Biology subjects

Dhabal, S.

Publications and source records attributed to Dhabal, S..

2 recordsLinked to original sources

bioRxiv2023

Methotrexate-modulated talin-dynamics drives cellular mechanical phenotypes via YAP signalling

Methotrexate is a well-known antineoplastic drug used to prevent cancer aggravation. Despite being a targeted therapeutic approach, its administration comes with the risk of cancer recurrence, plausibly through its proven off-target effect on focal adhesions. Since FA dynamics is dependent on force transmission through its constituent proteins, including talin, methotrexate might affect the mechanical activity of these proteins. Here we have combined single-molecule studies, computational dynamics, cell-based assays, and genomic analysis to unveil the focal adhesion-regulating role of methotrexate central to its effect on talin dynamics and downstream pathways. Interestingly, our single-molecule force spectroscopic study shows that methotrexate modulates the bimodal force distribution of talin in a concentration-dependent manner. Steered molecular dynamics reveal that methotrexate-talin interactions alter talin mechanical stability exposing their vinculin binding sites. Finally, we found that methotrexate-regulated talin-dynamics remodel cancer cell mechanical phenotypes like cell polarity, adhesion, and migration by regulating talin-vinculin association-mediated YAP signaling. These results further correlate with genomic analysis of methotrexate-treated patients, demonstrating its clinical importance. Taken together, these findings disseminate the effects of methotrexate-modulated mechanosensitivity of adhesion proteins on cellular events.

cell biology↗

bioRxiv2020

Structure Specific Neuro-toxicity of α-Synuclein Oligomer

Parkinsons disease (PD) is linked to -synuclein (aS) aggregation and deposition of amyloid in the substantia nigra region of the brain tissues. Recent reports suggested that oligomeric assembly structure could be neurotoxic to neuronal cells. In the current investigation we produced two distinct classes of aS oligomers and link the protein conformation state and stability to neuronal cell toxicity. Natural oligomers (NO) enriched with alpha-helical folds are produced in storage of aS at below -20{degrees}C for 7 days. Induced oligomer (IO), often observed in the aggregation pathway of aS were made incubating the protein solution at 37{degrees}C. Natural oligomers remained stable and did not transform into {beta}-sheet rich amyloid fiber and exhibited higher toxicity (80% cell death) compared to induced oligomers. Natural oligomers were ovular shape and the size ranged between 4-5.5 nm. It maintained significant number ([~] 60%) of residues in -helical conformational space. However, initiation of hydrophobic zipping with beta sheet conformation was evidenced in induced oligomer (IO) and a lesser number residues (45%) remained with preference to -helical secondary structure. Hydrophobic collapse leads the transformation of IO into thermodynamically most stable {beta}-sheet rich amyloid fibril. Molten globule like secondary structure stabilized by H-bonding in natural oligomers caused enhanced stability and cellular toxicity compared to induced oligomer. Thus off-pathway/natural oligomers could be plausible reason of neuronal cell death and possible cause of Parkinsons disease.

biophysics↗