Effects of caffeine on metabolism and mitochondria biogenesis in rhabdomyosarcoma cells compared with 2,4-dinitrophenol

Impact of coffee intake on human aging: Epidemiology and cellular mechanisms

The conception of coffee consumption has undergone a profound modification, evolving from a noxious habit into a safe lifestyle actually preserving human health. The last 20 years also provided strikingly consistent epidemiological evidence showing that the regular consumption of moderate doses of coffee attenuates all-cause mortality, an effect observed in over 50 studies in different geographic regions and different ethnicities. Coffee intake attenuates the major causes of mortality, dampening cardiovascular-, cerebrovascular-, cancer- and respiratory diseases-associated mortality, as well as some of the major causes of functional deterioration in the elderly such as loss of memory, depression and frailty. The amplitude of the benefit seems discrete (17 % reduction) but nonetheless corresponds to an average increase in healthspan of 1.8 years of lifetime. This review explores evidence from studies in humans and human tissues supporting an ability of coffee and of its main components (caffeine and chlorogenic acids) to preserve the main biological mechanisms responsible for the aging process, namely genomic instability, macromolecular damage, metabolic and proteostatic impairments with particularly robust effects on the control of stress adaptation and inflammation and unclear effects on stem cells and regeneration. Further studies are required to detail these mechanistic benefits in aged individuals, which may offer new insights into understanding of the biology of aging and the development of new senostatic strategies. Additionally, the safety of this lifestyle factor in the elderly prompts a renewed attention to recommending the maintenance of coffee consumption throughout life as a healthy lifestyle and to further exploring who gets the greater benefit with what schedules of which particular types and doses of coffee.

Alzheimer's disease approaches - Focusing on pathology, biomarkers and clinical trial candidates

The strategy for the development of new drugs for Alzheimer's disease (AD) recognizes that an effective therapy requires early therapeutic intervention and a multifactorial approach that considers the individual initiators of AD development. Current knowledge of AD includes the understanding of pathophysiology, risk factors, biomarkers, and the evolving patterns of biomarker abnormalities. This knowledge is essential in identifying potential molecular targets for new drug development. This review summarizes promising AD drug candidates, many of which are currently in phase 2 or 3 clinical trials. New agents are classified according to the Common Alzheimer's Disease Research Ontology (CADRO). The main targets of new drugs for AD are processes related to amyloid beta and tau neurotoxicity, neurotransmission, inflammation, metabolism and bioenergetics, synaptic plasticity, and oxidative stress. These interventions are aimed at preventing disease onset and slowing or eliminating disease progression. The efficacy of pharmacotherapy may be enhanced by combining these drugs with other treatments, antioxidants, and dietary supplements. Ongoing research into AD pathophysiology, risk factors, biomarkers, and the dynamics of biomarker abnormalities may contribute to the understanding of AD and offer hope for effective therapeutic strategies in the near future.

Protective effects of 2,4-dinitrophenol in okadaic acid-induced cellular model of Alzheimer's disease

Alzheimer's disease (AD) research started several decades ago and despite the many efforts employed to develop new treatments or approaches to slow and/or revert disease progression, AD treatment remains an unsolved issue. Knowing that mitochondria loss of function is a central hub for many AD-associated pathophysiological processes, there has been renewed interest in exploring mitochondria as targets for intervention. In this perspective, the present study was aimed to investigate the possible beneficial effects of 2,4 dinitrophenol (DNP), a mitochondrial uncoupler agent, in an in vitro model of AD. Retinoic acid-induced differentiated SH-SY5Y cells were incubated with okadaic acid (OA), a neurotoxin often used as an AD experimental model, and/or with DNP. OA caused a decrease in neuronal cells viability, induced multiple mitochondrial anomalies including increased levels of reactive oxygen species, decreased bioenergetics and mitochondria content markers, and an altered mitochondria morphology. OA-treated cells also presented increased lipid peroxidation levels, and overactivation of tau related kinases (GSK3β, ERK1/2 and AMPK) alongside with a significant augment in tau protein phosphorylation levels. Interestingly, DNP co-treatment ameliorated and rescued OA-induced detrimental effects not only on mitochondria but also but also reinstated signaling pathways homeostasis and ameliorated tau pathology. Overall, our results show for the first time that DNP has the potential to preserve mitochondria homeostasis under a toxic insult, like OA exposure, as well as to reestablish cellular signaling homeostasis. These observations foster the idea that DNP, as a mitochondrial modulator, might represent a new avenue for treatment of AD.

