Age-related muscle wasting and dysfunction render the elderly population vulnerable and incapacitated, while underlying mechanisms are poorly understood. Here, we implicate the CERS1 enzyme of the de novo sphingolipid synthesis pathway in the pathogenesis of age-related skeletal muscle impairment. In humans, CERS1 abundance declines with aging in skeletal muscle cells and, correlates with biological pathways involved in muscle function and myogenesis. Furthermore, CERS1 is upregulated during myogenic differentiation. Pharmacological or genetic inhibition of CERS1 in aged mice blunts myogenesis and deteriorates aged skeletal muscle mass and function, which is associated with the occurrence of morphological features typical of inflammation and fibrosis. Ablation of the CERS1 orthologue lagr-1 in Caenorhabditis elegans similarly exacerbates the age-associated decline in muscle function and integrity. We discover genetic variants reducing CERS1 expression in human skeletal muscle and Mendelian randomization analysis in the UK biobank cohort shows that these variants reduce muscle grip strength and overall health. In summary, our findings link age-related impairments in muscle function to a reduction in CERS1, thereby underlining the importance of the sphingolipid biosynthesis pathway in age-related muscle homeostasis.

Objective: The mitochondrial unfolded protein response (UPRmt) is an adaptive cellular response to stress to ensure mitochondrial proteostasis and function. Here we explore the capacity of physical exercise to induce UPRmt in the skeletal muscle. Methods: Therefore, we combined mouse models of exercise (swimming and treadmill running), pharmacological intervention, and bioinformatics analyses. Results: Firstly, RNA sequencing and Western blotting analysis revealed that an acute aerobic session stimulated several mitostress-related genes and protein content in muscle, including the UPRmt markers. Conversely, using a large panel of isogenic strains of BXD mice, we identified that BXD73a and 73b strains displayed low levels of several UPRmt-related genes in the skeletal muscle, and this genotypic feature was accompanied by body weight gain, lower locomotor activity, and aerobic capacity. Finally, we identified that c-Jun N-terminal kinase (JNK) activation was critical in exercise-induced UPRmt in the skeletal muscle since pharmacological JNK pathway inhibition blunted exercise-induced UPRmt markers in mice muscle. Conclusion: Our findings provide new insights into how exercise triggers mitostress signals toward the oxidative capacity in the skeletal muscle.

Dysfunction of the adipose tissue metabolism is considered as a significant hallmark of aging. It has been proposed that α-β hydrolase domain containing 5 (ABHD5) plays a critical role in the control of lipolysis. However, the role of ABHD5 in the control of lipolysis during aging or exercise is unknown. Here we combined the experimental mouse model with transcriptomic analyzes by using murine and human databases to explore the role of ABHD5 in the adipose tissue during aging and in response to exercise. Transcriptomic data revealed a downregulation of Abhd5 messenger RNA levels in the subcutaneous white adipose tissue (scWAT) over time in individuals from 20 to 69 years old. Aged mice displayed dramatic reduction of ABHD5 protein content and lipolytic-related proteins in the scWAT. Interestingly, 4 weeks of high-intensity interval training increased ABHD5 protein level and restored the lipolytic pathway in the scWAT of aged mice. Altogether, our findings demonstrated that aging affects ABHD5 content in the adipose tissue of mice and humans. Conversely, exercise increases ABHD5 activity, recovering the lipolytic activity in aged mice.

