Artificial food sweetener aspartame induces stress response in model organism Schizosaccharomyces pombe

Yilmazer, M.; Bayrak, B.; Palabiyik, B.

Artificial food sweetener aspartame induces stress response in model organism Schizosaccharomyces pombe

2020

Yilmazer, M. | Bayrak, B. | Palabiyik, B.

Aspartame (APM) is a non-nutritive artificial sweetener that has been widely used in many products since 1981. Molecular studies have found that it alters the expression of tumour suppressor genes and oncogenes, forms DNA-DNA and DNA-protein crosslinks, and sister chromatid exchanges. While these results confirm that aspartame is a carcinogenic substance, other studies have failed to detect any negative effect. The present work was aimed to reveal the molecular mechanisms of APM’s effects in the simpler model organism, Schizosaccharomyces pombe, which has cellular processes similar to those of mammals. The human HP1 (heterochromatin protein 1) family ortholog swi6 was selected for the evaluation because swi6 expression is downregulated in cancer cells. Swi6 is a telomere, centromere, and mating-type locus binding protein which regulates the structure of heterochromatin. To verify whether the carcinogenic effects of APM are linked with Swi6, S. pombe parental and swi6Δ strains were analysed through a number of tests, including cell viability, intracellular oxidation, glucose consumption, nucleus DAPI (4',6-diamidino-2-phenylindole) staining, and quantitative real time polymerase chain reaction (qRT-PCR) methods. Based on the results, the S. pombe parental strain adapts to APM effects by activating the stress response pathway, while swi6Δ did not show a meaningful response. Thus, it is proposed that there is a relationship between APM and Swi6, and that APM may be carrying out its effects through Swi6. Nevertheless, it is understood that aspartame is not an effective carcinogenic agent since its effects are weak when compared with the swi6Δ phenotype.

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