Biology subjects

D'Alessandro, A.

Publications and source records attributed to D'Alessandro, A..

At least 19 recordsLinked to original sources

bioRxiv2026

Maternal Folate Nutrition Programs Adult Hematopoietic Stem Cell Function Through Mitochondrial Remodeling

Folic acid fortification for the prevention of neural tube defects has been a cornerstone of public health policy for nearly three decades, but its broader consequences for other developing organ systems, particularly the hematopoietic system, are poorly studied. Hematopoietic stem cell (HSC) emergence overlaps developmentally with neural tube closure, and folate-dependent one-carbon metabolism is critical for nucleotide synthesis, cellular methylation, and redox balance, positioning folate as a candidate regulator of HSC programming. Using dietary models of maternal folate deficiency or supplementation in mice, we demonstrate that maternal folate acts as a dose-dependent developmental tuner of hematopoiesis, programming adult offspring HSC function through divergent mitochondrial and chromatin states. Maternal folate deficiency impaired adult HSC self-renewal, associated with mitochondrial defects, disrupted cristae, elevated proteotoxic stress and a stress-adapted chromatin landscape. In contrast, maternal folate supplementation enhanced HSC self-renewal accompanied by improved mitochondrial quality control and CDC42-associated organelle remodeling, and established chromatin states permissive for stem cell maintenance. Fetal HSC metabolomics identified shifts in one-carbon intermediates, pyruvate and lipid pools, suggesting that divergent fetal metabolic states provide substrate-level inputs that drive persistent and opposing chromatin programs in offspring HSCs. Our findings establish maternal folate availability as an unappreciated regulator of lifelong hematopoietic output demonstrating that a single maternal micronutrient, folate, is sufficient to program adult HSC function and regenerative capacity through persistent metabolic and mitochondrial programming.

cell biology↗

bioRxiv2026

A Female-Specific Microglial Redox Program Gates Susceptibility to Obesity

Chronic consumption of energy-dense, high-fat foods persistently exposes hypothalamic circuits that govern body weight to nutrient excess, progressively altering their activity and thereby promoting obesity. Microglia, the brain resident immune cells, sense circulating lipids, but how their intracellular metabolic programs adapt to chronic dietary excess, and how this contributes to obesity risk, is unclear. Here, we reveal a sex-dependent control of calorie overload by hypothalamic microglial cells. In females, but not males, microglia engage a protective metabolic program with increased antioxidant capacity and mitochondrial network remodeling, conferring resistance to early weight gain. Over time, activation of mTORC1 signaling in microglia disrupts mitochondrial functions and dismantles this transient resilience, culminating in weight gain. These findings identify microglial mTORC1 as a sex-specific switch between resilience and vulnerability to obesity and position microglial metabolism as a tractable target for sex-informed weight control.

neuroscience↗

bioRxiv2026

Enhancing Supercooled Red Blood Cell Storage: The Membrane-Stabilizing Effect of Ethanol

