Spatially Separate Docking Sites on ERK2 Regulate Distinct Signaling Events In Vivo

Abstract

Inhibitors of the oncogenic Ras-MAPK pathway have been intensely pursued as therapeutics. Targeting this pathway, however, presents challenges due to the essential role of MAPK in homeostatic functions. The phosphorylation and activation of MAPK substrates is regulated by protein-protein interactions with MAPK docking sites. Active ERK1/2 (extracellular signal-regulated kinase 1/2)-MAPKs localize to effectors containing DEF (docking site for ERK, (F)/(Y) -X-(F)/(Y) -P)- or D-domain (docking domain) motifs. We have examined the in vivo activity of ERK2 mutants with impaired ability to signal via either docking site. Mutations in the DEF-domain binding pocket prevent activation of DEF-domain-containing effectors but not RSK (90 kDa ribosomal S6 kinase), which contains a D domain. Conversely, mutation of the ERK2 CD domain, which interacts with D domains, prevents RSK activation but not DEF-domain signaling. Uncoupling docking interactions does not compromise ERK2 phosphotransferase activity. ERK2 DEF mutants undergo regulated nuclear translocation but are defective for Elk-1/TCF transactivation and target gene induction. Thus, downstream branches of ERK2 signaling can be selectively inhibited without blocking total pathway activity. Significantly, several protooncogenes contain DEF domains and are regulated by ERK1/2. Therefore, disrupting ERK-DEF domain interactions could be an alternative to inhibiting oncogenic Ras-MAPK signaling.

MAP kinases and the control of nuclear events

“…Emerging studies in the last few years have provided compelling evidence that these binding sites for docking motifs play a key role in determining the substrate specificity of MAPKs (Biondi and Nebreda, 2003;Tanoue and Nishida, 2003;Dimitri et al, 2005;Ho et al, 2006). The best described docking motif is known as docking site for ERK and JNK (DEJL) or D motif (Chang et al, 2002;Lee et al, 2004;Callaway et al, 2005;Zhou et al, 2006) which posses the general pattern (Arg/Lys) 1À2 -(X) 2-6 -+ A -X-+ B , where + A and + B are hydrophobic residuesleucine (Leu), isoleucine (Ile) or valine (Val).…”

Down-regulation of CMTM8 Induces Epithelial-to-Mesenchymal Transition-like Changes via c-MET/Extracellular Signal-regulated Kinase (ERK) Signaling

“…ERK contains a DEF motif-binding pocket and a common D-domain that bind DEF motifs and D-domains, respectively. Single point mutations on the ERK2 DEF motif-binding pocket or the ERK2 common D-domain can impair the signaling to DEF motif-or D-domain-containing interactors of ERK2, respectively, without greatly affecting its overall kinase activity (19). A recent study revealed that ERK2 (but not ERK1) overexpression is sufficient to induce EMT via its DEF motif signaling in human breast epithelial cells (16).…”

Interfering with MAP Kinase Docking Interactions: Implications and Perspectives for the p38 Route

“…68 In agreement with these results, D-peptides impair signal transduction towards the docking-dependent substrate Rsk while preserving the ability to phosphorylate and activate substrates more dependent on FxF docking interactions, such as c-fos, that is inhibited by DEF (FxF)-peptides. 69 These results demonstrate that transmission of signals towards distinct subsets of partners are ruled by specific docking interactions, such as those of FxF (DEF) vs. ØxØ (D) motifs, and can thus be functionally separated in cells without grossly affecting MAPK catalytic activity.…”