Novel Targets of Formaldehyde Toxicity in Human Cells

CARLA UMANSKY; HERNAN REINGRUBER; MARCO ADRIÁN SCHEIDEGGER; LUCAS PONTEL

CABA

Simposio; Frontiers In Bioscience 3; 2018

Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck (IBioBA-MPSP)

Formaldehyde (FA) is generated during cellular metabolism and can also be derived from the diet. This molecule can rapidly react with proteins and nucleic acids leading to mutagenesis and disease. To prevent the accumulation of endogenous formaldehyde, cells have evolved a two-tier system that consists of a detoxification enzyme (ADH5) and a DNA repair pathway (Fanconi Anemia). It is unclear whether this mechanism operates in cancer cells. By using CRISPR/Cas9 technology we inactivated the detoxification tier in human colorectal carcinoma cells and demonstrated that cells deficient in ADH5 cannot form tumour-spheroids in low adherence plates. Unexpectedly, these cells do not show accumulation of the DNA damage marker phosphorylated histone H2Ax, which indicates that FA cytotoxicity may not be mediated by DNA damage. To furtherunderstand the mechanism by which FA is poisoning ADH5-deficient cells we analysed alternative targets and found that FA affects the proteasome. A proteasome-associated factor is degraded upon FA treatment of ADH5-deficient cells. This factor localized to both nucleus and cytoplasm and its degradation correlates with the reported accumulation of ubiquitinated proteins in response to FA. We therefore propose that the proteasome is a novel target of FA toxicity with consequencesfor cell health and disease.