The role of signalling molecules on actin glutathionylation and protein carbonylation induced by cadmium in haemocytes of musselMytilus galloprovincialis(Lmk)

Abstract

SUMMARYThis 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mol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moll -1 cariporide, significantly diminished cadmium effects in each case. Similarly, attenuation of cadmium effects were observed in cells pre-treated with either 11mol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moll -1 DPI, a NADPH oxidase inhibitor, or 10mol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.

Effect of 17β-estradiol on adhesion of Mytilus galloprovincialis hemocytes to selected substrates. Role of alpha2 integrin subunit

“…Our results also indicate that the mechanism of 17b-estradiol-induced adhesion to laminin-1, collagen IV and oxidized collagen IV involves a large number of intracellular components, one of which is NHE. It is well known that NHE is commonly linked to cytoskeleton, thus participating in signal transduction pathways [37,54,55]. Our results showed that inhibition of NHE caused a significant attenuation of 17b-estradiol ability to enhance hemocyte adhesion to ECM proteins, a fact that could lead to the suggestion that NHE could be an important regulator of cell adhesion.…”

“…Previous studies from our laboratory have shown that cAMP is involved in signaling pathways mediating oxidative responses induced by heavy metals in M. galloprovincialis hemocytes [55]. In addition, other studies suggest that low cytosolic cAMP inhibits phagocytosis in the bivalves Biomphalaria glabarata [86], Crassostrea gigas [87] as well as substratum adhesion of Mytilus californianus hemocytes [88].…”

Cerebral Myogenic Reactivity and Blood Flow in Type 2 Diabetic Rats: Role of Peroxynitrite in Hypoxia-Mediated Loss of Myogenic Tone

“…Second, based on previous studies, we postulated that the effects observed in OGD would be mediated by ONOO Ϫ ; however, we cannot discount the contribution of other sources of oxidative and nitrosative stress on vascular reactivity, tone, and structure. Also, it is possible that the irreversible reduction in actin cytoskeleton polymerization observed in OGD-treated vessels results in oxidative stress-mediated glutathionylation of actin cysteinyl residues or protein aggregation due to carbonylation and may not be the result of protein nitration, as previous hypothesized (Johansson and Lundberg, 2007;Dailianis et al, 2009). Finally, the results obtained in vessels from diabetic animals cannot be explained solely by the effects of oxidative stress generated during hypoxic conditions.…”

Total thiol redox status as a potent biomarker of PAH-mediated effects on mussels

“…In fact, in the strongly reducing intracellular environment, protein cysteines, mainly in reduced state, are susceptible to oxidation and the concomitant transient formation of intramolecular or intermolecular disulfides with GSH (Ghezzi, 2005;McDonagh and Sheehan, 2007). Similarly, Dailianis et al (2009) reported the formation of reversible mixed disulfides between GSH and cysteine in haemocytes of mussels faced with pro-oxidants after 6 days of exposure, possibly to mask sulfhydryl groups until oxidative stress is overcome. According to the latter, the significant depletion of both PSH and GSH in gills of PAHexposed mussels, as well as the significant correlation obtained among the aforementioned parameters, reveals that thiol modifications due to protein misfolding and disulfide bond formation could be associated with PAH-mediated oxidative stress, thus providing a valuable tool in understanding the cellular redox status.…”