title: Differential activation of signal transduction pathways mediating phagocytosis, oxidative burst, and degranulation by chicken heterophils in response to stimulation with opsonized Salmonella enteritidis.
abstract: The activation of signal transduction pathways is required for the expression of functional enhancement of cellular activities. In the present studies, initial attempts were made to identify the signal transduction factors involved in activating phagocytosis, generation of an oxidative burst, and degranulation by heterophils isolated from neonatal chickens in response to opsonized Salmonella enteritidis (opsonized SE). Peripheral blood heterophils were isolated and exposed to known inhibitors of signal transduction pathways for either 20 min (staurosporin, genistein, or verapamil) or 120 min (pertussis toxin) at 39 degrees C. The cells were then stimulated for 30 min at 39 degrees C with opsonized SE. Phagocytosis, luminol-dependent chemoluminescence (LDCL), and beta-D glucuronidase release were then evaluated in vitro. The G-protein inhibitor pertussin toxin markedly inhibited (>80%) phagocytosis of opsonized SE. Both the protein kinase inhibitor (staurosporin) and calcium channel inhibitor (verapamil) reduced phagocytosis in a dose response manner. Genistein, a tyrosine kinase inhibitor, had no effect on phagocytosis. Staurosporin had a marked inhibitory effect on LDCL (>90%) while genistein had a dose responsive inhibition on LDCL. Both verapamil (40-45%) and pertussin toxin (50-55%) had a statistically significant, but less biologically significant effect on LDCL. Genistein significantly reduced the degranulation (78-81%) of heterophils by opsonized SE. Staurosporin also reduced degranulation by 43-50%, but neither verapamil nor pertussis toxin had a significant effect on degranulation. These findings demonstrate that distinct signal transduction pathways differentially regulate the stimulation of the functional activities of avian heterophils. Pertussin toxin-sensitive, Ca++-dependent G-proteins appear to regulate phagocytosis of opsonized SE, protein kinase C-dependent, tyrosine kinase-dependent protein phosphorylation plays a major role in LDCL, and tyrosine kinase(s)-dependent phosphorylation regulates primary granule release.
authors: USDA-Agricultural Research Service, Southern Plains Agricultural Research Center, College Station, Texas 77845, USA.
authors: M H
authors: MH
authors: Kogut
authors: K J
authors: KJ
authors: Genovese
authors: V K
authors: VK
authors: Lowry
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D002645:Chickens / Q000276:immunology*; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors; D019833:Genistein / Q000494:pharmacology; D005966:Glucuronidase / Q000378:metabolism; D008163:Luminescent Measurements; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D009895:Opsonin Proteins / Q000276:immunology; D037342:Pertussis Toxin; D010587:Phagocytosis / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011201:Poultry Diseases / Q000276:immunology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D016897:Respiratory Burst / Q000187:drug effects; D012481:Salmonella Infections, Animal / Q000276:immunology; D012477:Salmonella enteritidis / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects; D019311:Staurosporine / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D009895:Opsonin Proteins; D010566:Virulence Factors, Bordetella; D014700:Verapamil; D019833:Genistein; D037342:Pertussis Toxin; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D005966:Glucuronidase; D019204:GTP-Binding Proteins; D019311:Staurosporine