Biology subjects

Stransky, S.

Publications and source records attributed to Stransky, S..

18 recordsLinked to original sources

bioRxiv2026

Disconnect Between Succinate, Succinyl-CoA, and Histone Succinylation in Cells and Gastrointestinal Stromal Tumors with Succinate Dehydrogenase Deficiency

Background: Succinate dehydrogenase (SDH) is a heterotetrameric enzyme in both the tricarboxylic acid (TCA) cycle and the electron transport chain. SDH-deficiency has been shown to drive the oncogenesis of cancer types including gastrointestinal stromal tumors (GIST), paraganglioma/pheochromocytoma, and clear cell renal cell carcinoma. Previous work on SDH loss has shown increases in succinate, decreases in fumarate, as well as increase in the succinate to -ketoglutarate ratio, and correlated these changes to metabolite signaling and epigenetic dysregulation. Alterations to other TCA intermediates, including succinyl-CoA, the acyl-donor for succinylation, and the resulting cellular effects has not been fully explored. Methods: We used liquid chromatography high resolution mass spectrometry to quantify TCA cycle metabolites across the NCI-60 panel of cell lines, three SDH-competent and SDH-deficient model systems, and human tumor samples. We measured histone post-translational modifications in SHD-deficient and SDH-competent models and examined the correlation and potential pharmacological targeting of described desuccinylase enzymes by protein and cell assays. Results: We found an increase in succinyl-CoA in multiple SDH-deficient models, but no correlation between succinate to fumarate ratio and succinyl-CoA concentrations in the NCI-60. Interestingly, we found that while there was an increase in succinyl-CoA in the SDH-deficient cells, there was no corresponding increase in histone succinylation. We also observed a decrease in lysine malonylation and glutarylation, two other anionic lysine modifications. Cell viability and clonogenic assays revealed very weak or no selective effect of desuccinylase targeting in SDH-deficient models. Similarly, using SDH-deficient versus SDH-competent GIST patient samples, we examined both protein expression and metabolite abundance at the bulk tumor level and found no significant increase in succinyl-CoA or desuccinylase expression, despite the increase in succinate to fumarate ratio. Conclusions: We found that SDH-deficiency led to altered central carbon metabolism including increases to succinate and succinyl-CoA. Despite data that suggested the upregulation of desuccinylases may mediate a disconnect between succinyl-CoA concentration and histone succinylation, we found weak or no reductions in cell viability in response to pharmacological inhibition of desuccinylases. Additionally, no correlation of SDH loss with desuccinylase expression and succinyl-CoA in bulk tumor samples was observed.

cancer biology↗

bioRxiv2026

Histone succinylation directly inhibits Jumonji domain demethylases and stabilizes repressive chromatin states

Herein we uncover a relationship between histone succinylation and Jumonji (JmjC) domain-containing histone demethylases. We used quantitative proteomics and peptide pull-down assays to identify JmjC demethylases as candidate interactors with succinylated histone peptides. Succinyl-lysine peptides bind and inhibit the catalytic activity of JmjC demethylases in a dose-dependent manner. This includes KDM4D and KDM6B, which are responsible for the removal of the silencing marks H3K9me2/3 and H3K27me2/3. Supraphysiological sodium succinate treatment of HepG2/C3A cells increased the relative abundance of histone succinylation, H3K9me2/3, and H3K27me2/3. CUT&Tag and ChIP-mass spectrometry revealed the co-occurrence of succinylation with these repressive methylation marks, in addition to reduced transcriptional output. This work establishes a novel mechanistic link between metabolite abundance and chromatin regulation and suggests a role for histone succinylation in the maintenance of heterochromatin.

biochemistry↗

bioRxiv2025

Dual EZH1/2 inhibition enhances DNMT inhibitor efficacy in colon cancer through targeting H3K27me1