Hypothermic storage is constrained by the progressive depletion of energy reserves, curtailing the shelf-life of organs, cell therapies, and blood products. High sub-zero supercooling helps preserve energy homeostasis by slowing catabolic processes; however, the resulting injury in this setting is not primarily driven by energy depletion. Here, we investigated whether low-dose ethanol could prevent forms of injury that arise independently of disrupted energy homeostasis and remain unaddressed in supercooled storage. Human red blood cells treated with 4% (v/v) ethanol were stored 4 {degrees}C, -4 {degrees}C, or -8 {degrees}C and subject to a series of functional assessments and integrated metabolomic/lipidomic profiling after 21 and 42 days of storage. Metabolomics data showed that energy homeostasis was better preserved at lower temperatures, yet these supercooled conditions simultaneously intensified hemolysis and caused a marked depletion of lysophospholipid species that did not occur at 4 {degrees}C. Ethanol blunted these effects, cutting hemolysis by [~]50 % at -4 {degrees}C, by [~]85 % at -8 {degrees}C, and attenuating lysophospholipid depletion. These results uncover a previously unrecognized, lipid-centric injury that arises during supercooled storage and establish low-dose ethanol as a simple, readily deployable countermeasure that could help extend storage intervals of diverse biological systems. SUMMARYCellular preservation has traditionally focused on maintaining energy metabolism during hypothermic storage, but whether this is sufficient at high sub-zero temperatures remains unclear. Human red blood cells were stored for up to 42 days at 4{degrees}C, -4{degrees}C, or -8{degrees}C with or without 4% ethanol and evaluated using functional assays and integrated metabolomic and lipidomic profiling. Although supercooling preserved energy homeostasis, it increased hemolysis and caused pronounced lysophospholipid depletion. Ethanol reduced hemolysis by approximately 50% at -4{degrees}C and 85% at -8{degrees}C, attenuated lysophospholipid loss, and produced comparatively modest changes in cellular metabolism. These findings identify membrane integrity as a critical determinant of preservation outcome and support strategies that protect membrane stability alongside metabolic homeostasis.

cell biology↗

bioRxiv2026

Drosophila melanogaster lactate dehydrogenase deficiency recapitulates the exercise intolerance of human glycogen storage disease type XI

Lactate dehydrogenase A (LDHA) is a key glycolytic enzyme that commonly exhibits altered expression in human diseases such as cancers and neurodegeneration, making it a valuable disease biomarker and putative therapeutic target. However, any treatment targeting LDHA will also disrupt normal metabolism, underscoring the need to investigate physiological consequences of inhibiting this enzyme. We previously established the fruit fly Drosophila melanogaster as a genetic model for studying LDH function in the context of growth, metabolism, and development. Here we expand upon those studies by investigating a serendipitous observation that Ldh mutant larvae exhibit diet-dependent lethality. Using a multiomic approach, we discovered this diet-dependent phenotype is independent of nutritional composition. Instead, Ldh mutant larvae are exercise intolerant and display reduced mobility, rendering mutant larvae sensitive to food consistency. Moreover, tissue-specific analysis reveals that LDH activity within muscle and peripheral glia are essential for larval viability raised on solid food. Intriguingly, these phenotypes mirror the pathophysiology of LDHA deficiency (Glycogen Storage Disease Type XI; GSD Type XI) in humans, where mild symptoms are exacerbated by physical exertion and environmental stress. Together, our findings further highlight the value of using Drosophila to explore the developmental and physiological consequences of Ldh inhibition. SUMMARY STATEMENTLoss of lactate dehydrogenase in Drosophila causes exercise intolerance and diet-dependent lethality, revealing conditional phenotypes that mirror those associated with human LDH-A deficiency.

developmental biology↗

bioRxiv2026

Genetic architecture of the murine serum metabolome reveals carboxyl esterases as master regulators of circulating fatty acid metabolism

BackgroundThe systemic biochemical diversity of circulating metabolites and lipids reflects the integrated effects of genetic variation and environmental exposure. Metabolite quantitative trait locus (mQTL) studies in humans have established gene-metabolite associations, but genetic contributions can be obscured by sex, diet, age, medication use, and environmental exposures. Genetically diverse model systems offer a powerful complementary strategy to isolate genetic contributions to the biochemical diversity of the circulating metabolome. Methodology/Principal FindingsWe applied mass spectrometry profiling to serum samples in 541 mice from the Diversity Outbred (DO) population and identified 1,933 mQTL across 240 metabolites, 561 lipids, 43 oxylipins, and 4,465 MS/MS features. Co-mapping QTL, i.e., QTL hotspots, on chromosomes 8 and 17 implicated carboxyl esterase gene clusters (Ces1 and Ces2) as major regulators of circulating lipid remodeling and demonstrated genetic control of circulating protein/peptide-like features at the major histocompatibility complex and complement C3 loci. QTL hotspots on chromosomes 9 and 10 revealed previously unknown genetic drivers of lipid and amino acid metabolism. Comparisons with matched red blood cell mQTL revealed widespread compartment-specific genetic control. Conclusions/SignificanceCollectively, these findings provide a high-resolution map of the genetic regulation of the circulating metabolome, offering mechanistic insights that complement and extend human metabolic genetics.

