skeletal muscle cell differentiation

Definition

Target type: biologicalprocess

The process in which a relatively unspecialized cell acquires specialized features of a skeletal muscle cell, a somatic cell located in skeletal muscle. [CL:0000188, GOC:BHF, GOC:vk]

Skeletal muscle cell differentiation is a complex and tightly regulated process that involves a series of coordinated events that transform undifferentiated precursor cells called satellite cells into mature, multinucleated muscle fibers. This process is essential for the development and regeneration of skeletal muscle, which is responsible for movement, posture, and thermogenesis.

**1. Commitment and Activation:**
Satellite cells, quiescent stem cells located beneath the basal lamina of muscle fibers, are activated in response to stimuli such as injury, exercise, or growth factors. This activation involves a series of signaling pathways that promote cell cycle entry and proliferation.

**2. Proliferation and Expansion:**
Activated satellite cells undergo a period of rapid proliferation, increasing their number to provide a pool of progenitors for differentiation. This proliferation is driven by growth factors like fibroblast growth factor (FGF) and insulin-like growth factor (IGF).

**3. Myoblast Fusion:**
The proliferating satellite cells differentiate into myoblasts, which are committed precursor cells that express muscle-specific proteins. Myoblasts align themselves along the muscle fiber axis and undergo a process called fusion, where multiple myoblasts fuse together to form multinucleated myotubes.

**4. Myotube Maturation and Differentiation:**
Myotubes undergo a series of structural and biochemical changes as they mature into functional muscle fibers. These changes include:

- **Myofibril Formation:** Myotubes assemble myofibrils, the contractile units of muscle fibers, composed of sarcomeres.
- **Sarcomere Assembly:** Sarcomeres, the fundamental building blocks of muscle, are assembled with specific arrangements of actin and myosin filaments.
- **Expression of Muscle-Specific Proteins:** The expression of muscle-specific proteins, such as myosin heavy chains, troponin, and tropomyosin, increases dramatically.
- **Development of the Sarcoplasmic Reticulum:** The sarcoplasmic reticulum, an intracellular membrane network responsible for calcium regulation, develops and expands.

**5. Maturation and Regeneration:**
Once myotubes have matured into functional muscle fibers, they can participate in muscle growth and regeneration. During regeneration, satellite cells are activated to replace damaged muscle fibers, ensuring tissue repair and functional integrity.

Throughout this process, a complex interplay of signaling pathways, transcription factors, and regulatory molecules orchestrates the fate of satellite cells and their differentiation into mature muscle fibers. These factors include:

- **Myogenic Regulatory Factors (MRFs):** MyoD, Myf5, Myogenin, and MRF4 play crucial roles in muscle development and differentiation.
- **Growth Factors:** FGF, IGF, and others influence satellite cell activation and proliferation.
- **Cytokines:** Interleukins and other cytokines can influence the differentiation process.
- **Extracellular Matrix:** The surrounding extracellular matrix provides structural support and signaling cues for muscle development.

Understanding the intricate mechanisms of skeletal muscle cell differentiation is crucial for developing therapeutic strategies for muscle diseases and enhancing muscle function in healthy individuals.'
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Proteins (8)

Compounds (98)