Quantitative phosphoproteome profiling of Wnt3a-mediated signaling network: indicating the involvement of ribonucleoside-diphosphate reductase M2 subunit phosphorylation at residue serine 20 in canonical Wnt signal transduction.

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Tang LY, Deng N, Wang LS, Dai J, Wang ZL, Jiang XS, Li SJ, Li L, Sheng QH, Wu DQ, Li L, Zeng R

Mol Cell Proteomics. 2007 Nov;6(11):1952-67. Epub 2007 Aug 12.

PubMed ID

17693683 [ View in PubMed

]

Abstract

The complexity of canonical Wnt signaling comes not only from the numerous components but also from multiple post-translational modifications. Protein phosphorylation is one of the most common modifications that propagates signals from extracellular stimuli to downstream effectors. To investigate the global phosphorylation regulation and uncover novel phosphoproteins at the early stages of canonical Wnt signaling, HEK293 cells were metabolically labeled with two stable isotopic forms of lysine and were stimulated for 0, 1, or 30 min with purified Wnt3a. After phosphoprotein enrichment and LC-MS/MS analysis, 1057 proteins were identified in all three time points. In total 287 proteins showed a 1.5-fold or greater change in at least one time point. In addition to many known Wnt signaling transducers, other phosphoproteins were identified and quantitated, implicating their involvement in canonical Wnt signaling. k-Means clustering analysis showed dynamic patterns for the differential phosphoproteins. Profile pattern and interaction network analysis of the differential phosphoproteins implicated the possible roles for those unreported components in Wnt signaling. Moreover 100 unique phosphorylation sites were identified, and 54 of them were quantitated in the three time points. Site-specific phosphopeptide quantitation revealed that Ser-20 phosphorylation on RRM2 increased upon 30-min Wnt3a stimulation. Further studies with mutagenesis, the Wnt reporter gene assay, and RNA interference indicated that RRM2 functioned downstream of beta-catenin as an inhibitor of Wnt signaling and that Ser-20 phosphorylation of RRM2 counteracted its inhibition effect. Our systematic profiling of dynamic phosphorylation changes responding to Wnt3a stimulation not only presented a comprehensive phosphorylation network regulated by canonical Wnt signaling but also found novel molecules and phosphorylation involved in Wnt signaling.

DrugBank Data that Cites this Article

Polypeptides

Name	UniProt ID
DNA ligase 1	P18858	Details
Ribonucleoside-diphosphate reductase subunit M2	P31350	Details
Microtubule-associated protein 4	P27816	Details
Triosephosphate isomerase	P60174	Details
Afadin	P55196	Details
SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A member 5	O60264	Details
Alpha-N-acetylgalactosaminidase	P17050	Details
Complement component 1 Q subcomponent-binding protein, mitochondrial	Q07021	Details