Aging can be experimentally induced in Hydra oligactis, making it an exception among the "immortal" cnidarian genus Hydra. In response to cold temperatures, H. oligactis polyps switch from asexual to "emergency" sexual reproduction and eventually age and die. We used GC-MS-based metabolite profiling to characterize cold-induced (CI) metabolic reprogramming during concurrent sexual differentiation and aging in H. oligactis. Metabolites in four clusters either decreased or increased progressively until week 8, when animals were severely aged, whereas others peaked at sexual maturity after 4-6 weeks. At week 4, signatures of failing cytoprotection and neurotransmitter function appeared in both sexes, including a drastic reduction of taurine, whose deficiency is a known driver of aging in other organisms. Taurine supplementation partly reversed interstitial stem cell loss during the first 2 weeks of cold induction and subsequent sexual differentiation. Metabolites in the NAD+ synthesis and salvage pathways, such as picolinate and niacin, also declined. Changes in pyruvate and TCA cycle intermediates indicated increased energy demands associated with both gametogenesis and aging. Urate, the final oxidation product of purine metabolism, showed the highest fold-change, peaking at sexual maturity in both sexes and remaining elevated. The abundance of most purine and pyrimidine bases also increased, in line with nucleotide cleavage by apoptosis, as part of gametogenesis and aging. Sexual maturity was clearly reflected by high levels of polyamines, such as putrescine, cadaverine, and 3-hydroxybutyrate, required for spermatogenesis. Our study reveals metabolic processes related to gametogenesis and aging and highlights differences between female and male metabolism.

Cells rely on lysosomes and autophagy to maintain homeostasis under fluctuating environmental and metabolic conditions. However, how these degradative systems are dynamically coordinated across stress, senescence, and aging remains incompletely understood. Transcription factor EB (TFEB), a member of the microphthalmia/transcription factor E (MiT/TFE) family, has emerged as a key regulator of lysosomal biogenesis and autophagy by controlling the coordinated lysosomal expression and regulation (CLEAR) gene network, integrating nutrient sensing, mitochondrial status, Ca2+, redox signaling, and mechanistic target of rapamycin complex 1 (mTORC1) activity. While TFEB activation promotes lysosomal and metabolic adaptation during acute stress, accumulating evidence indicates that its activity is tightly constrained in time and magnitude, and that altered TFEB dynamics critically shape cellular fate decisions. Here, we synthesize current findings showing that transient TFEB activation supports stress resilience and recovery. In contrast, persistent, insufficient, or dysregulated TFEB signaling contributes to divergent senescence trajectories and age-associated decline in proteostasis. We further discuss how defects in TFEB regulation underlie impaired autophagy–lysosome function during aging across tissues. Notably, both insufficient and excessive TFEB activity can be maladaptive. Together, this framework positions TFEB as a dynamically regulated node linking stress adaptation, senescence progression, and aging, and highlights the need for context- and tissue-specific strategies aimed at restoring TFEB responsiveness rather than constitutively enhancing its activity.

