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Gene Review

PIK3R1  -  phosphoinositide-3-kinase, regulatory...

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Disease relevance of PIK3R1

  • Escherichia coli expressed soybean PI3K phosphorylated phosphatidylinositol specifically at the D-3 position of the inositol ring to generate phosphatidylinositol 3-phosphate [1].
  • In BAEC, activation of eNOS by LPA is completely blocked by pertussis toxin, by the intracellular calcium chelator BAPTA (1,2-bis(aminophenoxy) ethane-N,N,N',N'-tetraacetic acid), and by the phosphoinositide 3-kinase (PI3-K) inhibitor wortmannin, but is unaffected by U0126, an inhibitor of mitogen-activated protein (MAP) kinase pathways [2].
  • However, activation of PI3K was not required for activation of ERK1/2, implying a parallel involvement of these pathways in the proliferative response of fibroblasts to hypoxia [3].
  • The phosphatidylinositol 3-kinase (PI3-K)/Akt pathway is involved in various malignancies, but the role of PI3-K/Akt pathway in Epstein-Barr virus (EBV) infected Burkitt's lymphoma (BL) cells remains unclear [4].

High impact information on PIK3R1

  • Vps34p shares significant sequence similarity with the catalytic subunit of bovine phosphatidylinositol (PI) 3-kinase [the 110-kilodalton (p110) subunit of PI 3-kinase], which is known to interact with activated cell surface receptor tyrosine kinases [5].
  • The angiogenic program is regulated by extracellular factors, whose input is integrated at least in part at the level of signal transduction pathways driven by phosphoinositide 3 kinase (PI3K) and phospholipase Cgamma (PLCgamma) [6].
  • The underlying mechanism by which PLCgamma antagonized tube formation appeared to be by competing with PI3K for their common substrate, phosphatidylinositol-4,5-bisphosphate [6].
  • The RAS-independent activation of MAP kinase by LPA was blocked by inhibitors of phosphatidylinositol 3-kinase (PI3K) or by overexpression of a dominant-negative mutant of the gamma isoform of PI3K [7].
  • We report the cloning and characterization of soybean PI3K cDNAs and present evidence for the induction of a distinctive form of this enzyme specific to nodule organogenesis [1].

Chemical compound and disease context of PIK3R1

  • Because lysophosphatidic acid (LPA) has been proposed to be responsible for this activity of PCM and is known to activate the G(i) protein, inhibitors of the G protein pertussis toxin and of the associated phosphatidylinositol 3-kinase (PI3K) wortmannin were used [8].

Biological context of PIK3R1

  • Inhibitors of PPARalpha, PI3 kinase and MAPK, respectively, markedly attenuate bezafibrate-induced upregulation of eNOS [9].
  • Thus, with impaired PI 3-kinase signaling and intact MAPK signaling, as seen in insulin resistance, insulin may lose its ability to maintain VSMC quiescence and instead promote VSMC migration [10].
  • The interactions of the N-terminal src homology (SH2) domain (N-SH2) of the 85 kDa subunit of phosphatidylinositol 3'-kinase (PI-3K) with phosphotyrosine (ptyr) and a series of ptyr-containing peptides have been examined by NMR spectroscopy [11].
  • Shear stress increased Cbl phosphorylation to 2.9-fold of control and Cbl association with the regulatory PI-3 kinase subunit p85 to 5.4-fold [12].
  • Pretreatment with either the MEK1 inhibitor U0126 or PI3-kinase inhibitor LY294002 sensitized BAE cells to TNF-induced apoptosis [13].

Anatomical context of PIK3R1

  • Fluid shear stress can activate PI-3 kinase and JNK in vascular endothelial cells [12].
  • Our results suggest that Cbl plays a critical role in the shear stress induction of PI 3-kinase and JNK activities, and that this shear-induced activation requires the interaction of endothelial integrins with extracellular matrix proteins [12].
  • By using both pharmacologic and genetic approaches, we found that in addition to ERK1/2, phosphatidylinositol 3-kinase (PI3K), Akt, mammalian target of rapamycin (mTOR), and p70 S6K-dependent signaling pathways are required for ATP-induced proliferation of adventitial fibroblasts [14].
  • RESULTS: PI-3K activity was found in both lens epithelial cells and fiber cells [15].
  • Here, we show that infected B lymphocytes display constitutive phosphoinositide 3-kinase (PI3-K) activity, which appears to be necessary for proliferation, but not survival [16].

