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Active ERK 2 is sufficient to mediate growth arrest and differentiation signaling
Author(s) -
Wu Pui–Kei,
Hong Seung–Keun,
Yoon Seung–Hee,
Park Jong–In
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13197
Subject(s) - mapk/erk pathway , microbiology and biotechnology , autophosphorylation , signal transduction , kinase , phosphorylation , biology , lncap , transcription factor , chemistry , protein kinase a , cancer research , cancer cell , biochemistry , genetics , cancer , gene
Although extracellular signal‐regulated kinases ( ERK 1/2) have been shown to be required in Raf/ MEK / ERK pathway signaling, its sufficiency for mediating the pathway signaling has not been firmly established. In an effort to address this, we evaluated previously described ERK 2 mutants that exhibit enhanced autophosphorylation of TEY sites in the activation loop in terms of their ability to induce growth arrest and differentiation in LNC aP and PC 12 cells. We demonstrate that expression of ERK 2‐L73P/S151D, containing Lys73Pro and Ser151Asp substitutions that synergistically promote ERK autophosphorylation, is sufficient to induce growth arrest and differentiation, whereas expression of ERK 2‐I84A and ERK 2‐R65S/D319N is not as effective. When compared to the constitutively active MEK 1‐ΔN3/S218E/S222D, expression of ERK 2‐L73P/S151D only mildly increased ERK kinase activity in cells, as assessed using the ERK substrates p90 RSK and ETS domain‐containing protein (ELK1). However, ERK 2‐L73P/S151D expression effectively induced down‐regulation of androgen receptors, Retinoblastoma (Rb) protein and E2F1 transcription factor, and up‐regulation of p16 INK4A and p21 CIP1 , accompanied by cell‐cycle arrest and morphological differentiation in LNC aP cells and neurite‐like processes in PC 12 cells. These effects and the TEY site phosphorylation of ERK 2‐L73P/S151D were abrogated upon introduction of the active site‐disabling Lys52Arg mutation, suggesting that its autoactivation drives this signaling. Moreover, introduction of mutations Asp316/319Ala or Asp319Asn, which impair the common docking site/D‐domain‐based physical interaction of ERK , did not significantly affect ERK 2‐L73P/S151D signaling, suggesting that ERK 2 mediates growth arrest and differentiation independently of the conventional ERK –target interaction mechanism. Thus, our study presents convincing evidence of ERK sufficiency for Raf/ MEK / ERK signaling.