scholarly journals Ca2+-regulated Pool of Phosphatidylinositol-3-phosphate Produced by Phosphatidylinositol 3-Kinase C2α on Neurosecretory Vesicles

2008 ◽  
Vol 19 (12) ◽  
pp. 5593-5603 ◽  
Author(s):  
Peter J. Wen ◽  
Shona L. Osborne ◽  
Isabel C. Morrow ◽  
Robert G. Parton ◽  
Jan Domin ◽  
...  
Keyword(s):  
Critical Role ◽  
Neurosecretory Cells ◽  
Secretory Vesicles ◽  
Endosomal Trafficking ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Lipid Product ◽  
Phosphatidylinositol 3

Phosphatidylinositol-3-phosphate [PtdIns(3)P] is a key player in early endosomal trafficking and is mainly produced by class III phosphatidylinositol 3-kinase (PI3K). In neurosecretory cells, class II PI3K-C2α and its lipid product PtdIns(3)P have recently been shown to play a critical role during neuroexocytosis, suggesting that two distinct pools of PtdIns(3)P might coexist in these cells. However, the precise characterization of this additional pool of PtdIns(3)P remains to be established. Using a selective PtdIns(3)P probe, we have identified a novel PtdIns(3)P-positive pool localized on secretory vesicles, sensitive to PI3K-C2α knockdown and relatively resistant to wortmannin treatment. In neurosecretory cells, stimulation of exocytosis promoted a transient albeit large increase in PtdIns(3)P production localized on secretory vesicles sensitive to PI3K-C2α knockdown and expression of PI3K-C2α catalytically inactive mutant. Using purified chromaffin granules, we found that PtdIns(3)P production is controlled by Ca2+. We confirmed that PtdIns(3)P production from recombinantly expressed PI3K-C2α is indeed regulated by Ca2+. We provide evidence that a dynamic pool of PtdIns(3)P synthesized by PI3K-C2α occurs on secretory vesicles in neurosecretory cells, demonstrating that the activity of a member of the PI3K family is regulated by Ca2+ in vitro and in living neurosecretory cells.

scholarly journals A Crucial Role for the p110δ Subunit of Phosphatidylinositol 3-Kinase in B Cell Development and Activation

2002 ◽  
Vol 196 (6) ◽  
pp. 753-763 ◽  
Author(s):  
Elizabeth Clayton ◽  
Giuseppe Bardi ◽  
Sarah E. Bell ◽  
David Chantry ◽  
C. Peter Downes ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Critical Role ◽  
Cell Receptor ◽  
Calcium Flux ◽  
Phosphatidylinositol 3 Kinase ◽  
Marginal Zone B Cells ◽  
B Cell Homeostasis ◽  
Phosphatidylinositol 3

Mice lacking the p110δ catalytic subunit of phosphatidylinositol 3-kinase have reduced numbers of B1 and marginal zone B cells, reduced levels of serum immunoglobulins, respond poorly to immunization with type II thymus-independent antigen, and are defective in their primary and secondary responses to thymus-dependent antigen. p110δ−/− B cells proliferate poorly in response to B cell receptor (BCR) or CD40 signals in vitro, fail to activate protein kinase B, and are prone to apoptosis. p110δ function is required for BCR-mediated calcium flux, activation of phosphlipaseCγ2, and Bruton's tyrosine kinase. Thus, p110δ plays a critical role in B cell homeostasis and function.

