AJP - Cell Physiology, Vol 267, Issue 1 C115-C126, Copyright © 1994 by American Physiological Society

ARTICLES

Soleus muscle nascent polypeptide chain elongation slows protein synthesis rate during non-weight-bearing activity

Z. Ku and D. B. Thomason
Department of Physiology and Biophysics, University of Tennessee College of Medicine, Memphis 38163.

Protein synthesis rate of the soleus muscle decreases rapidly during non-weight-bearing activity. We isolated polysomes from 18-h non-weight-bearing soleus muscle to investigate the mechanism of this phenomenon. The distribution of polysomal alpha-actin mRNA and 18S rRNA on sucrose density gradients shows that polysomes shift to larger sizes (more ribosomes per mRNA) during non-weight-bearing activity. Furthermore, RNA is mobilized into the polysome pool of the non-weight-bearing soleus muscle; these data indicate that initiation of protein synthesis is not rate limiting. We explain these results as the slowing of nascent polypeptide chain elongation, such that there is a "traffic jam" of ribosomes on the mRNAs, increasing the number of ribosomes per mRNA while, at the same time, decreasing protein synthesis rate. In support of this hypothesis, myoblasts treated with a low dose of cycloheximide (a specific elongation inhibitor) show a similar shift in polysome size. A numerical model of protein synthesis further shows that elongation is more effective than initiation and termination in affecting protein synthesis and polysome size. We conclude that the non-weight-bearing-induced decrease in postural muscle protein synthesis rate is initially caused by slowing of nascent polypeptide chain elongation.

This article has been cited by other articles:

				J. M. McClung, M. A. Whidden, A. N. Kavazis, D. J. Falk, K. C. DeRuisseau, and S. K. Powers Redox regulation of diaphragm proteolysis during mechanical ventilation Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2008; 294(5): R1608 - R1617. [Abstract] [Full Text] [PDF]

				J. M. McClung, R. W. Thompson, L. L. Lowe, and J. A. Carson RhoA expression during recovery from skeletal muscle disuse J Appl Physiol, April 1, 2004; 96(4): 1341 - 1348. [Abstract] [Full Text] [PDF]

				L. Bey, N. Akunuri, P. Zhao, E. P. Hoffman, D. G. Hamilton, and M. T. Hamilton Patterns of global gene expression in rat skeletal muscle during unloading and low-intensity ambulatory activity Physiol Genomics, April 16, 2003; 13(2): 157 - 167. [Abstract] [Full Text] [PDF]

				Y. Oishi, K. Taniguchi, H. Matsumoto, A. Ishihara, Y. Ohira, and R. R. Roy Muscle type-specific response of HSP60, HSP72, and HSC73 during recovery after elevation of muscle temperature J Appl Physiol, March 1, 2002; 92(3): 1097 - 1103. [Abstract] [Full Text] [PDF]

				T. A. Hornberger, R. B. Hunter, S. C. Kandarian, and K. A. Esser Regulation of translation factors during hindlimb unloading and denervation of skeletal muscle in rats Am J Physiol Cell Physiol, July 1, 2001; 281(1): C179 - C187. [Abstract] [Full Text] [PDF]

				R. H. Fitts, D. R. Riley, and J. J. Widrick Physiology of a Microgravity Environment Invited Review: Microgravity and skeletal muscle J Appl Physiol, August 1, 2000; 89(2): 823 - 839. [Abstract] [Full Text] [PDF]

				W. W. Ashley Jr. and B. Russell Tenotomy decreases reporter protein synthesis via the 3'-untranslated region of the beta -myosin heavy chain mRNA Am J Physiol Cell Physiol, July 1, 2000; 279(1): C257 - C265. [Abstract] [Full Text] [PDF]

				T. Y. Kostrominova, P. C. D. Macpherson, B. M. Carlson, and D. Goldman Regulation of myogenin protein expression in denervated muscles from young and old rats Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2000; 279(1): R179 - R188. [Abstract] [Full Text] [PDF]

				H. Naito, S. K. Powers, H. A. Demirel, T. Sugiura, S. L. Dodd, and J. Aoki Heat stress attenuates skeletal muscle atrophy in hindlimb-unweighted rats J Appl Physiol, January 1, 2000; 88(1): 359 - 363. [Abstract] [Full Text] [PDF]

				X.-Y. Han, W. Wang, R. Myllyla, P. Virtanen, J. Karpakka, and T. E. S. Takala mRNA levels for alpha -subunit of prolyl 4-hydroxylase and fibrillar collagens in immobilized rat skeletal muscle J Appl Physiol, July 1, 1999; 87(1): 90 - 96. [Abstract] [Full Text] [PDF]

				H. VANDENBURGH, J. CHROMIAK, J. SHANSKY, MICHAEL DEL TATTO, and J. LEMAIRE Space travel directly induces skeletal muscle atrophy FASEB J, June 1, 1999; 13(9): 1031 - 1038. [Abstract] [Full Text]

				T. P. Stein, M. D. Schluter, and L. L. Moldawer Endocrine relationships during human spaceflight Am J Physiol Endocrinol Metab, January 1, 1999; 276(1): E155 - E162. [Abstract] [Full Text] [PDF]