Caffeine: a potential mechanism for anti-obesity

Obesity refers to the excessive accumulation of fat caused by a long-term imbalance between energy intake (EI) and energy expenditure (EE). Over recent years, obesity has become a major public health challenge. Caffeine is a natural product that has been demonstrated to exert anti-obesity effects; however, the mechanisms responsible for the effect of caffeine on weight loss have yet to be fully elucidated. Most obesity-related deaths are due to cardiovascular disease. Recent research has demonstrated that caffeine can reduce the risk of death from cardiovascular disease; thus, it can be hypothesized that caffeine may represent a new therapeutic agent for weight loss. In this review, we synthesize data arising from clinical and animal studies over the last decade and discuss the potential mechanisms by which caffeine may induce weight loss, focusing particularly on increasing energy consumption, suppressing appetite, altering lipid metabolism, and influencing the gut microbiota. Finally, we summarize the major challenges associated with caffeine and anti-obesity research and highlight possible directions for future research and development.

Mitochondrial stress: a key role of neuroinflammation in stroke

Stroke is a clinical syndrome characterized by an acute, focal neurological deficit, primarily caused by the occlusion or rupture of cerebral blood vessels. In stroke, neuroinflammation emerges as a pivotal event contributing to neuronal cell death. The occurrence and progression of neuroinflammation entail intricate processes, prominently featuring mitochondrial dysfunction and adaptive responses. Mitochondria, a double membrane-bound organelle are recognized as the "energy workshop" of the body. Brain is particularly vulnerable to mitochondrial disturbances due to its high energy demands from mitochondria-related energy production. The interplay between mitochondria and neuroinflammation plays a significant role in the pathogenesis of stroke. The biological and pathological consequences resulting from mitochondrial stress have substantial implications for cerebral function. Mitochondrial stress serves as an adaptive mechanism aimed at mitigating the stress induced by the import of misfolded proteins, which occurs in response to stroke. This adaptive response involves a reduction in misfolded protein accumulation and overall protein synthesis. The influence of mitochondrial stress on the pathological state of stroke is underscored by its capacity to interact with neuroinflammation. The impact of mitochondrial stress on neuroinflammation varies according to its severity. Moderate mitochondrial stress can bolster cellular adaptive defenses, enabling cells to better withstand detrimental stressors. In contrast, sustained and excessive mitochondrial stress detrimentally affects cellular and tissue integrity. The relationship between neuroinflammation and mitochondrial stress depends on the degree of mitochondrial stress present. Understanding its role in stroke pathogenesis is instrumental in excavating the novel treatment of stroke. This review aims to provide the evaluation of the cross-talk between mitochondrial stress and neuroinflammation within the context of stroke. We aim to reveal how mitochondrial stress affects neuroinflammation environment in stroke.

Effects of photobiomodulation and caffeine treatment on acute kidney injury in a hypoxic ischemic neonatal rat model

Hypoxic ischemic encephalopathy (HIE) occurs in 2-5/1000 births, with acute kidney injury (AKI) occurring in 40%. AKI increases morbidity and mortality. Caffeine, an adenosine receptor antagonist, and photobiomodulation (PBM), working on cytochrome c oxidase, are potential treatments for AKI. To examine effects of caffeine and PBM on AKI in rats, Day 7 pups underwent a HIE intervention (Modified Rice-Vannucci model) replicating pathology observed in humans. Caffeine was administered for 3 days and/or PBM for 5 days following HIE. Weights and urine for biomarkers (NGAL, albumin, KIM-1, osteopontin) were collected prior to HIE, daily post intervention and at sacrifice. Both treatments reduced kidney injury seen on electron microscopy, but not when combined. HIE elevated urinary NGAL and albumin on Days 1-3 post-HIE, before returning to control levels. This elevation was significantly reduced by PBM or caffeine. KIM-1 was significantly elevated for 7 days post-HIE and was reduced by both treatments. Osteopontin was not altered by HIE or the treatments. Treatments, individually but not in combination, improved HIE-induced reductions in the enzymatic activity of mitochondrial complexes II-III. PBM and caffeine also improved weight gain. PBM and caffeine reduces AKI diagnosed by urinary biomarkers and confirmed by EM findings.

Caffeine improves mitochondrial function in PINK1B9-null mutant Drosophila melanogaster

Mitochondrial dysfunction plays a central role in Parkinson's disease (PD) and can be triggered by xenobiotics and mutations in mitochondrial quality control genes, such as the PINK1 gene. Caffeine has been proposed as a secondary treatment to relieve PD symptoms mainly by its antagonistic effects on adenosine receptors (ARs). Nonetheless, the potential protective effects of caffeine on mitochondrial dysfunction could be a strategy in PD treatment but need further investigation. In this study, we used high-resolution respirometry (HRR) to test caffeine's effects on mitochondrial dysfunction in PINK1^B9-null mutants of Drosophila melanogaster. PINK1 loss-of-function induced mitochondrial dysfunction in PINK1^B9-null flies observed by a decrease in O₂ flux related to oxidative phosphorylation (OXPHOS) and electron transfer system (ETS), respiratory control ratio (RCR) and ATP synthesis compared to control flies. Caffeine treatment improved OXPHOS and ETS in PINK^B9-null mutant flies, increasing the mitochondrial O₂ flux compared to untreated PINK^B9-null mutant flies. Moreover, caffeine treatment increased O₂ flux coupled to ATP synthesis and mitochondrial respiratory control ratio (RCR) in PINK 1^B9-null mutant flies. The effects of caffeine on respiratory parameters were abolished by rotenone co-treatment, suggesting that caffeine exerts its beneficial effects mainly by stimulating the mitochondrial complex I (CI). In conclusion, we demonstrate that caffeine may improve mitochondrial function by increasing mitochondrial OXPHOS and ETS respiration in the PD model using PINK1 loss-of-function mutant flies.

