Mitochondrial reactive oxygen species modify extracellular vesicles secretion rate

Area of Science:

• Cell Biology
• Biochemistry
• Mitochondrial Biology

Background:

• Extracellular vesicle (EV) secretion is influenced by cellular stress, including hypoxia.
• Reactive oxygen species (ROS) and hypoxia-induced factor (HIF)-1 signaling are implicated in EV production, but their specific roles remain unclear.

Purpose of the Study:

• To investigate the distinct contributions of mitochondrial electron transport chain (ETC) activity and HIF-1 signaling to hypoxia-induced EV secretion.
• To determine the role of ROS in modulating EV secretion rates.

Main Methods:

• Utilized an EV reporter cell line (CD9truc-EGFP) to quantify EV secretion rates.
• Administered HIF-1α stabilizer (roxadustat), ETC stimulant (dichloroacetic acid - DCA), ETC inhibitors (rotenone, antimycin A), antioxidant (TEMPO), and metabolic pathway inhibitors (pitavastatin, 4-nitrobenzoate).
• Manipulated mitochondrial ETC activity and ROS production under normoxic and hypoxic conditions.

Main Results:

• HIF-1α stabilization did not affect EV secretion rate.
• ETC stimulation with DCA significantly increased EV secretion, an effect blocked by rotenone (Complex I inhibitor) and TEMPO (antioxidant).
• Inhibition of ETC Complex III mimicked hypoxia and increased ROS-dependent EV secretion, further supported by metabolic pathway interventions.

Conclusions:

• Mitochondrial ETC activity, specifically ROS production, is a key driver of increased EV secretion under simulated hypoxic conditions.
• Hypoxia-mimetics targeting the ETC can modulate EV secretion, highlighting ROS as a potent stimulus for EV release.