Leishmania donovani chaperonin TCP1γ subunit protects miltefosine induced oxidative damage

Epsilon subunit of T-complex protein-1 from Leishmania donovani: A tetrameric chaperonin

The cytosolic T-complex protein-1 ring complex (TRiC), also referred as chaperonin containing TCP-1(CCT), comprising eight different subunits stacked in double toroidal rings, binds to around 10 % of newly synthesized polypeptides and facilitates their folding in ATP dependent manner. In Leishmania, among five subunits of TCP1 complex, identified either by transcriptome or by proteome analysis, only LdTCP1γ has been well characterized. It forms biologically active homo-oligomeric complex and plays role in protein folding and parasite survival. Lack of information regarding rest of the TCP1 subunits and its structural configuration laid down the necessity to study individual subunits and their role in parasite pathogenicity. The present study involves the cloning, expression and biochemical characterization of TCP1ε subunit (LdTCP1ε) of Leishmania donovani, the causative agent of visceral leishmaniasis. LdTCP1ε exhibited significant difference in primary structure as compared to LdTCP1γ and was evolutionary close to LdTCP1 zeta subunit. Recombinant protein (rLdTCP1ε) exhibited two major bands of 132 kDa and 240 kDa on native-PAGE that corresponds to the dimeric and tetrameric assembly of the epsilon subunit, which showed the chaperonin activity (ATPase and luciferase refolding activity). LdTCP1ε also displayed an increased expression upto 2.7- and 1.8-fold in the late log phase and stationary phase promastigotes and exhibited majorly vesicular localization. The study, thus for the first time, provides an insight for the presence of highly diverge but functionally active dimeric/tetrameric TCP1 epsilon subunit in Leishmania parasite.

Genomic Insight of Leishmania Parasite: In-Depth Review of Drug Resistance Mechanisms and Genetic Mutations

Leishmaniasis, which is caused by a parasitic protozoan of the genus Leishmania, is still a major threat to global health, impacting millions of individuals worldwide in endemic areas. Chemotherapy has been the principal method for managing leishmaniasis; nevertheless, the evolution of drug resistance offers a significant obstacle to therapeutic success. Drug-resistant behavior in these parasites is a complex phenomenon including both innate and acquired mechanisms. Resistance is frequently related to changes in drug transportation, drug target alterations, and enhanced efflux of the drug from the pathogen. This review has revealed specific genetic mutations in Leishmania parasites that are associated with resistance to commonly used antileishmanial drugs such as pentavalent antimonials, miltefosine, amphotericin B, and paromomycin, resulting in changes in gene expression along with the functioning of various proteins involved in drug uptake, metabolism, and efflux. Understanding the genetic changes linked to drug resistance in Leishmania parasites is essential for creating approaches for tackling and avoiding the spread of drug-resistant variants. Based on which specific treatments focus on mutations and pathways could potentially improve treatment efficacy and help long-term leishmaniasis control. More study is needed to uncover the complete range of genetic changes generating medication resistance and to develop new therapies based on available information.

Tat-CCT2 Protects the Neurons from Ischemic Damage by Reducing Oxidative Stress and Activating Autophagic Removal of Damaged Protein in the Gerbil Hippocampus

CCT2 is a eukaryotic chaperonin TCP-1 ring complex subunit that mediates protein folding, autophagosome incorporation, and protein aggregation. In this study, we investigated the effects of CCT on oxidative and ischemic damage using in vitro and in vivo experimental models. The Tat-CCT2 fusion protein was efficiently delivered into HT22 cells in a concentration- and time-dependent manner, and the delivered protein was gradually degraded in HT22 cells. Incubation with Tat-CCT2 significantly ameliorated the 200 µM hydrogen peroxide (H2O2)-induced reduction in cell viability in a concentration-dependent manner, and 8 µM Tat-CCT2 treatment significantly alleviated H2O2-induced DNA fragmentation and reactive oxygen species formation in HT22 cells. In gerbils, CCT2 protein was efficiently delivered into pyramidal cells in CA1 region by intraperitoneally injecting 0.5 mg/kg Tat-CCT2, as opposed to control CCT2. In addition, treatment with 0.2 or 0.5 mg/kg Tat-CCT2 mitigated ischemia-induced hyperlocomotive activity 1 d after ischemia and confirmed the neuroprotective effects by NeuN immunohistochemistry in the hippocampal CA1 region 4 d after ischemia. Tat-CCT2 treatment significantly reduced the ischemia-induced activation of astrocytes and microglia in the hippocampal CA1 region 4 d after ischemia. Furthermore, treatment with 0.2 or 0.5 mg/kg Tat-CCT2 facilitated ischemia-induced autophagic activity and ameliorated ischemia-induced autophagic initiation in the hippocampus 1 d after ischemia based on western blotting for LC3B and Beclin-1, respectively. Levels of p62, an autophagic substrate, significantly increased in the hippocampus following treatment with Tat-CCT2. These results suggested that Tat-CCT2 exerts neuroprotective effects against oxidative stress and ischemic damage by promoting the autophagic removal of damaged proteins or organelles.

