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Your search keyword '"Gassama-Diagne A"' showing total 6 results
Start Over Author "Gassama-Diagne A" Journal molecular biology of the cell
6 results on '"Gassama-Diagne A"'

1. The Phosphoinositol-3-Kinase–Protein Kinase B/Akt Pathway Is Critical forPseudomonas aeruginosaStrain PAK Internalization

Author

Joanne N. Engel, Keith E. Mostov, Arlinet Kierbel, and Ama Gassama-Diagne

Subjects
media_common.quotation_subject, macromolecular substances, Protein Serine-Threonine Kinases, Biology, Cell Line, Wortmannin, Phosphatidylinositol 3-Kinases, chemistry.chemical_compound, Dogs, Phosphatidylinositol Phosphates, Proto-Oncogene Proteins, Animals, Humans, LY294002, Phosphatidylinositol, RNA, Small Interfering, Internalization, Molecular Biology, Protein kinase B, PI3K/AKT/mTOR pathway, media_common, Kinase, Epithelial Cells, Articles, Cell Biology, Molecular biology, Cell biology, Enzyme Activation, chemistry, Pseudomonas aeruginosa, Signal transduction, Proto-Oncogene Proteins c-akt, HeLa Cells, Signal Transduction
Abstract

Several Pseudomonas aeruginosa strains are internalized by epithelial cells in vitro and in vivo, but the host pathways usurped by the bacteria to enter nonphagocytic cells are not clearly understood. Here, we report that internalization of strain PAK into epithelial cells triggers and requires activation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B/Akt (Akt). Incubation of Madin-Darby canine kidney (MDCK) or HeLa cells with the PI3K inhibitors LY294002 (LY) or wortmannin abrogated PAK uptake. Addition of the PI3K product phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] to polarized MDCK cells was sufficient to increase PAK internalization. PtdIns(3,4,5)P3accumulated at the site of bacterial binding in an LY-dependent manner. Akt phosphorylation correlated with PAK invasion. The specific Akt phosphorylation inhibitor SH-5 inhibited PAK uptake; internalization also was inhibited by small interfering RNA-mediated depletion of Akt phosphorylation. Expression of constitutively active Akt was sufficient to restore invasion when PI3K signaling was inhibited. Together, these results demonstrate that the PI3K signaling pathway is necessary and sufficient for the P. aeruginosa entry and provide the first example of a bacterium that requires Akt for uptake into epithelial cells.

Published
2005

2. SHIP2 regulates epithelial cell polarity through its lipid product, which binds to Dlg1, a pathway subverted by hepatitis C virus core protein

Author

Ronan Barre, Clotilde Cariven, Aline Awad, Jean Pierre Salles, Christophe Erneux, Didier Samuel, Mickaël Marin, Sokhavuth Sar, and Ama Gassama-Diagne

Subjects
Phosphatidylinositol 4,5-Diphosphate, RHOA, Hepacivirus, Viral Core Proteins -- genetics -- metabolism, Discs Large Homolog 1 Protein, chemistry.chemical_compound, Phosphatidylinositol 3-Kinases, Phosphatidylinositol Phosphates, Adaptor Proteins, Signal Transducing -- genetics -- metabolism, Cell polarity, Phosphatidylinositol 4,5-Diphosphate -- metabolism, Protein Isoforms, RNA, Small Interfering, Hepacivirus -- physiology, Epithelial polarity, Kinase, Viral Core Proteins, Cell Polarity, Articles, Sciences bio-médicales et agricoles, Cell biology, Phosphatidylinositol Phosphates -- metabolism, Cell Biology of Disease, Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases, Host-Pathogen Interactions, Epithelial Cells -- metabolism -- virology, Hepatocytes -- metabolism -- virology, RNA, Small Interfering -- genetics -- metabolism, Sciences exactes et naturelles, Signal Transduction, Polarity (physics), RAC1, Biology, Sciences de l'ingénieur, Cell Line, Dogs, Animals, Humans, Phosphatidylinositol, Molecular Biology, Adaptor Proteins, Signal Transducing, Phosphoric Monoester Hydrolases -- antagonists & inhibitors -- genetics -- metabolism, Phosphatidylinositol 3-Kinases -- genetics -- metabolism, Membrane Proteins, Lipid metabolism, Généralités, Epithelial Cells, Cell Biology, Molecular biology, Phosphoric Monoester Hydrolases, chemistry, Gene Expression Regulation, Membrane Proteins -- genetics -- metabolism, biology.protein, Hepatocytes, Protein Isoforms -- antagonists & inhibitors -- genetics -- metabolism
Abstract

