title: Correlation between Ribosome Biogenesis and the Magnitude of Hypertrophy in Overloaded Skeletal Muscle.
abstract: External loads applied to skeletal muscle cause increases in the protein translation rate, which leads to muscle hypertrophy. Although some studies have demonstrated that increases in the capacity and efficiency of translation are involved in this process, it remains unclear how these two factors are related to the magnitude of muscle hypertrophy. The present study aimed to clarify the roles played by the capacity and efficiency of translation in muscle hypertrophy. We used an improved synergist ablation in which the magnitude of compensatory hypertrophy could be controlled by partial removal of synergist muscles. Male rats were assigned to four groups in which the plantaris muscle was unilaterally subjected to weak (WK), moderate (MO), middle (MI), and strong (ST) overloading by four types of synergist ablation. Fourteen days after surgery, the weight of the plantaris muscle per body weight increased by 8%, 22%, 32% and 45%, in the WK, MO, MI and ST groups, respectively. Five days after surgery, 18+28S rRNA content (an indicator of translational capacity) increased with increasing overload, with increases of 1.8-fold (MO), 2.2-fold (MI), and 2.5-fold (ST), respectively, relative to non-overloaded muscle (NL) in the WK group. rRNA content showed a strong correlation with relative muscle weight measured 14 days after surgery (r = 0.98). The phosphorylated form of p70S6K (a positive regulator of translational efficiency) showed a marked increase in the MO group, but no further increase was observed with further increase in overload (increases of 22.6-fold (MO), 17.4-fold (MI), and 18.2-fold (ST), respectively, relative to NL in the WK group). These results indicate that increases in ribosome biogenesis at the early phase of overloading are strongly dependent on the amount of overloading, and may play an important role in increasing the translational capacity for further gain of muscular size.
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakada
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Riki
authors.initials: R
authors.lastname: Ogasawara
authors.affiliation: Department of Sport and Medical Science, Teikyo University Faculty of Medical Technology, Tokyo, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Kawada
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Maekawa
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Naokata
authors.initials: N
authors.lastname: Ishii
mesh_terms: D000818:Animals; D006984:Hypertrophy / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology / Q000601:surgery; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000503:physiopathology / Q000601:surgery; D001678:Organelle Biogenesis; D010766:Phosphorylation; D014176:Protein Biosynthesis; D012337:RNA, Ribosomal, 18S / Q000096:biosynthesis / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000096:biosynthesis* / Q000235:genetics; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*
chemical_list: D009124:Muscle Proteins; D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S; D038762:Ribosomal Protein S6 Kinases, 70-kDa
references.citation: EMBO J. 2006 Apr 5;25(7):1522-33
references.pmid: 16541106
references.citation: Physiol Behav. 1995 May;57(5):913-9
references.pmid: 7610144
references.citation: J Physiol. 2011 Apr 1;589(Pt 7):1831-46
references.pmid: 21300751
references.citation: J Cell Biol. 1968 Mar;36(3):653-8
references.pmid: 5645554
references.citation: Eur J Biochem. 1972 Sep 25;29(3):585-92
references.pmid: 5083511
references.citation: Clin Orthop Relat Res. 2002 Oct;(403 Suppl):S178-87
references.pmid: 12394467
references.citation: J Appl Physiol (1985). 2012 Jul;113(1):71-7
references.pmid: 22518835
references.citation: J Biol Chem. 1996 Feb 9;271(6):3213-20
references.pmid: 8621723
references.citation: Curr Biol. 2007 Jun 5;17(11):R415-7
references.pmid: 17550767
references.citation: Eur J Appl Physiol. 2008 Jan;102(2):145-52
references.pmid: 17874120
references.citation: Curr Opin Pharmacol. 2012 Jun;12(3):377-82
references.pmid: 22445545
references.citation: J Appl Physiol (1985). 2013 Apr;114(7):934-40
references.pmid: 23372143
references.citation: Appl Physiol Nutr Metab. 2009 Jun;34(3):403-10
references.pmid: 19448706
references.citation: J Physiol. 2010 Aug 15;588(Pt 16):3119-30
references.pmid: 20581041
references.citation: J Proteome Res. 2011 Mar 4;10(3):1416-9
references.pmid: 21186791
references.citation: J Appl Physiol (1985). 2014 Mar 15;116(6):693-702
references.pmid: 24458751
references.citation: J Mol Cell Cardiol. 2013 Jun;59:139-47
references.pmid: 23510923
references.citation: J Appl Physiol (1985). 2013 Oct 1;115(7):1065-74
references.pmid: 23869057
references.citation: J Appl Physiol (1985). 1999 Aug;87(2):634-42
references.pmid: 10444623
references.citation: J Cell Physiol. 2012 Apr;227(4):1569-76
references.pmid: 21678406
references.citation: Am J Physiol Cell Physiol. 2002 Oct;283(4):C1182-95
references.pmid: 12225982
references.citation: J Physiol. 2011 Jun 15;589(Pt 12):3023-37
references.pmid: 21486778
references.citation: Trends Biochem Sci. 1999 Nov;24(11):437-40
references.pmid: 10542411
references.citation: Eur J Biochem. 1972 Jan 31;25(1):117-28
references.pmid: 5023577
references.citation: J Cell Physiol. 2014 Nov;229(11):1584-94
references.pmid: 24604615
references.citation: Am J Physiol. 1999 Jan;276(1 Pt 1):C120-7
references.pmid: 9886927
references.citation: PLoS One. 2013;8(10):e78636
references.pmid: 24130904
references.citation: Am J Physiol Cell Physiol. 2005 Dec;289(6):C1457-65
references.pmid: 16079186
references.citation: Am J Physiol Regul Integr Comp Physiol. 2012 Mar 1;302(5):R643-54
references.pmid: 22189670
references.citation: Ann Anat. 2011 Feb 20;193(1):56-63
references.pmid: 20833519
references.citation: J Physiol. 2011 Nov 15;589(Pt 22):5485-501
references.pmid: 21946849
references.citation: Am J Physiol Endocrinol Metab. 2015 Jul 1;309(1):E72-83
references.pmid: 25968575
references.citation: PLoS One. 2010;5(2):e8994
references.pmid: 20126553
references.citation: Am J Physiol Cell Physiol. 2012 May 15;302(10):C1523-30
references.pmid: 22403788
references.citation: J Sports Sci Med. 2010 Jun 01;9(2):170-5
references.pmid: 24149682
references.citation: J Biol Chem. 2013 Jan 11;288(2):1125-34
references.pmid: 23209294