The Mechanical Properties of Titin within a Sarcomere?

Authors

  • Jens A Herzog Faculty of Kinesiology, University of Calgary, Calgary AB, Canada
  • Tim R Leonard Faculty of Kinesiology, University of Calgary, Calgary AB, Canada
  • Azim Jinha Faculty of Kinesiology, University of Calgary, Calgary AB, Canada
  • Walter Herog Faculty of Kinesiology, University of Calgary, Calgary AB, Canada

Keywords:

skeletal muscle, passive force, titin, connectin, myofibril, sarcomere, mechanism of contraction, muscle injury, muscle stability, force-length relationship, muscle properties

Abstract

Titin is a structural protein in muscle that spans the half sarcomere from z-band to M-line. Although there are selected studies on titin’s mechanical properties from tests on isolated molecules or titin fragments, little is known about its behavior within the structural confines of a sarcomere. Here, we tested the hypothesis that titin properties might be reflected well in single myofibrils. Therefore, the purpose of this study was to measure the passive mechanical properties of isolated single myofibrils and evaluate whether these properties reflect the basic mechanical properties of the titin molecule. Single myofibrils from rabbit psoas were prepared for measurement of passive stretch-shortening cycles at lengths where passive titin forces become important. Three repeat stretch-shortening cycles with magnitudes between 1.0-3.0μm/sarcomere were performed at a speed of 0.1μm/s·sarcomere and repeated after a ten minute rest at zero force. These tests were performed in a relaxation solution (passive) and an activation solution (active) where cross-bridge attachment was inhibited with butanedione monoxime. Myofibrils behaved viscoelastically producing an increased efficiency with repeat stretch-shortening cycles, but a decreased efficiency with increasing stretch magnitudes. Furthermore, we observed a first distinct inflection point in the force-elongation curve at an average sarcomere length of 3.5μm that was associated with an average force of 68±5nN/mm-1. This inflection point was thought to reflect Ig domain unfolding and was missing after a ten minute rest at zero force, suggesting a lack of spontaneous Ig domain refolding. These passive myofibrillar properties are consistent with those observed in isolated titin molecules, suggesting that the mechanics of titin are well preserved in isolated myofibrils, and thus, can be studied readily in myofibrils, rather than in the extremely difficult and labile single titin preparations.

References

Astier, C., Raynaud, F., Lebart, M. C., Roustan, C., Benyamin, Y., (1998). Binding of a native titin fragment to actin is regulated by PIP2. FEBS Lett. 429, 95-98.

Bianco, P., Nagy, A., Kengyel, A., Szatmari, D., Martonfalvi, Z., Huber, T., Kellermayer, M. S. Z., (2007). Interaction forces between F-actin and titin PEVK domain measured with optical tweezers. Biophysical Journal 93, 2102-2109.

Cazorla, O., Vassort, G., Garnier, D., Le Guennec, J. Y., (1999). Length modulation of active force in rat cardiac myocytes: is titin the sensor? J Mol Cell Cardiol 31, 1215-1227.

Duvall, M., (2010). Does calcium interact with titin's immunoglobulin domain in cardiac muscle? Biophys J 98, 597a.

Fukuda, N., Wu, Y., Farman, G., Irving, T. C., Granzier, H. L. M., (2005). Titin-based modulation of active tension and interfilament lattice spacing in skinned rat cardiac muscle. Pflügers Arch - Eur J Physiol 449, 449-457.

Granzier, H. L. M., Irving, T. C., (1995). Passive tension in cardiac muscle: contribution of collagen, titin, microtubules, and intermediate filaments. Biophys J 68, 1027-1044.

Granzier, H. L. M., Kellermayer, M. S. Z., Helmes, M., Trombitás, K., (1997). Titin elasticity and mechanism of passive force development in rat cardiac myocytes probed by thin-filament extraction. Biophys J 73, 2043-2053.

Granzier, H. L. M., Labeit, S., (2007). Structure-function relations of the giant elastic protein titin in striated and smooth muscle cells. Muscle Nerve 36, 740-755.

Herzog, W., (1999). Muscle. In: Nigg, B. M., Herzog, W. (Eds.), Biomechanics of the Musculoskeletal System. John Wiley & Sons Ltd., Chichester, England, pp. 148-188.