The alpine plant Cicerbita alpina (L.) Wallr., when grown as a sprout, is known as a bitter-tasting culinary delicacy. Recently it has also been reported to have anthelmintic activity, prompting further investigation into its mechanism of action. Liquid–liquid fractions were prepared from a methanolic extract of the aerial parts and were submitted in parallel to embryo development (ED), worm motility (WMT), and cytotoxicity assays for anthelmintic and toxicity evaluations. The anthelminthic assays revealed the more polar fractions to be most active against Ascaridia galli embryos (BuOH | 68% ED | c = 500 µg/ml and EtOAc | 65% ED | c = 500 µg/ml) and Caenorhabditis elegans adult worms (BuOH | 49% WMT | c = 150 µg/ml and EtOAc | 74% WMT | c = 150 µg/ml) suggesting the fraction’s constituents possess dual anthelmintic activity against multiple life-cycle stages (i.e., eggs, worms) of helminths. Additionally, the BuOH fraction was non-cytotoxic to human cell-lines. Subsequent FCC and SEC derived subfractions were submitted to the anthelmintic assay workflow and the enriched subfractions B1 and E3.8, phytochemically assigned as 11-β,13-dihydrolactucin and luteolin, demonstrated bioactivity against the embryo phenotype (B1 | 58% ED | c = 1.8 µM and E3.8 | 46% ED | c = 1.7 µM) within range of the flubendazole control. Furthermore, luteolin was found to inhibit C. elegans egg hatching (luteolin | 65% EH | c = 10 µM | t = 10 h) within the range of the control albendazole. Both identified anthelmintic phytochemicals were found to affect tubulin polymerisation at a concentration of c = 50 µM. Together with in silico virtual screening studies, these results suggest microtubule stabilisation as a possible anthelmintic target and mechanism of action. This work effectively advocates the consideration of C. alpina extracts and fractions for the development of herbal therapeutics against parasitic helminths.

Cells experience oxidative stress and widespread cellular damage during stress-induced premature senescence (SIPS). Senescent cells show an increase in lysosomal content, which may contribute to mitigating cellular damage by promoting autophagy. This study investigates the dynamics of lysosomal quality control in human dermal fibroblasts (HDF), specifically examining lysosomal signaling pathways during oxidative stress-induced SIPS. Our results reveal distinct signaling responses between the initial stress phase and the ensuing senescent phenotype. During the stress phase, treatment with tBHP, which undermines the antioxidant response, leads to elevated reactive oxygen species (ROS) and lysosomal damage. ROS accumulation activates AMP-activated protein kinase (AMPK) and inhibits Akt, which correlates with the suppression of mammalian target of rapamycin (mTOR). Inactivation of mTOR during this phase aligns with the activation of transcription factor EB (TFEB), a key regulator of autophagy and lysosomal biogenesis. TFEB knockdown under stress increased apoptosis, highlighting the protective role of TFEB in the stress response. As cells transition to senescence, TFEB activity, required for the autophagic damage repair, becomes less critical. The decrease in ROS levels leads to the normalization of AMPK and Akt signaling, accompanied by the reactivation of mTOR. This reactivation of mTOR, which is critical for establishing the senescent state, is observed alongside the inactivation of TFEB. Consequently, as damage decreases, TFEB activity decreases. Our results suggest a dynamic interplay between TFEB and mTOR, highlighting a critical role of TFEB in ensuring cellular survival during SIPS induction but becoming dispensable once senescence is established.

Extrinsic skin aging is driven by environmental factors, including ultraviolet (UV) radiation and air pollution. While melanocytes serve as key protectors against UV-induced damage, their role in aging, particularly through the process of senescence, remains underexplored. Here, we exposed human neonatal melanocytes and ex vivo skin explants to UV (UVA + UVB), urban particulate matter (UPM), and their combination (UV + UPM) to assess the effects on melanocyte function and skin aging. We demonstrate that combined UV + UPM exposure triggers oxidative stress, mitochondrial and DNA damage, senescence, apoptosis, and modulation of melanogenesis in human neonatal melanocytes. In addition, skin explants subjected to the same treatments showed hallmark features of aging, including epidermal thinning, barrier disruption, fibrosis, and altered pigmentation. These findings highlight that melanocytes respond to environmental stress through multiple interconnected mechanisms, potentially affecting both cell survival and pigmentary function. Our model offers a useful platform to study how environmental stressors affect melanocyte function and skin biology, potentially supporting the development of future strategies targeting pigmentation disorders and environmentally driven skin aging.

