Hematopoietic Stem Cell Aging Research Articles

The Effect of Circulating Exosomes Obtained from Young and Old Individuals on the Aging related hTERT and P16 Expression in Hematopoietic Stem Cells

Introduction: Functional reduction of telomeres can induce DNA damage response through cell cycle checkpoints and contribute to the senescence of stem cells. The effect of exosomes on the aging and rejuvenation of hematopoietic stem cells (HSCs) is not well known. Therefore, the present study is designed to examine the impact of plasma exosomes derived from young and old individuals on hTERT and P16 expression involved in the cellular aging process. Methods: Exosomes isolated from four young (Y-Exo) and four old (O-Exo) men were evaluated for CD63 protein expression, morphology, size and zeta potential. HSCs were treated with exosomes, and then, the cell viability and the mRNA expression (hTERT and P16) were evaluated using MTT and qRT-PCR methods, respectively. To measure the hTERT protein level, a western blot technique was performed. Results: The gene expression of hTERT was significantly decreased in HSCs treated with 5 μg/ml (O5-Exo) and 10 μg/ml (O10-Exo) doses of exosomes obtained from elderly individuals compared to the cells treated with young exosomes and the untreated HSCs (p < 0.05). In addition, there was a profound elevation of hTERT protein in the HSCs treated with both doses of young exosomes in comparison with the cells treated with both doses of old exosomes (p < 0.05). Moreover, P16 expression was markedly upregulated in the O5-Exo and O10-Exo groups compared to the untreated group (p < 0.05). Conclusion: Our findings reinforce the concept that depending on the age of individuals, circulating exosomes may acquire properties that affect the pathways involved in the aging process in HSCs.

DNA methylation drives hematopoietic stem cell aging phenotypes after proliferative stress.

Aging of hematopoietic stem cells (HSCs) is implicated in various aging phenotypes, including immune dysfunction, anemia, and malignancies. The role of HSC proliferation in driving these aging phenotypes, particularly under stress conditions, remains unclear. Therefore, we induced forced replications of HSCs in vivo by a cyclical treatment with low-dose fluorouracil (5FU) and examined the impact on HSC aging. Our findings show that proliferative stress induces several aging phenotypes, including altered leukocyte counts, decreased lymphoid progenitors, accumulation of HSCs with high expression of Slamf1, and reduced reconstitution potential, without affecting stem cell self-renewal capacity. The divisional history of HSCs was imprinted in the DNA methylome, consistent with functional decline. Specifically, DNA methylation changes included global hypermethylation in non-coding regions and similar frequencies of hypo- and hyper-methylation at promoter regions, particularly affecting genes targeted by the PRC2 complex. Importantly, initial forced replication promoted DNA damage repair accumulated with age, but continuous proliferative stress led to the accumulation of double-strand breaks, independent of functional decline. Overall, our results suggest that HSC proliferation can drive some aging phenotypes primarily through epigenetic mechanisms, including DNA methylation changes.

CD38 and the mitochondrial calcium uniporter contribute to age-related hematopoietic stem cell dysfunction.

Hematopoietic stem cells (HSCs) are the multipotent progenitors of all immune cells. During aging, their regenerative capacity decreases for reasons that are not well understood. Recently, Song et al investigated the roles of two metabolic proteins in age-related HSC dysfunction: CD38 (a membrane-bound NADase) and the mitochondrial calcium uniporter that transports calcium into the mitochondrial matrix. They found that the interplay between these proteins is deranged in aged HSCs, contributing to their diminished renewal capacity. These findings implicate compromised nicotinamide adenine dinucleotide metabolism as underlying HSC dysfunction in aging.

Long-term longitudinal analysis of 4,187 participants reveals insights into determinants of clonal hematopoiesis

Clonal hematopoiesis of indeterminate potential (CHIP) is linked to diverse aging-related diseases, including hematologic malignancy and atherosclerotic cardiovascular disease (ASCVD). While CHIP is common among older adults, the underlying factors driving its development are largely unknown. To address this, we performed whole-exome sequencing on 8,374 blood DNA samples collected from 4,187 Atherosclerosis Risk in Communities Study (ARIC) participants over a median follow-up of 21 years. During this period, 735 participants developed incident CHIP. Splicing factor genes (SF3B1, SRSF2, U2AF1, and ZRSR2) and TET2 CHIP grow significantly faster than DNMT3A non-R882 clones. We find that age at baseline and sex significantly influence the incidence of CHIP, while ASCVD and other traditional ASCVD risk factors do not exhibit such associations. Additionally, baseline synonymous passenger mutations are strongly associated with CHIP status and are predictive of new CHIP clone acquisition and clonal growth over extended follow-up, providing valuable insights into clonal dynamics of aging hematopoietic stem and progenitor cells. This study also reveals associations between germline genetic variants and incident CHIP. Our comprehensive longitudinal assessment yields insights into cell-intrinsic and -extrinsic factors contributing to the development and progression of CHIP clones in older adults.

