Longevity Papers

Age-related declines in neuronal bioenergetic levels may limit vesicular trafficking and autophagic clearance of damaged organelles and proteins. Age-related ATP depletion would impact cognition dependent on ionic homeostasis, but limits on proteostasis powered by GTP are less clear. We used neurons isolated from aged 3xTg-AD Alzheimer's model mice and a novel genetically encoded fluorescent GTP sensor (GEVAL) to evaluate live GTP levels in situ. We report an age-dependent reduction in ratiometric measurements of free/bound GTP levels in living hippocampal neurons. Free GTP colocalized in the mitochondria decreased with age accompanied by the accumulation of free GTP-labeled vesicular structures. The energy dependence of autophagy was demonstrated by depletion of GTP with rapamycin stimulation, while bafilomycin inhibition of autophagy raised GTP levels. Twenty-four-hour supplementation of aged neurons with the NAD precursor nicotinamide and the Nrf2 redox modulator EGCG restored GTP levels to youthful levels and mobilized endocytosis and lysosomal consumption for autophagy via the respective GTPases Rab7 and Arl8b. This vesicular mobilization promoted the clearance of intraneuronal Aβ aggregates, improved viability, and lowered protein oxidative nitration in AD model neurons. Our results reveal age- and AD-related neuronal GTP energy deficits that impair autophagy and endocytosis. GTP deficits were remediated by an external NAD precursor together with a Nrf2 redox modulator which suggests a translational path.

Sarcopenia, the age-related loss of muscle strength and mass, contributes to adverse health outcomes in older adults. While exercise mitigates sarcopenia by transiently activating calcium (Ca2+)- and reactive oxygen species (ROS)-dependent signaling pathways that enhance muscle performance and adaptation, these same signals become chronically elevated in aged skeletal muscle and promote functional decline. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a key transducer of both Ca2+ and ROS signals during exercise. Here we show that CaMKII is chronically activated in aged muscles, promoting muscle dysfunction. Muscle-specific expression of a constitutively active CaMKII construct in young mice recapitulates features of aging muscles, including impaired contractility, progressive atrophy, mitochondrial disorganization, formation of tubular aggregates, and an older transcriptional profile characterized by the activation of inflammatory and stress response pathways. Mediation analysis identified altered heme metabolism as a potential mechanism of CaMKII-induced weakness, independent of muscle atrophy. Conversely, partial inhibition of CaMKII in aged muscle improved contractile function and shifted the transcriptome toward a more youthful state without inducing hypertrophy. These findings identify chronic CaMKII activation as a driver of functional and molecular muscle aging and support the concept that CaMKII exemplifies antagonistic pleiotropy, whereby its beneficial roles in promoting muscle performance and adaptation during youth may incur deleterious consequences in aging. We propose that persistent CaMKII activation in aged skeletal muscle reflects unresolved cellular stress and promotes maladaptive remodeling. Enhancing physiological reserve capacity through exercise, in combination with temporally targeted CaMKII inhibition, may help restore adaptive CaMKII signaling dynamics and preserve muscle function in aging.

Mitochondrial heteroplasmy, the co-existence of different mitochondrial genomes within a cell, is linked to aging and disease. Patients with heteroplasmy due to mitochondrial mutations experience multiple organ complications, particularly poor bone health and bone structure defects. However, the mechanisms involved are generally unknown, due largely to the difficulty of manipulating mtDNA in vivo. To overcome this, we leveraged a heteroplasmic mouse model and discovered that mitochondrial heteroplasmy affects a fundamental developmental process. Specifically, the differentiation of osteoclasts, which resorb bone tissue and maintain bone homeostasis. Mechanistically, there was a reduced localization of specifically respiratory complex I subunits in mitochondria in heteroplasmic mice, disrupting ATP production and osteoclast differentiation. In addition, autophagic flux is exhausted, and the autophagy inducer spermidine restores mitochondrial health and rescues osteoclast activity, both in mice and in cells from patients with primary mitochondrial disease. Together, we identify the mechanisms by which mitochondrial heteroplasmy impacts osteoclastogenesis and discover spermidine as a modulator of this process, which presents a potential treatment for human heteroplasmic conditions such as mitochondrial diseases, which are largely untreatable.

