What causes muscle growth?
Three special proteins that have a major effect on muscle growth. Two of these proteins are produced by the body in varying amounts. These rhythmic fluctuations in gene expression are essential for the controlled transformation of stem cells into muscle cells.
The fluctuations in protein production greatly affect whether or not the body builds muscle, according to the results of a study involving researchers from the Max Delbrück Center for Molecular Medicine at the Helmholtz Association (MDC) in Berlin. The study was published in the Journal of the English Language.Nature Communications“Was released.
How does muscle growth work?
When people keep growing or start exercising regularly to build muscle, the muscles will get bigger. This is because some of the stem cells in that muscle develop into new muscle cells. The same process also occurs when the affected muscle begins to heal, the researchers explain.
Muscle stem cells need to produce new stem cells
At the same time, the team adds, muscle stem cells have to produce new stem cells, otherwise the supply of muscle stem cells will be depleted very quickly. However, this process assumes that the cells involved in muscle growth are communicating with each other.
What role do Hes1 and MyoD play?
Two years ago, a research group led by Professor Carmen Birchmeier of the Max Delbrück Center for Molecular Medicine in Berlin at the Helmholtz Association demonstrated that the evolution of stem cells into muscle cells is controlled with the support of the proteins Hes1 and MyoD, which are used in progenitor cells sometimes being produced in larger quantities. And sometimes in smaller quantities.
Both proteins share what’s called the Notch signaling pathway, which is a special mechanism by which cells interact with external stimuli and communicate with each other. And experts add that there is also a third protein that plays an important role.
“In our current study, we have now presented clear evidence that oscillation in muscle tissue is not just a peculiar phenomenon in the cells in question, but these rhythmic fluctuations in gene expression are really necessary to transform muscle-controlled stem cells into one” cells and just happen. In a limited range Press release.
The international research group was also able to identify a third important protein role. Together with the Hes1 and MyoD proteins, this forms a dynamic network in cells – Notch ligand Delta-like1 (Dll1 for short), the experts report.
Dll1 is periodically produced flux
Professor Birchmeier explains that Dll1 “is produced in activated muscle stem cells, which oscillate periodically with an oscillation time of two to three hours”. Every time a portion of the stem cells increasingly expresses Dll1, the amount present in the other cells is reduced accordingly. The expert adds: “These rhythmic signals determine whether the stem cell forms a new stem cell or develops into a muscle cell.”
The Hes1 protein determines the frequency of stem cells
The research group also investigated how the proteins Hes1 and MyoD are involved in muscle growth. This was done with the help of experiments on isolated stem cells, individual muscle fibers and mice. “In simple terms, it can be said that Hes1 acts as a pacemaker for oscillation, while MyoD increases Dll1 expression,” explains study author Dr. Inas Lehmann.
Mathematical models confirm the results
“Our experimental analyzes not only showed both, but also the mathematical models demonstrated by Professor Jana Woolf and Dr. Katharina Bohm at MDC,” adds Professor Birchmeier. Using transgenic mice, the research group produced the most important evidence that the Dll1 oscillation is really important for the controlled transformation of stem cells into muscle cells.
“A specific mutation in the Dll1 gene causes these animals to produce the protein with a time delay of a few minutes. This disrupts the oscillatory production of Dll1 in cell groups, but it does not change the total amount of the linker,” says Prof Birchmeier.
The effects of the mutation on stem cells
“However, the mutation has dangerous effects on stem cells, which transform prematurely into muscle cells and fibers,” explains study author Yao Zhang. Therefore, stem cells are used very quickly, which means that the muscle injuries of the hind legs of the mice did not heal sufficiently and these muscles generally remained smaller than they were before the injury. “It is clear that this minimal gene change is capable of disrupting successful communication – in the form of a fluctuation – between stem cells,” the expert adds.
Balance is the key
Birchmeier concludes that “only when Dll1 binds to the Notch receptor in an oscillatory fashion and thus periodically adjusts the signaling chain in stem cells in motion, is there clearly a good balance between self-renewal and cellular differentiation”.
Improving the treatment of muscle injuries in the future?
Researchers hope that an improved understanding of muscle regeneration and muscle growth in the future will help treat muscle injuries and muscle diseases more effectively than previously. (Like)
Author and source information
This text complies with the requirements of the specialized medical literature, medical guidelines and current studies and has been examined by medical professionals.
- Yao Zhang, Ines Laman, Katharina Baum, Hiromi Shimogo, Philippus Morikis et al .: Delta-like1 oscillations regulate the balance between differentiation and maintenance of muscle stem cells, in Nature Communications (veröffentlicht 26.02.2021), Nature Communications
- Max Delbrück Center for Molecular Medicine: What makes muscles grow properly (Posted on 02/26/2021), MDC
This article is for general guidance only and should not be used for self-diagnosis or self-medication. He cannot replace a visit to the doctor.