will prefer unrelated males over related ones, irrespective of mating order, potentially breaking down the last male sperm precedence. This preference for unrelated males was reflected in our results with unrelated males exhibiting enhanced reproductive success. Females were more fecund and exhibited higher egg viability with unrelated males. Greater paternity share was observed for unrelated males when the second male was related to the female. This study highlights the dynamic nature of sperm precedence and the role of mate quality in female mate choice, emphasizing the importance of inbreeding avoidance in sexual selection.

zoology↗

Plasma Extracellular Vesicle Lipidomics Reveals an SMPD1-Driven Sphingomyelin Salvage Pathway Collapse in Parkinson's Disease

While lysosomal lipid dysregulation is implicated in Parkinsons disease (PD), identifying the precise enzymatic drivers remains limited by the lack of subcellularly resolved metabolic mapping. Leveraging endosome-origin plasma extracellular vesicle (PsEV) lipidomics, we identified a profound bidirectional disruption of the ceramide-sphingomyelin (SM) axis in PD, driven by asymmetric upregulation of sphingomyelin phosphodiesterase 1 (SMPD1) and sphingomyelin synthase 1 (SGMS1). BODIPY-C5 SM tracking revealed that SMPD1 perturbation severely impairs lysosomal SM turnover. Crucially, this SMPD1-driven hydrolysis forces a salvage pathway collapse, bottlenecked by SPHK1/SGPL1 downregulation, which precipitates oxidative membrane damage and PINK1/Parkin-dependent mitophagy failure. We robustly validated this multi-pathway dysfunction across orthogonal in vitro, in vivo mouse, and postmortem human brain models. Furthermore, SMPD1/SGMS1 expression distinctly stratifies clinical phenotypes, marking the aggressive Postural Instability/Gait Difficulty (PIGD) subtype. Our findings establish SMPD1-mediated lysosomal impairment and ceramide-SM imbalance as a core biochemical axis in PD pathophysiology.

neuroscience↗

Single-cell spatial multi-omic characterization of the tumour microenvironment in transformed follicular lymphoma

Histological examination of follicular lymphoma (FL) biopsies remains the cornerstone for diagnostic grading of FL. Single-cell sequencing approaches, while transcriptomically rich, require tissue dissociation and lose the native spatial context that underpins FL transformation to diffuse large B-cell lymphoma (DLBCL). To investigate the spatial interplay between malignant B-cells and the tumour microenvironment (TME) across disease states, we performed subcellular single-cell spatial transcriptomics and spatial proteomics on 12 paired pre/post-transformation samples and 10 non-transforming FL controls, integrated with matched single-cell whole genome sequencing (scWGS). Our analysis reveals that transformation is accompanied by a shift toward B-cell-predominant stromal and immunosuppressive cellular neighbourhoods, where the magnitude of expansion correlates with time to transformation. Prior to transformation, immunomodulatory Galectin-9 interactions move from the intra-follicular core to the extra-follicular space. Integration with scWGS demonstrates that high copy-number instability in malignant B-cells is associated with reduced supportive T-cell niches and intensified immunoregulatory crosstalk at the transformed state. Collectively, our multi-omic analysis characterizes TME remodeling during FL transformation, contributing to a refined disease evolution model.