Aging poses significant challenges to cardiovascular health necessitating novel therapeutic approaches. This study investigates the potential of the brown adipose tissue (BAT) derived lipokine 12,13-diHOME to mitigate age-induced impairments in cardiovascular function. Analysis of human and rodent plasma signaling lipids reveals a decline in 12,13-diHOME levels with age. Transplantation of BAT or sustained upregulation of 12,13-diHOME effectively preserved cardiac function in aged male and female mice. Bulk RNA-Seq of hearts from aged mice reveals significant increases in pathways involved in ER stress and fibrosis which were partially attenuated by BAT transplantation or sustained upregulation of 12,13-diHOME. Mechanistically, in vivo and in vitro models demonstrate that 12,13-diHOME alleviated ER stress through CaMKII inhibition, particularly in males. These findings underscore 12,13-diHOME as a promising candidate for combating age-related cardiovascular dysfunction, offering insights into potential therapeutic strategies for addressing cardiovascular diseases in aging populations.

Ensuring the identity and optimal aging state of cell products is critical for the efficacy and safety of cell therapies. Despite rapid iterations, there remains an urgent need for robust and easy-to-implement tests to characterize cell products. Here, we present CIAdex (Cell Identification and Aging Index), an analytical framework that utilizes single-cell Fourier-transform infrared (FTIR) spectral fingerprints and machine learning to achieve precise label-free cell identity assessment and aging quantification. CIAdex employs a Feature Extraction Processor to automatically extract FTIR spectral variables corresponding to distinct cellular biomolecular features, enabling reliable distinction of lineage-, donor-, and batch-specific cell populations using linear discriminant analysis. Through application of the XGBoost algorithm, a quantitative aging index (trPDL/trPN) was further generated for tracking cellular aging dynamics along culture expansion. Notably, trPDL/trPN quantitatively represent subtle age-related shifts among different batches and drug-induced senescence or rejuvenation effects, which are unmeasurable by existing methods. Together, our work demonstrates that CIAdex, by simultaneously label-free identity verification and aging quantification of cell populations, offers a transformative approach to interpret single-cell FTIR spectral fingerprints and provides novel metrics for quality control in cell manufacturing with significant potential for optimization and assurance of cell therapies\' safety and efficacy.

Ovarian aging profoundly impacts reproductive health and accelerates the overall aging process, yet the development of effective therapeutic strategies remains a formidable challenge. In this study, we report the rejuvenating effects of HEP14, a natural activator of protein kinase C (PKC) pathway, on aged ovarian function by inducing mitophagy and effectively clearing reactive oxygen species. To ensure controlled and sustained delivery of HEP14 in vivo, we develop HEP14-loaded PLGA microspheres. Transcriptomic analysis reveals a significant overlap between the transcriptional profiles of HEP14-treated aged ovaries and those of adult ovaries, suggesting molecular rejuvenation process closely associated to HEP14-induced mitophagy. Histopathological evaluations further substantiate these findings, showing that HEP14 enhances mitophagy, exhibits antioxidative properties and promotes follicular regeneration. Consequently, ovarian endocrine function in aged mice is substantially restored. Using transmission electron microscopy, confocal microscopy, and western blot analysis alongside pharmocological inhibitors and PKC-specific siRNA, in vitro studies further demonstrate the restorative effect of HEP14 on mitophagy, leading to improved mitochondrial function and subsequent alleviation of oxidative stress in senescent ovarian granulosa cells. This effect is mediated through the activation of the PKC-ERK1/2 pathway, which plays an pivotal role in the action mechanism in HEP14. These discoveries offer new therapeutic hope for ovarian aging.

