α-Thrombin-mediated Phosphatidylinositol 3-Kinase Activation through Release of Gβγ Dimers from Gαq and Gα i2

Reema Goel, Polly J. Phillips-Mason, Alice Gardner, Daniel M. Raben, Joseph J. Baldassare

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Chinese hamster embryonic fibroblasts (IIC9 cells) express the G α subunits Gαs, Gαi2, Gαi3, Gαo, Gαq/11, and Gα13. Consistent with reports in other cell types, α-thrombin stimulates a subset of the expressed G proteins in IIC9 cells, namely Gi2, G13, and Gq as measured by an in vitro membrane [35S]guanosine 5′-O-(3-thio)triphosphate binding assay. Using specific Gα peptides, which block coupling of G-protein receptors to selective G proteins, as well as dominant negative xanthine nucleotide-binding Gα mutants, we show that activation of the phosphatidylinositol 3-kinase/Akt pathway is dependent on Gq and Gi2. To examine the role of the two G proteins, we examined the events upstream of PI 3-kinase. The activation of the PI 3-kinase/Akt pathway by a-thrombin in IIC9 cells is blocked by the expression of dominant negative Ras and β-arrestin1 (Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2000) J. Biol. Chem. 275, 18046-18053, and Goel, R., Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2002) J. Biol. Chem. 277, 18640-18648), indicating a role for Ras and β-arrestin1. Interestingly, inhibition of Gi2 and Gq activation blocks Ras activation and β-arrestin1 membrane translocation, respectively. Furthermore, expression of the Gβγ sequestrant, α-transducin, inhibits both Ras activation and membrane translocation of β-arrestin1, suggesting that Gβγ dimers from Gαi2 and Gαq activate different effectors to coordinately regulate the PI 3-kinase/Akt pathway.

Original languageEnglish (US)
Pages (from-to)6701-6710
Number of pages10
JournalJournal of Biological Chemistry
Volume279
Issue number8
DOIs
StatePublished - Feb 20 2004

Fingerprint

Phosphatidylinositol 3-Kinase
GTP-Binding Proteins
Thrombin
Dimers
Chemical activation
Phosphatidylinositol 3-Kinases
Membranes
Transducin
Guanosine 5'-O-(3-Thiotriphosphate)
Gastrin-Secreting Cells
Xanthine
Cricetulus
Fibroblasts
Nucleotides
Assays
Peptides

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Goel, Reema ; Phillips-Mason, Polly J. ; Gardner, Alice ; Raben, Daniel M. ; Baldassare, Joseph J. / α-Thrombin-mediated Phosphatidylinositol 3-Kinase Activation through Release of Gβγ Dimers from Gαq and Gα i2 In: Journal of Biological Chemistry. 2004 ; Vol. 279, No. 8. pp. 6701-6710.
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abstract = "Chinese hamster embryonic fibroblasts (IIC9 cells) express the G α subunits Gαs, Gαi2, Gαi3, Gαo, Gαq/11, and Gα13. Consistent with reports in other cell types, α-thrombin stimulates a subset of the expressed G proteins in IIC9 cells, namely Gi2, G13, and Gq as measured by an in vitro membrane [35S]guanosine 5′-O-(3-thio)triphosphate binding assay. Using specific Gα peptides, which block coupling of G-protein receptors to selective G proteins, as well as dominant negative xanthine nucleotide-binding Gα mutants, we show that activation of the phosphatidylinositol 3-kinase/Akt pathway is dependent on Gq and Gi2. To examine the role of the two G proteins, we examined the events upstream of PI 3-kinase. The activation of the PI 3-kinase/Akt pathway by a-thrombin in IIC9 cells is blocked by the expression of dominant negative Ras and β-arrestin1 (Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2000) J. Biol. Chem. 275, 18046-18053, and Goel, R., Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2002) J. Biol. Chem. 277, 18640-18648), indicating a role for Ras and β-arrestin1. Interestingly, inhibition of Gi2 and Gq activation blocks Ras activation and β-arrestin1 membrane translocation, respectively. Furthermore, expression of the Gβγ sequestrant, α-transducin, inhibits both Ras activation and membrane translocation of β-arrestin1, suggesting that Gβγ dimers from Gαi2 and Gαq activate different effectors to coordinately regulate the PI 3-kinase/Akt pathway.",
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α-Thrombin-mediated Phosphatidylinositol 3-Kinase Activation through Release of Gβγ Dimers from Gαq and Gα i2 . / Goel, Reema; Phillips-Mason, Polly J.; Gardner, Alice; Raben, Daniel M.; Baldassare, Joseph J.