Intriguingly, hyperinsulinemia, and hyperglycemia can predispose insulin resistance, obesity, and type 2 diabetes, leading to metabolic disturbances. Conversely, physical exercise stimulates skeletal muscle glucose uptake, improving whole-body glucose homeostasis. Therefore, we investigated the impact of short-term physical activity in a mouse model (Slc2a4+/−) that spontaneously develops hyperinsulinemia and hyperglycemia even when fed on a chow diet. Slc2a4+/− mice were used, that performed 5 days of endurance or strength exercise training. Further analysis included physiological tests (GTT and ITT), skeletal muscle glucose uptake, skeletal muscle RNA-sequencing, mitochondrial function, and experiments with C2C12 cell line. When Slc2a4+/− mice were submitted to the endurance or strength training protocol, improvements were observed in the skeletal muscle glucose uptake and glucose metabolism, associated with broad transcriptomic modulation, that was, in part, related to mitochondrial adaptations. The endurance training, but not the strength protocol, was effective in improving skeletal muscle mitochondrial activity and unfolded protein response markers (UPRmt). Moreover, experiments with C2C12 cells indicated that insulin or glucose levels could contribute to these mitochondrial adaptations in skeletal muscle. Both short-term exercise protocols were efficient in whole-body glucose homeostasis and insulin resistance. While endurance exercise plays an important role in transcriptome and mitochondrial activity, strength exercise mostly affects post-translational mechanisms and protein synthesis in skeletal muscle. Thus, the performance of both types of physical exercise proved to be a very effective way to mitigate the impacts of hyperglycemia and hyperinsulinemia in the Slc2a4+/− mouse model.

Disruption of mitochondrial function and protein homeostasis plays a central role in aging. However, how these processes interact and what governs their failure in aging remain poorly understood. Here, we showed that cer- amide biosynthesis controls the decline in mitochondrial and protein homeostasis during muscle aging. Anal- ysis of transcriptome datasets derived from muscle biopsies obtained from both aged individuals and patients with a diverse range of muscle disorders revealed that changes in ceramide biosynthesis, as well as disturbances in mitochondrial and protein homeostasis pathways, are prevalent features in these conditions. By performing targeted lipidomics analyses, we found that ceramides accumulated in skeletal muscle with increasing age across Caenorhabditis elegans, mice, and humans. Inhibition of serine palmitoyltransferase (SPT), the rate -lim- iting enzyme of the ceramide de novo synthesis, by gene silencing or by treatment with myriocin restored pro- teostasis and mitochondrial function in human myoblasts, in C. elegans, and in the skeletal muscles of mice during aging. Restoration of these age-related processes improved health and life span in the nematode and muscle health and fitness in mice. Collectively, our data implicate pharmacological and genetic suppression of ceramide biosynthesis as potential therapeutic approaches to delay muscle aging and to manage related pro- teinopathies via mitochondrial and proteostasis remodeling.

Hypothalamic interleukin-6 (IL6) exerts a broad metabolic control. Here, we demonstrated that IL6 activates the ERK1/2 pathway in the ventromedial hypothalamus (VMH), stimulating AMPK/ACC signaling and fatty acid oxidation in mouse skeletal muscle. Bioinformatics analysis revealed that the hypothalamic IL6/ERK1/2 axis is closely associated with fatty acid oxidation– and mitochondrial-related genes in the skeletal muscle of isogenic BXD mouse strains and humans. We showed that the hypothalamic IL6/ERK1/2 pathway requires the α2-adrenergic pathway to modify fatty acid skeletal muscle metabolism. To address the physiological relevance of these findings, we demonstrated that this neuromuscular circuit is required to underpin AMPK/ACC signaling activation and fatty acid oxidation after exercise. Last, the selective down-regulation of IL6 receptor in VMH abolished the effects of exercise to sustain AMPK and ACC phosphorylation and fatty acid oxidation in the muscle after exercise. Together, these data demonstrated that the IL6/ERK axis in VMH controls fatty acid metabolism in the skeletal muscle.

Duchenne muscular dystrophy (DMD), the most common muscular dystrophy, is a severe muscle disorder, causing muscle weakness, loss of independence, and premature death. Here, we establish the link between sphingolipids and muscular dystrophy. Transcripts of sphingolipid de novo biosynthesis pathway are up-regulated in skeletal muscle of patients with DMD and other muscular dystrophies, which is accompanied by accumulation of metabolites of the sphingolipid pathway in muscle and plasma. Pharmacological inhibition of sphingolipid synthesis by myriocin in the mdx mouse model of DMD ameliorated the loss in muscle function while reducing inflammation, improving Ca 2+ homeostasis, preventing fibrosis of the skeletal muscle, heart, and diaphragm, and restoring the balance between M1 and M2 macrophages. Myriocin alleviated the DMD phenotype more than glucocorticoids. Our study identifies inhibition of sphingolipid synthesis, targeting multiple pathogenetic pathways simultaneously, as a strong candidate for treatment of muscular dystrophies.