RNA Modifications Shape Hematopoietic Stem Cell Aging: Beyond the Code.

Hematopoietic system aging is characterized by both hematopoietic stem cell (HSC) and niche degeneration resulting in myeloid lineage-biased differentiation, reduced B cell and T cell lymphopoiesis, increased HSC mobilization, and fat deposition in the bone marrow. Both alterations in RNA splicing and editing during HSC aging contribute to increased myeloid lineage skewing and inflammation-responsive transcription factors, underscoring the importance of epitranscriptomic mechanisms in the acquisition of an age-related phenotype.

Deubiquitinases at the interplay between hematopoietic stem cell aging and myelodysplastic transformation.

Hematopoietic stem cells (HSC) maintain blood production throughout life. Nevertheless, HSC functionality deteriorates upon physiological aging leading to the increased prevalence of haematological diseases and hematopoietic malignancies in the elderly. Deubiquitinating enzymes (DUBs) by reverting protein ubiquitination ensure proper proteostasis, a key process in HSC maintenance and fitness.

An NAD+-dependent metabolic checkpoint regulates hematopoietic stem cell activation and aging.

How hematopoietic stem cells (HSCs) maintain metabolic homeostasis to support tissue repair and regeneration throughout the lifespan is elusive. Here, we show that CD38, an NAD+-dependent metabolic enzyme, promotes HSC proliferation by inducing mitochondrial Ca2+ influx and mitochondrial metabolism in young mice. Conversely, aberrant CD38 upregulation during aging is a driver of HSC deterioration in aged mice due to dysregulated NAD+ metabolism and compromised mitochondrial stress management. The mitochondrial calcium uniporter, a mediator of mitochondrial Ca2+ influx, also supports HSC proliferation in young mice yet drives HSC decline in aged mice. Pharmacological inactivation of CD38 reverses HSC aging and the pathophysiological changes of the aging hematopoietic system in aged mice. Together, our study highlights an NAD+ metabolic checkpoint that balances mitochondrial activation to support HSC proliferation and mitochondrial stress management to enhance HSC self-renewal throughout the lifespan, and links aberrant Ca2+ signaling to HSC aging.

A metabolic atlas of blood cells in young and aged mice identifies uridine as a metabolite to rejuvenate aged hematopoietic stem cells.

Aging of hematopoietic stem cells (HSCs) is accompanied by impaired self-renewal ability, myeloid skewing, immunodeficiencies and increased susceptibility to malignancies. Although previous studies highlighted the pivotal roles of individual metabolites in hematopoiesis, comprehensive and high-resolution metabolomic profiles of different hematopoietic cells across ages are still lacking. In this study, we created a metabolome atlas of different blood cells across ages in mice. We reveal here that purine, pyrimidine and retinol metabolism are enriched in young hematopoietic stem and progenitor cells (HSPCs), whereas glutamate and sphingolipid metabolism are concentrated in aged HSPCs. Through metabolic screening, we identified uridine as a potential regulator to rejuvenate aged HSPCs. Mechanistically, uridine treatment upregulates the FoxO signaling pathway and enhances self-renewal while suppressing inflammation in aged HSCs. Finally, we constructed an open-source platform for public easy access and metabolomic analysis in blood cells. Collectively, we provide a resource for metabolic studies in hematopoiesis that can contribute to future anti-aging metabolite screening.

