Abstract
We recently established the MerB, bacterial organomercurial lyase, expressing HEK293 cells (MerB-cells) and showed that MerB could demethylate MeHg and convert inorganic mercury in mammalian cells and MerB-cells were significantly more sensitive to MeHg exposure compared to the parental cells1). However, the cellular response to inorganic mercury derived from MeHg has yet fully to be elucidated. The objective of this study is to assess the autophagic response in MerB-expressing HEK293 (MerB-cells) exposed to MeHg. The level of membrane-bound LC3-II in MerB-cells exposed with MeHg was increased in a dose-dependent manner and enhanced compared to the parental cells. Next, to investigate whether LC3-II accumulation is ascribable to induction of autophagy or blockade of autophagic degradation steps, we performed an autophagy flux assay using chloroquine (CQ), which prevents fusion between autophagosomes and lysosomes. Compared with CQ treatment alone, cotreatment with MeHg increased the LC3-II levels. Our data suggest that Hg2+ activates autophagy and exhibits a stronger autophagic response than that MeHg.
1) Intracellular demethylation of methylmercury to inorganic mercury by organomercurial lyase (MerB) strengthens cytotoxicity. 2019, Toxicol. Sci.