bioinformatics↗

Multi-scale modeling of human tissues from spatial transcriptomics with TERRA

Spatial transcriptomics maps gene expression at cellular resolution, revealing how cells organize into multicellular niches. Yet computational analyses remain dataset-specific, without a transferable representation of tissue organization that generalizes across datasets, tasks and tissues or predicts how tissues behave under perturbation. We present TERRA, a foundation model pretrained on 112 million human cells profiled by spatial transcriptomics. From a single pretrained backbone, TERRA yields embeddings at the scale of cells, the genes they express and the neighborhoods in which they reside, and supports spatial in silico perturbation, all applied zero-shot to unseen tissues. At the cell level, in newly generated spatial data for developing pancreas, TERRA identified an islet-associated capillary state which we posit represents a developmental precursor of the mature islet microvasculature. At the gene level, in untreated kidney sections, in silico knockout of immune-checkpoint targets predicted a gene program of immune-checkpoint-blockade-associated nephrotoxicity, which we validated in treatment-exposed tissue and recovered in blood. At the neighborhood level, TERRA mapped macrophages across tissues to identify recurring cross-organ niches, which we term archetypes, including a tumor-boundary niche associated with poor prognosis in kidney cancer. Together, TERRA captures the spatial and multicellular logic of human tissue and predicts, in silico, its response to perturbation, providing a multi-scale framework for tissue biology, therapeutic development and clinical application.

genomics↗

Deep Brain Stimulation Microelectrodes as a Source of Human Subcortical RNA: Validation of a Low-Input Transcriptomic Protocol

BackgroundUnderstanding the molecular basis of Parkinsons disease (PD) phenotypic heterogeneity maybe improved by in vivo access to deep brain tissue. Deep brain stimulation (DBS) surgery offers a unique opportunity: microelectrodes traversing the subthalamic nucleus (STN) carry adherent brain tissue upon withdrawal, providing a source of RNA from subcortical regions in living patients without additional invasive procedures. AimTo develop and validate a low-input RNA extraction and transcriptomic profiling protocol using DBS microelectrodes in post-mortem human brain, to confirm that recovered RNA is of brain rather than blood origin, and to characterise its sub-regional and cellular identity. MethodologyDBS microelectrodes were inserted without image guidance or guide tube into three unfixed post-mortem human brains targeting the STN trajectory. In clinical practice, a guide tube shields the electrode from cortical tissue; its absence here means tissue from the full insertion trajectory may contribute to recovered RNA. Thirty-eight microelectrodes were evaluated across single and pooled strategies. RNA was extracted using a modified RNeasy Micro low-input protocol; libraries prepared using NEBNext Single Cell/Low Input RNA Library Kit and sequenced on Illumina NovaSeq 6000 (paired-end, 2x150 bp). Tissue identity was validated against GTEx v10 (54 tissues) and Allen Human Brain Atlas (ABA, 19 subcortical regions including STN) using Pearson correlation with permutation testing (1,000 permutations) and BH-FDR correction. Transcriptional overlap between subcortical and cortical reference regions was quantified and subcortical-enriched gene filtering performed. ResultsTwenty-five RNA isolates were obtained from 38 microelectrodes; 54.5% of Bioanalyzer-assessed samples achieved RIN [&ge;]5 (median 7.1; range: 5.9-7.8). Fifteen libraries passed sequencing QC (mean depth 43.0 {+/-} 14.1 million read pairs; mean Q30 83.2 {+/-} 5.6 %). PCA of rlog transformed expression data resolved samples by donor identity. All samples confirmed brain tissue origin by GTEx {tau}-index tissue specificity correlation (n=996 brain and blood specific markers). Brain correlations were highest for frontal cortex (mean r= 0.683 {+/-} 0.072), anterior cingulate cortex (mean r= 0.658 {+/-} 0.069), amygdala (mean r= 0.615 {+/-} 0.068), and basal ganglia including caudate (mean r= 0.553 {+/-} 0.059), putamen (mean r= 0.546 {+/-} 0.059), and nucleus accumbens (mean r= 0.544 {+/-} 0.057); all BH-FDR < 0.05. Cerebellum showed the lowest brain correlations (cerebellar hemisphere: mean r = 0.327 {+/-} 0.039; cerebellum: mean r = 0.314 {+/-} 0.037). Whole blood correlation was strongly negative (mean r= -0.250 {+/-} 0.079), confirming non-haematological origin. ABA genome-wide analysis confirmed positive STN correlation (r=0.54-0.62; permutation p<0.001). MuSiC cell-type deconvolution against the Allen Brain Atlas HMBA-BG snRNA-seq reference identified oligodendrocytes (33.5 {+/-} 17.2%), frontal cortical neurons (9.1 {+/-} 7.0%), STR D1 MSNs (6.0 {+/-} 4.9%), and dopaminergic neurons (1.1{+/-} 2.7%) as the principal cell types, independently corroborating bulk transcriptomic findings at single-cell resolution. ConclusionThis study validates a low-input RNA extraction protocol for DBS microelectrodes, confirming brain-specific transcriptomic profiles consistent with STN-adjacent subcortical sampling. The 96% transcriptional overlap between cortical and subcortical regions, combined with absence of a guide tube in this post-mortem model, limits sub-regional specificity; clinical application with a guide tube would enrich the subcortical signal. These findings provide the methodological framework for in vivo molecular profiling of the human basal ganglia during DBS surgery in PD patients.