Gut microbiota exert an evolutionarily conserved influence on ageing, from invertebrates to humans. How do microbes that are physically confined to the gut lumen affect the systemic physiological process of ageing? In female Drosophila, we show that microbiota increase expression of the peptide hormone Tachykinin (Tk), which corresponds to reduced lifespan. Tk is required for microbiota to shorten lifespan, with knockdown rendering flies constitutively long-lived even in the presence of an intact microbiota. This lifespan extension does not come with canonical costs to fecundity or feeding, but impacts on triacylglyceride (TAG) storage suggest adaptive functions in metabolic homeostasis. In flies with defined (gnotobiotic) microbiotas, we show that we can model Tk-dependent effects of microbiota on lifespan and TAG by monoassociation with Acetobacter pomorum. These effects require Tk in the midgut, and the cognate TK receptor TkR99D in neurons, implicating a microbiota-gut-neuron relay. This relay also appears to compromise gut barrier function in aged flies, indicating roles in healthspan as well as lifespan. However, the effect of TkR99D is independent of its reported role in insulin signalling and adipokinetic hormone signalling which, respectively, are canonical regulators of lifespan and TAG metabolism, suggesting a non-canonical role for TkR99D elsewhere in the nervous system. Altogether our results implicate a microbiota-gut-neuron axis in ageing, via a specific bacterium modulating activity of a specific and evolutionarily-conserved hormone.

As aging is the primary risk factor for many chronic diseases, geroscience aims to target aging to delay age-related decline. Here, we identify Cyrene (dihydrolevoglucosenone), a sustainable, biocompatible solvent, as a novel geroprotective compound. Cyrene extends lifespan and healthspan in C. elegans, improving locomotor function and resistance to oxidative, thermal, osmotic, genotoxic, and proteotoxic stress. It also confers protection in neurodegenerative models of Alzheimer\'s, Parkinson\'s, and Huntington\'s disease. Cyrene is effective when delivered during development or early adulthood and requires administration before day 8 to extend longevity. Its benefits are independent of bacterial metabolism and partially independent of the FOXO transcription factor DAF-16. Importantly, Cyrene also extends lifespan and enhances oxidative stress resistance in Drosophila melanogaster, demonstrating cross-species efficacy. These findings identify Cyrene as a novel geroprotective compound that promotes longevity, resilience, and neuroprotection. Conservation across species supports future work to dissect molecular mechanisms and test its potential in mammals.

Reproductive longevity is essential for female fertility and healthy aging; however, the role of stress response, especially stress granule accumulation, in ovarian aging remains elusive and interventions are lacking. Here, we identified deleterious mutations and decreased expression of NCOA7, a stress-response protein related to granulosa cell senescence in women with physiological and pathological ovarian aging. NCOA7 deletion accelerates oxidative stress-related cellular senescence, ovarian aging and fecundity decline in mice. Mechanistically, NCOA7 partitions into the stress granule containing G3BP1-V-ATPase and facilitates autophagic degradation of stress granules to relieve stress. Boosting granulophagy with rapamycin or lipid nanoparticle-based mRNA delivery of NCOA7 accelerates stress granule clearance, alleviating cellular senescence in human granulosa cells and delaying ovarian aging in mice. This study depicts a mechanism for ovarian resilience to stress and provides potential targets for therapeutic strategies to alleviate ovarian aging.

Telomere attrition stands as a fundamental hallmark of cardiovascular aging, driving cellular senescence and dysfunction across endothelial, cardiomyocyte, and vascular smooth muscle compartments. This review systematically examines: (1) molecular mechanisms linking telomere shortening to oxidative stress (NOX2/PRDX1 axis), epigenetic dysregulation (subtelomeric methylation, H3K9me3 loss), and mitochondrial dysfunction; (2) clinical evidence positioning leukocyte telomere length and telomere-associated proteins (eg, TRF2, POT1) as predictive biomarkers for coronary artery disease, heart failure, and hypertension; and (3) emerging therapeutic strategies ranging from telomerase activation (TA-65, GRN510) to senolytic cocktails (dasatinib + quercetin) and CRISPR (regularly interspersed short palindromic reportsclustered regularly interspaced short palindromic repeats)-based editing (6-29% efficiency in Chinese hamster ovary models). The review further addresses methodological challenges in telomere measurement (quantitative polymerase chain reaction (PCR) vs Flow-FISH standardization) and proposes an integrated risk assessment model combining leukocyte telomere length, oxidative markers (AGEs/sRAGE ratio), and epigenetic clocks. Translationally, we discuss tissue-specific delivery systems to mitigate oncogenic risks of telomerase therapies while emphasizing mitochondrial-targeted approaches for telomere stabilization. This synthesis bridges basic telomere science with clinical cardiology, offering a roadmap for personalized vascular rejuvenation strategies.

