ABSTRACT
Dietary mono-unsaturated fatty acids (MUFAs) are linked to longevity in several species. But the mechanisms by which MUFAs extend lifespan remain unclear. Here we show that an organelle network involving lipid droplets and peroxisomes is critical for MUFA-induced longevity in Caenorhabditis elegans. MUFAs upregulate the number of lipid droplets in fat storage tissues. Increased lipid droplet number is necessary for MUFA-induced longevity and predicts remaining lifespan. Lipidomics datasets reveal that MUFAs also modify the ratio of membrane lipids and ether lipids-a signature associated with decreased lipid oxidation. In agreement with this, MUFAs decrease lipid oxidation in middle-aged individuals. Intriguingly, MUFAs upregulate not only lipid droplet number but also peroxisome number. A targeted screen identifies genes involved in the co-regulation of lipid droplets and peroxisomes, and reveals that induction of both organelles is optimal for longevity. Our study uncovers an organelle network involved in lipid homeostasis and lifespan regulation, opening new avenues for interventions to delay aging.
Subject(s)
Longevity , Peroxisomes , Humans , Middle Aged , Animals , Longevity/genetics , Lipid Droplets , Fatty Acids, Unsaturated , Caenorhabditis elegans/genetics , Fatty AcidsABSTRACT
Mitochondrial form and function are closely interlinked in homeostasis and aging. Inhibiting mitochondrial translation is known to increase lifespan in C. elegans, and is accompanied by a fragmented mitochondrial network. However, whether this link between mitochondrial translation and morphology is causal in longevity remains uncharacterized. Here, we show in C. elegans that disrupting mitochondrial network homeostasis by blocking fission or fusion synergizes with reduced mitochondrial translation to prolong lifespan and stimulate stress response such as the mitochondrial unfolded protein response, UPRMT. Conversely, immobilizing the mitochondrial network through a simultaneous disruption of fission and fusion abrogates the lifespan increase induced by mitochondrial translation inhibition. Furthermore, we find that the synergistic effect of inhibiting both mitochondrial translation and dynamics on lifespan, despite stimulating UPRMT, does not require it. Instead, this lifespan-extending synergy is exclusively dependent on the lysosome biogenesis and autophagy transcription factor HLH-30/TFEB. Altogether, our study reveals the mechanistic crosstalk between mitochondrial translation, mitochondrial dynamics, and lysosomal signaling in regulating longevity.
Subject(s)
Basic Helix-Loop-Helix Transcription Factors/metabolism , Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/metabolism , Longevity/physiology , Mitochondria/metabolism , Mitochondrial Dynamics/drug effects , Protein Biosynthesis/drug effects , Animals , Autophagosomes/drug effects , Autophagosomes/metabolism , Autophagosomes/ultrastructure , Basic Helix-Loop-Helix Transcription Factors/genetics , Caenorhabditis elegans Proteins/genetics , Gene Ontology , Longevity/genetics , Lysosomes/drug effects , Lysosomes/metabolism , Lysosomes/ultrastructure , Microscopy, Electron, Transmission , Mitochondria/genetics , Protein Biosynthesis/physiology , Proteomics , RNA Interference , Reproduction/physiology , Signal Transduction/drug effects , Signal Transduction/physiology , Unfolded Protein Response/drug effects , Unfolded Protein Response/geneticsABSTRACT
Mitochondria are organized in the cell in the form of a dynamic, interconnected network. Mitochondrial dynamics, regulated by mitochondrial fission, fusion, and trafficking, ensure restructuring of this complex reticulum in response to nutrient availability, molecular signals, and cellular stress. Aberrant mitochondrial structures have long been observed in aging and age-related diseases indicating that mitochondrial dynamics are compromised as cells age. However, the specific mechanisms by which aging affects mitochondrial dynamics and whether these changes are causally or casually associated with cellular and organismal aging is not clear. Here, we review recent studies that show specifically how mitochondrial fission, fusion, and trafficking are altered with age. We discuss factors that change with age to directly or indirectly influence mitochondrial dynamics while examining causal roles for altered mitochondrial dynamics in healthy aging and underlying functional outputs that might affect longevity. Lastly, we propose that altered mitochondrial dynamics might not just be a passive consequence of aging but might constitute an adaptive mechanism to mitigate age-dependent cellular impairments and might be targeted to increase longevity and promote healthy aging.