genetics↗

A Scalable Framework for Species-Resolved Human Gut Microbiome Profiling Using Full-Length 16S rRNA Sequencing

The gut microbiota plays a fundamental role in human health, nutrition, immune development, and disease, driving widespread adoption of 16S rRNA gene sequencing for microbial community characterization. Short-read V3-V4 sequencing remains the dominant approach for large-scale microbiome studies; however, interrogation of only a small fraction of the 16S gene limits phylogenetic resolution and frequently restricts biological interpretation at the species level. Although full-length (V1-V9) 16S sequencing has emerged as a promising alternative, comprehensive evaluation of highly multiplexed full-length workflows in complex human gut microbiomes remains limited. Here, we establish and evaluate a full-length 16S framework for species-resolved human gut microbiome profiling. The workflow was assessed using defined microbial communities, technical replicates, and healthy human fecal microbiomes. Full-length sequencing generated highly concordant taxonomic profiles across independent technical workflows and enabled reproducible recovery of complex microbial communities at both genus and species levels. Application to human fecal microbiomes revealed substantial inter-individual heterogeneity together with extensive ASV-level microdiversity, highlighting the ability of full-length sequencing to resolve fine-scale phylogenetic variation within dominant gut-associated taxa. To quantify the analytical gain afforded by full-length sequencing, V3-V4 datasets were computationally reconstructed directly from identical full-length reads, eliminating methodological and biological confounders. While alpha diversity metrics and overall community structure remained highly concordant between approaches, full-length sequencing markedly improved taxonomic resolution, increasing species-level assignment from approximately 20% to 98% and resolving substantial intra-genus diversity within clinically and ecologically relevant genera including Bifidobacterium, Prevotella, Blautia, Enterococcus, and Klebsiella. Collectively, these findings position full-length 16S sequencing as an enabling technology for the next generation of microbiome studies, where species-level resolution can be integrated with large-scale cohort, longitudinal, and population-health investigations.

genomics↗

Endocrinology shadows ecology: Characterization of Markhor (Capra falconeri heptneri) reproductive cycles through non-invasive hormone assessment

Markhor (Capra falconeri) is a charismatic, threatened, large, high-altitude bovid found in parts of central and south Asia. The species faces threats such as habitat loss, hunting, poaching, livestock competition, hybridisation, and disease, yet research on wild populations is challenging. Various biological aspects, including surveys, diet, population dynamics, interactions with livestock, hybridisation, and disease, have been studied locally, along with behavior and reproductive biology, but details such as pregnancy, oestrus, and parturition timing remain unestablished. We conducted the first systematic, detailed, and fine-scale characterization of the reproductive steroid profiles of two males and five female markhors (Capra falconeri heptneri) in a captive population at the Padmaja Naidu Himalayan Zoological Park (PNHZP), West Bengal, India. We collected weekly fecal samples, standardized and validated measurements of progesterone (fP4M) and testosterone (fTM) metabolites, and conducted reproductive profiling to assess reproductive stages in both sexes. Analyses of annual fP4M and fTM data from male and female markhor individuals showed similar profiles and synchronicity, with individual variation, and peaks and baselines were evident for both hormones. In both sexes, significantly higher hormone titres were observed during the sexually active and inactive phases. Non-invasive measurement of reproductive hormones accurately reflected ovarian function in females, helping establish mating, gestation, and parturition timelines in female markhors and determine the breeding season in males. These approaches support husbandry and breeding management by identifying optimal pairing, diagnosing pregnancy, and predicting parturition in both captive and wild populations. When applied correctly, these tools could greatly aid population monitoring of other endangered species across high-altitude regions worldwide.

