(A) DRP1 re-localizes from the cytosol to the OMM by binding to a docking
protein, MFF. Once at the OMM, DRP1 associates with Zip1, which promotes the
entry of Zn2+ into the matrix via a MCU-dependent manner. The
mechanism by which DRP1 activates Zip1 to stimulate MCU activity remains
unclear. There are two proposed outcomes from this pathway (B and C).
(B) Upon Zn2+ entry into mitochondria, components of the
electron transport chain are inhibited, resulting in decreased
ΔΨM. Normal mitochondrial
function (e.g., responsive changes to nuclear-mitochondrial signaling to
re-establish ΔΨM) allows for the rapid
recovery of ΔΨM and protection against
mitophagy.
(C) Alternatively, Zn2+-induced inhibition of
ΔΨM is not repaired, and the
mitochondrion is destined for mitophagy. This mechanism may identify distinct
organelles or regions of the mitochondrial network that fail to recover from
bioenergetic stress due to aberrations in mitochondrial gene expression,
coordinated nuclear-mitochondrial signaling, or compromised electron transport
chain assembly.