Biology subjects

Mandal, S. C.

Publications and source records attributed to Mandal, S. C..

5 recordsLinked to original sources

bioRxiv2025

Azadiradione regulates Heat Shock Factor 1 function by interacting with its DNA-binding domain independent of the oligomerization domain

Heat shock factor 1 (HSF1) masters cellular proteostasis under stress by upregulating the expression of molecular chaperones that help refold or degrade the misfolded proteins. HSF1 activation involves a monomer-to-oligomer transition and binding to its recognition sequence, the heat shock elements (HSEs) on its target gene promoters. HSF1 activity declines with age as well as in neurodegenerative disorders (NDs) such as Parkinsons disease, highlighting the need for strategies to restore its function. Azadiradione (AZD), a limonoid isolated from Azadirachta indica seeds, directly activates HSF1 in cellular and preclinical ND models, unlike other small-molecule activators reported elsewhere. We investigated the molecular basis of AZD-mediated HSF1 activation using purified variants of this protein including those without its oligomerization and transactivation domain. Fluorescence polarization and dynamic light scattering assays revealed that AZD promotes the oligomerization of monomeric HSF1 to enhance its HSE-binding affinity by engaging with its DNA-binding domain (DBD). The oligomerization domain known to be required for stress-induced activation, appears redundant in AZD-mediated activation. Furthermore, evidence suggests AZD-induced conformational alterations in the HSE facilitate its binding to the HSF1 monomer. Notably, AZD reduces the DNA-binding ability of pre-assembled oligomeric HSF1 by triggering its amyloid-like aggregation. This finding also highlighted a potential anticancer effect of AZD, as cancer cells heavily depend on this HSF1 population for rapid proliferation and survival. Overall, these findings offer novel insights into the functional regulation of HSF1 and suggest a framework for developing small-molecule HSF1 activators with therapeutic potential for protein conformation disorders.

biochemistry↗

bioRxiv2025

HSF1 Activator Azadiradione Ameliorates Parkinson Disease and Extends Lifespan in Preclinical Models: Analysis of Underlying Molecular Mechanism

Parkinsons disease (PD) affects millions worldwide, with no efficient therapy currently available. A major cause of the initiation and progression of this degenerative disease is the dysfunctional cellular protein quality control system (PQC), leading to the accumulation of toxic protein aggregates in neurons. We previously reported azadiradione (AZD), a small molecule (MW 451 Da), as a potent inducer of heat shock factor 1 (HSF1) activity, which could alleviate cellular toxicity induced by misfolded proteins by upregulating the levels of inducible molecular chaperones and proteasome activity. Here, we show the multifaceted effect of AZD in enhancing the capacity of PQC machinery in cells, fruit flies, and a PD mouse model. AZD activated HSF1 by promoting its phosphorylation at S326 through MEK. In parallel, AZD boosted protein degradation through increased chymotrypsin-like proteasome activity, upregulation of the ubiquitin ligase CHIP. AZD induced autophagy, marked by elevated levels of Beclin 1, ATG7, and ULK1 phosphorylation at S555, along with mTORC1 inhibition via AMPK activation. Surprisingly, the calorie restriction pathway was also upregulated upon AZD treatment, as demonstrated by the enhanced phosphorylation of FOXO3 and FOXO1, along with increased activity of their target enzymes SOD and catalase. Notably, AKT activity was also suppressed in AZD-treated cells. In vivo, AZD improved motor function, dopaminergic neuron survival, and tyrosine hydroxylase activity in an MPTP-induced mouse model of PD, and extended lifespan in Drosophila without compromising fertility or mobility. These findings highlight AZD as a promising therapeutic candidate for restoring PQC and mitigating PD pathology.

molecular biology↗

bioRxiv2024

Polyphenol-rich fraction of Bergenia ligulata (Wall.) Engl. sensitizes colon and breast cancer metastasis in vivo: Evidence of cell-type specific mechanism