physiology↗

MNRR1 is required for Triple Negative Breast Cancer growth and metastasis and can be targeted by repurposed drugs.

Despite progress in recent decades, breast cancers remain the most diagnosed malignancies, and second leading cause of cancer death, in women. Although improved screening and systemic and endocrine adjuvant approaches have contributed to major declines in breast cancer mortality, current standard of care drugs are extremely toxic, and many women continue to be overtreated. Although nearly two-thirds of breast cancers are hormone-responsive, aggressive subtypes, particularly Triple Negative Breast Cancer (TNBC), still lack safe oral medications. Recently the roles that mitochondria play in TNBC carcinogenesis, metastasis, and resistance to treatment have garnered a great deal of attention. Contrary to the popular dogma that cancer cells are powered by glycolysis, metastatic breast cancer cells have enhanced mitochondrial function. Our work identified that Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1; also, CHCHD2, PARK22), a key coordinator of mitochondrial-nuclear crosstalk that is physically present in both compartments, is overexpressed in TNBC cells and is an important regulator of metastasis signaling. We have identified Heat Shock Factor 1 (HSF1) as the main transcription factor that activates the MNRR1 promoter in TNBC cell lines. In the mitochondria, MNRR1 protein facilitates ATP production and inhibits apoptosis, whereas in the nucleus it regulates the transcription of stress-responsive genes including several required for epithelial to mesenchymal transition (EMT), metabolic flexibility, and cell growth. Thus, each of the bi-organellar functions of MNRR1 constitutes processes regarded as hallmarks of cancer. For reasons that are not yet fully understood, MNRR1 levels display a significant and robust ancestry bias, showing increased expression in tumor samples from Non-Hispanic Black (NHB) women when compared to disease-matched tumors from Non-Hispanic White (NHW) patients. It is possible that increased levels of MNRR1 may underlie the aggressive metastatic phenotype observed in many NHB patients. In further support of this observation, loss of MNRR1 function, either genetically or by use of inhibitors, reduces TNBC growth and metastasis. MNRR1 therefore is an attractive therapeutic target that could be exploited for design of novel therapies or as adjuncts to existing ones.

cancer biology↗

Holobiomes in succession: post-glacial microbial communities are structured by hosts, time and habitat heterogeneity

