UNSW researchers have identified a critical step in the molecular process that allows cells to repair damaged DNA – and it could mean big things for the future of anti-ageing drugs, childhood cancer survivors and even astronauts. It could lead to a revolutionary drug that actually reverses ageing, improves DNA repair and could even help NASA get its astronauts to Mars.
Their experiments in mice suggest a treatment is possible for DNA damage from ageing and radiation. It is so promising it has attracted the attention of NASA, which believes the treatment can help its Mars mission.
While our cells have an innate capability to repair DNA damage − which happens every time we go out into the sun, for example – their ability to do this declines as we age.
The scientists identified that the metabolite NAD+, which is naturally present in every cell of our body, has a key role as a regulator in protein-to-protein interactions that control DNA repair.
Treating mice with a NAD+ precursor, or “booster,” called NMN improved their cells’ ability to repair DNA damage caused by radiation exposure or old age.
“The cells of the old mice were indistinguishable from the young mice, after just one week of treatment,” said lead author Professor David Sinclair of UNSW School of Medical Sciences and Harvard Medical School Boston.
Human trials of NMN therapy will begin within six months.
“This is the closest we are to a safe and effective anti-aging drug that’s perhaps only three to five years away from being on the market if the trials go well,” says Sinclair, who maintains a lab at UNSW in Sydney.
An anti-ageing pill could be on the horizon
For the past four years, Professor Sinclair and Dr Wu have been working on making NMN into a drug substance with their companies MetroBiotech NSW and MetroBiotech International.
The human trials will begin this year at Brigham and Women’s Hospital, in Boston.
The findings on NAD+ and NMN add momentum to the exciting work the UNSW Laboratory for Ageing Research has done over the past four years.
They’ve been looking at the interplay of a number of proteins and molecules and their roles in the ageing process.
They had already established that NAD+ could be useful for treating various diseases of ageing, female infertility and also treating side effects of chemotherapy.
In 2003, Professor Sinclair made a link between the anti-ageing enzyme SIRT1 and resveratrol, a naturally occurring molecule found in tiny quantities in red wine.
“While resveratrol activates SIRT1 alone, NAD+ boosters activate all seven sirtuins, SIRT1-7, and should have an even greater impact on health and longevity,” he says.
NAD+ binding modulates protein interactions
An unexpected function of the oxidized form of nicotinamide adenine dinucleotide (NAD+) could underlie some effects of aging and propensity to age-related diseases. Li et al. found that the protein DBC1 (deleted in breast cancer 1) contains a domain that specifically binds NAD+. Binding of NAD+ inhibited the interaction of DBC1 with PARP1 [poly(adenosine diphosphate–ribose) polymerase 1], an enzyme important in DNA repair. Activity of PARP1 is inhibited by interaction with DBC1. Thus, the reduced abundance of NAD+ associated with aging may decrease PARP1 activity by promoting the interaction of PARP1 with DBC1. This mechanism could help explain the reported rejuvenating actions of NAD+ supplementation in older animals.
Science, March 24 issue p. 1312
DNA repair is essential for life, yet its efficiency declines with age for reasons that are unclear. Numerous proteins possess Nudix homology domains (NHDs) that have no known function. We show that NHDs are NAD+ (oxidized form of nicotinamide adenine dinucleotide) binding domains that regulate protein-protein interactions. The binding of NAD+ to the NHD domain of DBC1 (deleted in breast cancer 1) prevents it from inhibiting PARP1 [poly(adenosine diphosphate–ribose) polymerase], a critical DNA repair protein. As mice age and NAD+ concentrations decline, DBC1 is increasingly bound to PARP1, causing DNA damage to accumulate, a process rapidly reversed by restoring the abundance of NAD+. Thus, NAD+ directly regulates protein-protein interactions, the modulation of which may protect against cancer, radiation, and aging.
SOURCES- USNW, Science