Genomic instability and loss of proteostasis are two of the primary Hallmarks of Aging. Although these hallmarks are well-defined in the literature, the mechanisms that drive genomic instability and loss of proteostasis as cells age are still largely unknown. Using budding yeast replicative lifespan as a model for aging in actively dividing cells, we identified nuclear proteins that were depleted in the earliest stages of aging. We found that many age-depleted proteins were involved in ribosome biogenesis, specifically in ribosome processing, or in maintenance of chromatin stability. We focused on topoisomerase I (Top1) as a novel age-depleted nuclear protein and found that its depletion in the early stages of aging was not a result of transcriptional changes or changes in protein turnover. Despite the stark depletion of Top1 in early aging, rescue of this age-dependent depletion was actually harmful to replicative lifespan. We found that Top1, when overexpressed, disrupts the stoichiometry of the RENT complex by pulling Sir2 away from the ribosomal DNA (rDNA), a phenotype which is further enhanced when the overexpressed Top1 is catalytically dead. Loss of Sir2 from the rDNA via the overexpression of catalytically dead Top1 decreases RNA Pol II silencing of a reporter gene inside or adjacent to the rDNA, consistent with the lifespan defect. Finally, we found that the catalytic activity of Top1 plays an important role in the establishment of rDNA silencing, raising the possibility that rDNA secondary structure/DNA topology is important for RNA Pol I-dependent spreading of silent chromatin across the rDNA locus.

Aging is a complex process influenced by genetic, environmental, and psychiatric factors. Recent evidence suggests that epigenetic age acceleration (EAA), a biomarker of biological aging, may be linked to psychiatric disorders, yet the causal direction remains unclear. This study employed a bidirectional two-sample Mendelian randomization (MR) analysis to explore the causal relationships between EAA (IEAA, HannumAA, GrimAA, PhenoAA) and ten psychiatric disorders. Genome-wide association study (GWAS) summary statistics from large European ancestry cohorts were used, and sensitivity analyses were conducted to ensure robustness. Forward MR analysis demonstrated that PhenoAge acceleration (PhenoAA) significantly increased the risk of attention-deficit hyperactivity disorder (ADHD) (OR = 1.043, P = 0.004), suggesting that cumulative biological aging may contribute to neurodevelopmental vulnerabilities. Conversely, Hannum age acceleration (HannumAA) was associated with a protective effect against obsessive-compulsive disorder (OCD) (OR = 0.904, P = 0.004). Reverse MR analysis revealed that autism spectrum disorder (ASD) was linked to a decrease in intrinsic epigenetic age acceleration (IEAA) (OR = 0.811, P = 0.027), while major depressive disorder (MDD) significantly increased both HannumAA (OR = 1.318, P = 0.005) and IEAA (OR = 1.226, P = 0.049). These findings suggest that psychiatric conditions may both influence and be influenced by biological aging processes. This study reveals a bidirectional link between psychiatric disorders and biological aging, showing that early-life mental health conditions may accelerate epigenetic aging and increase age-related disease risk. As psychiatric disorders are recognized as aging risk factors, these findings highlight the need for research on aging-targeted interventions in psychiatric populations.