Abnormal DNA methylation patterning is a defining epigenetic hallmark of human cancer and is therapeutically targetable with DNA methyltransferase inhibitors (DNMTis). However, DNMTi-induced DNA hypomethylation promotes adaptive chromatin remodeling that limits molecular and therapeutic responses to these drugs. Here, we identify EZH1-dependent H3K27 mono-methylation (H3K27me1) as a previously unrecognized adaptive barrier to DNMTi response in colorectal cancer. While EZH2-selective inhibitors deplete H3K27me2 and H3K27me3, they preserve EZH1-dependent H3K27me1 at Polycomb-enriched genomic regions. In contrast, dual EZH1/2 inhibition eliminates all H3K27 methylation states and robustly synergizes with DNMTi to enhance transcriptional activation and growth suppression. Mechanistically, dual EZH1/2 inhibition induces a redistribution of p300/CBP-dependent H3K27 acetylation (H3K27ac), generating a therapy-associated bivalent chromatin state characterized by coexisting DNA methylation and H3K27ac. DNMT inhibition resolves this induced bivalency, enabling activation of tumor-suppressive transcriptional programs. At the same time, coordinated loss of H3K27me1 and gene-body DNA methylation, together with depletion of promoter-associated H3K27ac, suppresses MYC- and E2F-driven oncogenic transcription networks that define the cancer cell-intrinsic therapeutic response. Collectively, these findings establish EZH1-dependent H3K27me1 as a key mediator of adaptive epigenetic plasticity and provide mechanistic rationale for combining DNMT inhibitors with dual EZH1/2i inhibitors to reprogram chromatin and suppress oncogenic transcription in solid tumors. HighlightsO_LIEZH1-dependent H3K27me1 sustains an adaptive barrier to DNMT inhibitor response in colorectal cancer. C_LIO_LIDual EZH1/2 inhibition eliminates all H3K27 methylation states and remodels chromatin architecture. C_LIO_LIEZH inhibition induces a DNA methylation-H3K27ac bivalent chromatin state. C_LIO_LIDNMT and EZH1/2 co-inhibition reprograms enhancers and promoters to activate tumor-suppressive pathways. C_LIO_LICombination therapy suppresses MYC/E2F-driven oncogenic transcription, defining its cancer cell-intrinsic therapeutic efficacy. C_LI

cancer biology↗

bioRxiv2025

The H3K36M oncohistone inhibits NSD2 to activate a SETD2-dependent antiviral-like immune response in KRAS-driven lung cancer

Mutations in histone 3 at or near lysine 36 (H3K36) have dominantly acting oncogenic effects in multiple tumor types by limiting H3K36-directed methyltransferases. Paradoxically, we find that expression of the H3K36M oncohistone unexpectedly inhibits tumor formation in KRAS-driven lung adenocarcinoma by inducing a potent immune-mediated tumor clearance. Mechanistically, oncohistone expression derepresses endogenous retroviral element transcription, results in the accumulation of double-stranded RNA (dsRNA), and activates an innate antiviral-like immune response that eradicates tumor growth. Surprisingly, while inactivation of the H3K36 di-methyltransferase NSD2 replicated all effects of oncohistone expression, inactivation of the H3K36 tri-methyltransferase SETD2 abolished element derepression and all associated downstream anti-cancer effects that are induced by oncohistone expression. These observations restructure our understanding of the roles of H3K36 methylation, the consequences of its deregulation in cancer, and shape our expectations for therapeutic interventions targeting H3K36 methyltransferases.

cancer biology↗

bioRxiv2025

Loss of CARM1 alters the developmental programming of Glioma stem-like cells and creates a druggable NGFR/NTRK dependency

A key driver of Glioblastoma (GBM) heterogeneity and therapy resistance is the capacity of glioma stem-like cells (GSCs) to hijack developmental signaling programs. However, it remains unclear how GSCs regulate these adapted developmental signaling pathways and how these pathways might be therapeutically exploited. The arginine methyltransferase, CARM1, has been shown to play critical roles in maintaining stem cell pluripotency, preventing differentiation, and recently was discovered to be upregulated in Glioblastoma. To date, there is little to no understanding of the role that CARM1 plays in regulating developmental processes in Glioblastoma. To address this gap in knowledge, we applied a multi-omics approach to characterize developmental processes that are specifically regulated by CARM1 in GSCs. We found that loss of CARM1 results in dysregulation of several developmental markers: ARX, GFAP, NGFR, PDGFRA and results in both a proteomic and transcriptomic shift towards the radial glia cell lineage. Moreover, CARM1 depleted cells reprogram their signaling to develop an increased survival dependency on NGFR/NTRK signaling and are hypersensitive to the FDA approved brain penetrant NTRK inhibitor--Entrectinib. Mechanistically, we find that NFIA is a CARM1 substrate and can repress NGFR signaling just as CARM1 does, and thus the CARM1/NFIA relationship is likely a key regulator of NGFR/NTRK signaling in GSCs. Altogether, we demonstrate that CARM1 regulates the cell lineage of GSCs at the transcriptomic and proteomic level, and naturally represses NGFR/NTRK signaling--likely through CARM1 dependent methylation of NFIA. Further, CARM1 depletion leads GSCs to develop a survival dependency on NGFR/NTRK signaling and creates a therapeutic vulnerability to NTRK inhibition.

