Faculty Opinions recommendation of Phosphatidylinositol 3-kinase-mediated effects of glucose on vacuolar H+-ATPase assembly, translocation, and acidification of intracellular compartments in renal epithelial cells.

2005 ◽  
Author(s):  
Sjur Olsnes
Keyword(s):  
Epithelial Cells ◽  
Phosphatidylinositol 3 Kinase ◽  
Renal Epithelial Cells ◽  
Mediated Effects ◽  
Intracellular Compartments ◽  
Phosphatidylinositol 3

scholarly journals Phosphatidylinositol 3-Kinase-Mediated Effects of Glucose on Vacuolar H+-ATPase Assembly, Translocation, and Acidification of Intracellular Compartments in Renal Epithelial Cells

2005 ◽  
Vol 25 (2) ◽  
pp. 575-589 ◽  
Author(s):  
Yuri Y. Sautin ◽  
Ming Lu ◽  
Andrew Gaugler ◽  
Li Zhang ◽  
Stephen L. Gluck
Keyword(s):  
Epithelial Cells ◽  
Apical Plasma Membrane ◽  
Proton Pumps ◽  
Coupling Mechanism ◽  
Phosphatidylinositol 3 Kinase ◽  
Ph Gradients ◽  
Renal Epithelial Cells ◽  
Pi3k Inhibitor Ly294002 ◽  
Intracellular Compartments ◽  
Phosphatidylinositol 3

ABSTRACT Vacuolar H+-ATPases (V-ATPases) are a family of ATP-driven proton pumps. They maintain pH gradients between intracellular compartments and are required for proton secretion out of the cytoplasm. Mechanisms of extrinsic control of V-ATPase are poorly understood. Previous studies showed that glucose is an important regulator of V-ATPase assembly in Saccharomyces cerevisiae. Human V-ATPase directly interacts with aldolase, providing a coupling mechanism for glucose metabolism and V-ATPase function. Here we show that glucose is a crucial regulator of V-ATPase in renal epithelial cells and that the effect of glucose is mediated by phosphatidylinositol 3-kinase (PI3K). Glucose stimulates V-ATPase-dependent acidification of the intracellular compartments in human proximal tubular cells HK-2 and porcine renal epithelial cells LLC-PK1. Glucose induces rapid ATP-independent assembly of the V1 and Vo domains of V-ATPase and extensive translocation of the V-ATPase V1 and Vo domains between different membrane pools and between membranes and the cytoplasm. In HK-2 cells, glucose stimulates polarized translocation of V-ATPase to the apical plasma membrane. The effects of glucose on V-ATPase trafficking and assembly can be abolished by pretreatment with the PI3K inhibitor LY294002 and can be reproduced in glucose-deprived cells by adenoviral expression of the constitutively active catalytic subunit p110α of PI3K. Taken together these data provide evidence that, in renal epithelial cells, glucose plays an important role in the control of V-ATPase-dependent acidification of intracellular compartments and V-ATPase assembly and trafficking and that the effects of glucose are mediated by PI3K-dependent signaling.

scholarly journals Induction of Monocyte Chemotactic Protein 1 in Colonic Epithelial Cells by Entamoeba histolytica Is Mediated via the Phosphatidylinositol 3-Kinase/p65 Pathway

2007 ◽  
Vol 75 (4) ◽  
pp. 1765-1770 ◽  
Author(s):  
Srinivas J. Kammanadiminti ◽  
Indranil Dey ◽  
Kris Chadee
Keyword(s):  
Epithelial Cells ◽  
Entamoeba Histolytica ◽  
Pi3 Kinase ◽  
Classical Pathway ◽  
Phosphatidylinositol 3 Kinase ◽  
Colonic Epithelial Cells ◽  
Monocyte Chemotactic Protein ◽  
Mrna Induction ◽  
Chemotactic Protein ◽  
Phosphatidylinositol 3

ABSTRACT The role intestinal epithelial cells play in the pathogenesis of amebic colitis is poorly understood. Herein, we demonstrate that secreted and soluble ameba (Entamoeba histolytica) proteins (SAP) induce expression of the chemoattractant monocyte chemotactic protein (MCP) in the colonic epithelial cell lines Caco-2, T84, and LS174T. MCP-1 mRNA induction was both dose and time dependent, with peak induction occurring at 8 h and with 100 μg/ml of SAP. Significant increase in MCP-1 protein expression was observed after 12 h. SAP failed to activate any of the mitogen-activated protein kinase pathways or IκB kinase activity. Moreover, inhibiting the classical pathway of NF-κB activation did not affect SAP-induced MCP-1 expression. Instead, we find that SAP-induced MCP-1 expression is dependent on posttranslational modification of the NFκB p65 subunit. SAP induced phosphorylation of p65 and enhanced NF-κB transcriptional activity, which are phosphatidylinositol 3-kinase (PI3 kinase) dependent. Treatment with PI3 kinase inhibitor LY290004 significantly abrogated the activation of Akt, p65, and MCP-1 mRNA induction. We conclude that colonic epithelial cells play a role in the initiation of inflammation by secreting chemokines in response to soluble ameba components.