The main targets of hepatitis C virus (HCV) are hepatocytes, the highly polarized cells of the liver, and all the steps of its life cycle are tightly dependent on host lipid metabolism. The interplay between polarity and lipid metabolism in HCV infection has been poorly investigated. Signaling lipids, such as phosphoinositides (PIs), play a vital role in polarity, which depends on the distribution and expression of PI kinases and PI phosphatases. In this study, we report that HCV core protein, expressed in Huh7 and Madin-Darby canine kidney (MDCK) cells, disrupts apicobasal polarity. This is associated with decreased expression of the polarity protein Dlg1 and the PI phosphatase SHIP2, which converts phosphatidylinositol 3,4,5-trisphosphate into phosphatidylinositol 4,5-bisphosphate (PtdIns(3,4)P2). SHIP2 is mainly localized at the basolateral membrane of polarized MDCK cells. In addition, PtdIns(3,4)P2 is able to bind to Dlg1. SHIP2 small interfering RNA or its catalytically dead mutant disrupts apicobasal polarity, similar to HCV core. In core-expressing cells, RhoA activity is inhibited, whereas Rac1 is activated. Of interest, SHIP2 expression rescues polarity, RhoA activation, and restricted core level in MDCK cells. We conclude that SHIP2 is an important regulator of polarity, which is subverted by HCV in epithelial cells. It is suggested that SHIP2 could be a promising target for anti-HCV treatment., Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2013

5. The Phosphoinositol-3-Kinase–Protein Kinase B/Akt Pathway Is Critical for Pseudomonas aeruginosaStrain PAK Internalization

Author

Kierbel, A., Gassama-Diagne, A., Mostov, K., and Engel, J. N.

Abstract

Several Pseudomonas aeruginosastrains are internalized by epithelial cells in vitro and in vivo, but the host pathways usurped by the bacteria to enter nonphagocytic cells are not clearly understood. Here, we report that internalization of strain PAK into epithelial cells triggers and requires activation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B/Akt (Akt). Incubation of Madin-Darby canine kidney (MDCK) or HeLa cells with the PI3K inhibitors LY294002 (LY) or wortmannin abrogated PAK uptake. Addition of the PI3K product phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] to polarized MDCK cells was sufficient to increase PAK internalization. PtdIns(3,4,5)P3accumulated at the site of bacterial binding in an LY-dependent manner. Akt phosphorylation correlated with PAK invasion. The specific Akt phosphorylation inhibitor SH-5 inhibited PAK uptake; internalization also was inhibited by small interfering RNA-mediated depletion of Akt phosphorylation. Expression of constitutively active Akt was sufficient to restore invasion when PI3K signaling was inhibited. Together, these results demonstrate that the PI3K signaling pathway is necessary and sufficient for the P. aeruginosaentry and provide the first example of a bacterium that requires Akt for uptake into epithelial cells.

Published
2005
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6. The phosphoinositol-3-kinase-protein kinase B/Akt pathway is critical for Pseudomonas aeruginosa strain PAK internalization.

Author

Kierbel A, Gassama-Diagne A, Mostov K, and Engel JN

Subjects
Animals, Cell Line, Dogs, Enzyme Activation, Epithelial Cells microbiology, HeLa Cells, Humans, Phosphatidylinositol Phosphates metabolism, Phosphatidylinositol Phosphates pharmacology, Protein Serine-Threonine Kinases antagonists & inhibitors, Protein Serine-Threonine Kinases genetics, Proto-Oncogene Proteins antagonists & inhibitors, Proto-Oncogene Proteins genetics, Proto-Oncogene Proteins c-akt, RNA, Small Interfering genetics, Signal Transduction, Phosphatidylinositol 3-Kinases metabolism, Protein Serine-Threonine Kinases metabolism, Proto-Oncogene Proteins metabolism, Pseudomonas aeruginosa metabolism, Pseudomonas aeruginosa pathogenicity
Abstract

Several Pseudomonas aeruginosa strains are internalized by epithelial cells in vitro and in vivo, but the host pathways usurped by the bacteria to enter nonphagocytic cells are not clearly understood. Here, we report that internalization of strain PAK into epithelial cells triggers and requires activation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B/Akt (Akt). Incubation of Madin-Darby canine kidney (MDCK) or HeLa cells with the PI3K inhibitors LY294002 (LY) or wortmannin abrogated PAK uptake. Addition of the PI3K product phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3] to polarized MDCK cells was sufficient to increase PAK internalization. PtdIns(3,4,5)P3 accumulated at the site of bacterial binding in an LY-dependent manner. Akt phosphorylation correlated with PAK invasion. The specific Akt phosphorylation inhibitor SH-5 inhibited PAK uptake; internalization also was inhibited by small interfering RNA-mediated depletion of Akt phosphorylation. Expression of constitutively active Akt was sufficient to restore invasion when PI3K signaling was inhibited. Together, these results demonstrate that the PI3K signaling pathway is necessary and sufficient for the P. aeruginosa entry and provide the first example of a bacterium that requires Akt for uptake into epithelial cells.

Published
2005
Full Text
View/download PDF

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