Herzog, W., Joumaa, V., Leonard, T. R., (2010). On the mechanics of single sarcomeres. Molecular and Cellular Biomechanics 1, 25-31.

Herzog, W., Leonard, T. R., (2002). Force enhancement following stretching of skeletal muscle: a new mechanism. J Exp Biol 205, 1275-1283.

Hinkle, D. F., Wiersma, W., Jurs, S. G., (1979). Applied statistics for the behavioral sciences. Applied Statistics for the Behavioural Sciences. Rand McNally College Publishing Co, Chicago, pp. 332-367.

Horowits, R., Kempner, E. S., Bisher, M. E., Podolsky, R., (1986). A physiological role for titin and nebulin in skeletal muscle. Nature 323, 160-164.

Horowits, R., Podolsky, R. J., (1987). The positional stability of thick filaments in activated skeletal muscle depends on sarcomere length: evidence for the role of titin filaments. J Cell Biol 105, 2217-2223.

Joumaa, V., Rassier, D. E., Leonard, T. R., Herzog, W., (2007). Passive force enhancement in single myofibrils. Pflügers Arch - Eur J Physiol 455, 367-371.

Joumaa, V., Rassier, D. E., Leonard, T. R., Herzog, W., (2008). The origin of passive force enhancement in skeletal muscle. Am J Physiol Cell Physiol 294, C74-C78.

Kellermayer, M. S. Z., Smith, S. B., Granzier, H. L. M., Bustamante, C., (1997). Folding-unfolding transitions in single titin molecules characterized with laser tweezers. Science 276, 1112-1116.

Kulke, M., Fujita-Becker, S., Rostkova, E., Neagoe, C., Labeit, D., Manstein, D. J., Gautel, M., Linke, W. A., (2001). Interaction between PEVK-titin and actin filaments: origin of a vicous force component in cardiac myofibrils. Circ Res 89, 874-881.

Labeit, D., Watanabe, K., Witt, C., Fujita, H., Wu, Y., Lahmers, S., Funck, T., Labeit, S., Granzier, H. L. M., (2003). Calcium-dependent molecular spring elements in the giant protein titin. Proceedings of the National Academy of Sciences of the United States of America 100, 13716-13721.

Leonard, T. R., Duvall, M., Herzog, W., (2010a). Force enhancement following stretch in a single sarcomere. Am J Physiol Cell Physiol In Press.

Leonard, T. R., Herzog, W., (2010). Regulation of muscle force in the absence of actin-myosin based cross-bridge interaction. Am.J Physiol Cell Physiol 299, C14-C20.

Leonard, T. R., Joumaa, V., Herzog, W., (2010b). An activatable molecular spring reduces muscle tearing during extreme stretching. J Biomech. 43, 3063-3066.

Linke, W. A., Kulke, M., Li, H., Fujita-Becker, S., Neagoe, C., Manstein, D. J., Gautel, M., Fernandez, J. M., (2002). PEVK domain of titin: an entropic spring with actin-binding properties. Journal of Structural Biology 137, 194-205.

Maruyama, K., (1976). Connectin, an elastic protein from myofibrils. J Biochem. 80, 405-407.

Wang, K., Mcclure, J., Tu, A., (1979). Titin: major myofibrillar components of striated muscle. Proc Natl.Acad.Sci U.S.A 76, 3698-3702.

Williams, P. M., Fowler, S. B., Best, R. B., Toca-Herrera, J. L., Scott, K. A., Steward, A., Clarke, J., (2003). Hidden complexity in the mechanical properties of titin. Nature 422, 446-449.

Yamasaki, R., Berri, M., Wu, Y., Trombitas, K., McNabb, M., Kellermayer, M. S. Z., Witt, C., Labeit, D., Labeit, S., Greaser, M., Granzier, H. L. M., (2001). Titin-Actin interaction in mouse myocardium: passive tension modulation and its regulation by calcium/S100A1. Biophysical Journal 81, 2297-2313.

Downloads

Additional Files

Published

2012-11-26

Issue

Vol. 2 (2012)

Section

Articles

License

Authors retain all rights to their research work. Articles may be submitted to and accepted in other journals subsequent to publishing in JURA. Our only condition is that articles cannot be used in another undergraduate journal. Authors must be aware, however, that professional journals may refuse articles submitted or accepted elsewhere—JURA included.