O_LIGlacier forefields in the high-desert region of Ladakh (northwestern Himalaya) are colonized by a variety of interdependent organisms, including lichens, prokaryotes, fungi, mosses, and vascular plants, along a successional gradient. Together with bulk soil, these hosts and their associated microorganisms form a broader microbial metacommunity (holobiome) whose structure, interactions and functions remain poorly underexplored in one of the Earths most extreme and climate-sensitive environments. C_LIO_LIUsing a multidisciplinary approach combining glacial chronosequence transects, GIS-derived topographic variables, soil properties, and plot cover measurements, we assessed the abiotic and biotic factors influencing bacterial and fungal communities sequenced from different hosts and bulk soil (hereafter sources). Microbial composition was primarily shaped by source identity, though certain sources, such as biological soil crusts (BSCs), mosses, and plant rhizospheres, also showed relationships with moraine age in either bacterial or fungal communities. C_LIO_LIBacterial and fungal community congruence was tested using Procrustes analyses, revealing that mosses maintained tightly coupled inter-kingdom relationships throughout the glacier forefields. However, the degree of congruence in plant rhizospheres and bulk soils was influenced by topographic variation and moraine age, respectively. C_LIO_LICo-occurrence network analyses revealed that early successional microbial communities were assembled more stochastically, with bacteria being more interconnected than fungi. In contrast, late successional stages were more compartmentalized, being more structurally stabile, likely driven by increased plant cover and functional redundancy among microbial taxa. C_LIO_LIKeystone bacterial and fungal taxa were identified in plant rhizospheres and bulk soil using a dual-criteria approach related to inter-kingdom congruence and network node eigenvalues. Furthermore, some of these taxa were associated with environmental factors, suggesting topographic heterogeneity and successional age can promote or deter the influence of keystone taxa. C_LIO_LISynthesis: This study reveals the impact of both macroorganism colonization (i.e. plants, mosses, and lichens) and microcommunity establishment (BSCs and bulk soil), as abiotic and biotic sources, on microbial metacommunity assembly in glacier forefields. By adopting a broader approach across different spatial scales, we demonstrate that while plant colonization plays a central role in shaping microbial metacommunities, its effects are modulated by topographic variation along the chronosequence. C_LI

microbiology↗

Ciliary sensing in tanycytes couples nutrient availability to metabolic regulation

Body homeostasis relies on accurate communication between the brain and the periphery. Disruption of this communication can contribute to disease. Tanycytes are located at the interface of the cerebrospinal fluid (CSF), bloodstream, and hypothalamus, where they sense circulating nutrients and regulate neuroendocrine axes and metabolism. However, the mechanisms by which they sense CSF signals remain largely unclear. Recent evidence that tanycytes possess primary cilia -- key sensory organelles -- led us to hypothesize that tanycytic cilia function as sensory antennae that detect metabolic cues in the CSF. Here, we demonstrate that tanycytic cilia exhibit distinct morphologies across subtypes and physiological states. They respond dynamically to hormonal and nutrient availability; notably, excess oleic acid shortens cilia, promotes lipid droplet accumulation, and reduces Ca{superscript 2} responses to ATP and glucose. Disrupting cilia via knockdown of intraflagellar transport (IFT) genes produced similar defects and impaired autophagy. Finally, selective Ift88 knockout in tanycytes increased body weight and reduced thermogenic activity in female mice. These findings identify tanycytic cilia as key sensors regulating energy balance.

neuroscience↗

Dual Preconditioned Mesenchymal Stem Cells-Derived Culture Conditioned Media Augment Immunomodulation and Drive Metabolic Reprogramming in Acute Graft-versus-Host Disease

BackgroundThe toxicity associated with conventional conditioning regimens limits treatment outcomes in autoimmune disorders such as acute graft-versus-host disease (aGVHD). Developing effective adjunctive interventions to restore immune balance is therefore essential. This study investigated the immunomodulatory potential of mesenchymal stem cells (MSCs)-derived culture-conditioned media (CCM) from naive and preconditioned MSCs-hypoxic (MSCsHYP), apoptotic (MSCsAPO), and dual preconditioned (MSCsHYP+APO) in aGVHD. MethodsHuman MSCs isolated from bone marrow and Whartons Jelly were preconditioned under hypoxia (1% O2), apoptosis (1 {micro}M staurosporine, 24 h), or both. The immunoregulatory and antioxidant properties of their CCM were evaluated through T-cell proliferation assays, Treg induction, macrophage polarization, mitochondrial function, and T-cell bioenergetics. Comparative proteomic profiling of CCM from WJ-MSCs and WJ-MSCsHYP+APO co-cultured with aGVHD patient-derived activated PBMNCs was performed using LC-MS/MS, alongside in vivo validation in a chemotherapy-induced aGVHD murine model. ResultsWJ-MSCsHYP+APO-CCM exhibited superior immunomodulatory efficacy, suppressing T-cell proliferation, promoting Treg and Th2/Th9 differentiation, and driving M2 macrophage polarization. It reduced mitochondrial ROS, enhanced mitochondrial polarization, and shifted T-cell metabolism from glycolysis toward oxidative phosphorylation. Proteomic analysis revealed modulation of IL-12, IL-17, and JAK-STAT pathways, along with regulation of complement, coagulation, and metabolic cascades. Interaction with immune cells further enhanced its antioxidant and tissue-reparative properties via extracellular matrix remodeling. ConclusionDual preconditioning under hypoxia and apoptosis amplifies the immunomodulatory, antioxidant, and reparative efficacy of WJ-MSC-CCM, offering a potent non-cellular therapeutic strategy for aGVHD management. GRAPHICAL ABSTRACTImmunomodulatory and immune metabolic reprogramming potential of naive and preconditioned MSCs (MSCs, MSCsHYP, MSCsAPO, MSCsHYP+APO) derived CCM in Acute GVHD (created using Biorender.com) O_FIG O_LINKSMALLFIG WIDTH=95 HEIGHT=200 SRC="FIGDIR/small/686182v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@f7ed73org.highwire.dtl.DTLVardef@1063015org.highwire.dtl.DTLVardef@13ed827org.highwire.dtl.DTLVardef@e103c0_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