Linking the Amyloid, Tau, and Mitochondrial Hypotheses of Alzheimer's Disease and Identifying Promising Drug Targets

Damage or loss of brain cells and impaired neurochemistry, neurogenesis, and synaptic and nonsynaptic plasticity of the brain lead to dementia in neurodegenerative diseases, such as Alzheimer's disease (AD). Injury to synapses and neurons and accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles are considered the main morphological and neuropathological features of AD. Age, genetic and epigenetic factors, environmental stressors, and lifestyle contribute to the risk of AD onset and progression. These risk factors are associated with structural and functional changes in the brain, leading to cognitive decline. Biomarkers of AD reflect or cause specific changes in brain function, especially changes in pathways associated with neurotransmission, neuroinflammation, bioenergetics, apoptosis, and oxidative and nitrosative stress. Even in the initial stages, AD is associated with Aβ neurotoxicity, mitochondrial dysfunction, and tau neurotoxicity. The integrative amyloid-tau-mitochondrial hypothesis assumes that the primary cause of AD is the neurotoxicity of Aβ oligomers and tau oligomers, mitochondrial dysfunction, and their mutual synergy. For the development of new efficient AD drugs, targeting the elimination of neurotoxicity, mutual potentiation of effects, and unwanted protein interactions of risk factors and biomarkers (mainly Aβ oligomers, tau oligomers, and mitochondrial dysfunction) in the early stage of the disease seems promising.

Assessment of caffeine neurotoxicity using novel biomarkers of neural function in SH-SY5Y cells - Is there a need for environmental concern?

Worldwide usage of caffeine results in its constant release into the aquatic environment and growing concerns related to associated risks. We assessed (neuro)toxicity of environmentally relevant concentrations of caffeine, using novel biomarkers of neural function in SH-SY5Y cells and markers of general toxicity also in HepG2 cells. The RQ-PCR analyses showed that caffeine disturbs the expression of genes encoding several key elements of neurotransmitter pathways, with the most prominent responses observed for serotonin receptor 3A, dopamine receptor D2, monoamine oxidase B and GABA-transaminase. Expression of genes encoding synaptotagmin 10 involved in exocytosis of neurotransmitters and ATPase Na⁺/K⁺ transporting subunit alpha 3 was also disturbed. Caffeine stimulated the activity of monoamine oxidase, while cytotoxicity and effects on mitochondrial membrane potential were not observed. Our study points out the new possible molecular targets of caffeine and suggests that the raising concerns related to its growing environmental presence are justified.

Mitochondrial complex I as a therapeutic target for Alzheimer's disease

Alzheimer's disease (AD), the most prominent form of dementia in the elderly, has no cure. Strategies focused on the reduction of amyloid beta or hyperphosphorylated Tau protein have largely failed in clinical trials. Novel therapeutic targets and strategies are urgently needed. Emerging data suggest that in response to environmental stress, mitochondria initiate an integrated stress response (ISR) shown to be beneficial for healthy aging and neuroprotection. Here, we review data that implicate mitochondrial electron transport complexes involved in oxidative phosphorylation as a hub for small molecule-targeted therapeutics that could induce beneficial mitochondrial ISR. Specifically, partial inhibition of mitochondrial complex I has been exploited as a novel strategy for multiple human conditions, including AD, with several small molecules being tested in clinical trials. We discuss current understanding of the molecular mechanisms involved in this counterintuitive approach. Since this strategy has also been shown to enhance health and life span, the development of safe and efficacious complex I inhibitors could promote healthy aging, delaying the onset of age-related neurodegenerative diseases.