Understanding the impact of different exercise types on skeletal muscle atrophy in older adults is crucial for designing effective strategies to combat age-related muscle loss. This study explores the molecular mechanisms through which resistance exercise (RES) and endurance exercise (END) mitigate skeletal muscle atrophy. By examining microRNA (miRNA) expression profiles from aging skeletal muscle datasets (GSE165632) in the Gene Expression Omnibus (GEO) database, the research aims to uncover exercise-specific miRNA signatures and their associated regulatory pathways. Using the GEO2R analysis tool, researchers identified differentially expressed miRNAs (DEmiRNAs) between RES and END groups. Predicted target genes of these miRNAs were determined through a combination of miRTarBase, micro-T, and TargetScan databases. Functional enrichment analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, were performed via the DAVID database. Transcription factors were predicted using the ChEA3 database, while protein-protein interaction (PPI) networks were constructed with the STRING database to identify hub genes for further functional enrichment studies. The analysis revealed 30 differentially expressed miRNAs in the RES group and 21 in the END group. In the RES group, key pathways such as FoxO signaling, neurotrophic signaling, insulin resistance, and AMPK were regulated by miRNAs like hsa-miR-574-5p, hsa-miR-34a-5p, and hsa-miR-21-5p. These pathways promote protein synthesis and reduce myocyte apoptosis. In the END group, hub genes were linked to FoxO, TGF-β, MAPK, and cGMP-PKG signaling pathways, regulated by miRNAs such as hsa-miR-194-5p, hsa-miR-146a-5p, and hsa-miR-6831-5p, which enhance mitochondrial function and metabolic regulation. Both exercise types shared common regulatory pathways, including MAPK, TGF-β, and PI3K-Akt, which influence genes like SMAD4 and TRAF6 that are essential for myocyte survival and fibrosis suppression. This study sheds light on the unique and overlapping miRNA-driven regulatory mechanisms behind the effects of RES and END on skeletal muscle atrophy in older adults. Resistance exercise primarily boosts protein synthesis and inhibits apoptosis via pathways like AMPK and p53, while endurance exercise enhances mitochondrial function and energy metabolism through cGMP-PKG signaling. Both exercise modalities converge on critical pathways, providing a scientific basis for developing personalized exercise programs to counteract sarcopenia.

Mitochondria are multifunctional organelles that convert the potential energy stored in nutrients and intermediary metabolites into both heat and an electro- chemical proton-motive force. However, how these outputs are synchronized in cells remains an enduring question. In this work, leveraging multiplexed nanodi- amond quantum sensors to monitor both changes in temperature and magnetic field fluctuations in single primary cells obtained from diverse tissues in adult mice, we identified thermomagnetic correlation profiles uncovering a regulatory feedback loop in which the cell draws upon available intracellular iron to main- tain the mitochondrial electrochemical gradient. These profiles reverse in cells derived from a mouse model of Leigh syndrome and raise the intriguing pos- sibility that primary mitochondrial diseases can be understood as disorders of thermomagnetic homeostasis.

The disposable soma theory (DST) posits that organisms prioritize reproductive success over long-term somatic maintenance, resulting in an inevitable decline after reproduction. However, such a basis does not fully explain the human brain's capacity to preserve metabolically costly, plastic, and cognitively essential functions well beyond the reproductive peak. This Perspective challenges the universality of DST by proposing that brain aging follows a selectively resilient trajectory, shaped by post-reproductive adaptive pressures. Rather than depicting brain aging as passive deterioration, this work reinterprets it as an active and dynamic reallocation of energy and resources under systemic decline. Molecular and biochemical adaptations, such as ketone body metabolism, nicotinamide adenine dinucleotide (NAD⁺) salvage, alternative antioxidant defenses, and persistent estrogenic sensitivity, are presented as integrated strategies that ensure the selective preservation of neuronal functions. This article offers a revised theoretical lens that emphasizes adaptation, regional prioritization, and energetic economy across the lifespan, challenging some postulates of the DST.

Aging is a major risk factor for neurodegeneration and is characterized by diverse cellular and molecular hallmarks. To understand the origin of these hallmarks, we studied the effects of aging on the transcriptome, translatome, and proteome in the brain of short-lived killifish. We identified a cascade of events in which aberrant translation pausing led to altered abundance of proteins independently of transcriptional regulation. In particular, aging caused increased ribosome stalling and widespread depletion of proteins enriched in basic amino acids. These findings uncover a potential vulnerable point in the aging brain's biology-the biogenesis of basic DNA and RNA binding proteins. This vulnerability may represent a unifying principle that connects various aging hallmarks, encompassing genome integrity, proteostasis, and the biosynthesis of macromolecules.

