Ferroptosis is a recently described form of regulated cell death characterised by
the iron-dependent generation of lethal amounts of lipid reactive oxygen species
(ROS). Therefore, iron import is an essential process for the execution of
ferroptosis. Iron uptake via transferrin receptor endocytosis is dependent on the
GTPases dynamin 1 and 2. Indeed, the dynamin 1 and 2 inhibitor dynasore, can
protect from ischemia/reperfusion injury, a type of tissue damage that has been
shown to be also blocked by the ferroptosis inhibitor ferrostatin-1. Yet, it is
unknown whether the regulation of iron uptake by dynamin 1 and 2 is essential
for the execution of ferroptosis. A second characteristic hallmark of ferroptosis is
the accumulation of ROS. Mitochondria play a central role in the generation of
ROS through oxidative phosphorylation (OXPHOS). Importantly, experimental
induction of ferroptosis was shown to induce mitochondrial fragmentation and
mitochondrial ROS. Morphological changes of mitochondria are mainly regulated
by another member of the dynamin family of GTPases, dynamin-related protein
1 (Drp1). Interestingly, heterozygous drp1 knockout mice show defective
mitochondrial fission and low levels of lipid ROS in tissues. Yet, how
mitochondrial events are regulated during ferroptosis, including a potential role of
Drp1, have remained unexplored. The aim of this study was to investigate
potential roles for the dynamin family members dynamin 1, 2 and Drp1 in the
regulation of the ferroptosis pathway and to elucidate underlying molecular
mechanisms. Surprisingly, while the dynamin 1 and 2 inhibitor dynasore
efficiently blocked ferroptosis induction, silencing of its main molecular targets
dynamin 1 and 2 was not sufficient to block ferroptosis. Instead, in cell free
systems, dynasore showed radical scavenger properties and acted as a broadly
active antioxidant. Moreover, we found that Drp1 translocates to mitochondria
and promotes cysteine-deprivation induced (CDI) ferroptosis. Of note, we
observed Drp1 to be phosphorylated upon induction of ferroptosis in a manner
dependent on CaMKIIα. Collectively, these data propose that dynasore can
function as a highly active inhibitor of ROS-driven types of cell death via
combined modulation of the iron pool and inhibition of general ROS. On the other
hand, our data reveal that dynamin 1 and 2 silencing is insufficient to regulate
ferroptosis execution. Furthermore, we have reported a key role of Drp1 in the regulation of mitochondrial fragmentation in CDI ferroptosis. These findings
contribute towards our understanding of the ferroptosis pathway, as well as its
implication in the physiopathology of diseases associated with this type of cell
death
