Role of dynamin‐related protein 1‐mediated mitochondrial fission in resistance of mouse C2C12 myoblasts to heat injury

Abstract

The regulation of mitochondrial morphology is closely coupled to cell survival during stress. We examined changes in the mitochondrial morphology of mouse C2C12 skeletal muscle cells in response to heat acclimation and heat shock exposure. Acclimated cells showed a greater survival rate during heat shock exposure than non-acclimated cells, and were characterized by long interconnected mitochondria and reduced expression of dynamin-related protein 1 (Drp1) for their mitochondrial fractions. Exposure of C2C12 muscle cells to heat shock led to apoptotic death featuring activation of caspase 3/7, release of cytochrome c and loss of cell membrane integrity. Heat shock also caused excessive mitochondrial fragmentation, loss of mitochondrial membrane potential and production of reactive oxygen species in C2C12 cells. Western blot and immunofluorescence image analysis revealed translocation of Drp1 to mitochondria from the cytosol in C2C12 cells exposed to heat shock. Mitochondrial division inhibitor 1 or Drp1 gene silencer reduced mitochondrial fragmentation and increased cell viability during exposure to heat shock. These results suggest that Drp1-dependent mitochondrial fission may regulate susceptibility to heat-induced apoptosis in muscle cells and that Drp1 may serve as a target for the prevention of heat-related injury.

Glucocorticoid receptor activation is associated with increased resistance to heat‐induced hyperthermia and injury

“…Similar changes were found in C2C12 mouse skeletal myoblasts following TA incubation, compared to control cells (Figure ). We have previously shown that TA incubation significantly increases C2C12 cell viability during heat exposure . To further verify the effects of TA on subcellular GR, we used fluorescence microscopy to investigate the nuclear and mitochondrial localization of GR in C2C12 mouse skeletal myoblasts following normal or TA incubations.…”

“…Elevation of body temperature substantially beyond the normal range is a major risk factor for injuries during heat exposure, and its prevention is crucial in surviving a lethal heat shock . Interestingly, the hyperthermic response to heat varies across individuals and thermal acclimation (TA) can lead to decreased hyperthermia and injury during heat exposure . Understanding the mechanisms that underlie resistance to heat‐induced hyperthermia and injury may help with developing strategies to reduce the risk of heat‐related illnesses.…”

Astaxanthin but not quercetin preserves mitochondrial integrity and function, ameliorates oxidative stress, and reduces heat‐induced skeletal muscle injury

“…Electron micrographs of mouse skeletal muscle showed that fragmented mitochondria in heatshocked muscle more frequently displayed lower cristae density and disorganized structure, which reflect mitochondrial dysfunction (Yu et al, 2016. Importantly, inhibition of fission not only restored all the changes in mitochondrial ultrastructure, but also prevented heatinduced mitochondrial dysfunction and cell injury (Yu et al, 2016.…”

“…Muscle cramping and pain are among the first symptoms of heat-related illness (Becker & Stewart, 2011;Nelson, Collins, Comstock, & McKenzie, 2011), thus skeletal muscle should be considered a primary target for mitigating heat stress. In adult mouse skeletal muscle and C2C12 myoblasts, heat exposure initiates a cascade of events that can induce apoptosis (Yu, Deuster, & Chen, 2016;Yu et al, 2018). Also, heat stress stimulates the production of reactive oxygen species (ROS) that can exceed cellular antioxidant capacity, which is believed to contribute to the onset of heat-related skeletal muscle injuries (Davidson, Whyte, Bissinger, & Schiestl, 1996;Montilla et al, 2014;Yu et al, 2016Yu et al, , 2018).…”

“…In adult mouse skeletal muscle and C2C12 myoblasts, heat exposure initiates a cascade of events that can induce apoptosis (Yu, Deuster, & Chen, 2016;Yu et al, 2018). Also, heat stress stimulates the production of reactive oxygen species (ROS) that can exceed cellular antioxidant capacity, which is believed to contribute to the onset of heat-related skeletal muscle injuries (Davidson, Whyte, Bissinger, & Schiestl, 1996;Montilla et al, 2014;Yu et al, 2016Yu et al, , 2018). The precise mechanisms of heat-related injuries, however, remain to be elucidated.…”