Article

A two-dimensional ERK-AKT signaling code for an NGF-triggered cell-fate decision.

Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA.
Molecular cell (Impact Factor: 14.46). 12/2011; 45(2):196-209. DOI: 10.1016/j.molcel.2011.11.023
Source: PubMed

ABSTRACT Growth factors activate Ras, PI3K, and other signaling pathways. It is not well understood how these signals are translated by individual cells into a decision to proliferate or differentiate. Here, using single-cell image analysis of nerve growth factor (NGF)-stimulated PC12 cells, we identified a two-dimensional phospho-ERK (pERK)-phospho-AKT (pAKT) response map with a curved boundary that separates differentiating from proliferating cells. The boundary position remained invariant when different stimuli were used or upstream signaling components perturbed. We further identified Rasa2 as a negative feedback regulator that links PI3K to Ras, placing the stochastically distributed pERK-pAKT signals close to the decision boundary. This allows for uniform NGF stimuli to create a subpopulation of cells that differentiates with each cycle of proliferation. Thus, by linking a complex signaling system to a simpler intermediate response map, cells gain unique integration and control capabilities to balance cell number expansion with differentiation.

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