title: Sumoylated α-skeletal muscle actin in the skeletal muscle of adult rats.
abstract: Skeletal muscles are composed of two major muscle fiber types: slow-twitch oxidative fibers and fast-twitch glycolytic fibers. The proteins in these muscle fibers are known to differ in their expression, relative abundance, and post-translational modifications. In this study, we report a previously unreported post-translational modification of α-skeletal muscle actin in the skeletal muscles of adult male F344 rats in vivo. Using two-dimensional electrophoresis (2D-PAGE), we first examined the differences in the protein expression profiles between the soleus and plantaris muscles. We found higher intensity protein spots at approximately 60 kDa and pH 9 on 2D-PAGE for the soleus muscle compared with the plantaris muscle. These spots were identified as α-skeletal muscle actin by liquid chromatography-nanoelectrospray ionization-tandem mass spectrometry and western blot analyses. In addition, we found that the 60 kDa α-skeletal muscle actin is modified by small ubiquitin-like modifier (SUMO) 1, using 2D-PAGE and western blot analyses. Furthermore, we found that α-skeletal muscle actin with larger molecular weight was localized in the nuclear and cytosol of the skeletal muscle, but not in the myofibrillar fraction by the combination of subcellular fractionation and western blot analyses. These results suggest that α-skeletal muscle actin is modified by SUMO-1 in the skeletal muscles, localized in nuclear and cytosolic fractions, and the extent of this modification is much higher in the slow muscles than in the fast muscles. This is the first study to show the presence of SUMOylated actin in animal tissues.
authors.affiliation: Sportology Center, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Japan.|Faculty of Nursing, Hirosaki Gakuin University, Hirosaki, Aomori, Japan.
authors.forename: Munehiro
authors.initials: M
authors.lastname: Uda
authors.affiliation: The Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Inzai, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kawasaki
authors.affiliation: The Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Inzai, Japan.
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Iizumi
authors.affiliation: Institute of Health and Sports Science & Medicine, Juntendo University Graduate School of Health and Sports Science, Inzai, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Shigenaga
authors.affiliation: Juntendo University School of Medicine, Inzai, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Baba
authors.affiliation: Institute of Health and Sports Science & Medicine, Juntendo University Graduate School of Health and Sports Science, Inzai, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Naito
authors.affiliation: Faculty of Social Welfare, Hirosaki Gakuin University, Hirosaki, Japan.
authors.forename: Toshitada
authors.initials: T
authors.lastname: Yoshioka
authors.affiliation: Department of Chemistry, Juntendo University School of Health Care and Nursing, Inzai, Japan. hyamaku@juntendo.ac.jp.
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Yamakura
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D025842:SUMO-1 Protein / Q000378:metabolism*; D058207:Sumoylation / Q000502:physiology*
chemical_list: D000199:Actins; D025842:SUMO-1 Protein; C498862:Acta2 protein, rat
keywords: Fiber-type composition; Nuclear actin; SUMOylation; Skeletal muscles