genomics↗

bioRxiv2026

Exposure to perfluorooctanoic acid accelerates Drosophila melanogaster juvenile development and disrupts mitochondrial metabolism

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with poorly understood sublethal effects on insects. Perfluorooctanoic acid (PFOA), one of the most widely distributed legacy PFAS is increasingly recognized for altering organismal physiology beyond traditional toxicity endpoints. Here, we use the fruit fly Drosophila melanogaster as a model to examine how PFOA exposure during larval (juvenile) development reshapes insect life-history progression and metabolic homeostasis. Our studies reveal that at environmentally relevant concentrations (nM to low {micro}M), PFOA induces precocious expression of developmentally-regulated genes and leads to metabolic changes that persist into adulthood. At higher concentrations used to probe mechanism, PFOA accelerates larval development, disrupts mitochondrial membrane potential, and increases whole-organism metabolic heat production - results that suggest altered mitochondrial energetic efficiency. Consistent with this tradeoff, PFOA-exposed larvae that develop faster under permissive conditions exhibit heightened sensitivity to environmental stressors, including elevated temperature and reduced food hydration. Together, these findings demonstrate that PFOA disrupts metabolic and developmental processes in a dose- and context-dependent manner, highlighting sublethal effects that may influence insect resilience under environmental stress. SYNOPSIS STATEMENTHere we describe how PFOA alters the growth, development, and metabolism of the fruit fly Drosophila melanogaster. Specifically, we find that PFOA accelerates Drosophila juvenile growth while also rendering exposed larvae sensitive to environmental stress. These observations suggest that widespread PFOA contamination may impair the developmental fitness of insect populations.

pharmacology and toxicology↗

bioRxiv2026

Metabolic profiling of cultured erythroblast for the production of transfusion-ready cultured red blood cells

Transfusion-ready red blood cells can be cultured ex vivo from hematopoietic progenitors. Despite its promising outlook, a cultured transfusion unit cannot be produced at competitive costs. Large media volumes are required to maintain a maximum erythroblast cell density of 1-2.106 cells/mL during the erythroblast proliferation stage. To identify the origin of the cell density limitation, we investigated the cellular support and metabolomic phenotype using different media formulations and feeding regimens. Media that were exposed to an increasing density of erythroblasts (termed spent media) displayed a proportional decrease in erythroblast proliferation support. A 1:1 combination of spent media with fresh media (not previously exposed to the cells) restored growth for all tested conditions. Filtering both fresh and spent media with a 3 kDa cut-off filter, and subsequent recombination of the two fractions, indicated that exhaustion of the small molecular weight fraction (<3 kDa) was primarily responsible for growth limitation. We performed targeted and untargeted metabolomics analysis, for both the intra- and extracellular compartments, following seeding in fresh medium (12, 24, 36 h). We observed degradation of nucleosides, depletion of amino acids, and a decrease in intermediates of the glutathione-ascorbate, {gamma}-glutamyl and cysteine-methionine cycles. The latter compounds suggested an increase in oxidative stress in high density erythroblast cultures. Elimination of nucleosides from the medium led to a lower accumulation of purine salvage intermediates, and a 30% increase in cell productivity. In conclusion, we demonstrate that high-density erythroid cultures are subject to metabolic stress, defining critical constraints for scalable culture expansion.

cell biology↗

bioRxiv2026

Integrated Multiomics Links Metabolic and Inflammatory Remodeling to Arterial Stiffness After the 4,486-km Trans Europe Footrace