cancer biology↗

bioRxiv2024

CoREST Complex Inhibition Alters RNA Splicing to Promote Neoantigen Expression and Enhance Tumor Immunity

ABSTRACTEpigenetic complexes tightly regulate gene expression and colocalize with RNA splicing machinery; however, the consequences of these interactions are uncertain. Here, we identify unique interactions of the CoREST repressor complex with RNA splicing factors and their functional consequences in tumorigenesis. Using mass spectrometry, in vivo binding assays, and cryo-EM we find that CoREST complex-splicing factor interactions are direct and perturbed by the CoREST complex inhibitor, corin, leading to extensive changes in RNA splicing in melanoma and other malignancies. Using predictive machine learning models and MHC IP-MS, we identify thousands of corin-induced neopeptides derived from unannotated splice sites which generate immunogenic splice-neoantigens. Furthermore, corin reactivates the response to immune checkpoint blockade and promotes dramatic expansion of cytotoxic T cells in an immune cold melanoma model. CoREST complex inhibition thus represents a unique therapeutic opportunity in cancer which creates tumor-associated neoantigens that enhance the immunogenicity of current therapeutics. Statement of SignificanceWe identify a novel role of the CoREST transcriptional repressor complex in regulating pre-mRNA splicing and find that the small molecule inhibitor, corin, promotes alternative splicing events in cancer leading to neoantigen expression and T cell-mediated immunity. This represents a potential approach to promote immunoreactive neoantigen expression in immune-cold tumors.

cancer biology↗

bioRxiv2024

Productive mRNA Chromatin Escape is Promoted by PRMT5 Methylation of SNRPB

Protein Arginine Methyltransferase 5 (PRMT5) regulates RNA splicing and transcription by symmetric dimethylation of arginine residues (Rme2s/SDMA) in many RNA binding proteins. However, the mechanism by which PRMT5 couples splicing to transcriptional output is unknown. Here, we demonstrate that a major function of PRMT5 activity is to promote chromatin escape of a novel, large class of mRNAs that we term Genomically Retained Incompletely Processed Polyadenylated Transcripts (GRIPPs). Using nascent and total transcriptomics, spike-in controlled fractionated cell transcriptomics, and total and fractionated cell proteomics, we show that PRMT5 inhibition and knockdown of the PRMT5 SNRP (Sm protein) adapter protein pICln (CLNS1A) --but not type I PRMT inhibition--leads to gross detention of mRNA, SNRPB, and SNRPD3 proteins on chromatin. Compared to most transcripts, these chromatin-trapped polyadenylated RNA transcripts have more introns, are spliced slower, and are enriched in detained introns. Using a combination of PRMT5 inhibition and inducible isogenic wildtype and arginine-mutant SNRPB, we show that arginine methylation of these snRNPs is critical for mediating their homeostatic chromatin and RNA interactions. Overall, we conclude that a major role for PRMT5 is in controlling transcript processing and splicing completion to promote chromatin escape and subsequent nuclear export.

molecular biology↗

bioRxiv2024

EXOSC4 is recruited by histone H3 co-modified with K9me3 and acetylations to surveil non-coding transcription

Histones are hyper modified proteins that regulate chromatin accessibility and DNA readout. Co-existing post-translational modifications (PTMs) on histones affect interaction affinities of chromatin-associated proteins in ways that are still mostly unexplored. Here, we focus on the biological role of a specific histone code made of two PTMs with supposedly opposing biological functions, i.e. H3K9me3 marker of constitutive heterochromatin and H3K14ac benchmarking accessible chromatin. By applying multi-dimensional mass spectrometry, we demonstrated that EXOSC4 interacts with H3K9me3 + acetyls and affects post-transcriptional regulation. Specifically, EXOSC4 depletion leads to down-regulation of the RNA surveillance machinery and increased expression of non-coding transcripts, including anti-sense RNAs. Together, we elucidate the role of a co-modified histone tail and demonstrate its involvement in the RNA machinery and spurious transcription surveillance.

biochemistry↗

bioRxiv2024

PROSER1 Modulates DNA Demethylation through Dual Mechanisms to Prevent Syndromic Developmental Malformations

