Cells at the far right were stained with anti-myosin heavy chain antibody (MF20, Developmental Studies Hybridoma Bank, University of Iowa, Iowa City, IA). (D) Relative expression levels of myogenin ...(Myog), myosin heavy chain 3 (Myh3), myoglobin (Mb), troponin T type 1 (Tnnt1) and 3 (Tnnt3), and creatine kinase, muscle (Ckm) mRNAs at 0, 24, 48, and 72 h of differentiation.
Issue Information
The FEBS journal,
10/2023, Volume:
290, Issue:
19
Journal Article
Peer reviewed
Cover Illustration FKBP25 is ubiquitously expressed throughout the cytoplasm and nucleus of C2C12 myotubes (Blue: Nuclei, Red: FKBP25). Cover image is from the study by Tabitha Cree, John T. Price, ...Craig A. Goodman and colleagues included in this issue, pages 4660–4678.
4′-Methyl-4,5′-bithiazoles were previously identified as cystic fibrosis transmembrane regulator (CFTR) correctors, thus being able to correct folding defective mutants of the channel regulating ...chloride transport through the membrane. Additionally, bithiazole derivative C17 was reported to recover α-sarcoglycan in vitro and in vivo. We report here the synthesis of two new derivatives of C17, in which the two sides of the bithiazole scaffold were modified. The synthesized compounds and the corresponding precursors were tested in myogenic cells to evaluate the expression of α-sarcoglycan. The results highlighted that both substitutions of the bithiazole scaffold are important to achieve the maximum recovery of the α-sarcoglycan mutant. Nonetheless, partial preservation of the activity was observed. Accordingly, this paves the way to further derivatizations/optimization and target fishing studies, which were preliminarily performed in this study as a proof of concept, allowing the investigation of the molecular mechanisms leading to the α-sarcoglycan correction.
Circadian clocks play an important role in lipid homeostasis, with impact on various metabolic diseases. Due to the central role of skeletal muscle in whole-body metabolism, we aimed at studying ...muscle lipid profiles in a temporal manner. Moreover, it has not been shown whether lipid oscillations in peripheral tissues are driven by diurnal cycles of rest–activity and food intake or are able to persist in vitro in a cell-autonomous manner. To address this, we investigated lipid profiles over 24 h in human skeletal muscle in vivo and in primary human myotubes cultured in vitro. Glycerolipids, glycerophospholipids, and sphingolipids exhibited diurnal oscillations, suggesting a widespread circadian impact on muscle lipid metabolism. Notably, peak levels of lipid accumulation were in phase coherence with core clock gene expression in vivo and in vitro. The percentage of oscillating lipid metabolites was comparable between muscle tissue and cultured myotubes, and temporal lipid profiles correlated with transcript profiles of genes implicated in their biosynthesis. Lipids enriched in the outer leaflet of the plasma membrane oscillated in a highly coordinated manner in vivo and in vitro. Lipid metabolite oscillations were strongly attenuated upon siRNA-mediated clock disruption in human primary myotubes. Taken together, our data suggest an essential role for endogenous cell-autonomous human skeletal muscle oscillators in regulating lipid metabolism independent of external synchronizers, such as physical activity or food intake.
Exposure to bisphenol A (BPA) is associated with insulin resistance and type 2 diabetes (T2D). Since muscle insulin resistance is the primary defect in T2D, we aimed to determine whether BPA alters ...glucose metabolism in L6 muscle cells. L6 or L6-GLUT4-myc cells were exposed to 1–104 nM BPA or the vehicle (0.1% DMSO) for 7 days. BPA at 103-104 nM significantly decreased the levels of the muscle differentiation markers troponin- T and myosin heavy chain 3. Insulin-stimulated phosphorylation of Akt and GSK3, insulin-stimulated glucose uptake, and insulin-stimulated GLUT4 translocation were significantly decreased with 103-104 nM BPA. Basal glucose uptake and glycolysis (extracellular acidification rates measured by Seahorse XFe96) were increased with 103-104 nM BPA. Levels of ROS detoxifying enzymes were increased with BPA >10 nM, while catalase activity was increased with 103-104 nM BPA. However, BPA did not induce oxidative stress (measured by protein carbonylation and lipid peroxidation) nor mitochondrial dysfunction. The effects of BPA on basal glucose uptake and catalase activity, but not on insulin sensitivity, were restored when estrogen receptors (ERs) were inhibited with ICI. These findings suggest that high concentrations of BPA increase muscle glucose uptake through the ERs but induce insulin resistance through another pathway.
•BPA above 103 nM decreases insulin sensitivity in L6 myotubes.•BPA above 103 nM increases basal glucose uptake and glycolysis in L6 myotubes.•The increased glucose metabolism by BPA is dependent on the estrogen receptors.•BPA above 10 nM increases the levels of anti-oxidant enzymes in L6 myotubes.•The increased catalase activity by BPA is dependent on the estrogen receptors.
