Longevity Papers

An increase in the number of senescent cells with advancing age is a major predisposing factor for aging-related osteoarthritis (OA). However, effective intervention strategies targeting cellular senescence have yet to be developed. Increasing evidence suggests that rising epigenetic entropy, specifically the detachment of heterochromatin from the nuclear envelope, is a driver of cellular senescence.

Dietary protein is a key regulator of metabolic health in humans and rodents. Many of the benefits of protein restriction are mediated by reduced intake of dietary branched-chain amino acids (leucine, valine and isoleucine) and restriction of the branched-chain amino acids is sufficient to extend healthspan and lifespan in mice. Here we find that valine restriction (Val-R) improves metabolic health in C57BL/6J mice, promotes leanness and glycemic control across ages, and reduces frailty, cancer prevalence and senescent cell burden in both sexes while increasing median male lifespan by 23%. Assessing gene relationships across tissues, we identified a liver gene module enriched in mitochondrial pathways and increased mitochondrial respiration in Val-R-fed male mice. Our results demonstrate that Val-R improves multiple aspects of healthspan in mice of both sexes, extends lifespan in male mice and suggests that interventions that mimic Val-R may have translational potential for aging and age-related diseases.

Mitochondrial reactive oxygen species (mtROS) have been implicated in aging and disease for decades and are typically viewed as a unitary, non-specific oxidative burden on cells and tissues. However, recent studies have identified at least eleven individual sources of mitochondrial ROS (ISOMRs) and revealed that ISOMRs have distinct, dynamic, and often reversible roles in diverse physiological and pathological processes, including neurodegenerative diseases, immune and metabolic dysregulation, and ischemia-reperfusion injury. This review describes the upstream molecular events that control ISOMR activity, recently developed tools for studying mtROS in general and ISOMRs more specifically, and the evolving perspectives on ISOMR roles in context-specific cell signaling. Future studies to define predictive principles of ISOMR regulation are necessary to open frontiers of redox biology and identify therapeutic strategies for selective modulation of ISOMR-dependent mechanisms in aging and disease.

Satellite cells (SCs) are essential for skeletal muscle regeneration, but their function declines with aging, often associated with increased pro-apoptotic signaling. This study investigated the impact of in vitro serum starvation-as a model of acute microenvironmental and nutrient stress-on the apoptosis and differentiation potential of human SCs from young and aged donors. SCs were isolated from the Vastus Lateralis of young and aged subjects and cultured in serum-free medium for up to 72 h. We assessed apoptosis through Annexin V/PI staining, TUNEL assays, and caspase activity measurements, while transcriptional profiles were analyzed via RT-PCR. Aged SCs displayed a significantly higher susceptibility to stress-induced apoptosis compared to young controls, marked by the early upregulation of CASP9 and FOXO1. While typical nucleosomal DNA fragmentation was absent, we observed the activation of caspase-3 after 72 h of starvation. In aged cells, activated caspase-3 co-localized with myogenin and extranuclear DNA at sites of nuclear remodeling. Notably, treatment with a pan-caspase inhibitor (z-VAD-fmk) prevented the formation of micronuclei and myotubes, further highlighting a non-apoptotic role for these enzymes. Aged SCs also showed a distinct cell cycle profile characterized by an enlarged G0/G1 phase and altered expression of CDK and CCNB1 genes. Our findings suggest that in human aged SCs, caspase enzymes serve a dual role: mediating a heightened stress response and facilitating the nuclear remodeling necessary for myogenic differentiation. These results clarify how intrinsic aging shapes the response of muscle stem cells under severe environmental and metabolic resource deprivation.

The age-related decline in oocyte nicotinamide adenine dinucleotide (NAD) is associated with reduced developmental potential and female infertility. Despite the extraordinary longevity of the female germline, the mechanism for maintaining oocyte NAD remains unresolved. Here, we used stable isotope tracing to identify a new mechanism for shared, intercellular NAD biosynthesis, whereby somatic-germline metabolic coupling between the oocyte and its surrounding cumulus cells is critical to maintain oocyte NAD homeostasis. We show that this coupling deteriorates with reproductive aging, identifying altered NAD metabolism in cumulus cells from mice and women of advancing reproductive age. This cumulus-oocyte metabolic coupling of NAD biosynthesis contributes to protection against the age-related increases in oocyte reactive oxygen species (ROS). In intact complexes, restoring NAD through supplementation with the precursor nicotinamide mononucleotide (NMN) increased glutathione, reduced ROS and improved mitochondrial membrane potential in oocytes from aged mice and in oocytes exposed to oxidative insult. Importantly, the ability of NMN to resolve elevated ROS depends on the presence of cumulus cells. Together, this new model of somatic-germline metabolic coupling of NAD biosynthesis places an age-related deterioration in cumulus cell-mediated metabolic support as a key driver of impaired oocyte NAD levels and redox dysregulation with aging.

