The effect of short-term heat stress on protein synthesis signaling in isolated rat skeletal muscle

• Main Authors: Ayumi Goto, Keiichi Sekine, Rieko Oshima, Ichika Sakon, Mayu Iwamoto, Tomohiko Osaki, Kotaro Haga, Tatsuya Hayashi, Tatsuro Egawa
• Format: Article
• Language: English
• Published: Japanese Society of Physical Fitness and Sports Medicine 2018-01-01
• Series: Journal of Physical Fitness and Sports Medicine
• Subjects: hyperthermia; protein metabolism; autophagy; ubiquitin-proteasome system; exercise
• Online Access: https://www.jstage.jst.go.jp/article/jpfsm/7/1/7_87/_pdf/-char/en
• ISSN: 2186-8131; 2186-8123

Heat stress (HS) is a potent stimulus for activating glucose metabolism in skeletal muscles. However, the effect of short-term HS on protein turnover in skeletal muscles is unclear. This study aimed to investigate the effect of short-term HS on protein synthesis and protein degradation in skeletal muscles. The epitrochlearis muscle was isolated from male Sprague–Dawley rats weighing 150-160 grams (g) and incubated with or without HS at 42°C for 10 or 30 min in alpha minimum essential medium. HS for 30 min significantly decreased phosphorylation of 70-kDa ribosomal protein S6 kinase at Thr389 and 4E-binding protein 1 at Thr37/46. Correspondingly, HS for 30 min decreased the rate of protein synthesis. In contrast, HS had no effect on the expression of autophagy-related proteins, including microtubule-associated protein light chain 3 and p62, or on the mRNA expression of muscle-specific ubiquitin ligases, including muscle RING-finger 1 (MuRF1) and atrogin-1/MAFbx. These findings suggested that short-term HS for approximately 30 min is a physiologically relevant stimulus that suppresses protein synthesis signaling in skeletal muscles.