P-glycoprotein-9-mediated multidrug tolerance in Caenorhabditis elegans

Area of Science:

• Molecular biology
• Parasitology
• Pharmacology

Background:

• P-glycoproteins (PGPs) are key mediators of multidrug resistance.
• In parasitic helminths, resistance to macrocyclic lactones (MLs) is linked to PGP regulation and amphid defects.
• Nuclear hormone receptor (NHR)-8 influences xenobiotic tolerance by regulating PGP genes in Caenorhabditis elegans.

Purpose of the Study:

• To investigate the specific role of PGP-9 in drug efflux in C. elegans.
• To determine if PGP-9 is essential for multidrug tolerance.
• To explore the regulatory relationship between NHR-8 and PGP-9.

Main Methods:

• Utilized an ML-resistant C. elegans strain (IVR10) and a pgp-9 mutant to assess larval development under MLs and tunicamycin (TM).
• Evaluated the impact of pgp-9 deletion on the dye-filling defective (Dyf) phenotype.
• Investigated NHR-8's role in regulating pgp-9 using RT-qPCR and ML sensitivity assays in an IVR10 nhr-8 mutant.

Main Results:

• PGP-9 deletion restored drug sensitivity in the IVR10 strain, irrespective of the Dyf phenotype.
• NHR-8 deletion increased IVM sensitivity but did not significantly alter pgp-9 expression.
• RNAi targeting pgp-9 in nhr-8 mutants further enhanced IVM sensitivity, decoupling PGP-9 from NHR-8 regulation.

Conclusions:

• PGP-9 is directly demonstrated as essential for multidrug tolerance in C. elegans.
• PGP-9 functions independently of amphid structural defects and NHR-8 regulation.
• PGP-9 represents a novel mechanism for drug resistance and a potential therapeutic target for ML treatments.