5-HT₃ Receptors on Mitochondria Influence Mitochondrial Function

Area of Science:

• Cellular Biology
• Neuroscience
• Mitochondrial Research

Background:

• The 5-hydroxytryptamine 3 (5-HT3) receptor is a ligand-gated cation channel superfamily member.
• While typically found on cell membranes, prior research suggested potential mitochondrial localization of 5-HT3 receptor A subunits.

Purpose of the Study:

• To investigate the distribution of 5-HT3 receptor subunits within intracellular and cell-free mitochondria.
• To determine the functional impact of mitochondrial 5-HT3 receptors on cellular processes.

Main Methods:

• Organelle prediction software analysis.
• Transient transfection of HEK293T cells with tagged 5HT3A and 5HT3E subunits.
• Fluorescence microscopy, cell fractionation, and transmission electron microscopy.
• Assessment of mitochondrial membrane potential and oxygen consumption rates.

Main Results:

• 5-HT3 receptor subunits A and E were localized to the inner mitochondrial membrane.
• These subunits can form heteromeric complexes within mitochondria.
• Mitochondrial A and E subunits influenced membrane potential and oxygen consumption upon serotonin exposure.
• Ondansetron pre-treatment inhibited these effects, confirming receptor involvement.

Conclusions:

• 5-HT3 receptors are present on mitochondria and directly impact mitochondrial function.
• The localization and function of these receptors suggest potential therapeutic implications for conditions involving mitochondrial dysfunction.