Biology subjects

Thakur, R. S.

Publications and source records attributed to Thakur, R. S..

6 recordsLinked to original sources

bioRxiv2026

Pleiotropic antimalarial activities and immunomodulation exhibited by Himalayan Buransh (Rhododendron arboreum) in human and rodent malaria models

Emerging drug resistance against the malaria parasite is worrisome and necessitates the development of novel antimalarials. Himalayan Buransh (Rhododendron arboreum) is a well-known medicinal plant found in the northern states of India. In this study, we observed the pleiotropic antimalarial activities and immunomodulation exhibited by the aqueous extract of Buransh flower (AEBF). AEBF demonstrated significant IC50 values (16-29 {micro}g/ml) against the asexual stages of various P. falciparum strains (3D7, Dd2-chloroquine-resistant and C580Y-artemisinin resistant). The oral administration of AEBF (200 mg/kg) in mice, suppressed [~]80% P. berghei parasitemia, improved mean survival time (MST-23.5 days) and prevented splenomegaly. Notably, the combination of AEBF and artesunate not only cleared primary infection, but also conferred sustained immunity. This immunomodulatory effect, driven by protective IFN-{gamma} resulted in reduced parasitemia during a homologous challenge without the need for further treatment. It is important to highlight the malaria transmission blocking activity of AEBF, resulting in reduced sexual stage male gametocyte exflagellation. Furthermore, the virtual drug screening of selected bioactive constituents from Buransh flower demonstrated potent binding against multiple P. falciparum proteins, suggested a pleiotropic mode of action. Altogether, our results corroborated the first ever evidence of the multistage antimalarial potential of Buransh flower, supported by in vitro cell studies, in vivo rodent malaria model and in silico docking analyses. Based on our studys findings and the traditional use of Buransh juice as a medicinal beverage in Uttarakhand, India, we propose exploring it as an adjunct therapy for drug-resistant malaria, subject to further clinical validation.

pathology↗

bioRxiv2025

Dual Role of Plasmacytoid Dendritic Cells in Humoral and CD8⁺ T Cell Memory Post COVID-19 mRNA Vaccination

The Pfizer-BioNTech coronavirus vaccine (BNT162b2), one of the first nanoparticle-based vaccines approved by the World Health Organisation (WHO), demonstrated 95% efficacy in preventing against Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, the precise mechanism of action underlying its effectiveness remains poorly understood. This study investigated the early immune responses in the draining lymph node (dLN) and its role in mediating antiviral protection following vaccination. Here, we focused on the involvement of antigen-presenting cells (APCs) in adaptive immunity. In this study, we demonstrated that the Pfizer-BioNTech coronavirus vaccine is rapidly transported to the dLN and is primarily captured by leukocytes that initiate the expression of the viral antigenic spike protein. Notably, we demonstrated that plasmacytoid dendritic cells (pDCs) are key orchestrators of the inflammatory and humoral response, as their specific depletion led to impaired antibody production and diminished neutralization capacity. Furthermore, single-cell transcriptomic analysis revealed an interaction between pDCs and CD8+ T cells that facilitates T cell activation. In vivo experiments confirmed that pDCs expressing the viral spike protein directly engage with CD8+ T cells, promoting their differentiation and expansion. Moreover, the absence of pDCs affected the formation of antigen-specific memory T cells. Overall, these findings highlight that pDCs are essential players in mediating both adaptive and humoral responses to the Pfizer-BioNTech coronavirus vaccine, providing insights into the mechanistic functioning of mRNA vaccines and establishing a novel role for pDCs as professional APCs.

immunology↗

bioRxiv2024

Neurodegenerative and neurodevelopmental roles for bulk lipid transporters VPS13A and BLTP2 in movement disorders

BackgroundBridge-like lipid transfer proteins (BLTPs) mediate bulk lipid transport at membrane contact sites. Mutations in BLTPs are linked to both early-onset neurodevelopmental and later-onset neurodegenerative diseases, including movement disorders. The tissue specificity and temporal requirements of BLTPs in disease pathogenesis remain poorly understood. ObjectivesTo determine the age-of-onset and tissue-specific roles of VPS13A and BLTP2 in movement disorder pathogenesis using Drosophila models. MethodsWe generated tissue-specific knockdowns of the VPS13A ortholog (Vps13) and the BLTP2 ortholog (hobbit) in neurons and muscles of Drosophila. We analyzed age-dependent locomotor behavior, neurodegeneration, and synapse development and function. ResultsNeuron-specific loss of the VPS13A ortholog caused neurodegeneration followed by age- onset movement deficits and reduced lifespan, while muscle-specific loss affected only lifespan, revealing neurodegeneration and myopathy as independent comorbidities in VPS13A disease. In contrast, neuronal loss of the BLTP2 ortholog resulted in severe early-onset locomotor defects without neurodegeneration, while muscle loss impaired synaptogenesis and neurotransmission at the neuromuscular junction (NMJ). ConclusionsVPS13A maintains neuronal survival, while BLTP2 orchestrates synaptic development. VPS13A function in muscle does not play a role in movement defects. The phenotypic specificity of BLTP function provides mechanistic insights into distinct disease trajectories for BLTP-associated movement disorders.