Epidermal growth factor augments the self-renewal capacity of aged hematopoietic stem cells

Hematopoietic aging is associated with decreased hematopoietic stem cell (HSC) self-renewal capacity and myeloid skewing. We report that culture of bone marrow (BM) HSCs from aged mice with epidermal growth factor (EGF) suppressed myeloid skewing, increased multipotent colony formation, and increased HSC repopulation in primary and secondary transplantation assays. Mice transplanted with aged, EGF-treated HSCs displayed increased donor cell engraftment within BM HSCs and systemic administration of EGF to aged mice increased HSC self-renewal capacity in primary and secondary transplantation assays. Expression of a dominant negative EGFR in Scl/Tal1+ hematopoietic cells caused increased myeloid skewing and depletion of long term-HSCs in 15-month-old mice. EGF treatment decreased DNA damage in aged HSCs and shifted the transcriptome of aged HSCs from genes regulating cell death to genes involved in HSC self-renewal and DNA repair but had no effect on HSC senescence. These data suggest that EGFR signaling regulates the repopulating capacity of aged HSCs.

SDHAF1 confers metabolic resilience to aging hematopoietic stem cells by promoting mitochondrial ATP production

Aging generally predisposes stem cells to functional decline, impairing tissue homeostasis. Here, we report that hematopoietic stem cells (HSCs) acquire metabolic resilience that promotes cell survival. High-resolution real-time ATP analysis with glucose tracing and metabolic flux analysis revealed that old HSCs reprogram their metabolism to activate the pentose phosphate pathway (PPP), becoming more resistant to oxidative stress and less dependent on glycolytic ATP production at steady state. As a result, old HSCs can survive without glycolysis, adapting to the physiological cytokine environment in bone marrow. Mechanistically, old HSCs enhance mitochondrial complex II metabolism during stress to promote ATP production. Furthermore, increased succinate dehydrogenase assembly factor 1 (SDHAF1) in old HSCs, induced by physiological low-concentration thrombopoietin (TPO) exposure, enables rapid mitochondrial ATP production upon metabolic stress, thereby improving survival. This study provides insight into the acquisition of resilience through metabolic reprogramming in old HSCs and its molecular basis to ameliorate age-related hematopoietic abnormalities.

Tetrahydroxy stilbene glucoside rejuvenates aging hematopoietic stem cells with predilection for lymphoid differentiation via AMPK and Tet2

IntroductionAging of hematopoietic stem cells (HSCs) has emerged as an important challenge to human health. Recent advances have raised the prospect of rejuvenating aging HSCs via specific medical interventions, including pharmacological treatments. Nonetheless, efforts to develop such drugs are still in infancy until now. ObjectivesWe aimed to screen the prospective agents that can rejuvenate aging HSCs and explore the potential mechanisms. MethodsWe screened a set of natural anti-aging compounds through oral administration to sub-lethally irradiated mice, and identified 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (TSG) as a potent rejuvenating agent for aging HSCs. Then naturally aged mice were used for the follow-up assessment to determine the HSC rejuvenating potential of TSG. Finally, based on the transcriptome and DNA methylation analysis, we validated the role of the AMP-activated protein kinase (AMPK)-ten-eleven-translocation 2 (Tet2) axis (the AMPK-Tet2 axis) as the underlying mechanisms of TSG for ameliorating HSCs aging. ResultsTSG treatment not only significantly increased the absolute number of common lymphoid progenitors (CLPs) along with B lymphocytes, but also boosted the HSCs/CLPs repopulation potential of aging mice. Further elaborated mechanism research demonstrated that TSG supplementation restored the stemness of aging HSCs, as well as promoted an epigenetic reprograming that was associated with an improved regenerative capacity and an increased rate of lymphopoiesis. Such effects were diminished when the mice were co-treated with an AMPK inhibitor, or when it was performed in Tet2 knockout mice as well as senescent cells assay. ConclusionTSG is effective in rejuvenating aging HSCs by modulating the AMPK- Tet2 axis and thus represents a potential candidate for developing effective HSC rejuvenating therapies.

Aging-induced MCPH1 translocation activates necroptosis and impairs hematopoietic stem cell function.

DNA damage contributes to the aging of hematopoietic stem cells (HSCs), yet the underlying molecular mechanisms are not fully understood. In this study, we identified a heterogeneous functional role of microcephalin (MCPH1) in the nucleus and cytoplasm of mouse HSCs. In the nucleus, MCPH1 maintains genomic stability, whereas in the cytoplasm, it prevents necroptosis by binding with p-RIPK3. Aging triggers MCPH1 translocation from cytosol to nucleus, reducing its cytoplasmic retention and leading to the activation of necroptosis and deterioration of HSC function. Mechanistically, we found that KAT7-mediated lysine acetylation within the NLS motif of MCPH1 in response to DNA damage facilitates its nuclear translocation. Targeted mutation of these lysines inhibits MCPH1 translocation and, consequently, compromises necroptosis. The dysfunction of necroptosis signaling, in turn, improves the function of aged HSCs. In summary, our findings demonstrate that DNA damage-induced redistribution of MCPH1 promotes HSC aging and could have broader implications for aging and aging-related diseases.

