NAD+ repletion improves muscle function in muscular dystrophy and counters global PARylation.

Degenerating muscle—whether from muscular dystrophies, myopathies, or other diseases—loses its mitochondria (the energy supply) and an essential cofactor nicotinamide adenine dinucleotide (NAD⁺), while gaining an extra load of enzymes that use up NAD⁺, as reported by Ryu and colleagues. The resulting loss of NAD⁺ is exacerbated by a drop in NAD⁺ biosynthetic enzymes, such as NAMPT. Restoration of NAD⁺ levels in either mice or worms with disease-like degenerating muscles improved muscle function, a consequence of more mitochondria, more muscle structural proteins, and a decrease in inflammation. The authors suggest that NAD⁺ repletion may be a successful therapeutic approach for a number of muscle-wasting diseases.