The link between DNA methylation and neurodevelopmental disorders is well established. However, how DNA methylation is fine-tuned - ensuring precise gene expression and developmental fidelity - remains poorly understood. PROSER1, a known TET2 interactor, was recently linked to a severe neurodevelopmental disorder. Here, we demonstrate that PROSER1 interacts with all TET enzymes and stabilizes chromatin-bound TET-OGT-PROSER1-DBHS (TOPD) complexes, which regulate DNA demethylation and developmental gene expression. Surprisingly, we find that PROSER1 also sequesters TET enzymes, preventing widespread demethylation and transposable element de-repression. Our findings identify PROSER1 as a key factor which both positively and negatively regulates DNA demethylation essential for mammalian neurodevelopment.

developmental biology↗

bioRxiv2024

Exosomes are vehicles for the stress-regulated secretion of histones

Histones are conserved nuclear proteins that function as part of the nucleosome in the regulation of chromatin structure and gene expression. Interestingly, extracellular histones populate biofluids from healthy individuals and when elevated may contribute to various acute and chronic diseases. It is generally assumed that most extracellular histones exist as nucleosomes, as components of extracellular chromatin. We analysed cell culture models under normal and stressed conditions to identify pathways of histone secretion. We report that core and linker histones localize to extracellular vesicles (EVs) and are secreted via the multivesicular body/exosome pathway. Upregulation of histone EV secretion occurs in response to cellular stress, with enhanced vesicle secretion and a shift towards a population of smaller EVs. Most histones were membrane associated with the outer surface of EVs. Degradation of EV-DNA did not impact significantly on EV-histone association. Individual histones or histone octamers bound strongly to liposomes and EVs, but nucleosomes did not, showing histones do not require DNA for EV binding. EV histones colocalized most frequently with the tetraspanin CD63 but using genetic or pharmacological intervention, we found that all known pathways of exosome biogenesis acted positively on histone secretion. Inhibition of autophagy and lysosomal degradation had a strong positive effect on EV histone release. Unexpectedly, EV-associated histones lacked the extensive post-translational modification of their nuclear counterparts, suggesting loss of PTMs may be involved in their trafficking or secretion. Our data does not support a significant role for EV-histones existing as nucleosomes. We show for the first time that histones are secreted from cells as membrane proteins via EVs/exosomes. This fundamental discovery provides support for further investigation of the biological activity of exosome associated histones and their role in disease.

cell biology↗

bioRxiv2023

Methylation of histone H3 lysine 36 is a barrier for therapeutic interventions of head and neck squamous cell carcinoma.

Approximately 20% of head and neck squamous cell carcinomas (HNSCC) exhibit reduced methylation on lysine 36 of histone H3 (H3K36me) due to mutations in histone methylase NSD1 or a lysine-to-methionine mutation in histone H3 (H3K36M). Whether such alterations of H3K36me can be exploited for therapeutic interventions is still unknown. Here, we show that HNSCC models expressing H3K36M can be divided into two groups: those that display aberrant accumulation of H3K27me3 and those that maintain steady levels of H3K27me3. The first group shows decreased proliferation, genome instability, and increased sensitivity to genotoxic agents, such as PARP1/2 inhibitors. In contrast, the H3K36M HNSCC models with steady H3K27me3 levels do not exhibit these characteristics unless H3K27me3 levels are elevated, either by DNA hypomethylating agents or by inhibiting the H3K27me3 demethylases KDM6A/B. Mechanistically, we found that H3K36M reduces H3K36me by directly impeding the activities of the histone methyltransferase NSD3 and the histone demethylase LSD2. Notably, we found that aberrant H3K27me3 levels induced by H3K36M expression is not a bona fide epigenetic mark in HNSCC since it requires continuous expression of H3K36M to be inherited. Moreover, increased sensitivity of H3K36M HNSCC models to PARP1/2 inhibitors solely depends on the increased H3K27me3 levels. Indeed, aberrantly high H3K27me3 levels decrease BRCA1 and FANCD2-dependent DNA repair, resulting in higher sensitivity to DNA breaks and replication stress. Finally, in support of our in vitro findings, a PARP1/2 inhibitor alone reduce tumor burden in a H3K36M HNSCC xenograft model with elevated H3K27me3, whereas in a H3K36M HNSCC xenograft model with consistent H3K27me3 levels, a combination of PARP1/2 inhibitors and agents that upregulate H3K27me3 proves to be successful. In conclusion, our findings underscore a delicate balance between H3K36 and H3K27 methylation, essential for maintaining genome stability. This equilibrium presents promising therapeutic opportunities for patients with H3K36me-deficient tumors.

cancer biology↗

bioRxiv2023

The catalytic-independent function of LSD1 modulates the epigenetic landscape of mouse embryonic stem cells

