Formerly known as Growth differentiation factor 8 (GDF 8), myostatin is a growth factor that limits muscle tissue. It is part of the Beta 1 HFR family.
It is a protein that has a direct action on growth by acting on muscle fibers. Myostatin is thus found in muscle cells.
If myostatin is too weak, the muscles will be overdeveloped. Otherwise, if myostatin is too high in the body, muscle mass will be insufficient. This is the case, for example, for people with heart failure: the heart contains too much myostatin.
This protein is present in the striated muscle cells of skeletal muscle.
People who are deficient in this protein have a totally hypertrophied muscular appearance, just like athletes who practice intensive bodybuilding.
In the case of excess myostatin in the body, the person, or the animal, will suffer from a real delay in muscle development.
Regular exercise can reduce the level of this protein in the body in a concrete way, both in the skeletal muscle and in the heart.
Several studies have been conducted on the functioning of the natural mechanism of regulation of muscle growth by the myostatin protein, wishing to find a way to block its action, in order to achieve an increase in muscle mass, whether in humans or animals.
The muscle hypertrophy caused by the myostatin disorder is due to the mutation of the GDF8 gene which is found in chromosome 2.
The increase in muscle size does not necessarily come with an increase in muscle strength , which should naturally accompany it. The fatty tissue that is related to the muscle is very generally thin.
Homozygous or heterozygous carriers have the same clinical signs, which depend solely on the amount of myostatin. Simply, homozygotes have muscles that are double normal in terms of volume.
Follistatin
Follistatins are proteins. Their actions are involved in the fine regulation of growth factors of the TGF beta family, acting mainly on activins and inhibitions.
Their roles are to inactivate growth factors that are members of the TG beta family. How does it work? Follistatins bind to growth factors, affecting the amount of these proteins that will successfully bind to their receptors.
Their main property is that they act in a way that is very close to their places of production. Follastin binds to the beta a and b subunits of these proteins, so logically two follastins are needed to inactivate an activin and one for one inhibin.
ACVR2B Peptides (ACE-031) 1mg
It is (ACE-31) an experimental therapeutic protein. Its role is to strengthen muscles and increase strength. Its intervention is the inhibition of molecules that bind through a cell surface receptor called activin type IIB Receptor (ActRIIB).
It is by joining part of a human antibody with a part of the human ActRIIB receptor that the ACE-031 protein is formed.
The free circulation of this ActRIIB protein eliminates other proteins of the GDF-8 genus and also other molecules of the same family that limit muscle growth and strength.
The TGF-8 beta protein family serves as a trigger for muscle production. It intervenes in the initiation or cessation of muscle growth.
In the absence of these molecules (which act by signaling thanks to the ActRIIB receptor), the increase in muscle mass is impressive. This phenomenon has been observed in many species, and more particularly in several animal species.
ACE-031 treats skeletal muscle and promotes muscle growth by inhibiting ActRIIB information that must bind to proteins to limit muscle growth.
When ACE-031 is bound with these proteins, the interaction with ActRIIB receptors is blocked and, as a result, the regulation of muscle growth does not take place. The muscle therefore continues to develop in a significant way.
Because ACE-031 prevents GDF-8 proteins (among others) from acting on the regulation of muscle mass by transmitting information to the ActRIIB receptor, its effects on lean muscle mass are far greater than those of GDF-8 inhibitors alone (myostatin).
Medical studies on Myostatin inhibitor
It was at the University of Baltimore that a protein synthesized in mammals (including humans) was discovered in 1997.
Its role is to block the proliferation of muscle cells, which allows the repair or control of this muscle growth.
The medical profession very quickly saw an interest in this product to help people undergoing treatment to fight muscle weakness or strength deficiency. Indeed, the inhibition of the activity of the molecule made it possible to envisage the proliferation of muscle cells.
Several methods of inhibiting myostatin activity have been developed. The aim of these methods is to prevent the binding between myostatin and its receptor (ACVR2b), which leads to the blocking of myostatin activity and thus an increase in muscle mass.
One method is to complex the myostatin with another molecule before it binds to its receptor. Several molecules can be used for this purpose. Some are endogenous molecules naturally present in humans and play a role in modulating myostatin activity. One of these molecules is follistatin. Present in human serum, this protein is a natural inhibitor of myostatin.
Another endogenous molecule that inhibits myostatin activity is myostatin propeptide.
This propeptide present in the structure of immature myostatin (latent myostatin) is cleaved during myostatin activation. Subsequently, it will return to bind to the active myostatin and then inhibit binding to its receptor. Synthetic peptides identical to these natural peptides are used by some athletes to inhibit the action of myostatin.
Other molecules, which are produced naturally by the human body, prevent the interaction between myostatin and its receptor. There are also anti-myostatin antibodies that will sequester and cause inhibition of its binding. Another product, consisting of a myostatin-binding site identical to that of the natural receptor coupled to a human antibody fragment, forms a soluble myostatin receptor unable to trigger the signal leading to the blocking of muscle cell proliferation. Part of the myostatin protein that can bind to myostatin receptors and block it without triggering the intracellular signals that cause muscle growth to stop has also been produced completely artificially in the research laboratory.
Use in doping
At the level of athletes, gene doping, i.e. the optimal physiological conditions, has several objectives. The increase in the size and power of the muscle is one of them, there is also the improvement of direct performance, and also, to allow a faster healing (in case of muscle injury) or a faster and optimal recovery in order to be able to resume training in higher doses quickly.
Biological doping therefore required “tackling” three main points: training more skeletal muscle, increasing the oxygen capacity in the body, and finally, increasing energy intake as much as possible.
This molecule is therefore of real interest to high-level athletes because it is naturally secreted by skeletal muscle cells during development and in adulthood. It is encoded by the gene of the same name located on chromosome 2.
It plays an important role in regulating muscle growth. Indeed, its intervention is real to signal the cessation of muscle tissue production, which consists of preventing excessive muscle growth.
The interest for gene doping would therefore be to inhibit myostatin. When taken intravenously, several methods are being studied to block (inhibit) the action of myostatin:
- Discontinue active myostatin with antibodies.
- Inactivate myostatin with a synthetic propeptide (not produced by the body).
- Increase the expression of natural myostatin inhibitors such as follistatin.
- Inactivate myostatin receptors attached to skeletal cells.
These inhibitors therefore make it possible to inactivate the muscle-regulating function of myostatin muscles. If this function is inactivated, the muscles can therefore grow disproportionately, which would favor the practice of sports requiring high muscle power such as weightlifting or body-building or all sports in which power and muscle mass are very important.
The majority of scientists are in complete agreement that myostatin inhibition in humans will be possible in the near future. As a result, all anti-doping organizations are already at work and preparing to find tests that can detect the blockage of the blocked myostatin.