scholarly journals The p110αand p110βIsoforms of Class I Phosphatidylinositol 3-Kinase Are Involved in Toll-Like Receptor 5 Signaling in Epithelial Cells

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Sabine M. Ivison ◽  
Mohammed A. S. Khan ◽  
Nicholas R. Graham ◽  
Leila A. Shobab ◽  
Yu Yao ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
P38 Map Kinase ◽  
Carcinoma Cells ◽  
Model Systems ◽  
Toll Like Receptor ◽  
Phosphatidylinositol 3 Kinase ◽  
Proinflammatory Response ◽  
Colon Carcinoma Cells ◽  
Toll Like Receptor 5 ◽  
Phosphatidylinositol 3

Background. Bacterial flagellin triggers inflammation in mammalian cells via Toll-like receptor (TLR) 5. Release of the chemokine IL-8 in response to flagellin involves NF-κB, p38 MAP kinase, and phosphatidylinositol 3-kinase (PI3K). However, PI3K has been reported to be either pro- or anti-inflammatory in different model systems. We hypothesized that this could be due to different activities of the p110αandβisoforms of PI3K.Results. PI3K and Akt were rapidly activated in Caco-2 colon carcinoma cells by flagellin. Using a plasmid-based shRNA delivery system and novel p110 isoform-specific inhibitors, we found that flagellin-induced IL-8 production was dependent on both p110αand p110β. However in the mouse, inhibition of p110βbut not p110αreduced the increase of serum IL-6 levels induced by intraperitoneal injection of flagellin.Conclusions. These data demonstrate that the p110αandβisoforms of class IA PI3K are both required for the proinflammatory response to flagellin.

scholarly journals cAMP-stimulated Na+ transport in H441 distal lung epithelial cells: role of PKA, phosphatidylinositol 3-kinase, and sgk1

2004 ◽  
Vol 287 (4) ◽  
pp. L843-L851 ◽  
Author(s):  
Christie P. Thomas ◽  
Jason R. Campbell ◽  
Patrick J. Wright ◽  
Russell F. Husted
Keyword(s):  
Apical Cell ◽  
P38 Map Kinase ◽  
Lung Epithelial Cells ◽  
Epithelial Cell Line ◽  
Phosphatidylinositol 3 Kinase ◽  
Transport Pathway ◽  
Early Effect ◽  
Sustained Effect ◽  
Phosphatidylinositol 3

H441 cells, a bronchiolar epithelial cell line, develop a cAMP-regulated benzamil-sensitive Na+ transport pathway on permeable supports (Itani OA, Auerbach SD, Husted RF, Volk KA, Ageloff S, Knepper MA, Stokes JB, Thomas CP. Am J Physiol Lung Cell Mol Physiol 282: L631–L641, 2002). To understand the molecular basis for the stimulation of Na+ transport, we delineated the role of specific intracellular pathways and examined the effect of cAMP on αβγ-epithelial Na+ channel (ENaC) and sgk1 expression. Na+ transport increases within 5 min of cAMP stimulation and is sustained for >24 h. The sustained effect of cAMP on Na+ transport is abolished by LY-294002, an inhibitor of phosphatidylinositol 3-kinase, by H89, an inhibitor of PKA, or by SB-202190, an inhibitor of p38 MAP kinase. The sustained effect of cAMP was associated with increases in α-ENaC mRNA and protein but without a detectable increase in βγ-ENaC and sgk1. The early effect of cAMP on Na+ transport is brefeldin sensitive and is mediated via PKA. These results are consistent with a model where the early effect of cAMP is to increase trafficking of Na+ channels to the apical cell surface whereas the sustained effect requires the synthesis of α-ENaC.