RationaleRegular aerobic exercise protects against vascular aging and reshapes the circulating molecular milieu, but the relation between vascular function, circulating molecules, and exercise dose at extreme volumes remains poorly defined. The vascular and molecular consequences of chronic, multi-stage ultra-endurance running are particularly unclear. ObjectiveTo define circulating molecular signatures associated with vascular dysfunction following the 64-stage, 4,486-km Trans Europe Foot Race (TEFR). Methods and ResultsIntegrated multiomics analysis (proteomics, lipidomics, metabolomics) of plasma from 27 finishers revealed a coordinated systemic shift driving an oxidative phenotype. Specifically, we identified altered arginine metabolism and a universal upregulation of lipotoxic ceramides consistent with incomplete fatty acid oxidation. In conjunction, we identified upregulation of innate immune system pathways including the acute phase response and the complement system. Central pulse wave velocity (cPWV) increased significantly after the race, consistent with arterial stiffening. To test whether the post-race circulating milieu could directly influence vascular mechanics, naive murine aortic rings were incubated with participant plasma. Post-race plasma acutely increased aortic elastic modulus, and this effect was attenuated by the superoxide dismutase mimetic TEMPOL, supporting a ROS-dependent component. In human aortic endothelial cells (HAECs), post-race plasma increased reactive oxygen species generation without detectable changes in eNOS phosphorylation, total eNOS abundance, or stimulated nitric oxide production. Endothelial ROS responses were associated with components of the terminal complement pathway. ConclusionsExtreme multi-stage ultra-endurance exercise induces a distinct systemic milieu associated with arterial stiffening through ROS-sensitive mechanisms. This response is characterized by remodeling of arginine-related metabolism, ceramide accumulation, innate immune activation, and oxidative stress, without evidence of reduced measured eNOS abundance or stimulated NO production. These findings identify candidate molecular pathways linking prolonged metabolic stress to vascular dysfunction.

physiology↗

bioRxiv2026

A population-scale red blood cell proteome reveals genetically encoded aging clocks predictive of hemolysis and blood donor activity

As the most abundant human cell and the foundation of transfusion medicine, red blood cells (RBCs) offer a unique readout of systemic health, yet they have never been characterized at population scale. We generated a proteome atlas of 13,091 blood donors with multi-omics longitudinal phenotyping, characterizing the influence of demographics and genetic variation on the reproducibility of RBC proteomes across donations. Elastic-net aging clocks captured biological aging with high accuracy and uncovered genetic regulators of {Delta}Age at FN1, C4/IKZF1, CRAT, PFAS, TRIM58. Across independent cohorts, {Delta}Age was accelerated in G6PD deficiency, sickle cell trait/disease, and iron deficiency, reversed by iron repletion, and slowed in high-frequency donors, linking molecular aging to brain iron/myelin and cognitive performance. Molecular aging signatures predicted storage, osmotic, and oxidative hemolysis, hemoglobin increments after transfusion, and long-term donor activity over 12-years. These results establish RBC proteomics as a scalable biomarker of aging, donor healthspan, and transfusion outcomes. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/710284v1_ufig1.gif" ALT="Figure 1"> View larger version (96K): org.highwire.dtl.DTLVardef@15bd46eorg.highwire.dtl.DTLVardef@1d7c107org.highwire.dtl.DTLVardef@1c1d870org.highwire.dtl.DTLVardef@168dc6f_HPS_FORMAT_FIGEXP M_FIG Dzieciatkowska et al. generate the first population-scale atlas of the RBC proteome across 13,000 donors and develop proteomic and metabolomic aging clocks that quantify biological age. Molecular {Delta}Age is reproducible across donations, genetically encoded and accelerated in G6PD deficiency, sickle cell trait/disease, and iron deficiency - yet reset by iron repletion, tracking with cognitive function and brain iron/myelin. RBC aging clocks predict hemolytic fragility, transfusion efficacy, and donor activity 12 years later. C_FIG HighlightsO_LIRBC proteome atlas of 13,091 donors reveals demographic and genetic programs C_LIO_LIGenetically encoded RBC aging clocks identify regulators of molecular {Delta}age C_LIO_LIMolecular aging features predict hemolysis and transfusion response across cohorts C_LIO_LIRBC molecular age forecasts long-term donor activity over a 12-year follow-up C_LI

biochemistry↗

bioRxiv2026

Aberrant oxidative metabolism selects for TET2-deficient hematopoietic stem and progenitor cells