Down syndrome is an oxidative phosphorylation disorder

Down syndrome is the most common genomic disorder of intellectual disability and is caused by trisomy of chromosome 21. Several genes in this chromosome repress mitochondrial biogenesis. The goal of this study was to evaluate whether early overexpression of these genes may cause a prenatal impairment of oxidative phosphorylation negatively affecting neurogenesis. Reduction in the mitochondrial energy production and a lower mitochondrial function have been reported in diverse tissues or cell types, and also at any age, including early fetuses, suggesting that a defect in oxidative phosphorylation is an early and general event in Down syndrome individuals. Moreover, many of the medical conditions associated with Down syndrome are also frequently found in patients with oxidative phosphorylation disease. Several drugs that enhance mitochondrial biogenesis are nowadays available and some of them have been already tested in mouse models of Down syndrome restoring neurogenesis and cognitive defects. Because neurogenesis relies on a correct mitochondrial function and critical periods of brain development occur mainly in the prenatal and early neonatal stages, therapeutic approaches intended to improve oxidative phosphorylation should be provided in these periods.

Effects of caffeine on brain antioxidant status and mitochondrial respiration in acetaminophen-intoxicated mice

Hepatic encephalopathy is a pathophysiological complication of acute liver failure, which may be triggered by hepatotoxic drugs such as acetaminophen (APAP). Although APAP is safe in therapeutic concentration, APAP overdose may induce neurotoxicity, which is mainly associated with oxidative stress. Caffeine is a compound widely found in numerous natural beverages. However, the neuroprotective effect of caffeine remains unclear during APAP intoxication. The present study aimed to investigate the possible modulatory effects of caffeine on brain after APAP intoxication. Mice received intraperitoneal injections of APAP (250 mg/kg) and/or caffeine (20 mg/kg) and, 4 h after APAP administration, samples of brain and blood were collected for the biochemical analysis. APAP enhanced the transaminase activity levels in plasma, increased oxidative stress biomarkers (lipid peroxidation and reactive oxygen species), promoted an imbalance in endogenous antioxidant system in brain homogenate and increased the mortality. In contrast, APAP did not induce dysfunction of the mitochondrial bioenergetics. Co-treatment with caffeine modulated the biomarkers of oxidative stress as well as antioxidant system in brain. Besides, survival assays demonstrated that caffeine protective effects could be dose- and time-dependent. In addition, caffeine promoted an increase of mitochondrial bioenergetics response in brain by the enhancement of the oxidative phosphorylation, which could promote a better energy supply necessary for brain recovery. In conclusion, caffeine prevented APAP-induced biochemical alterations in brain and reduced lethality in APAP-intoxicated mice, these effects may relate to the preservation of the cellular antioxidant status, and these therapeutic properties could be useful in the treatment of hepatic encephalopathy induced by APAP intoxication.

An acylhydroquinone derivative produces OXPHOS uncoupling and sensitization to BH3 mimetic ABT-199 (Venetoclax) in human promyelocytic leukemia cells

Since cancer cells have different mitochondrial bioenergetic requirements than non-cancerous cells, therapeutic inhibition of its mitochondrial functionality continues to be an important target for anticancer drug discovery. In this study, a series of acylhydroquinones with different acyl-chain length, and their chlorinated derivatives, in the aromatic ring, synthesized by Fries rearrangement under microwave irradiation, were evaluated for their anticancer activity in two leukemia cell lines. Findings from the primary and secondary screening of the 18 acylhydroquinones, tested at 5 µM on acute promyelocytic leukemia HL-60 and acute lymphoblastic leukemia CEM cells lines, identified an acylchlorohydroquinone (12) with a highly selective anti-proliferative effect toward HL-60 cells. This compound induced S-phase arrest in the cell cycle progression of HL-60 cells with insignificant toxicity on leukemic CEM cells and non-cancerous Hs27 cells. In HL-60 leukemic cells, 12 triggered increased mitochondrial NADH oxidation, increased respiration in presence of oligomycin (state 4o), mitochondrial depolarization, and ROS production, suggesting an uncoupling of OXPHOS. This provoked a metabolic adaptation dependent on AMPK/ACC/autophagy axis, having the mitochondrial β-oxidation a pro-survival role since the combination of 12 and etomoxir, a carnitine palmitoyl-transferase (CPT) inhibitor promoted extensive HL-60 cell death. Finally, 12-induced metabolic stress sensitized to HL-60 cells to cell death by the FDA-approved anti-leukemic drug ABT-199, a BH3 mimetic. Therefore, our results suggest that acylchlorohydroquinone is a promising scaffold in anti-promyelocytic leukemia drug research.

The intake of an extract from seeds of Tamarindus indica L. modulates the endocrine function of adult male mice under a high fat diet

TBP is a natural product from Tamarindus indica L. seeds used as a natural remedy in India. This product is an antioxidant and may have beneficial effects on endocrine and metabolic functions. However, the regulatory mechanisms involved remain to be elucidated. In males, testosterone is synthesized by Leydig cells from the testis. With aging and obesity, testis function declines, leading to decreased testosterone synthesis. The aim of the current research is to determine how TBP improves testosterone production in male mice under a high fat diet leading to hypoandrogenic condition. Using C2C12 myoblast cells, we have found that TBP increased mitochondrial mass and oxygen respiration, as well as the production of the IGF-1 hormone. In addition, treatment of TM3 Leydig cells with TBP resulted in increased testosterone production. In mice under a high fat diet, TBP lowered blood glucose level and corticosterone production and improved total testosterone production after five weeks of treatment. In addition, testicular expressions of genes encoding the mitochondrial transporter of cholesterol (Star) and steroidogenic enzymes (Cyp11a1, Hsd3b1, Cyp17a1 and Hsd17b3) were increased by TBP. Hence, TBP may prevent the detrimental effects of long-term consumption of a high fat diet and may have health benefits on the endocrine function.

