Mechanisms of plasma membrane repair and myokine secretion

Physiological factors such as gravity, food intake, daily physical activity, strenuous exercise, elevated blood pressure, excretory processes, and various stresses often induce transient disruption of cell membranes. Remarkably, cells have an inherent ability to rapidly repair such membrane disruptions. If the damage is minor, tissue regeneration, such as stem cell-mediated repair, is not necessary. Instead, tissue integrity is maintained through repeated membrane damage and repair. This rapid repair process is mediated primarily by calcium-dependent exocytosis, which not only promotes membrane resealing but also allows the release of intracellular signaling molecules. Skeletal muscle, which comprises approximately 40% of the human body, is a specialized group of cells for locomotor functions, and its long, large muscle fibers repeatedly undergo membrane damage during exercise. It has been revealed that cytokines are secreted at the moment of such membrane damage, and the contribution of exercise to muscle tissue homeostasis is now being elucidated at the molecular level. This finding has attracted attention in the field of space medicine, where muscle atrophy under microgravity conditions is a research target. Recently, a group of cytokines that are derived from skeletal muscle but have physiological effects on remote organs have been proposed as “myokines” and have become widely recognized in the field of exercise physiology and metabolism research. Many myokines are secreted during repair of sarcolemma damage, and their secretion is regulated by the subsequent membrane repair process. Here, we summarize the mechanism of cell membrane repair and myokine secretion. Membrane repair is an important cellular event in both health and disease.