Effects of oncogenic p110α subunit mutations on the lipid kinase activity of phosphoinositide 3-kinase

2007 ◽  
Vol 409 (2) ◽  
pp. 519-524 ◽  
Author(s):  
Jeffrey D. Carson ◽  
Glenn Van Aller ◽  
Ruth Lehr ◽  
Robert H. Sinnamon ◽  
Robert B. Kirkpatrick ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Hot Spot ◽  
Fold Increase ◽  
Biochemical Activity ◽  
Gene Encoding ◽  
Lipid Kinase ◽  
Kinase Activation ◽  
Pi3k Signalling ◽  
Transforming Activity ◽  
Phosphoinositide 3 Kinase

The PIK3CA gene, encoding the p110α catalytic subunit of Class IA PI3Ks (phosphoinositide 3-kinases), is frequently mutated in many human tumours. The three most common tumour-derived alleles of p110α, H1047R, E542K and E545K, were shown to potently activate PI3K signalling in human epithelial cells. In the present study, we examine the biochemical activity of the recombinantly purified PI3K oncogenic mutants. The kinetic characterizations of the wt (wild-type) and the three ‘hot spot’ PI3K mutants show that the mutants all have approx. 2-fold increase in lipid kinase activities. Interestingly, the phosphorylated IRS-1 (insulin receptor substrate-1) protein shows activation of the lipid kinase activity for the wt and H1047R but not E542K and E545K PI3Kα, suggesting that these mutations represent different mechanisms of lipid kinase activation and hence transforming activity in cancer cells.

scholarly journals Phosphoinositide 3-kinase γ mediates Jun kinase activation via its lipid-kinase activity

2004 ◽  
Vol 44 (1) ◽  
pp. 299-308
Author(s):  
Regina Pietrucha ◽  
Ignacio Rubio ◽  
Matthias P. Wymann ◽  
Reinhard Wetzker
Keyword(s):  
Kinase Activity ◽  
Lipid Kinase ◽  
Kinase Activation ◽  
Jun Kinase ◽  
Phosphoinositide 3 Kinase

scholarly journals Fission Yeast Rad26 Is a Regulatory Subunit of the Rad3 Checkpoint Kinase

2002 ◽  
Vol 13 (2) ◽  
pp. 480-492 ◽  
Author(s):  
Tom D. Wolkow ◽  
Tamar Enoch
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Fission Yeast ◽  
Complex Analysis ◽  
Kinase Activity ◽  
Regulatory Subunit ◽  
Kinase Activation ◽  
Checkpoint Proteins ◽  
Cycle Arrest ◽  
Phosphoinositide 3 Kinase

Fission yeast Rad3 is a member of a family of phosphoinositide 3-kinase -related kinases required for the maintenance of genomic stability in all eukaryotic cells. In fission yeast, Rad3 regulates the cell cycle arrest and recovery activities associated with the G2/M checkpoint. We have developed an assay that directly measures Rad3 kinase activity in cells expressing physiological levels of the protein. Using the assay, we demonstrate directly that Rad3 kinase activity is stimulated by checkpoint signals. Of the five other G2/M checkpoint proteins (Hus1, Rad1, Rad9, Rad17, and Rad26), only Rad26 was required for Rad3 kinase activity. Because Rad26 has previously been shown to interact constitutively with Rad3, our results demonstrate that Rad26 is a regulatory subunit, and Rad3 is the catalytic subunit, of the Rad3/Rad26 kinase complex. Analysis of Rad26/Rad3 kinase activation in rad26.T12, a mutant that is proficient for cell cycle arrest, but defective in recovery, suggests that these two responses to checkpoint signals require quantitatively different levels of kinase activity from the Rad3/Rad26 complex.

scholarly journals Class I Phosphoinositide 3-Kinase PIK3CA/p110α and PIK3CB/p110β Isoforms in Endometrial Cancer

2018 ◽  
Vol 19 (12) ◽  
pp. 3931 ◽  
Author(s):  
Fatemeh Mazloumi Gavgani ◽  
Victoria Smith Arnesen ◽  
Rhîan Jacobsen ◽  
Camilla Krakstad ◽  
Erling Hoivik ◽  
...  
Keyword(s):  
Endometrial Cancer ◽  
Gene Copy Number ◽  
Biochemical Properties ◽  
Class I ◽  
Gene Copy ◽  
Gene Encoding ◽  
Cellular Processes ◽  
Pi3k Signalling ◽  
Phosphoinositide 3 Kinase ◽  
Phosphatase And Tensin Homologue

