Characterization of DJ-1 and Glyoxalase 1 knockout mice

Abstract

Methylglyoxal and glyoxal are highly reactive $\alpha$-oxoaldehyde, which are physiologically generated from various metabolic pathways. They reacts with arginine, lysine and cysteine residues of proteins and guanine nucleotides of DNA or RNA, leading to protein malfunction and mutation on genetic material, causing various disease such as diabetes complication and neurodegenerative disease. Several detoxification mechanisms exist to control these reactive aldehydes, including glyoxalase system, AKR, and DJ-1 glyoxalase. The glyoxalase system, which consists of two enzymes, glyoxalase 1 (Glo1) and glyoxalase 2 (Glo2), is considered to be the main detoxification pathway of methylglyoxal. Here, we generated Glo1 knockout mice from the ES cell carrying $Glo1^{tm1a(KOMP)Mbp}$ allele, which purchased from KOMP. This is the first reported Glo1 knockout mice. Glo1 knockout mice were non-lethal, exhibit normal gross phenotype, normal reproductive functions, and survived more than 2 years. Generated knockout mice were confirmed by PCR, western blot, and enzyme activity analysis. Accumulation of MG-H1 in Glo1 knockout mice liver was detected by western blot, whereas brain did not. No significant difference detected in total GSH level between wild-type and knockout mice. DJ-1, autosomal recessive early onset familial Parkinson’s disease associated protein, revealed as a novel glyoxalase, which catalyze glyoxal / methylglyoxal into glycolate / L-lactate without any cofactor. Unlike glyoxalase system and AKR, which have a higher activity with methylglyoxal than glyoxal, mouse DJ-1 convert glyoxal more efficiently. Significant decrease in L-lactate level was observed in DJ-1 knockout mice brain, which reveals mouse DJ-1 really perform glyoxalase function within organism. Accumulated MG-H1, one of the advanced glycation end products, was observed in 28-month old male mice heart, liver, and brain extract. Stereotaxic injection of methylglyoxal and glyoxal into the SNpc or dorsal striatum was performed, and reduced TH-positive neuron in both the SNpc and striatum was observed. Glyoxal or methylglyoxal injected mice showed unexpected behavior. There mice showed more activity during few weeks after surgery and spontaneous rotation, underlying mechanism need to be further studied.