Aging is associated with changes in glucose homeostasis related to both decreased insulin secretion and/or impaired insulin action, contributing to the high prevalence of type 2 diabetes (T2D) in the elderly population. Additionally, studies are showing that chronically high levels of circulating insulin can also lead to insulin resistance. In contrast, physical exercise has been a strategy used to improve insulin sensitivity and metabolic health. However, the molecular alterations resulting from the effects of physical exercise in the liver on age-related hyperinsulinemia conditions are not yet fully established. This study aimed to investigate the effects of 7 days of aerobic exercise on hepatic metabolism in aged hyperinsulinemic rats (i.e., Wistar and F344) and in Slc2a4+/− mice (hyperglycemic and hyperinsulinemic mice). Both aged models showed alterations in insulin and glucose tolerance, which were associated with essential changes in hepatic fat metabolism (lipogenesis, gluconeogenesis, and inflammation). In contrast, 7 days of physical exercise was efficient in improving whole-body glucose and insulin sensitivity, and hepatic metabolism. The Slc2a4+/− mice presented significant metabolic impairments (insulin resistance and hepatic fat accumulation) that were improved by short-term exercise training. In this scenario, high circulating insulin may be an important contributor to age-related insulin resistance and hepatic disarrangements in some specific conditions. In conclusion, our data demonstrated that short-term aerobic exercise was able to control mechanisms related to hepatic fat accumulation and insulin sensitivity in aged rodents. These effects could contribute to late-life metabolic health and prevent the development/progression of age-related T2D.

Age-related muscle dysfunction and sarcopenia are major causes of physical incapacitation in older adults and currently lack viable treatment strategies. Here we find that sphingolipids accumulate in mouse skeletal muscle upon aging and that both genetic and pharmacological inhibition of sphingolipid synthesis prevent age-related decline in muscle mass while enhancing strength and exercise capacity. Inhibition of sphingolipid synthesis confers increased myogenic potential and promotes protein synthesis. Within the sphingolipid pathway, we show that accumulation of dihydroceramides is the culprit disturbing myofibrillar homeostasis. The relevance of sphingolipid pathways in human aging is demonstrated in two cohorts, the UK Biobank and Helsinki Birth Cohort Study in which gene expression-reducing variants of SPTLC1 and DEGS1 are associated with improved and reduced fitness of older individuals, respectively. These findings identify sphingolipid synthesis inhibition as an attractive therapeutic strategy for age-related sarcopenia and co-occurring pathologies.

The maintenance of mitochondrial activity in hypothalamic neurons is determinant to the control of energy homeostasis in mammals. Disturbs in the mitochondrial proteostasis can trigger the mitonuclear imbalance and mitochondrial unfolded protein response (UPRmt) to guarantee the mitochondrial integrity and function. However, the role of mitonuclear imbalance and UPRmt in hypothalamic cells are unclear. Combining the transcriptomic analyses from BXD mice database and in vivo experiments, we demonstrated that physical training alters the mitochondrial proteostasis in the hypothalamus of C57BL/6J mice. This physical training elicited the mitonuclear protein imbalance, increasing the mtCO-1/Atp5a ratio, which was accompanied by high levels of UPRmt markers in the hypothalamus. Also, physical training increased the maximum mitochondrial respiratory capacity in the brain. Interestingly, the transcriptomic analysis across several strains of the isogenic BXD mice revealed that hypothalamic mitochondrial DNA-encoded genes were negatively correlated with body weight and several genes related to the orexigenic response. As expected, physical training reduced body weight and food intake. Interestingly, we found an abundance of mt-CO1, a mitochondrial DNA-encoded protein, in NPY-producing neurons in the lateral hypothalamus nucleus of exercised mice. Collectively, our data demonstrated that physical training altered the mitochondrial proteostasis and induced the mitonuclear protein imbalance and UPRmt in hypothalamic cells.

