Biology subjects

Rajendran, N. K.

Publications and source records attributed to Rajendran, N. K..

3 recordsLinked to original sources

bioRxiv2026

A Biphasic Effect of Alcohol on Endothelial Plasticity Through Regulation of Endothelial-to-Mesenchymal Transition

BackgroundAlcohol consumption influences cardiovascular disease, but whether it does so by affecting endothelial plasticity is unknown. We tested whether alcohol regulates endothelial-to-mesenchymal transition (EndMT) to influence arterial pathology. MethodsHCAEC and HUVEC were exposed to inflammatory cytokines (TGF{beta} {+/-} IL1{beta}) or hypoxia in the presence of ethanol (0-100 mM). EndMT was assessed by changes in cell marker expression, SNAIL levels, and migration assays. In vivo, carotid ligation was performed in mice gavaged with/without either daily moderate ethanol (2-drink equivalent/d) or episodic binge exposure (7-drink equivalent, 2 days/week) and myo-endothelial cell population assessed. ResultsCytokines and hypoxia induced EndMT in vitro, characterized by loss of endothelial markers, increased mesenchymal markers, elevated SNAIL, and enhanced migratory capacity. Low-to-moderate dose ethanol (5-25 mM) attenuated these changes, preserving endothelial phenotype, whereas high dose ethanol (50-100 mM) either had no effect or exacerbated EndMT. The inhibitory effect of moderate ethanol on cytokine- and hypoxia-induced changes in SMA and Cdh5 expression was abrogated by {gamma}-secretase inhibition, consistent with involvement of Notch signaling. Carotid ligation induced neointimal formation and accumulation of myo-endothelial cells indicative of EndMT. Daily moderate ethanol significantly attenuated neointimal hyperplasia and diminished the myo-endothelial cell population, whereas in contrast, episodic binge ethanol exposure increased pathologic remodeling and myo-endothelial cell abundance. ConclusionsAlcohol modulates endothelial trans-differentiation in a biphasic manner. Low-to-moderate alcohol exposure suppresses EndMT and limits pathological remodeling, whereas binge-level exposure promotes these processes. These findings identify regulation of endothelial plasticity as a potential novel mechanism linking alcohol consumption patterns to vascular disease risk. NEW AND NOTEWORTHYWe identify a previously unrecognized biphasic effect of alcohol on endothelial phenotypic plasticity. Low-to-moderate dose alcohol suppresses endothelial-to-mesenchymal transition (EndMT), whereas high-level (binge) exposure promotes this pro-atherogenic process. Given the central role of EndMT in vascular remodelling and atherosclerosis, these findings provide a mechanistic framework linking alcohol consumption patterns and cardiovascular disease risk - potentially explaining both the protective effect at low/moderate levels, and the detrimental impact of heavy alcohol use. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/718463v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1febae2org.highwire.dtl.DTLVardef@9f5ff1org.highwire.dtl.DTLVardef@153ea69org.highwire.dtl.DTLVardef@42b1ed_HPS_FORMAT_FIGEXP M_FIG C_FIG Injurious stimuli can trigger endothelial cells (EC) to undergo endothelial-to-mesenchymal transition (EndMT) that contributes to arterial remodeling and disease. EndMT is regulated in a biphasic manner by alcohol with low-to-moderate levels (1-3 drink equivalent) suppressing EndMT and attenuating vascular remodeling, whereas higher level/binge exposure (7 drink equivalent) promotes these processes. Graphic created using Biorender.

cell biology↗

bioRxiv2026

Estimation of Protein Melting Temperatures Using Small-Ladder Replica Exchange Simulations

The unfolding or melting temperature (TM) is a central quantity to characterize the stability of proteins and other biopolymers. The accurate prediction of protein melting temperatures by molecular mechanics force field simulations is highly desirable for many biophysical and biotechnological applications. Since the time scales for protein (un-)folding are hardly accessible in conventional MD (cMD) simulations, enhanced sampling techniques such as Temperature Replica Exchange Molecular Dynamics (TREMD) are typically employed. However, TREMD simulations are computationally very demanding especially if large temperature ranges need to be covered. Additionally, if the TM is initially unknown, setting up TREMD simulations is often challenging. To find the optimal initial conditions for such simulations, we describe their performance based on a theoretical model, which we validate on a minimalistic Markov Chain Monte Carlo (MCMC) simulation setup. In an effort to reduce the computational demand, we have investigated the possibility to use small sets of TREMD temperature ladders placed iteratively in the vicinity of a TM estimate. Different TREMD setups were extensively tested on the fast-folding protein Chignolin. We found that appropriate starting conformations lead to significantly faster convergence. Furthermore, we found that, in practice, combining multiple small temperature ladders can be advantageous in comparison to one single temperature ladder. Based on our findings, we formulate practical recommendations on how to set up TREMD for protein melting with optimal efficiency.

biophysics↗

bioRxiv2023

Identification and characterization of intermediate states in mammalian neural crest cell epithelial to mesenchymal transition and delamination

Epithelial to mesenchymal transition (EMT) is a cellular process that converts epithelial cells to mesenchymal cells with migratory potential in both developmental and pathological processes. Although originally considered a binary event, EMT in cancer progression involves intermediate states between a fully epithelial and a fully mesenchymal phenotype, which are characterized by distinct combinations of epithelial and mesenchymal markers. This phenomenon has been termed epithelial to mesenchymal plasticity (EMP), however, the intermediate states remain poorly described and its unclear whether they exist during developmental EMT. Neural crest cells (NCC) are an embryonic progenitor cell population that gives rise to numerous cell types and tissues in vertebrates, and their formation is a classic example of developmental EMT. An important feature of NCC development is their delamination from the neuroepithelium via EMT, following which NCC migrate throughout the embryo and undergo differentiation. NCC delamination shares similar changes in cellular state and structure with cancer cell invasion. However, whether intermediate states also exist during NCC EMT and delamination remains unknown. Through single cell RNA sequencing, we identified intermediate NCC states based on their transcriptional signature and then spatially defined their locations in situ in the dorsolateral neuroepithelium. Our results illustrate the progressive transcriptional and spatial transitions from premigratory to migratory cranial NCC during EMT and delamination. Of note gene expression and trajectory analysis indicate that distinct intermediate populations of NCC delaminate in either S phase or G2/M phase of the cell cycle, and the importance of cell cycle regulation in facilitating mammalian cranial NCC delamination was confirmed through cell cycle inhibition studies. Additionally, transcriptional knockdown revealed a functional role for the intermediate stage marker Dlc1 in regulating NCC delamination and migration. Overall, our work identifying and characterizing the intermediate cellular states, processes, and molecular signals that regulate mammalian NCC EMT and delamination furthers our understanding of developmental EMP and may provide new insights into mechanisms regulating pathological EMP.

developmental biology↗