Investigator: Peter Belenky, Brown University

Mentor: Richard Bennett, Brown University

Scientific Theme: Molecular Toxicology

Abstract: Amphotericin B and other fungicidal antifungals induce significant toxicity in mammalian cells that limit their therapeutic dose. In both fungal and mammalian cells amphotericin B stimulates a progressive cellular death pathway leading to DNA damage and cellular death. Modulating DNA damage in fungal cells can impact antifungal efficacy. In fungi and mammals nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase (sirtuin) activity leads to tighter histone DNA interactions and regulates DNA damage responses. Elevating cellular NAD levels induces NAD-dependent sirtuin activity and inhibits cytotoxicity in fungi and mammals. Preliminary data indicates that providing NAD vitamin precursors inhibits antifungal toxicity. Thus we hypothesize that elevating NAD metabolism boosts sirtuin activity and reduces the impact of fungicide-induced DNA damage. The proposed research will evaluate this hypothesis in two aims. In Aim 1 we will test how innate and induced differences in NAD metabolism impact antifungal treatment and resulting DNA damage in pathogenic yeast. In Aim 2 we will profile the mechanisms of antifungal induced toxicity in human cell lines and we will test the impact of NAD levels and sirloin activity on antifungal-dependent DNA damage. By exploiting innate differences in fungal and mammalian NAD metabolism this work can identify novel therapeutic methodologies that improve antifungal efficacy while reducing toxic side effects.

Human Health Relevance: There is a growing need to develop more effective antifungal therapy due to the persistently high levels of mortality associated with systemic candidiasis and the development of antifungal resistance. Understanding the molecular toxicology of antifungal agents for both the target fungi and the host will help to guide the development of treatments that more effectively use our current arsenal of antifungal agents.