Why an integrated view of gene expression studies on hematopoiesis in mouse aging is better than the sum of their parts

Globally, the human population is aging, with an increased proportion of people in “old age” (over 60 years). This trend leads to a growing demand in aging research, stimulating studies in animal models such as mice, fish, and invertebrates. Recently, we published a research summary on the aging of hematopoietic stem cells (HSCs) in C57BL/6 mice based on 12 gene expression datasets. Here, I discuss in greater detail the added value of taking an integrated view, rather than considering each publication separately, to determine genes involved in aging. Considerable variation exists between lists of differentially expressed (DE) genes in HSCs, comparing young and old mice. This variation can result from factors such as inconsistent definitions of “young” and “old”, technical variations and variations between laboratory mouse strains. We previously demonstrated that the variation between gene lists could be circumvented by forming a unified list of DE genes—the “aging list”—with citation indexes attached. The most frequently detected DE genes [approximately 200 most cited, which we named the “aging signature” (AS)] were highly consistent across publications. Gene Ontology classification of the AS list identified additional sources of variation between studies: one comes from the specifics of how the data are collected and analyzed; another comes from inconsistencies between how we define the gene categories. As discussed, overcoming these variations is the next challenge toward an integral approach to our systematic knowledge of the aging process.

Epigenetics of hematopoietic stem cell aging.

The development of new antiaging medicines is of great interest to the current elderly and aging population. Aging of the hematopoietic system is attributed to the aging of hematopoietic stem cells (HSCs), and epigenetic alterations are the key effectors driving HSC aging. Understanding the epigenetics of HSC aging holds promise of providing new insights for combating HSC aging and age-related hematological malignancies. Aging is characterized by the progressive loss of physiological integrity, leading to impaired function and increased vulnerability to death. During aging, the HSCs undergo both quantitative and qualitative changes. These functional changes in HSCs cause dysregulated hematopoiesis, resulting in anemia, immune dysfunction, and an increased risk of hematological malignancies. Various cell-intrinsic and cell-extrinsic effectors influencing HSC aging have also been identified. Epigenetic alterations are one such mechanism. Cumulative epigenetic alterations in aged HSCs affect their fate, leading to aberrant self-renewal, differentiation, and function of aged HSCs. In turn, these factors provide an opportunity for aged HSCs to expand by modulating their self-renewal and differentiation balance, thereby contributing to the development of hematological malignancies.

Variation in mesenchymal KITL/SCF and IGF1 expression in middle age underlies steady-state hematopoietic stem cell aging

AbstractIntrinsic molecular programs and extrinsic factors including proinflammatory molecules are understood to regulate hematopoietic aging. This is based on foundational studies using genetic perturbation to evaluate causality. However, individual organisms exhibit natural variation in the hematopoietic aging phenotypes and the molecular basis of this heterogeneity is poorly understood. Here, we generated individual single-cell transcriptomic profiles of hematopoietic and nonhematopoietic cell types in 5 young adult and 9 middle-aged C57BL/6J female mice, providing a web-accessible transcriptomic resource for the field. Among all assessed cell types, hematopoietic stem cells (HSCs) exhibited the greatest phenotypic variation in expansion among individual middle-aged mice. We computationally pooled samples to define modules representing the molecular signatures of middle-aged HSCs and interrogated, which extrinsic regulatory cell types and factors would predict the variance in these signatures between individual middle-aged mice. Decline in signaling mediated by adiponectin, kit ligand (KITL) and insulin-like growth factor 1 (IGF1) from mesenchymal stromal cells (MSCs) was predicted to have the greatest transcriptional impact on middle-aged HSCs, as opposed to signaling mediated by endothelial cells or mature hematopoietic cell types. In individual middle-aged mice, lower expression of Kitl and Igf1 in MSCs was highly correlated with reduced lymphoid lineage commitment of HSCs and increased signatures of differentiation-inactive HSCs. These signatures were independent of expression of aging-associated proinflammatory cytokines including interleukin-1β (IL-1β), IL-6, tumor necrosis factor α and RANTES. In sum, we find that Kitl and Igf1 expression are coregulated and variable between individual mice at the middle age and expression of these factors is predictive of HSC activation and lymphoid commitment independently of inflammation.

