Mitochondrial Probe for Glutathione Depletion Reveals NME3 Essentiality for Mitochondrial Redox Response

Maintenance of the mitochondrial thiol redox state is
essential
for cell survival. However, we lack a comprehensive understanding
of the redox response to mitochondrial glutathione depletion. We developed
a mitochondria-penetrating peptide, mtCDNB, to specifically deplete
mitochondrial glutathione. A genome-wide CRISPR/Cas9 screen in tandem
with mtCDNB treatment was employed to uncover regulators of the redox
response to mitochondrial glutathione depletion. We identified nucleoside
diphosphate kinase 3 (NME3) as a regulator of mitochondrial dynamics.
We show that NME3 is recruited to the mitochondrial outer membrane
when under redox stress. In the absence of NME3, there is impaired
mitophagy, which leads to the accumulation of dysfunctional mitochondria.
NME3 knockouts depleted of mitochondrial glutathione have increased
mitochondrial ROS production, accumulate mtDNA lesions, and present
a senescence-associated secretory phenotype. Our findings suggest
a novel role for NME3 in selecting mitochondria for degradation through
mitophagy under conditions of mitochondrial redox stress.