Sensitivity to ATR-CHK1 pathway inhibition in AML/MDS is enhanced by SRSF2 mutations and reduced by RUNX1 loss

SRSF2 mutations occur in up to 25% of acute myeloid leukemia (AML) and 17% of myelodysplastic syndrome (MDS) cases and are associated with poor prognosis, yet no mutation-directed therapy exists. Here, we aimed to identify therapeutically targetable vulnerabilities in MDS/AML with SRSF2 mutations. Ex vivo drug-sensitivity testing of bone marrow cells from AML patients and healthy donors showed that SRSF2-mutant cells are sensitive to inhibitors of CHK1, and WEE1 DNA damage response (DDR) kinases. To test causality, we engineered isogenic K562 cell line clones expressing SRSF2P95H/L/R mutations. RNA sequencing confirmed splicing aberrations characteristic of MDS/AML in these clones. We found that SRSF2P95H/L/R sensitize leukemia cells to ATR-CHK1-WEE1 inhibition. Bone marrow progenitors from Srsf2P95H and U2AF1S34F knock-in mice showed heightened sensitivity to CHK1 inhibition, corroborating the human data. In contrast, RUNX1 mutations were linked to resistance against CHK1 and WEE1 inhibition in SRSF2-mutant AML samples. Runx1 loss also caused resistance to CHK1 inhibitors in knock-in mouse progenitors harboring Srsf2P95H or U2AF1S34F, indicating that RUNX1 loss is a mechanism of resistance. In conclusion, SRSF2 and U2AF1 mutations are biomarkers of sensitivity to ATR-CHK1 pathway inhibitors, while RUNX1 mutations cause resistance. These biomarkers can support patient stratification in MDS/AML.

cancer biology↗

Transcriptional activation by MNRR1 is effected by recruiting p300 and can be induced by minimal peptides

Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1; also, CHCHD2, PARK22, AAG10), which functions in both the mitochondria and the nucleus, modulates mitochondrial function as well as cellular stress response. We have previously shown that stress response is predominantly mediated by its nuclear function as a transcriptional regulator; it operates at a conserved 8-bp DNA element that responds to moderate hypoxia, that we have termed the oxygen responsive element (ORE). This 8-bp element is the consensus DNA binding site for the transcription factor Recombination Signal Binding Protein For Immunoglobulin Kappa J Region (RBPJ{kappa}). We previously addressed the mechanism of nuclear MNRR1 by showing that it displaces the inhibitory transcriptional regulator CXXC-type zinc finger protein 5 (CXXC5), facilitating activation of genes harboring the ORE, and that it most effectively does so after deacetylation by SIRT1 at Lys119. A deacetyl mimetic mutant (K-R) rescues the phenotype in both genetic and environmental inflammatory models of defective mitochondrial function. Here we have refined the mechanism by which MNRR1 regulates transcription at the ORE. We show that MNRR1 interacts with RBPJ{kappa} and recruits the transcriptional co-activator p300 to facilitate transcription. We also show that a minimal domain of MNRR1 is sufficient to activate its nuclear function. Peptides based on this minimal domain can activate transcription by MNRR1 by enhancing p300 and RBPJ{kappa} interaction. MNRR1 peptides activate downstream pathways such as mitochondrial biogenesis and the unfolded protein response (UPRmt) in an in vitro model for MELAS.

