Serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit gamma isoform (PP2A B subunit isoform B'-gamma) (PP2A B subunit isoform B56-gamma) (PP2A B subunit isoform PR61-gamma) (PP2A B subunit isoform R5-gamma) (Renal carcinoma antigen NY-REN-29) [KIAA0044]
The insulin/TOR signaling pathway plays a crucial role in animal homeostasis, sensing nutrient status to regulate organismal growth and metabolism. We identify here the Drosophila B' regulatory subunit of PP2A (PP2A-B') as a novel, conserved component of the insulin pathway that specifically targets the PP2A holoenzyme to dephosphorylate S6K. PP2A-B' knockout flies have elevated S6K phosphorylation and exhibit phenotypes typical of elevated insulin signaling such as reduced total body triglycerides and reduced longevity. We show that PP2A-B' interacts with S6K both physically and genetically. The human homolog of PP2A-B', PPP2R5C, also counteracts S6K1 phosphorylation, indicating a conserved mechanism in mammals. Since S6K affects development of cancer and metabolic disease, our data identify PPP2R5C as a novel factor of potential medical relevance.
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