Endosomal cAMP production impacts the broad cellular phosphoproteome
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ABSTRACT: Endosomal signaling from G protein-coupled receptors (GPCRs) has emerged as a novel paradigm with important pharmacological and physiological implications. Yet, our knowledge of the functional consequences of activating intracellular GPCRs is incomplete. To address this gap, we combined an optogenetic approach for site-specific generation of the prototypical second messenger cyclic AMP (cAMP) with unbiased phosphoproteomic analysis. We identified 218 unique sites that either increased or decreased in phosphorylation upon cAMP production. We next determined that the compartment of signaling origin impacted the regulation of the entire repertoire of targets in that, remarkably, endosome-derived cAMP led to more robust changes in phosphorylation for all targets regardless of their annotated sub-cellular localization. Furthermore, we observed that proteins that are dephosphorylated in response to cAMP accumulation exhibited disproportionately strong bias towards endosomal over plasma membrane signaling. Through bioinformatics analysis, we established that this specific set of targets are substrates for protein phosphatase 2A, PP2A-B56δ, and propose compartmentalized activation of PP2A as the likely underlying mechanism. Altogether, our study extends the concept that endosomal signaling is a significant functional contributor to cellular responsiveness by establishing a unique role for localized cAMP production in defining categorically distinct phosphoresponses.
INSTRUMENT(S): LTQ Orbitrap Elite
ORGANISM(S): Homo Sapiens (human)
TISSUE(S): Cell Culture
SUBMITTER: Jeffrey Johnson
LAB HEAD: Mark von Zastrow
PROVIDER: PXD025775 | Pride | 2021-06-15
REPOSITORIES: Pride
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