Biology subjects

Kumari, G.

Publications and source records attributed to Kumari, G..

7 recordsLinked to original sources

bioRxiv2026

Continuous In Vitro Propagation of the Human Pathogen Babesia microti in Human Erythrocytes

Withdrawal StatementThe authors have withdrawn this manuscript because follow-up molecular authentication and validation studies of cryopreserved early and later parasite passages identified discordant species-specific PCR signals, including evidence of both Babesia microti and Babesia duncani markers in some archived cultures, indicating that the culture history and the timing of contamination or species overgrowth remain unresolved and may materially affect the conclusions of the study. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

microbiology↗

bioRxiv2024

A first-in-Plasmodium study on tRNA intron splicing endonuclease PfTSEN1 and its substrate expression in clinical stage malaria

Mature tRNAs play critical role in several cellular processes including protein translation, post-translational-modifications and programmed-cell-death. Maturation of pre-tRNAs require removal of 5-leaders, 3-trailers, splicing of introns and addition of conserved 3-terminal CCA sequence. The tRNA splicing mechanism, an essential step in tRNA maturation govern by a tRNA splicing endonuclease. While the existence of functional tRNA splicing endonuclease(s) in Plasmodium falciparum has not been identified, its significance in other eukaryotes suggests a potential role in tRNA splicing event. Our study identified total tRNAs in Plasmodium and characterize a PftRNA splicing endonuclease (annotated as PfTSEN1) recognised recently as a component of ribonucleoprotein (RNP) complex, and synthesized a naphthoquinone derivative as a novel anti-malarial compound ( TSENi) targeting the functional activity of this protein. Enzyme activity assays elucidated that PfTSEN1 catalyses splicing of in vitro transcribed pre-tRNAleu, the expression of which was confirmed during the clinical stages of malaria parasite by RT-PCR. Interestingly, TSENi binds to and inhibits enzymatic activity of PfTSEN1, and showed potent anti-malarial activity against chloroquine-sensitive 3D7 and resistant strains Dd2 of P. falciparum. Overall, our study deliver key knowledge towards the functional role of PftRNA splicing endonuclease, and its inhibitor TSENi as potent anti-malarial.

molecular biology↗

bioRxiv2022

Human malaria parasite cold shock protein plays an essential role in asexual and sexual stage development and presents an excellent druggable target

Cold shock proteins are well characterized in bacteria, plants and humans, however there is no information on their existence and role in malaria parasite. Here, we have delineated the function of a novel cold shock protein of Plasmodium falciparum (Pf) which we have annotated PfCoSP. Our results show that recombinant PfCoSP has both DNA and RNA binding activity, and also interacts with alpha and beta tubulin of Pf. PfCoSP binds with RNA and alpha tubulin simultaneously to form a complex. Expression of PfCoSP was found during asexual blood stages and gametocyte stages of malaria parasite. PfCoSP expression up-regulates many folds upon cold treatment, suggesting its role during hypothermic cold shock. Interestingly, PfCoSP showed binding with human cold shock protein LIN28A inhibitor LI71 that also inhibits PfCSP -alpha/beta tubulin interactions. LI71 showed antimalarial activity against asexual blood stage and gametocyte stage suggesting its multi-stage, transmission-blocking potential. We propose that PfCoSP may form a workbench for translation during cold stress via its interactions with target mRNAs and the cytoskeleton protein tubulin.

molecular biology↗

bioRxiv2022

Sphingosine-1-phosphate regulates Plasmodium histone deacetylase activity and exhibits epigenetic control over cell death and differentiation

Histone deacetylases (HDACs) play a key role in cellular processes by the regulation of gene transcription. This study contributes a novel insight how Plasmodium falciparum HDAC (PfHDAC-1) is regulated by S1P produced by host erythrocyte SphK-1. The binding of S1P with endogenous nuclear extract PfHDAC-1 and recombinant PfHDAC-1 blocks their activity. A significant modulation in transcriptional regulation of P. falciparum HDAC regulated genes resulted upon inhibition of S1P production through blocking of hSphK-1 by clinical SphK-1 inhibitor PF-543. PF-543 led to profound decrease in S1P in the parasites nuclear fraction. The significant modulation of PfHDAC-1 regulated specific candidate genes related to gametocytogenesis, virulence and proliferation was observed in parasite treated with SphK-1 inhibitor, suggesting S1P targets PfHDAC-1 and participates in epigenetic regulation of these key cellular processes. The epigenetic modulation of parasite cell growth and differentiation by host provides a novel approach for the developmenthost-targeted therapeutics.

molecular biology↗

bioRxiv2022

Multistage and transmission-blocking tubulin targeting potent antimalarial discovered from the open access MMV Pathogen Box

