Investigation of artemisininresistance in yeast lacking P-type atpase, PMR1Kanate Thitiananpakorn
( M.Sc. )
Amornrat Naranuntarat Jensen
Artemisinin and its derivatives are widely used as a medicine for malarial treatment dueto their high efficacy and minimal side effects. In addition, artemisinin is also active against parasites that are already resistant to other types of antimalarial drugs. The mechanisms of action of artemisinin have been proposed to occur through a generation of reactive oxygen species as well as through an inhibition of PfATP6, the calcium transporter on the endoplasmic reticulum membrane (SERCA). In this study, we utilized the yeast Saccharomyces cerevisiae as a model organism to investigate the mechanism of artemisinin toxicity. We found that cells lacking a yeast SERCA orthologue P-typr ATPase, Pmr 1 p, is resistant to artemisinin. However, loss of repiratory activity and hyperaccumulation of intracellular Ca2+ and Mn2+ in pmr 1 D are not the causes of artemisinin resistance. Moreover, artemisinin toxicity via Pmr 1 p inhibition does not appear to result from an induction of unfolded protein response, a signaling cascade in response to a perturbation of calcium homeostasis that leads to ER stress or reduced levels of protein glycosylation, a calcium-dependent protein maturation process. A plasma membrane expression of Pdr5p. a drug efflux transporter, is also not altered in pmr 1 D. We demonstrated herein that intracellular ROS accumulation under artemisinin exposure is significantly reduced in cells lacking Pmr 1 p. Overall, our studies have revealed that artemisinin toxicology requires Pmr 1 p to promote ROS generation and thus cell death.
Artemisinin / Pmr 1 p / ROS / malaria / calcium and manganese metabolism