The gut microbiota both adapts to, and shapes, the metabolic state of individuals. This bidirectional relationship is mediated via circulating metabolites and gene regulatory networks and interacts with many organs, including by the gut-brain axis. Here, we have processed the cecum from 232 mice from our recent aging colony across age (6-24 months), diet (chow or high fat), and genetics (43 BXD strains) and sequenced their metagenome, metatranscriptome, and cecal transcriptome. We quantify changes in over 300 species caused by interactions between diet, age, and genetic background. Traditional bioinformatics approaches linked particular microbes to observed phenotypes, while newer machine learning models based microbial clusters accurately predicted host outcomes, including individual body weight (AUC = 0.92) and chronological age (AUC = 0.84). This was further enhanced by a compact 10-feature multi-omics model, combining our microbiome data with prior liver expression data to increase chronological age AUC to 0.95. Mechanistically, integrative network analyses identified dozens of significant links between particular bacterial taxa and gene expression, such as a strong negative correlation between host Ido1 expression and short-chain fatty acid (SCFA)-producing Lachnospiraceae, indicating dietary fat can modulate host tryptophan metabolism via microbiota shifts. Moreover, as our study uses inbred mice sampled across time, we have identified signature sets of taxonomies that provide excellent predictive value for future metabolic outcomes driven by metabolic networks connecting the microbiome to the host organism\'s tissues (here, cecum and liver from the same mice). By better understanding the gut-liver axis, we can understand the cellular etiologies of metabolic disease and identify earlier, personalized diagnostic biomarkers attuned to the genetic background and environmental state of the individual.

Idiopathic pulmonary fibrosis (IPF) is a prevalent and deadly age-related disease characterized by chronic, progressive, and irreversible fibrosis. A key effector cell population in the fibroproliferative response is the fibroblasts. Fibroblast cell senescence gradually worsens during aging, and the acquisition of a senescence-associated secretory phenotype (SASP) turns senescent fibroblasts into pro-inflammatory cells. However, the mechanism promoting senescence in IPF, especially at the post-transcriptional level, is poorly understood. We recently discovered that Nudix Hydrolase 21 (NUDT21, also named CFIm25), an RNA-binding protein, plays a critical role in regulating the expression of SASP factors through alternative polyadenylation (APA). APA allows adding poly(A) tail at different sites of 3' UTR and generates transcript isoforms with different 3' UTR lengths. We found that NUDT21 was downregulated in aging and fibrotic lungs, particularly at the fibrotic foci of IPF lungs known to have abundant senescent myofibroblasts and collagens. NUDT21 knockdown in normal lung fibroblasts promoted the 3' UTR shortening of several STAT3 signaling components and enhanced STAT3 phosphorylation and the expression of several SASPs, including interleukins, collagens, and matrix metalloproteinases (MMPs). Moreover, NUDT21 downregulation may be associated with increased fibroblast senescence and abnormal mitochondrial function. Importantly, mice with Nudt21 deletion in Col1a1 expressing cells aggravated bleomycin-induced pulmonary fibrosis. Taking together, our study demonstrated an important role of NUDT21-mediated APA in regulating SASP expression and fibroblast senescence that could contribute to the pathogenesis of IPF.

Glycation crosslinks account for more than 40% of all known advanced glycation end products (AGEs) and are correlated with many age-related diseases. Despite much interest, crosslinking AGEs (xl-AGEs) remain poorly understood, as they have been challenging to discover, prepare, and quantify. Here we describe a peptide platform that is ideally suited for the study of xl-AGEs, which not only facilitates direct comparisons between the prevalence of known xl-AGEs and other AGEs, but also enables the discovery of previously unknown xl-AGEs. In this study, we use this platform to discover the first known Arg-Arg xl-AGEs, a pair of methylglyoxal-derived dihydroxyimidazolidine hemiacetal crosslink, or MIDAL, isomers. We show that MIDAL can become the major AGE, exceeding levels of all other AGEs, for substrates in which two Arg glycation sites are optimally positioned. We further demonstrate that MIDAL is readily and reversibly generated in biocompatible conditions, persisting with a half-life of more than three days. We also demonstrate that MIDAL can form in living mammalian cells, suggesting that it has the potential to be a dynamic, physiologically relevant and functional xl-AGE. This work therefore offers important insights about MIDAL formation and describes a versatile platform to enable the study of xl-AGEs under a variety of conditions. We expect that it will be highly useful for further discovery of biologically relevant glycation crosslinks that are yet to be identified.