Unraveling of interacting protein network of chaperonin TCP1 gamma subunit of Leishmania donovani

T-complex polypeptide-1 (TCP1) is a group II chaperonin that folds various cellular proteins. About 10% of cytosolic proteins in yeast have been shown to flux through the TCP1 protein complex indicating that it interacts and folds a plethora of substrate proteins that perform essential functions. In Leishmania donovani, the gamma subunit of TCP1 (LdTCP1γ) has been shown to form a homo-oligomeric complex and exhibited ATP-dependent protein folding activity. LdTCP1γ is essential for the growth and infectivity of the parasite. The interacting partners of L. donovani TCP1γ, involved in many cellular processes, are far from being understood. In this study, we utilized co-immunoprecipitation assay coupled with liquid chromatography-mass spectrometry (LC-MS) to unravel protein-protein interaction (PPI) networks of LdTCP1γ in the L. donovani parasite. Label-free quantification (LFQ) proteomic analysis revealed 719 interacting partners of LdTCP1γ. String analysis showed that LdTCP1γ interacts with all subunits of TCP1 complex as well as other proteins belonging to pathways like metabolic process, ribosome, protein folding, sorting, and degradation. Trypanothione reductase, identified as one of the interacting partners, is refolded by LdTCP1γ. In addition, the differential expression of LdTCP1γ modulates the trypanothione reductase activity in L. donovani parasite. The study provides novel insight into the role of LdTCP1γ that will pave the way to better understand parasite biology by identifying the interacting partners of this chaperonin.

Immunological characterization of rLdTCP1γ for its prophylactic potential against visceral leishmaniasis in hamster model

Visceral leishmaniasis (VL) is a chronic tropical disease responsible for devastating epidemics worldwide. Though current treatment relies on drugs, the emergence of resistance, toxic side-effects, and strenuous administration has led to an ineffective remedy. Hence, vaccination remains an alternative and desirable approach for VL control. Though extensive research on anti-leishmanial vaccine candidates has been carried out in past decades, presence of an effective molecule is still missing. In the present study, we have evaluated the immunogenicity and prophylactic potential of a recombinant T-complex protein-1 gamma subunit of L. donovani (rLdTCP1γ), against VL in hamster model. The antigen exhibited in vitro stimulation of lymphoproliferative and NO response in miltefosine and amphotericin B treated hamsters depicting its immunotherapeutic/immunogenic nature. Immunization with rLdTCP1γ revealed a strong protective response against experimental VL as indicated by reduced parasite load in the spleen of immunized group compared to infected control. The immunized animals gained body weight and exhibited significant reduction in the spleen and liver weight as compared to infected controls on days 60, 90, 120 post-challenge. A substantial augmentation of cell-mediated immune response as depicted by an increased lymphocyte proliferation, nitric oxide production, DTH responses and increased levels of IgG2 was observed in rLdTCP1γ immunized hamsters. The Th1 stimulatory potential, imparted by the antigen, was found to be intensified in the presence of adjuvant Bacillus Calmette-Guérin (BCG). The efficacy was further assisted by an upregulated mRNA transcript of Th1 induced cytokines (IL-12, IFN-γ and TNFα) and downregulation of IL-4 and IL-10. The results are thus suggestive of rLdTCP1γ having the potential of a strong vaccine candidate against VL.