Recently, cultured meat obtained from livestock‐derived cells is being considered as a sustainable food source that reduces the use of natural resources. This study aimed to show that nutrients ...extracted from Chlorella vulgaris were beneficial in the culture of primary bovine myoblasts (PBMs), a major cell source for cultured meat production. Nutrients (glucose, amino acids, and vitamins) present in the animal‐cell culture media were effectively recovered from C. vulgaris using acid hydrolysis treatment. On culture in nutrient‐free inorganic salt solution, cell death was induced in most PBMs after 6 days of cultivation. However, the addition of C. vulgaris extract (CVE) significantly improved PBM viability, which was comparable to the viability in conventional culture medium (Dulbecco's modified Eagle's medium). Furthermore, by adding horse serum to induce differentiation, the formation of myotubes was confirmed when CVE were used. Together, the results showed that CVE could be used as an alternative to the conventional culture medium for PBMs. These findings will not only lower the environmental risks associated with the establishment of this eco‐friendly cell culture system, but also highlight microalgae as a potent nutrient source that can replace conventional grain‐dependent nutrient sources.
Insulin resistance in skeletal muscle is a major risk factor for the development of type 2 diabetes in women with polycystic ovary syndrome (PCOS). Despite this, the mechanisms underlying insulin ...resistance in PCOS are largely unknown.
To investigate the genome-wide DNA methylation and gene expression patterns in skeletal muscle from women with PCOS and controls and relate them to phenotypic variations.
In a case-control study, skeletal muscle biopsies from women with PCOS (n = 17) and age-, weight-, and body mass index‒matched controls (n = 14) were analyzed by array-based DNA methylation and mRNA expression profiling.
Eighty-five unique transcripts were differentially expressed in muscle from women with PCOS vs controls, including DYRK1A, SYNPO2, SCP2, and NAMPT. Furthermore, women with PCOS had reduced expression of genes involved in immune system pathways. Two CpG sites showed differential DNA methylation after correction for multiple testing. However, an mRNA expression of ∼30% of the differentially expressed genes correlated with DNA methylation levels of CpG sites in or near the gene. Functional follow-up studies demonstrated that KLF10 is under transcriptional control of insulin, where insulin promotes glycogen accumulation in myotubes of human muscle cells. Testosterone downregulates the expression levels of COL1A1 and MAP2K6.
PCOS is associated with aberrant skeletal muscle gene expression with dysregulated pathways. Furthermore, we identified specific changes in muscle DNA methylation that may affect gene expression. This study showed that women with PCOS have epigenetic and transcriptional changes in skeletal muscle that, in part, can explain the metabolic abnormalities seen in these women.
The role of autophagy and lysosomal degradation pathway in the regulation of skeletal muscle metabolism was previously studied. However, underlying molecular mechanisms are poorly understood. ...L-lactate which is utilized as an energetic substrate by skeletal muscle can also augment genes expression related to metabolism and up-regulate those being responsive to reactive oxygen species (ROS). Since ROS is the most important regulator of autophagy in skeletal muscle, we tested if there is a link between cellular lactate metabolism and autophagy in differentiated C2C12 myotubes and the gastrocnemius muscle of male wistar rats. C2C12 mouse skeletal muscle was exposed to 2, 6, 10, and 20 mM lactate and evaluated for lactate autophagic effects. Lactate dose-dependently increased autophagy and augmented ROS generation in differentiated C2C12 myotubes. The autophagic effect of lactate deterred in N-acetylcysteine presence (NAC, a ROS scavenger) indicated lactate regulates autophagy with ROS participation. Lactate-induced up-regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) through ROS was required to regulate the autophagy by lactate. Further analysis about ERK1/2 up- and downstream indicated that lactate regulates autophagy through ROS-mediated the activation of ERK1/2/mTOR/p70S6K pathway in skeletal muscle. The in vitro effects of lactate on autophagy also occurred in the gastrocnemius muscle of male Wistar rats. In conclusion, we provided the lactate-associated regulation evidence of autophagy in skeletal muscle by activating ROS-mediated ERK1/2/mTOR/p70S6K pathway. Since the increase in cellular lactate concentration is a hallmark of energy deficiency, the results provide insight into a skeletal muscle mechanism to fulfill its enhanced energy requirement.
Human behaviors are extremely sophisticated, relying on the adaptive, plastic and event-driven network of sensory neurons. Such neuronal system analyzes multiple sensory cues efficiently to establish ...accurate depiction of the environment. Here, we develop a bimodal artificial sensory neuron to implement the sensory fusion processes. Such a bimodal artificial sensory neuron collects optic and pressure information from the photodetector and pressure sensors respectively, transmits the bimodal information through an ionic cable, and integrates them into post-synaptic currents by a synaptic transistor. The sensory neuron can be excited in multiple levels by synchronizing the two sensory cues, which enables the manipulating of skeletal myotubes and a robotic hand. Furthermore, enhanced recognition capability achieved on fused visual/haptic cues is confirmed by simulation of a multi-transparency pattern recognition task. Our biomimetic design has the potential to advance technologies in cyborg and neuromorphic systems by endowing them with supramodal perceptual capabilities.
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