skeletal muscle fiber differentiation

Definition

Target type: biologicalprocess

The process in which a relatively unspecialized cell acquires specialized features of a skeletal muscle fiber cell. Skeletal muscle fiber differentiation starts with myoblast fusion and the appearance of specific cell markers (this is the cell development step). Then individual skeletal muscle fibers fuse to form bigger myotubes and start to contract. [GOC:dos]

Skeletal muscle fiber differentiation is a complex and tightly regulated process that involves the commitment of precursor cells, known as myoblasts, to differentiate into mature, multinucleated muscle fibers. This process is essential for the development and maintenance of skeletal muscle, which is responsible for movement, posture, and respiration.

The process begins with the activation of myoblasts, which are quiescent cells located in the muscle tissue. Growth factors, such as fibroblast growth factor (FGF) and insulin-like growth factor (IGF), trigger the myoblasts to exit the cell cycle and enter the differentiation pathway.

Once activated, myoblasts undergo a series of morphological and molecular changes, including:

* **Increased expression of myogenic regulatory factors (MRFs):** MRFs are a family of transcription factors that play a critical role in muscle development. These include MyoD, Myf5, Myogenin, and MRF4. These factors bind to specific DNA sequences in the promoters of muscle-specific genes, activating their expression.
* **Cell fusion:** Myoblasts fuse together to form multinucleated myotubes, which are the precursors to mature muscle fibers. This fusion process is mediated by cell adhesion molecules and cytoskeletal proteins.
* **Synthesis of muscle-specific proteins:** Myotubes begin to synthesize and assemble the contractile proteins actin and myosin, which are the building blocks of muscle fibers.
* **Formation of sarcomeres:** The contractile units of muscle fibers, called sarcomeres, are assembled from actin and myosin filaments. Sarcomeres are arranged in a highly organized manner, giving muscle fibers their characteristic striated appearance.
* **Maturation and specialization:** Myotubes mature into functional muscle fibers, developing specialized structures such as the sarcolemma (muscle cell membrane), transverse tubules (T-tubules), and sarcoplasmic reticulum (SR).

Throughout this process, several signaling pathways are involved, including the Wnt, Hedgehog, and Notch pathways, which regulate cell proliferation, differentiation, and survival.

Skeletal muscle fiber differentiation is a dynamic process that continues throughout life, allowing for muscle growth, repair, and regeneration. It is also influenced by external factors, such as exercise, nutrition, and aging. Understanding the molecular mechanisms underlying this process is crucial for developing therapies for muscle disorders and promoting muscle health.'
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Proteins (2)

Compounds (8)