Hematopoietic stem cell (HSC) aging is often described as a gradual loss of stem cell fitness that culminates in impaired blood production, immune dysfunction, and increased susceptibility to hematologic disease. However, recent work suggests that this view is too simple. Rather than a uniform decline, aging appears to remodel the HSC compartment into metabolically and functionally distinct states, including maladaptive trajectories as well as surprisingly resilient subsets. In this review, we argue that HSC aging is best understood through the interplay of mitochondrial regulation, metabolic uncoupling, and niche-derived stress, with particular emphasis on how recent findings revise several longstanding assumptions in the field (Box 1).

This study examines the biological and clinical relevance of NAD⁺ supplementation using a combined review and mathematical modelling approach. NAD⁺ plays a central role in cellular energy metabolism, redox balance, and signaling pathways linked to aging, neurodegeneration, and metabolic health. Current evidence shows that oral NAD⁺ precursors such as nicotinamide riboside and nicotinamide mononucleotide can increase circulating NAD⁺ levels, although their clinical benefits remain variable and context-dependent. Intravenous NAD⁺ administration is less well characterized and lacks robust clinical validation. The modelling framework presented here highlights that NAD⁺ responses are nonlinear and influenced by factors such as dose, age, metabolic state, and route of administration. Rather than following a simple dose-response relationship, NAD⁺ supplementation appears to operate within a complex regulatory system involving feedback mechanisms and biological saturation. Overall, these findings emphasize the need for cautious interpretation of current data and for well-designed clinical studies to define effective and safe therapeutic strategies.

Apolipoprotein E4 (APOE4) is the strongest genetic risk factor for late-onset Alzheimer's disease and promotes neuronal dysfunction through incompletely understood mechanisms. Here, we integrated transcriptomic, translatomic, and proteomic profiling of isogenic APOE3 and APOE4 human iPSC-derived neurons and found that APOE4 fundamentally impairs neuronal proteome renewal. Although transcriptional changes were modest, APOE4 disrupted ribosome occupancy, altered translational dynamics, and uncoupled protein abundance from transcript levels. Proteome-wide turnover measurements revealed a global extension of protein half-lives and widespread accumulation of long-lived proteins. Functional proteomic analyses demonstrated concurrent lysosomal and proteasomal impairments associated with reduced proteasome activity and increased association of APOE with neuronal proteasomes. Longitudinal proteomics further showed that protein accumulation emerges during neuronal maturation and precedes a senescence-like cellular stress state. Together, these findings identify impaired proteome renewal as a central mechanism underlying neuronal vulnerability to APOE4 and establish defective proteostasis as an early pathogenic event in Alzheimer's disease.

Sickle cell disease (SCD) is a blood disorder affecting millions worldwide. Emerging evidence reveals that SCD pathophysiology increases the risk of myeloid malignancies and hematopoietic stem cell (HSC) dysfunction, likely because of chronic stress on bone marrow. To investigate this further, we interrogated bone marrow hematopoietic stem and progenitor cells (HSPCs) from mice and individuals with SCD and observed molecular signatures of chronic cellular stress including oxidative stress, DNA damage, and hallmarks of senescence. Consistent with these findings, SCD HSPCs displayed transcriptomic dysregulation of senescence-associated molecular programs and diminished mitogen response with prolonged cell cycle kinetics during time-lapse live cell imaging. SCD mice displayed a marked loss of immunophenotypic bone marrow HSPCs by flow cytometry and functional blood repopulating HSPCs in transplantation studies, whereas human SCD bone marrow HSPCs exhibited poor ex vivo hematopoietic colony-forming ability, and these phenotypes were reversed after senescence-targeting therapy with either ABT-263 (navitoclax) or the combination of dasatinib and quercetin. Thus, treatment with senescence-targeting therapy improves bone marrow HSPC function in vivo in mice and ex vivo in cells from individuals with SCD and could represent a possible strategy to improve HSPC health, promote manufacture of high-quality bespoke clinical products, and potentially enhance the safety of potentially curative gene therapies using autologous HSPCs from individuals with SCD.

Reproductive aging in vertebrates is commonly interpreted as a gradual decline; however, whether aging of the male gonad proceeds linearly or is characterized by periods of accelerated remodeling remains unclear. The turquoise killifish (Nothobranchius furzeri), a short-lived vertebrate, enables lifespan-wide resolution of both rapid germline establishment and subsequent aging within months.

