Specific binding of the Akt-1 protein kinase to phosphatidylinositol 3,4,5-trisphosphate without subsequent activation

James, Sarah; Downes, C P; Gigg, Roy; Grove, Simon J. A.; Holmes, Andrew B.; Alessi, Dario R.

doi:10.1042/bj3150709

Cited by 304 publications

(241 citation statements)

References 39 publications

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“…Our observations with FRET-based probes are in favor of this model: The increase in PtdIns(3,4)P 2 and activation of Akt were observed at the peripheral plasma membrane such as nascent lamellipodia, whereas an increase in PtdIns(3,4,5)P 3 was observed more diffusely at the plasma membrane, including the dorsal surface of the cells (Figure 4, D-F). On the contrary, in support of PtdIns(3,4,5)P 3 being the critical second messenger, PtdIns(3,4,5)P 3 is reported to bind to Akt with slightly higher affinity than does PtdIns(3,4)P 2 (James et al, 1996;Frech et al, 1997). Furthermore, PDK1 has a substantially higher affinity for PtdIns(3,4,5)P 3 than for PtdIns(3,4)P 2 (Stokoe et al, 1997) and needs to interact with the plasma membrane to phosphorylate Akt efficiently (Anderson et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Akt–PDK1 Complex Mediates Epidermal Growth Factor-induced Membrane Protrusion through Ral Activation

Yoshizaki

Mochizuki

Gotoh

et al. 2007

MBoC

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We studied the spatiotemporal regulation of Akt (also called protein kinase B), phosphatidylinositol-3,4-bisphosphate [PtdIns(3,4)P 2 ], and phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P 3 ] by using probes based on the principle of fluorescence resonance energy transfer. On epidermal growth factor (EGF) stimulation, the amount of PtdIns(3,4,5)P 3 was increased diffusely in the plasma membrane, whereas that of PtdIns(3,4)P 2 was increased more in the nascent lamellipodia than in the plasma membrane of the central region. The distribution and time course of Akt activation were similar to that of increased PtdIns(3,4)P 2 levels, which were most prominent in the nascent lamellipodia. Moreover, we found that upon EGF stimulation 3-phosphoinositide-dependent protein kinase-1 (PDK1) was also recruited to nascent lamellipodia in an Akt-dependent manner. Because PDK1 is known to activate Ral GTPase and because Ral is required for EGF-induced lamellipodial protrusion, we speculated that the PDK1-Akt complex may be indispensable for the induction of lamellipodia. In agreement with this idea, EGF-induced lamellipodia formation was promoted by the overexpression of Akt and inhibited by an Akt inhibitor or a Ral-binding domain of Sec5. These results identified the Akt-PDK1 complex as an upstream positive regulator of Ral GTPase in the induction of lamellipodial protrusion. INTRODUCTIONClass I phosphoinositide 3-kinase (PI3K) is a key mediator of intracellular signaling pathways that regulate actin cytoskeletal reorganization and polarized cell migration. Activated PI3K phosphorylates phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P 2 ] to generate phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P 3 ], which, in turn, activates a variety of pleckstrin homology (PH) domain-containing proteins such as Akt (also called protein kinase B) (Saltiel and Pessin, 2002;Sulis and Parsons, 2003). PtdIns(3,4,5)P 3 is dephosphorylated to yield PtdIns(4,5)P 2 by a tumor suppressor protein, phosphatase and tensin homolog deleted in chromosome 10 (PTEN), which is frequently mutated or deleted in various human cancers (Sulis and Parsons, 2003). The resulting PTEN deficiency causes accumulation of PtdIns(3,4,5)P 3 in cells, and, as a consequence, an increase in cell motility in fibroblasts (Liliental et al., 2000;Higuchi et al., 2001;Hafizi et al., 2005). Another dephosphorylated derivative of PtdIns (3,4,5)P 3 is PtdIns(3,4)P 2 produced by phosphoinositide 5-phosphatases, including Src homology 2-containing inositol-5-phosphatase (SHIP). This PtdIns(3,4)P 2 also binds to various PH domain-containing proteins, which overlap significantly to those bound to PtdIns(3,4,5)P 3 (Lemmon and Ferguson, 2000;Maffucci and Falasca, 2001).Among many PH domain-containing proteins, a serinethreonine kinase, Akt, has been studied most extensively. Akt has been implicated in the control of diverse cellular functions, including glucose metabolism, gene transcription, cell proliferation, and apoptosis (Brazil et al., 2004;Fayard et al., 2005)...