Lysine-specific histone demethylase 1 (LSD1), which demethylates mono- or di-methylated histone H3 on lysine 4 (H3K4me1/2), is essential for early embryogenesis and development. Here we show that LSD1 is dispensable for embryonic stem cell (ESC) self-renewal but is required for ESC growth and differentiation. Reexpression of a catalytically-dead LSD1 (LSD1MUT) recovers the proliferation capability of ESCs, yet the enzymatic activity of LSD1 is essential to ensure proper differentiation. Indeed, a gain of H3K4me1 in Lsd1 knockout (KO) ESCs does not lead to major changes in global gene expression programs related to stemness. However, ablation of LSD1 but not LSD1MUT results in decreased DNMT1 and UHRF1 proteins coupled to global hypomethylation. We show that both LSD1 and LSD1MUT control protein stability of UHRF1 and DNMT1 through interaction with the ubiquitin-specific peptidase 7 (USP7) and, consequently, inhibiting DNMT1 and UHRF1 ubiquitylation. Our studies elucidate for the first time a novel mechanism by which the scaffolding function of LSD1 controls DNA methylation in ESCs.

molecular biology↗

bioRxiv2023

A hyper-quiescent chromatin state formed during aging is reversed by regeneration

Epigenetic alterations are a key hallmark of aging but have been limitedly explored in tissues. Here, using naturally aged murine liver as a model and extending to other quiescent tissues, we find that aging is driven by temporal chromatin alterations that promote a refractory cellular state and compromise cellular identity. Using an integrated multi-omics approach, and the first direct visualization of aged chromatin we find that globally, old cells show H3K27me3-driven broad heterochromatinization and transcription suppression. At the local level, site-specific loss of H3K27me3 over promoters of genes encoding developmental transcription factors leads to expression of otherwise non-hepatocyte markers. Interestingly, liver regeneration reverses H3K27me3 patterns and rejuvenates multiple molecular and physiological aspects of the aged liver.

genomics↗

bioRxiv2022

Histone monoaminylation dynamics are regulated by a single enzyme and promote neural rhythmicity

Histone H3 monoaminylations at glutamine(Q) 5 represent an important family of epigenetic markers in neurons that play critical roles in the mediation of permissive gene expression (1, 2). We previously demonstrated that H3Q5 serotonylation(ser) and dopaminylation(dop) are catalyzed by the Transglutaminase 2 (TGM2) enzyme and alter both local and global chromatin states (3, 4). Here, we found that TGM2 additionally functions as an "eraser" of H3 monoaminylations that is capable of "re-writing" these epigenetic marks in cells, including a new class of this modification, H3Q5 histaminylation(his), which displays dynamic diurnal expression in brain and contributes to neural rhythmicity. We found that H3Q5his inhibits binding of the MLL1 complex to the H3 N-terminus and attenuates its methyltransferase activity on H3 lysine(K) 4. We determined that H3Q5 monoaminylation dynamics are dictated by local monoamine concentrations, which are utilized by TGM2. Taken together, we present here a novel mechanism through which a single chromatin regulatory enzyme is capable of sensing chemical microenvironments to affect the epigenetic states of cells. One sentence summaryA single enzyme, TGM2, bidirectionally controls H3 monoaminylation dynamics, which, in turn, facilitate neural rhythmicity.

molecular biology↗

bioRxiv2022

Investigation of reversible histone acetylation and dynamics in gene expression regulation using 3D liver spheroid model

BackgroundThree-dimensional (3D) cell culture has emerged as an alternative approach to 2D flat culture to model more accurately the phenotype of solid tissue in laboratories. Culturing cells in 3D more precisely recapitulates physiological conditions of tissues, as these cells reduce activities related to proliferation, focusing their energy consumption towards metabolism and homeostasis. ResultsHere, we demonstrate that 3D liver spheroids are a suitable system to model chromatin dynamics and response to epigenetics inhibitors. To delay necrotic tissue formation despite proliferation arrest, we utilize rotating bioreactors that apply active media diffusion and low shearing forces. We demonstrate that the proteome and the metabolome of our model resemble typical liver functions. We prove that spheroids respond to sodium butyrate (NaBut) treatment, an inhibitor of histone deacetylases (HDACi), by upregulating histone acetylations and transcriptional activation. As expected, NaBut treatment impaired specific cellular functions, including the energy metabolism. More importantly, we demonstrate that spheroids reestablish their original proteome and transcriptome, including pre-treatment levels of histone acetylation, metabolism, and protein expression once the standard culture condition is restored after treatment. Given the slow replication rate (>40 days) of cells in 3D spheroids, our model enables to monitor the recovery of approximately the same cells that underwent treatment, demonstrating that NaBut does not have long-lasting effects on histone acetylation and gene expression. These results suggest that histone acetylation has minimal epigenetics memory in our spheroids culture. ConclusionTogether, we established an innovative cell culture system that can be used to model anomalously decondensing chromatin in physiological cell growth and rule out epigenetics inheritance if cells recover the original phenotype after treatment. The transient epigenetics effects demonstrated here highlights the relevance of using a 3D culture model system that could be very useful in studies requiring long term drug treatment conditions that would not be possible using a 2D cell monolayer system.