Low-dose caffeine administration increases fatty acid utilization and mitochondrial turnover in C2C12 skeletal myotubes

Caffeine has been shown to directly increase fatty acid oxidation, in part, by promoting mitochondrial biogenesis. Mitochondrial biogenesis is often coupled with mitophagy, the autophagy-lysosomal degradation of mitochondria. Increased mitochondrial biogenesis and mitophagy promote mitochondrial turnover, which can enhance aerobic metabolism. In addition, recent studies have revealed that cellular lipid droplets can be directly utilized in an autophagy-dependent manner, a process known as lipophagy. Although caffeine has been shown to promote autophagy and mitochondrial biogenesis in skeletal muscles, it remains unclear whether caffeine can increase lipophagy and mitochondrial turnover in skeletal muscle as well. The purpose of this study was to determine the possible contribution of lipophagy to caffeine-dependent lipid utilization. Furthermore, we sought to determine whether caffeine could increase mitochondrial turnover, which may also contribute to elevated fatty acid oxidation. Treating fully differentiated C2C12 skeletal myotubes with 0.5 mM oleic acid (OA) for 24 hr promoted an approximate 2.5-fold increase in cellular lipid storage. Treating skeletal myotubes with 0.5 mM OA plus 0.5 mM caffeine for an additional 24 hr effectively returned cellular lipid stores to control levels, and this was associated with an increase in markers of autophagosomes and autophagic flux, as well as elevated autophagosome density in TEM images. The addition of autophagy inhibitors 3-methyladenine (10 mM) or bafilomycin A1 (10 μM) reduced caffeine-dependent lipid utilization by approximately 30%. However, fluorescence and transmission electron microscopy analysis revealed no direct evidence of lipophagy in skeletal myotubes, and there was also no lipophagy-dependent increase in fatty acid oxidation. Finally, caffeine treatment promoted an 80% increase in mitochondrial turnover, which coincided with a 35% increase in mitochondrial fragmentation. Our results suggest that caffeine administration causes an autophagy-dependent decrease in lipid content by increasing mitochondrial turnover in mammalian skeletal myotubes.

Protective Effects of the Caffeine Against Neurodegenerative Diseases

Background:

Recent studies and increased interest of the scientific community helped to clarify the neurological health property of caffeine, one of the pharmacologically active substances most consumed in the world.

Methods:

This article is a review search to provide an overview on the current state of understanding neurobiochemical impact of caffeine, focusing on the ability of the drug to effectively counteract several neurodegenerative disorders such as Alzheimer’s, Parkinson’s, Huntington’s diseases, Multiple sclerosis and Amyotrophic lateral sclerosis.

Results:

Data collection shown in this review provide a significant therapeutic and prophylactic potentiality of caffeine which acts on human brain through several pathways because of its antioxidant activity combined with multiple molecular targets. However, the need to adjust the CF dosage to individuals, because some people are more sensitive to drugs than others, may constituted a limit to the CF effectiveness.

Conclusion:

What emerges from the complex of clinical and epidemiological studies is a significant CF potential impact against all neurological disorders. Although, further studies are needed to fully elucidate the several mechanisms of drug action which in part are still elusive.

Caffeine exposure induces browning features in adipose tissue in vitro and in vivo

Brown adipose tissue (BAT) is able to rapidly generate heat and metabolise macronutrients, such as glucose and lipids, through activation of mitochondrial uncoupling protein 1 (UCP1). Diet can modulate UCP1 function but the capacity of individual nutrients to promote the abundance and activity of UCP1 is not well established. Caffeine consumption has been associated with loss of body weight and increased energy expenditure, but whether it can activate UCP1 is unknown. This study examined the effect of caffeine on BAT thermogenesis in vitro and in vivo. Stem cell-derived adipocytes exposed to caffeine (1 mM) showed increased UCP1 protein abundance and cell metabolism with enhanced oxygen consumption and proton leak. These functional responses were associated with browning-like structural changes in mitochondrial and lipid droplet content. Caffeine also increased peroxisome proliferator-activated receptor gamma coactivator 1-alpha expression and mitochondrial biogenesis, together with a number of BAT selective and beige gene markers. In vivo, drinking coffee (but not water) stimulated the temperature of the supraclavicular region, which co-locates to the main region of BAT in adult humans, and is indicative of thermogenesis. Taken together, these results demonstrate that caffeine can promote BAT function at thermoneutrality and may have the potential to be used therapeutically in adult humans.