The phosphoinositide 3-kinase (PI3K) signalling pathway is highly dysregulated in cancer, leading to elevated PI3K signalling and altered cellular processes that contribute to tumour development. The pathway is normally orchestrated by class I PI3K enzymes and negatively regulated by the phosphatase and tensin homologue, PTEN. Endometrial carcinomas harbour frequent alterations in components of the pathway, including changes in gene copy number and mutations, in particular in the oncogene PIK3CA, the gene encoding the PI3K catalytic subunit p110α, and the tumour suppressor PTEN. PIK3CB, encoding the other ubiquitously expressed class I isoform p110β, is less frequently altered but the few mutations identified to date are oncogenic. This isoform has received more research interest in recent years, particularly since PTEN-deficient tumours were found to be reliant on p110β activity to sustain transformation. In this review, we describe the current understanding of the common and distinct biochemical properties of the p110α and p110β isoforms, summarise their mutations and highlight how they are targeted in clinical trials in endometrial cancer.

scholarly journals p110α Hot Spot Mutations E545K and H1047R Exert Metabolic Reprogramming Independently of p110α Kinase Activity

2015 ◽  
Vol 35 (19) ◽  
pp. 3258-3273 ◽  
Author(s):  
Aditi Chaudhari ◽  
Daniel Krumlinde ◽  
Annika Lundqvist ◽  
Levent M. Akyürek ◽  
Sashidhar Bandaru ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Human Cancer ◽  
Hot Spot ◽  
Metabolic Reprogramming ◽  
Whole Body ◽  
Lipid Kinase ◽  
Glycogen Accumulation ◽  
Adenoviral Gene Transfer ◽  
Hepatic Expression

The phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) catalytic subunit p110α is the most frequently mutated kinase in human cancer, and the hot spot mutations E542K, E545K, and H1047R are the most common mutations in p110α. Very little is known about the metabolic consequences of the hot spot mutations of p110αin vivo. In this study, we used adenoviral gene transfer in mice to investigate the effects of the E545K and H1047R mutations on hepatic and whole-body glucose metabolism. We show that hepatic expression of these hot spot mutations results in rapid hepatic steatosis, paradoxically accompanied by increased glucose tolerance, and marked glycogen accumulation. In contrast, wild-type p110α expression does not lead to hepatic accumulation of lipids or glycogen despite similar degrees of upregulated glycolysis and expression of lipogenic genes. The reprogrammed metabolism of the E545K and H1047R p110α mutants was surprisingly not dependent on altered p110α lipid kinase activity.

scholarly journals Phosphoinositide 3-kinase-γ induces Xenopus oocyte maturation via lipid kinase activity

2001 ◽  
Vol 360 (3) ◽  
pp. 691 ◽  
Author(s):  
Solveig HEHL ◽  
Borislav STOYANOV ◽  
Wolf OEHRL ◽  
Roland SCHÖNHERR ◽  
Reinhard WETZKER ◽  
...  
Keyword(s):  
Oocyte Maturation ◽  
Xenopus Oocyte ◽  
Kinase Activity ◽  
Lipid Kinase ◽  
Phosphoinositide 3 Kinase

Phosphoinositide 3-kinase: the protein kinase that time forgot

2004 ◽  
Vol 32 (2) ◽  
pp. 330-331 ◽  
Author(s):  
L.C. Foukas ◽  
P.R. Shepherd
Keyword(s):  
Protein Kinase ◽  
Kinase Activity ◽  
Class I ◽  
Protein Kinase Activity ◽  
Lipid Kinase ◽  
Vast Amount ◽  
Lipid Kinases ◽  
Phosphoinositide 3 Kinase ◽  
In Cells

Class I phosphoinositide 3-kinases were originally characterized as lipid kinases, although more than 10 years ago they were also found to phosphorylate protein serine residues. However, while there is a vast amount of data on the function of this lipid kinase activity, relatively little is known about the function of the protein kinase activity. We discuss the evidence that suggests that the protein kinase activity of phosphoinositide 3-kinases mediates important signalling functions in cells.

scholarly journals Phosphoinositide 3 Kinase Mediates Toll-Like Receptor 4-Induced Activation of NF-κB in Endothelial Cells

