Browsing by Subject "Myoblasts"

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemUnknown
    Curcumin Ameliorates Heat-Induced Injury through NADPH Oxidase-Dependent Redox Signaling and Mitochondrial Preservation in C2C12 Myoblasts and Mouse Skeletal Muscle.
    (The Journal of nutrition, 2020-09) Yu, Tianzheng; Dohl, Jacob; Wang, Li; Chen, Yifan; Gasier, Heath G; Deuster, Patricia A

    Background

    Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and the mitochondrial electron transport chain are the primary sources of reactive oxygen species (ROS). Previous studies have shown that severe heat exposure damages mitochondria and causes excessive mitochondrial ROS production that contributes to the pathogenesis of heat-related illnesses.

    Objectives

    We tested whether the antioxidant curcumin could protect against heat-induced mitochondrial dysfunction and skeletal muscle injury, and characterized the possible mechanism.

    Methods

    Mouse C2C12 myoblasts and rat flexor digitorum brevis (FDB) myofibers were treated with 5 μM curcumin; adult male C57BL/6J mice received daily curcumin (15, 50, or 100 mg/kg body weight) by gavage for 10 consecutive days. We compared ROS levels and mitochondrial morphology and function between treatment and nontreatment groups under unheated or heat conditions, and investigated the upstream mechanism and the downstream effect of curcumin-regulated ROS production.

    Results

    In C2C12 myoblasts, curcumin prevented heat-induced mitochondrial fragmentation, ROS overproduction, and apoptosis (all P < 0.05). Curcumin treatment for 2 and 4 h at 37°C induced increases in ROS levels by 42% and 59% (dihydroethidium-derived fluorescence), accompanied by increases in NADPH oxidase protein expression by 24% and 32%, respectively (all P < 0.01). In curcumin-treated cells, chemical inhibition and genetic knockdown of NADPH oxidase restored ROS to levels similar to those of controls, indicating NADPH oxidase mediates curcumin-stimulated ROS production. Moreover, curcumin induced ROS-dependent shifting of the mitochondrial fission-fusion balance toward fusion, and increases in mitochondrial mass by 143% and membrane potential by 30% (both P < 0.01). In rat FDB myofibers and mouse gastrocnemius muscles, curcumin preserved mitochondrial morphology and function during heat stress, and prevented heat-induced mitochondrial ROS overproduction and tissue injury (all P < 0.05).

    Conclusions

    Curcumin regulates ROS hormesis favoring mitochondrial fusion/elongation, biogenesis, and improved function in rodent skeletal muscle. Curcumin may be an effective therapeutic target for heat-related illness and other mitochondrial diseases.
  • Thumbnail Image
    ItemUnknown
    Skeletal muscle mitochondrial fragmentation and impaired bioenergetics from nutrient overload are prevented by carbon monoxide.
    (American journal of physiology. Cell physiology, 2020-10) Gasier, Heath G; Dohl, Jacob; Suliman, Hagir B; Piantadosi, Claude A; Yu, Tianzheng
    Nutrient excess increases skeletal muscle oxidant production and mitochondrial fragmentation that may result in impaired mitochondrial function, a hallmark of skeletal muscle insulin resistance. This led us to explore whether an endogenous gas molecule, carbon monoxide (CO), which is thought to prevent weight gain and metabolic dysfunction in mice consuming high-fat diets, alters mitochondrial morphology and respiration in C2C12 myoblasts exposed to high glucose (15.6 mM) and high fat (250 µM BSA-palmitate) (HGHF). Also, skeletal muscle mitochondrial morphology, distribution, respiration, and energy expenditure were examined in obese resistant (OR) and obese prone (OP) rats that consumed a high-fat and high-sucrose diet for 10 wk with or without intermittent low-dose inhaled CO and/or exercise training. In cells exposed to HGHF, superoxide production, mitochondrial membrane potential (ΔΨm), mitochondrial fission regulatory protein dynamin-related protein 1 (Drp1) and mitochondrial fragmentation increased, while mitochondrial respiratory capacity was reduced. CO decreased HGHF-induced superoxide production, Drp1 protein levels and mitochondrial fragmentation, maintained ΔΨm, and increased mitochondrial respiratory capacity. In comparison with lean OR rats, OP rats had smaller skeletal muscle mitochondria that contained disorganized cristae, a normal mitochondrial distribution, but reduced citrate synthase protein expression, normal respiratory responses, and a lower energy expenditure. The combination of inhaled CO and exercise produced the greatest effect on mitochondrial morphology, increasing ADP-stimulated respiration in the presence of pyruvate, and preventing a decline in resting energy expenditure. These data support a therapeutic role for CO and exercise in preserving mitochondrial morphology and respiration during metabolic overload.
  • Thumbnail Image
    ItemUnknown
    VCP/p97 is essential for maturation of ubiquitin-containing autophagosomes and this function is impaired by mutations that cause IBMPFD.
    (Autophagy, 2010-02) Tresse, Emilie; Salomons, Florian A; Vesa, Jouni; Bott, Laura C; Kimonis, Virginia; Yao, Tso-Pang; Dantuma, Nico P; Taylor, J Paul
    VCP (VCP/p97) is a ubiquitously expressed member of the AAA(+)-ATPase family of chaperone-like proteins that regulates numerous cellular processes including chromatin decondensation, homotypic membrane fusion and ubiquitin-dependent protein degradation by the proteasome. Mutations in VCP cause a multisystem degenerative disease consisting of inclusion body myopathy, Paget disease of bone, and frontotemporal dementia (IBMPFD). Here we show that VCP is essential for autophagosome maturation. We generated cells stably expressing dual-tagged LC3 (mCherry-EGFP-LC3) which permit monitoring of autophagosome maturation. We determined that VCP deficiency by RNAi-mediated knockdown or overexpression of dominant-negative VCP results in significant accumulation of immature autophagic vesicles, some of which are abnormally large, acidified and exhibit cathepsin B activity. Furthermore, expression of disease-associated VCP mutants (R155H and A232E) also causes this autophagy defect. VCP was found to be essential to autophagosome maturation under basal conditions and in cells challenged by proteasome inhibition, but not in cells challenged by starvation, suggesting that VCP might be selectively required for autophagic degradation of ubiquitinated substrates. Indeed, a high percentage of the accumulated autophagic vesicles contain ubiquitin-positive contents, a feature that is not observed in autophagic vesicles that accumulate following starvation or treatment with Bafilomycin A. Finally, we show accumulation of numerous, large LAMP-1 and LAMP-2-positive vacuoles and accumulation of LC3-II in myoblasts derived from patients with IBMPFD. We conclude that VCP is essential for maturation of ubiquitin-containing autophagosomes and that defect in this function may contribute to IBMPFD pathogenesis.