Targeted expression of the human uncoupling protein 2 (hUCP2) to adult neurons extends life span in the fly

Wolbachia: A bacterial weapon against dengue fever- a narrative review of risk factors for dengue fever outbreaks

Arboviruses constitute the largest known group of viruses and are responsible for various infections that impose significant socioeconomic burdens worldwide, particularly due to their link with insect-borne diseases. The increasing incidence of dengue fever in non-endemic regions underscores the urgent need for innovative strategies to combat this public health threat. Wolbachia, a bacterium, presents a promising biological control method against mosquito vectors, offering a novel approach to managing dengue fever. We systematically investigated biomedical databases (PubMed, Web of Science, Google Scholar, Science Direct, and Embase) using "AND" as a Boolean operator with keywords such as "dengue fever," "dengue virus," "risk factors," "Wolbachia," and "outbreak." We prioritized articles that offered significant insights into the risk factors contributing to the outbreak of dengue fever and provided an overview of Wolbachia's characteristics and functions in disease management, considering studies published until December 25, 2024. Field experiments have shown that introducing Wolbachia-infected mosquitoes can effectively reduce mosquito populations and lower dengue transmission rates, signifying its potential as a practical approach for controlling this disease.

2,4-Dinitrophenol is toxic on a low caloric diet but extends lifespan of Drosophila melanogaster on nutrient-rich diets without an impact on metabolism

Uncouplers of mitochondrial electron transport chain, such as 2,4-dinitrophehol (DNP), can mimic calorie restriction by decreasing efficiency of adenosine triphosphate (ATP) synthesis. However, DNP is also a toxic substance, whose overdosage can be lethal. In the fruit fly, Drosophila melanogaster model, we have found that DNP in concentrations of 0.05-0.2 g/L, led to a drastic decrease in fruit fly survival on a low caloric diet (1% sucrose and 1% yeast; 1S-1Y). On the 5S-5Y diet, DNP decreased lifespan of flies reared only in concentration 0.2 g/L, whilst on the diet 15S-15Y DNP either did not significantly shortened fruit fly lifespan or extended it. The lifespan extension on the high caloric 15S-15Y diet with DNP was accompanied by lower activity of lactate dehydrogenase and a decrease in activities of mitochondrial respiratory chain complexes I, II, and V, determined by blue native electrophoresis followed by in-gel activity assays. The exposure to DNP also did not affect key glycolytic enzymes, antioxidant and related enzymes, and markers of oxidative stress, such as aconitase activity and amount protein carbonyls. Consumption of DNP-supplemented diet did not affect flies' resistance to heat stress, though made male flies slightly more resistant to starvation compared with males reared on the control food. We also did not observe substantial changes in the contents of metabolic stores, triacylglycerols and glycogen, in the DNP-treated flies. All this suggest that a nutrient-rich diets provide effective protection against DNP, providing a mild uncoupling of the respiratory chain that allows lifespan extension without considerable changes in metabolism.

Chlorella pyrenoidosa polysaccharides supplementation increases Drosophila melanogaster longevity at high temperature

Chlorella pyrenoidos polysaccharides (CPPs) are the main active components of Chlorella pyrenoidos. They possess beneficial health properties, such as antioxidant, anti-inflammatory, and immune-enhancing. This study aims to investigate the protective function and mechanism of CPPs against high-temperature stress injury. Results showed that supplementation with 20 mg/mL CPPs significantly extended the lifespan of Drosophila melanogaster under high-temperature stress, improved its motility, and enhanced its resistance to starvation and oxidative stress. These effects were mainly attributed to the activation of Nrf2 signaling and enhanced antioxidant capacity. Additionally, it has been discovered that CPPs supplementation enhanced Drosophila resilience by preventing the disruption of the intestinal barrier and accumulation of reactive oxygen species caused by heat stress. Overall, these studies suggest that CPPs could be a useful natural therapy for preventing heat stress-induced injury.

Noncoupled Mitochondrial Respiration as Therapeutic Approach for the Treatment of Metabolic Diseases: Focus on Transgenic Animal Models

Mitochondrial dysfunction contributes to numerous chronic diseases, and mitochondria are targets for various toxins and xenobiotics. Therefore, the development of drugs or therapeutic strategies targeting mitochondria is an important task in modern medicine. It is well known that the primary, although not the sole, function of mitochondria is ATP generation, which is achieved by coupled respiration. However, a high membrane potential can lead to uncontrolled reactive oxygen species (ROS) production and associated dysfunction. For over 50 years, scientists have been studying various synthetic uncouplers, and for more than 30 years, uncoupling proteins that are responsible for uncoupled respiration in mitochondria. Additionally, the proteins of the mitochondrial alternative respiratory pathway exist in plant mitochondria, allowing noncoupled respiration, in which electron flow is not associated with membrane potential formation. Over the past two decades, advances in genetic engineering have facilitated the creation of various cellular and animal models that simulate the effects of uncoupled and noncoupled respiration in different tissues under various disease conditions. In this review, we summarize and discuss the findings obtained from these transgenic models. We focus on the advantages and limitations of transgenic organisms, the observed physiological and biochemical changes, and the therapeutic potential of uncoupled and noncoupled respiration.

Functional characterization of novel NPRL3 mutations identified in three families with focal epilepsy

Focal epilepsy accounts for 60% of all forms of epilepsy, but the pathogenic mechanism is not well understood. In this study, three novel mutations in NPRL3 (nitrogen permease regulator-like 3), c.937_945del, c.1514dupC and 6,706-bp genomic DNA (gDNA) deletion, were identified in three families with focal epilepsy by linkage analysis, whole exome sequencing (WES) and Sanger sequencing. NPRL3 protein is a component of the GATOR1 complex, a major inhibitor of mTOR signaling. These mutations led to truncation of the NPRL3 protein and hampered the binding between NPRL3 and DEPDC5, which is another component of the GATOR1 complex. Consequently, the mutant proteins enhanced mTOR signaling in cultured cells, possibly due to impaired inhibition of mTORC1 by GATOR1. Knockdown of nprl3 in Drosophila resulted in epilepsy-like behavior and abnormal synaptic development. Taken together, these findings expand the genotypic spectrum of NPRL3-associated focal epilepsy and provide further insight into how NPRL3 mutations lead to epilepsy.

Mitochondrial proton leak in cardiac aging

Age-associated diseases are becoming progressively more prevalent, reflecting the increased lifespan of the world's population. However, the fundamental mechanisms of physiologic aging are poorly understood, and in particular, the molecular pathways that mediate cardiac aging and its associated dysfunction are unclear. Here, we focus on certain ion flux abnormalities of the mitochondria that may contribute to cardiac aging and age-related heart failure. Using oxidative phosphorylation, mitochondria pump protons from the matrix to the intermembrane space to generate a proton gradient across the inner membrane. The protons are returned to the matrix by the ATPase complex within the membrane to generate ATP. However, a portion of protons leak back to the matrix and do not drive ATP production, and this event is called proton leak or uncoupling. Accumulating evidence suggests that mitochondrial proton leak is increased in the cardiac myocytes of aged hearts. In this mini-review, we discuss the measurement methods and major sites of mitochondrial proton leak with an emphasis on the adenine nucleotide transporter 1 (ANT1), and explore the possibility of inhibiting augmented mitochondrial proton leak as a therapeutic intervention to mitigate cardiac aging.

