Researchers from the German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) and other partner institutions of the German Center for Diabetes Research (DZD) have now identified a previously unknown function of the PICALM protein in skeletal muscle: The protein responds sensitively to physical activity and intermittent fasting. It also plays a decisive role in the formation of new muscle fibers. The team’s report has been published in the journal Molecular Metabolism .
Previous work at DIfE has already shown that the phosphatidylinositol binding clathrin assembly protein (PICALM) in adipose tissue is regulated by lifestyle interventions and influences metabolic processes there. The researchers have now combined various experimental approaches to investigate the role of PICALM in muscle. In studies using mouse models, including the established NZO model for metabolic disorders, they analyzed various forms of intermittent fasting. This revealed increased PICALM expression in muscle tissue. A similar effect was also observed in healthy mice that were subjected to regular exercise.
The team also analyzed muscle samples from a training study at the University of Tübingen, in which overweight participants completed a structured bicycle ergometer program. Here, too, PICALM expression increased after training. “The results indicate that PICALM plays an important role in how muscle cells adapt to changing living conditions,” says PD Dr. Heike Vogel from DIfE, last author of the publication.
Key Role in Muscle Formation
In experiments with cultured muscle cells, the researchers demonstrated that PICALM is essential for the formation of new muscle fibers from progenitor cells (myogenesis). If PICALM expression was reduced, these cells developed significantly less well into mature muscle fibers.
This is apparently due to disturbances in fundamental cellular processes. PICALM is involved in a mechanism by which cells take up and transport components such as epidermal growth factor (EGF). Impairments to this process, which is known as clathrin-mediated endocytosis, result in defects similar to those caused by a lack of PICALM.
A low PICALM level also changes the composition of proteins on the cell surface and disrupts the organization of the actin cytoskeleton. This network is crucial for cell shape, stability and movement—and therefore also for the alignment and fusion of muscle progenitor cells into functioning muscle fibers.
New Perspectives for Prevention and Therapy
“We have discovered that PICALM is an important component of the molecular adaptation mechanisms in muscle. It responds to training and fasting, while also influencing the formation of new muscle fibers. In the long term, our findings could help to develop new approaches for the prevention and treatment of muscle loss in old age and metabolic diseases,” summarizes Vogel.
The study expands the understanding of the diverse functions of PICALM. While the protein primarily regulates metabolic processes in adipose tissue, it controls structural processes of cell formation in muscle. PICALM therefore takes on different functions depending on the tissue type.
Molecular Metabolism
Observational study
People
Picalm coordinates clathrin-mediated endocytosis and actin remodeling during myogenesis
7-Apr-2026