Ubiquitin (Ub), a central regulator of protein turnover, can be phosphorylated by PINK1 (PTEN-induced putative kinase 1) to generate S65-phosphorylated ubiquitin (pUb). Elevated pUb levels have been observed in aged human brains and in Parkinson's disease, but the mechanistic link between pUb elevation and neurodegeneration remains unclear. Here, we demonstrate that pUb elevation is a common feature under neurodegenerative conditions, including Alzheimer's disease, aging, and ischemic injury. We show that impaired proteasomal activity leads to the accumulation of sPINK1, the cytosolic form of PINK1 that is normally proteasome-degraded rapidly. This accumulation increases ubiquitin phosphorylation, which then inhibits ubiquitin-dependent proteasomal activity by interfering with both ubiquitin chain elongation and proteasome-substrate interactions. Specific expression of sPINK1 in mouse hippocampal neurons induced progressive pUb accumulation, accompanied by protein aggregation, proteostasis disruption, neuronal injury, neuroinflammation, and cognitive decline. Conversely, Pink1 knockout mitigated protein aggregation in both mouse brains and HEK293 cells. Furthermore, the detrimental effects of sPINK1 could be counteracted by co-expressing Ub/S65A phospho-null mutant but exacerbated by over-expressing Ub/S65E phospho-mimic mutant. Together, these findings reveal that pUb elevation, triggered by reduced proteasomal activity, inhibits proteasomal activity and forms a feedforward loop that drives progressive neurodegeneration.

Aging is associated with metabolic decline in the brain, increasing susceptibility to neurodegenerative diseases. While exercise is a well-established strategy to counteract these changes, no study has directly compared the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on cortical and hippocampal energy metabolism-key regulators of brain plasticity in aging. To address this gap, we investigated how 4-week MICT and HIIT protocols, structured according to the lactate threshold, affect endurance performance and brain metabolic markers in older Wistar rats. Both training modalities improved endurance, with HIIT demonstrating superior gains in maximal performance. However, molecular analyses revealed that MICT induced more extensive metabolic and angiogenic adaptations in the cortex and hippocampus, including the upregulation of key regulators of energy metabolism and vascularization. RNA sequencing confirmed broader transcriptomic changes following MICT, implicating pathways associated with neurogenesis, metabolic homeostasis, and cellular plasticity. While HIIT provided a time-efficient means of improving cardiovascular endurance and mitochondrial activity through different molecular pathways when compared to MICT, its impact on brain metabolism was more limited. These findings suggest that MICT is the preferred regimen for enhancing cerebral metabolic function and neurovascular adaptation, while HIIT serves as a complementary strategy to involve other brain metabolism-associated pathways and maximize aerobic fitness. A direct comparison of these modalities, as presented here, is essential for refining exercise prescriptions to support brain health in aging.

Retinal degenerative diseases, such as age-related macular degeneration (AMD), retinitis pigmentosa, and glaucoma, have been linked to mitochondrial dysfunction. However, the impact of mitochondrial DNA (mtDNA) mutation accumulation in the context of these retinopathies has yet to be thoroughly explored. Our previous studies focused on the retinal phenotype observed in the PolgD257A mutator mice (D257A), revealing the effects of aging and mtDNA mutation accumulation in the retina. We have reported that this model exhibited significant morphological and functional deficits in the retina by 6 months of age, with notable alterations in the retinal pigment epithelium (RPE) occurring as early as 3 months, including changes in the cristae density and reduction in length of mitochondria. This study investigated how mtDNA mutations affect the metabolic interaction between the retina and RPE in young (3 months) and old (12 months) wild-type (WT) and D257A mice. We assessed cellular energy production using freshly dissected retina samples from both groups through Seahorse analysis, immunofluorescence, and Western blot experiments. The analysis of aged D257A retina punches revealed significantly reduced basal and maximal mitochondrial respiration, along with increased mitochondrial reserve capacity compared to WT. However, glycolytic flux, measured as a function of extracellular acidification rate (ECAR), did not differ between WT and D257A mice. Both D257A retina and RPE exhibited decreased expression of essential electron transport proteins involved in oxidative phosphorylation. Additionally, we observed a reduction in the expression of glucose transporter 1 (GLUT-1) and lactate transporter (MCT1) at the apical surface of the RPE. Enzymes associated with glycolysis, including hexokinase II and lactate dehydrogenase A, were significantly lower in the aged D257A retina, while hexokinase I and pyruvate kinase 2 were upregulated in the RPE. These findings indicate that the accumulation of mtDNA mutations leads to impaired metabolism in both the retina and RPE. Furthermore, it suggests that glucose from the choroidal blood supply is being utilized by the RPE rather than transported to the neural retina. Mitochondrial dysfunction in RPE promotes a glycolytic state in these cells, leading to reduced availability of metabolites and, consequently, diminished overall retinal function. These results are essential for advancing our understanding of the mechanisms underlying retinal degeneration and provide a new perspective on the role of mtDNA mutations in these diseases.

