Possible Role of NF-ĸB Signals in Heat Stress-Associated Increase in Protein Content of Cultured C2C12 Cells

Abstract

Heat stress is one of the hypertrophic stimuli on mammalian skeletal muscle. Nuclear factor-ĸB (NF-ĸB) signaling plays an important role in the regulation of skeletal muscle mass. However, the effects of heat stress on NF-ĸB signaling in skeletal muscle cells remain unclear. Effects of heat stress and/or administration of BAY11-7082, an inhibitor of NF-ĸB, on NF-ĸB signals and protein content of skeletal muscle were studied by using cell culture system. Differentiated mouse myoblasts (C2C12) were subjected to either (1) control (cultured at 37°C without BAY11-7082), (2) heat stress at 41°C for 60 min, (3) BAY11-7082 administration (1.25 µM) or (4) heat stress combined with BAY11-7082 administration. Heat shock protein 72 (HSP72) was upregulated by heat stress with or without administration of BAY11-7082. The increase in inhibitor of ĸBα (IĸBα), which regulates the phosphorylation of NF-ĸB, and the decrease in phosphorylated NF-ĸB were also induced by administration of BAY11-7082 and/or heat stress. Protein content in C2C12 cells was increased by the administration of BAY11-7082 with a semi-logarithm fashion. Significant increases in the protein content of C2C12 cells were observed 48 h following heating with or without administration of BAY11-7082. These observations suggest that heat stress might increase muscle protein through the downregulation of NF-ĸB signaling. Inhibition of NF-ĸB induced by application of heat stress might be one of the hypertrophic stimuli on skeletal muscle cells.

AICAR-induced activation of AMPK negatively regulates myotube hypertrophy through the HSP72-mediated pathway in C2C12skeletal muscle cells

“…Cell culture was performed as we described previously (11,33). Mouse myoblast C 2C12 cells were cultured on six-well culture plates with type I collagen-coated surface (Biocoat; BectonDeckinson Labware, Franklin Lakes, NJ).…”

“…Sample preparation was performed with some modification of the previously reported method (33). Briefly, the cells in each well were rinsed twice with 1 ml of ice-cold phosphatebuffered saline.…”

“…Western blot analysis was performed as was described previously (5,33). Extracted samples in the cell lysis reagents were solubilized in Laemmli's sample buffer and boiled for 5 min.…”

The effects of acute oral glutamine supplementation on exercise-induced gastrointestinal permeability and heat shock protein expression in peripheral blood mononuclear cells

“…The mechanism of cytokine inhibition may be through activation of the heat shock response leading to inactivation of the NF-κB inflammatory pathway (Dokladny et al 2010;Paimela et al 2011). In this model, upregulation of heat shock factor-1 (HSF-1) and heat shock protein 70 or HSP70 (HSPA1A/B) (Kampinga et al 2009) prevented phosphorylation of nuclear factor of kappalight-polypeptide gene enhancer in B cells inhibitor, alpha (IκBα) leading to cytosolic housing of NF-κB (Dokladny et al 2010;Ohno et al 2011). We have previously demonstrated that 7 days of glutamine supplementation upregulated HSP70 and increased de-phosphorylated IκBα in PBMCs, along with preventing intestinal permeability in response to exercise.…”

Head-out immersion in hot water does not increase serum CXCL1 in healthy men

“…Moreover, they strongly suggested that the NF-κB signaling pathway is directly involved in CXCL1 expression in response to EPS-evoked contractility [19] . However, NF-κB signaling was reported to be downregulated by hyperthermia in mouse myoblast cells [20] . These results of the above studies might explain the lack of change in serum CXCL1 level and the increase in serum IL-6 level after hot-HOI.…”