| 17142672 |
Lacchini AH, Davies AJ, Mackintosh D, Walker AJ: Beta-1, 3-glucan modulates PKC signalling in Lymnaea stagnalis defence cells: a role for PKC in H2O2 production and downstream ERK activation. J Exp Biol. 2006 Dec;209(Pt 24):4829-40.
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 Go 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. |
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