title: Bryostatin-1 attenuates TNF-induced epithelial barrier dysfunction: role of novel PKC isozymes.
abstract: Tumor necrosis factor (TNF) increases epithelial permeability in many model systems. Protein kinase C (PKC) isozymes regulate epithelial barrier function and alter ligand-receptor interactions. We sought to define the impact of PKC on TNF-induced barrier dysfunction in T84 intestinal epithelia. TNF induced a dose- and time-dependent fall in transepithelial electrical resistance (TER) and an increase in [(3)H]mannitol flux. The TNF-induced fall in TER was not PKC mediated but was prevented by pretreatment with bryostatin-1, a PKC agonist. As demonstrated by a pattern of sensitivity to pharmacological inhibitors of PKC, this epithelial barrier preservation was mediated by novel PKC isozymes. Bryostatin-1 reduced TNF receptor (TNF-R1) surface availability, as demonstrated by radiolabeled TNF binding and cell surface biotinylation assays, and increased TNF-R1 receptor shedding. The pattern of sensitivity to isozyme-selective PKC inhibitors suggested that these effects were mediated by activation of PKC-epsilon. In addition, after bryostatin-1 treatment, PKC-delta and TNF-R1 became associated, as determined by mutual coimmunoprecipitation assay, which has been shown to lead to receptor desensitization in neutrophils. TNF-induced barrier dysfunction occurs independently of PKC, but selective modulation of novel PKC isozymes may regulate TNF-R1 signaling.
authors.affiliation: Department of Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
authors.forename: James
authors.initials: J
authors.lastname: Yoo
authors.forename: Anthony
authors.initials: A
authors.lastname: Nichols
authors.forename: Jaekyung C
authors.initials: JC
authors.lastname: Song
authors.forename: Joshua
authors.initials: J
authors.lastname: Mammen
authors.forename: Isabel
authors.initials: I
authors.lastname: Calvo
authors.forename: Roger T
authors.initials: RT
authors.lastname: Worrell
authors.forename: John
authors.initials: J
authors.lastname: Cuppoletti
authors.forename: Karl
authors.initials: K
authors.lastname: Matlin
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Matthews
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D054713:Bryostatins; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007783:Lactones / Q000494:pharmacology*; D018942:Macrolides; D008353:Mannitol / Q000493:pharmacokinetics; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014316:Tritium; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D015703:Antigens, CD; D000970:Antineoplastic Agents; D054713:Bryostatins; D007457:Iodine Radioisotopes; D007783:Lactones; D018942:Macrolides; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D014316:Tritium; C046785:bryostatin 1; D008353:Mannitol; C497258:PRKCD protein, human; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D051744:Protein Kinase C-epsilon