This review consolidates a decade of research on fumarylacetoacetate hydrolase domain containing protein 1 (FAHD1), a mitochondrial oxaloacetate tautomerase and decarboxylase with profound implications in cellular metabolism. Despite its critical role as a regulator in mitochondrial metabolism, FAHD1 has remained an often-overlooked enzyme in broader discussions of mitochondrial function. After more than 12 years of research, it is increasingly clear that FAHD1's contributions to cellular metabolism, oxidative stress regulation, and disease processes such as cancer and aging warrant recognition in both textbooks and comprehensive reviews. The review delves into the broader implications of FAHD1 in mitochondrial function, emphasizing its roles in mitigating reactive oxygen species (ROS) levels and regulating complex II activity, particularly in cancer cells. This enzyme's significance is further highlighted in the context of aging, where FAHD1's activity has been shown to influence cellular senescence, mitochondrial quality control, and the aging process. Moreover, FAHD1's involvement in glutamine metabolism and its impact on cancer cell proliferation, particularly in aggressive breast cancer subtypes, underscores its potential as a therapeutic target. In addition to providing a comprehensive account of FAHD1's biochemical properties and structural insights, the review integrates emerging hypotheses regarding its role in metabolic reprogramming, immune regulation, and mitochondrial dynamics. By establishing a detailed understanding of FAHD1's physiological roles and therapeutic potential, this work advocates for FAHD1's recognition in foundational texts and resources, marking a pivotal step in its integration into mainstream metabolic research and clinical applications in treating metabolic disorders, cancer, and age-related diseases.

Metallothioneins (MTs) are a family of mostly low-molecular weight, cysteine-rich proteins capable of specific metal-ion binding that are involved in metal detoxification and homeostasis, as well as in stress response. In contrast to most other animal species which possess two-domain (bidominial) MTs, some gastropod species have evolved Cd2+-selective multidomain MTs (md-MTs) consisting of several concatenated β3 domains and a single C-terminal β1 domain. Each domain contains three-metal ion clusters and binds three metal ions. The terrestrial snail Alinda biplicata possesses, among other MT isoforms, an md-MT with nine β3 domains and a C-terminal β1 domain (termed 10md-MT), capable of binding up to 30 Cd2+ ions per protein molecule. In the present study, the Alinda biplicata 10md-MT gene and a truncated version consisting of one β3 domain and a single C-terminal β1 domain (2d-MT) were introduced into a Caenorhabditis elegans knock-out strain lacking a native MT gene (mtl-1). The two snail MT constructs consistently increased Cd2+ resistance, and partially improved morphological, life history and physiological fitness traits in the nematode model host Caenorhabditis elegans. This highlights how the engineering of transgenic Caenorhabditis elegans strains expressing snail MTs provides an enhancement of the innate metal detoxification mechanism and in doing so provides a platform for enhanced mechanistic toxicology.

Cellular senescence, a state of irreversible growth arrest, is implicated in various age-related pathologies, including skin aging. In this study, we investigated the role of CLCA2, a calcium-activated chloride channel accessory protein, in cellular senescence and its implications for skin aging. Utilizing UVB and Nutlin3a-induced senescence models, we observed the upregulation of CLCA2 at both transcriptomic and proteomic levels, suggesting its involvement in senescence pathways. Further analysis revealed that the depletion of CLCA2 led to accelerated senescence onset, characterized by classic senescence markers and a unique secretome profile. In 3D skin equivalent models, SEs constructed with CLCA2 knockdown fibroblasts exhibited features reminiscent of aged skin, underscoring the importance of CLCA2 in maintaining skin homeostasis. Our findings highlight CLCA2 as a novel regulator of cellular senescence and its potential implications for skin aging mechanisms.

Cellular senescence is a cell fate triggered in response to stress and is characterized by stable cell-cycle arrest and a hypersecretory state. It has diverse biological roles, ranging from tissue repair to chronic disease. The development of new tools to study senescence in vivo has paved the way for uncovering its physiological and pathological roles and testing senescent cells as a therapeutic target. However, the lack of specific and broadly applicable markers makes it difficult to identify and characterize senescent cells in tissues and living organisms. To address this, we provide practical guidelines called “minimum information for cellular senescence experimentation in vivo” (MICSE). It presents an overview of senescence markers in rodent tissues, transgenic models, non-mammalian systems, human tissues, and tumors and their use in the identification and specification of senescent cells. These guidelines provide a uniform, state-of-the-art, and accessible toolset to improve our understanding of cellular senescence in vivo.