Cyclophilin A supports translation of intrinsically disordered proteins and affects haematopoietic stem cell ageing

Loss of protein function is a driving force of ageing. We have identified peptidyl-prolyl isomerase A (PPIA or cyclophilin A) as a dominant chaperone in haematopoietic stem and progenitor cells. Depletion of PPIA accelerates stem cell ageing. We found that proteins with intrinsically disordered regions (IDRs) are frequent PPIA substrates. IDRs facilitate interactions with other proteins or nucleic acids and can trigger liquid–liquid phase separation. Over 20% of PPIA substrates are involved in the formation of supramolecular membrane-less organelles. PPIA affects regulators of stress granules (PABPC1), P-bodies (DDX6) and nucleoli (NPM1) to promote phase separation and increase cellular stress resistance. Haematopoietic stem cell ageing is associated with a post-transcriptional decrease in PPIA expression and reduced translation of IDR-rich proteins. Here we link the chaperone PPIA to the synthesis of intrinsically disordered proteins, which indicates that impaired protein interaction networks and macromolecular condensation may be potential determinants of haematopoietic stem cell ageing.

Abstract 4398: TET2 accelerates clonal hematopoiesis in an age-dependent manner

Abstract Aging is a process of systemic deterioration and the most significant risk factor for cancers. Clonal hematopoiesis (CH) commonly occurs with aging and links to higher mortality, leukemia risk, and cardiovascular diseases. Age-related CH involves the abnormal clonal expansion of hematopoietic stem cells (HSCs) bearing somatic mutations in genes frequently mutated in leukemia, including genes encoding epigenetic regulators, such as the DNA demethylase TET2. While such mutations are known to alter the HSC epigenome, the mechanisms through which these mutations drive HSC self-renewal, myeloid transformation, and inflammatory response remain elusive. In this study, we hypothesize that aging and CH mutations cooperatively reshape the HSC transcriptomic landscape and enhancing HSC competitive advantage that facilitates clonal expansion. Recently, TET2-mutant CH in humans has been strongly associated with epigenetic age acceleration. Using single-cell multi-omic analyses and flow-cytometric phenotyping, we demonstrated, for the first time, that HSC aging processes at transcriptomic, epigenomic, and cellular levels are accelerated by Tet2 deficiency in mice, in an age-dependent manner. Tet2-deficient HSCs increase the HSC aging scores at an older age of greater than or equal to 16 months, but not at a young or mid-age, based on gene expression and chromatin accessibility at a single-cell resolution. This age acceleration was further validated by epigenetic clock analysis of DNA methylation mapping. Moreover, we found that Tet2 deficiency drives a significant expansion of HSCs, a cellular hallmark of HSC aging, in an age-dependent manner. Specifically, we observed increased expression of S100a6, Cdk6, Egr1 in Tet2-deficient HSCs from older mice, suggesting that Tet2 deficiency hijacks the HSC expansion strategy during HSC aging by enhanced self-renewal. We also observed that the differentially expressed genes between Tet2-deficient older HSCs and control older HSCs are associated with open chromatin accessibility. Many of these genes are enriched in the targets of specific transcription factors (TFs), such as Egr1, Creb1, Stat family and Hoxb8. These target genes play critical roles in inflammatory pathways and HSC functions. In conclusion, our findings reveal that Tet2 deficiency significantly contributes to the acceleration of HSC aging, and hijacks the HSC expansion strategy (e.g., self-renewal) during HSC aging, which exacerbates age-related clonal hematopoiesis. By elucidating the transcriptomic and epigenomic alterations in Tet2-deficient HSCs, our study provides novel insights into how age and somatic mutations collaborate to promote the pathogenesis of age-related hematological diseases. These discoveries not only enhance our understanding of HSC aging mechanisms but also offer potential biomarkers for early detection and targets for therapeutic intervention in age-associated clonal disorders. Citation Format: Shilpita Karmakar, Yang Liu, Efthymios Motakis, Kaustav Sengupta, Travis Roeder, Kristina Mujica, Jennifer Trowbridge, Hideyuki Oguro, Sheng Li. TET2 accelerates clonal hematopoiesis in an age-dependent manner [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4398.

Deep learning-based predictive classification of functional subpopulations of hematopoietic stem cells and multipotent progenitors.

Hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) play a pivotal role in maintaining lifelong hematopoiesis. The distinction between stem cells and other progenitors, as well as the assessment of their functions, has long been a central focus in stem cell research. In recent years, deep learning has emerged as a powerful tool for cell image analysis and classification/prediction. In this study, we explored the feasibility of employing deep learning techniques to differentiate murine HSCs and MPPs based solely on their morphology, as observed through light microscopy (DIC) images. After rigorous training and validation using extensive image datasets, we successfully developed a three-class classifier, referred to as the LSM model, capable of reliably distinguishing long-term HSCs, short-term HSCs, and MPPs. The LSM model extracts intrinsic morphological features unique to different cell types, irrespective of the methods used for cell identification and isolation, such as surface markers or intracellular GFP markers. Furthermore, employing the same deep learning framework, we created a two-class classifier that effectively discriminates between aged HSCs and young HSCs. This discovery is particularly significant as both cell types share identical surface markers yet serve distinct functions. This classifier holds the potential to offer a novel, rapid, and efficient means of assessing the functional states of HSCs, thus obviating the need for time-consuming transplantation experiments. Our study represents the pioneering use of deep learning to differentiate HSCs and MPPs under steady-state conditions. This novel and robust deep learning-based platform will provide a basis for the future development of a new generation stem cell identification and separation system. It may also provide new insight into the molecular mechanisms underlying stem cell self-renewal.

Time-series analysis of hematopoietic stem cells.

This study aimed to investigate the molecular mechanisms underlying the aging of hematopoietic stem cells (HSCs). Gene expression profile GSE32719 was downloaded from the Gene Expression Omnibus database, including 14 young, 5 middle, and 8 old HSCs. Differential expression analysis, short time-series expression miner analysis, and weighted co-expression network analysis were conducted to screen for hub genes whose expression changed over time during HSC aging. Subsequently, functional enrichment and multiple regulatory network analyses of the hub genes were performed. A total of 124 intersecting time-dependent differentially expressed and module genes were obtained, which were considered hub genes whose expression changed over time during HSC aging. Hub genes were significantly enriched in pathways such as the Hippo and AMP-activated protein kinase (AMPK) signaling pathways. Moreover, AP-1 Transcription Factor Subunit (FOS) and sirtuin 1 (SIRT1) had higher degrees in the protein-protein interaction network, were regulated by more transcription factors (TFs), such as Sp1 transcription factor (SP1) and BRCA1 DNA repair-associated (BRCA1), in the TF-mRNA-miRNA network, were associated with more diseases in the disease-gene network, and could be targeted by more drugs in the drug-gene network. Furthermore, SIRT1 was targeted by miR-9-5p in the TF-mRNA-miRNA network. Hub genes such as FOS and SIRT1 and key pathways such as the Hippo and AMPK signaling pathways may play crucial roles in HSC aging. Moreover, FOS and SIRT1 were regulated by SP1 and BRCA1, respectively, during HSC aging. Furthermore, miR-9-5p may modulate HSC aging by targeting SIRT1. Thus, FOS and SIRT1 may be potential therapeutic targets for age-related hematopoietic dysfunction.

Age-related noncanonical TRMT6-TRMT61A signaling impairs hematopoietic stem cells.

Aged hematopoietic stem cells (HSCs) exhibit compromised reconstitution capacity and differentiation bias toward myeloid lineages. However, the molecular mechanism behind HSC aging remains largely unknown. In this study, we observed that RNA N1-methyladenosine-generating methyltransferase TRMT6-TRMT61A complex is increased in aged murine HSCs due to aging-declined CRL4DCAF1-mediated ubiquitination degradation signaling. Unexpectedly, no difference of tRNA N1-methyladenosine methylome is observed between young and aged hematopoietic stem and progenitor cells, suggesting a noncanonical role of the TRMT6-TRMT61A complex in the HSC aging process. Further investigation revealed that enforced TRMT6-TRMT61A impairs HSCs through 3'-tiRNA-Leu-CAG and subsequent RIPK1-RIPK3-MLKL-mediated necroptosis cascade. Deficiency of necroptosis ameliorates the self-renewal capacity of HSCs and counters the physiologically deleterious effect of enforced TRMT6-TRMT61A on HSCs. Together, our work uncovers a nonclassical role for the TRMT6-TRMT61A complex in HSC aging and highlights a therapeutic target.