Phosphoproteomic analysis of human mesenchymal stromal cells during osteogenic differentiation.

Human mesenchymal stromal cells (hMSCs) are promising candidates for cell therapy and tissue regeneration. Knowledge of the molecular mechanisms governing hMSC commitment into osteoblasts is critical to the development of therapeutic applications for human bone diseases. Because protein phosphorylation plays a critical role in signaling transduction network, the purpose of this study is to elucidate the phosphoproteomic changes in hMSCs during early osteogenic lineage commitment. hMSCs cultured in osteogenic induction medium for 0, 1, 3, and 7 days were analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS). Surprisingly, we observed a dramatic loss of protein phosphorylation level after 1 day of osteogenic induction. Pathways analysis of these reduced phosphoproteins exhibited a high correlation with cell proliferation and protein synthesis pathways. During osteogenic differentiation, differentially expressed phosphoproteins demonstrated the dynamic alterations in cytoskeleton at the early...