Pharmacological rescue of carnitine transport in primary carnitine deficiency

Area of Science:

• Genetics and Molecular Biology
• Biochemistry
• Cell Biology

Background:

• Primary carnitine deficiency is a genetic disorder affecting carnitine transport.
• It results from mutations in the SLC22A5 gene, which encodes the OCTN2 carnitine transporter.
• Understanding mutation mechanisms is crucial for developing therapies.

Purpose of the Study:

• To investigate the mechanisms by which SLC22A5 mutations impair carnitine transport.
• To identify potential pharmacological interventions for primary carnitine deficiency.

Main Methods:

• Mutational analysis was performed on eight new families with primary carnitine deficiency.
• The OCTN2 transporter was tagged with green fluorescent protein and expressed in CHO cells.
• Confocal microscopy was used to analyze transporter localization and maturation.
• The efficacy of drugs like phenylbutyrate, curcumin, verapamil, and quinidine was tested.

Main Results:

• Several missense OCTN2 mutations allowed normal maturation to the plasma membrane.
• Other mutations led to significant retention of the OCTN2 transporter in the cytoplasm, preventing plasma membrane maturation.
• Phenylbutyrate, quinidine, and verapamil partially stimulated carnitine transport in affected cells.
• Curcumin showed no significant effect on carnitine transport.

Conclusions:

• OCTN2 mutations can impair carnitine transport by disrupting transporter maturation and plasma membrane localization.
• Pharmacological agents, including phenylbutyrate, quinidine, and verapamil, show potential in partially restoring the function of mutant OCTN2 transporters.
• These findings suggest a therapeutic strategy for primary carnitine deficiency by targeting protein maturation defects.