Phosphoproteomics of Acute Cell Stressors Targeting Exercise Signaling Networks Reveal Drug Interactions Regulating Protein Secretion

Summary: Exercise engages signaling networks to control the release of circulating factors beneficial to health. However, the nature of these networks remains undefined. Using high-throughput phosphoproteomics, we quantify 20,249 phosphorylation sites in skeletal muscle-like myotube cells and monitor their responses to a panel of cell stressors targeting aspects of exercise signaling in vivo. Integrating these in-depth phosphoproteomes with the phosphoproteome of acute aerobic exercise in human skeletal muscle suggests that co-administration of β-adrenergic and calcium agonists would activate complementary signaling relevant to this exercise context. The phosphoproteome of cells treated with this combination reveals a surprising divergence in signaling from the individual treatments. Remarkably, only the combination treatment promotes multisite phosphorylation of SERBP1, a regulator of Serpine1 mRNA stability, a pro-fibrotic secreted protein. Secretome analysis reveals that the combined treatments decrease secretion of SERPINE1 and other deleterious factors. This study provides a framework for dissecting phosphorylation-based signaling relevant to acute exercise. : Needham et al. measure phosphoproteomes of acute cell stressors targeting different aspects of exercise signaling. This reveals treatment actions and creates a resource of treatments that regulate phosphosites regulated in acute aerobic exercise in human skeletal muscle. Combining isoproterenol and thapsigargin causes extensive interactions within the phosphoproteome and secretome. Keywords: phosphoproteomics, proteomics, exercise, myotubes, EasyPhos, signal transduction, mass spectrometry, berberine, AMPK, secretome