J Appl Physiol 98: 1541, 2005;
doi:10.1152/japplphysiol.00058.2005
8750-7587/05 $8.00
COMMENTARY
HIGHLIGHTED TOPICS
Biomechanics and Mechanotransduction in Cells and Tissues
Commentary
Many studies have implicated caveolae and the scaffolding protein caveolin in the process of mechanotransduction. In the first featured article entitled "Reduction of caveolin-3 expression does not inhibit stretch-induced phosphorylation of ERK2 in skeletal muscle myotubes," Dr. A. Bellott and colleagues (1) suggest that stretch-induced changes in the shape of caveolae may disrupt caveolin-mediated inhibition of signaling molecules such as ERK2, PLA2, and nNOS to initiate mechanotransduction. To test the hypothesis that caveolin is directly involved in mechanotransduction, these investigators reduced caveolin-3 protein expression and evaluated ERK2 phosphorylation as a marker of stretch-induced signaling. The presence of ERK2 phosphorylation was consistent with the involvement of a viscous process, such as caveolae deformation, but ERK2 phosphorylation was not altered by a substantial reduction of caveolin protein. Although these results suggest that caveolae play a role in mechanotransduction, it does not appear that the inhibitory role of caveolin-3 is critical to the process. This work builds from an observable, nano-scale deformation to a putative molecular mechanism for mechanotransduction and highlights the potential importance of non-protein structures in initiating mechanotransduction.
The age-associated decline in muscle mass presents a significant problem with broad public health implications. Recent studies have suggested that, in response to a mechanical overload stimulus, muscle from older subjects does not hypertrophy to the same magnitude as muscle from younger subjects. In the second featured article, entitled "Aging does not alter the mechanosensitivity of the p38, p70S6k, and JNK2 signaling pathways in skeletal muscle," Dr. T. Hornberger and colleagues (2) focus on mechanotransduction in muscles and ask the question of whether mechanosensitivity varies with age. Specifically, they examine whether the intracellular molecular responses to defined mechanical strain in muscles from older mice were similar to those of younger animals. The results of this study indicate that mechanosensitivity is not altered with aging, implying that the impaired ability of skeletal muscle to grow in response to mechanical stimulation is not associated with deficits at the level of mechanotransduction.
Gary C. Sieck
Journal of Applied Physiology
April 2005, Volume 98
REFERENCES
- Bellot AC, Patel KC, and Burkholder TJ. Reduction of caveolin-3 expression does not inhibit stretch induced phosphorylation of ERK2 in skeletal muscle myotubes. J Appl Physiol 98: 1554–1561, 2005.[Abstract/Free Full Text]
- Hornberger TA, Mateja RD, Chin ER, Andrews JL, and Esser KA. Aging does not alter the mechanosensitivity of the p38, p70S6k, and JNK2 signaling pathways in skeletal muscle. J Appl Physiol 98: 1562–1566, 2005.[Abstract/Free Full Text]
Copyright © 2005 by the American Physiological Society.
