Algal Toxin Azaspiracid-1 Induces Early Neuronal Differentiation and Alters Peripherin Isoform Stoichiometry.

Azaspiracid-1 is an algal toxin that accumulates in edible mussels, and ingestion may result in human illness as manifested by vomiting and diarrhoea. When injected into mice, it causes neurotoxicological symptoms and death. Although it is well known that azaspiracid-1 is toxic to most cells and cell lines, little is known about its biological target(s). A rat PC12 cell line, commonly used as a model for the peripheral nervous system, was used to study the neurotoxicological effects of azaspiracid-1. Azaspiracid-1 induced differentiation-related morphological changes followed by a latter cell death. The differentiated phenotype showed peripherin-labelled neurite-like processes simultaneously as a specific isoform of peripherin was down-regulated. The precise mechanism behind this down-regulation remains uncertain. However, this study provides new insights into the neurological effects of azaspiracid-1 and into the biological significance of specific isoforms of peripherin.

Proteomic response of human neuroblastoma cells to azaspiracid-1.

Azaspiracid-1 is a novel algal toxin, which causes an instantaneous rise of intracellular messengers, and an irreversible disarrangement of the actin cytoskeleton. Little is known regarding the molecular mechanisms that are involved in azaspiracid-1 toxicity. This study investigated global changes in protein expression by stable-isotope labelling with amino acids in culture and mass spectrometry, following exposure of human neuroblastoma cells to azaspiracid-1. The most highly upregulated proteins were involved in cellular energy metabolism, followed by cytoskeleton regulating proteins. The majority of downregulated proteins were involved in transcription, translation and protein modification. In addition, two proteins, component of oligomeric Golgi complex 5 and ras-related protein RAB1, which are involved in the maintenance of the Golgi complex and vesicle transport, respectively, were downregulated. Electron microscopy revealed a disruption of the Golgi complex by azaspiracid-1, and an accumulation of vesicles. In this study, the differential protein expression was examined prior to changes of the cytoskeleton structure in order to capture the primary effects of azaspiracid-1, however the observed changes were of unexpected complexity. Azaspiracid-1 caused a pronounced, but temporary depletion of ATP, which may be the reason for the observed complexity of cellular changes.