A new AMPK isoform mediates glucose-restriction induced longevity non-cell autonomously by promoting membrane fluidity

High glucose induces FABP3-mediated membrane rigidity via downregulation of SIRT1

High glucose induces an atypical lipid composition in skeletal muscle, leading to loss of muscle mass and strength. However, the mechanisms underlying this glucose toxicity are not fully understood. Analysis of genes associated with a phenotype using the BXD phenome resource revealed that increased Fabp3 expression in skeletal muscle correlated with hyperglycemia. FABP3 expression was also increased in hyperglycemic mouse models such as leptin-deficient ob/ob, Ins2Akita, and high-fat fed mice, as well as in aged mice. In cultured myotubes, high glucose elevated the mRNA and protein levels of FABP3, which contributes to decreased membrane fluidity, along with other mechanisms. FABP3 expression was dependent on the NAD+/NADH ratio and SIRT1 activity, suggesting a mechanism by which FABP3 is upregulated in hyperglycemic conditions. Our findings propose that FABP3 links hyperglycemia to atypical membrane physicochemical properties, which may weaken contractile and metabolic function, particularly in skeletal muscle.

Chemiosmotic ATP synthesis by minimal protocells

Energy conservation is crucial to life's origin and evolution. The common ancestor of all cells used ATP synthase to convert proton gradients into ATP. However, pumps generating proton gradients and lipids maintaining proton gradients are not universally conserved across all lineages. A solution to this paradox is that ancestral ATP synthase could harness naturally formed geochemical ion gradients with simpler environmentally provided precursors preceding both proton pumps and biogenic membranes. This runs counter to traditional views that phospholipid bilayers are required to maintain proton gradients. Here, we show that fatty acid membranes can maintain sufficient proton gradients to synthesize ATP by ATP synthase under the steep pH and temperature gradients observed in hydrothermal vent systems. These findings shed substantial light on early membrane bioenergetics, uncovering a functional intermediate in the evolution of chemiosmotic ATP synthesis during protocellular stages postdating the ATP synthase's origin but preceding the advent of enzymatically synthesized cell membranes.

Crassifolin A prolongs lifespan and healthspan in Caenorhabditis elegans via activating autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Croton crassifolius Geiseler (C. crassifolius), commonly known as "Jiguxiang" in traditional Chinese medicine, is globally recognized for its ethnomedical applications in treating a spectrum of diseases. Crassifolin A (CA), a diterpenoid compound extracted from the roots of C. crassifolius, exhibits anti-herpes simplex virus (HSV), anti-viral and anti-angiogenic properties.

AIM OF THE REVIEW

This study aimed to explore the effects of CA on aging and the mechanisms involved.

MATERIALS AND METHODS

Utilizing Caenorhabditis elegans (C. elegans) as a model organism, we conducted a comprehensive survival analysis and evaluated aging-related phenotypes, including the period of fast body movement and body bending rates. To elucidate the molecular mechanisms of CA's impact on aging, we employed a multifaceted approach, including reverse transcription quantitative polymerase chain reaction (RT-qPCR), western blotting, and fluorescence quantification of transgenic reporter strains.

RESULTS

Our findings demonstrated that CA significantly prolonged both the lifespan and healthspan of C. elegans. The survival benefits conferred by CA were found to correlate with the activation of several key aging-related signaling pathways, including insulin/insulin-like signaling pathway (IIS), dietary restriction (DR) pathway, and germline signaling pathway. Engagement of these pathways led to the activation of transcription factors DAF-16/FOXO, SKN-1/NRF2, HSF-1 and HLH-30/TFEB, as well as the nuclear receptor DAF-12. Consequently, this activation cascade prompted an upregulation of autophagy, a cellular process associated with the maintenance of cellular homeostasis and longevity.

CONCLUSION

Our study delineates novel mechanisms underlying anti-aging strategies, establishing a conceptual framework for the exploitation and advancement of traditional Chinese medicinal herbs as potential therapeutic agents in the fight against aging and its associated pathologies.

Patchouli essential oil extends the lifespan and healthspan of Caenorhabditis elegans through JNK-1/DAF-16

AIMS

Patchouli essential oil (PEO) is the major active ingredient of a famous medicinal plant Pogostemon cablin (Blanco) Benth. This study aims to investigate the anti-aging activities of PEO and its major component, and elucidate the underlying molecular mechanisms.

