Identification of Dynamic Changes in Proteins Associated with the Cellular Cytoskeleton after Exposure to Okadaic Acid

Abstract

Exposure of cells to the diarrhetic shellfish poison, okadaic acid, leads to a dramatic reorganization of cytoskeletal architecture and loss of cell-cell contact. When cells are exposed to high concentrations of okadaic acid (100–500 nM), the morphological rearrangement is followed by apoptotic cell death. Okadaic acid inhibits the broad acting Ser/Thr protein phosphatases 1 and 2A, which results in hyperphosphorylation of a large number of proteins. Some of these hyperphosphorylated proteins are most likely key players in the reorganization of the cell morphology induced by okadaic acid. We wanted to identify these phosphoproteins and searched for them in the cellular lipid rafts, which have been found to contain proteins that regulate cytoskeletal dynamics and cell adhesion. By using stable isotope labeling by amino acids in cell culture cells treated with okadaic acid (400 nM) could be combined with control cells before the isolation of lipid rafts. Protein phosphorylation events and translocations induced by okadaic acid were identified by mass spectrometry. Okadaic acid was shown to regulate the phosphorylation status and location of proteins associated with the actin cytoskeleton, microtubules and cell adhesion structures. A large number of these okadaic acid-regulated proteins have previously also been shown to be similarly regulated prior to cell proliferation and migration. Our results suggest that okadaic acid activates general cell signaling pathways that induce breakdown of the cortical actin cytoskeleton and cell detachment.

Proteomic profile in Perna viridis after exposed to Prorocentrum lima, a dinoflagellate producing DSP toxins

“…Combined with down-regulation of annexins and actin-related protein 2, 3, we speculated that P. lima and associated DSP toxins might induce cytoskeletonal disorganization of mussel gills. Actually, OA-induced changes in cytoskeletal architecture and cellecell contact have been extensively reported (Leira et al, 2001;Espiña and Rubiolo, 2008;Vale and Botana, 2008;Vilariño et al, 2008;Espiña et al, 2010;Wang et al, 2011;Hanana et al, 2012;Huang et al, 2013;Opsahl et al, 2013). Using a mussel cDNA microarray, Manfrin et al (2010) found that 9% of up-regulated transcripts in mussel induced by OA exposure were potentially involved in cytoskeleton organization.…”

Toxins of Okadaic Acid-Group Increase Malignant Properties in Cells of Colon Cancer

“…It has been described that this group of toxins can behave as both cell death inducers and tumor promoters [20]. Del Campo et al [2] stated that this dual effect of OA depends on the administered dose and applied exposure time, since in gastric epithelium (AGS and MKN45) and colon epithelium (Caco 2) models, sublethal doses of OA promote cell proliferation and activate oncogenic pathways [2]; however, only the effects on tumoral cells were studied herein, and nontumoral cells were excluded from it.…”

Regulatory volume decrease in isolated nematocytes is affected by crude venom from the jellyfish Pelagia noctiluca

“…In this regard, other investigations have been attempted to link changes in cytoskeleton components with volume changes, and, more interestingly, to verify if drug-induced alterations of cytoskeleton affect cell volume regulation processes. 30 In addition, non-lytic doses of crude venom from Pelagia noctiluca directly induce mitochondrial trans-membrane potential collapse and generation of reactive oxygen species (ROS) in neuronal-like (SH-SY5Y) cells. 15 Mitochondrial membrane alterations are possibly due to Article Figure 4.…”