Phagocytosis by Lymnaea stagnalis haemocytes: A potential role for phosphatidylinositol 3-kinase but not protein kinase A

Plows, Louise D.; Cook, Richard T.; Davies, Angela J.; Walker, Anthony J.

doi:10.1016/j.jip.2005.10.011

Cited by 35 publications

(14 citation statements)

References 24 publications

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“…Our present findings also corroborate previous work in which we showed that ERK activation in L. stagnalis haemocytes was unaffected by LY294002 (Plows et al, 2004), implying that the regulation of PKC/MEK/ERK phosphorylation in these cells is PI-3-K independent. It can therefore also be concluded that the recently reported inhibitory effect of LY294002 on phagocytosis by L. stagnalis haemocytes (Plows et al, 2006), is likely mediated by PKC-and ERK-independent mechanisms.…”

Section: Production Of H 2 O 2 By Laminarin-stimulated Haemocytes Ismentioning

confidence: 77%

“…A second phospholipase C inhibitor, ET-18-OCH 3 , used at the same range of concentrations (0.001-10·mol·l -1 ) also inhibited PKC phosphorylation (Fig.·5B) with 10·mol·l -1 ET-18-OCH 3 reducing PKC phosphorylation by 73% (data not shown). In order to evaluate whether PI-3-K acts upstream of PKC in laminarin-challenged haemocytes, monolayers were treated with various doses of the PI-3-K inhibitor, LY294002 (0.001-10·mol·l -1 ), prior to challenge; we have recently shown that this inhibitor attenuates the phagocytic activity of L. stagnalis haemocytes by 62% (Plows et al, 2006). Western blotting revealed that LY294002 did not reduce levels of phosphorylated PKC at any dose tested (Fig.·5C), indicating that haemocyte PKC activity is not under the control of PI-3-K in laminarin-challenged haemocytes.…”

Section: Pkc Phosphorylation (Activation) Is Controlled By the Upstrementioning

confidence: 99%

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β-1, 3-glucan modulates PKC signalling inLymnaea stagnalisdefence cells: a role for PKC in H2O2 production and downstream ERK activation

Lacchini

Davies

Mackintosh

et al. 2006

Journal of Experimental Biology

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SUMMARY 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 theβ-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-OCH3 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 H2O2 by haemocytes in response to laminarin was also investigated. H2O2 output increased in a dose- and time-dependent manner, with 10 mg ml-1 laminarin eliciting a 9.5-fold increase in H2O2 production after 30 min. H2O2 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 H2O2 production by these defence cells. Given that H2O2 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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Section: Production Of H 2 O 2 By Laminarin-stimulated Haemocytes Ismentioning

confidence: 77%

Section: Pkc Phosphorylation (Activation) Is Controlled By the Upstrementioning

confidence: 99%

β-1, 3-glucan modulates PKC signalling inLymnaea stagnalisdefence cells: a role for PKC in H2O2 production and downstream ERK activation

Lacchini

Davies

Mackintosh

et al. 2006

Journal of Experimental Biology

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“…In snails such as Lymnaea stagnalis, circulating phagocytes called haemocytes are the sentinels and effectors of the internal defence system. These cells recognize 'non-self' and respond by phagocytosing or encapsulating intruding organisms (Plows et al 2006a), and by producing cytotoxic metabolites, such as reactive oxygen and nitrogen intermediates, to kill the intruder Wright et al 2006). Encapsulation, occurring when intruding organisms (e.g., non-compatible parasites) are too large to be phagocytosed, requires coordinated interactions between haemocytes which adhere to and spread on the invading organism and adjacent cells, thus isolating the intruder within a 'capsule'; the intruder is then killed by cytotoxic mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Spreading by snail (Lymnaea stagnalis) defence cells is regulated through integrated PKC, FAK and Src signalling

et al. 2010

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Cell adhesion and spreading are vital to immune function. In molluscs, haemocytes (circulating phagocytes) are sentinels and effectors of the internal defence system; however, molecular mechanisms that regulate integrin-mediated spreading by haemocytes have not been characterised in detail. Visualisation of Lymnaea stagnalis haemocytes by scanning electron microscopy revealed membrane ruffling, formation of lamellipodia and extensive filopodia during early stages of cell adhesion and spreading. These events correlated with increased phosphorylation (activation) of protein kinase C (PKC) and focal adhesion kinase (FAK), sustained for 60 min. Treatment of haemocytes with the PKC inhibitors GF109203X or Gö 6976, or the Src/tyrosine kinase inhibitors SrcI or herbimycin A, attenuated haemocyte spread by 64, 46, 32 and 35%, respectively (P

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“…Phagocytosis has been studied in many invertebrates, including molluscs like the snail, Lymnaea stagnalis, and the clam, Mya arenaria [5,6]. Circulating haemocytes are the key phagocytes of molluscs.…”

Section: Introductionmentioning

confidence: 99%

Induction of phenoloxidase and other immunological activities in Sydney rock oysters challenged with microbial pathogen-associate molecular patterns

Aladaileh

Nair

Raftos

2007

Fish & Shellfish Immunology

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Phagocytosis by Lymnaea stagnalis haemocytes: A potential role for phosphatidylinositol 3-kinase but not protein kinase A

Cited by 35 publications

References 24 publications

β-1, 3-glucan modulates PKC signalling inLymnaea stagnalisdefence cells: a role for PKC in H2O2 production and downstream ERK activation

β-1, 3-glucan modulates PKC signalling inLymnaea stagnalisdefence cells: a role for PKC in H2O2 production and downstream ERK activation

Spreading by snail (Lymnaea stagnalis) defence cells is regulated through integrated PKC, FAK and Src signalling

Induction of phenoloxidase and other immunological activities in Sydney rock oysters challenged with microbial pathogen-associate molecular patterns

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