MAIN METHODS

The anti-aging activities of PEO and its main component patchouli alcohol (PA) were investigated by examining the lifespan, senescence associated indicators as well as stress resistance of Caenorhabditis elegans. RNA-Sequencing was performed to analyze differentially expressed genes and the enrichments of GO and KEGG pathways in nematodes treated with PEO. The potential anti-aging target was predicted using a network pharmacology method and molecular docking. The underlying mechanism of senescence-delaying action was explored using C. elegans mutants and GFP transgenic strains.

KEY FINDINGS

PEO modulated lifespan and healthspan extension of worms, ameliorated the senescence characterizations, and increased the survival in stress resistance assays. PEO reduced spawning, lipid accumulation and reactive oxygen species (ROS) levels of nematodes. The levels of anti-oxidative genes and proteins were obviously upregulated after PEO treatment. Moreover, PA was identified to be an ingredient for PEO-mediated nematode longevity. The JNK-1/DAF-16 signaling pathway played a critical role in PEO/PA-mediated longevity.

SIGNIFICANCE

The findings revealed that PEO and its major component PA showed significant anti-aging activity through modulating the JNK-1/DAF-16 signaling pathway, which provides a promising strategy to treat aging and age-related diseases.

Dietary Restriction and Lipid Metabolism: Unveiling Pathways to Extended Healthspan

Dietary restriction (DR) has been reported to be a significant intervention that influences lipid metabolism and potentially modulates the aging process in a wide range of organisms. Lipid metabolism plays a pivotal role in the regulation of aging and longevity. In this review, we summarize studies on the significant role of lipid metabolism in aging in relation to DR. As a potent intervention to slow down aging, DR has demonstrated promising effects on lipid metabolism, influencing the aging processes across various species. The current review focuses on the relationships among DR-related molecular signaling proteins such as the sirtuins, signaling pathways such as the target of rapamycin and the insulin/insulin-like growth factor (IGF)-1, lipid metabolism, and aging. Furthermore, the review presents research results on diet-associated changes in cell membrane lipids and alterations in lipid metabolism caused by commensal bacteria, highlighting the importance of lipid metabolism in aging. Overall, the review explores the interplay between diet, lipid metabolism, and aging, while presenting untapped areas for further understanding of the aging process.

Long-term exposure to third-hand smoke could accelerate biological aging via mitochondrial dysfunction: Evidence from population and animal studies

The relationship between third-hand smoke (THS) exposure and lifespan remains inadequately explored. Our study sought to clarify the effects of THS on aging and lifespan. In this pursuit, our cross-sectional analysis assessed hematological aging markers in 986 non-smokers and examined lifespan alterations using a Drosophila model. THS exposure levels were quantified through survey metrics consistent with the Global Adult Tobacco Survey. The findings revealed that THS exposure significantly accelerated biological aging, with exposed individuals exhibiting an average increase in biological age of 3.04 years compared to their unexposed counterparts (p < 0.05). Correspondingly, the Drosophila model reflected these outcomes, showing a reduction in lifespan by 16.07 days (p < 0.01). Proteomic analyses identified MRPL2 as a pivotal protein in THS-induced aging, linking its expression to mitochondrial dysfunction and oxidative stress. Further metabolomic profiling highlighted disruptions in energy metabolism pathways. Follow-up in vitro experiments confirmed the role of MRPL2 in the aging processes at the cellular level. Overall, our results indicate that THS exposure is a significant accelerant of aging, providing new perspectives on the health consequences of environmental smoke residues.

Potential probiotic Lactiplantibacillus plantarum DS1800 extends lifespan and enhances stress resistance in Caenorhabditis elegans model

Probiotics are live microorganisms that provide health benefits when administered in appropriate amounts by improving or restoring the balance of intestinal microbiota. Various functional probiotic products have been developed due to the growing interest in the health-promoting and anti-aging effects of enhancing the gut microbiome. Lactiplantibacillus plantarum species are known for their potential to extend lifespan. However, this activity is strain or isolation source specific, necessitating the identification of individual strain functionalities. This study used the C. elegans model to screen probiotics for life-extension effects and analyze their functions. The 43 lactic-acid bacteria strains isolated from fermented foods, breast milk, and human feces were subjected to longevity assays, and L. plantarum DS1800 was selected to demonstrate the most effective lifespan extension. The average lifespan of Caenorhabditis elegans fed DS1800 increased by 17.36% compared with those fed Escherichia coli OP50. Further analysis of the expression of key genes related to longevity revealed the high expression of the skinhead-1 (skn-1), antibacterial, and heat stress resistance genes via the p38 MAPK pathway. These expression patterns suggest that DS1800 extends the lifespan of C. elegans by enhancing its stress resistance and protecting it against pathogens. Additionally, DS1800 exhibited excellent intestinal adhesion, with 7.56% adhesion to HT-29 cells. Therefore, L. plantarum DS1800 is effective in extending the lifespan of C. elegans and can be used as a functional probiotic.

