title: Phosphoprotein enriched in astrocytes 15 kDa (PEA-15) reprograms growth factor signaling by inhibiting threonine phosphorylation of fibroblast receptor substrate 2alpha.
abstract: Changes in cellular expression of phosphoprotein enriched in astrocytes of 15 kDa (PEA-15) are linked to insulin resistance, tumor cell invasion, and cellular senescence; these changes alter the activation of the extracellular signal-regulated kinase (ERK)1/2 mitogen-activated protein (MAP) kinase pathway. Here, we define the mechanism whereby increased PEA-15 expression promotes and sustains ERK1/2 activation. PEA-15 binding prevented ERK1/2 membrane recruitment and threonine phosphorylation of fibroblast receptor substrate 2alpha (FRS2alpha), a key link in fibroblast growth factor (FGF) receptor activation of ERK1/2. This reduced threonine phosphorylation led to increased FGF-induced tyrosine phosphorylation of FRS2alpha, thereby enhancing downstream signaling. Conversely, short hairpin RNA-mediated depletion of endogenous PEA-15 led to reduced FRS2alpha tyrosine phosphorylation. Thus, PEA-15 interrupts a negative feedback loop that terminates growth factor receptor signaling downstream of FRS2alpha. This is the dominant mechanism by which PEA-15 activates ERK1/2 because genetic deletion of FRS2alpha blocked the capacity of PEA-15 to activate the MAP kinase pathway. Thus, PEA-15 prevents ERK1/2 localization to the plasma membrane, thereby inhibiting ERK1/2-dependent threonine phosphorylation of FRS2alpha to promote activation of the ERK1/2 MAP kinase pathway.
authors.affiliation: Department of Medicine, University of California San Diego, La Jolla, CA 92093-0726, USA.
authors.forename: Jacob R
authors.initials: JR
authors.lastname: Haling
authors.forename: Fen
authors.initials: F
authors.lastname: Wang
authors.forename: Mark H
authors.initials: MH
authors.lastname: Ginsberg
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011487:Protein Conformation; D013912:Threonine / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; C488187:FRS2alpha protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C092039:PEA15 protein, human; D010750:Phosphoproteins; D013912:Threonine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3