Changing ROS, NAD and AMP: A path to longevity via mitochondrial therapeutics

Lifespan of many organisms, from unicellular yeast to extremely complex human organism, strongly depends on the genetic background and environmental factors. Being among most influential target energy metabolism is affected by macronutrients, their caloric values, and peculiarities of catabolism. Mitochondria are central organelles that respond for energy metabolism in eukaryotic cells. Mitochondria generate reactive oxygen species (ROS), which are lifespan modifying metabolites and a kind of biological clock. Oxidized nicotinamide adenine dinucleotide (NAD⁺) and adenosine monophosphate (AMP) are important metabolic intermediates and molecules that trigger or inhibit several signaling pathways involved in gene silencing, nutrient allocation, and cell regeneration and programmed death. A part of NAD⁺ and AMP metabolism is tied to mitochondria. Using substances that able to target mitochondria, as well as allotopic expression of specific enzymes, are envisioned to be innovative approaches to prolong lifespan by modulation of ROS, NAD⁺, and AMP levels. Among substances, an anti-diabetic drug metformin is believed to increase NAD⁺ and AMP levels, indirectly influencing histone deacetylases, involved in gene silencing, and AMP-activated protein kinase, an energy sensor of cells. Mitochondrially targeted derivatives of ubiquinone were found to interact with ROS. A mitochondrially targeted non-proton-pumping NADH dehydrogenase may influence both ROS and NAD⁺ levels. Chapter describes putative how mitochondria-targeted drugs and NADH dehydrogenase extend lifespan, perspectives of creating drugs with similar properties and their usage as senotherapeutic pills are discussed in the chapter.

AAV-ie-mediated UCP2 overexpression accelerates inner hair cell loss during aging in vivo

BACKGROUND

Uncoupling protein 2 (UCP2), activated by excessive reactive oxygen species (ROS) in vivo, has the dual effect of reducing ROS to protect against oxidative stress and reducing ATP production to regulate cellular metabolism. Both the UCP2 and ROS are increased in cochleae in age-related hearing loss (ARHL). However, the role of UCP2 in sensory hair cells in ARHL remains unclear.

METHODS

Male C57BL/6 J mice were randomly assigned to an 8-week-old group (Group 1), a 16-week-old group (Group 2), a 16-week-old + adeno-associated virus-inner ear (AAV-ie) group (Group 3), and a 16-week-old + AAV-ie-UCP2 group (Group 4). Mice aged 8 weeks were administrated with AAV-ie-GFP or AAV-ie-UCP2 via posterior semicircular canal injection. Eight weeks after this viral intervention, hearing thresholds and wave-I amplitudes were tested by auditory brainstem response (ABR). Subsequently, the cochlear basilar membrane was dissected for investigation. The number of hair cells and inner hair cell (IHC) synapses, the level of ROS, and the expression of AMP-activated protein kinase α (AMPKα), were assessed by immunofluorescence staining. In addition, mitochondrial function was determined, and the expression of AMPKα and UCP2 proteins was further evaluated using western blotting.

RESULTS

Mice with early-onset ARHL exhibited enhanced oxidative stress and loss of outer hair cells and IHC synapses, while UCP2 overexpression aggravated hearing loss and cochlear pathophysiological changes in mice. UCP2 overexpression resulted in a notable decrease in the number of IHCs and IHC synapses, caused ATP depletion and excessive ROS generation, increased AMPKα protein levels, and promoted IHC apoptosis, especially in the apical and middle turns of the cochlea.

CONCLUSION

Collectively, our data suggest that UCP2 overexpression may cause mitochondrial dysfunction via energy metabolism, which activates mitochondrion-dependent cellular apoptosis and leads to IHC loss, ultimately exacerbating ARHL.

Characterizing region-specific glucose metabolic profile of the rodent brain using Seahorse XFe96 analyzer

The brain is highly complex with diverse structural characteristics in accordance with specific functions. Accordingly, differences in regional function, cellular compositions, and active metabolic pathways may link to differences in glucose metabolism at different brain regions. In the current study, we optimized an acute biopsy punching method and characterized region-specific glucose metabolism of rat and mouse brain by a Seahorse XFe96 analyzer. We demonstrated that 0.5 mm diameter tissue punches from 180-µm thick brain sections allow metabolic measurements of anatomically defined brain structures using Seahorse XFe96 analyzer. Our result indicated that the cerebellum displays a more quiescent phenotype of glucose metabolism than cerebral cortex, basal ganglia, and hippocampus. In addition, the cerebellum has higher AMPK activation than other brain regions evidenced by the expression of pAMPK, upstream pLKB1, and downstream pACC. Furthermore, rodent brain has relatively low mitochondrial oxidative phosphorylation efficiency with up to 30% of respiration linked to proton leak. In summary, our study discovered region-specific glucose metabolic profile and relative high proton leak coupled respiration in the brain. Our study warrants future research on spatial mapping of the brain glucose metabolism in physiological and pathological conditions and exploring the mechanisms and significance of mitochondrial uncoupling in the brain.

Regulation of Aging and Longevity by Ion Channels and Transporters

Despite significant advances in our understanding of the mechanisms that underlie age-related physiological decline, our ability to translate these insights into actionable strategies to extend human healthspan has been limited. One of the major reasons for the existence of this barrier is that with a few important exceptions, many of the proteins that mediate aging have proven to be undruggable. The argument put forth here is that the amenability of ion channels and transporters to pharmacological manipulation could be leveraged to develop novel therapeutic strategies to combat aging. This review delves into the established roles for ion channels and transporters in the regulation of aging and longevity via their influence on membrane excitability, Ca2+ homeostasis, mitochondrial and endolysosomal function, and the transduction of sensory stimuli. The goal is to provide the reader with an understanding of emergent themes, and prompt further investigation into how the activities of ion channels and transporters sculpt the trajectories of cellular and organismal aging.

Sex- and strain-specific effects of mitochondrial uncoupling on age-related metabolic diseases in high-fat diet-fed mice

Mild uncoupling of oxidative phosphorylation is an intrinsic property of all mitochondria and may have evolved to protect cells against the production of damaging reactive oxygen species. Therefore, compounds that enhance mitochondrial uncoupling are potentially attractive anti‐aging therapies; however, chronic ingestion is associated with a number of unwanted side effects. We have previously developed a controlled‐release mitochondrial protonophore (CRMP) that is functionally liver‐directed and promotes oxidation of hepatic triglycerides by causing a subtle sustained increase in hepatic mitochondrial inefficiency. Here, we sought to leverage the higher therapeutic index of CRMP to test whether mild mitochondrial uncoupling in a liver‐directed fashion could reduce oxidative damage and improve age‐related metabolic disease and lifespan in diet‐induced obese mice. Oral administration of CRMP (20 mg/[kg‐day] × 4 weeks) reduced hepatic lipid content, protein kinase C epsilon activation, and hepatic insulin resistance in aged (74‐week‐old) high‐fat diet (HFD)‐fed C57BL/6J male mice, independently of changes in body weight, whole‐body energy expenditure, food intake, or markers of hepatic mitochondrial biogenesis. CRMP treatment was also associated with a significant reduction in hepatic lipid peroxidation, protein carbonylation, and inflammation. Importantly, long‐term (49 weeks) hepatic mitochondrial uncoupling initiated late in life (94–104 weeks), in conjugation with HFD feeding, protected mice against neoplastic disorders, including hepatocellular carcinoma (HCC), in a strain and sex‐specific manner. Taken together, these studies illustrate the complex variation of aging and provide important proof‐of‐concept data to support further studies investigating the use of liver‐directed mitochondrial uncouplers to promote healthy aging in humans.

Effects of Curcumin on Aging: Molecular Mechanisms and Experimental Evidence

Aging is characterized by a progressive inability to maintain homeostasis, self-repair, renewal, performance, and fitness of different tissues throughout the lifespan. Senescence is occurring following enormous intracellular or extracellular stress stimuli. Cellular senescence serves as an antiproliferative process that causes permanent cell cycle arrest and restricts the lifespan. Senescent cells are characterized by terminal cell cycle arrest, enlarged lysosome, and DNA double-strand breaks as well as lipofuscin granularity, senescence-associated heterochromatin foci, and activation of DNA damage response. Curcumin, a hydrophobic polyphenol, is a bioactive chemical constituent of the rhizomes of Curcuma longa Linn (turmeric), which has been extensively used for the alleviation of various human disorders. In addition to its pleiotropic effects, curcumin has been suggested to have antiaging features. In this review, we summarized the therapeutic potential of curcumin in the prevention and delaying of the aging process.

TSG101 negatively regulates mitochondrial biogenesis in axons

There is a tight association between mitochondrial dysfunction and neurodegenerative diseases and axons that are particularly vulnerable to degeneration, but how mitochondria are maintained in axons to support their physiology remains poorly defined. In an in vivo forward genetic screen for mutants altering axonal mitochondria, we identified tsg101 Neurons mutant for tsg101 exhibited an increase in mitochondrial number and decrease in mitochondrial size. TSG101 is best known as a component of the endosomal sorting complexes required for transport (ESCRT) complexes; however, loss of most other ESCRT components did not affect mitochondrial numbers or size, suggesting TSG101 regulates mitochondrial biology in a noncanonical, ESCRT-independent manner. The TSG101-mutant phenotype was not caused by lack of mitophagy, and we found that autophagy blockade was detrimental only to the mitochondria in the cell bodies, arguing mitophagy and autophagy are dispensable for the regulation of mitochondria number in axons. Interestingly, TSG101 mitochondrial phenotypes were instead caused by activation of PGC-1ɑ/Nrf2-dependent mitochondrial biogenesis, which was mTOR independent and TFEB dependent and required the mitochondrial fission-fusion machinery. Our work identifies a role for TSG101 in inhibiting mitochondrial biogenesis, which is essential for the maintenance of mitochondrial numbers and sizes, in the axonal compartment.

Downregulation of the tyrosine degradation pathway extends Drosophila lifespan

Aging is characterized by extensive metabolic reprogramming. To identify metabolic pathways associated with aging, we analyzed age-dependent changes in the metabolomes of long-lived Drosophila melanogaster. Among the metabolites that changed, levels of tyrosine were increased with age in long-lived flies. We demonstrate that the levels of enzymes in the tyrosine degradation pathway increase with age in wild-type flies. Whole-body and neuronal-specific downregulation of enzymes in the tyrosine degradation pathway significantly extends Drosophila lifespan, causes alterations of metabolites associated with increased lifespan, and upregulates the levels of tyrosine-derived neuromediators. Moreover, feeding wild-type flies with tyrosine increased their lifespan. Mechanistically, we show that suppression of ETC complex I drives the upregulation of enzymes in the tyrosine degradation pathway, an effect that can be rescued by tigecycline, an FDA-approved drug that specifically suppresses mitochondrial translation. In addition, tyrosine supplementation partially rescued lifespan of flies with ETC complex I suppression. Altogether, our study highlights the tyrosine degradation pathway as a regulator of longevity.

Cell non-autonomous regulation of health and longevity

As the demographics of the modern world skew older, understanding and mitigating the effects of aging is increasingly important within biomedical research. Recent studies in model organisms demonstrate that the aging process is frequently modified by an organism’s ability to perceive and respond to changes in its environment. Many well-studied pathways that influence aging involve sensory cells, frequently neurons, that signal to peripheral tissues and promote survival during the presence of stress. Importantly, this activation of stress response pathways is often sufficient to improve health and longevity even in the absence of stress. Here, we review the current landscape of research highlighting the importance of cell non-autonomous signaling in modulating aging from C. elegans to mammals. We also discuss emerging concepts including retrograde signaling, approaches to mapping these networks, and development of potential therapeutics.

Targeting metabolic pathways for extension of lifespan and healthspan across multiple species

Metabolism plays a significant role in the regulation of aging at different levels, and metabolic reprogramming represents a major driving force in aging. Metabolic reprogramming leads to impaired organismal fitness, an age-dependent increase in susceptibility to diseases, decreased ability to mount a stress response, and increased frailty. The complexity of age-dependent metabolic reprogramming comes from the multitude of levels on which metabolic changes can be connected to aging and regulation of lifespan. This is further complicated by the different metabolic requirements of various tissues, cross-organ communication via metabolite secretion, and direct effects of metabolites on epigenetic state and redox regulation; however, not all of these changes are causative to aging. Studies in yeast, flies, worms, and mice have played a crucial role in identifying mechanistic links between observed changes in various metabolic traits and their effects on lifespan. Here, we review how changes in the organismal and organ-specific metabolome are associated with aging and how targeting of any one of over a hundred different targets in specific metabolic pathways can extend lifespan. An important corollary is that restriction or supplementation of different metabolites can change activity of these metabolic pathways in ways that improve healthspan and extend lifespan in different organisms. Due to the high levels of conservation of metabolism in general, translating findings from model systems to human beings will allow for the development of effective strategies for human health- and lifespan extension.

Control of lifespan and survival by Drosophila NF-κB signaling through neuroendocrine cells and neuroblasts

We report a comparative analysis of the effects of immune activation in the fly nervous system using genetic activation models to target Drosophila NF-κB within Toll versus Imd pathways. Genetic gain-of-function models for either pathway pan-neuronally as well as in discrete subsets of neural cells including neuroendocrine insulin-producing cells (IPCs) or neuroblasts reduce fly lifespan, however, these phenotypes in IPCs and neuroblasts are stronger with Toll activation than Imd activation. Of note, while aging is influenced more by Toll/NF-κB activation in IPCs during adulthood, neuroblasts influence aging more substantially during development. The study then focused on Toll/NF-κB inhibition, revealing that IPCs or neuroblasts are important for the effects of lifespan and healthspan extension but in a life stage-dependent manner while some of these effects display sexual dimorphism. Importantly, co-inhibition of Toll/NF-κB pathway in IPCs and neuroblasts increased fly lifespan greater than either cell population, suggesting that independent mechanisms might exist. Toll/NF-κB inhibition in IPCs was also sufficient to enhance survival under various fatal stresses, supporting the additional benefits to fly healthspan. In conclusion, IPCs and neuroblasts are important for Drosophila NF-κB for controlling lifespan.

Transcriptome responses to elevated CO2 level and Wolbachia-infection stress in Hylyphantes graminicola (Araneae: Linyphiidae)

Hylyphantes graminicola is a resident spider species found in maize and cotton fields and is an important biological control agent of various pests. Previous studies have demonstrated that stress from elevated CO₂ and Wolbachia infection can strongly affect spider species. Thus, based on CO₂ levels (400 ppm, current atmospheric CO₂ concentration and 800 ppm, high CO₂ concentration) and Wolbachia status (Wolbachia-infected, W⁺ and Wolbachia-uninfected, W^- ), we divided H. graminicola individuals into four treatment groups: W^- 400 ppm, W^- 800 ppm, W⁺ 400 ppm, and W⁺ 800 ppm. To investigate the effects of elevated CO₂ levels (W^- 400 vs W^- 800), Wolbachia infection (W^- 400 vs W⁺ 400), and the interactions between these two factors (W^- 400 vs W⁺ 800), high-throughput transcriptome sequencing was employed to characterize the de novo transcriptome of the spiders and identify stress-related differentially expressed genes (DEGs). De novo assembly of complementary DNA sequences generated 86 688 unigenes, 23 938 of which were annotated in public databases. A total of 84, 21, and 157 DEGs were found among W^- 400 vs W^- 800, W^- 400 vs W⁺ 400, and W^- 400 vs W⁺ 800, respectively. Functional enrichment analysis revealed that metabolic processes, signaling, and catalytic activity were significantly affected by elevated CO₂ levels and Wolbachia infection. Our findings suggest that the impact of elevated CO₂ levels and Wolbachia infection on the H. graminicola transcriptome was, to a large extent, on genes involved in metabolic processes. This study is the first description of transcriptome changes in response to elevated CO₂ levels and Wolbachia infection in spiders.

