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Journal of Biomedicine and Biotechnology
Volume 2010 (2010), Article ID 163203, 8 pages
http://dx.doi.org/10.1155/2010/163203
Research Article

The Masticatory Contractile Load Induced Expression and Activation of Akt1/PKB in Muscle Fibers at the Myotendinous Junction within Muscle-Tendon-Bone Unit

1Department of Operative Dentistry, Periodontics and Endodontics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
2Department I of Anatomy, University of Cologne, 50931 Cologne, Germany
3Department of Molecular and Cellular Sports Medicine, German Sports University, 50933 Cologne, Germany

Received 2 November 2009; Accepted 4 March 2010

Academic Editor: Guy M. Benian

Copyright © 2010 Yüksel Korkmaz et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The cell specific detection of enzyme activation in response to the physiological contractile load within muscle-tendon-bone unit is essential for understanding of the mechanical forces transmission from muscle cells via tendon to the bone. The hypothesis that the physiological mechanical loading regulates activation of Akt1/PKB at Thr308 and at Ser473 in muscle fibers within muscle-tendon-bone unit was tested using quantitative immunohistochemistry, confocal double fluorescence analysis, and immunoblot analysis. In comparison to the staining intensities in peripheral regions of the muscle fibers, Akt1/PKB was detected with a higher staining intensity in muscle fibers at the myotendinous junction (MTJ) areas. In muscle fibers at the MTJ areas, Akt1/PKB is dually phosphorylated at Thr308 and Ser473. The immunohistochemical results were confirmed by immunoblot analysis. We conclude that contractile load generated by masticatory muscles induces local domain-dependent expression of Akt1/PKB as well as activation by dually phosphorylation at Thr308 and Ser473 in muscle fibers at the MTJ areas within muscle-tendon-bone unit.