Pneumococci induced TLR- and Rac1-dependent NF-κB-recruitment to the IL-8 promoter in lung epithelial cells

2006 ◽  
Vol 290 (4) ◽  
pp. L730-L737 ◽  
Author(s):  
Bernd Schmeck ◽  
Sylvia Huber ◽  
Kerstin Moog ◽  
Janine Zahlten ◽  
Andreas C. Hocke ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cell Activation ◽  
Rho Gtpase ◽  
Dominant Negative ◽  
Lung Epithelial Cells ◽  
Dominant Negative Mutant ◽  
Epithelial Cell Line ◽  
Phosphatidylinositol 3 Kinase ◽  
Lung Epithelial ◽  
Phosphatidylinositol 3

Streptococcus pneumoniae is the major pathogen of community-acquired pneumonia. The respiratory epithelium constitutes the first line of defense against invading lung pathogens, including pneumococci. We analyzed the involvement of Toll-like receptors (TLR) and Rho-GTPase signaling in the activation of human lung epithelial cells by pneumococci. S. pneumoniae induced release of interleukin-8 (IL-8) by human bronchial epithelial cell line BEAS-2B. Specific inhibition of Rac1 by Nsc23766 or a dominant-negative mutant of Rac1 strongly reduced cytokine release. In addition, pneumococci-related cell activation (IL-8 release, NF-κB-activation) depended on MyD88, phosphatidylinositol 3-kinase, and Cdc42 but not on RhoA. Pneumococci enhanced TLR1 and TLR2 mRNA expression in BEAS-2B cells, whereas TLR4 and TLR6 expression was constitutively high. TLR1 and 2 synergistically recognized pneumococci in cotransfection experiments. TLR4, TLR6, LPS-binding protein, and CD14 seem not to be involved in pneumococci-dependent cell activation. At the IL-8 gene promoter, recruitment of phosphorylated NF-κB subunit p65 was blocked by inhibition of Rac1, whereas binding of the phosphorylated activator protein-1 subunit c-Jun to the promoter was not diminished. In summary, these results suggest that S. pneumoniae activate human epithelial cells by TLR1/2 and a phosphatidylinositol 3-kinase- and Rac1-dependent NF-κB-recruitment to the IL-8 promoter.

Modulation of chloride secretory responses and barrier function of intestinal epithelial cells by theSalmonellaeffector protein SigD

2004 ◽  
Vol 287 (4) ◽  
pp. C939-C948 ◽  
Author(s):  
Lone S. Bertelsen ◽  
Günther Paesold ◽  
Sandra L. Marcus ◽  
Brett B. Finlay ◽  
Lars Eckmann ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Barrier Function ◽  
Egf Receptor ◽  
Inositol Phosphate ◽  
Chloride Secretion ◽  
Inhibitory Effect ◽  
Effector Protein ◽  
Phosphatidylinositol 3 Kinase ◽  
In Cells ◽  
Phosphatidylinositol 3

The Salmonella effector protein SigD is an inositol phosphate phosphatase that inhibits phosphatidylinositol 3-kinase-dependent signaling. Because epidermal growth factor (EGF) inhibits chloride secretion via phosphatidylinositol 3-kinase, we explored whether Salmonella infection might modify the inhibitory effect of EGF. As expected, EGF inhibited chloride secretion induced by carbachol in T84epithelial cells. Infection with wild-type (WT) but not sigD−mutant S. typhimurium SL1344 decreased CCh-stimulated chloride secretion. Moreover, WT but not sigD−Salmonella reduced the inhibitory effect of EGF on carbachol-stimulated chloride secretion. Complementation of sigD restored the ability of mutant Salmonella to reverse the inhibitory effect of EGF. EGF-induced EGF receptor phosphorylation was similar in cells infected with either WT or mutant Salmonella, and neither WT nor sigD−Salmonella altered recruitment of the p85 subunit of phosphatidylinositol 3-kinase to EGF receptor, implying that SigD acts downstream of these signaling events. Furthermore, transepithelial resistance fell more rapidly in cells infected with WT vs. sigD−Salmonella, indicating an early role for SigD in reducing barrier function, perhaps via activation of protein kinase C. We conclude that the Salmonella bacterial effector protein SigD may play critical roles in the pathogenesis of disease caused by this microorganism.

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