In this project we used two genetically modified animal models. One of them had a transgene that overexpressed the myostatin (Mst) protein under the regulation of muscle specific creatine kinase (MCK) promoter. These animals were called transgenic mice (Tg). The other group of animals did not have the functional Mst protein, and were called Mst knock-out (KO) mice. As control, we used wild type (WT) mice (C57Bl/6) for all of our studies.

Myostatin is a member of transforming growth factor-beta (TGF-β) superfamily, and is considered as negative regulator of skeletal muscle growth and differentiation during embryogenesis. The function of this protein in adult skeletal muscle tissues is not elucidated to date.

Our goal is to characterize and identify the changes in muscle structure and fiber composition followed by functional tests on the three animal groups (Tg, KO, WT).

Methods: Skeletal muscle samples were collected, formaldehyde-fixed and sectioned. The tissue sections will be stained immunohistochemically with monoclonal anibodies for fast and slow type fibers and developed by ABC/VIP kit (Vector Laboratories, Inc.).
Utilizing this method, we will be able to detect the changes in fiber type composition and correlate these changes to the muscle functional/physiological changes caused by myostatin in adult mice.