The mechanism(s) driving selective expansion of mutant hematopoietic stem and progenitor cells (HSPC) in clonal hematopoiesis (CH) are incompletely understood. Here, we address the role of metabolism in selection for HSPC with loss of function mutations in TET2. Loss of Tet2 in murine HSPC triggers overexpression of glycolysis and oxidative phosphorylation genes and increased oxidative metabolism via an enlarged mitochondrial network. However, Tet2-deficient HSPC maintain a normal redox state. Strikingly, compound loss of the rate-limiting pentose phosphate pathway (PPP) enzyme glucose-6-phosphate dehydrogenase (G6PD) triggers increased reactive oxygen species and impairs the fitness of Tet2-deficient HSPC. We find that aberrant oxidative metabolism is also a feature of HSPC in human CH and clonal cytopenia of unknown significance (CCUS). Overall, our data point to aberrant metabolism as a critical and conserved driver of selection in TET2-deficient CH and identify the PPP as a crucial compensatory pathway needed to maintain their selective advantage. Statement of SignificanceThis study identifies oxidative metabolism as a critical driver of selection for TET2-deficient HSPC in clonal hematopoiesis (CH). It also demonstrates that cellular redox state is a vulnerability that impairs their fitness. These insights establish targetable metabolic pathway(s) that could be exploited in the setting of TET2 mutant CH.

cancer biology↗

bioRxiv2026

Conserved Molecular Responses to Arsenite Exposure in Drosophila melanogaster

Arsenic exposure is a pervasive global health threat strongly associated with increased risk of morbidities such as diabetes, cardiovascular disease, and cancer. Despite extensive studies describing the dangers of arsenic exposure, the molecular initiating events that link arsenic to chronic disease onset and progression remain poorly defined. To address this knowledge gap, we combined time-resolved transcriptomic and metabolomic profiling of adult Drosophila melanogaster exposed to sodium (meta) arsenite (NaAsO2). We uncovered coordinated, dose-dependent shifts in gene expression and metabolite abundance that activate canonical detoxification pathways and mirror arsenic-associated disease signatures in humans. Notably, flies rapidly upregulated heatshock and xenobiotic response gene networks, followed by biomarkers characteristic of diabetic states (elevated glucose, lactate, and methylglyoxal, for example). These findings reveal conserved molecular pathways that couple arsenic exposure to metabolic dysfunction and establish Drosophila as a powerful whole-organism model for identifying early biomarkers and mechanistic drivers of arsenic-induced disease phenotypes.

pharmacology and toxicology↗

bioRxiv2025

Deep Red Blood Cell Proteome Defines the Band 3 N-Terminus Interactome as a Regulator of Hypoxic Adaptation via BLVRB-Dependent S-Nitroso Transfer