FR58P1a; a new uncoupler of OXPHOS that inhibits migration in triple-negative breast cancer cells via Sirt1/AMPK/β1-integrin pathway

Highly malignant triple-negative breast cancer (TNBC) cells rely mostly on glycolysis to maintain cellular homeostasis; however, mitochondria are still required for migration and metastasis. Taking advantage of the metabolic flexibility of TNBC MDA-MB-231 cells to generate subpopulations with glycolytic or oxidative phenotypes, we screened phenolic compounds containing an ortho-carbonyl group with mitochondrial activity and identified a bromoalkyl-ester of hydroquinone named FR58P1a, as a mitochondrial metabolism-affecting compound that uncouples OXPHOS through a protonophoric mechanism. In contrast to well-known protonophore uncoupler FCCP, FR58P1a does not depolarize the plasma membrane and its effect on the mitochondrial membrane potential and bioenergetics is moderate suggesting a mild uncoupling of OXPHOS. FR58P1a activates AMPK in a Sirt1-dependent fashion. Although the activation of Sirt1/AMPK axis by FR58P1a has a cyto-protective role, selectively inhibits fibronectin-dependent adhesion and migration in TNBC cells but not in non-tumoral MCF10A cells by decreasing β1-integrin at the cell surface. Prolonged exposure to FR58P1a triggers a metabolic reprograming in TNBC cells characterized by down-regulation of OXPHOS-related genes that promote cell survival but comprise their ability to migrate. Taken together, our results show that TNBC cell migration is susceptible to mitochondrial alterations induced by small molecules as FR58P1a, which may have therapeutic implications.

Guarana (Paullinia cupana) Stimulates Mitochondrial Biogenesis in Mice Fed High-Fat Diet

The aim of this study was to evaluate the effects of guarana on mitochondrial biogenesis in a high-fat diet (HFD)-fed mice. C57BL6J mice were divided in two groups: high-fat diet HFD and high-fat diet + guarana (HFD-GUA). Both groups received HFD and water ad libitum and the HFD-GUA group also received a daily gavage of guarana (1 g/kg weight). Body weight and food intake was measured weekly. Glycemic, triglyceride, and cholesterol levels were determined. VO₂ and energy expenditure (EE) were determined by indirect calorimetry. Gene expression was evaluated by real-time PCR and protein content by western blotting. The HFD-GUA group presented lower body weight, subcutaneous, retroperitoneal, visceral, and epididyimal adipose tissue depots, and glycemic and triglyceride levels, with no change in food intake and cholesterol levels. Furthermore, the HFD-GUA group presented an increase in VO₂ and basal energy expenditure (EE), as well as Pgc1α, Creb1, Ampka1, Nrf1, Nrf2, and Sirt1 expression in the muscle and brown adipose tissue. In addition, the HFD-GUA group presented an increase in mtDNA (mitochondrial deoxyribonucleic acid) content in the muscle when compared to the HFD group. Thus, our data showed that guarana leads to an increase in energetic metabolism and stimulates mitochondrial biogenesis, contributing to control of weight gain, even when associated with high-fat diet.

Metabolic effects of physiological levels of caffeine in myotubes

Caffeine has been shown to stimulate multiple major regulators of cell energetics including AMP-activated protein kinase (AMPK) and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII). Additionally, caffeine induces peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and mitochondrial biogenesis. While caffeine enhances oxidative metabolism, experimental concentrations often exceed physiologically attainable concentrations through diet. This work measured the effects of low-level caffeine on cellular metabolism and gene expression in myotubes, as well as the dependence of caffeine's effects on the nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPARβ/δ). C2C12 myotubes were treated with various doses of caffeine for up to 24 h. Gene and protein expression were measured via qRT-PCR and Western blot, respectively. Cellular metabolism was determined via oxygen consumption and extracellular acidification rate. Caffeine significantly induced regulators of mitochondrial biogenesis and oxidative metabolism. Mitochondrial staining was suppressed in PPARβ/δ-inhibited cells which was rescued by concurrent caffeine treatment. Caffeine-treated cells also displayed elevated peak oxidative metabolism which was partially abolished following PPARβ/δ inhibition. Similar to past observations, glucose uptake and GLUT4 content were elevated in caffeine-treated cells, however, glycolytic metabolism was unaltered following caffeine treatment. Physiological levels of caffeine appear to enhance cell metabolism through mechanisms partially dependent on PPARβ/δ.