Associations of PIK3R1 with chemical compounds

  • In order to establish which of the IGF-I signaling pathways contributed to anti-TGF-beta(1) and anti-apoptotic effects, the inhibitors of PI3-kinase - (LY 294002) and MEK- (MAPKK for ERK) (PD 098059) mediated signaling pathways were applied to our model [17].
  • ERK1/2 seemed necessary for NO* production early (<5 min) after H(2)O(2) addition, whereas PI 3-kinase/Akt was more important at later time points [18].
  • Recently, insulin-like growth factor-1 (IGF-1) was shown to enhance retinal endothelial glucose transport in a process that is dependent on protein kinase C (PKC) and phosphatidylinositol-3 kinase (PI3 kinase) [19].
  • LktA-induced TP of the CD18 tail was attenuated by an NRTK inhibitor, herbimycin A; a phosphatidylinositol 3'-kinase (PI 3-kinase) inhibitor, wortmannin; and a Src kinase inhibitor, PP2, in a concentration-dependent manner [20].
  • We found that the PI 3-kinase heterodimer consisting of the regulatory and catalytic subunits was associated essentially with the subplasmalemmal cytoskeleton in both resting and nicotine-stimulated chromaffin cells [21].

Analytical, diagnostic and therapeutic context of PIK3R1

  • PI-3K activity in capsule-epithelium and fiber cell layers was determined after immunoprecipitation with antibodies against p85, the regulatory subunit of PI-3K [15].
  • The amount of PI 3-kinase in membrane and cytosol fractions was determined by densitometry of immunoblots [22].


