Defective Mitophagy in XPA via PARP-1 Hyperactivation and NAD+/SIRT1 Reduction
August 30, 2021 3:34:00 PM PDT August 30, 2021 3:34:00 PM PDTth, August 30, 2021 3:34:00 PM PDT
Authors: Fang EF, Scheibye-Knudsen M, Brace LE, Kassahun H, SenGupta T, Nilsen H, Mitchell JR, Croteau DL, Bohr VA
Mitochondrial dysfunction is a common feature in neurodegeneration and aging. We identify mitochondrial dysfunction in xeroderma pigmentosum group A (XPA), a nucleotide excision DNA repair disorder with severe neurodegeneration, in silico and in vivo. XPA-deficient cells show defective mitophagy with excessive cleavage of PINK1 and increased mitochondrial membrane potential. The mitochondrial abnormalities appear to be caused by decreased activation of the NAD(+)-SIRT1-PGC-1? axis triggered by hyperactivation of the DNA damage sensor PARP-1. This phenotype is rescued by PARP-1 inhibition or by supplementation with NAD(+) precursors that also rescue the lifespan defect in xpa-1 nematodes. Importantly, this pathogenesis appears common to ataxia-telangiectasia and Cockayne syndrome, two other DNA repair disorders with neurodegeneration, but absent in XPC, a DNA repair disorder without neurodegeneration. Our findings reveal a nuclear-mitochondrial crosstalk that is critical for the maintenance of mitochondrial health.