Skin aging is the result of two types of aging, "intrinsic aging" an inevitable consequence of physiologic and genetically determined changes and "extrinsic aging," which is dependent on external factors such as exposure to sunlight, smoking, and dietary habits. UVB causes skin injury through the generation of free radicals and other oxidative byproducts, also contributing to DNA damage. Appearance and accumulation of senescent cells in the skin are considered one of the hallmarks of aging in this tissue. Mitochondria play an important role for the development of cellular senescence, in particular stress-induced senescence of human cells. However, many aspects of mitochondrial physiology relevant to cellular senescence and extrinsic skin aging remain to be unraveled. Here, we demonstrate that mitochondria damaged by UVB irradiation of human dermal fibroblasts (HDF) are eliminated by NIX-dependent mitophagy and that this process is important for cell survival under these conditions. Additionally, UVB-irradiation of human dermal fibroblasts (HDF) induces the shedding of extracellular vesicles (EVs), and this process is significantly enhanced in UVB-irradiated NIX-depleted cells. Our findings establish NIX as the main mitophagy receptor in the process of UVB-induced senescence and suggest the release of EVs as an alternative mechanism of mitochondrial quality control in HDF.

Skin aging is a complex process influenced by intrinsic factors and environmental stressors, including ultraviolet (UV) radiation and air pollution, among others. In this study, we investigated the effects of UVA and UVB radiation, combined with urban particulate matter (UPM), on human dermal fibroblasts (HDF). We show here that treatment of HDF with a subcytotoxic dose of UVA/UVB results in a series of events leading to mitochondrial dysfunction, increased ROS levels, and DNA damage. These effects are known to trigger either cellular senescence or cell death, depending on the cells' ability to clear damage by activating autophagy. Whereas UPM treatment in isolation did not affect proliferation or survival of HDF, of note, simultaneous UPM treatment of UV-irradiated cells selectively inhibited autophagic flux, thereby changing cell fate of a fraction of the cell population from senescence to apoptotic cell death. Our findings highlight the synergistic effects of UV radiation and UPM on skin aging, emphasizing the need to consider these factors in assessing the impact of environmental stressors on human health and opening opportunities for developing comprehensive approaches to protect and preserve skin integrity in the face of growing environmental challenges.

Growth differentiation factor 15 (GDF15) is a stress-responsive cytokine also known as a mitokine; however, its role in mitochondrial homeostasis and cellular senescence remained elusive. We show here that knocking down GDF15 expression in human dermal fibroblasts induced mitochondrial dysfunction and premature senescence, associated with a distinct senescence-associated secretory phenotype. Fibroblast-specific loss of GDF15 expression in a model of 3D reconstructed human skin induced epidermal thinning, a hallmark of skin aging. Our results suggest GDF15 to play a so far undisclosed role in mitochondrial homeostasis to delay both the onset of cellular senescence and the appearance of age-related changes in a 3D human skin model.

Organismal aging is normally accompanied by an increase in the number of senescent cells, growth-arrested metabolic active cells that affect normal tissue function. These cells present a series of characteristics that have been studied over the last few decades. The damage in cellular organelles disbalances the cellular homeostatic processes, altering the behavior of these cells. Lysosomal dysfunction is emerging as an important factor that could regulate the production of inflammatory molecules, metabolic cellular state, or mitochondrial function.

The human skin is exposed daily to different environmental factors such as air pollutants and ultraviolet (UV) light. Air pollution is considered a harmful environmental risk to human skin and is known to promote aging and inflammation of this tissue, leading to the onset of skin disorders and to the appearance of wrinkles and pigmentation issues. Besides this, components of air pollution can interact synergistically with ultraviolet light and increase the impact of damage to the skin. However, little is known about the modulation of air pollution on cellular senescence in skin cells and how this can contribute to skin aging. In this review, we are summarizing the current state of knowledge about air pollution components, their involvement in the processes of cellular senescence and skin aging, as well as the current therapeutic and cosmetic interventions proposed to prevent or mitigate the effects of air pollution in the skin.

