myomerger

Myomerger is a small transmembrane protein that plays a key role in skeletal muscle development by mediating the fusion of myoblasts into multi-nucleated myotubes. Along with myomaker, myomerger is required for the membrane fusion stage of myogenesis, enabling fusion between adjacent muscle precursor cells during embryogenesis and in adult muscle regeneration.

Discovery and naming: Myomerger was identified in studies of myoblast fusion and is sometimes referred to by alternative names in early literature, such as Minion. It is described as a muscle-specific factor that works in concert with other fusion proteins to drive myoblast fusion.

Structure and expression: The protein is predicted to contain two transmembrane domains and localizes to the plasma membrane of differentiating myoblasts. Its expression is largely restricted to the skeletal muscle lineage, with higher levels during periods of active muscle formation and repair.

Function and mechanism: Myomerger cooperates with myomaker to promote membrane fusion. Loss of myomerger blocks muscle cell fusion without preventing myoblast differentiation, indicating a specific role in the fusion process rather than in early myogenic programs. In some experimental systems, co-expression of myomaker and myomerger can drive fusion in non-muscle contexts, highlighting their complementary roles in membrane remodeling and fusion.

Genetic and physiological relevance: Animal models lacking myomerger exhibit impaired myofiber formation and severe muscle defects, underscoring its essential role in proper muscle development and regeneration. These models help illuminate the distinct steps of myogenesis and the cellular mechanics of fusion.

Clinical and research implications: Understanding myomerger contributes to the broader knowledge of myogenesis and may inform strategies for muscle repair or therapies for muscle-wasting conditions. Related proteins involved in fusion include myomaker, which functions in a closely linked pathway.