neuroscience↗

bioRxiv2024

A genetic and physiological model of renal dysfunction in Lowe syndrome

Lowe syndrome (LS) is an X-linked recessive genetic disorder characterized by renal dysfunction, neurodevelopmental defects, and cataract. The affected gene, OCRL encodes for a polyphosphoinositide 5-phosphatase. OCRL is localized to multiple sub-cellular locations in the endolysosomal system and defects in these organelles have been described in human cells depleted of OCRL. However, the relationship of the endolysosomal defects in OCRL depleted cells to the altered physiology of kidney cells of LS patients has not been completely determined. Here we model the kidney phenotypes of LS using a Drosophila nephrocyte model. Using this model system, we demonstrate that OCRL plays a cell-autonomous role in nephrocyte function. Deletion of the only OCRL ortholog in Drosophila (dOCRL) leads to cell-autonomous defects in larval nephrocyte structure and function. Null mutants of dOCRL (dOCRLKO) show defects in the endolysosomal system of larval nephrocytes that are associated with physiological defects in nephrocyte function. These defects could be rescued by reconstitution with a human OCRL transgene but not with a phosphatase dead version or a human LS patient derived mutation. Overall, this work provides a model system to understand the mechanisms by which the sub-cellular changes from loss of OCRL leads to defects in kidney function in human patients.

cell biology↗

bioRxiv2023

PDZD8 promotes autophagy at ER-Lysosome contact sites to regulate synaptogenesis

Building synaptic connections, which are often far from the soma, requires coordinating a host of cellular activities from transcription to protein turnover, placing a high demand on intracellular communication. Membrane contact sites (MCSs) formed between cellular organelles have emerged as key signaling hubs for coordinating an array of cellular activities. We have found that the endoplasmic reticulum (ER) MCS tethering protein PDZD8 is required for activity-dependent synaptogenesis. PDZD8 is sufficient to drive ectopic synaptic bouton formation through an autophagy-dependent mechanism and required for basal synapse formation when autophagy biogenesis is limited. PDZD8 functions at ER-late endosome/lysosome (LEL) MCSs to promote lysosome maturation and accelerate autophagic flux. Mutational analysis of PDZD8s SMP domain further suggests a role for lipid transfer at ER-LEL MCSs. We propose that PDZD8-dependent lipid transfer from ER to LELs promotes lysosome maturation to increase autophagic flux during periods of high demand, including activity-dependent synapse formation. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=170 SRC="FIGDIR/small/564828v2_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1c6b752org.highwire.dtl.DTLVardef@12d77c3org.highwire.dtl.DTLVardef@11d50corg.highwire.dtl.DTLVardef@ba404f_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

Expanded tRNA methyltransferase family member TRMT9B regulates synaptic growth and function

Nervous system function relies on the formation and function of synaptic connections between neurons. Through a genetic screen in Drosophila for new conserved synaptic genes, we identified CG42261/Fid/ TRMT9B as a negative regulator of synaptogenesis. TRMT9B has been studied for its role as a tumor suppressor in multiple carcinomas and is one of two metazoan homologs of yeast tRNA methyltransferase 9 (Trm9), which methylates tRNA wobble uridines. Members of the expanded family of tRNA methyltransferases are increasingly being associated with neurological disorders and new biochemical functions. Interestingly, whereas Trm9 homolog ALKBH8/CG17807 is ubiquitously expressed, we find that TRMT9B is enriched in the nervous system, including at synapses. However, in the absence of animal models the role of TRMT9B in the nervous system has remained unknown. Here, we generated null alleles of TRMT9B and ALKBH8, and through liquid chromatography-mass spectrometry find that ALKBH8 is responsible for canonical tRNA wobble uridine methylation under basal conditions. In the nervous system, we find that TRMT9B negatively regulates synaptogenesis through a methyltransferase-dependent mechanism in agreement with our modeling studies. Finally, we find that neurotransmitter release is impaired in TRMT9B mutants. Our findings reveal a role for TRMT9B in regulating synapse formation and function, and highlight the importance of the expanded family of tRNA methyltransferases in the nervous system.

neuroscience↗