Phosphorylation of Translation Initiation Factor 2-Alpha in Leishmania donovani under Stress Is Necessary for Parasite Survival

Abstract

The transformation of Leishmania donovani from a promastigote to an amastigote during mammalian host infection displays the immense adaptability of the parasite to survival under stress. Induction of translation initiation factor 2-alpha (eIF2␣) phosphorylation by stress-specific eIF2␣ kinases is the basic stress-perceiving signal in eukaryotes to counter stress. Here, we demonstrate that elevated temperature and acidic pH induce the phosphorylation of Leishmania donovani eIF2␣ (LdeIF2␣). In vitro inhibition experiments suggest that interference of LdeIF2␣ phosphorylation under conditions of elevated temperature and acidic pH debilitates parasite differentiation and reduces parasite viability (P Ͻ 0.05). Furthermore, inhibition of LdeIF2␣ phosphorylation significantly reduced the infection rate (P Ͻ 0.05), emphasizing its deciding role in successful invasion and infection establishment. Notably, our findings suggested the phosphorylation of LdeIF2␣ under H 2 O 2 -induced oxidative stress. Inhibition of H 2 O 2 -induced LdeIF2␣ phosphorylation hampered antioxidant balance by impaired redox homeostasis gene expression, resulting in increased reactive oxygen species accumulation (P Ͻ 0.05) and finally leading to decreased parasite viability (P Ͻ 0.05). Interestingly, exposure to sodium antimony glucamate and amphotericin B induces LdeIF2␣ phosphorylation, indicating its possible contribution to protection against antileishmanial drugs in common use. Overall, the results strongly suggest that stress-induced LdeIF2␣ phosphorylation is a necessary event for the parasite life cycle under stressed conditions for survival.

Leishmania donovani induced Unfolded Protein Response delays host cell apoptosis in PERK dependent manner

“…donovani infections induced ER stress and host PERK phosphorylation mediated UPR in modulating host cell apoptosis, inhibition studies was carried out. For inhibiting PERK mediated UPR response, RAW 267.4 macrophages were pre-treated with GSK2606414, a specific inhibitor of PERK phosphorylation [ 36 , 37 , 38 , 39 , 40 ]; followed by washing before any infection or exposure as it is also effective against Leishmania PERK [ 26 ]. However, GSK2606414 pre-treatment did not affect the parasite entrance as initially at 4 hours, no any significant difference in terms of parasite entrance was observed in the GSK2606414 pre-treated RAW macrophages than untreated/normal one ( S2 Fig ).…”

“…Cultures were allowed to reach stationary phase (5–6 days post inoculation), as determined by growth curve analysis ( S1 Fig ), prior to inoculation into fresh medium. Syrian golden hamsters were used to maintain the infectivity of the clone regularly [ 26 ].…”

Identification of a three miRNA signature as a novel potential prognostic biomarker in patients with bladder cancer

“…In enrichment and function analysis of DAVID database, our results shows that the top of enriched biological process, cellular component and molecular function were protein phosphorylation, cytoplasm and protein binding, respectively. As for protein phosphorylation, many studies have indicated it was closely related to cancer progress [ 24 – 25 ]. For KEGG pathway analysis, the most important signaling pathways was MAPK.…”

Identification of Potential MHC Class-II-Restricted Epitopes Derived from Leishmania donovani Antigens by Reverse Vaccinology and Evaluation of Their CD4+ T-Cell Responsiveness against Visceral Leishmaniasis

“…To study the intrinsic dynamics of atoms and molecules of the top ranked HLA-epitope complexes, molecular dynamics (MD) simulations were conducted using GROMACS v5.0 as described elsewhere ( 45 , 46 ). A GROMOS 54A7 force-field was employed for amino acid interaction with the simulation of a water model by the simple point charge (SPC) method.…”