SHP2 binds directly to SOS1 to enable RAS activation
The protein-tyrosine phosphatase SHP2 (PTPN11) regulates growth factor- and cytokine-induced RAS/ERK MAP kinase (MAPK) pathway activation, and aberrant SHP2 function causes developmental disorders and cancer1-5. It is widely believed that the catalytic activity of SHP2 is essential for pathway activation1,4,6-8. This view has shaped our interpretation of how germline PTPN11 mutations cause Noonan Syndrome (NS) and NS with Multiple Lentigines (NS-ML)2,9 and how somatic mutations contribute to myeloproliferative neoplasms and solid tumors1. Here we identify a previously undetected, protein-tyrosine phosphatase (PTP) activity-independent mechanism that revises our understanding of how SHP2 promotes RAS/ERK activation. We find that certain mutations of the nucleophilic cysteine that abolish catalytic activity still promote RAS/ERK pathway activation in normal and neoplastic mammalian cells, zebrafish embryos, and mice. Structural studies show that the SHP2 PTP domain binds directly to the Son of Sevenless 1 (SOS1) Dbl homology (DH) domain. Proximity labeling and super-resolution microscopy demonstrate that SHP2/SOS1 interaction occurs in cells and facilitates SOS1 translocation to the plasma membrane to form clusters. Our results overturn decades of dogma on SHP2 regulation of the RAS/ERK pathway and provide new insights into the mechanism of action of disease-associated PTPN11 mutations.