Modulation of specific protein expression levels by PTEN: identification of AKAP121, DHFR, G3BP, Rap1, and RCC1 as potential targets of PTEN.
The tumor suppressor PTEN is mutated in a high percentage of human cancers, and is implicated in pathways regulating cell growth, proliferation, survival, and migration. Despite significant advances, our understanding of its mechanisms of action remains incomplete. We have used a high-throughput proteomic immunoblotting approach to identify proteins whose expression levels are modulated by PTEN. Out of over 800 proteins screened, 22 proteins showed significant changes in expression. Five proteins that exhibited two-fold or greater changes in expression level were further characterized. AKAP121 and G3BP expression was reduced, while dihydrofolate reductase (DHFR), Rap1 and RCC1 expression was elevated in response to PTEN expression in a PTEN-null T-cell leukemia line. The phosphatase activity of PTEN was required for these effects. However, direct inhibition of PI-3 Kinase could mimic PTEN in modulating expression of DHFR, G3BP, Rap1 and RCC1, but not AKAP121. Real-time PCR showed that the effects of PTEN were primarily post-transcriptional, and would not have been revealed by mRNA-based screens. We conclude from these data that PTEN can modulate the expression level of a number of different proteins. The identified proteins have the potential to serve as previously unrecognized effectors of PTEN, and suggest the existence of additional complexity in the modes by which PTEN can regulate cellular biology.
Huang
Yanping
Y
Laboratory of Cellular and Molecular Biology, National Institute on Aging, IRP/NIH/DHHS, 5600 Nathan Shock Drive, MSC-12, Baltimore, MD 21224, USA.
Wernyj
Roman P
RP
Norton
Darrell D
DD
Precht
Patricia
P
Seminario
Maria-Cristina
MC
Wange
Ronald L
RL
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis*; D002352:Carrier Proteins / Q000032:analysis*; D018797:Cell Cycle Proteins / Q000032:analysis*; D004265:DNA Helicases; D020662:Guanine Nucleotide Exchange Factors / Q000032:analysis*; D006801:Humans; D019169:Jurkat Cells; D009687:Nuclear Proteins / Q000032:analysis*; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases / Q000032:analysis; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology*; D000075223:Poly-ADP-Ribose Binding Proteins; D040901:Proteomics; D020365:RNA Helicases; D000067776:RNA Recognition Motif Proteins; D013762:Tetrahydrofolate Dehydrogenase / Q000032:analysis*; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins / Q000502:physiology*
D054758:A Kinase Anchor Proteins; C105137:AKAP1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D020662:Guanine Nucleotide Exchange Factors; D009687:Nuclear Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; C062521:RCC1 protein, human; D000067776:RNA Recognition Motif Proteins; D025521:Tumor Suppressor Proteins; D013762:Tetrahydrofolate Dehydrogenase; D019869:Phosphatidylinositol 3-Kinases; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D004265:DNA Helicases; C116070:G3BP1 protein, human; D020365:RNA Helicases