JNK signalling regulates antioxidant responses in neurons

Reactive oxygen species (ROS) are generated during physiological bouts of synaptic activity and as a consequence of pathological conditions in the central nervous system. How neurons respond to and distinguish between ROS in these different contexts is currently unknown. In Drosophila mutants with enhanced JNK activity, lower levels of ROS are observed and these animals are resistant to both changes in ROS and changes in synapse morphology induced by oxidative stress. In wild type flies, disrupting JNK-AP-1 signalling perturbs redox homeostasis suggesting JNK activity positively regulates neuronal antioxidant defense. We validated this hypothesis in mammalian neurons, finding that JNK activity regulates the expression of the antioxidant gene Srxn-1, in a c-Jun dependent manner. We describe a conserved ‘adaptive’ role for neuronal JNK in the maintenance of redox homeostasis that is relevant to several neurodegenerative diseases.

Transcriptomics-Based Screening Identifies Pharmacological Inhibition of Hsp90 as a Means to Defer Aging

Aging strongly influences human morbidity and mortality. Thus, aging-preventive compounds could greatly improve our health and lifespan. Here we screened for such compounds, known as geroprotectors, employing the power of transcriptomics to predict biological age. Using age-stratified human tissue transcriptomes and machine learning, we generated age classifiers and applied these to transcriptomic changes induced by 1,309 different compounds in human cells, ranking these compounds by their ability to induce a “youthful” transcriptional state. Testing the top candidates in C. elegans, we identified two Hsp90 inhibitors, monorden and tanespimycin, which extended the animals’ lifespan and improved their health. Hsp90 inhibition induces expression of heat shock proteins known to improve protein homeostasis. Consistently, monorden treatment improved the survival of C. elegans under proteotoxic stress, and its benefits depended on the cytosolic unfolded protein response-inducing transcription factor HSF-1. Taken together, our method represents an innovative geroprotector screening approach and was able to identify a class that acts by improving protein homeostasis.

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Transcriptome-based age classifiers can distinguish young versus old tissues

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Application of age classifiers to drug-induced transcriptomes finds geroprotectors

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Validation of geroprotectors in C. elegans highlights Hsp90 inhibitors

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Hsp90 inhibitors act through HSF-1 to improve health and extend lifespan

Circadian regulation of mitochondrial uncoupling and lifespan

Because old age is associated with defects in circadian rhythm, loss of circadian regulation is thought to be pathogenic and contribute to mortality. We show instead that loss of specific circadian clock components Period (Per) and Timeless (Tim) in male Drosophila significantly extends lifespan. This lifespan extension is not mediated by canonical diet-restriction longevity pathways but is due to altered cellular respiration via increased mitochondrial uncoupling. Lifespan extension of per mutants depends on mitochondrial uncoupling in the intestine. Moreover, upregulated uncoupling protein UCP4C in intestinal stem cells and enteroblasts is sufficient to extend lifespan and preserve proliferative homeostasis in the gut with age. Consistent with inducing a metabolic state that prevents overproliferation, mitochondrial uncoupling drugs also extend lifespan and inhibit intestinal stem cell overproliferation due to aging or even tumorigenesis. These results demonstrate that circadian-regulated intestinal mitochondrial uncoupling controls longevity in Drosophila and suggest a new potential anti-aging therapeutic target.

Properties, toxicity and current applications of the biolarvicide spinosad

Characterized as a highly valuable bioactive natural product, spinosad is a pesticide with a complex chemical structure, composed of spinosyn A and D, molecules synthesized by the actinomycete Saccharopolyspora spinosa. The larvicidal activity of spinosad was postulated to be a promising approach to combat crop pests and control species responsible to transmit mosquito-borne illness, including Aedes aegypti. Although initially deemed as relatively safe for non-target organisms and highly effective against insects and crop pests, recent studies focused on the toxicity profile detected the occurrence of side effects in different living species. Thus, the present review was undertaken to describe the properties and characteristics of spinosad. In addition to indicating potential adverse effects on living organisms, alternative uses of the biopesticide as a mixture with different compounds are provided.

Evolution of ageing as a tangle of trade-offs: energy versus function

Despite tremendous progress in recent years, our understanding of the evolution of ageing is still incomplete. A dominant paradigm maintains that ageing evolves due to the competing energy demands of reproduction and somatic maintenance leading to slow accumulation of unrepaired cellular damage with age. However, the centrality of energy trade-offs in ageing has been increasingly challenged as studies in different organisms have uncoupled the trade-off between reproduction and longevity. An emerging theory is that ageing instead is caused by biological processes that are optimized for early-life function but become harmful when they continue to run-on unabated in late life. This idea builds on the realization that early-life regulation of gene expression can break down in late life because natural selection is too weak to optimize it. Empirical evidence increasingly supports the hypothesis that suboptimal gene expression in adulthood can result in physiological malfunction leading to organismal senescence. We argue that the current state of the art in the study of ageing contradicts the widely held view that energy trade-offs between growth, reproduction, and longevity are the universal underpinning of senescence. Future research should focus on understanding the relative contribution of energy and function trade-offs to the evolution and expression of ageing.

Combined effects of elevated CO2 concentration and Wolbachia on Hylyphantes graminicola (Araneae: Linyphiidae)

The increasing concentration of carbon dioxide in atmosphere is not only a major cause of global warming, but it also adversely affects the ecological diversity of invertebrates. This study was conducted to evaluate the effect of elevated CO2 concentration (ambient, 400 ppm and high, 800 ppm) and Wolbachia (Wolbachia-infected, W+ and Wolbachia-uninfected, W-) on Hylyphantes graminicola. The total survival rate, developmental duration, carapace width and length, body weight, sex ratio, net reproductive rate, nutrition content, and enzyme activity in H. graminicola were examined under four treatments: W- 400 ppm, W- 800 ppm, W+ 400 ppm, and W+ 800 ppm. Results showed that Wolbachia-infected spiders had significantly decreased the total developmental duration. Different instars showed variations up to some extent, but no obvious effect was found under elevated CO2 concentration. Total survival rate, sex ratio, and net reproductive rate were not affected by elevated CO2 concentration or Wolbachia infection. The carapace width of Wolbachia-uninfected spiders decreased significantly under elevated CO2 concentration, while the width, length and weight were not significantly affected in Wolbachia-infected spiders reared at ambient CO2 concentration. The levels of protein, specific activities of peroxidase, and amylase were significantly increased under elevated CO2 concentration or Wolbachia-infected spiders, while the total amino content was only increased in Wolbachia-infected spiders. Thus, our current finding suggested that elevated CO2 concentration and Wolbachia enhance nutrient contents and enzyme activity of H. graminicola and decrease development duration hence explore the interactive effects of factors which were responsible for reproduction regulation, but it also gives a theoretical direction for spider's protection in such a dynamic environment. Increased activities of enzymes and nutrients caused by Wolbachia infection aids for better survival of H. graminicola under stress.