The mitochondrial enzyme fumarylacetoacetate hydrolase domain‐containing protein 1 (FAHD1) was identified to be upregulated in breast cancer tissues. Here, we show that FAHD1 is indispensable for the survival of BT‐20 cells, representing the basal breast cancer cell type. A lentiviral knock‐down of FAHD1 in the breast cancer cell lines MCF‐7 and BT‐20 results in lower succinate dehydrogenase (complex II) activity. In luminal MCF‐7 cells, this leads to reduced proliferation when cultured in medium containing only glutamine as the carbon source. Of note, both cell lines show attenuated protein levels of the enzyme glutaminase (GLS) which activates programmed cell death in BT‐20. These findings demonstrate that FAHD1 is crucial for the functionality of complex II in breast cancer cells and acts on glutaminolysis in the mitochondria.

Previous work has shown increased expression of genes related to oxidative stress in nonlesional atopic dermatitis (ADNL) skin. Although mitochondria are key regulators of ROS production, their function in AD has never been investigated. Energy metabolism and the oxidative stress response were studied in keratinocytes (KCs) from patients with ADNL or healthy controls. Moreover, ADNL human epidermal equivalents were treated with tigecycline or MitoQ. We found that pyruvate and glucose were used as energy substrates by ADNL KCs. Increased mitochondrial oxidation of (very) long-chain fatty acids, associated with enhanced complexes I and II activities, was observed in ADNL KCs. Metabolomic analysis revealed increased tricarboxylic acid cycle turnover. Increased aerobic metabolism generated oxidative stress in ADNL KCs. ADNL human epidermal equivalents displayed increased mitochondrial function and an enhanced oxidative stress response compared with controls. Treatment of ADNL human epidermal equivalents with tigecycline or MitoQ largely corrected the AD profile, including high p-65 NF-κB, abnormal lamellar bodies, and cellular damage. Furthermore, we found that glycolysis supports but does not supersede mitochondrial metabolism in ADNL KCs. Thus, aerobic metabolism predominates in ADNL but leads to oxidative stress. Therefore, mitochondria could be a reservoir of potential therapeutic targets in atopic dermatitis.

Additional file 1: Table S1. Statistical analysis of stress resistance data. Accompanies Fig. 1. Worms of the strains indicated were subjected to heat or oxidative stress as specified in the individual table headlines. For each biological replicate of the respective experiment, the table lists mean and median survival times in h, standard deviations and standard errors of the mean, the number of worms scored, and p-values from Kaplan-Meier survival analysis with Mantel-Cox tests against the control-, daf-16(−) or mbk-1(−) strain of the same genetic background. In case of the GSC(−) and daf-2(−) control strain, survival analysis was performed relative to the GSC(+) or daf-2(+) control strain. Repeated measures two-way ANOVA with Bonferroni post tests was performed on the mean survival times determined in the individual biological replicates of the experiments. Statistically significant p-values (* p 1.5 (Log2FC > 0.58) for genes upregulated upon mbk-1 loss. Expression of these genes is normally repressed by mbk-1 (mbk-1 repressed DEGs). In addition, the table lists DEGs detected in control comparisons between the following strains (all mbk-1(+)): downregulated 1.5-fold in daf-2(−) relative to daf-2(+); downregulated 4-fold (Log2FC > 2) in GSC(−) relative to GSC(+). See Additional file 2 for full DESeq2-data. Table S4. Overlaps of mbk-1 dependent DEGs in the genetic backgrounds analyzed in this study. Accompanies Fig. 2c, d. (a) Pairwise overlaps between DEG-lists. For each overlap, the number of genes shared between the two particular lists, the representation factor, and the p-value (in italics; hypergeometric probability) are indicated. Statistically significant overlaps are highlighted in blue. (b) Absolute numbers of mbk-1 dependent DEGs that are induced/repressed exclusively in the background indicated, or that are also induced/repressed in one or more of the three other backgrounds. (c) Percentages of mbk-1 dependent DEGs that are induced/repressed exclusively in the background indicated, or that are also induced/repressed in one or more of the three other backgrounds. Table S5. Overlap of genes regulated by mbk-1 in this work and by daf-16 in published studies. For each overlap, the number of genes shared between the two particular lists, the representation factor, and the p-value (in italics; hypergeometric probability) are indicated. Statistically significant overlaps (p