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Section: Discussionmentioning

confidence: 99%

Akt–PDK1 Complex Mediates Epidermal Growth Factor-induced Membrane Protrusion through Ral Activation

Yoshizaki

Mochizuki

Gotoh

et al. 2007

MBoC

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“…Recently, many such reporters have been developed for measuring signaling molecules like Ca 2ϩ , cGMP, cAMP, or signaling events such as protein phosphorylation (14,15). For the sensing component, we chose the PH domain of Akt that binds specifically to two of the major PI3K products, namely PIP 3 and PI(3,4)P 2 (18,19). Crystal structure of this PH domain complexed to soluble inositol (1,3,4,5)-tetrakisphosphate (IP 4 ) (20) shows that this motif forms a bowl-like structure lined with basic residues into which the highly negatively charged headgroup is accommodated.…”

Section: Resultsmentioning

confidence: 99%

Signal propagation from membrane messengers to nuclear effectors revealed by reporters of phosphoinositide dynamics and Akt activity

Ananthanarayanan

Zhang

2005

Proc. Natl. Acad. Sci. U.S.A.

103

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“…We believe that the high molecular weight phosphoprotein is complexed with weakly phosphorylated PLCg-1. The reason for the weak phosphorylation of PLCg-1 could be dephosphorylation by internal phosphatases (James et al, 1996) and indeed in the presence of vanadate, a phosphatase inhibitor, PLCg-1 phosphorylation was more readily detectable (not shown).…”

Section: Defective Fgf Signaling Abrogates Akt/pkb and Plcg1 Activationmentioning

confidence: 97%

Fibroblast growth factor (FGF) signaling through PI 3-kinase and Akt/PKB is required for embryoid body differentiation

et al. 2000

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The role of FGF signaling in early epithelial di erentiation was investigated in ES (embryonic stem) cell derived embryoid bodies. A dominant negative ®broblast growth factor receptor (FGFR) mutation was created by stably introducing into ES cells an Fgfr2 cDNA, truncated in its enzymatic domains. These cells failed to di erentiate into cystic embryoid bodies. No epithelial di erentiation and cavitation morphogenesis could be observed, in the mutant, although its rate of cell proliferation remained unchanged. This phenotype was associated with a signi®cant decrease in the activation of Akt/PKB and PLCg-1, as compared to the wild type, while the activation of MAPK/Erk was less a ected. Requirement for PI 3-kinase signaling in embryoid body di erentiation was demonstrated by speci®c inhibitors. Akt/PKB activation was abrogated by wortmannin in short-term experiments. In long-term cultures Ly294002 inhibited the di erentiation of ES cells into embryoid bodies. Our data demonstrate that for early epithelial di erentiation FGF signaling is required through the PI 3-kinase-Akt/ PKB pathway.

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Specific binding of the Akt-1 protein kinase to phosphatidylinositol 3,4,5-trisphosphate without subsequent activation

Cited by 304 publications

References 39 publications

Akt–PDK1 Complex Mediates Epidermal Growth Factor-induced Membrane Protrusion through Ral Activation

Akt–PDK1 Complex Mediates Epidermal Growth Factor-induced Membrane Protrusion through Ral Activation

Signal propagation from membrane messengers to nuclear effectors revealed by reporters of phosphoinositide dynamics and Akt activity

Fibroblast growth factor (FGF) signaling through PI 3-kinase and Akt/PKB is required for embryoid body differentiation

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