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Myostatin means “stoppage of muscle growth.” Myostatin negatively regulates muscle growth and size of the muscular fiber during myogenesis (the formation of muscular tissue). It is the most important catabolic limiting factor of extreme muscular growth.
Scientists at the Johns Hopkins University isolated the protein in 1997. The earliest studies on animals born without the genes that code for myostatin production clearly showed that muscle growth is regulated by myostatin. Extensive muscle hypertrophy was noticed in the animals.
Growth Differentiation Factor-8 (GDF-8)
Myostatin, also called Growth Differentiation Factor-8 (GDF-8), is a protein that belongs to the family of secreted growth factors, TGF-β. Muscle cells are found to be extremely sensitive to this amino acid sequence. Several growth factors in this group mediate growth and differentiation during embryonic development. They also play a role in regeneration of muscle tissue in adults. Myostatin is unique among the family of growth factors in its expression in that it is restricted to skeletal muscle lineage. Myostatin is a protein encoded into the MSTN gene and people with mutations to the MSTN gene show significantly high levels of muscular mass and strength.
Myostatin is produced in skeletal muscle cells, and circulates throughout the body, binding to muscle tissue. Inhibition of myostatin results in significantly larger muscle mass. During a workout, muscle cells are broken down and buildup must begin immediately to repair and grow the muscle cells. This process is affected by myostatin, which determines how large a muscle will grow. A significant increase of myostatin level in the blood will inhibit buildup of muscle mass, no matter how much one trains or exercises. Similarly, a significant decrease in the myostatin levels in the blood boosts muscle growth.
Role of myostatin in obesity
Myostatin can effect body metabolism due to its influence on skeletal muscle growth and active lean tissue, which in turn may subsequently play a role in the development of obesity and diabetes. Myostatin minimally effects metabolic activity of other tissues such as adipose tissue in the presence of optimal nutrition and produce only a slight contribution to the changes occurring in obesity.
Myostatin as a therapeutic agent
Myostatin inhibitors may act as therapeutic agents for sarcopenia, or age-related muscular dystrophy in elderly people who are prone to injury that reduces their ability to lead a normal life. The aged population may benefit from increased muscle strength as myostatin levels have shown to decrease with age. In cachectic cancer patients who experience muscle wasting, increased muscle strength may improve quality of life, improve response to cancer treatment, and increase life span. Muscular dystrophies such as Duchenne’s muscular dystrophy may receive therapeutic benefit from increased skeletal muscle. Pharmacological inhibitors of myostatin may give therapeutic benefit to such debilitating muscular diseases.