Regulator of Lipid Metabolism NHR-49 Mediates Pathogen Avoidance through Precise Control of Neuronal Activity

Precise control of neuronal activity is crucial for the proper functioning of neurons. How lipid homeostasis contributes to neuronal activity and how much of it is regulated by cells autonomously is unclear. In this study, we discovered that absence of the lipid regulator nhr-49, a functional ortholog of the peroxisome proliferator-activated receptor (PPAR) in Caenorhabditis elegans, resulted in defective pathogen avoidance behavior against Pseudomonas aeruginosa (PA14). Functional NHR-49 was required in the neurons, and more specifically, in a set of oxygen-sensing body cavity neurons, URX, AQR, and PQR. We found that lowering the neuronal activity of the body cavity neurons improved avoidance in nhr-49 mutants. Calcium imaging in URX neurons showed that nhr-49 mutants displayed longer-lasting calcium transients in response to an O2 upshift, suggesting that excess neuronal activity leads to avoidance defects. Cell-specific rescue of NHR-49 in the body cavity neurons was sufficient to improve pathogen avoidance, as well as URX neuron calcium kinetics. Supplementation with oleic acid also improved avoidance behavior and URX calcium kinetics, suggesting that the defective calcium response in the neuron is due to lipid dysfunction. These findings highlight the role of cell-autonomous lipid regulation in neuronal physiology and immune behavior.

SuperAgers and centenarians, dynamics of healthy ageing with cognitive resilience

Graceful healthy ageing and extended longevity is the most desired goal for human race. The process of ageing is inevitable and has a profound impact on the gradual deterioration of our physiology and health since it triggers the onset of many chronic conditions like dementia, osteoporosis, diabetes, arthritis, cancer, and cardiovascular disease. However, some people who lived/live more than 100 years called 'Centenarians" and how do they achieve their extended lifespans are not completely understood. Studying these unknown factors of longevity is important not only to establish a longer human lifespan but also to manage and treat people with shortened lifespans suffering from age-related morbidities. Furthermore, older adults who maintain strong cognitive function are referred to as "SuperAgers" and may be resistant to risk factors linked to cognitive decline. Investigating the mechanisms underlying their cognitive resilience may contribute to the development of therapeutic strategies that support the preservation of cognitive function as people age. The key to a long, physically, and cognitively healthy life has been a mystery to scientists for ages. Developments in the medical sciences helps us to a better understanding of human physiological function and greater access to medical care has led us to an increase in life expectancy. Moreover, inheriting favorable genetic traits and adopting a healthy lifestyle play pivotal roles in promoting longer and healthier lives. Engaging in regular physical activity, maintaining a balanced diet, and avoiding harmful habits such as smoking contribute to overall well-being. The synergy between positive lifestyle choices, access to education, socio-economic factors, environmental determinants and genetic supremacy enhances the potential for a longer and healthier life. Our article aims to examine the factors associated with healthy ageing, particularly focusing on cognitive health in centenarians. We will also be discussing different aspects of ageing including genomic instability, metabolic burden, oxidative stress and inflammation, mitochondrial dysfunction, cellular senescence, immunosenescence, and sarcopenia.

Mitochondrial energy state controls AMPK-mediated foraging behavior in C. elegans

Organisms surveil and respond to their environment using behaviors entrained by metabolic cues that reflect food availability. Mitochondria act as metabolic hubs and at the center of mitochondrial energy production is the protonmotive force (PMF), an electrochemical gradient generated by metabolite consumption. The PMF serves as a central integrator of mitochondrial status, but its role in governing metabolic signaling is poorly understood. We used optogenetics to dissipate the PMF in Caenorhabditis elegans tissues to test its role in food-related behaviors. Our data demonstrate that PMF reduction in the intestine is sufficient to initiate locomotor responses to acute food deprivation. This behavioral adaptation requires the cellular energy regulator AMP-activated protein kinase (AMPK) in neurons, not in the intestine, and relies on mitochondrial dynamics and axonal trafficking. Our results highlight a role for intestinal PMF as an internal metabolic cue, and we identify a bottom-up signaling axis through which changes in the PMF trigger AMPK activity in neurons to promote foraging behavior.