Aedes aegypti larvae treated with spinosad produce adults with damaged midgut and reduced fecundity

The mosquito Aedes aegypti is the main vector of Dengue, Chikungunya, Zika, and yellow fever viruses, which are responsible for high human morbidity and mortality. The fight against these pathogens is mainly based on the control of the insect vector with the use of insecticides. Among insecticides, spinosad bioinsecticide is efficient against A. aegypti larvae and may be an alternative for vector control. Here, we investigate the sublethal effects of spinosad during midgut metamorphosis of A. aegypti females and its cumulative effects on blood acquisition capacity and fecundity in adults. We studied the midgut because it is an important model organ directly related to blood acquisition and digestion. Treatment of larvae with spinosad induced oxidative stress, apoptosis, and damage to the midgut cells at all stages of development and in adults. There was a reduction in the number of proliferating cells and the number of enteroendocrine cells in treated individuals. In addition, damage caused by spinosad led to a reduction in oviposition and egg viability of A. aegypti females. Finally, the exposure of mosquito larvae to sublethal concentrations of spinosad interfered with the development of the midgut, arresting the blood digestion and reproduction of adult females with blood digestion and reproduction difficulties.

High doses of sodium ascorbate act as a prooxidant and protect gnotobiotic brine shrimp larvae (Artemia franciscana) against Vibrio harveyi infection coinciding with heat shock protein 70 activation

Ascorbate is an essential nutrient commonly regarded as an antioxidant. In this study, using axenic brine shrimp and pathogenic strain Vibrio harveyi as the host-pathogen model, we confirmed that pretreatment of sodium ascorbate (NaAs), at an optimum concentration, was a prooxidant by generation of hydrogen peroxide, inducing protective effects in the brine shrimp against V. harveyi infection. Such a protective effect could be neutralized by the addition of an antioxidant enzyme catalase. We further showed that generation of oxygen radicals is linked to the induction of heat shock protein 70 (Hsp70), which is involved in eliciting the antioxidant protection system including superoxidase dismutase (SOD) and possibly many other immune responses. Furthermore, using RNA interference technique, we found that the pretreatment of sodium ascorbate increased the survival significantly in the control knockdown groups (using green fluorescent protein, GFP) but not in Hsp70 knockdown groups and the result directly suggested that the up-regulated Hsp70 induced by sodium ascorbate pretreatment induced the protective effect. These results provide a mechanistic rationale for exploring the further use of ascorbate for antimicrobial therapy in aquaculture.

Dietary wild bitter gourd displays selective androgen receptor modulator like activity and improves the muscle decline of orchidectomized mice

Loss of skeletal muscle mass and strength is often associated with disability and poor quality of life. Selective Androgen Receptor Modulators (SARMs) are under development as potential treatment. This study aims at examining the potential of wild bitter gourd (BG) as a SARM and its effects on the muscle decline induced by orchiectomy. In the cell-based androgen receptor (AR) transactivation assay, the BGP extract showed weak agonistic and antagonistic activities, resembling those of some SARMs. Male C57BL/6J mice were sham-operated (Sham group) or castrated (Cast groups) and fed a modified AIN-93G high sucrose diet supplemented without (Cast group) or with 5% lyophilized BG powder (Cast + BGP) or with testosterone propionate (7 mg TP per kg diet, Cast + TP) for 23 weeks. In contrast to the Cast + TP group, the BGP supplementation did not affect the serum testosterone concentration, and prostate and seminal vesicle mass. Both TP and BGP supplementation increased the weight of androgen responsive muscles, bulbocavernosus (BC) and levator ani (LA) (p < 0.05). The grip strength and the performance on a rotarod of the Cast + BGP group were comparable to those of the Cast + TP group (p > 0.05). The number of succinate dehydrogenase (SDH)-positive fibers of the Cast + BGP group was not significantly different from that of the Sham and Cast + TP groups (p > 0.05). The BGP supplementation up-regulated the Pgc1α, Ucp2 or Ucp3 gene expressions in skeletal muscles of castrated mice (p < 0.05). BGP showed some characteristics of the SARM and might improve skeletal muscle function through the up-regulation of mitochondrial biogenic genes and oxidative capacity, and ameliorated the castration-induced decline of skeletal muscle function in mice.

Atg1-mediated autophagy suppresses tissue degeneration in pink1/parkin mutants by promoting mitochondrial fission in Drosophila

Mitochondrial dysfunction is considered a hallmark of multiple neurodegenerative diseases, including Parkinson’s disease (PD). The PD familial genes pink1 and parkin function in a conserved pathway that regulates mitochondrial function, including dynamics (fusion and fission). Mammalian cell culture studies suggested that the pink1/parkin pathway promotes mitophagy (mitochondrial autophagy). Mitophagy through mitochondrial fission and autolysosomal recycling was considered a quality control system at the organelle level. Whether defects in this quality control machinery lead to pathogenesis in vivo in PD remains elusive. Here, we found that elevating autophagy by atg1 overexpression can significantly rescue mitochondrial defects and apoptotic cell death in pink1 and parkin mutants in Drosophila. Surprisingly, the rescue effect relied both on the autophagy–lysosome machinery and on drp1, a mitochondrial fission molecule. We further showed that Atg1 promotes mitochondrial fission by posttranscriptional increase in the Drp1 protein level. In contrast, increasing fission (by drp1 overexpression) or inhibiting fusion (by knocking down mitofusin [mfn]) rescues pink1 mutants when lysosomal or proteasomal machinery is impaired. Taken together, our results identified Atg1 as a dual-function node that controls mitochondrial quality by promoting mitochondria fission and autophagy, which makes it a potential therapeutic target for treatment of mitochondrial dysfunction–related diseases, including PD.

A Ketogenic Diet Improves Mitochondrial Biogenesis and Bioenergetics via the PGC1α-SIRT3-UCP2 Axis

A ketogenic diet (KD; high-fat, low-carbohydrate) can benefit refractory epilepsy, but underlying mechanisms are unknown. We used mice inducibly expressing a mutated form of the mitochondrial DNA repair enzyme UNG1 (mutUNG1) to cause progressive mitochondrial dysfunction selectively in forebrain neurons. We examined the levels of mRNAs and proteins crucial for mitochondrial biogenesis and dynamics. We show that hippocampal pyramidal neurons in mutUNG1 mice, as well as cultured rat hippocampal neurons and human fibroblasts with H₂O₂ induced oxidative stress, improve markers of mitochondrial biogenesis, dynamics and function when fed on a KD, and when exposed to the ketone body β-hydroxybutyrate, respectively, by upregulating PGC1α, SIRT3 and UCP2, and (in cultured cells) increasing the oxygen consumption rate (OCR) and the NAD⁺/NADH ratio. The mitochondrial level of UCP2 was significantly higher in the perikarya and axon terminals of hippocampus CA1 pyramidal neurons in KD treated mutUNG1 mice compared with mutUNG1 mice fed a standard diet. The β-hydroxybutyrate receptor GPR109a (HCAR2), but not the structurally closely related lactate receptor GPR81 (HCAR1), was upregulated in mutUNG1 mice on a KD, suggesting a selective influence of KD on ketone body receptor mechanisms. We conclude that progressive mitochondrial dysfunction in mutUNG1 expressing mice causes oxidative stress, and that exposure of animals to KD, or of cells to ketone body in vitro, elicits compensatory mechanisms acting to augment mitochondrial mass and bioenergetics via the PGC1α-SIRT3-UCP2 axis (The compensatory processes are overwhelmed in the mutUNG1 mice by all the newly formed mitochondria being dysfunctional).

