The role of signalling molecules on actin glutathionylation and protein carbonylation induced by cadmium in haemocytes of mussel<i>Mytilus galloprovincialis</i>(Lmk)

Abstract

This study investigated the role of Na(+)/H(+) exchanger (NHE) and signalling molecules, such as cAMP, PKC, PI 3-kinase, and immune defence enzymes, NADPH oxidase and nitric oxide synthase, in the induction of protein glutathionylation and carbonylation in cadmium-treated haemocytes of mussel Mytilus galloprovincialis. Glutathionylation was detected by western blot analysis and showed actin as its main target. A significant increase of both actin glutathionylation and protein carbonylation, were observed in haemocytes exposed to micromolar concentration of cadmium chloride (5 micromol l(-1)). Cadmium seems to cause actin polymerization that may lead to its increased glutathionylation, probably to protect it from cadmium-induced oxidative stress. It is therefore possible that polymerization of actin plays a signalling role in the induction of both glutathionylation and carbonylation processes. NHE seems to play a regulatory role in the induction of oxidative damage and actin glutathionylation, since its inhibition by 2 micromol l(-1) cariporide, significantly diminished cadmium effects in each case. Similarly, attenuation of cadmium effects were observed in cells pre-treated with either 11 micromol l(-1) GF-109203X, a potent inhibitor of PKC, 50 nmol l(-1) wortmannin, an inhibitor of PI 3-kinase, 0.01 mmol l(-1) forskolin, an adenylyl cyclase activator, 10 micromol l(-1) DPI, a NADPH oxidase inhibitor, or 10 micromol l(-1) L-NAME, a nitric oxide synthase inhibitor, suggesting a possible role of PKC, PI 3-kinase and cAMP, as well as NADPH oxidase and nitric oxide synthase in the enhancement of cadmium effects on both actin glutathionylation and protein carbonylation.