Oncogenic Kras induces spatiotemporally specific tissue deformation through converting pulsatile into sustained ERK activation.

Tissue regeneration and maintenance rely on coordinated stem cell behaviours. This orchestration can be impaired by oncogenic mutations leading to cancer. However, it is largely unclear how oncogenes perturb stem cells' orchestration to disrupt tissue. Here we used intravital imaging to investigate the mechanisms by which oncogenic Kras mutation causes tissue disruption in the hair follicle. Through longitudinally tracking hair follicles in live mice, we found that Kras(G12D), a mutation that can lead to squamous cell carcinoma, induces epithelial tissue deformation in a spatiotemporally specific manner, linked with abnormal cell division and migration. Using a reporter mouse capture real-time ERK signal dynamics at the single-cell level, we discovered that Kras(G12D), but not a closely related mutation Hras(G12V), converts ERK signal in stem cells from pulsatile to sustained. Finally, we demonstrated that interrupting sustained ERK signal reverts Kras(G12D)-induced tissue deformation through modulating specific features of cell migration and division.