The emerging role of immune dysfunction in mitochondrial diseases as a paradigm for understanding immunometabolism

Immunometabolism aims to define the role of intermediary metabolism in immune cell function, with bioenergetics and the mitochondria recently taking center stage. To date, the medical literature on mitochondria and immune function extols the virtues of mouse models in exploring this biologic intersection. While the laboratory mouse has become a standard for studying mammalian biology, this model comprises part of a comprehensive approach. Humans, with their broad array of inherited phenotypes, serve as a starting point for studying immunometabolism; specifically, patients with mitochondrial disease. Using this top-down approach, the mouse as a model organism facilitates further exploration of the consequences of mutations involved in mitochondrial maintenance and function. In this review, we will discuss the emerging phenotype of immune dysfunction in mitochondrial disease as a model for understanding the role of the mitochondria in immune function in available mouse models.

Sex differences in brain mitochondrial metabolism: influence of endogenous steroids and stroke

Steroids are neuroprotective and a growing body of evidence indicates that mitochondria are a potential target of their effects. The mitochondria are the site of cellular energy synthesis, regulate oxidative stress and play a key role in cell death after brain injury and neurodegenerative diseases. After providing a summary of the literature on the general functions of mitochondria and the effects of sex steroid administrations on mitochondrial metabolism, we summarise and discuss our recent findings concerning sex differences in brain mitochondrial function under physiological and pathological conditions. To analyse the influence of endogenous sex steroids, the oxidative phosphorylation system, mitochondrial oxidative stress and brain steroid levels were compared between male and female mice, either intact or gonadectomised. The results obtained show that females have higher a mitochondrial respiration and lower oxidative stress compared to males and also that these differences were suppressed by ovariectomy but not orchidectomy. We have also shown that the decrease in brain mitochondrial respiration induced by ischaemia/reperfusion is different according to sex. In both sexes, treatment with progesterone reduced the ischaemia/reperfusion-induced mitochondrial alterations. Our findings indicate sex differences in brain mitochondrial function under physiological conditions, as well as after stroke, and identify mitochondria as a target of the neuroprotective properties of progesterone. Thus, it is necessary to investigate sex specificity in brain physiopathological mechanisms, especially when mitochondria impairment is involved.

Hypothalamic stem cells control ageing speed partly through exosomal miRNAs

Hypothalamic control of aging was recently proposed, but the responsible mechanisms still remain unclear. Here, following the observation that aging of mice started with a substantial loss of hypothalamic stem/progenitor cells that co-express Sox2 and Bmi1, we developed several mouse models with ablation of these hypothalamic cells, each of them consistently displaying an acceleration in aging-like physiological changes or shortening in lifespan. Conversely, aging retardation and lifespan extension were achieved in mid-aged mice when locally implanted with healthy hypothalamic stem/progenitor cells that were genetically engineered to survive from aging-related hypothalamic inflammatory microenvironment. Mechanistically, hypothalamic stem/progenitor cells greatly contributed to exosomal miRNAs in the cerebrospinal fluid which declined over aging, while central treatment with healthy hypothalamic stem/progenitor cells-secreted exosomes led to slowdown of aging. In conclusion, aging speed is controlled significantly by hypothalamic stem cells partially through release of exosomal miRNAs.

Uncoupling protein 2 and metabolic diseases

Mitochondria are fascinating organelles involved in various cellular-metabolic activities that are integral for mammalian development. Although they perform diverse, yet interconnected functions, mitochondria are remarkably regulated by complex signaling networks. Therefore, it is not surprising that mitochondrial dysfunction is involved in plethora of diseases, including neurodegenerative and metabolic disorders. One of the many factors that lead to mitochondrial-associated metabolic diseases is the uncoupling protein-2, a family of mitochondrial anion proteins present in the inner mitochondrial membrane. Since their discovery, uncoupling proteins have attracted considerable attention due to their involvement in mitochondrial-mediated oxidative stress and energy metabolism. This review attempts to provide a summary of recent developments in the field of uncoupling protein 2 relating to mitochondrial associated metabolic diseases.

Enhanced resistance against Vibrio harveyi infection by carvacrol and its association with the induction of heat shock protein 72 in gnotobiotic Artemia franciscana

Induction of HSP72 is a natural response of stressed organisms that protects against many insults including bacterial diseases in farm (aquatic) animals. It would therefore be of great health benefit to search for natural compounds that are clinically safe yet able to induce HSP72 in animals. The phenolic compound carvacrol, an approved food component, had been shown in in vitro study to act as a co-inducer of HSP72, enhancing HSP72 production only in combination with a bona fide stress compared to the compound alone. However, in vitro model systems do not completely represent an in vivo physiology. Here, using the well-established gnotobiotic Artemia model system, we determined whether carvacrol could induce HSP72 in vivo, whether this putative effect could generate resistance in Artemia against biotic/abiotic stress and also unraveled the mechanism behind the possible HSP72-inducing effect of carvacrol. The gnotobiotic system is crucial for such studies because it avoids the interference of any extraneous factors on host-compound interaction. Here, carvacrol was shown to be a potent HSP72 inducer. Induction of HSP72 was associated with the generation of resistance in Artemia larvae against subsequent lethal heat stress or pathogenic Vibrio harveyi. Our results also provided new insight on the mode of HSP72 inducing action of carvacrol, in which the initial generation of reactive molecule H2O2 by the compound plays a key role. Overall results add new information about the bioactivity of carvacrol and advance our knowledge of this compound as potential prophylactic agent for controlling Vibrio infection in aquaculture animals.

The Mitochondria-Targeted Plastoquinone-Derivative SkQ1 Promotes Health and Increases Drosophila melanogaster Longevity in Various Environments

Mitochondria play an important role in aging. Strongly reduced function of the mitochondria shortens life span, whereas moderate reduction prolongs life span, with reactive oxygen species production being the major factor contributing to life span changes. Previously, picomolar concentrations of the mitochondria-targeted antioxidant SkQ1 were shown to increase the life span of Drosophila by approximately 10%. In this article, we demonstrate that SkQ1 elevates locomotion, which is often considered a marker of health and age. We also show that mating frequency and fecundity may be slightly increased in SkQ1-treated flies. These results indicate that SkQ1 not only prolongs life span but also improves health and vigor. An important property of any potential therapeutic is the stability of its effects in an uncontrolled and changing environment as well as on individuals with various genetic constitutions. In this article, we present data on SkQ1 effects on Drosophila longevity in extreme environments (low temperatures and starvation) and on individuals with severe genetic alterations in the mitochondrial systems responsible for production and detoxification of reactive oxygen species. We hypothesize that in vivo SkQ1 is capable of alleviating the probable negative effects of increased mitochondrial reactive oxygen species production on longevity but is not effective when reactive oxygen species production is already reduced by other means.

