title: Beta-1, 3-glucan modulates PKC signalling in Lymnaea stagnalis defence cells: a role for PKC in H2O2 production and downstream ERK activation.
abstract: Haemocytes from the gastropod snail Lymnaea stagnalis (Linnaeus) were used as a model to characterize protein kinase C (PKC) signalling events in molluscan defence cells. Challenge of freshly collected haemocytes with the beta-1, 3-glucan laminarin resulted in a transient increase in the phosphorylation of haemocyte PKC, with maximal phosphorylation (represented by a 3.5-fold increase) occurring at 10 min; this effect was blocked by the PKC inhibitor, GF109203X. Moreover, extracellular signal-regulated kinase (ERK) was found to be a downstream target of molluscan PKC, operating via a MAPK/ERK kinase (MEK)-dependent mechanism. Pharmacological inhibition of PKC phosphorylation by U-73122 and ET-18-OCH(3) suggested that laminarin-dependent PKC signalling was modulated via phospholipase C (PLC); however, a role for phosphatidylinositol-3-kinase (PI-3-K) is unlikely since the PI-3-K inhibitor LY294002 was without effect. Generation of H(2)O(2) by haemocytes in response to laminarin was also investigated. H(2)O(2) output increased in a dose- and time-dependent manner, with 10 mg ml(-1) laminarin eliciting a 9.5-fold increase in H(2)O(2) production after 30 min. H(2)O(2) production was significantly attenuated by the PKC inhibitors, GF109203X and Gö 6976, and by the NADPH-oxidase inhibitor, apocynin. In conclusion, these data further our understanding of PKC signalling events in molluscan haemocytes and for the first time define a role for PKC in H(2)O(2) production by these defence cells. Given that H(2)O(2) is an important anti-pathogen molecule, and that haemocytes play a crucial role in the elimination of invading organisms, PKC signalling in these cells is likely to be crucial to the molluscan innate defence response.
authors.affiliation: School of Life Sciences, Kingston University, Penrhyn Road, Kingston upon Thames, Surrey, KT1 2EE, UK.
authors.forename: Audrey H
authors.initials: AH
authors.lastname: Lacchini
authors.forename: Angela J
authors.initials: AJ
authors.lastname: Davies
authors.forename: David
authors.initials: D
authors.lastname: Mackintosh
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Walker
mesh_terms: D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005936:Glucans; D006434:Hemocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D008195:Lymnaea / Q000166:cytology / Q000201:enzymology*; D008301:Maleimides / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010742:Phospholipid Ethers / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011134:Polysaccharides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D047071:beta-Glucans / Q000494:pharmacology*
chemical_list: D002227:Carbazoles; D004963:Estrenes; D005936:Glucans; D007211:Indoles; D008301:Maleimides; D010742:Phospholipid Ethers; D011134:Polysaccharides; D047428:Protein Kinase Inhibitors; D011760:Pyrrolidinones; D017382:Reactive Oxygen Species; D047071:beta-Glucans; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C081021:Go 6976; C026659:edelfosine; C008247:laminaran; C033363:beta-1,3-glucan; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; C070515:bisindolylmaleimide I