Examinando por Autor "Zbinden-Foncea, Hermann"
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Ítem A single bout of resistance exercise triggers mitophagy, potentially involving the ejection of mitochondria in human skeletal muscle(Wiley, 2024-09-24) Díaz-Castro, Francisco; Tuñón-Suárez, Mauro; Rivera, Patricia; Botella, Javier; Cancino, Jorge; Figueroa, Ana María; Gutiérrez, Juan; Cantin, Claudette; Deldicque, Louise; Zbinden-Foncea, Hermann; Nielsen, Joachim; Henríquez-Olguín, Carlos; Morselli, Eugenia; Castro-Sepulveda, MauricioAim The present study aimed to investigate the effects of a single bout of resistance exercise on mitophagy in human skeletal muscle (SkM). Methods Eight healthy men were recruited to complete an acute bout of one-leg resistance exercise. SkM biopsies were obtained one hour after exercise in the resting leg (Rest-leg) and the contracting leg (Ex-leg). Mitophagy was assessed using protein-related abundance, transmission electron microscopy (TEM), and fluorescence microscopy. Results Our results show that acute resistance exercise increased pro-fission protein phosphorylation (DRP1Ser616) and decreased mitophagy markers such as PARKIN and BNIP3L/NIX protein abundance in the Ex-leg. Additionally, mitochondrial complex IV decreased in the Ex-leg when compared to the Rest-leg. In the Ex-leg, TEM and immunofluorescence images showed mitochondrial cristae abnormalities, a mitochondrial fission phenotype, and increased mitophagosome-like structures in both subsarcolemmal and intermyofibrillar mitochondria. We also observed increased mitophagosome-like structures on the subsarcolemmal cleft and mitochondria in the extracellular space of SkM in the Ex-leg. We stimulated human primary myotubes with CCCP, which mimics mitophagy induction in the Ex-leg, and found that BNIP3L/NIX protein abundance decreased independently of lysosomal degradation. Finally, in another human cohort, we found a negative association between BNIP3L/NIX protein abundance with both mitophagosome-like structures and mitochondrial cristae density in the SkM. Conclusion The findings suggest that a single bout of resistance exercise can initiate mitophagy, potentially involving mitochondrial ejection, in human skeletal muscle. BNIP3L/NIX is proposed as a sensitive marker for assessing mitophagy flux in SkM.Ítem BMAL1 and CLOCK proteins exhibit differential association with mitochondrial dynamics, protein synthesis pathways and muscle strength in human muscle(The Physiological Society, 2024-06-26) Figueroa-Toledo, A. M.; Gutiérrez-Pino, J.; Carriel-Nesvara, A.; Marchese-Bittencourt, M.; Zbinden-Foncea, Hermann; Castro-Sepulveda, MauricioMurine models lacking CLOCK/BMAL1 proteins in skeletal muscle (SkM) present muscle deterioration and mitochondria abnormalities. It is unclear whether humans with lower levels of these proteins in the SkM have similar alterations. Here we evaluated the association between BMAL1 and CLOCK protein mass with mitochondrial dynamics parameters and molecular and functional SkM quality markers in males. SkM biopsies were taken from the vastus lateralis of 16 male (non-athletes, non-obese and non-diabetic) subjects (8–9 a.m.). The morphology of mitochondria and their interaction with the sarcoplasmic reticulum (mitochondria-SR) were determined using transmission electron microscopy images. Additionally, protein abundance of the OXPHOS complex, mitochondria fusion/fission regulators, mitophagy and signalling proteins related to muscle protein synthesis were measured. To evaluate the quality of SkM, the cross-sectional area and maximal SkM strength were also measured. The results showed that BMAL1 protein mass was positively associated with mitochondria-SR distance, mitochondria size, mitochondria cristae density and mTOR protein mass. On the other hand, CLOCK protein mass was negatively associated with mitochondria-SR interaction, but positively associated with mitochondria complex III, OPA1 and DRP1 protein mass. Furthermore, CLOCK protein mass was positively associated with the protein synthesis signalling pathway (total mTOR, AKT and P70S6K protein mass) and SkM strength. These findings suggest that the BMAL1 and CLOCK proteins play different roles in regulating mitochondrial dynamics and SkM function in males, and that modulation of these proteins could be a potential therapeutic target for treating muscle diseases.