BackgroundColon and breast cancer are one of the leading causes of mortality worldwide. Limited efficacies of present treatments highlighted an urgent need for improvement. Bergenia ligulata is known for its anticancer properties in Indian traditional and folk medicine though the molecular basis of its effects, particularly its anti-metastatic properties, is not well understood. Anti-prostate cancer activity of a LCMS defined polyphenol-rich fraction from Bergenia ligulata (PFBL) rhizome extract has already been published showing promising results in preclinical models. PurposeThe present study aims to explore anti-cancer activity and anti-metastatic potentials of PFBL against colon and breast cancers in both in vitro and preclinical settings. Study design and methodsPFBL alone or in synergy with standard chemotherapeutic drugs was tasted in CT26 and 4T1 subcutaneous solid tumors in BALB/c mice. The effect of PFBL was analyzed in terms of changes in tumor mass and different molecular marker levels. Anti-metastatic potential of PFBL was evaluated in CT26 and 4T1 lung metastasis model in mice focusing on the number of lung nodules and lung size. ResultsOur results evidenced that PFBL efficiently regressed both CT26 and 4T1-induced solid tumors alone and in combination with 5FU/doxorubicin without affecting the health of normal host. Notably, PFBL suppressed lung metastasis of 4T1 and CT26 cells in mice with great efficacy. Analysis of tumor and cell extracts suggested that colon cancer cells died by autophagy, while breast cancer cells majorly died by caspase-dependent apoptosis. PFBL actions involved AMPK-dependent inhibition of mTORC1 and subsequent increase in LC3II, PARP1, CDK4 and Cyclin D1 levels in both HCT116 and MCF7 cells; an elevation of intracellular ROS level was the major cause of death in both the cancer types. PFBL treatment also reversed the EMT marker expressions in in vivo and in vitro. ConclusionPFBL regressed colon and breast cancer metastasis through distinct mechanisms with little effect on healthy mice. The present study underscored PFBL as a novel anti-tumor and anti-metastasis candidate warranting further testing in clinical settings.

cancer biology↗

bioRxiv2021

Immune escape facilitation by mutations of epitope residues in RdRp of SARS-CoV-2

SARS-CoV-2 has considerably higher mutation rate. SARS-CoV-2 possesses a RNA dependent RNA polymerase (RdRp) which helps to replicate its genome. The mutation P323L in RdRp is associated with the loss of a particular epitope (321-327) from this protein which may influence the pathogenesis of the concern SARS-CoV-2 through the development of antibody escape variants. We consider the effect of mutations in some of the epitope regions including the naturally occurring mutation P323L on the structure of the epitope and their interface with paratope using all-atom molecular dynamics (MD) simulation studies. P323L mutations cause conformational changes in the epitope region by opening up the region associated with increase in the radius of gyration and intramolecular hydrogen bonds, making the region less accessible. Moreover, the fluctuations in the dihedral angles in the epitope:paratope (IgG) interface increase which destabilize the interface. Such mutations may help in escaping antibody mediated immunity of the host.

bioinformatics↗

bioRxiv2021

Ovine CD14- an immune response gene has a role against gastrointesinal nematode Haemonchus contortus -a novel report

CD14 (also known as monocyte differentiation antigen) is an important immune response gene known to be primarily responsible for innate immunity against bacterial pathogen and as pattern recognition receptor (PRR) binds with LPS (endotoxin), lipoproteins, lipotechoic acid of bacteria.So far very limited work has been conducted in parasitic immunology. In the current study, we reported the role of CD14 in parasitic immunology in livestock species (sheep) for the first time. Ovine CD14 is characterized as a horse-shoe shaped as a bent solenoid with a hydrophobic amino-terminal pocket for CD14 along with domains. High mutation frequency was observed, out of total 41 mutations identified, 23 mutations were observed to be thermodynamically unstable and 11 mutations were deleterious in nature, causing major functional alteration of important domains of CD14, an indicative for variations in individual susceptibility for sheeps against Haemonchus contortus infestations. In silico studies with molecular docking reveals a role of immune response against Haemonchus contortus in sheep, which is later confirmed with experimental evidence through differential mRNA expression analysis for sheep, which revealed better expression of CD14 in Haemonchus contortus infected sheep compared to that of healthy sheep. We confirmed the above findings with supportive evidences with haematological and biochemical analyses. Phylogenetic analysis was conducted to assess the evolutionary relationship with respect to human and observed that sheep may well be used as model organism due better genetic closeness compared to that of mouse.

genomics↗