Notch1 protein has an important role in the hepatic metabolism. In this way, it has been observed in obese individuals that Notch1 is correlated with insulin resistance in the liver, which makes it an interesting research target. On the other hand, the physical exercise are associated with the prevention and treatment of insulin resistance and type 2 diabetes. Thus, the present study aims to verify the role of physical exercise in the Notch1 protein modulation in the hepatic tissue of obese mice and its contribution in the control of gluconeogenesis. For this, we used obese mice induced by high fat diet and ob/ob animals. The trained animals group performed treadmill-running protocol, with intensity corresponding to 70% of the maximum running speed, for a period of four weeks. At the end of the exercise protocol (24 hours later), we analyzed the physiological parameters, mRNA levels, and protein content of key molecules in the control of gluconeogenesis and Notch1 signaling. We found that exercise reversed the physiological damage generated by obesity. In addition, trained animals showed a reduction in protein content and Notch1 activity when compared to the sedentary obese group. Furthermore, we observed reduction in pyruvate intolerance in exercised animals and a decrease in gluconeogenesis enzymes. Such findings were also observed in ob/ob mice submitted to physical exercise. Thus, we verified the physical exercise mice reduce Nocth1 activation and decrease PEPCK protein content. Finally, we found that inhibition of Notch1 activity decreases pyruvate intolerance as well as reduces the protein content of gluconeogenesis enzymes. Therefore, we concluded that physical exercise is able to modulate the Notch1 pathway in the liver and contribute to the gluconeogenesis control in obese mice. Disclosure R.C. Gaspar: None. V. Muñoz: None. S.C. Nakandakari: None. B.M. Crisol: None. R.F.L. Vieira: None. L.R. Conceição: None. A. Silva: None. D.E. Cintra: None. L.P. Moura: None. E.R. Ropelle: None. J.R. Pauli: None. Funding São Paulo Research Foundation (2019/11338-9, 2017/20542-3)

The impairment of the mitochondrial functions is a hallmark of aging. During aging, there is a downregulation of two mechanisms strictly associated with mitochondrial integrity, including the mitonuclear imbalance (eg, imbalance in mitochondrial- versus nuclear-encoded mitochondrial proteins) and the mitochondrial unfolded protein response (UPRmt). Here, we evaluated the effects of aerobic exercise in the mitonuclear imbalance and UPRmt markers in the skeletal muscle of old mice. We combined the physiological tests, molecular and bioinformatic analyzes to evaluate the effects of 4 weeks of aerobic exercise training on mitonuclear imbalance and UPRmt markers in the skeletal muscle of young (2 months) and aged (24 months) C57BL/6J mice. Initially, we found that aging reduced several mitochondrial genes in the gastrocnemius muscle, and it was accompanied by the low levels of UPRmt markers, including Yme1l1 and Clpp mRNA. As expected, physical training improved the whole-body metabolism and physical performance of aged mice. The aerobic exercise increased key proteins involved in the mitochondrial biogenesis/functions (VDAC and SIRT1) along with mitochondrial-encoded genes (mtNd1, mtCytB, and mtD-Loop) in the skeletal muscle of old mice. Interestingly, aerobic exercise induced the mitonuclear imbalance, increasing MTCO1/ATP5a ratio and UPRmt markers in the skeletal muscle, including HSP60, Lonp1, and Yme1L1 protein levels in the gastrocnemius muscle of aged mice. These data demonstrate that aerobic exercise training induced mitonuclear imbalance and UPRmt in the skeletal muscle during aging. These phenomena could be involved in the improvement of the mitochondrial metabolism and oxidative capacity in aged individuals.

The impairment of mitochondrial metabolism is a hallmark of aging. Mitonuclear imbalance and the mitochondrial unfolded protein response (UPRmt) are two conserved mitochondrial mechanisms that play critical roles in ensuring mitochondrial proteostasis and function. Here, we combined bioinformatics, physiological, and molecular analyses to examine the role of mitonuclear imbalance and UPRmt in the skeletal muscle of aged rodents and humans. The analysis of transcripts from the skeletal muscle of aged humans (60–70 years old) revealed that individuals with higher levels of UPRmt-related genes displayed a consistent increase in several mitochondrial-related genes, including the OXPHOS-associated genes. Interestingly, high-intensity interval training (HIIT) was effective in stimulating the mitonuclear imbalance and UPRmt in the skeletal muscle of aged mice. Furthermore, these results were accompanied by higher levels of several mitochondrial markers and improvements in physiological parameters and physical performance. These data indicate that the maintenance or stimulation of the mitonuclear imbalance and UPRmt in the skeletal muscle could ensure mitochondrial proteostasis during aging, revealing new insights into targeting mitochondrial metabolism by using physical exercise.

