Open AccessRapid and sustained nuclear–cytoplasmic ERK oscillations induced by epidermal growth factor
Author(s) -
Shankaran Harish,
Ippolito Danielle L,
Chrisler William B,
Resat Haluk,
Bollinger Nikki,
Opresko Lee K,
Wiley H Steven
Publication year - 2009
Publication title -
molecular systems biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.523
H-Index - 148
ISSN - 1744-4292
DOI - 10.1038/msb.2009.90
Subject(s) - mapk/erk pathway , biology , microbiology and biotechnology , phosphorylation , epidermal growth factor , cytoplasm , fusion protein , transfection , mapk cascade , cell culture , recombinant dna , biochemistry , genetics , gene
Although the ERK pathway has a central role in the response of cells to growth factors, its regulatory structure and dynamics are incompletely understood. To investigate ERK activation in real time, we expressed an ERK–GFP fusion protein in human mammary epithelial cells. On EGF stimulation, we observed sustained oscillations of the ERK–GFP fusion protein between the nucleus and cytoplasm with a periodicity of ∼15 min. The oscillations were persistent (>45 cycles), independent of cell cycle phase, and were highly dependent on cell density, essentially disappearing at confluency. Oscillations occurred even at ligand doses that elicited very low levels of ERK phosphorylation, and could be detected biochemically in both transfected and nontransfected cells. Mathematical modeling revealed that negative feedback from phosphorylated ERK to the cascade input was necessary to match the robustness of the oscillation characteristics observed over a broad range of ligand concentrations. Our characterization of single‐cell ERK dynamics provides a quantitative foundation for understanding the regulatory structure of this signaling cascade.