Journal Article

Oncogenic mutant RAS signaling activity is rescaled by the ERK/MAPK pathway

McCormick, Frank, Teragawa, Carolyn K, Silva, Jillian M, Albeck, John G, Gillies, Taryn E, Pargett, Michael

2020

Overview

Activating mutations in RAS are present in ~ 30% of human tumors, and the resulting aberrations in ERK/MAPK signaling play a central role in oncogenesis. However, the form of these signaling changes is uncertain, with activating RAS mutants linked to both increased and decreased ERK activation in vivo . Rationally targeting the kinase activity of this pathway requires clarification of the quantitative effects of RAS mutations. Here, we use live‐cell imaging in cells expressing only one RAS isoform to quantify ERK activity with a new level of accuracy. We find that despite large differences in their biochemical activity, mutant KRAS isoforms within cells have similar ranges of ERK output. We identify roles for pathway‐level effects, including variation in feedback strength and feedforward modulation of phosphatase activity, that act to rescale pathway sensitivity, ultimately resisting changes in the dynamic range of ERK activity while preserving responsiveness to growth factor stimuli. Our results reconcile seemingly inconsistent reports within the literature and imply that the signaling changes induced by RAS mutations early in oncogenesis are subtle. Synopsis Live‐cell imaging of ERK activity is used to compare wild type and mutant RAS isoforms at the single‐cell level. These experiments reconcile paradoxical reports on mutant RAS signaling and reveal mechanisms that normalize the dynamic range of ERK activity. Analysis of cells expressing single RAS isoforms enables quantitative comparison of their signaling activity. RAS mutants drive elevated baseline ERK activity but have attenuated peak stimulus responses. Differences in ERK signaling between RAS isoforms are smaller than expected from RAS biochemical properties. Dynamic regulation of phosphatase activity on ERK substrates contributes to the high dynamic range of ERK activity. Graphical Abstract Live‐cell imaging of ERK activity is used to compare wild type and mutant RAS isoforms at the single‐cell level. These experiments reconcile paradoxical reports on mutant RAS signaling and reveal mechanisms that normalize the dynamic range of ERK activity.

• Publisher: Nature Publishing Group UK,EMBO Press,John Wiley and Sons Inc,Springer Nature
• Subject: Animals / Cancer / Carcinogenesis - drug effects / Carcinogenesis - genetics / Cell adhesion & migration / Cell cycle / computational modeling / EMBO03 / EMBO37 / epidermal growth factor / Epidermal Growth Factor - pharmacology / Extracellular signal-regulated kinase / Feedback, Physiological - drug effects / Fluorescence Resonance Energy Transfer / Fluorescent Antibody Technique / FRET biosensor / Gene expression / Genes, ras - genetics / Growth factors / Image Processing, Computer-Assisted / Isoforms / Kinases / Kinetics / MAP kinase / MAP Kinase Signaling System - drug effects / MAP Kinase Signaling System - genetics / Mice / Mutants / Mutation / Phosphatase / Phosphoric Monoester Hydrolases - metabolism / Phosphorylation / Protein Isoforms / Proteins / RAS disease / ras Proteins - genetics / ras Proteins - metabolism / Signal transduction / Signaling / Single-Cell Analysis / single‐cell kinetics / Tumorigenesis / Tumors