Ítem Effects of an antioxidants cocktail on glucose metabolism at rest, during exercise, and during a glucose load in healthy young subjects(Sociedad Chilena de Nutrición, Bromatología y Toxicología, 2023-12-15) Rodríguez, Ivan; Paez Espinosa, Enma Verónica; Zbinden-Foncea, Hermann; Echeverria, Francisca; Castro-Sepulveda, MauricioBackground: Reactive oxygen species (ROS) regulate glucose metabolism (GM) in skeletal muscle by improving the translocation of GLUT4. Antioxidant supplementation could block this physiological effect, altering glucose signaling during exercise. However, there is limited evidence in humans on whether antioxidant intake affects GM. Therefore, we aimed to determine the effect of an antioxidant cocktail (AOC) on GM at rest and during metabolic challenges. Methods: Ten healthy male subjects received AOC supplementation (1000 mg of Vitamin C, 600 IU of Vitamin E, and 600 mg of α-lipoic acid) or placebo (2.000 mg of talc) before two trials conducted 7 days apart. Trial 1: AOC 120 and 90 minutes before an endurance exercise (EEX) bout at 60 % of maximal oxygen uptake (VO2max); Trial 2: AOC 120 and 90 minutes before an oral glucose tolerance test (OGTT; 75 g glucose). Measurements of gas exchange and capillary blood samples were collected every 15 minutes during both trials. Results: AOC supplementation increased resting glucose levels (p<0.05). During Trial 1 (EEX), the AOC increased carbohydrate oxidation (CHOox) (p= 0.03), without effect in glucose blood levels. During Trial 2 (OGTT), the AOC supplementation had no significant effect on GM parameters. Conclusion: Acute supplementation with AOC increased resting glucose levels and CHOox during EEX in healthy subjects, with no effect on GM during the OGTT.Ítem The fasting-feeding metabolic transition regulates mitochondrial dynamics(Federation of American Society of Experimental Biology (FASEB), 2021-10-10) Castro-Sepulveda, Mauricio; Morio, Béatrice; Tuñón-Suárez, Mauro; Jannas-Vela, Sebastian; Díaz-Castro, Francisco; Rieusset, Jennifer; Zbinden-Foncea, HermannIn humans, insulin resistance has been linked to an impaired metabolic transition from fasting to feeding (metabolic flexibility; MetFlex). Previous studies suggest that mitochondrial dynamics response is a putative determinant of MetFlex; however, this has not been studied in humans. Thus, the aim of this study was to investigate the mitochondrial dynamics response in the metabolic transition from fasting to feeding in human peripheral blood mononuclear cells (PBMCs). Six male subjects fasted for 16 h (fasting), immediately after which they consumed a 75-g oral glucose load (glucose). In both fasting and glucose conditions, blood samples were taken to obtain PBMCs. Mitochondrial dynamics were assessed by electron microscopy images. We exposed in vitro acetoacetate-treated PBMCs to the specific IP3R inhibitor Xestospongin B (XeB) to reduce IP3R-mediated mitochondrial Ca2+ accumulation. This allowed us to evaluate the role of ER-mitochondria Ca2+ exchange in the mitochondrial dynamic response to substrate availability. To determine whether PBMCs could be used in obesity context (low MetFlex), we measured mitochondrial dynamics in mouse spleen-derived lymphocytes from WT and ob/ob mice. We demonstrated that the transition from fasting to feeding reduces mitochondria-ER interactions, induces mitochondrial fission and reduces mitochondrial cristae density in human PBMCs. In addition, we demonstrated that IP3R activity is key in the mitochondrial dynamics response when PBMCs are treated with a fasting-substrate in vitro. In murine mononuclear-cells, we confirmed that mitochondria-ER interactions are regulated in the fasted-fed transition and we further highlight mitochondria-ER miscommunication in PBMCs of diabetic mice. In conclusion, our results demonstrate that the fasting/feeding transition reduces mitochondria-ER interactions, induces mitochondrial fission and reduces mitochondrial cristae density in human PBMCs, and that IP3R activity may potentially play a central role.