cell biology↗

Stress-Induced Alteration of Small Extracellular Vesicles Drives Amyloid-Beta Sequestration and Exacerbates Alzheimer's Disease Pathogenesis

While small extracellular vesicles (sEVs) are implicated in amyloid-beta (A{beta}) trafficking, the mechanisms governing their interaction with A{beta} aggregates and plaque formation remain unresolved. Here, we report a paradigm-shifting discovery: sEVs undergo dynamic structural remodelling in response to stress, enabling selective binding to A{beta} aggregates-a phenomenon absent under normal physiological conditions. Using multimodal stressors, including mechanical (ultrasonication/agitation), physical (hyperthermia), and biological (oxidative damage), we demonstrate that stress-modified sEVs exhibit high-affinity binding to small A{beta} aggregates (SA) through scaffold reorganization, as validated by super-resolution microscopy and quantitative colocalization assays. Crucially, these remodelled sEVs act as potent carriers, enhancing SA internalization by neuronal cells in vitro. Strikingly, in post-mortem Alzheimers disease (AD) brains and APP-PS1 transgenic mice, sEVs were spatially enriched at amyloid plaque margins, suggesting a direct role in A{beta} sequestration and plaque expansion. Consistent with clinical relevance, sEVs isolated from AD patients exhibited an intrinsic SA-binding capacity, recapitulating stress-induced interactions observed experimentally. Our findings reveal that stress-primed sEVs function as pathological chaperones, binding to and internalizing A{beta} aggregates, thereby accelerating plaque nucleation and disease progression. This study provides the first evidence of stress-mediated sEV plasticity as a critical driver of A{beta} pathology, redefining therapeutic strategies targeting extracellular vesicle biology in neurodegenerative disorders. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/655679v2_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@107c76borg.highwire.dtl.DTLVardef@1b56848org.highwire.dtl.DTLVardef@d18636org.highwire.dtl.DTLVardef@1c26db4_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

A spatiotemporal cancer cell trajectory underlies glioblastoma heterogeneity

Cancer cells display highly heterogeneous and plastic states in glioblastoma, an incurable brain tumour. However, how these malignant states arise and whether they follow defined cellular trajectories across tumours is poorly understood. Here, we generated a deep single cell and spatial multi-omic atlas of human glioblastoma that pairs transcriptomic, epigenomic and genomic profiling of 12 tumours across multiple regions. We identify that glioblastoma heterogeneity is driven by spatially-patterned transitions of cancer cells from developmental-like states towards those defined by a glial injury response and hypoxia. This cellular trajectory regionalises tumours into distinct tissue niches and manifests in a molecularly conserved manner across tumours as well as genetically distinct tumour subclones. Moreover, using a new deep learning framework to map cancer cell states jointly with clones in situ, we show that tumour subclones are finely spatially intermixed through glioblastoma tissue niches. Finally, we show that this cancer cell trajectory is intimately linked to myeloid heterogeneity and unfolds across regionalised myeloid signalling environments. Our findings define a stereotyped trajectory of cancer cells in glioblastoma and unify glioblastoma tumour heterogeneity into a tractable cellular and tissue framework.