In: Journal of Biological Chemistry, Vol. 279, No. 8, 20.02.2004, p. 6701-6710.

Research output: Contribution to journalArticle

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T1 - α-Thrombin-mediated Phosphatidylinositol 3-Kinase Activation through Release of Gβγ Dimers from Gαq and Gα i2

AU - Goel, Reema

AU - Phillips-Mason, Polly J.

AU - Gardner, Alice

AU - Raben, Daniel M.

AU - Baldassare, Joseph J.

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N2 - Chinese hamster embryonic fibroblasts (IIC9 cells) express the G α subunits Gαs, Gαi2, Gαi3, Gαo, Gαq/11, and Gα13. Consistent with reports in other cell types, α-thrombin stimulates a subset of the expressed G proteins in IIC9 cells, namely Gi2, G13, and Gq as measured by an in vitro membrane [35S]guanosine 5′-O-(3-thio)triphosphate binding assay. Using specific Gα peptides, which block coupling of G-protein receptors to selective G proteins, as well as dominant negative xanthine nucleotide-binding Gα mutants, we show that activation of the phosphatidylinositol 3-kinase/Akt pathway is dependent on Gq and Gi2. To examine the role of the two G proteins, we examined the events upstream of PI 3-kinase. The activation of the PI 3-kinase/Akt pathway by a-thrombin in IIC9 cells is blocked by the expression of dominant negative Ras and β-arrestin1 (Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2000) J. Biol. Chem. 275, 18046-18053, and Goel, R., Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2002) J. Biol. Chem. 277, 18640-18648), indicating a role for Ras and β-arrestin1. Interestingly, inhibition of Gi2 and Gq activation blocks Ras activation and β-arrestin1 membrane translocation, respectively. Furthermore, expression of the Gβγ sequestrant, α-transducin, inhibits both Ras activation and membrane translocation of β-arrestin1, suggesting that Gβγ dimers from Gαi2 and Gαq activate different effectors to coordinately regulate the PI 3-kinase/Akt pathway.

AB - Chinese hamster embryonic fibroblasts (IIC9 cells) express the G α subunits Gαs, Gαi2, Gαi3, Gαo, Gαq/11, and Gα13. Consistent with reports in other cell types, α-thrombin stimulates a subset of the expressed G proteins in IIC9 cells, namely Gi2, G13, and Gq as measured by an in vitro membrane [35S]guanosine 5′-O-(3-thio)triphosphate binding assay. Using specific Gα peptides, which block coupling of G-protein receptors to selective G proteins, as well as dominant negative xanthine nucleotide-binding Gα mutants, we show that activation of the phosphatidylinositol 3-kinase/Akt pathway is dependent on Gq and Gi2. To examine the role of the two G proteins, we examined the events upstream of PI 3-kinase. The activation of the PI 3-kinase/Akt pathway by a-thrombin in IIC9 cells is blocked by the expression of dominant negative Ras and β-arrestin1 (Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2000) J. Biol. Chem. 275, 18046-18053, and Goel, R., Phillips-Mason, P. J., Raben, D. M., and Baldassare, J. J. (2002) J. Biol. Chem. 277, 18640-18648), indicating a role for Ras and β-arrestin1. Interestingly, inhibition of Gi2 and Gq activation blocks Ras activation and β-arrestin1 membrane translocation, respectively. Furthermore, expression of the Gβγ sequestrant, α-transducin, inhibits both Ras activation and membrane translocation of β-arrestin1, suggesting that Gβγ dimers from Gαi2 and Gαq activate different effectors to coordinately regulate the PI 3-kinase/Akt pathway.

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