FA2H controls cool temperature sensing through modifying membrane sphingolipids in Drosophila

Animals have evolved the ability to detect ambient temperatures, allowing them to search for optimal living environments. In search of the molecules responsible for cold-sensing, we examined a Gal4 insertion line in the larvae of Drosophila melanogaster from previous screening work, which has a specific expression pattern in the cooling cells (CCs). We identified that the targeted gene, fa2h, which encodes a fatty acid 2-hydroxylase, plays an important role in cool temperature sensing. We found that fa2h mutants exhibit defects in cool avoidance behavior and that this phenotype could be rescued by genetically re-introducing the wild-type version of FA2H in CCs but not the enzymatically disabled point mutation version. Calcium imaging data showed that CCs require fa2h to respond to cool temperature. Lipidomic analysis revealed that the 2-hydroxy sphingolipids content in the cell membranes diminished in fa2h mutants, resulting in increased fluidity of CC neuron membranes. Furthermore, in mammalian systems, we showed that FA2H strongly regulates the function of the TRPV4 channel in response to its agonist treatment and warming. Taken together, our study has uncovered a novel role of FA2H in temperature sensing and has provided new insights into the link between membrane lipid composition and the function of temperature-sensing ion channels.

Maackiain Mimics Caloric Restriction through aak-2-Mediated Lipid Reduction in Caenorhabditis elegans

Obesity prevalence is becoming a serious global health and economic issue and is a major risk factor for concomitant diseases that worsen the quality and duration of life. Therefore, the urgency of the development of novel therapies is of a particular importance. A previous study of ours revealed that the natural pterocarpan, maackiain (MACK), significantly inhibits adipogenic differentiation in human adipocytes through a peroxisome proliferator-activated receptor gamma (PPARγ)-dependent mechanism. Considering the observed anti-adipogenic potential of MACK, we aimed to further elucidate the molecular mechanisms that drive its biological activity in a Caenorhabditis elegans obesity model. Therefore, in the current study, the anti-obesogenic effect of MACK (25, 50, and 100 μM) was compared to orlistat (ORST, 12 μM) as a reference drug. Additionally, the hybrid combination between the ORST (12 μM) and MACK (100 μM) was assessed for suspected synergistic interaction. Mechanistically, the observed anti-obesogenic effect of MACK was mediated through the upregulation of the key metabolic regulators, namely, the nuclear hormone receptor 49 (nhr-49) that is a functional homologue of the mammalian PPARs and the AMP-activated protein kinase (aak-2/AMPK) in C. elegans. Collectively, our investigation indicates that MACK has the potential to limit lipid accumulation and control obesity that deserves future developments.

Glycerol 3-phosphate phosphatase/PGPH-2 counters metabolic stress and promotes healthy aging via a glycogen sensing-AMPK-HLH-30-autophagy axis in C. elegans

Metabolic stress caused by excess nutrients accelerates aging. We recently demonstrated that the newly discovered enzyme glycerol-3-phosphate phosphatase (G3PP; gene Pgp), which operates an evolutionarily conserved glycerol shunt that hydrolyzes glucose-derived glycerol-3-phosphate to glycerol, counters metabolic stress and promotes healthy aging in C. elegans. However, the mechanism whereby G3PP activation extends healthspan and lifespan, particularly under glucotoxicity, remained unknown. Here, we show that the overexpression of the C. elegans G3PP homolog, PGPH-2, decreases fat levels and mimics, in part, the beneficial effects of calorie restriction, particularly in glucotoxicity conditions, without reducing food intake. PGPH-2 overexpression depletes glycogen stores activating AMP-activate protein kinase, which leads to the HLH-30 nuclear translocation and activation of autophagy, promoting healthy aging. Transcriptomics reveal an HLH-30-dependent longevity and catabolic gene expression signature with PGPH-2 overexpression. Thus, G3PP overexpression activates three key longevity factors, AMPK, the TFEB homolog HLH-30, and autophagy, and may be an attractive target for age-related metabolic disorders linked to excess nutrients.

