Zinc- and oxidative property-dependent degradation of pro-caspase-1 and NLRP3 by ziram in mouse macrophages.
The NLRP3 inflammasome, composed of caspase-1, NLRP3 and ASC, plays a critical role in the clearance of microbial pathogens. Here, we found that the treatment of mouse macrophages with the zinc-containing dithiocarbamate ziram, a widely used fungicide in agriculture, caused a decrease in pro-caspase-1 and NLRP3 levels while not affecting ASC level. Ziram did not affect levels of pro-caspase-1 and NLRP3 mRNA, and no cleavage products of pro-caspase-1 including p10 subunit, which is an autocleavage product of pro-caspase-1, were detected, indicating that the decrease was associated with degradation of these proteins. The decrease was inhibited by SH-type antioxidants, N-acetyl cysteine, dithiothreitol and 2-mercaptoethanol, or a metal chelator EDTA but not by inhibitors of proteasome, lysosomes, autophagy and matrix metalloproteases. Thiram, a comparator for ziram that does not contain zinc, showed a weaker decrease in protein levels. Furthermore, the zinc-containing dithiocarbamate, zinc diethyldithiocarbamate, efficiently decreased the levels of pro-caspase-1 and NLRP3, whereas dithiocarbamates, dimethyldithiocarbamate and diethyldithiocarbamate without zinc, were less active. The organic zinc compound [3,4-toluenedithiolato(2-)]zinc hydrate did not induce a decrease in protein levels. Ziram also inhibited IL-1β production by macrophages in response to lipopolysaccharide and bacterial clearance during Salmonella infection of macrophage cells. These results indicate that ziram causes degradation of pro-caspase-1 and NLRP3 in a zinc- and oxidative property-dependent manner and suggest that exposure to ziram may compromise the clearance of microbial pathogens.
Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585, Japan. Electronic address: mamuro@musashino-u.ac.jp.
Masashi
M
Muroi
Research Institute of Pharmaceutical Sciences, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585, Japan.
Ken-ichi
K
Tanamoto
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D020170:Caspase 1 / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D005659:Fungicides, Industrial / Q000633:toxicity*; D005786:Gene Expression Regulation / Q000187:drug effects; D020382:Interleukin-18 / Q000235:genetics / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D010084:Oxidation-Reduction; D015032:Zinc / Q000494:pharmacology*; D015039:Ziram / Q000633:toxicity*
D002352:Carrier Proteins; D005659:Fungicides, Industrial; D020382:Interleukin-18; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; D015039:Ziram; D020170:Caspase 1; D015032:Zinc
Caspase; Inflammation; NLRP3 inflammasome; Oxidative stress; Ziram