  1. A phosphatidylinositol 3-kinase is induced during soybean nodule organogenesis and is associated with membrane proliferation. Hong, Z., Verma, D.P. Proc. Natl. Acad. Sci. U.S.A. (1994) [Pubmed]
  2. Lysophosphatidic acid and receptor-mediated activation of endothelial nitric-oxide synthase. Kou, R., Igarashi, J., Michel, T. Biochemistry (2002) [Pubmed]
  3. Activation of phosphatidylinositol 3-kinase, Akt, and mammalian target of rapamycin is necessary for hypoxia-induced pulmonary artery adventitial fibroblast proliferation. Gerasimovskaya, E.V., Tucker, D.A., Stenmark, K.R. J. Appl. Physiol. (2005) [Pubmed]
  4. Functional role of phosphatidylinositol 3-kinase/Akt pathway on cell growth and lytic cycle of Epstein-Barr virus in the Burkitt's lymphoma cell line, P3HR-1. Mori, T., Sairenji, T. Virus Genes (2006) [Pubmed]
  5. Phosphatidylinositol 3-kinase encoded by yeast VPS34 gene essential for protein sorting. Schu, P.V., Takegawa, K., Fry, M.J., Stack, J.H., Waterfield, M.D., Emr, S.D. Science (1993) [Pubmed]
  6. Regulating angiogenesis at the level of PtdIns-4,5-P2. Im, E., Kazlauskas, A. EMBO J. (2006) [Pubmed]
  7. PI 3-kinase gamma and protein kinase C-zeta mediate RAS-independent activation of MAP kinase by a Gi protein-coupled receptor. Takeda, H., Matozaki, T., Takada, T., Noguchi, T., Yamao, T., Tsuda, M., Ochi, F., Fukunaga, K., Inagaki, K., Kasuga, M. EMBO J. (1999) [Pubmed]
  8. Platelet-conditioned medium increases endothelial electrical resistance independently of cAMP/PKA and cGMP/PKG. Gainor, J.P., Morton, C.A., Roberts, J.T., Vincent, P.A., Minnear, F.L. Am. J. Physiol. Heart Circ. Physiol. (2001) [Pubmed]
  9. Effects of bezafibrate on the expression of endothelial nitric oxide synthase gene and its mechanisms in cultured bovine endothelial cells. Wang, Y., Wang, Y., Yang, Q., Yan, J.T., Zhao, C., Cianflone, K., Wang, D.W. Atherosclerosis (2006) [Pubmed]
  10. Insulin affects vascular smooth muscle cell phenotype and migration via distinct signaling pathways. Wang, C.C., Gurevich, I., Draznin, B. Diabetes (2003) [Pubmed]
  11. NMR analysis of interactions of a phosphatidylinositol 3'-kinase SH2 domain with phosphotyrosine peptides reveals interdependence of major binding sites. Günther, U.L., Liu, Y., Sanford, D., Bachovchin, W.W., Schaffhausen, B. Biochemistry (1996) [Pubmed]
  12. Role of Cbl in shear-activation of PI 3-kinase and JNK in endothelial cells. Miao, H., Yuan, S., Wang, Y., Tsygankov, A., Chien, S. Biochem. Biophys. Res. Commun. (2002) [Pubmed]
  13. Inhibition of phosphatidylinositol-3 kinase/Akt or mitogen-activated protein kinase signaling sensitizes endothelial cells to TNF-alpha cytotoxicity. Zhang, L., Himi, T., Morita, I., Murota, S. Cell Death Differ. (2001) [Pubmed]
  14. Extracellular ATP-induced proliferation of adventitial fibroblasts requires phosphoinositide 3-kinase, Akt, mammalian target of rapamycin, and p70 S6 kinase signaling pathways. Gerasimovskaya, E.V., Tucker, D.A., Weiser-Evans, M., Wenzlau, J.M., Klemm, D.J., Banks, M., Stenmark, K.R. J. Biol. Chem. (2005) [Pubmed]
  15. Phosphatidylinositol 3-kinase in bovine lens and its stimulation by insulin and IGF-1. Chandrasekher, G., Bazan, H.E. Invest. Ophthalmol. Vis. Sci. (2000) [Pubmed]
  16. Constitutive PI3-K activity is essential for proliferation, but not survival, of Theileria parva-transformed B cells. Baumgartner, M., Chaussepied, M., Moreau, M.F., Werling, D., Davis, W.C., Garcia, A., Langsley, G. Cell. Microbiol. (2000) [Pubmed]
  17. Dissimilar effects of LY 294002 and PD 098059 in IGF-I-mediated inhibition of TGF-beta(1) expression and apoptosis in bovine mammary epithelial cells. Zarzyńska, J., Motyl, T. J. Physiol. Pharmacol. (2005) [Pubmed]
  18. Akt-dependent phosphorylation of serine 1179 and mitogen-activated protein kinase kinase/extracellular signal-regulated kinase 1/2 cooperatively mediate activation of the endothelial nitric-oxide synthase by hydrogen peroxide. Cai, H., Li, Z., Davis, M.E., Kanner, W., Harrison, D.G., Dudley, S.C. Mol. Pharmacol. (2003) [Pubmed]
  19. Insulin-like growth factor-1 effects on bovine retinal endothelial cell glucose transport: role of MAP kinase. DeBosch, B.J., Deo, B.K., Kumagai, A.K. J. Neurochem. (2002) [Pubmed]
  20. Mannheimia haemolytica leukotoxin activates a nonreceptor tyrosine kinase signaling cascade in bovine leukocytes, which induces biological effects. Jeyaseelan, S., Kannan, M.S., Briggs, R.E., Thumbikat, P., Maheswaran, S.K. Infect. Immun. (2001) [Pubmed]
  21. Possible involvement of phosphatidylinositol 3-kinase in regulated exocytosis: studies in chromaffin cells with inhibitor LY294002. Chasserot-Golaz, S., Hubert, P., Thiersé, D., Dirrig, S., Vlahos, C.J., Aunis, D., Bader, M.F. J. Neurochem. (1998) [Pubmed]
  22. Phosphatidylinositol 3-kinase in bovine photoreceptor rod outer segments. Guo, X., Ghalayini, A.J., Chen, H., Anderson, R.E. Invest. Ophthalmol. Vis. Sci. (1997) [Pubmed]
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