Red blood cells (RBCs) have long been regarded as passive oxygen carriers, yet growing evidence reveals a complex, dynamic proteome independent of de novo gene expression. Here, we define the erythrocyte as an oxygen-responsive system organized around a Band 3 (SLC4A1)-centered metabolon. Using deep proteomics of ultra-pure RBCs and cross-linking interactomics, we identify biliverdin reductase B (BLVRB) as a previously unrecognized Band 3 interactor that binds the N-terminal cytosolic domain under normoxia and dissociates under hypoxia, when band 3-deoxyhemoglobin interactions increase threefold. This reversible interaction forms an oxygen-sensitive switch coupling structural, redox, and metabolic remodeling. In humanized mice, truncation of the Band 3 N-terminus disrupted glycolytic activation, reduced 2,3-bisphosphoglycerate synthesis, and impaired exercise tolerance despite preserved cardiopulmonary function, establishing the physiological relevance of this module. Population-scale proteome quantitative trait locus (pQTL) analyses revealed coordinated variation of SLC4A1 and BLVRB abundance but minimal association of biliverdin levels with BLVRB genotype, suggesting alternative functions beyond heme catabolism. Mechanistically, BLVRB Cys109 acts as a nitric oxide (NO) relay, trans-nitrosating glycolytic enzymes such as GAPDH at active site Cys152, transiently inhibiting glycolysis. This S-nitrosation-mediated feedback mirrors conserved mechanisms in plants, where GAPDH-SNO redirects carbon flow toward the Calvin-Benson cycle under nitrosative stress, revealing an evolutionary convergence in gas-responsive metabolic control. Collectively, our findings define a Band 3-BLVRB-hemoglobin axis that links oxygen sensing, NO signaling, and redox homeostasis, providing a unifying model for how an anucleate cell achieves environmental adaptability through reversible protein-protein interactions and post-translational chemistry. Graphic abstractIssaian et al. define the most comprehensive proteome of ultra-pure human red blood cells (3,775 proteins) and map the O2-dependent interactome, revealing a Band 3-BLVRB-hemoglobin module that links oxygen sensing to metabolic remodeling via reversible inhibitory S-nitrosation of GAPDH C152. In plants this redirects carbon toward photosynthesis, illustrating a conserved NO-dependent metabolic reprogramming mechanism across oxygen-regulated systems. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/691178v1_ufig1.gif" ALT="Figure 1"> View larger version (89K): org.highwire.dtl.DTLVardef@122468org.highwire.dtl.DTLVardef@114428dorg.highwire.dtl.DTLVardef@11d40c4org.highwire.dtl.DTLVardef@1870fb7_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDeep proteomics defines a complete, contamination-free RBC proteome (3,775 proteins) C_LIO_LICross-linking proteomics maps an oxygen-sensitive Band 3-centered interactome C_LIO_LIO2-dependent BLVRB-Band 3 binding regulates metabolism via S-nitrosation of GAPDH C_LIO_LIBand 3 N-terminus is required for hypoxic remodeling and exercise tolerance in vivo C_LI

biochemistry↗

bioRxiv2025

Genetic variation of human G6PD impacts Red Blood Cell transfusion efficacy

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common human enzymopathy, affects 6% of the global population, yet its impact on blood storage and transfusion efficacy remains undefined. We integrated genome-metabolome-proteome analyses of 13,091 blood donors (362 G6PD SNPs), validated in a recalled cohort (n=643), linked donor-recipient databases, humanized mouse models (canonical, African A- [V68M+N126D], Mediterranean [S188F]), and a prospective sickle cell disease study. Common G6PD variants reduced protein abundance, reprogrammed redox metabolism, and increased storage hemolysis. In mice, G6PD-deficient RBCs showed lower post-transfusion recovery, higher oxidative stress, and impaired renal oxygenation. Clinically, recipients of G6PD-deficient units exhibited smaller hemoglobin increments and reduced RBC L{superscript 1}Cr-survival (-8% at 24 h; -12% at 4 weeks). Structural studies revealed kinetic fragility for A- and thermodynamic fragility for Med-, linking genotype to protein instability and transfusion outcome. These findings identify donor G6PD genotype as a determinant of transfusion efficacy, supporting genotype-aware inventory-management strategies. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/689741v1_ufig1.gif" ALT="Figure 1"> View larger version (76K): org.highwire.dtl.DTLVardef@1897489org.highwire.dtl.DTLVardef@1420587org.highwire.dtl.DTLVardef@178e8ddorg.highwire.dtl.DTLVardef@1003b44_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2025

