Mitochondrially targeted compounds and their impact on cellular bioenergetics

Area of Science:

• Mitochondrial Biology
• Cellular Bioenergetics
• Pharmacology

Background:

• Mitochondria are key targets for treating chronic diseases, with organelle-directed therapeutics under development.
• Triphenylphosphonium (TPP+) conjugates are used to deliver molecules to mitochondria.
• Mitochondrially targeted antioxidants are employed in research, but often at higher concentrations in vitro than in vivo.

Purpose of the Study:

• To investigate the effects of TPP+-conjugated antioxidants (MitoQ, MitoTempol, MitoE) on mesangial cell bioenergetics.
• To compare these effects with TPP+-conjugated compounds lacking antioxidant properties.
• To determine if the TPP+ moiety or the antioxidant group primarily influences mitochondrial function.

Main Methods:

• Cell culture of mesangial cells.
• Treatment with TPP+-conjugated antioxidants (MitoQ, MitoTempol, MitoE) and TPP+-conjugated controls.
• Assessment of cellular bioenergetics, focusing on oxidative phosphorylation.

Main Results:

• All TPP+-containing compounds inhibited oxidative phosphorylation to varying degrees.
• Inhibition was independent of the antioxidant functional groups present.
• The TPP+ moiety demonstrated disruptive effects on mitochondrial function at commonly used in vitro concentrations.

Conclusions:

• The TPP+ moiety can independently impair mitochondrial function at concentrations frequently used in cell culture studies.
• The observed effects are dependent on the linker group connecting TPP+ to the molecule, not the antioxidant properties.
• TPP+ alone is unlikely to account for the protective effects of targeted compounds observed in vivo at lower concentrations.