Dual Role of Phosphatidylinositol-3,4,5-trisphosphate in the Activation of Protein Kinase B

Stokoe, David; Stephens, Len R.; Copeland, Terry D.; Gaffney, Piers R. J.; Reese, Colin B.; Painter, Gavin F.; Holmes, Andrew B.; McCormick, Frank; Hawkins, Phillip T.

doi:10.1126/science.277.5325.567

Cited by 1,114 publications

(941 citation statements)

References 19 publications

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“…PDPK1 was first identified based on its ability to phosphorylate Thr308 of AKT. [30][31][32] However, conservation of aminoacid sequences similar to those surrounding Thr308 of AKT in the AGC family of Ser/Thr protein kinases suggested that PDPK1 may phosphorylate other AGC protein kinase family members, including PKC isoforms. In agreement with this, recent reports have demonstrated that PDPK1 can phosphorylate PKC isoforms.…”

Section: Resultsmentioning

confidence: 99%

Novel signaling axis for ROS generation during K-Ras-induced cellular transformation

et al. 2014

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Reactive oxygen species (ROS) are well known to be involved in oncogene-mediated cellular transformation. However, the regulatory mechanisms underlying ROS generation in oncogene-transformed cells are unclear. In the present study, we found that oncogenic K-Ras induces ROS generation through activation of NADPH oxidase 1 (NOX1), which is a critical regulator for the K-Ras-induced cellular transformation. NOX1 was activated by K-Ras-dependent translocation of p47 phox , a subunit of NOX1 to plasma membrane. Of note, PKCd, when it was activated by PDPK1, directly bound to the SH3-N domain of p47 phox and catalyzed the phosphorylation on Ser348 and Ser473 residues of p47 phox C-terminal in a K-Ras-dependent manner, finally leading to its membrane translocation. Notably, oncogenic K-Ras activated all MAPKs (JNK, ERK and p38); however, only p38 was involved in p47 phox -NOX1-dependent ROS generation and consequent transformation. Importantly, K-Ras-induced activation of p38 led to an activation of PDPK1, which then signals through PKCd, p47 phox and NOX1. In agreement with the mechanism, inhibition of p38, PDPK1, PKCd, p47 phox or NOX1 effectively blocked K-Ras-induced ROS generation, anchorage-independent colony formation and tumor formation. Taken together, our findings demonstrated that oncogenic K-Ras activates the signaling cascade p38/ PDPK1/PKCd/p47 phox /NOX1 for ROS generation and consequent malignant cellular transformation.

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Section: Resultsmentioning

confidence: 99%

Novel signaling axis for ROS generation during K-Ras-induced cellular transformation

et al. 2014

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“…PIP3 serves as substrate for the protein and lipid phosphatase activity-bearing tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome ten), which specifically removes the phosphate group in the D3 position of the inositol ring and thereby attenuates IIS pathway activity (Vanhaesebroeck and Alessi, 2000). Upon PIP3 production, Akt/ protein kinase B (PKB) translocates to the membrane mediated by binding of PIP3 to its PH domain and is fully activated by mTORC2 phosphorylating Ser473 in the C-terminal located hydrophobic motif (Hresko and Mueckler, 2005; and by 3 0 -phosphoinositide-dependent kinase-1 (PDK1) phosphorylating Thr308 in the activation/T-loop (Alessi et al, 1997;Stokoe et al, 1997;Stephens et al, 1998). Numerous downstream effectors of Akt/PKB have been described, among many others forkhead transcription factors, GSK3b, Bad and the cell cycle inhibitor p27 KIP1 (Brazil et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Stress and mTORture signaling

2006

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“…Stimulation of 293 cells with IGF-1 led to the phosphorylation of Akt at threonine 308 in the activation loop of the kinase and serine 473 in the carboxy-terminal tail, and phosphorylation of both sites was shown to contribute to Akt activation (Alessi et al, 1996). Recent studies have shown that at least two kinases, PDK1 and PDK2, are responsible for the growth factor-induced phosphorylation of Akt (Alessi et al, 1997a,b;Stokoe et al, 1997). It is interesting that the phosphorylation of Akt by PDK1 also depends on PI3-K-generated phospholipids (Alessi et al, 1997a,b;Stokoe et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies have shown that at least two kinases, PDK1 and PDK2, are responsible for the growth factor-induced phosphorylation of Akt (Alessi et al, 1997a,b;Stokoe et al, 1997). It is interesting that the phosphorylation of Akt by PDK1 also depends on PI3-K-generated phospholipids (Alessi et al, 1997a,b;Stokoe et al, 1997). This raises the question whether the phospholipids render Akt a good substrate for PDK1 or whether they activate PDK1.…”

Section: Introductionmentioning

confidence: 99%

Akt activation by growth factors is a multiple-step process: the role of the PH domain

et al. 1998

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The protein kinase encoded by the Akt proto-oncogene is activated by phospholipid binding, membrane translocation and phosphorylation. To address the relative roles of these mechanisms of Akt activation, we have employed a combination of genetic and pharmacological approaches. Transient transfection of NIH3T3 cells with wild-type Akt, pleckstrin homology (PH) domain mutants, generated on the basis of a PH domain structural model, and phosphorylation site Akt mutants provided evidence for a model of Akt activation consisting of three sequential steps: (1) a PH domain-dependent, growth factor-independent step, marked by constitutive phosphorylation of threonine 450 (T450) and perhaps serine 124 (S124), that renders the protein responsive to subsequent activation events; (2) a growth factor-induced, PI3-K-dependent membrane-translocation step; and (3) a PI3-K-dependent step, characterized by phosphorylation at T308 and S473, that occurs in the cell membrane and is required for activation. When forced to translocate to the membrane, wild-type Akt and PH domain Akt mutants that are defective in the ®rst step become constitutively active, suggesting that the purpose of this step is to prepare the protein for membrane translocation. Both growth factor stimulation and forced membrane translocation, however, failed to activate a T308A mutant. This, combined with the ®nding that T308D/S473D double mutant is constitutively active, suggests that the purpose of the three-step process of Akt activation is the phosphorylation of the protein at T308 and S473. The proposed model provides a framework for a comprehensive understanding of the temporal and spatial requirements for Akt activation by growth factors.

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Dual Role of Phosphatidylinositol-3,4,5-trisphosphate in the Activation of Protein Kinase B

Cited by 1,114 publications

References 19 publications

Novel signaling axis for ROS generation during K-Ras-induced cellular transformation

Novel signaling axis for ROS generation during K-Ras-induced cellular transformation

Stress and mTORture signaling

Akt activation by growth factors is a multiple-step process: the role of the PH domain

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