Metabolic regulation of endothelial senescence

Endothelial cell (EC) senescence is increasingly recognized as a significant contributor to the development of vascular dysfunction and age-related disorders and diseases, including cancer and cardiovascular diseases (CVD). The regulation of cellular senescence is known to be influenced by cellular metabolism. While extensive research has been conducted on the metabolic regulation of senescence in other cells such as cancer cells and fibroblasts, our understanding of the metabolic regulation of EC senescence remains limited. The specific metabolic changes that drive EC senescence are yet to be fully elucidated. The objective of this review is to provide an overview of the intricate interplay between cellular metabolism and senescence, with a particular emphasis on recent advancements in understanding the metabolic changes preceding cellular senescence. I will summarize the current knowledge on the metabolic regulation of EC senescence, aiming to offer insights into the underlying mechanisms and future research directions.

Nuclear hormone receptor NHR-49 is an essential regulator of stress resilience and healthy aging in Caenorhabditis elegans

The genome of Caenorhabditis elegans encodes 284 nuclear hormone receptor, which perform diverse functions in development and physiology. One of the best characterized of these is NHR-49, related in sequence and function to mammalian hepatocyte nuclear factor 4α and peroxisome proliferator-activated receptor α. Initially identified as regulator of lipid metabolism, including fatty acid catabolism and desaturation, additional important roles for NHR-49 have since emerged. It is an essential contributor to longevity in several genetic and environmental contexts, and also plays vital roles in the resistance to several stresses and innate immune response to infection with various bacterial pathogens. Here, we review how NHR-49 is integrated into pertinent signaling circuits and how it achieves its diverse functions. We also highlight areas for future investigation including identification of regulatory inputs that drive NHR-49 activity and identification of tissue-specific gene regulatory outputs. We anticipate that future work on this protein will provide information that could be useful for developing strategies to age-associated declines in health and age-related human diseases.

Molecular Mechanisms of Lipid-Based Metabolic Adaptation Strategies in Response to Cold

Temperature changes and periods of detrimental cold occur frequently for many organisms in their natural habitats. Homeothermic animals have evolved metabolic adaptation strategies to increase mitochondrial-based energy expenditure and heat production, largely relying on fat as a fuel source. Alternatively, certain species are able to repress their metabolism during cold periods and enter a state of decreased physiological activity known as torpor. By contrast, poikilotherms, which are unable to maintain their internal temperature, predominantly increase membrane fluidity to diminish cold-related damage from low-temperature stress. However, alterations of molecular pathways and the regulation of lipid-metabolic reprogramming during cold exposure are poorly understood. Here, we review organismal responses that adjust fat metabolism during detrimental cold stress. Cold-related changes in membranes are detected by membrane-bound sensors, which signal to downstream transcriptional effectors, including nuclear hormone receptors of the PPAR (peroxisome proliferator-activated receptor) subfamily. PPARs control lipid metabolic processes, such as fatty acid desaturation, lipid catabolism and mitochondrial-based thermogenesis. Elucidating the underlying molecular mechanisms of cold adaptation may improve beneficial therapeutic cold treatments and could have important implications for medical applications of hypothermia in humans. This includes treatment strategies for hemorrhagic shock, stroke, obesity and cancer.

Humanin and Its Pathophysiological Roles in Aging: A Systematic Review

BACKGROUND

Senescence is a cellular aging process in all multicellular organisms. It is characterized by a decline in cellular functions and proliferation, resulting in increased cellular damage and death. These conditions play an essential role in aging and significantly contribute to the development of age-related complications. Humanin is a mitochondrial-derived peptide (MDP), encoded by mitochondrial DNA, playing a cytoprotective role to preserve mitochondrial function and cell viability under stressful and senescence conditions. For these reasons, humanin can be exploited in strategies aiming to counteract several processes involved in aging, including cardiovascular disease, neurodegeneration, and cancer. Relevance of these conditions to aging and disease: Senescence appears to be involved in the decay in organ and tissue function, it has also been related to the development of age-related diseases, such as cardiovascular conditions, cancer, and diabetes. In particular, senescent cells produce inflammatory cytokines and other pro-inflammatory molecules that can participate to the development of such diseases. Humanin, on the other hand, seems to contrast the development of such conditions, and it is also known to play a role in these diseases by promoting the death of damaged or malfunctioning cells and contributing to the inflammation often associated with them. Both senescence and humanin-related mechanisms are complex processes that have not been fully clarified yet. Further research is needed to thoroughly understand the role of such processes in aging and disease and identify potential interventions to target them in order to prevent or treat age-related conditions.

OBJECTIVES

This systematic review aims to assess the potential mechanisms underlying the link connecting senescence, humanin, aging, and disease.