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Crossroad control of cell proliferation and apoptosis by PEA‐15 phosphorylation homeostasis and allosteric regulation of protein conformations and interactions
Author(s) -
Wei Yufeng,
Crespo Sergio,
Hassan Sherouk
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.792.30
Subject(s) - fadd , phosphorylation , microbiology and biotechnology , phosphoprotein , serine , programmed cell death , biology , cell growth , protein phosphorylation , death domain , signal transduction , kinase , apoptosis , phosphorylation cascade , protein kinase a , biochemistry , caspase
Cell fate is determined by the relative tendency of cell proliferation and cell death. PEA‐15 (phosphoprotein enriched in astrocytes, 15 kD), a small, non‐catalytic, death‐effector domain (DED) containing protein, regulates both proliferation and apoptosis through protein‐protein interactions. PEA‐15 is widely expressed in different tissues and highly conserved among mammals, and the overall expression level of PEA‐15 is almost constant in most tissues. PEA‐15 contains two phosphorylation sites on the C‐terminal tail, Ser104 and Ser116, and the phosphorylation states of these two serine can vary significantly depending on cell and tissue types and/or cellular environment and conditions. Unphosphorylated PEA‐15 inhibits extracellular signal‐regulated kinase (ERK)‐dependent cell proliferation, while the doubly phosphorylated protein binds to Fas‐associated death domain (FADD) and blocks death receptor mediated apoptosis. Using advanced nuclear magnetic resonance (NMR) techniques, we previously reported a surprising conformational change of PEA‐15 DED upon interaction with ERK2. In addition, DED conformation is significantly modulated by the phosphorylation of the C‐terminal serine residues, which switches binding specificity from ERK1/2 to FADD. Based on our most recent results, we propose the phosphorylation homeostasis model, in which that the balance between phosphorylated and unphosphorylated PEA‐15 is strictly regulated in different cell types and tissues and controls the cell fate, any disruption of the delicate balance could lead to various diseases, such as cancers and neurodegenerative diseases. To test this hypothesis, we recently conducted quantitative Western blot to detect the phosphorylation states of PEA‐15 in various primary cells and cell lines, as well as the effects of PEA‐15 phosphorylation on the activation of caspases in the cells. We have also transfected wildtype, S104A/S116A (unphosphorylated mimic), and S104D/S116D (phosphorylated mimic) PEA‐15 into these cells. Using novel in‐cell NMR technique, we studied the conformation of these proteins within the cellular contents, where all its natural interactions are present. The effects of transfected proteins on apoptosis and activation of caspases have also been examined. Support or Funding Information NIH AREA R15CA179410 This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .