Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Biochemistry

Supervisor

Dr. J.G. Pickering

Abstract

The ability of vascular cells to withstand oxidative insults is critical to vascular health. NAD+, which drives poly (ADP-ribose) polymerase (PARP) and sirtuin (SIRT) reactions, can be compromised and strategies for overcoming this limitation in the vasculature do not exist. This study determines if nicotinamide riboside (NR) delivery can augment NAD+ stores and fuel resistance to oxidative stress. I established that oxidative-stress insult on vascular cells decreased NAD+ levels, accompanied by a striking increase in nuclear PAR-chain accumulation. PARP inhibition abolished PAR-chain formation and preserved NAD+ levels, establishing PARP in NAD+ consumption in this model. NR delivery protected against cell-shrinkage and cell death and promoted DNA repair efficiency. PARP inhibition mimicked NR’s beneficial effects on cell-shrinkage and viability but at the cost of DNA repair efficiency. Interestingly, the beneficial effects of NR on viability and DNA repair were abrogated upon SIRT1 knock-down (KD). SIRT6 KD was similarly implicated in NR-mediated DNA repair. Furthermore, NR delivery protected against oxidative-stress-induced senescence. This protection was partially lost by SIRT1 KD. NR delivery protects vascular cells from H2O2–induced cell death, cytoskeletal collapse and senescence and promotes DNA repair efficiency. This NAD+ fueling strategy may offer new opportunities for resisting oxidative-stress insults in the aging vasculature.

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