Mitochondrial Uncoupling Protein 2 in human cumulus cells is associated with regulating autophagy and apoptosis, maintaining gap junction integrity and progesterone synthesis

To explore the roles of mitochondrial Uncoupling Protein 2 (UCP2) in cumulus cells (CCs), human CCs were cultured in vitro, and the UCP2 was inhibited by treatment with Genipin, a special UCP inhibitor, or by RNA interference targeting UCP2. No significant differences in adenosine triphosphate levels and the ratio of ADP/ATP were observed after UCP2 inhibition. UCP2 inhibition caused a significant increase in cellular oxidative damage, which was reflected in alterations to several key parameters, including reactive oxygen species (ROS) and lipid peroxidation levels and the ratio of reduced GSH to GSSG. UCP2 blocking resulted in an obvious increase in active Caspase-3, accompanied by the decline of proactive Caspase-3 and a significant increase in the LC3-II/LC3-I ratio, suggesting that UCP2 inhibition triggered cellular apoptosis and autophagy. The mRNA and protein expression of connexin 43 (Cx43), a gap junction channel protein, were significantly reduced after treatment with Genipin or siRNA. The progesterone level in the culture medium was also significantly decreased after UCP2 inhibition. Our data indicated that UCP2 plays highly important roles in mediating ROS production and regulating apoptosis and autophagy, as well as maintaining gap junction integrity and progesterone synthesis, which suggests that UCP2 is involved in the regulation of follicle development and early embryo implantation and implies that it might serve as a potential biomarker for oocyte quality and competency.

Tissue-specific down-regulation of S-adenosyl-homocysteine via suppression of dAhcyL1/dAhcyL2 extends health span and life span in Drosophila

Methionine generates the methyl donor SAM, which is converted via methylation to SAH, which accumulates during aging. Parkhitko et al. discovered significant life span extension in response to down-regulation of two noncanonical Drosophila homologs of the SAH hydrolase Ahcy, CG9977/dAhcyL1 and Ahcy89E/CG8956/dAhcyL2, which act as dominant-negative regulators of canonical AHCY. Tissue-specific down-regulation of dAhcyL1/L2 in the brain and intestine extends health and life span.

Aging is a risk factor for many human pathologies and is characterized by extensive metabolic changes. Using targeted high-throughput metabolite profiling in Drosophila melanogaster at different ages, we demonstrate that methionine metabolism changes strikingly during aging. Methionine generates the methyl donor S-adenosyl-methionine (SAM), which is converted via methylation to S-adenosyl-homocysteine (SAH), which accumulates during aging. A targeted RNAi screen against methionine pathway components revealed significant life span extension in response to down-regulation of two noncanonical Drosophila homologs of the SAH hydrolase Ahcy (S-adenosyl-L-homocysteine hydrolase [SAHH[), CG9977/dAhcyL1 and Ahcy89E/CG8956/dAhcyL2, which act as dominant-negative regulators of canonical AHCY. Importantly, tissue-specific down-regulation of dAhcyL1/L2 in the brain and intestine extends health and life span. Furthermore, metabolomic analysis of dAhcyL1-deficient flies revealed its effect on age-dependent metabolic reprogramming and H3K4 methylation. Altogether, reprogramming of methionine metabolism in young flies and suppression of age-dependent SAH accumulation lead to increased life span. These studies highlight the role of noncanonical Ahcy enzymes as determinants of healthy aging and longevity.

The gnotobiotic brine shrimp (Artemia franciscana) model system reveals that the phenolic compound pyrogallol protects against infection through its prooxidant activity

The phenolic compound pyrogallol is the functional unit of many polyphenols and currently there has been a growing interest in using this compound in human and animal health owing to its health-promoting effects. The biological actions of pyrogallol moiety (and polyphenols) in inducing health benefitting effects have been studied; however, the mechanisms of action remain unclear yet. Here, we aimed at unravelling the underlying mechanism of action behind the protective effects of pyrogallol against bacterial infection by using the gnotobiotically-cultured brine shrimp Artemia franciscana and pathogenic bacteria Vibrio harveyi as host-pathogen model system. The gnotobiotic test system represents an exceptional system for carrying out such studies because it eliminates any possible interference of microbial communities (naturally present in the experimental system) in mechanistic studies and furthermore facilitates the interpretation of the results in terms of a cause effect relationship. We provided clear evidences suggesting that pyrogallol pretreament, at an optimum concentration, induced protective effects in the brine shrimp against V. harveyi infection. By pretreating brine shrimp with pyrogallol in the presence or absence of an antioxidant enzyme mixture (catalase and superoxide dismutase), we showed that the Vibrio-protective effect of the compound was caused by its prooxidant action (e.g. generation of hydrogen peroxide, H2O2). We showed further that generation of prooxidant is linked to the induction of heat shock protein Hsp70, which is involved in eliciting the prophenoloxidase and transglutaminase immune responses. The ability of pyrogallol to induce protective immunity makes it a potential natural protective agent that might be a potential preventive modality for different host-pathogen systems.

Nmdmc overexpression extends Drosophila lifespan and reduces levels of mitochondrial reactive oxygen species

NAD-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase (NMDMC) is a bifunctional enzyme involved in folate-dependent metabolism and highly expressed in rapidly proliferating cells. However, Nmdmc physiological roles remain unveiled. We found that ubiquitous Nmdmc overexpression enhanced Drosophila lifespan and stress resistance. Interestingly, Nmdmc overexpression in the fat body was sufficient to increase lifespan and tolerance against oxidative stress. In addition, these conditions coincided with significant decreases in the levels of mitochondrial ROS and Hsp22 as well as with a significant increase in the copy number of mitochondrial DNA. These results suggest that Nmdmc overexpression should be beneficial for mitochondrial homeostasis and increasing lifespan.

Tequila Regulates Insulin-Like Signaling and Extends Life Span in Drosophila melanogaster

The aging process is a universal phenomenon shared by all living organisms. The identification of longevity genes is important in that the study of these genes is likely to yield significant insights into human senescence. In this study, we have identified Tequila as a novel candidate gene involved in the regulation of longevity in Drosophila melanogaster. We have found that a hypomorphic mutation of Tequila (Teq(f01792)), as well as cell-specific downregulation of Tequila in insulin-producing neurons of the fly, significantly extends life span. Tequila deficiency-induced life-span extension is likely to be associated with reduced insulin-like signaling, because Tequila mutant flies display several common phenotypes of insulin dysregulation, including reduced circulating Drosophila insulin-like peptide 2 (Dilp2), reduced Akt phosphorylation, reduced body size, and altered glucose homeostasis. These observations suggest that Tequila may confer life-span extension by acting as a modulator of Drosophila insulin-like signaling.

Differential modulation of AMPK/PPARα/UCP2 axis in relation to hypertension and aging in the brain, kidneys and heart of two closely related spontaneously hypertensive rat strains

OBJECTIVES

We examined expression protein of AMPK/SIRT1/PGC1α/PhoxO3a/PPARα/UCP2 pathway in brain, kidneys and heart of stroke-prone spontaneously hypertensive rat (SHRSP) vs stroke-resistant SHR (SHRSR) at different weeks of age, up to one year, in order to test the hypothesis that abnormalities within this pathway could associate with higher susceptibility of SHRSP to develop hypertension-related vascular damage.

BACKGROUND

SHRSP develops severe hypertension and related target organ damage. Marked reduction of uncoupling protein 2 (UCP2) expression upon high salt-low potassium diet associates with increased renal injury in SHRSP. UCP2 may represent a key mitochondrial protein involved in cardiovascular damage.

RESULTS

At 2 months of age a significant down-regulation of UCP2 expression at both mRNA and protein levels was found, along with reduced protein expression of all components of UCP2 regulatory pathway, in tissues of SHRSP but not of SHRSR, that progressed with hypertension development and aging. A significant increase of both oxidative stress and inflammation was detected in tissues of SHRSP as a function of age. SBP levels were significantly higher in SHRSP than SHRSR at 3 months of age and thereafter. At one year of age, higher degree of renal damage, with proteinuria and severe glomerular and tubulo-interstitial fibrosis, of cerebral damage, with significant vessel extravasation and stroke occurrence, and of myocardial damage was detected in SHRSP than SHRSR. 

