Deciphering the cellular origins and impact of toxic formaldehyde in mammalian cells

PROJECT SUMMARY Formaldehyde is a well-recognized human genotoxin found commonly in the environment but also produced endogenously in mammalian cells. While environmental exposures to formaldehyde are strictly minimized, recent work has shown that mammalian cells are exposed to quantities of endogenous formaldehyde sufficient to cause cancer and pre-mature aging in children with genetic deficiency in formaldehyde-detoxification enzymes or DNA repair pathways. However, beyond these genetic syndromes, we know very little about the life factors that determine the level of endogenous formaldehyde and its impact on health within the general population. Although several biochemical reactions in the cell can generate formaldehyde, such as by demethylase enzymes, and through spontaneous decomposition of folate, the contribution by these reactions to formaldehyde burden and toxicity in vivo is not characterized. Therefore, the overall objectives of this R35 proposal are to better understand the fundamental biology of endogenous formaldehyde production and toxicity in mammalian cells by 1) identifying the physio-pathological sources of formaldehyde in vivo and define how these pathways can be dysregulated to elevate formaldehyde burden, and 2) dissecting the different mechanisms by which endogenous formaldehyde disrupts cell function. To address these objectives, we have developed an innovative and ultra- sensitive workflow that combines a formaldehyde biosensor with mass spectrometry to detect formaldehyde production in mammalians cell lines and mouse models under basal homeostasis and stressed metabolic states. We will leverage this workflow with metabolic and genetic approaches to identify the metabolic conditions and factors that impact formaldehyde production. In parallel, we have utilized a genome-wide CRISPR screen to highlight novel formaldehyde-sensitizing genes that could reveal novel mechanisms of mammalian formaldehyde-toxicity. Successful outcomes from our research will help to build a framework to understand the key cellular factors that determine endogenous formaldehyde level and the subsequent cellular toxicities that arise. The knowledge gained and novel research tools generated will form the foundation for future studies into how endogenous formaldehyde contributes to human diseases and designing interventions that target formaldehyde to improve health.