Piezo1 activates non-canonical EGFR endocytosis and signaling.

SummaryEGFR-ERK signaling controls cell cycle progression during development, homeostasis, and disease. Both the soluble extracellular ligand, EGF, and mechanical inputs like matrix stiffness, cell adhesion, or stretch activate EGFR-ERK signaling. However, the molecules transducing mechanical forces into EGFR signaling remain unidentified. We previously found that stretch promotes mitosis by mechanically activating the ion channel Piezo1 to trigger ERK signaling. Here, we show that Piezo1 provides the missing link to mechanical EGFR-ERK activation. Both EGF ligand and mechanical or agonist activation of Piezo1 trigger clathrin-mediated endocytosis of EGFR and ERK activation, established markers of EGFR signaling. However, while EGF stimulation requires canonical EGFR tyrosine autophosphorylation, EGFR activation by Piezo1 instead requires Src-p38 kinase-dependent serine EGFR phosphorylation. Additionally, in contrast to the homeostatic signaling downstream EGF activation, direct agonist stimulation of Piezo1 promoted cell cycle re-entry and proliferation in mouse airway epithelia ex vivo via long-term nuclear accumulation of ERK, AP-1 (FOS and JUN), and YAP, typical of regenerative and malignant signaling. Our results suggest two modes of EGFR signaling: basal EGF-dependent signaling via tyrosine autophosphorylation and mechanically activated Piezo1-dependent signaling via serine phosphorylation, resulting in sustained proliferation, critical to repair, regeneration, and cancer growth. Given the limited success of tyrosine kinase inhibitors in cancer, this new axis may provide a more relevant target for cancer treatment.