title: Effects of Heat Stress Treatment on Age-dependent Unfolded Protein Response in Different Types of Skeletal Muscle.
abstract: Mitochondrial and endoplasmic reticulum (ER) stress, and subsequently activated responses (mitochondrial/ER unfolded protein responses; UPRmt/UPRER), are involved in the pathogenesis of sarcopenia. To extend both basic and translational knowledge, we examined (i) whether age-induced mitochondrial and ER stress depend on skeletal muscle type in mice and (ii) whether heat stress treatment, a suggested strategy for sarcopenia, improves age-induced mitochondrial and ER stress. Aged (21-month-old) mice showed more severe mitochondrial stress and UPRmt than young (12-week-old) mice, based on increased oxidative stress, mitochondrial proteases, and mitochondrial E3 ubiquitin ligase. The aged mice also showed ER stress and UPRER, based on decreased ER enzymes and increased ER stress-related cell death. These changes were much more evident in soleus muscle than in gastrocnemius and plantaris muscles. After daily heat stress treatment (40 °C chamber for 30 minutes per day) for 4 weeks, mice showed remarkable improvements in age-related changes in soleus muscle. Heat stress had only minor effects in gastrocnemius and plantaris muscles. Based on these findings, age-associated mitochondrial stress, ER stress, and UPRmt/ER vary qualitatively with skeletal muscle type. Our results suggest a molecular basis for the beneficial effects of heat stress on muscle atrophy with age in soleus muscle.
authors.affiliation: Department of Sports Sciences, The University of Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Tamura
authors.affiliation: Department of Sports Sciences, The University of Tokyo, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Matsunaga
authors.affiliation: Department of Sports Sciences, The University of Tokyo, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Kitaoka
authors.affiliation: Department of Sports Sciences, The University of Tokyo, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Hatta
mesh_terms: D000367:Age Factors; D000818:Animals; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D018869:Heat-Shock Response; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008928:Mitochondria / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D056811:Unfolded Protein Response / Q000502:physiology*
keywords: Animal model; Heat/heat shock; Mitochondria; Oxidation/oxidative stress; Sarcopenia