title: Glutathione-deficient Plasmodium berghei parasites exhibit growth delay and nuclear DNA damage.
abstract: Plasmodium parasites are exposed to endogenous and exogenous oxidative stress during their complex life cycle. To minimize oxidative damage, the parasites use glutathione (GSH) and thioredoxin (Trx) as primary antioxidants. We previously showed that disruption of the Plasmodium berghei gamma-glutamylcysteine synthetase (pbggcs-ko) or the glutathione reductase (pbgr-ko) genes resulted in a significant reduction of GSH in intraerythrocytic stages, and a defect in growth in the pbggcs-ko parasites. In this report, time course experiments of parasite intraerythrocytic development and morphological studies showed a growth delay during the ring to schizont progression. Morphological analysis shows a significant reduction in size (diameter) of trophozoites and schizonts with increased number of cytoplasmic vacuoles in the pbggcs-ko parasites in comparison to the wild type (WT). Furthermore, the pbggcs-ko mutants exhibited an impaired response to oxidative stress and increased levels of nuclear DNA (nDNA) damage. Reduced GSH levels did not result in mitochondrial DNA (mtDNA) damage or protein carbonylations in neither pbggcs-ko nor pbgr-ko parasites. In addition, the pbggcs-ko mutant parasites showed an increase in mRNA expression of genes involved in oxidative stress detoxification and DNA synthesis, suggesting a potential compensatory mechanism to allow for parasite proliferation. These results reveal that low GSH levels affect parasite development through the impairment of oxidative stress reduction systems and damage to the nDNA. Our studies provide new insights into the role of the GSH antioxidant system in the intraerythrocytic development of Plasmodium parasites, with potential translation into novel pharmacological interventions.
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan 00936-5067, Puerto Rico.
authors.forename: Vivian
authors.initials: V
authors.lastname: Padín-Irizarry
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan 00936-5067, Puerto Rico.
authors.forename: Emilee E
authors.initials: EE
authors.lastname: Colón-Lorenzo
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan 00936-5067, Puerto Rico.
authors.forename: Joel
authors.initials: J
authors.lastname: Vega-Rodríguez
authors.affiliation: Department of Pharmacology and Toxicology, University of Puerto Rico, School of Medicine, San Juan 00936-5067, Puerto Rico.
authors.forename: María Del R
authors.initials: Mdel R
authors.lastname: Castro
authors.affiliation: Department of Radiological Sciences, University of Puerto Rico, School of Medicine, San Juan 00936-5067, Puerto Rico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: González-Méndez
authors.affiliation: Department of Pharmacology and Toxicology, University of Puerto Rico, School of Medicine, San Juan 00936-5067, Puerto Rico.
authors.forename: Sylvette
authors.initials: S
authors.lastname: Ayala-Peña
authors.affiliation: Department of Microbiology and Medical Zoology, University of Puerto Rico, School of Medicine, San Juan 00936-5067, Puerto Rico. Electronic address: adelfa.serrano@upr.edu.
authors.forename: Adelfa E
authors.initials: AE
authors.lastname: Serrano
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics; D004249:DNA Damage / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D055786:Gene Knockout Techniques; D005721:Glutamate-Cysteine Ligase / Q000235:genetics*; D005978:Glutathione / Q000172:deficiency / Q000378:metabolism*; D005980:Glutathione Reductase / Q000235:genetics*; D008018:Life Cycle Stages / Q000235:genetics; D008288:Malaria / Q000188:drug therapy / Q000235:genetics / Q000469:parasitology*; D018384:Oxidative Stress / Q000235:genetics; D010962:Plasmodium berghei / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004272:DNA, Mitochondrial; D013879:Thioredoxins; D005980:Glutathione Reductase; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione
keywords: DNA damage; Glutathione; Growth delay; Malaria; Oxidative stress; Plasmodium berghei; Protein carbonylations