Ítem Low abundance of Mfn2 protein correlates with reduced mitochondria-SR juxtaposition and mitochondrial cristae density in human men skeletal muscle: Examining organelle measurements from TEM images(Wiley Open Access, 2021-03-08) Castro-Sepulveda, Mauricio; Fernández-Verdejo, Rodrigo; Tuñón-Suárez, Mauro; Morales-Zúñiga, Jorge; Troncoso, Mayarling; Jannas-Vela, Sebastian; Zbinden-Foncea, HermannThe role of mitofusin 2 (Mfn2) in the regulation of skeletal muscle (SM) mitochondria-sarcoplasmic (SR) juxtaposition, mitochondrial morphology, mitochondrial cristae density (MCD), and SM quality has not been studied in humans. In in vitro studies, whether Mfn2 increases or decreases mitochondria-SR juxtaposition remains controversial. Transmission electron microscopy (TEM) images are commonly used to measure the organelle juxtaposition, but the measurements are performed "by-hand," thus potentially leading to between-rater differences. The purposes of this study were to: (1) examine the repeatability and reproducibility of mitochondrial-SR juxtaposition measurement from TEM images of human SM between three raters with different experience and (2) compare the mitochondrial-SR juxtaposition, mitochondrial morphology, MCD (stereological-method), and SM quality (cross-sectional area [CSA] and the maximum voluntary contraction [MVC]) between subjects with high abundance (Mfn2-HA; n = 6) and low abundance (Mfn2-LA; n = 6) of Mfn2 protein. The mitochondria-SR juxtaposition had moderate repeatability and reproducibility, with the most experienced raters showing the best values. There were no differences between Mfn2-HA and Mfn2-LA groups in mitochondrial size, distance from mitochondria to SR, CSA, or MVC. Nevertheless, the Mfn2-LA group showed lower mitochondria-SR interaction, MCD, and VO2max . In conclusion, mitochondrial-SR juxtaposition measurement depends on the experience of the rater, and Mfn2 protein seems to play a role in the metabolic control of human men SM, by regulating the mitochondria-SR interaction.Ítem Mitochondria-SR interaction and mitochondrial fusion/fission in the regulation of skeletal muscle metabolism(Elsevier, 2023-07-01) Castro-Sepulveda, Mauricio; Fernández-Verdejo, Rodrigo; Zbinden-Foncea, Hermann; Rieusset, JenniferMitochondria-endoplasmic/sarcoplasmic reticulum (ER/SR) interaction and mitochondrial fusion/fission are critical processes that influence substrate oxidation. This narrative review summarizes the evidence on the effects of substrate availability on mitochondrial-SR interaction and mitochondria fusion/fission dynamics to modulate substrate oxidation in human skeletal muscle. Evidence shows that an increase in mitochondria-SR interaction and mitochondrial fusion are associated with elevated fatty acid oxidation. In contrast, a decrease in mitochondria-SR interaction and an increase in mitochondrial fission are associated with an elevated glycolytic activity. Based on the evidence reviewed, we postulate two hypotheses for the link between mitochondrial dynamics and insulin resistance in human skeletal muscle. First, glucose and fatty acid availability modifies mitochondria-SR interaction and mitochondrial fusion/fission to help the cell to adapt substrate oxidation appropriately. Individuals with an impaired response to these substrate challenges will accumulate lipid species and develop insulin resistance in skeletal muscle. Second, a chronically elevated substrate availability (e.g. overfeeding) increases mitochondrial production of reactive oxygen species and induced mitochondrial fission. This decreases fatty acid oxidation, thus leading to the accumulation of lipid species and insulin resistance in skeletal muscle. Altogether, we propose mitochondrial dynamics as a potential target for disturbances associated with low fatty acid oxidation.Ítem A mutation in desmin makes skeletal muscle less vulnerable to acute muscle damage after eccentric loading in rats(Wiley; Federation of American Societies for Experimental Biology, 2021-09-01) Langer, Henning T.; Mossakowski, Agata A.; Avey, Alec M.; Wohlgemuth, Ross P.; Smith, Lucas R.; Zbinden-Foncea, Hermann; Baar, KeithDesminopathy is the most common intermediate filament disease in humans. The most frequent mutation causing desminopathy in patients is a R350P DES missense mutation. We have developed a rat model with an analogous mutation in R349P Des. To investigate the role of R349P Des in mechanical loading, we stimulated the sciatic nerve of wild-type littermates (WT) (n = 6) and animals carrying the mutation (MUT) (n = 6) causing a lengthening contraction of the dorsi flexor muscles. MUT animals showed signs of ongoing regeneration at baseline as indicated by a higher number of central nuclei (genotype: P < .0001). While stimulation did not impact central nuclei, we found an increased number of IgG positive fibers (membrane damage indicator) after eccentric contractions with both genotypes (stimulation: P < .01). Interestingly, WT animals displayed a more pronounced increase in IgG positive fibers with stimulation compared to MUT (interaction: P < .05). In addition to altered histology, molecular signaling on the protein level differed between WT and MUT. The membrane repair protein dysferlin decreased with eccentric loading in WT but increased in MUT (interaction: P < .05). The autophagic substrate p62 was increased in both genotypes with loading (stimulation: P < .05) but tended to be more elevated in WT (interaction: P = .05). Caspase 3 levels, a central regulator of apoptotic cell death, was increased with stimulation in both genotypes (stimulation: P < .01) but more so in WT animals (interaction: P < .0001). Overall, our data indicate that R349P Des rats have a lower susceptibility to structural muscle damage of the cytoskeleton and sarcolemma with acute eccentric loading.Ítem Regulation of mitochondrial morphology and cristae architecture by the TLR4 pathway in human skeletal muscle(Frontiers Media S.A., 2023-06-25) Castro-Sepulveda, Mauricio; Tuñón-Suárez, Mauro; Rosales-Soto, Giovanni; Vargas-Foitzick, Ronald; Deldicque, Louise; Zbinden-Foncea, HermannIn skeletal muscle (SkM), a reduced mitochondrial elongate phenotype is associated with several metabolic disorders like type 2 diabetes mellitus (T2DM). However, the mechanisms contributing to this reduction in mitochondrial elongate phenotype in SkM have not been fully elucidated. It has recently been shown in a SkM cell line that toll-like receptor 4 (TLR4) contributes to the regulation of mitochondrial morphology. However, this has not been investigated in human SkM. Here we found that in human SkM biopsies, TLR4 protein correlated negatively with Opa1 (pro-mitochondrial fusion protein). Moreover, the incubation of human myotubes with LPS reduced mitochondrial size and elongation and induced abnormal mitochondrial cristae, which was prevented with the co-incubation of LPS with TAK242. Finally, T2DM myotubes were found to have reduced mitochondrial elongation and mitochondrial cristae density. Mitochondrial morphology, membrane structure, and insulin-stimulated glucose uptake were restored to healthy levels in T2DM myotubes treated with TAK242. In conclusion, mitochondrial morphology and mitochondrial cristae seem to be regulated by the TLR4 pathway in human SkM. Those mitochondrial alterations might potentially contribute to insulin resistance in the SkM of patients with T2DM.Ítem Severe COVID-19 correlates with lower mitochondrial cristae density in PBMCs and greater sitting time in humans(Wiley; The Physiological Society and the American Physiological Society, 2022-05-27) Castro-Sepulveda, Mauricio; Tapia, German; Tuñón-Suárez, Mauro; Marambio, Hugo; Valero-Breton, Mayalen; Fernández-Verdejo, Rodrigo; Zbinden-Foncea, HermannAn interaction between mitochondrial dynamics, physical activity levels, andCOVID-19 severity has been previously hypothesized. However, this has notbeen tested. We aimed to compare mitochondrial morphology and cristae den-sity of PBMCs between subjects with non- severe COVID- 19, subjects with se-vere COVID- 19, and healthy controls. Additionally, we compared the level ofmoderate-vigorous physical activity (MVPA) and sitting time between groups.Blood samples were taken to obtain PBMCs. Mitochondrial dynamics were as-sessed by electron microscopy images and western blot of protein that regulatemitochondrial dynamics. The International Physical Activity Questionnaire(IPAQ; short version) was used to estimate the level of MVPA and the sitting timeThe patients who develop severe COVID-19 (COVID-19++) not present altera-tions of mitochondrial size neither mitochondrial density in comparison to non-severe patients COVID- 19 (COVID- 19) and control subjects (CTRL). However,compared to CTRL, COVID- 19 and COVID-19++ groups have lower mitochon-drial cristae length, a higher proportion of abnormal mitochondrial cristae. TheCOVID-19++ group has lower number (trend) and length of mitochondrial cris-tae in comparison to COVID- 19 group. COVID- 19, but not COVID- 19++ grouphad lower Opa 1, Mfn 2 and SDHB (Complex II) proteins than CTRL group.Besides, COVID-19++ group has a higher time sitting. Our results show that lowmitochondrial cristae density, potentially due to physical inactivity, is associatedwith COVID-19 severity.