Cadmium induces both pyruvate kinase and Na+/H+exchanger activity through protein kinase C mediated signal transduction, in isolated digestive gland cells ofMytilus galloprovincialis(L.)

Abstract

SUMMARYThe present study investigates the transduction pathway mediated by cadmium in isolated digestive gland cells of mussel Mytilus galloprovincialis. The effects of cadmium treatment on a key glycolytic enzyme, pyruvate kinase (PK), and on Na+/H+ exchanger activity were examined. Cadmium (50 μmol l–1) caused a significant elevation of intracellular pH (pHi) and a rise (176%) of Na influx relative to control values. The amiloride analogue, EIPA (20 nmol l–1), a Na+/H+ exchanger blocker,together with cadmium, significantly reduced the effect of treatment by cadmium alone on both Na+ influx and pHi. In addition, PK activity was significantly increased after treatment with cadmium. PK activity was inhibited after treatment of cells with amiloride or EIPA together with cadmium. Moreover, phorbol-ester (PMA), a potent activator of protein kinase C(PKC), caused a significant rise in both pHi and PK activity, while staurosporine or calphostin C reversed both events. Adrenaline, isoprenaline and phenylephrine alone or together with cadmium also significantly increased the pHi and PK activity of isolated digestive gland cells. The latter effectors in combination with cadmium showed a synergistic effect on pHi and PK. These responses seem to be blocked by propranolol, metoprolol and prazosin. Our findings suggest a hormone-like effect of cadmium on digestive gland cells. The signal transduction pathway induced by cadmium involves the stimulation of PK, PKC and Na+/H+ exchanger in isolated digestive gland cells of Mytilus galloprovincialis.

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

“…Previously published studies have shown the activation of NHE by heavy metals in HT 29 cells (Hershfinkel et al, 2001) as well as in haemocytes, digestive gland, gills and mantle/gonad cells of mussels (Dailianis and Kaloyianni, 2004;Kaloyianni et al, 2005;Kaloyianni et al, 2006). In addition, it has been reported that activation of NHE enhances ROS production, after exposure to micromolar concentrations of Cd Koutsogiannaki et al, 2006).…”

“…The Cd concentration used was within the range of Cd levels found in Thermaikos Gulf (HCMR, 1997). Moreover, similar concentrations of Cd have been used in other studies, investigating the effects of the metal on cell signalling and its ability to induce cellular toxic effects (Coogan et al, 1992;Misra et al, 1998;Olabarrieta et al, 2001;Pruski and Dixon, 2002;Dailianis and Kaloyianni, 2004;Dailianis et al, 2005;Dailianis, 2009). Specifically, haemocytes were pre-incubated for 20min with either 0.01mmoll -1 forskolin, an adenylyl cyclase (AC) activator, 2moll…”

“…It is regulated mainly by pH i levels and a wide variety of hormones activating protein kinases, such as protein kinase C (PKC) and cAMP/PKA (Sauvage et al, 2000;Pederson et al, 2002). It has also been reported in a recent study that NHE is stimulated under oxidative stress in digestive gland and gill cells of mussels (Dailianis and Kaloyianni, 2004;Koutsogiannaki et al, 2006).…”

“…Cd has been reported to induce signal transduction cascades, such as protein kinase C (PKC), tyrosine kinase and casein kinase II (Adams et al, 2002), and recent studies in our laboratory have shown the induction of a PKC-mediated signal transduction pathway with a concomitant increase of ROS production and Na + /H + exchanger (NHE) stimulation in Cd-treated cells of mussels (Dailianis and Kaloyianni, 2004 expressed integral membrane protein involved in the coupled exchange of Na + with H + in a variety of eukaryotic cells, is considered of vital importance, since it has been suggested to play important roles in cytoskeletal reorganization, cell migration (Reshkin et al, 2000;McHardy et al, 2004;Paradiso et al, 2004;Konstantinidis et al, 2009), regulation of intracellular pH (pH i ) (Moolenaar et al, 1983;Bianchini and Pouyssegur, 1994), cell volume control (Cala, 1983a;Cala, 1983b) and other cell activities such as cell adhesion, proliferation and apoptosis (Tominaga and Barber, 1998;Khaled et al, 2001;Moor et al, 2001;Avkiran and Haworth, 2003;Orlowski and Grinstein, 2004;Koliakos et al, 2008). It is regulated mainly by pH i levels and a wide variety of hormones activating protein kinases, such as protein kinase C (PKC) and cAMP/PKA (Sauvage et al, 2000;Pederson et al, 2002).…”

Tolerancia a la anoxia y defensas antioxidantes en el mejillon verde Perna viridis (Linneus, 1758) bajo exposicion aguda al cadmio

“…Tales niveles de Cd presentes en mejillones y en su entorno crean expectativas sobre las estrategias bioquímicas de defensa en organismos contaminados, en especial en su adaptación a sobrevivir a la anoxia. Distintos estudios han considerado que el Cd puede provocar daños a nivel molecular en los organismos marinos en bajas concentraciones, conllevando a alteraciones en el trasporte a través de las membranas biológicas (Dailianis & Kaloyianni, 2004), actividad enzimática (Canesi et al, 1998;Nusetti et al, 2010), producción energética (Sokolova, 2004) y daños oxidativos (Prakash & Jagannatha-Roa, 1995;Rajkumar & Milton, 2011).…”