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  • Elevated methylglyoxal levels also contribute to carbonyl st

    2021-10-13

    Elevated methylglyoxal levels also contribute to carbonyl stress, cytotoxicity, DNA damage, apoptosis and cell death. These mechanisms may be important for normal aging of the nervous system as well as for the development of neurodegenerative diseases such as Alzheimer's and Parkinson's disease where high AGE levels have been detected in their respective lesions [4], [10], [14]. On the other hand, maximizing the residual activity of glyoxalase I with compounds, which increase glutathione levels such as thiol-based antioxidants including N-acetylcysteine and lipoic ezh2 inhibitor [16], may be a valuable strategy to minimize dicarbonyl levels and their damaging consequences in aging tissue.
    Acknowledgements
    Pancreatic ductal adenocarcinoma (PDAC) is one of the most frequent gastrointestinal cancers and the 4 leading cause of cancer related death. Despite of several new developed anti-cancer drugs, the survival rates in advanced stages remain disappointing. Thus, innovative therapeutic approaches are urgently needed.
    Introduction The glyoxalase system comprises of two enzymes, glyoxalase I and glyoxalase II; and a catalytic amount of reduced glutathione [1]. Glyoxalase I catalyses the conversion of methylglyoxal to d-lactic acid via the intermediate S-lactoylglutathione [2]. Although the glyoxalase system was discovered at the beginning of this century, its exact role in the metabolism remains unclear. Moreover, its widespread distribution and presence in all living organisms suggests that it fulfils a function of fundamental importance [3]. The most accepted hypothesis on the possible role of glyoxalase was proposed by Szent-Gyorgyi et al. [4]. According to this theory, methylglyoxal, known as retine, arrests cell division while glyoxalase I, designated promine, eliminates the aldehyde and thereby initiates cell proliferation. Another hypothesis in favour of linking glyoxalase I with cell division is that S-lactoylglutathione, which plays an important role in the microtubule assembly during mitosis [5], is produced as a result of this enzymatic reaction. Glyoxalase I has been correlated with cell division in various plant systems and serves as a marker for cell proliferation 6, 7, 8, 9, 10, 11. To get insight into the causal relationship between glyoxalase I and rapid cell division, tobacco mesophyll protoplasts were used as they form a highly homogenous population [12]and are well suited for cytofluorimetric analysis [13]. We report here induction of glyoxalase I prior to the initiation of cell division in tobacco mesophyll protoplasts. Glyoxalase I cDNA has been cloned from plants, soybean (EMBL Acc. No. X68819) and tomato [14]. The soybean glyoxalase I has been cloned using antibodies against purified protein from proliferating suspension cells [11]. Although the two sequences appear to be quite different, they share 49.5% nucleotide sequence similarity. The tomato glyoxalase I cDNA was isolated by differential screening of salt-induced genes which showed 20-fold higher enzyme activity in transformed yeast cells as compared to non-transformed cells. It was suggested that glyoxalase I is a stress inducible gene, a concept which was not reported earlier. Very little is known regarding auxin inducible genes involved in the cell division cycle. Few auxin inducible genes have been reported, but the functional protein related to mitotic cycle is not identified in any case [15]. Thus, we report for the first time, activation of glyoxalase I, a functional protein, in auxin induced cell division. Interesting data were revealed when the soybean glyoxalase I cDNA sequence was studied with respect to its functional role.
    Materials and methods
    Results and discussion
    Acknowledgements