| First Author | Mounir Z | Year | 2009 |
| Journal | Sci Signal | Volume | 2 |
| Issue | 102 | Pages | ra85 |
| PubMed ID | 20029030 | Mgi Jnum | J:259490 |
| Mgi Id | MGI:6141402 | Doi | 10.1126/scisignal.2000389 |
| Citation | Mounir Z, et al. (2009) Tumor suppression by PTEN requires the activation of the PKR-eIF2alpha phosphorylation pathway. Sci Signal 2(102):ra85 |
| abstractText | Inhibition of protein synthesis by phosphorylation of the alpha subunit of eukaryotic translation initiation factor 2 (eIF2) at Ser(51) occurs as a result of the activation of a family of kinases in response to various forms of stress. Although some consequences of eIF2alpha phosphorylation are cytoprotective, phosphorylation of eIF2alpha by RNA-dependent protein kinase (PKR) is largely proapoptotic and tumor suppressing. Phosphatase and tensin homolog deleted from chromosome 10 (PTEN) is a tumor suppressor protein that is mutated or deleted in various human cancers, with functions that are mediated through phosphatase-dependent and -independent pathways. Here, we demonstrate that the eIF2alpha phosphorylation pathway is downstream of PTEN. Inactivation of PTEN in human melanoma cells reduced eIF2alpha phosphorylation, whereas reconstitution of PTEN-null human glioblastoma or prostate cancer cells with either wild-type PTEN or phosphatase-defective mutants of PTEN induced PKR activity and eIF2alpha phosphorylation. The antiproliferative and proapoptotic effects of PTEN were compromised in mouse embryonic fibroblasts that lacked PKR or contained a phosphorylation-defective variant of eIF2alpha. Induction of the pathway leading to phosphorylation of eIF2alpha required an intact PDZ-binding motif in PTEN. These findings establish a link between tumor suppression by PTEN and inhibition of protein synthesis that is independent of PTEN''s effects on phosphoinositide 3''-kinase signaling. |
