Identification of the tuberous sclerosis complex-2 tumor suppressor gene product tuberin as a target of the phosphoinositide 3-kinase/akt pathway.
The S/T-protein kinases activated by phosphoinositide 3-kinase (PI3K) regulate a myriad of cellular processes. Here, we show that an approach using a combination of biochemistry and bioinformatics can identify substrates of these kinases. This approach identifies the tuberous sclerosis complex-2 gene product, tuberin, as a potential target of Akt/PKB. We demonstrate that, upon activation of PI3K, tuberin is phosphorylated on consensus recognition sites for PI3K-dependent S/T kinases. Moreover, Akt/PKB can phosphorylate tuberin in vitro and in vivo. We also show that S939 and T1462 of tuberin are PI3K-regulated phosphorylation sites and that T1462 is constitutively phosphorylated in PTEN(-/-) tumor-derived cell lines. Finally, we find that a tuberin mutant lacking the major PI3K-dependent phosphorylation sites can block the activation of S6K1, suggesting a means by which the PI3K-Akt pathway regulates S6K1 activity.
Manning
Brendan D
BD
Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
Tee
Andrew R
AR
Logsdon
M Nicole
MN
Blenis
John
J
Cantley
Lewis C
LC
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004789:Enzyme Activation; D017353:Gene Deletion; D006801:Humans; D051379:Mice; D008970:Molecular Weight; D009154:Mutation; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction; D013379:Substrate Specificity; D014402:Tuberous Sclerosis / Q000378:metabolism; D000077005:Tuberous Sclerosis Complex 2 Protein; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D010744:Phosphoric Monoester Hydrolases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012097:Repressor Proteins; D019893:Ribosomal Protein S6 Kinases; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; C000624653:TSC2 protein, human; C494918:AKT1 protein, human; C494929:PTEN protein, human