Phosphoproteomic analysis of signaling downstream of p85β

p85β is a regulatory subunit of phosphatidylinositol 3-kinase. The signaling mechanism of p85β is poorly understood. Quantitative mass spectrometry-based phosphoproteomic analysis was therefore performed to reveal proteins with an altered phosphorylation status upon PIK3R2 depletion in ovarian cancer cell line SKOV3. This profiling yielded 90 unique altered phosphopeptides, mapping to 29 and 45 proteins whose levels were downregulated or upregulated at P<0.05 by PIK3R2-specific siRNA, respectively. We observed significant enrichment of proteins in ubiquitin-mediated proteolysis and autophagy regulation, suggesting a role of p85β in regulating these cellular processes.