Development of resistance to current antimalarial therapies remains a significant source of concern. To address this risk, new drugs with novel targets in distinct developmental stages of Plasmodium parasites are required. In our current work, we have targeted P. falciparum Tubulin (PfTubulin) proteins which represent some of the potential drug targets for malaria chemotherapy. Plasmodial Microtubules play a crucial role during parasite proliferation, growth, and transmission, which render them highly desirable targets for the development of next-generation chemotherapeutics. Towards this, we have evaluated the antimalarial activity of Tubulin targeting compounds received from the Medicines for Malaria Venture (MMV) "Pathogen Box" against the human malaria parasite, P. falciparum (including 3D7, RKL-9 (Chloroquine resistant) and R539T (Artemisinin resistant) strains). At nanomolar concentrations, filtered out compounds exhibited pronounced multistage antimalarial effects across the parasite life cycle, including intra-erythrocytic blood stages, liver stage parasites, gametocytes and ookinetes. Concomitantly, these compounds were found to impede male gamete ex-flagellation, thus showing transmission-blocking potential of these compounds. Target mining of these potent compounds, by combining in silico, biochemical and biophysical assays, implicated PfTubulin as their molecular target, which may possibly act by disrupting microtubule assembly dynamics by binding at the interface of -{beta}Tubulin-dimer. Further, promising ADME profile of the parent scaffold supported its consideration as a lead compound for further development. Thus, our work highlights the potential of targeting PfTubulin proteins in discovering and developing next-generation, multistage antimalarial agents for treating Multi-Drug Resistant (MDR) malaria parasites. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/488926v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@ae9713org.highwire.dtl.DTLVardef@40950forg.highwire.dtl.DTLVardef@1fa34f2org.highwire.dtl.DTLVardef@1aa1cae_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2021

Targeting the artemisinin resistant malaria by repositioning of the anti-Hepatitis C Virus drug Alisporivir

The rapid emergence of P. falciparum-resistant strains raises an urgent need to find new antimalarial drug candidates. This study reports the rational repositioning of the anti-Hepatitis C Virus drug, Alisporivir, a non-immunosuppressive analog of cyclosporin A (CsA) against multiple, drug-resistant strains of P. falciparum. Alisporivir being non-hemolytic has been proven to be a better drug than CsA. Indeed, our study also demonstrated the same. Alisporivir inhibited chloroquine-sensitive parasite growth with an IC50 of 196.6nM. Alisporivir also inhibited the growth of chloroquine-resistant parasites with an IC50 of 422.1nM. Alisporivir exhibited, anti-malarial activity in in vivo. Further, we exploited the Cyclophilins targeting potential of Alisporivir against artemisinin-resistant malaria parasite owing to the fact that PfCyP-19B is one of the genes that is overexpressed in artemisinin-resistant parasite revealed by a population transcriptomic study. Our semiquantitative real-time transcript and immunofluorescence analysis confirmed the overexpression of PfCyP-19B in Artemisinin-resistant P. falciparum (PfKelch13R539T). Artemisinin resistance is attributed to slow clearance of ring stage parasites. Ring survival assay (RSA) is designed to access the potency of compounds on these dormant slow clearing parasites leading to drug resistance. Thus, the potency of Alisporivir against PfKelch13R539T was evaluated by RSA. A 2.5-fold decrease in parasite survival was detected with Alisporivir. Further, combination of Alisporivir with DHA found to potentiate the efficacy of DHA by 4.55-fold. These results support the hypothesis that targeting of resistance mechanism is a potential approach to deal with resistant parasite. Overall, this study demonstrates the rational reposition of Alisporivir against resistant malaria resistance.

microbiology↗

bioRxiv2020

Role of RBC membrane protein palmitoylation in regulation of molecular topology and susceptibility to Plasmodium falciparum invasion

Squeezability of biconcave RBC raises a fundamental query, about, how it can restructure its bendable cytoskeleton for efficient micro-circulation. We report for the first time, the existence of dynamic palmitoylome in RBC composed of 118 palmitoylated proteins that reduced to 42 upon treatment with 2BP, a generic inhibitor of palmitoylation. In-depth analysis revealed that Semaphorin7A, CR1 and ABCB6, the known RBC receptors for P. falciparum were reduced to negligible in 2BP-treated RBCs, suggesting palmitoylation-dependent recruitment of parasite-specific receptors. Interestingly, Kell, a single disulphide-linked co-partner in Kell-Kx complex was undetected in 2BP-treated RBCs, while Kx remained intact. RBCs-blocked with anti-Kell antibody demonstrated signficant reduction in parasite invasion, thus suggesting it as a receptor proto-type for P. falciparum invasion. Finally, reduced expression of Kell in palmitoylated protein pool of sickle-cell RBC ghost, with its diminished surface representation in these RBCs, proposed Kell, as one of the novel receptor-prototype for P. falciparum invasion.

cell biology↗