SH3KBP1 promotes skeletal myofiber formation and functionality through ER/SR architecture integrity

Area of Science:

• Muscle biology
• Cellular dynamics
• Molecular mechanisms

Background:

• Myonuclei arrangement and sarcoplasmic reticulum organization are crucial for muscle formation and function.
• Identifying factors that maintain muscle integrity is essential for understanding muscle diseases.

Purpose of the Study:

• To identify novel factors involved in maintaining muscle integrity.
• To elucidate the role of SH3KBP1 in myogenesis and muscle function.

Main Methods:

• Performed an siRNA screen to identify factors controlling myoblast fusion, myonuclear positioning, and myotube elongation.
• Investigated the interaction domains of SH3KBP1 with dynamin-2 and calnexin.
• Assessed the impact of SH3KBP1 depletion in a mouse model of centronuclear myopathy (CNM).

Main Results:

• Identified SH3KBP1 as a novel regulator of myoblast fusion, myonuclear positioning, and myotube elongation.
• Demonstrated that SH3KBP1 interacts with dynamin-2 and calnexin, influencing myonuclei dynamics and ER integrity.
• Showed that SH3KBP1 is involved in triad formation and modulates excitation-contraction coupling efficiency.
• Found that SH3KBP1 depletion exacerbates atrophic phenotypes and impairs autophagic flux in a CNM mouse model.

Conclusions:

• SH3KBP1 is a critical regulator of myofiber integrity and muscle function.
• SH3KBP1 plays a significant role in myogenesis and maintaining muscle health.
• Targeting SH3KBP1 may offer therapeutic potential for muscle disorders like CNM.