Schizosaccharomyces pombe Vps34p, a phosphatidylinositol-specific PI 3-kinase essential for normal cell growth and vacuole morphology

1995 ◽  
Vol 108 (12) ◽  
pp. 3745-3756 ◽  
Author(s):  
K. Takegawa ◽  
D.B. DeWald ◽  
S.D. Emr
Keyword(s):  
Amino Acid ◽  
Schizosaccharomyces Pombe ◽  
Mammalian Cells ◽  
Membrane Fraction ◽  
Kinase Activity ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Phosphatidylinositol 3 Kinase ◽  
Acid Protein ◽  
Phosphatidylinositol 3

We have cloned the gene, vps34+, from the fission yeast Schizosaccharomyces pombe which encodes an 801 amino acid protein with phosphatidylinositol 3-kinase activity. The S. pombe Vps34 protein shares 43% amino acid sequence identity with the Saccharomyces cerevisiae Vps34 protein and 28% identity with the p110 catalytic subunit of the mammalian phosphatidylinositol 3-kinase. When the vps34+ gene is disrupted, S.pombe strains are temperature-sensitive for growth and the mutant cells contain enlarged vacuoles. Furthermore, while wild-type strains exhibit substantial levels of phosphatidylinositol 3-kinase activity, this activity is not detected in the vps34 delta strain. S.pombe Vps34p-specific antiserum detects a single protein in cells of -90 kDa that fractionates almost exclusively with the crude membrane fraction. Phosphatidylinositol 3-kinase activity also is localized mainly in the membrane fraction of wild-type cells. Immunoisolated Vps34p specifically phosphorylates phosphatidylinositol on the D-3 position of the inositol ring to yield phosphatidylinositol(3)phosphate. but does not utilize phosphatidylinositol(4)phosphate or phosphatidylinositol(4,5)bisphosphate as substrates. In addition, when compared to the mammalian p110 phosphatidylinositol 3-kinase, S. pombe Vps34p is relatively insensitive to the inhibitors wortmannin and LY294002. Together, these results indicate that S. pombe Vps34 is more similar to the phosphatidylinositol-specific 3-kinase, Vps34p from S. cerevisiae, and is distinct from the p110/p85 and G protein-coupled phosphatidylinositol 3-kinases from mammalian cells. These data are discussed in relation to the possible role of Vps34p in vesicle-mediated protein sorting to the S. pombe vacuole.

scholarly journals Beclin 1 Forms Two Distinct Phosphatidylinositol 3-Kinase Complexes with Mammalian Atg14 and UVRAG

2008 ◽  
Vol 19 (12) ◽  
pp. 5360-5372 ◽  
Author(s):  
Eisuke Itakura ◽  
Chieko Kishi ◽  
Kinji Inoue ◽  
Noboru Mizushima
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Coiled Coil ◽  
Pi3 Kinase ◽  
Beclin 1 ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Interacting Protein ◽  
Vacuolar Protein ◽  
Phosphatidylinositol 3

Class III phosphatidylinositol 3-kinase (PI3-kinase) regulates multiple membrane trafficking. In yeast, two distinct PI3-kinase complexes are known: complex I (Vps34, Vps15, Vps30/Atg6, and Atg14) is involved in autophagy, and complex II (Vps34, Vps15, Vps30/Atg6, and Vps38) functions in the vacuolar protein sorting pathway. Atg14 and Vps38 are important in inducing both complexes to exert distinct functions. In mammals, the counterparts of Vps34, Vps15, and Vps30/Atg6 have been identified as Vps34, p150, and Beclin 1, respectively. However, orthologues of Atg14 and Vps38 remain unknown. We identified putative mammalian homologues of Atg14 and Vps38. The Vps38 candidate is identical to UV irradiation resistance-associated gene (UVRAG), which has been reported as a Beclin 1-interacting protein. Although both human Atg14 and UVRAG interact with Beclin 1 and Vps34, Atg14, and UVRAG are not present in the same complex. Although Atg14 is present on autophagic isolation membranes, UVRAG primarily associates with Rab9-positive endosomes. Silencing of human Atg14 in HeLa cells suppresses autophagosome formation. The coiled-coil region of Atg14 required for binding with Vps34 and Beclin 1 is essential for autophagy. These results suggest that mammalian cells have at least two distinct class III PI3-kinase complexes, which may function in different membrane trafficking pathways.

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