Phosphoproteomic analysis identifies insulin enhancement of discoidin domain receptor 2 phosphorylation

The discoidin domain receptors (DDRs) are collagen binding receptor tyrosine kinases that play important roles in cell migration, invasion and adhesion. Crosstalk between growth factor signaling and components of the extracellular matrix are drivers of cellular function but the integrated signaling networks downstream of such crosstalk events have not been extensively characterized. In this report, we have employed mass spectrometry-based quantitative phosphotyrosine analysis to identify crosstalk between DDR2 and the insulin receptor. Our phosphoproteomic analysis reveals a cluster of phosphorylation sites in which collagen and insulin cooperate to enhance phosphotyrosine levels. Importantly, Y740 on the DDR2 catalytic loop was found in this cluster indicating that insulin acts to promote collagen I signaling by increasing the activity of DDR2. Furthermore, we identify two additional migration associated proteins that are candidate substrates downstream of DDR2 activation. Our data suggests that insulin promotes collagen I signaling through the upregulation of DDR2 phosphorylation which may have important consequences in DDR2 function in health and disease.