TRB3, a mammalian homolog of Drosophila tribbles, plays an important role in multiple tissues and it has been implicated in stress response regulation and metabolic control. However, the role of hepatic TRB3 and its relationship with endoplasmic reticulum stress (ER stress) during aging has not been elucidated. Thus, the present study aimed to explore the association of aging with TRB3 and ER stress on the hepatic glucose production in Wistar rats. We found the TRB3 protein content to be higher in livers of old rats (27 months) compared to young (3 months) and middle-aged (17 months) rats. The increased content of hepatic TRB3 of the old rats was associated with insulin resistance (decreased protein kinase B (Akt) and Forkhead Box O1 (FoxO1) phosphorylation) and increased enzymes of gluconeogenesis (phosphoenolpyruvate carboxykinase (PEPCK) and Glucose 6-phosphatase (G6Pase)). Moreover, aging was associated with activation of the endoplasmic reticulum stress pathway-related molecules, with an increase in phosphorylation of Inositol-requiring enzyme 1 (p-IRE1α), the protein kinase RNA-like endoplasmic reticulum kinase (p-PERK), eukaryotic translation initiation factor-α (p-eIF2α), binding immunoglobulin protein (BiP), and the C/EBP homologous protein (CHOP) contents in rats. These molecular changes resulted in increased liver glucose production in response to the pyruvate challenge and hyperglycemia of the old rats. In conclusion, our results suggested that, by interfering with insulin signaling in the liver, TRB3 was associated with ER stress and increased hepatic glucose production in aging rats.

A lipolise e um mecanismo biologico complexo responsavel por promover a degradacao de moleculas de gordura para obtencao de substrato energetico. O processo de envelhecimento e acompanhado pelo aumento do acumulo de tecido adiposo, que ocorre ao menos em parte, devido a reducao da capacidade de ativacao da lipolise. Por outro lado, sabidamente o exercicio fisico e reconhecido como um potente estimulador do processo da lipolise. Recentemente, a proteina ABHD5 (do ingles, α-β hidrolase domain-contain protein 5) foi descrita como molecula chave no controle da lipolise, ao passo que a interacao entre a ABHD5/ATGL e determinante para a metabolizacao de triglicerideos para obtencao de energia. Contudo pouco se conhece sobre a influencia do envelhecimento e do exercicio fisico sobre a expressao/atividade da ABHD5. Portanto o atual projeto pretende avaliar o efeito do envelhecimento sobre o conteudo proteico de ABHD5 no tecido adiposo de camundongos, bem como investigar o papel do exercicio fisico sobre a ABHD5 e a ativacao da lipolise em camundongos idosos. A realizacao do presente projeto podera ajudar a elucidar o papel da ABHD5 sobre o acumulo de gordura durante o envelhecimento, bem como determinar a possivel capacidade do exercicio fisico em modular a atividade da ABHD5 e da lipolise no envelhecimento.

Adiponectin is an adipokine that acts in the control of energy homeostasis. The adaptor protein containing the pleckstrin homology domain, phosphotyrosine‐binding domain, and leucine zipper motif 1 (APPL1) is a key protein in the adiponectin signaling. The APPL1 mediates a positive effect on the insulin signaling through the interaction with the phosphoinositide 3‐kinase (PI3K). Thus, the present study aimed to explore the effects of an acute physical exercise session on the hypothalamic adiponectin signaling. Firstly, using bioinformatics analysis, we found a negative correlation between hypothalamic APPL1 mRNA levels and food consumption in several strains of genetically diverse BXD mice. Also, the mice and the human database revealed a positive correlation between the levels of APPL1 mRNA and PI3K mRNA. At the molecular level, the exercised mice showed increased APPL1 and PI3K (p110) protein contents in the hypothalamus of Swiss mice. Furthermore, the exercise increases co‐localization between APPL1 and PI3K p110 predominantly in neurons of the arcuate nucleus of hypothalamus (ARC). Finally, we found an acute exercise session reduced the food intake 5 hr after the end of fasting. In conclusion, our results indicate that physical exercise reduces the food intake and increases some proteins related to adiponectin pathway in the hypothalamus of lean mice.

