Heavy Metals and Metalloids as Autophagy Inducing Agents: Focus on Cadmium and Arsenic

Abstract: In recent years, research on the autophagic process has greatly increased,invading the fields of biology and medicine. Several markers of the autophagic processhave been discovered and various strategies have been reported studying this molecularprocess in different biological systems in both physiological and stress conditions.Furthermore, mechanisms of metalloid- or heavy metal-induced toxicity continue to beof interest given the ubiquitous nature and distribution of these contaminants in theenvironment where they often play the role of pollutants of numerous organisms. The aimof this review is a critical analysis and correlation of knowledge of autophagic mechanismsstudied under stress for the most common arsenic (As) and cadmium (Cd) compounds. Inthis review we report data obtained in different experimental models for each compound,highlighting similarities and/or differences in the activation of autophagic processes.A more detailed discussion will concern the activation of autophagy in Cd-exposed seaurchin embryo since it is a suitable model system that is very sensitive to environmentalstress, and Cd is one of the most studied heavy metal inductors of stress and modulator ofdifferent factors such as: protein kinase and phosphatase, caspases, mitochondria, heatshock proteins, metallothioneins, transcription factors, reactive oxygen species, apoptosisand autophagy.