Virtual Cell Based Assay simulations of intra-mitochondrial concentrations in hepatocytes and cardiomyocytes

In order to replace the use of animals in toxicity testing, there is a need to predict human in vivo toxic doses from concentrations that cause adverse effects in in vitro test systems. The virtual cell based assay (VCBA) has been developed to simulate intracellular concentrations as a function of time, and can be used to interpret in vitro concentration-response curves. In this study we refine and extend the VCBA model by including additional target-organ cell models and by simulating the fate and effects of chemicals at the organelle level. In particular, we describe the extension of the original VCBA to simulate chemical fate in liver (HepaRG) cells and cardiomyocytes (ICell cardiomyocytes), and we explore the effects of chemicals at the mitochondrial level. This includes a comparison of: a) in vitro results on cell viability and mitochondrial membrane potential (mmp) from two cell models (HepaRG cells and ICell cardiomyocytes); and b) VCBA simulations, including the cell and mitochondrial compartment, simulating the mmp for both cell types. This proof of concept study illustrates how the relationship between intra cellular, intra mitochondrial concentration, mmp and cell toxicity can be obtained by using the VCBA.

Effect of novel dietary supplement on metabolism in vitro and in vivo

Obesity is an increasingly prevalent and preventable morbidity with multiple behavioral, surgical and pharmacological interventions currently available. Commercial dietary supplements are often advertised to stimulate metabolism and cause rapid weight and/or fat loss, although few well-controlled studies have demonstrated such effects. We describe a commercially available dietary supplement (purportedly containing caffeine, catechins, and other metabolic stimulators) on resting metabolic rate in humans, and on metabolism, mitochondrial content, and related gene expression in vitro. Human males ingested either a placebo or commercially available supplement (RF) in a randomized double-blind placebo-controlled cross-over fashion. Metabolic rate, respiratory exchange ratio, and blood pressure were measured hourly for 3 h post-ingestion. To investigate molecular effects, human rhabdomyosarcoma cells (RD) and mouse myocytes (C2C12) were treated with various doses of RF for various durations. RF enhanced energy expenditure and systolic blood pressure in human males without altering substrate utilization. In myocytes, RF enhanced metabolism, metabolic gene expression, and mitochondrial content suggesting RF may target common energetic pathways which control mitochondrial biogenesis. RF appears to increase metabolism immediately following ingestion, although it is unclear if RF provides benefits beyond those provided by caffeine alone. Additional research is needed to examine safety and efficacy for human weight loss.

Effects of controlled doses of Oxyelite Pro on physical performance in rats

BACKGROUND

OxyElite Pro (OEP) is a dietary supplement to increase metabolism which contains as key stimulant the ingredient 1,3-dimethylamylamine (DMAA). Serious adverse effects have been reported after OEP consumption however, these effects are related to poisoning or overdose. To our knowledge, no one studied the effects of OEP at controlled doses. Thus, the aim of this study was to evaluate acute and chronic OEP affects, at controlled doses in Wistar rats, on physical performance, metabolic parameters, liver injury markers and oxidative stress markers and mitochondrial biogenesis in skeletal muscle.

METHODS

Rats were divided in control, 4.3 mg OEP/kg, 12.9 mg OEP/kg and 25.8 mg OEP/kg. All groups were submitted to supplementation with OEP for 4 weeks and the experimental protocols were performed 30 min after the first OEP administration (acute response) and 30 min after the last OEP administration at the end of the forth week (chronic response).

RESULTS

Running distance and running time increased after acute administration of 12.9 mg OEP/kg (2.6-fold) and 25.8 mg OEP/kg (2.8-fold). Since no effect on the exercise tolerance test was observed at the lower OEP dose (4.3 mg OEP/kg), this group was removed from further analyzes. On other hand, running distance and running time decreased after daily supplementation for 4 weeks also in both groups (64% in 12.9 mg OEP/kg and 72% in 25.8 mg OEP/kg). Chronic supplementation at both 12.9 and 25.8 mg OEP/kg decreased TBARS levels in soleus muscle (36 and 31%) and liver (43 and 25%). AOPP was also decreased by both doses in the liver (39 and 45%). Chronic administration of the highest dose, 25.8 mg OEP/kg, was able to reduce mRNA expression of PGC-1α in soleus muscle (25%). No effect was found in other analyses such as spontaneous physical activity, body weight, food and water intake, hepatic toxicity, cardiac oxidative stress and mitochondrial DNA amount.

CONCLUSION

Maximum and not recommended doses of OEP ingested acutely presented stimulating effect on the ability to exercise. However, its daily consumption for 4 weeks showed antioxidant effects in soleus muscle and liver which may have decreased the PGC-1α mRNA expression on soleus muscle and contributed to the impaired performance in the exercise tolerance test.

