title: Inhibition of the phosphatidylinositol-3-kinase pathway abrogates polyinosinic:polycytidylic acid-stimulated hyaluronan-mediated human mucosal smooth muscle cell binding of U937 monocytic cells.
abstract: The origin of inflammatory bowel disease (IBD) is unknown and likely to be multifactorial. Our laboratory has established that in human mucosal smooth muscle cells (M-SMCs), cellular stress induced by virus or the viral mimic double-stranded RNA (polyinosinic:polycytidylic acid [poly I:C]) increases cell surface hyaluronan (HA) deposition and the formation of long cable-like structures of HA that are important for leukocyte attachment. Since leukocyte accumulation and hyperplasia of the M-SMCs are characteristic pathological changes observed in IBD patients, and phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathways play established roles in cell survival, we investigated whether this pathway is involved in this unique HA-mediated leukocyte attachment. Poly I:C-stimulated M-SMCs bind significantly more monocytic cells than untreated cells and this response was inhibited in a dose-dependent manner by treatment with the PI3K inhibitor, LY294002. Since Akt is a critical downstream regulator of PI3K, we investigated the phosphorylation status of Akt in M-SMCs after treatment with poly I:C for 1 h and found that Akt was phosphorylated, but the phosphorylated Akt band was undetectable in LY294002 plus poly I:C-treated cultures. Confocal microscopy of M-SMCs stained for HA revealed that HA cable formation after poly I:C treatment was abrogated by LY294002. These results demonstrate that poly I:C-stimulated M-SMCs phosphorylate Akt, produce HA cables, and promote HA-mediated leukocyte adhesion through a PI3K/Akt-dependent manner.
authors.affiliation: Department of Pathobiology, Lerner Research Institute , Cleveland Clinic, Cleveland, Ohio 44195, USA. bandyos@ccf.org
authors.forename: Sudip K
authors.initials: SK
authors.lastname: Bandyopadhyay
authors.forename: Carol A
authors.initials: CA
authors.lastname: de la Motte
authors.forename: Alana K
authors.initials: AK
authors.lastname: Majors
authors.forename: Scott A
authors.initials: SA
authors.lastname: Strong
mesh_terms: D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology; D002867:Chromones / Q000494:pharmacology; D006801:Humans; D006820:Hyaluronic Acid / Q000276:immunology / Q000378:metabolism*; D018928:Immunity, Mucosal; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy / Q000276:immunology* / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D009025:Morpholines / Q000494:pharmacology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011070:Poly I-C / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D020298:U937 Cells
chemical_list: D002867:Chromones; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D006820:Hyaluronic Acid; D011070:Poly I-C