CONCLUSIONS

The early significant reduced expression of the antioxidant AMPK/PPARα/UCP2 pathway that progressed throughout lifetime may contribute to explain higher predisposition of SHRSP to oxidative stress dependent target organ damage in the context of severe hypertension.

A transcriptional reporter of intracellular Ca(2+) in Drosophila

Intracellular Ca²⁺ is a widely used neuronal activity indicator. Here we describe a transcriptional reporter of intracellular Ca²⁺ (TRIC) in Drosophila, which uses a binary expression system to report Ca²⁺-dependent interactions between calmodulin and its target peptide. We show that in vitro assays predict in vivo properties of TRIC, and that TRIC signals in sensory systems depend on neuronal activity. TRIC can quantitatively monitor neuronal responses that change slowly, such as those of neuropeptide F-expressing neurons to sexual deprivation and neuroendocrine pars intercerebralis (PI) cells to food and arousal. Furthermore, TRIC-induced expression of a neuronal silencer in nutrient activated cells enhanced stress resistance, providing proof-of-principle that TRIC can be used for circuit manipulation. Thus, TRIC facilitates the monitoring and manipulation of neuronal activity, especially those reflecting slow changes in physiological states that are poorly captured by existing methods. TRIC’s modular design should enable optimization and adaptation to other organisms.

Oxidative stress correlates with Wolbachia-mediated antiviral protection in Wolbachia-Drosophila associations

Wolbachia mediates antiviral protection in insect hosts and is being developed as a potential biocontrol agent to reduce the spread of insect-vectored viruses. Definition of the molecular mechanism that generates protection is important for understanding the tripartite interaction between host insect, Wolbachia, and virus. Elevated oxidative stress was previously reported for a mosquito line experimentally infected with Wolbachia, suggesting that oxidative stress is important for Wolbachia-mediated antiviral protection. However, Wolbachia experimentally introduced into mosquitoes impacts a range of host fitness traits, some of which are unrelated to antiviral protection. To explore whether elevated oxidative stress is associated with antiviral protection in Wolbachia-infected insects, we analyzed oxidative stress of five Wolbachia-infected Drosophila lines. In flies infected with protective Wolbachia strains, hydrogen peroxide concentrations were 1.25- to 2-fold higher than those in paired fly lines cured of Wolbachia infection. In contrast, there was no difference in the hydrogen peroxide concentrations in flies infected with nonprotective Wolbachia strains compared to flies cured of Wolbachia infection. Using a Drosophila mutant that produces increased levels of hydrogen peroxide, we investigated whether flies with high levels of endogenous reactive oxygen species had altered responses to virus infection and found that flies with high levels of endogenous hydrogen peroxide were less susceptible to virus-induced mortality. Taken together, these results suggest that elevated oxidative stress correlates with Wolbachia-mediated antiviral protection in natural Drosophila hosts.

Resveratrol regulates mitochondrial reactive oxygen species homeostasis through Sirt3 signaling pathway in human vascular endothelial cells

Mitochondrial reactive oxygen species (mtROS) homeostasis plays an essential role in preventing oxidative injury in endothelial cells, an initial step in atherogenesis. Resveratrol (RSV) possesses a variety of cardioprotective activities, however, little is known regarding the effects of RSV on mtROS homeostasis in endothelial cells. Sirt3 is a mitochondrial deacetylase, which plays a key role in mitochondrial bioenergetics and is closely associated with oxidative stress. The goal of the study is to investigate whether RSV could attenuate oxidative injury in endothelial cells via mtROS homeostasis regulation through Sirt3 signaling pathway. We found that pretreatment with RSV suppressed tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in human umbilical vein endothelial cells (HUVECs) by increasing cell viability, inhibiting cell apoptosis, repressing collapse of mitochondrial membrane potential and decreasing mtROS generation. Moreover, the enzymatic activities of isocitrate dehydrogenase 2 (IDH2), glutathione peroxidase (GSH-Px) and manganese superoxide dismutase (SOD2) as well as deacetylation of SOD2 were increased by RSV pretreatment, suggesting RSV notably enhanced mtROS scavenging in t-BHP-induced endothelial cells. Meanwhile, RSV remarkably reduced mtROS generation by promoting Sirt3 enrichment within the mitochondria and subsequent upregulation of forkhead box O3A (FoxO3A)-mediated mitochondria-encoded gene expression of ATP6, CO1, Cytb, ND2 and ND5, thereby leading to increased complex I activity and ATP synthesis. Furthermore, RSV activated the expressions of phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and Sirt3, as well as estrogen-related receptor-α (ERRα)-dependent Sirt3 mRNA transcription, which were abolished in the presence of AMPK inhibitor and AMPK, PGC-1α or Sirt3 siRNA transfection, indicating the effects of RSV on mtROS homeostasis regulation were dependent on AMPK-PGC-1α-ERRα-Sirt3 signaling pathway. Our findings indicated a novel mechanism that RSV-attenuated oxidative injury in endothelial cells through the regulation of mtROS homeostasis, which, in part, was mediated through the activation of the Sirt3 signaling pathway.

Perspectives on mitochondrial uncoupling proteins-mediated neuroprotection

The integrity of mitochondrial function is essential to cell life. It follows that disturbances of mitochondrial function will lead to disruption of cell function, expressed as disease or even death. Considering that neuronal uncoupling proteins (UCPs) decrease reactive oxygen species (ROS) production at the expense of energy production, it is important to understand the underlying mechanisms by which UCPs control the balance between the production of adenosine triphosphate (ATP) and ROS in the context of normal physiological activity and in pathological conditions. Here we review the current understanding of neuronal UCPs-mediated respiratory uncoupling process by performing a survey in their physiology and regulation. The latest findings regarding neuronal UCPs physiological roles and their involvement and interest as potential targets for therapeutic intervention in brain diseases will also be exploited.

A genetic strategy to measure circulating Drosophila insulin reveals genes regulating insulin production and secretion

Insulin is a major regulator of metabolism in metazoans, including the fruit fly Drosophila melanogaster. Genome-wide association studies (GWAS) suggest a genetic basis for reductions of both insulin sensitivity and insulin secretion, phenotypes commonly observed in humans with type 2 diabetes mellitus (T2DM). To identify molecular functions of genes linked to T2DM risk, we developed a genetic tool to measure insulin-like peptide 2 (Ilp2) levels in Drosophila, a model organism with superb experimental genetics. Our system permitted sensitive quantification of circulating Ilp2, including measures of Ilp2 dynamics during fasting and re-feeding, and demonstration of adaptive Ilp2 secretion in response to insulin receptor haploinsufficiency. Tissue specific dissection of this reduced insulin signaling phenotype revealed a critical role for insulin signaling in specific peripheral tissues. Knockdown of the Drosophila orthologues of human T2DM risk genes, including GLIS3 and BCL11A, revealed roles of these Drosophila genes in Ilp2 production or secretion. Discovery of Drosophila mechanisms and regulators controlling in vivo insulin dynamics should accelerate functional dissection of diabetes genetics.

Mitochondrial proteostasis in the control of aging and longevity

Mitochondria play a central role in the aging process. Studies in model organisms have started to integrate mitochondrial effects on aging with the maintenance of protein homeostasis. These findings center on the mitochondrial unfolded protein response (UPR(mt)), which has been implicated in lifespan extension in worms, flies, and mice, suggesting a conserved role in the long-term maintenance of cellular homeostasis. Here, we review current knowledge of the UPR(mt) and discuss its integration with cellular pathways known to regulate lifespan. We highlight how insight into the UPR(mt) is revolutionizing our understanding of mitochondrial lifespan extension and of the aging process.