Aging is characterized by a progressive decline in cellular and tissue function, shaped in part by disruptions in communication between the extracellular matrix (ECM) and intracellular signaling networks. The cell surface receptor CD44 functions as a molecular hub, integrating signals from a remodeled ECM to regulate core aging programs including senescence, inflammation, and metabolic balance. This review synthesizes evidence that CD44, through its structural domains, isoform diversity, and proteolytic processing, integrates extracellular cues to modulate key pathways such as STAT3, NF-κB, and the class III PI3K complex. Mechanistically, HA-fragment engagement of CD44 activates the CD44-STAT3 axis in vascular tissue, suppressing autophagic flux and promoting endothelial senescence. Concurrently, ECM-derived ligand binding to CD44 drives NF-κB signaling that amplifies chronic inflammation in a tissue and context-dependent manner, contributing to inflammaging. Functional outcomes are context-dependent, shaped by isoform switching and γ-secretase-mediated release of CD44-ICD, which may drive degeneration or support repair and proteostasis. Emerging single-cell and spatial transcriptomics reveal spatiotemporal CD44 dysregulation across vasculature, brain, adipose tissue, kidney, and liver. This review establishes CD44 as a mechanistic link connecting ECM remodeling to nuclear responses in aging and outlines therapeutic strategies including ligand competition, antibody blockade, and γ-secretase modulation to mitigate age-related pathology and extend health span. These insights provide a coherent framework for understanding aging biology and guiding future translational interventions targeting CD44 signaling pathways effectively.

Endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) are now recognized as integral components of the proteostasis network that preserves cellular and tissue function across the lifespan. With aging, increasing oxidative load, metabolic imbalance, and Ca

Cells use multiple protein quality control (PQC) mechanisms to counteract the toxic effects of protein aggregation caused by cellular stress, ageing or disease. While it is known that PQC mechanisms differ between cellular compartments, studying such differences has remained challenging. Previously, we developed an assay to study cytosolic PQC using aggregates formed through chemically-induced dimerization (termed PIMs, particles induced by multimerization). Here, we introduce nuclear PIMs as a tool to study nuclear quality control. Using high-resolution and high-throughput imaging, we show that nuclear aggregate removal depends on the proteasome and the unfoldase VCP, but not on Hsp70. Strikingly, following dissolution many PIM subunits were exported to the cytosol via exportin-1-dependent shuttling, indicating that disaggregation and resolubilization dominated over degradation. Proteasomal disaggregation was confirmed using live-cell turnover experiments. Together, these findings reveal a mechanism in which the proteasome and VCP disaggregate, rather than degrade, nuclear protein aggregates, with the resulting subunits subsequently cleared via cytosolic aggrephagy.

Epigenetic clocks derived from DNA methylation robustly predict biological aging, health, and mortality, yet differ substantially in their predictive profiles. The biological processes underlying these differences remain poorly understood. Using data from 3227 participants in the U.S. Health and Retirement Study, with contemporaneous DNA methylation and RNA-sequencing, we examined the five most widely used epigenetic clocks (Horvath, Hannum, PhenoAge, GrimAge, and DunedinPACE). We conducted differential gene expression analyses to identify clock-specific gene expression levels and enriched biological pathways, to reveal substantial heterogeneity in the molecular processes captured by each clock. We further derived transcriptomic aging gene scores (TAGS) from differentially expressed genes associated with each age acceleration clock, and evaluated their associations with aging-related phenotypes. TAGS complemented DNAm clocks, and in several cases, showed stronger associations with age-related morbidities and mortality. Findings unveiled more unique than common biological processes underlying clocks, illuminating their internal mechanisms, and advancing their interpretability for aging research and clinical applications.

Aging is a biologically tractable process. Telomerase reverse transcriptase (TERT) has emerged as an upstream regulator coordinating several hallmarks of aging across preclinical models. Beyond maintaining telomeres, TERT influences mitochondrial health, epigenetic regulation, inflammation and stem cell function. Multiple translational strategies are being explored to modulate TERT. In mice and human cell models, restoration of physiological-range TERT expression characteristic of younger cells, or related telomere-focused interventions, has been associated with improvements in selected age-related phenotypes without a detectable increase in cancer. Simultaneously, human genetics links common variation in the TERT locus to increased risk of several cancers, underscoring the need for careful mechanistic and long-term safety evaluations. Together, mounting evidence indicates that TERT occupies an important position in aging biology with the potential to affect healthspan. This Perspective reviews current evidence for TERT's canonical and noncanonical roles and outlines a cautious therapeutic framework for evaluating TERT-directed geroprotective strategies.