Purpose Nicotinamide riboside (NR) acts as a potent NAD + precursor and improves mitochondrial oxidative capacity and mitochondrial biogenesis in several organisms. However, the effects of NR supplementation on aerobic performance remain unclear. Here, we evaluated the effects of NR supplementation on the muscle metabolism and aerobic capacity of sedentary and trained mice. Methods Male C57BL/6 J mice were supplemented with NR (400 mg/Kg/day) over 5 and 10 weeks. The training protocol consisted of 5 weeks of treadmill aerobic exercise, for 60 min a day, 5 days a week. Bioinformatic and physiological assays were combined with biochemical and molecular assays to evaluate the experimental groups. Results NR supplementation by itself did not change the aerobic performance, even though 5 weeks of NR supplementation increased NAD + levels in the skeletal muscle. However, combining NR supplementation and aerobic training increased the aerobic performance compared to the trained group. This was accompanied by an increased protein content of NMNAT3, the rate-limiting enzyme for NAD + biosynthesis and mitochondrial proteins, including MTCO1 and ATP5a. Interestingly, the transcriptomic analysis using a large panel of isogenic strains of BXD mice confirmed that the Nmnat3 gene in the skeletal muscle is correlated with several mitochondrial markers and with different phenotypes related to physical exercise. Finally, NR supplementation during aerobic training markedly increased the amount of type I fibers in the skeletal muscle. Conclusion Taken together, our results indicate that NR may be an interesting strategy to improve mitochondrial metabolism and aerobic capacity.

A atividade mitocondrial em neurônios hipotalâmicos é determinante para o controle da homeostase energética em mamíferos. Sabe-se que a abundância dos níveis de NAD+ induz potentes sinais para as mitocôndrias, como a indução do "desequilíbrio mito-nuclear" e a ativação da UPRmt, do inglês unfolded protein response, aumentando a capacidade oxidativa e a biogênese mitocondrial. Objetivo: Avaliar se o exercício físico ou se a suplementação com Ribosídeo de Nicotinamida, precursores de NAD+, podem desencadear estes processos no hipotálamo de camundongos. Metodologia: Exercício em esteira ergométrica; suplementação via oral; análises por western blot e programa estatístico (GraphPad Prism 5). Resultados: Não houve indução do desequilíbrio mito-nuclear e da UPRmt, embora o exercício físico tenha aumentado o conteúdo proteico de uma proteína mitocondrial, MTCO1.

A obesidade pode ser responsável pela perda da acuidade visual. Recentemente uma proteína conhecida como Clusterina tem sido descrita como protetora de superfície ocular. No entanto, ainda não está claro se o exercício físico é capaz de modular os níveis de clusterina na retina. Buscamos investigar o papel do exercício combinado no metabolismo da clusterina na retina de camundongos obesos. Camundongos Swiss foram distribuídos em grupos controle (CT), obesos sedentários (OBS) e obesos treinados (OBC). Os animais foram submetidos a um protocolo de exercícios combinados de curta duração que consistiu em treinamento de força em escada seguido de exercício aeróbio em esteira por 7 dias, totalizando 1h / dia. Posteriormente, a retina foi excisada e analisada por Western Blot e RT-PCR. O grupo OBC melhorou a sinalização de insulina em comparação com CTS e OBS. Além disso, o grupo OBC apresentou um aumento no conteúdo de IL-10 e redução do perfil pró-inflamatório. Os níveis de clusterina reduziram-se, em média, 18% nos grupos OBC vs OBS. Em suma, o treinamento combinado mostrou-se eficiente na redução do perfil inflamatório através da diminuição do conteúdo das proteínas envolvidas e por consequência melhora na ação da insulina. Além disso, o exercício foi capaz de reduzir os níveis de clusterina tecidual. Esta similaridade no comportamento, sugere que esta diminuição se relacione com a ação anti-inflamatória de clusterina.