Background In the nematode Caenorhabditis elegans , longevity in response to germline ablation, but not in response to reduced insulin/IGF1-like signaling, is strongly dependent on the conserved protein kinase minibrain-related kinase 1 (MBK-1). In humans, the MBK-1 ortholog DYRK1A is associated with a variety of disorders, most prominently with neurological defects observed in Down syndrome. To better understand mbk-1 ’s physiological roles and their dependence on genetic background, we analyzed the influence of mbk-1 loss on the transcriptomes of wildtype and long-lived, germline-deficient or insulin-receptor defective, C. elegans strains by RNA-sequencing. Results mbk-1 loss elicited global changes in transcription that were less pronounced in insulin-receptor mutant than in germline-deficient or wildtype C. elegans . Irrespective of genetic background, mbk-1 regulated genes were enriched for functions in biological processes related to organic acid metabolism and pathogen defense. qPCR-studies confirmed mbk-1 dependent induction of all three C. elegans Δ9-fatty acid desaturases, fat-5 , fat-6 and fat-7 , in wildtype, germline-deficient and insulin-receptor mutant strains. Conversely, mbk-1 dependent expression patterns of selected pathogen resistance genes, including asp-12 , dod-24 and drd-50 , differed across the genetic backgrounds examined. Finally, cth-1 and cysl-2 , two genes which connect pathogen resistance to the metabolism of the gaseous messenger and lifespan regulator hydrogen sulfide (H 2 S), were commonly suppressed by mbk-1 loss only in wildtype and germline-deficient, but not in insulin-receptor mutant C. elegans . Conclusion Our work reveals previously unknown roles of C. elegans mbk-1 in the regulation of fatty acid desaturase- and H 2 S metabolic-genes. These roles are only partially dependent on genetic background. Considering the particular importance of fatty acid desaturation and H 2 S for longevity of germline-deficient C. elegans , we propose that these processes at least in part account for the previous observation that mbk-1 preferentially regulates lifespan in these worms.

AbstractThe maternal mode of mitochondrial DNA (mtDNA) inheritance is central to human genetics. Recently, evidence for bi-parental inheritance of mtDNA was claimed for individuals of three pedigrees that suffered mitochondrial disorders. We sequenced mtDNA using both direct Sanger and Massively Parallel Sequencing in several tissues of eleven maternally related and other affiliated healthy individuals of a family pedigree and observed mixed mitotypes in eight individuals. Cells without nuclear DNA, i.e. thrombocytes and hair shafts, only showed the mitotype of haplogroup (hg) V. Skin biopsies were prepared to generate ρ° cells void of mtDNA, sequencing of which resulted in a hg U4c1 mitotype. The position of the Mega-NUMT sequence was determined by fluorescence in situ hybridization and two different quantitative PCR assays were used to determine the number of contributing mtDNA copies. Thus, evidence for the presence of repetitive, full mitogenome Mega-NUMTs matching haplogroup U4c1 in various tissues of eight maternally related individuals was provided. Multi-copy Mega-NUMTs mimic mixtures of mtDNA that cannot be experimentally avoided and thus may appear in diverse fields of mtDNA research and diagnostics. We demonstrate that hair shaft mtDNA sequencing provides a simple but reliable approach to exclude NUMTs as source of misleading results.