cancer biology↗

Multidimensional characterization of cellular ecosystems in Hodgkin lymphoma

The tissue architecture of classic Hodgkin Lymphoma (CHL) is unique among cancers and characterized by rare malignant Hodgkin and Reed-Sternberg cells that co-evolve with a complex ecosystem of immune cells in the tumor microenvironment (TME). The lack of a comprehensive systems-level interrogation has hindered the description of disease heterogeneity and clinically relevant molecular subtypes. Here, we employed an integrative, multimodal approach to characterize CHL tumors using malignant cell sequencing, spatial transcriptomics and imaging mass cytometry. We identified four molecular subtypes (CST, CN913, STB, and CN2P), each characterized by distinct clinical features, mutational patterns, malignant cell gene expression profiles, and spatial architecture involving immune cell populations. Functional modeling of CSF2RB mutations, a characteristic feature of the CST subtype, revealed dysregulated oncogenic signaling and unique TME crosstalk. These findings highlight the significance of multi-dimensional profiling in elucidating patterns of molecular alterations that drive immune ecosystems and underlie therapeutically exploitable vulnerabilities.

cancer biology↗

Predictive Modeling of acute Graft-versus-Host-Disease using Machine Learning on Immune Cell and Cytokine Profiles at Engraftment

BackgroundAcute Graft-versus-Host-Disease (aGvHD) is a major immune complication following allogenic hematopoietic stem cell transplantation (Allo-HSCT), initiated by conditioning regimen-associated tissue damage. It involves the complex interplay of immune cells and cytokines. Our study aims to leverage machine learning (ML) algorithms on the immune and cytokine profile of Allo-HSCT recipients to develop biomarker-based classification models to predict the onset of aGvHD at the time of engraftment. Materials and MethodsSeventy patients diagnosed with hematological disorders who had undergone Ist Allo-HSCT were recruited from All India Institute of Medical Sciences, New Delhi, India. Peripheral blood (PB) was collected from the patients at the time of engraftment, and the immune cell subtypes and cytokine profiles were analyzed using flow cytometry and ELISA respectively. The individual cell counts were then processed using basic ML models, including support vector classifier with RBF kernel, Decision Tree, and Random Forest, chosen for their mathematical simplicity and feature importance advantage of Decision Trees and Random Forests. Various data settings were utilized in the study: combined immune and cytokine counts, immune cell counts only, cytokine counts only, T-cell counts only, NK cell counts only, dendritic cell counts only, and B-cell counts only. These configurations were selected to investigate how different data sets impact the prediction of aGvHD before its onset. ResultsAt the engraftment flow cytometric analysis of reconstituted lymphocytes in patients who developed aGvHD revealed that there was a remarkable decrease in the ratio of CD4+/CD8+ T-cell and Tregs, with an increase in the cytotoxic regulatory NK-cell, dendritic cells, and B-cell. The levels of pro-inflammatory cytokines (IFN-{gamma}, IL-1{beta}, IP-10, TNF-, IL-17, IL-12p70, MIP-1, MIP-1{beta}, RANTES), and Th17-and Th1-cells were elevated with consequent decline of the levels of anti-inflammatory cytokine IL-10, IL-2, IL-4 and Th2-, Th9-cells. Machine learning based on 48 parameters [all immune cell subsets n=34 and all cytokines (n=14)]. The correlation heat map shows a higher correlation of aGvHD with the cytokine profile with or without immune cells (accuracy: 1), T-cell alone (accuracy: 0.96); NK-cell alone (accuracy: 0.93); dendritic cells alone (accuracy: 0.90), B-cell alone (accuracy: 0.86). ConclusionThe current models classify perfectly, indicating the potential for a ML algorithm in predicting the onset of aGvHD. However, a study with a larger sample size is required to validate these classification models and mitigate the risk of overfitting observed due to the consistently high performance. The study also highlights the potential of cytokine profiles as a viable alternative to T-cell counts, as evidenced by the correlation heat map and classifier models. These findings provide valuable insights into dataset requirements and future directions for integrating ML models into aGvHD prediction.

immunology↗