title: Loading-associated expression of TRIM72 and caveolin-3 in antigravitational soleus muscle in mice.
abstract: Effects of mechanical loading on the expression level of tripartite motif-containing 72 (TRIM72) and caveolin-3 (Cav-3) in mouse soleus muscle were investigated. Mice were subjected to (1) continuous hindlimb suspension (HS) for 2 weeks followed by 1-week ambulation recovery or (2) functional overloading (FO) on the soleus by cutting the distal tendons of the plantaris and gastrocnemius muscles. Soleus muscle atrophy was induced by 2-week hindlimb suspension (HS). Reloading-associated regrowth of atrophied soleus muscle was observed by 1-week reloading following HS. HS also depressed the expression level of insulin receptor substrate-1 (IRS-1) mRNA, TRIM72, Cav-3, and phosphorylated Akt (p-Akt)/total Akt (t-Akt), but increased the phosphorylated level of p38 mitogen-activated protein kinase (p-p38MAPK) in soleus muscle. Thereafter, the expression level of MyoD mRNA, TRIM72 (mRNA, and protein), and Cav-3 was significantly increased and recovered to the basal level during 1-week reloading after HS. Although IRS-1 expression was also upregulated by reloading, the expression level was significantly lower than that before HS. Significant increase in p-Akt and phosphorylated p70 S6 kinase (p-p70S6K) was observed by 1-day reloading. On the other hand, 1-week functional overloading (FO) induced soleus muscle hypertrophy. In FO-associated hypertrophied soleus muscle, the expression level of IRS-1 mRNA, MyoD mRNA, TRIM72 mRNA, p-Akt, and p-p70S6K was increased, but the expression of Cav-3 and p-p38MAPK was decreased. FO had no effect on the protein expression level of TRIM72. These observations suggest that the loading-associated upregulation of TRIM72 protein in skeletal muscle may depress the regrowth of atrophied muscle via a partial suppression of IRS-1. In addition, downregulation of Cav-3 in skeletal muscle may depress overloading-induced muscle hypertrophy.
authors.affiliation: Laboratory of Physiology, School of Health Sciences, Toyohashi SOZO University, Toyohashi, 440-8511, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: Faculty of Education, Yamaguchi University, Yamaguchi, 753-8513, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Sugiura
authors.affiliation: Faculty and Graduate School of Health and Sports Sciences, Doshisha University, Kyotanabe, 610-0394, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ohira
authors.affiliation: Hirosaki Gakuin University, Hirosaki, 036-8577, Japan.
authors.forename: Toshitada
authors.initials: T
authors.lastname: Yoshioka
authors.affiliation: Laboratory of Physiology, School of Health Sciences, Toyohashi SOZO University, Toyohashi, 440-8511, Japan Department of Physiology, Graduate School of Health Sciences, Toyohashi SOZO University, Toyohashi, 440-8511, Japan.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Goto
keywords: Caveolin‐3; mechanical loading; skeletal muscle; tripartite motif‐containing 72