Gallic acid promotes the in vitro development of sheep secondary isolated follicles involving the phosphatidylinositol 3-kinase pathway

2021 ◽  
pp. 106767
Author(s):  
Gizele A.L. Silva ◽  
Luana B. Araújo ◽  
Larissa C.R. Silva ◽  
Bruna B. Gouveia ◽  
Ricássio S. Barberino ◽  
...  
Keyword(s):  
Gallic Acid ◽  
Phosphatidylinositol 3 Kinase ◽  
In Vitro Development ◽  
Vitro Development ◽  
Kinase Pathway ◽  
Phosphatidylinositol 3

scholarly journals Characterization of VPS34-IN1, a selective inhibitor of Vps34, reveals that the phosphatidylinositol 3-phosphate-binding SGK3 protein kinase is a downstream target of class III phosphoinositide 3-kinase

2014 ◽  
Vol 463 (3) ◽  
pp. 413-427 ◽  
Author(s):  
Ruzica Bago ◽  
Nazma Malik ◽  
Michael J. Munson ◽  
Alan R. Prescott ◽  
Paul Davies ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Selective Inhibitor ◽  
Class Iii ◽  
Phosphate Binding ◽  
Downstream Target ◽  
Phosphoinositide 3 Kinase ◽  
Phosphatidylinositol 3

We characterize VPS34-IN, a potent and selective inhibitor of class III Vps34 PI3K. Using VPS34-IN1, we demonstrate that PtdIns(3)P, produced by Vps34 controls phosphorylation and activity of the SGK3 protein kinase.

scholarly journals In Vitro Antimetastatic Effect of Phosphatidylinositol 3-Kinase Inhibitor ZSTK474 on Prostate Cancer PC3 Cells

2013 ◽  
Vol 14 (7) ◽  
pp. 13577-13591 ◽  
Author(s):  
Wennan Zhao ◽  
Wenzhi Guo ◽  
Qianxiang Zhou ◽  
Sheng-Nan Ma ◽  
Ran Wang ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Kinase Inhibitor ◽  
Phosphatidylinositol 3 Kinase ◽  
Antimetastatic Effect ◽  
Pc3 Cells ◽  
Phosphatidylinositol 3

scholarly journals The Class II Phosphatidylinositol 3 kinase C2β Is Required for the Activation of the K+ Channel KCa3.1 and CD4 T-Cells

2009 ◽  
Vol 20 (17) ◽  
pp. 3783-3791 ◽  
Author(s):  
Shekhar Srivastava ◽  
Lie Di ◽  
Olga Zhdanova ◽  
Zhai Li ◽  
Santosha Vardhana ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Critical Role ◽  
Class Ii ◽  
K Channel ◽  
Channel Activity ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3

The Ca2+-activated K+ channel KCa3.1 is required for Ca2+ influx and the subsequent activation of T-cells. We previously showed that nucleoside diphosphate kinase beta (NDPK-B), a mammalian histidine kinase, directly phosphorylates and activates KCa3.1 and is required for the activation of human CD4 T lymphocytes. We now show that the class II phosphatidylinositol 3 kinase C2β (PI3K-C2β) is activated by the T-cell receptor (TCR) and functions upstream of NDPK-B to activate KCa3.1 channel activity. Decreased expression of PI3K-C2β by siRNA in human CD4 T-cells resulted in inhibition of KCa3.1 channel activity. The inhibition was due to decreased phosphatidylinositol 3-phosphate [PI(3)P] because dialyzing PI3K-C2β siRNA-treated T-cells with PI(3)P rescued KCa3.1 channel activity. Moreover, overexpression of PI3K-C2β in KCa3.1-transfected Jurkat T-cells led to increased TCR-stimulated activation of KCa3.1 and Ca2+ influx, whereas silencing of PI3K-C2β inhibited both responses. Using total internal reflection fluorescence microscopy and planar lipid bilayers, we found that PI3K-C2β colocalized with Zap70 and the TCR in peripheral microclusters in the immunological synapse. This is the first demonstration that a class II PI3K plays a critical role in T-cell activation.

scholarly journals Proteomic and biochemical comparison of the cellular interaction partners of human VPS33A and VPS33B

2017 ◽  
Author(s):  
Morag R. Hunter ◽  
Geoffrey G. Hesketh ◽  
Anne-Claude Gingras ◽  
Stephen C. Graham
Keyword(s):  
Sequence Similarity ◽  
Domain Architecture ◽  
Gel Filtration ◽  
Cellular Interaction ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Protein Subunit ◽  
Over Expression ◽  
Biochemical Comparison

