Protective role of glutathione peroxidase GPX-7 in Caenorhabditis elegans models of protein aggregation.

Resumen

Motivation: Ferroptosis is a regulated form cell death caused by an iron-dependent increase in lipid peroxidation of
polyunsatured fatty acid (PUFA) of the plasma membrane. Glutathione peroxidases (GPx's) are a family of enzymes that catalyze
the reduction of H2O2 and lipid peroxides using glutathione (GSH) as a cofactor. PUFAs peroxide reduction by glutathione
peroxidase 4 (GPX4) is the main pathway in mammals protecting against ferroptotic cell death (1). The objective of this research
is to characterize the role of C. elegans GPX-7, an orthologue of mammalian GPX4, in the protection against protein aggregates
formation, which we have found sensitizes C.: elegans to ferroptosis.
Methods: By genetic manipulation and crossing in C. elegans, we have created a number of different mutant strains lacking
gpx-1, gpx-2, gpx-6 and gpx-7, the four orthologues of mammalian GPX4. These mutant strains were crossed with animals
expressing the fusion protein Q40::YFP that forms fluorescent aggregates in muscle cells (2). We quantified these aggregates
using a fluorescence microscope. We also used the glutathione depletor diethylmaleate (DEM) to study the impact of glutathione
homeostasis in these strains (3). Moreover, we have created a mutant strain unc-52; gpx-7 to determine the effect of depleting
gpx-7 on the paralysis phenotype displayed by unc-52 mutants (3).
Results: We have that these two mutant strains gpx-1; gpx-2; gpx-6; gpx-7Q40::YFP and gpx-7 Q40::YFP have half number of
aggregates in comparison with Q40::YFP and gpx-1; gpx-2; gpx-6; Q40::YFP control strains. The strains harbouring the gpx-7
mutation are resistant up to 1.5 mM DEM and 2mM DEM, otherwise letal doses in the control of worms. However, unc-52; gpx-
7 worms did not show differential paralysis when compared to unc-52 single mutants.
To complement this work we want to investigate if we could obtain these results in an intestinal polyQ model (Q44::YFP). That
will be an indicative that gpx-7 protects in the poliQ models.
Conclusions: The deletion of gpx-7 appears to decrease the number of Q40::YFP aggregates in worm muscle cells. In contrast,
it does not affect the paralysis of unc-52 mutants.