Scientists at the University of Tsukuba have identified the Maf transcription factor family’s vital role in the transition of muscle fibers from slow-twitch to fast-twitch. The researchers designed a triple knockout (TKO) mouse model to inactivate three Maf proteins (Mafa, Mafb, and Maf), resulting in a significant reduction in fast-twitch muscle mass in the mice, indicating the importance of Maf proteins in muscle development. The study found that large Mafs play a direct role in regulating Type 2b myofibers, supporting fast type IIb myofiber determination. The researchers noted that their data offers new insights into how slow-to-fast muscle fiber transition occurs in mammals and may support further research identifying novel therapeutic targets for muscular disorders.
Scientists at the University of Tsukuba have discovered the vital role of a protein family in regulating fast-twitch muscle fibers, which are involved in swift and powerful movements. The research published in Cell Reports highlights the significance of the Maf transcription factor family in the transition of muscle fibers from slow-twitch to fast-twitch. The human body’s musculature contains various myofibers that can be shaped by factors such as aging, spaceflight, exercise, and immobilization. These myofibers are categorized as slow-twitch or fast-twitch, with the latter further divided into three types based on the expression of myosin heavy chain proteins. Slow-twitch fibers are rich in mitochondria and suitable for endurance activities, while fast-twitch fibers are used for brief and powerful movements such as weightlifting. Though the factors responsible for slow-twitch fiber formation are well-known, less is understood about the transcription factors required for generating fast-twitch fibers. The Maf protein family’s newly identified role in this process sheds light on the critical role of this protein family in muscle development.
According to research by scientists at the University of Tsukuba published in Cell Reports, long durations of reduced activity, such as those experienced by astronauts in space, may encourage slow-to-fast muscle fiber transition. Previous research from the team had already demonstrated that Maf expression is affected by gravitational load variation. The researchers have now identified that a group of proteins, known as the large Maf transcription factor family, play a vital role in muscle development.
The team designed a triple knockout (TKO) mouse model, where three Maf proteins – Mafa, Mafb, and Maf – were inactivated, resulting in a significant reduction in fast-twitch muscle mass in the mice. However, there was no apparent impact on slow-twitch muscle mass. The TKO mice also lacked Type 2b fast-twitch fibers, which play a crucial role in brief and powerful movements.
The mice with inactivated Maf proteins had significantly lower average grip strength but could run longer on a treadmill than the control mice, indicating that more fast-to-slow muscle fiber conversion had occurred in the absence of large Maf expression. On the other hand, when the researchers overexpressed Mafs in the leg muscle of mice, there was a significant increase in Type 2b fibers.
The researchers note that the gene deletions occur at the embryonic phase of muscle development in their mouse model. However, their data could offer new insights into how slow-to-fast muscle fiber transition occurs in mammals and may support further research identifying novel therapeutic targets for muscular disorders.
The study also sheds light on the significance of the Maf protein family in the transition of muscle fibers from slow-twitch to fast-twitch. The researchers found that the expression of the large Maf transcription factor family responded dynamically to mechanical stimuli, indicating that these proteins are induced in muscles experiencing slow-to-fast muscle fiber transition. This could be a potential treatment target for muscular disorders.
Large Mafs play a vital role in directly regulating Type 2b myofibers during the development and adaptation of skeletal muscle, according to the research team. The team has identified large Mafs as robust transcriptional elements that contribute to fast type IIb myofiber determination. The study offers insights into the importance of Maf transcription factor family in regulating the transition of muscle fibers from slow-twitch to fast-twitch, and highlights the potential of these proteins as treatment targets for muscular disorders.
Don’t miss interesting posts on Famousbio