Epigenetic control of microglial developmental milestones from proliferative progenitors to efficient phagocytes

Early immune perturbations increase the risk of neurodegenerative and neurodevelopmental disorders, yet the mechanisms underlying the maturation of microglia, the resident immune cells of the brain parenchyma, remain poorly defined. Specifically, how proliferation, morphological differentiation, and phagocytosis are coordinated among microglia progenitors as they colonize the embryonic brain remains unclear. Here, we combined mathematical modeling with spatiotemporal analyses of the murine hippocampus and cerebellum from postnatal day 2 (P2) to P60 to reconstruct the trajectory of microglial development. We identified a proliferative-to-quiescent (P/Q) switch around P3/P4 that preceded the acquisition of morphological complexity and efficient phagocytosis and was accompanied by coordinated shifts in cell-cycle dynamics and metabolic state. Strikingly, this P/Q switch was recapitulated in repopulation contexts in mice and in the human fetal brain, where later stages displayed enhanced phagocytic function coupled to reduced proliferation. Perturbing the proliferative phase through pharmacological or genetic disruption of CSF1R signaling impaired subsequent microglial complexity and phagocytosis efficiency, revealing an unexpected reliance of phagocytosis on proliferation-driven colonization. Finally, we show that microglia stepwise maturation during development is associated with chromatin remodeling and driven by the epigenetic regulator Ikaros. Together, these findings uncover the sequential milestones of microglial development, revealing a potential period of early vulnerability and establishing an unexpected linkage between proliferation and phagocytosis essential to understanding how these processes are coordinated in neurodegenerative disorders.

neuroscience↗

bioRxiv2025

Bone Marrow Adipokine Mediates Hematopoietic Regeneration and Stem Cell Fitness

Bone marrow (BM) hematopoietic stem cells (HSCs) are exquisitely sensitive to cues from the BM microenvironment (ME), which is critical for their engraftment and regeneration following myeloablative stress. Retinoic acid signaling, acting on both HSCs and niche cells, has emerged as a central regulator of this process. Among ME components, BM adipocytes (BMAs), which can comprise up to 45% of BM volume and expand dramatically during the pancytopenic phase after myeloablation, play a previously underappreciated role in hematopoietic recovery. Here, we identify retinoid X receptor (RXR) signaling in BMAs as a key regulator of the adipokine Resistin, which promotes HSC self-renewal and functional fitness by activating NF-{kappa}B signaling. Conditional loss of RXR in adiponectin-expressing cells suppressed Resistin production, resulting in reduced NF-{kappa}B activity in HSCs, impaired self-renewal, and defective multilineage hematopoietic regeneration. Functionally, in vivo Resistin neutralization impaired hematopoietic reconstitution, whereas supplementation with either monomeric or dimeric Resistin enhanced HSC self-renewal and long-term lympho-hematopoietic reconstitution in an NF-{kappa}B-dependent manner. Together, these findings establish BMA-derived Resistin as an RXR-dependent, critical extrinsic regulator of HSC self-renewal and regenerative hematopoiesis, underscoring its essential role in lympho-myeloid reconstitution after myeloablation. Disclosures: The authors declare no relevant conflicts of interest.

physiology↗

bioRxiv2025

Choice of lipid supplementation for in vitro erythroid cell culture impacts reticulocyte yield and characteristics

