The SUMO protease SENP5 is required to maintain mitochondrial morphology and function

Area of Science:

• Mitochondrial biology and dynamics
• Post-translational modifications (SUMOylation)
• Cellular metabolism and oxidative stress

Background:

• Mitochondria are crucial dynamic organelles involved in metabolic stability through fission and fusion.
• Mitochondrial fission GTPase DRP1 is a known substrate for SUMOylation, a post-translational modification.
• The precise role of SUMOylation in regulating mitochondrial dynamics and function requires further investigation.

Purpose of the Study:

• To identify a SUMO protease involved in regulating mitochondrial dynamics.
• To elucidate the role of SENP5 in the SUMOylation of mitochondrial substrates, particularly DRP1.
• To investigate the impact of SENP5 activity on mitochondrial morphology and cellular metabolism.

Main Methods:

• Investigated the catalytic activity of cytosolic SENP5 on SUMO1-modified mitochondrial proteins.
• Utilized overexpression and silencing (RNA interference) of SENP5 to assess its effects on mitochondrial morphology.
• Analyzed DRP1 SUMOylation status and reactive oxygen species (ROS) production under varying SENP5 levels.
• Employed dominant-interfering DRP1 expression and DRP1 RNA silencing to rescue observed phenotypes.

Main Results:

• SENP5 was identified as a key protease that cleaves SUMO1 from mitochondrial substrates.
• SENP5 overexpression rescued SUMO1-induced mitochondrial fragmentation, partly by regulating DRP1.
• SENP5 silencing led to mitochondrial fragmentation, increased DRP1 SUMOylation, and elevated ROS production.
• Restoring mitochondrial tubule formation via DRP1 manipulation rescued SENP5-deficiency-induced defects.

Conclusions:

• SENP5 is a novel regulator of SUMO1 proteolysis targeting mitochondrial proteins.
• SENP5 activity is critical for maintaining mitochondrial morphology and metabolic homeostasis.
• Dysregulation of SENP5 impacts mitochondrial dynamics, leading to increased oxidative stress.