p52Shc regulates the sustainability of ERK activation in a RAF-independent manner

Abstract

p52SHC (SHC) and GRB2 are adaptor proteins involved in the RAS/MAPK (ERK) pathway mediating signals from cell-surface receptors to various cytoplasmic proteins. To further examine their roles in signal transduction, we studied the translocation of fluorescently-labeled SHC and GRB2 to the cell surface, caused by the activation of ERBB receptors by heregulin (HRG). We simultaneously evaluated activated ERK translocation to the nucleus. Unexpectedly, the translocation dynamics of SHC were sustained when those of GRB2 were transient. The sustained localization of SHC positively correlated with the sustained nuclear localization of ERK, which became more transient after SHC knockdown. SHC-mediated PI3K activation was required to maintain the sustainability of the ERK translocation regulating MEK but not RAF. In cells overexpressing ERBB1, SHC translocation became transient, and the HRG-induced cell fate shifted from a differentiation to a proliferation bias. Our results indicate that SHC and GRB2 functions are not redundant, but that SHC plays the critical role in the temporal regulation of ERK activation.

Bilateral regulation of EGFR activity and local PI dynamics observed with superresolution microscopy

“…2 C). These values are consistent with the finding that cytoplasmic GRB2 is recruited to phosphorylated EGFR after EGF stimulation (Yoshizawa et al, 2021). These two experiments support the idea that the H-function analysis of the SMLM data reflects the degree of coaggregation, and that EGF stimulation reduced the colocalization rate of EGFR and PI(4,5)P 2 .…”

Evaluation of information flows in the RAS-MAPK system using transfer entropy measurements

“…1D). The early phase in the SOS and RAF activation is responsible for transient MEK/ERK activation following EGF signaling (Marshall, 1995; Kao, 2001; Yoshizawa et al, 2021). In the late phase, dephosphorylation and/or endocytosis of EGFR reduces signaling from EGFR (Monast et al 2012).…”

“…The translocation of SOS induces the activation of RAS, which, in turn, results in the translocation of RAF, a serine/threonine kinase and an effector of RAS, from the cytoplasm to the plasma membrane. These intracellular translocations of SOS and RAF can be visualized using a total internal fluorescence microscope with fluorescently labeled SOS and RAF molecules, specifically observing near the basal surface of cells (Nakamura et al, 2017; Yoshizawa et al, 2021).…”