Subject(s)
Healthy Aging/physiology , Longevity/physiology , Mitochondrial Dynamics/physiology , AMP-Activated Protein Kinases/physiology , Aging/physiology , Animals , Cellular Senescence/physiology , Host Microbial Interactions/physiology , Humans , Insulin/physiology , Microbiota/physiology , Models, Biological , Organelles/physiology , Signal Transduction , Sirtuins/physiology , Somatomedins/physiology , TOR Serine-Threonine Kinases/physiologyABSTRACT
Glucagon-like peptide-1 (GLP-1) injected into the brain reduces food intake. Similarly, activation of preproglucagon (PPG) cells in the hindbrain which synthesize GLP-1, reduces food intake. However, it is far from clear whether this happens because of satiety, nausea, reduced reward, or even stress. Here we explore the role of the bed nucleus of the stria terminalis (BNST), an area involved in feeding control as well as stress responses, in GLP-1 responses. Using cre-expressing mice we visualized projections of NTS PPG neurons and GLP-1R-expressing BNST cells with AAV-driven Channelrhodopsin-YFP expression. The BNST displayed many varicose YFP+ PPG axons in the ventral and less in the dorsal regions. Mice which express RFP in GLP-1R neurons had RFP+ cells throughout the BNST with the highest density in the dorsal part, suggesting that PPG neuron-derived GLP-1 acts in the BNST. Indeed, injection of GLP-1 into the BNST reduced chow intake during the dark phase, whereas injection of the GLP-1 receptor antagonist Ex9 increased feeding. BNST-specific GLP-1-induced food suppression was less effective in mice on high fat (HF, 60%) diet, and Ex9 had no effect. Restraint stress-induced hypophagia was attenuated by BNST Ex9 treatment, further supporting a role for endogenous brain GLP-1. Finally, whole-cell patch clamp recordings of RFP+ BNST neurons demonstrated that GLP-1 elicited either a depolarizing or hyperpolarizing reversible response that was of opposite polarity to that under dopamine. Our data support a physiological role for BNST GLP-1R in feeding, and suggest complex cellular responses to GLP-1 in this nucleus.
Subject(s)
Glucagon-Like Peptide 1/metabolism , Septal Nuclei/metabolism , Analysis of Variance , Animals , Dose-Response Relationship, Drug , Eating/drug effects , Excitatory Amino Acid Antagonists/pharmacology , Glucagon-Like Peptide 1/genetics , Glucagon-Like Peptide-1 Receptor/antagonists & inhibitors , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Male , Membrane Potentials/drug effects , Mice , Mice, Inbred C57BL , Mice, Transgenic , Patch-Clamp Techniques , Peptide Fragments/pharmacology , Proglucagon/metabolism , Quinoxalines/pharmacology , Septal Nuclei/cytology , Septal Nuclei/drug effects , Stress, Psychological/metabolism , Stress, Psychological/pathologyABSTRACT
Mitochondrial network remodeling between fused and fragmented states facilitates mitophagy, interaction with other organelles, and metabolic flexibility. Aging is associated with a loss of mitochondrial network homeostasis, but cellular processes causally linking these changes to organismal senescence remain unclear. Here, we show that AMP-activated protein kinase (AMPK) and dietary restriction (DR) promote longevity in C. elegans via maintaining mitochondrial network homeostasis and functional coordination with peroxisomes to increase fatty acid oxidation (FAO). Inhibiting fusion or fission specifically blocks AMPK- and DR-mediated longevity. Strikingly, however, preserving mitochondrial network homeostasis during aging by co-inhibition of fusion and fission is sufficient itself to increase lifespan, while dynamic network remodeling is required for intermittent fasting-mediated longevity. Finally, we show that increasing lifespan via maintaining mitochondrial network homeostasis requires FAO and peroxisomal function. Together, these data demonstrate that mechanisms that promote mitochondrial homeostasis and plasticity can be targeted to promote healthy aging.
Subject(s)
Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/physiology , Caloric Restriction , Longevity , Mitochondria/metabolism , Peroxisomes/metabolism , Protein Kinases/metabolism , AMP-Activated Protein Kinase Kinases , Aging , Animals , Cell Line , Fatty Acids/metabolism , Metabolomics , Mice , Mitochondria/ultrastructure , Mitochondrial Dynamics , Models, AnimalABSTRACT
BACKGROUND AND OBJECTIVES: Patterns of development predict cardiovascular disease (CVD) risk, and ethnic differences therein, but it remains unclear why apparently 'adaptive plasticity' in early life should generate health costs in later life. We hypothesized that offspring receiving low maternal investment during fetal life, the primary period of organogenesis, should predict a shorter reproductive career and develop a fast life-history strategy, prioritizing reproduction over growth and homeostatic maintenance. METHODOLOGY: We studied 58 young adult South Asian women living in the UK, a group with high susceptibility to CVD. We obtained gestational age, birth weight (BW) and menarcheal age by recall and measured anthropometry, body composition, resting metabolic rate (RMR) and blood pressure (BP). RESULTS: BW and gestational age were inversely associated with menarcheal age, indicating that lower maternal investment is associated with faster maturation. Menarcheal age was positively associated with height but inversely with adiposity, indicating that rapid maturation prioritizes lipid stores over somatic growth. BW was inversely associated with BP, whereas adiposity was positively associated, indicating that lower maternal investment reduces BP homeostasis. BW was positively associated with RMR, whereas menarche was inversely associated, indicating that maternal investment influences adult metabolism. CONCLUSIONS AND IMPLICATIONS: Supporting our hypothesis, low maternal investment promoted faster life histories, demonstrated by earlier menarche, reduced growth and elevated adiposity. These traits were associated with poorer BP regulation. This is the first study demonstrating strategic adjustment of the balance between reproduction and metabolic health in response to the level of maternal investment during fetal life.