cell biology↗

bioRxiv2022

Epigenetic dysregulation from chromosomal transit in micronuclei

Chromosomal instability (CIN) and epigenetic alterations are characteristics of advanced and metastatic cancers [1-4], yet whether they are mechanistically linked is unknown. Here we show that missegregation of mitotic chromosomes, their sequestration in micronuclei [5, 6], and subsequent micronuclear envelope rupture [7] profoundly disrupt normal histone post-translational modifications (PTMs), a phenomenon conserved across humans and mice as well as cancer and non-transformed cells. Some of the changes to histone PTMs occur due to micronuclear envelope rupture whereas others are inherited from mitotic abnormalities prior to micronucleus formation. Using orthogonal techniques, we show that micronuclei exhibit extensive differences in chromatin accessibility with a strong positional bias between promoters and distal or intergenic regions. Finally, we show that inducing CIN engenders widespread epigenetic dysregulation and that chromosomes which transit in micronuclei experience durable abnormalities in their accessibility long after they have been reincorporated into the primary nucleus. Thus, in addition to genomic copy number alterations, CIN can serve as a vehicle for epigenetic reprogramming and heterogeneity in cancer.

cancer biology↗

bioRxiv2021

Genotype-specific Features Reduce the Susceptibility of South American Yellow Fever Virus Strains to Vaccine-Induced Antibodies

The resurgence of yellow fever in South America has prompted mitigation through vaccination against the etiologic agent, yellow fever virus (YFV). Current vaccines are based on a virulent African isolate, and their capacity to induce neutralizing antibodies against the vaccine strain is widely used as a surrogate for protection. However, the sensitivity of genetically distinct South American strains to vaccine-induced antibodies is unknown. Here, we show that antiviral potency of the polyclonal antibody response in both U.S. and Brazilian vaccinees is attenuated against an emergent Brazilian strain. This reduction was attributable to genetic changes at two sites in the central domain II of the glycoprotein E, including the acquisition of an N-linked glycosylation site, which are unique to and shared among most South American YFV strains. Our findings call for a reevaluation of current approaches to YFV immunological surveillance in South America and suggest approaches for designing updated vaccines.

microbiology↗

bioRxiv2021

Cytoplasmic labile iron accumulates in aging stem cells perturbing a key rheostat for identity control

Bone marrow resident and rarely dividing haematopoietic stem cells (HSC) harbour an extensive self-renewal capacity to sustain life-long blood formation;1-5 albeit their function declines during ageing.6, 7 Various molecular mechanisms confer stem cell identity, ensure long-term maintenance and are known to be deregulated in aged stem cells.8, 9 How these programs are coordinated, particularly during cell division, and what triggers their ageing-associated dysfunction has been unknown. Here, we demonstrate that HSC, containing the lowest amount of cytoplasmic chelatable iron (labile iron pool)10 among hematopoietic cells, activate a limited iron response during mitosis. Engagement of this iron homeostasis pathway elicits mobilization and {beta}-oxidation of arachidonic acid and enhances stem cell-defining transcriptional programs governed by histone acetyl transferase Tip60/KAT5. We further find an age-associated expansion of the labile iron pool, along with loss of Tip60/KAT5-dependent gene regulation to contribute to the functional decline of ageing HSC, which can be mitigated by iron chelation. Together, our work reveals cytoplasmic redox active iron as a novel rheostat in adult stem cells; it demonstrates a role for the intracellular labile iron pool in coordinating a cascade of molecular events which reinforces HSC identity during cell division and to drive stem cell ageing when perturbed. As loss of iron homeostasis is commonly observed in the elderly, we anticipate these findings to trigger further studies into understanding and therapeutic mitigation of labile iron pool-dependent stem cell dysfunction in a wide range of degenerative and malignant pathologies.

cell biology↗