Genetic analysis of oxidative and endoplasmic reticulum stress responses induced by cobalt toxicity in budding yeast

• Published in: Biochimica et biophysica acta. General subjects 2020-03, Vol.1864 (3), p.129516, Article 129516
• Main Authors: Zhao, Yun-ying, Cao, Chun-lei, Liu, Ying-li, Wang, Jing, Li, Shi-yun, Li, Jie, Deng, Yu
• Format: Article
• Language: English
• Subjects: Cobalt; Endoplasmic reticulum stress; Reactive oxygen species (ROS); Yeast
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2020.129516

Cobalt is an important metal cofactor of many living cells. However, excessive cobalt is toxic and can cause cell death and even several diseases in humans. Saccharomyces cerevisiae is a useful tool for studying metal homeostasis and many of the genes and pathways are highly conserved in higher eukaryotes including humans. The intracellular cobalt and reactive oxygen species (ROS) levels were measured by an atomic absorption spectrometer and DHE staining method, respectively. The expression of genes involved in scavenging oxidative stress was tested by qPCR method, while the expression of UPRE-lacZ report gene was analyzed via β-galactosidase activity assay. Using a genome-scale genetic screen, 153 cobalt-sensitive and 37 cobalt-tolerant gene deletion mutants were identified from Saccharomyces cerevisiae. We showed that 101 of the cobalt-sensitive mutants accumulated higher intracellular cobalt compared to wild-type. The intracellular ROS levels in 112 of the mutants were induced by cobalt, which might be caused by the decreased expression of genes involved in scavenging oxidative stress in response to cobalt. Moreover, more than one-third of the cobalt-sensitive mutants were also sensitive to tunicamycin, and cobalt stress might induce the unfolded protein response (UPR) through serine/threonine kinase and endoribonuclease Ire1. This study reinforced the fact that cobalt toxicity might be due to the high intracellular cobalt and ROS levels, and the endoplasmic reticulum stress responses induced by cobalt. Elucidating the toxicity mechanisms of cobalt stress response will help reveal new routes for the treatment of the diseases induced by cobalt. Suggested model for the toxicity mechanisms of cobalt stress. Cells uptake the extracellular cobalt via the plasma membrane transporters Smf2, Fet4 and Pho84. Once inside the cell, cobalt generates ROS, causing DNA damage and lipid/protein oxidation, thus inducing the ER stress. The oxidative damage caused by cobalt can be alleviated by inducing the genes involved in oxidative stress scavenging. [Display omitted] •Cobalt-sensitive and -tolerant mutants were both identified•Cobalt generates ROS by inducing genes involved in scavenging oxidative stress•Cobalt induces UPR through Ire1•Cobalt toxicity was caused by High intracellular cobalt and ROS levels, ER stress