Lipids, particularly cholesterol, are critical components of red blood cell (RBC) membranes, influencing protein function, cell stability, and deformability. Reticulocytes (young RBC) derived from in vitro erythroid cultures have been reported to possess less cholesterol than their native counterparts, compromising their functional integrity and lifespan. However, variability in starting materials and culture protocols between studies has hindered deQnitive conclusions regarding the nature and consequences of this lipid deQciency. Here, we evaluated the influence of lipid sources on reticulocyte quality using a well-established CD34 erythroid culture system. We compared the use of human AB-serum and Octaplas (solvent/detergent-treated pooled plasma) as lipid sources. Our results reveal that detergent-treated plasma leads to cholesterol-deQcient reticulocytes with impaired characteristics, including reduced Qltration yield, heightened osmotic fragility, and altered PIEZO1 activity. In contrast, AB-serum supported the generation of functionally stable reticulocytes, with cholesterol supplementation required to rescue the defects observed with plasma. Importantly, this study provides the Qrst integrated lipidomic, metabolomic, and proteomic characterisation of in vitro-derived reticulocytes cultured under distinct lipid conditions. These multi-omic datasets offer new insights into the consequences of reduced lipid availability during erythroid culture and offer new insights into how culture media affects the development and functionality of lab grown blood.

cell biology↗

bioRxiv2025

Caffeine Impairs Red Blood Cell Storage Quality by Dual Inhibition of ADORA2b Signaling and G6PD Activity

Caffeine is the most widely consumed psychoactive substance globally, yet its peripheral physiological effects remain incompletely understood. Leveraging comprehensive data from 13,091 blood donors in the REDS RBC-Omics study, we identify caffeine as a significant modulator of red blood cell (RBC) storage quality and transfusion outcomes. Elevated caffeine levels were reproducible across multiple donations from 643 recalled donors, selected based on their extremes in hemolytic propensity. Both in the screening and recalled cohorts, higher caffeine levels were associated with disrupted RBC metabolism, characterized by reduced glycolysis, depletion of adenylate pools or 2,3-bisphosphoglycerate, and increased markers of oxidative stress and osmotic fragility, including kynurenine accumulation. These observations were recapitulated in plasma and RBCs of eight volunteers upon consumption of a cup of coffee independently of brewing method (Chemex vs espresso). Clinically, elevated caffeine correlated with increased hemolysis and lower post-transfusion hemoglobin increments, especially pronounced in recipients transfused with RBCs from donors carrying common polymorphisms in the ADORA2b gene, a key regulator of RBC metabolism in hypoxia. These human findings were mechanistically validated using a murine model deficient in ADORA2b, which demonstrated impaired glycolytic flux, compromised antioxidant defenses - including caffeine-dependent direct inhibition of recombinantly-expressed glucose 6-phosphate dehydrogenase, and decreased transfusion efficacy (lower hemoglobin increments, higher bilirubin post-transfusion), effects further exacerbated by caffeine exposure during storage. Our study positions caffeine consumption as a modifiable factor in blood transfusion practice, advocating for precision strategies that integrate genetic and exposome factors, and identifies metabolic interventions to enhance blood quality and clinical outcomes. One sentence summaryCaffeine consumption and genetic variants in the ADORA2b receptor synergistically impair red blood cell metabolism and transfusion efficacy, revealing a modifiable exposome-gene interaction for precision transfusion medicine.

biochemistry↗

bioRxiv2025

Integrative Multi-Omics Analysis Identifies Nuclear Factor I as a Key Driver of Dysregulated Purine Metabolism in DIPG

Diffuse intrinsic pontine glioma (DIPG) is a devastating brainstem cancer in children, with a median survival of under one year and limited treatment options. Over 80% of DIPGs possess a H3K27M mutation. To identify metabolic vulnerabilities linked to this mutation, we utilized a multi-omics approach in H3K27M-expressing cells, patient-derived cell lines, and mouse models. We show that by reprogramming chromatin landscape the mutation aberrantly induces NFI transcriptional activity, leading to misregulated purine metabolism. The mutation amplifies purine biosynthesis and degradation via the enzymes ATIC and PNP, respectively. Unregulated purine degradation relieves the negative feedback of purines on their own synthesis allowing continuous synthesis, use and degradation making DIPGs reliant on purine biosynthesis. Targeting ATIC reduced tumor progression and improved survival in mice. We propose ATIC as a potential novel target in DIPG.

cancer biology↗