ABSTRACTMulti-subunit tethering complexes control membrane fusion events in eukaryotic cells. CORVET and HOPS are two such multi-subunit tethering complexes, both containing the Sec1/Munc18 protein subunit VPS33A. Metazoans additionally possess VPS33B, which has considerable sequence similarity to VPS33A but does not integrate into CORVET or HOPS complexes and instead stably interacts with VIPAR. It has been recently suggested that VPS33B and VIPAR comprise two subunits of a novel multi-subunit tethering complex (named ‘CHEVI’), analogous in configuration to CORVET and HOPS. We utilised the BioID proximity biotinylation assay to compare and contrast the interactomes of VPS33A and VPS33B. Overall, few proteins were identified as associating with both VPS33A and VPS33B, suggesting these proteins have distinct sub-cellular localisations. Consistent with previous reports, we observed that VPS33A was co-localised with many components of class III phosphatidylinositol 3-kinase (PI3KC3) complexes: PIK3C3, PIK3R4, NRBF2, UVRAG and RUBICON. Although in this assay VPS33A clearly co-localised with several subunits of CORVET and HOPS, no proteins with the canonical CORVET/HOPS domain architecture were found to co-localise with VPS33B. Instead, we identified two novel VPS33B-interacting proteins, VPS53 and CCDC22. CCDC22 co-immunoprecipitated with VPS33B and VIPAR in over-expression conditions and interacts directly with the VPS33B-VIPAR complex in vitro. However, CCDC22 does not appear to co-fractionate with VPS33B and VIPAR in gel filtration of human cell lysates. We also observed that the protein complex in HEK293T cells which contained VPS33B and VIPAR was considerably smaller than CORVET/HOPS, suggesting that, unlike VPS33A, VPS33B does not assemble into a large stable multi-subunit tethering complex.

scholarly journals Tyrosine 1101 of Tie2 Is the Major Site of Association of p85 and Is Required for Activation of Phosphatidylinositol 3-Kinase and Akt

1998 ◽  
Vol 18 (7) ◽  
pp. 4131-4140 ◽  
Author(s):  
Christopher D. Kontos ◽  
Thomas P. Stauffer ◽  
Wen-Pin Yang ◽  
John D. York ◽  
Liwen Huang ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Vascular Development ◽  
Pi3 Kinase ◽  
Pleckstrin Homology Domain ◽  
Phosphatidylinositol 3 Kinase ◽  
Lipid Kinase ◽  
Embryonic Vascular Development ◽  
Phosphatidylinositol 3

ABSTRACT Tie2 is an endothelium-specific receptor tyrosine kinase that is required for both normal embryonic vascular development and tumor angiogenesis and is thought to play a role in vascular maintenance. However, the signaling pathways responsible for the function of Tie2 remain unknown. In this report, we demonstrate that the p85 subunit of phosphatidylinositol 3-kinase (PI3-kinase) associates with Tie2 and that this association confers functional lipid kinase activity. Mutation of tyrosine 1101 of Tie2 abrogated p85 association both in vitro and in vivo in yeast. Tie2 was found to activate PI3-kinase in vivo as demonstrated by direct measurement of increases in cellular phosphatidylinositol 3-phosphate and phosphatidylinositol 3,4-bisphosphate, by plasma membrane translocation of a green fluorescent protein-Akt pleckstrin homology domain fusion protein, and by downstream activation of the Akt kinase. Activation of PI3-kinase was abrogated in these assays by mutation of Y1101 to phenylalanine, consistent with a requirement for this residue for p85 association with Tie2. These results suggest that activation of PI3-kinase and Akt may in part account for Tie2’s role in both embryonic vascular development and pathologic angiogenesis, and they are consistent with a role for Tie2 in endothelial cell survival.

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