Leucine treatment enhances oxidative capacity through complete carbohydrate oxidation and increased mitochondrial density in skeletal muscle cells

Leucine has been largely implicated for increasing muscle protein synthesis in addition to stimulating mitochondrial biosynthesis. Limited evidence is currently available on the effects and potential benefits of leucine treatment on skeletal muscle cell glycolytic and oxidative metabolism. This work identified the effects of leucine treatment on oxidative and glycolytic metabolism as well as metabolic rate of human and murine skeletal muscle cells. Human rhabdomyosarcoma cells (RD) and mouse myoblast cells (C2C12) were treated with leucine at either 100 or 500 μM for 24 or 48 h. Glycolytic metabolism was quantified by measuring extracellular acidification rate (ECAR) and oxidative metabolism was quantified by measuring oxygen consumption rate. Peroxisome proliferator-activated receptor coactivator 1 alpha (PGC-1α), an important stimulator of mitochondrial biosynthesis, was quantified using flow cytometry and verified by immunofluorescent confocal microscopy. Mitochondrial content was quantified using mitochondrial and cytochrome C staining measured by flow cytometry and confirmed with confocal microscopy. Treatment with leucine significantly increased both basal and peak oxidative metabolism in both cell models. Leucine treated cells also exhibited significantly greater mitochondrial proton leak, which is associated with heightened energy expenditure. Basal ECAR was significantly reduced in both cell models following leucine treatment, evidence of reduced lactate export and more complete carbohydrate oxidation. In addition, both PGC-1α and cytochrome C expression were significantly elevated in addition to mitochondrial content following 48 h of leucine treatment. Our observations demonstrated few dose-dependent responses induced by leucine; however, leucine treatment did induce a significant dose-dependent expression of PGC-1α in both cell models. Interestingly, C2C12 cells treated with leucine exhibited dose-dependently reduced ATP content, while RD ATP content remain unchanged. Leucine presents a potent dietary constituent with low lethality with numerous beneficial effects for increasing oxidative preference and capacity in skeletal muscle. Our observations demonstrate that leucine can enhance oxidative capacity and carbohydrate oxidation efficiency, as well as verify previous observations of increased mitochondrial content.

Ubiquinol rescues simvastatin-suppression of mitochondrial content, function and metabolism: implications for statin-induced rhabdomyolysis

Statin medications diminish cholesterol biosynthesis and are commonly prescribed to reduce cardiovascular disease. Statins also reduce production of ubiquinol, a vital component of mitochondrial energy production; ubiquinol reduction may contribute to rhabdomyolysis. Human rhabdomyosarcoma cells were treated with either ethanol and dimethyl sulfoxide (DMSO) control, or simvastatin at 5 µM or 10 µM, or simvastatin at 5 µM with ubiquinol at 0.5 µM or 1.0 µM for 24 h or 48 h. PGC-1α RNA levels were determined using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Mitochondrial content was determined using flow cytometry and immunocytochemistry. Metabolism was determined by quantification of extracellular acidification rate and oxygen consumption rate. Treatment of human rhabdomyosarcoma cells with simvastatin significantly reduced oxidative, total metabolism, and cellular ATP content in a time- and dose-dependent manner which was rescued by concurrent treatment with ubiquinol. Treatment with simvastatin significantly reduced mitochondrial content as well as cell viability which were both rescued by simultaneous treatment with ubiquinol. This work demonstrates that the addition of ubiquinol to current statin treatment regimens may protect muscle cells from myopathies.

Treatment of human muscle cells with popular dietary supplements increase mitochondrial function and metabolic rate

Background

Obesity is a common pathology with increasing incidence, and is associated with increased mortality and healthcare costs. Several treatment options for obesity are currently available ranging from behavioral modifications to pharmaceutical agents. Many popular dietary supplements claim to enhance weight loss by acting as metabolic stimulators, however direct tests of their effect on metabolism have not been performed.

Purpose

This work identified the effects popular dietary supplements on metabolic rate and mitochondrial biosynthesis in human skeletal muscle cells.

Methods

Human rhabdomyosarcoma cells were treated with popular dietary supplements at varied doses for 24 hours. Peroxisome proliferator-activated receptor coactivator 1 alpha (PGC-1α), an important stimulator of mitochondrial biosynthesis, was quantified using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Mitochondrial content was measured using flow cytometry confirmed with confocal microscopy. Glycolytic metabolism was quantified by measuring extracellular acidification rate (ECAR) and oxidative metabolism was quantified by measuring oxygen consumption rate (OCR). Total relative metabolism was quantified using WST-1 end point assay.

Results

Treatment of human rhabdomyosarcoma cells with dietary supplements OxyElite Pro (OEP) or Cellucore HD (CHD) induced PGC-1α leading to significantly increased mitochondrial content. Glycolytic and oxidative capacities were also significantly increased following treatment with OEP or CHD.

Conclusion

This is the first work to identify metabolic adaptations in muscle cells following treatment with popular dietary supplements including enhanced mitochondrial biosynthesis, and glycolytic, oxidative and total metabolism.