2003 ◽  
Vol 71 (8) ◽  
pp. 4414-4420 ◽  
Author(s):  
Xianwu Li ◽  
Joan C. Tupper ◽  
Douglas D. Bannerman ◽  
Robert K. Winn ◽  
Christopher J. Rhodes ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Kinase Activity ◽  
Luciferase Activity ◽  
Pi3 Kinase ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Toll Like Receptor 4 ◽  
Kinase Activation ◽  
Phosphoinositide 3 Kinase ◽  
Negative Mutant

ABSTRACT Many of the proinflammatory effects of gram-negative bacteria are elicited by the interaction of bacterial lipopolysaccharide (LPS) with Toll-like receptor 4 (TLR4) expressed on host cells. TLR4 signaling leads to activation of NF-κB and transcription of many genes involved in the inflammatory response. In this study, we examined the signaling pathways involved in NF-κB activation by TLR4 signaling in human microvascular endothelial cells. Akt is a major downstream target of phosphoinositide 3 kinase (PI3-kinase), and PI3-kinase activation is necessary and sufficient for Akt phosphorylation. Consequently, Akt kinase activation was used as a measure of PI3-kinase activity. In a stable transfection system, dominant-negative mutants of myeloid differentiation factor 88 (MyD88) and interleukin-1 (IL-1) receptor-associated kinase 1 (IRAK-1) (MyD88-TIR and IRAK-DD, respectively) blocked Akt kinase activity in response to LPS and IL-1β. A dominant-negative mutant (Mal-P/H) of MyD88 adapter-like protein (Mal), a protein with homology to MyD88, failed to inhibit LPS- or IL-1β-induced Akt activity. Moreover, a dominant-negative mutant of p85 (p85-DN) inhibited the NF-κB luciferase activity, IL-6 production, and IκBα degradation elicited by LPS and IL-1β but not that stimulated by tumor necrosis factor alpha. The dominant-negative mutant of Akt partially inhibited the NF-κB luciferase activity evoked by LPS and IL-1β. However, expression of a constitutively activated Akt failed to induce NF-κB luciferase activity. These findings indicate that TLR4- and IL-1R-induced PI3-kinase activity is mediated by the adapter proteins MyD88 and IRAK-1 but not Mal. Further, these studies suggest that PI3-kinase is an important mediator of LPS and IL-1β signaling leading to NF-κB activation in endothelial cells and that Akt is necessary but not sufficient for NF-κB activation by TLR4.

scholarly journals PI3Kγ Mediates Microglial Proliferation and Cell Viability via ROS

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2534
Author(s):  
Caroline Schmidt ◽  
Nadine Schneble-Löhnert ◽  
Trim Lajqi ◽  
Reinhard Wetzker ◽  
Jörg P. Müller ◽  
...  
Keyword(s):  
Cell Viability ◽  
Kinase Activity ◽  
Regulatory Function ◽  
Ros Production ◽  
Wild Type ◽  
Lipid Kinase ◽  
Microglial Proliferation ◽  
Murine Microglia ◽  
Phosphoinositide 3 Kinase

(1) Background: Rapid microglial proliferation contributes to the complex responses of the innate immune system in the brain to various neuroinflammatory stimuli. Here, we investigated the regulatory function of phosphoinositide 3-kinase γ (PI3Kγ) and reactive oxygen species (ROS) for rapid proliferation of murine microglia induced by LPS and ATP. (2) Methods: PI3Kγ knockout mice (PI3Kγ KO), mice expressing catalytically inactive PI3Kγ (PI3Kγ KD) and wild-type mice were assessed for microglial proliferation using an in vivo wound healing assay. Additionally, primary microglia derived from newborn wild-type, PI3Kγ KO and PI3Kγ KD mice were used to analyze PI3Kγ effects on proliferation and cell viability, senescence and cellular and mitochondrial ROS production; the consequences of ROS production for proliferation and cell viability after LPS or ATP stimulation were studied using genetic and pharmacologic approaches. (3) Results: Mice with a loss of lipid kinase activity showed impaired proliferation of microglia. The prerequisite of induced microglial proliferation and cell viability appeared to be PI3Kγ-mediated induction of ROS production. (4) Conclusions: The lipid kinase activity of PI3Kγ plays a crucial role for microglial proliferation and cell viability after acute inflammatory activation.

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