Cellular senescence, marked by irreversible cell cycle arrest and senescence-associated secretory phenotype, contributes to aging and cancer recurrence. While chemotherapy can induce senescence in cancer cells, these therapy-induced senescent cells often resist apoptosis and promote tumor recurrence. The nuclear interaction between FOXO4 and p53 is crucial for senescent cell survival. Using NMR spectroscopy, we identified that hydrophobic interactions in the p53 transactivation domain play a key role in FOXO4 forkhead domain binding. Based on this structural information, we designed an optimized peptide inhibitor with reduced negative charges and incorporated a cationic cell-penetrating peptide for enhanced cellular delivery (CPP-CAND). CPP-CAND exhibited high selectivity for senescent cells, effectively disrupting nuclear FOXO4-p53 foci and inducing caspase-dependent apoptosis. Notably, it showed cytotoxicity against senescent cancer cells induced by different chemotherapeutic agents including doxorubicin and cisplatin. With its enhanced selectivity, l-amino acid composition, and shorter length, CPP-CAND represents a promising therapeutic candidate for targeting therapy-induced senescent cancer cells.

Clonal hematopoiesis (CH) has emerged as a common age-related phenomenon and a central concept linking somatic mutations in hematopoietic stem cells to both malignant and non-malignant diseases. While initially recognized in the context of hematologic neoplasms, CH is now known to contribute to increased all-cause mortality, particularly through heightened risk of cardiovascular and inflammatory diseases. Frequent mutations in genes such as DNMT3A, TET2, and ASXL1 alter epigenetic regulation and immune signaling, thereby promoting clonal expansion and systemic consequences. Longitudinal studies have illuminated the dynamics of clonal growth and revealed how germline variants influence somatic selection. VEXAS syndrome, driven by UBA1-mutated CH, exemplifies the broader clinical reach of clonal expansion beyond malignancy. CH occupies an intermediate biological state with far-reaching implications. In this Progress in Hematology series, contributors explore the natural history, genetic underpinnings, and inflammatory manifestations of CH, offering insights into its role as both a biomarker and a potential therapeutic target in aging populations.

Identifying the set of genes that regulate baseline healthy aging - aging that is not confounded by illness - is critical to understating aging biology. Machine learning-based age-estimators (such as epigenetic clocks) offer a robust method for capturing biomarkers that strongly correlate with age. In principle, we can use these estimators to find novel targets for aging research, which can then be used for developing drugs that can extend the healthspan. However, methylation-based clocks do not provide direct mechanistic insight into aging, limiting their utility for drug discovery. Here, we describe a method for building tissue-specific bulk RNA-seq-based age-estimators that can be used to identify the ageprint. The ageprint is a set of genes that drive baseline healthy aging in a tissue-specific, developmentally-linked fashion. Using our age estimator, SkeletAge, we narrowed down the ageprint of human skeletal muscles to 128 genes, of which 26 genes have never been studied in the context of aging or aging-associated phenotypes. The ageprint of skeletal muscles can be linked to known phenotypes of skeletal muscle aging and development, which further supports our hypothesis that the ageprint genes drive (healthy) aging along the growth-development-aging axis, which is separate from (biological) aging that takes place due to illness or stochastic damage. Lastly, we show that using our method, we can find druggable targets for aging research and use the ageprint to accurately assess the effect of therapeutic interventions, which can further accelerate the discovery of longevity-enhancing drugs.