Acrylamide-Responsive Genes in the Nematode Caenorhabditis elegans

Abstract

As acrylamide is a known neurotoxin for many animals and potential carcinogen for humans, it came as a surprise when the Swedish National Food Agency and Stockholm University reported in 2002 that it is formed during the frying or baking of foods. We report here genomic and proteomic analyses on genes and proteins of Caenorhabditis elegans exposed to 500 mg/l acrylamide. Of the 21,120 genes profiled, 409 genes were more than twofold upregulated and 111 genes were downregulated. Upregulated genes included many that encode detoxification enzymes such as glutathione S-transferases (GSTs), uridine diphosphate-glucuronosyl/glucosyl transferases, and short-chain type dehydrogenases but only one cytochrome P450. Subsequent proteomic analysis confirmed the heavy involvement of GSTs. Because of their high expression levels and central roles in acrylamide metabolism, we analyzed the in vivo expression patterns of eight gst genes. Although all encoded GST and were more than twofold upregulated by acrylamide treatment, their expression patterns were varied, and their regulation involved the transcription factor SKN-1 (a C. elegans homolog of Nuclear factor E2-related factors 1 and 2). We then selected the gst-4::gfp-transformed C. elegans to study the detoxification rate of acrylamide and its metabolite glycidimide in living animals. This animal detects acrylamide as a green fluorescence protein (GFP) expression signal in a dose- and time-dependent manner and may prove to be a useful tool not only for rapidly and inexpensively detecting acrylamide, a harmful substance in food, but also for analyzing mechanisms of GST induction by acrylamide and other inducers like oxidative stresses.

In vivo Role of Cytochrome P450 2E1 and Glutathione-S-Transferase Activity for Acrylamide Toxicokinetics in Humans

“…Accordingly, an in vitro study showed no influence of GSTM1 or GSTT1 on hemoglobin adduct formation after exposure of human blood samples to acrylamide and glycidamide (75). However, recently the up-regulation of genes encoding GSTs was shown by exposure of Caenorhabditis elegans to 500 mg/L acrylamide, and proteomic analysis confirmed some involvement of GSTs (26). Negative results from our study on the influence of GSTs on acrylamide metabolism support the hypothesis of a primarily nonenzymatic conjugation of acrylamide and glycidamide with glutathione (75).…”

“…Of these, AAMA, its sulfoxide, and GAMA have been unequivocally confirmed in humans (9)(10)(11). Whereas there are many glutathione-S-transferases (GST) in humans and rodents, which may be involved in these metabolic steps, nonenzymatic formation of glutathione conjugates is also possible and has been reported for acrylamide (25,26). The role of GSTs in acrylamide metabolism in humans remains to be assessed.…”

Inhibition of the oxidative stress response by heat stress inCaenorhabditis elegans

“…Paraquat is a synthetic, contact herbicide used throughout the world in agricultural applications (Powles and Yu, 2010). Acrylamide is not likely to affect C. elegans in nature, but it is a strong inducer of SKN-1 transcriptional activity (Hasegawa et al, 2008) and produces oxidative stress in other organisms (Prasad and Muralidhara, 2012).…”

Pollution by metals and toxicity assessment using Caenorhabditis elegans in sediments from the Magdalena River, Colombia

“…The wet sediment was then divided among four 20 mL syringe cylinders plugged with a stainless steel mesh disc and glass wool (Hasegawa et al, 2008). The cylinders were placed in 50 mL plastic tubes and centrifuged at 4,500 g for ten min.…”

“…GSTs consists of ubiquitous, dimeric proteins involved in the detoxification of endogenous and xenobiotic compounds by glutathione conjugation, peroxidase activity or passive binding, supporting the conversion of GSH to electrophilic GS À , which binds to toxic compounds and leads their excretion (Campbell et al, 2001). Among them, gst-1 and gst-4 are strongly inducible by organic compounds (Hasegawa et al, 2008).…”