Analyses of PDE-Regulated Phosphoproteomes Reveal Unique and Specific Camp-Signaling Modules in T Cells
Analyses of PDE-regulated phosphoproteomes reveal unique and specific cAMP-signaling modules in T cells Michael-Claude G. Beltejara, Ho-Tak Laua, Martin G. Golkowskia, Shao-En Onga, and Joseph A. Beavoa,1 aDepartment of Pharmacology, University of Washington, Seattle, WA 98195 Contributed by Joseph A. Beavo, May 28, 2017 (sent for review March 10, 2017; reviewed by Paul M. Epstein, Donald H. Maurice, and Kjetil Tasken) Specific functions for different cyclic nucleotide phosphodiester- to bias T-helper polarization toward Th2, Treg, or Th17 pheno- ases (PDEs) have not yet been identified in most cell types. types (13, 14). In a few cases increased cAMP may even potentiate Conventional approaches to study PDE function typically rely on the T-cell activation signal (15), particularly at early stages of measurements of global cAMP, general increases in cAMP- activation. Recent MS-based proteomic studies have been useful dependent protein kinase (PKA), or the activity of exchange in characterizing changes in the phosphoproteome of T cells under protein activated by cAMP (EPAC). Although newer approaches various stimuli such as T-cell receptor stimulation (16), prosta- using subcellularly targeted FRET reporter sensors have helped glandin signaling (17), and oxidative stress (18), so much of the define more compartmentalized regulation of cAMP, PKA, and total Jurkat phosphoproteome is known. Until now, however, no EPAC, they have limited ability to link this regulation to down- information on the regulation of phosphopeptides by PDEs has stream effector molecules and biological functions. To address this been available in these cells. problem, we have begun to use an unbiased mass spectrometry- Inhibitors of cAMP PDEs are useful tools to study PKA/EPAC- based approach coupled with treatment using PDE isozyme- mediated signaling, and selective inhibitors for each of the 11 PDE – selective inhibitors to characterize the phosphoproteomes of the families have been developed (19 21).
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