Biology subjects

Rajasekaran, V.

Publications and source records attributed to Rajasekaran, V..

6 recordsLinked to original sources

bioRxiv2026

Cellular uptake of Micro and nano plastics Induces Mitochondrial Dysfunction

Micro and nano plastics (MNPs) have become ubiquitous contaminants in the environment with their occurrence being detected in air, water and food. They can cross biological barriers and slowly build up in different organs, including the placenta, raising concerns about possible impacts on maternal and fetal health. Placenta, a highly metabolically active organ composed primarily of trophoblast cells, requires substantial energy for proper development and function. However, the effects of MNPs exposure on trophoblast biology and mitochondrial health remain poorly understood. This study investigated the in vivo systemic accumulation of MNP in different organs of pregnant mice and their localization within various organelles in vitro. These effects influenced trophoblast energy metabolism and led to reduced migration. Mice received fluorescent polystyrene MNPs via their drinking water. Biodistribution was evaluated in vivo using IVIS whole-body imaging, while ex vivo fluorescence imaging confirmed accumulation of these particles in multiple organs and cells. In parallel, human HTR-8/SVneo trophoblast cells were exposed to MNPs, demonstrating rapid cellular uptake and mitochondrial and nuclear localization via fluorescence microscopy. TEM analysis uncovered mitochondrial structural alterations and the localization of MNPs. Seahorse analysis revealed impaired mitochondrial respiration and oxygen consumption rates, indicating compromised cellular bioenergetics in MNPs-treated cells, which led to inflammation, altered mtDNA copy number, and impaired trophoblast migration. Overall, these findings indicate that pregnant mice exposed to MNPs undergo systemic transfer, with trophoblast uptake marked by mitochondrial dysfunction, inflammation, and reduced migration. Our study identifies mitochondrial dysfunction as a central mechanism underlying MNP-mediated placental toxicity and underscores the potential role of environmental microplastic exposure in adverse pregnancy outcomes. HighlightsO_LICellular uptake of MNPs and their localization across various organelles. C_LIO_LIUptake of MNPs disrupts mitochondrial function and promotes inflammation. C_LIO_LICellular uptake of MNPs impairs cell migration. C_LI

physiology↗

bioRxiv2023

Genetic variation at 11q23.1 confers colorectal cancer risk by dysregulation of colonic tuft cell transcriptional activator POU2AF2

Common genetic variation at 11q23.1 is associated with colorectal cancer (CRC) risk, and exerts local (cis) expression quantitative trait locus (cis-eQTL) effects on POU2AF2, COLCA1 and POU2AF3 genes. However, complex linkage disequilibrium and correlated expression at the 11q23.1 locus has thus far hindered elucidation of the mechanisms by which genetic variants impart CRC risk. Here, we establish that rs3087967 is the likely causal eQTL at this locus, co-localising with expression of POU2AF2 and CRC risk. Furthermore, we show trans-eQTL effects on 21 distant target genes, which are highly enriched for Tuft cell markers. Analysis of available scRNAseq, ChIPseq and scATACseq data implicates POU2AF2 as the primary controller of the tuft cell specific trans-genes through POU2F3-correlated genetic regulation. Immunofluorescence demonstrates that the rs3087967 risk genotype (T) is associated with lower tuft cell abundance in human colonic epithelium. CRISPR-mediated deletion of the 11q23.1 risk locus in the mouse germline exacerbated the ApcMin/+ mouse phenotype upon abrogation of Pou2af2 expression specifically. Taken together, we implicate a key protective role of tuft cells in the large bowel and the importance of mis-regulation of POU2AF2 as the prime tuft cell transcriptional activator at this locus.

genetics↗

bioRxiv2022

Transcriptional dynamics of colorectal cancer risk associated variation at 11q23.1 are correlated with tuft cell abundance and marker expression in silico

Colorectal cancer (CRC) is characterised by heritable risk that is not well understood. Heritable, genetic variation at 11q23.1 is associated with increased colorectal cancer (CRC) risk, demonstrating eQTL effects on 3 cis- and 23 trans-eQTL targets. We sought to determine the relationship between 11q23.1 cis- and trans-eQTL target expression and test for potential cell-specificity. scRNAseq from 32,361 healthy colonic epithelial cells was aggregated and subject to weighted gene co-expression network analysis (WGCNA). One module (blue) included 19 trans-eQTL targets and was correlated with C11orf53 expression only. Following unsupervised clustering of single cells, the expression of 19 trans-eQTL targets was greatest and most variable in cluster number 11, which transcriptionally resembled tuft cells. 14 trans-eQTL targets were found to demarcate this cluster, 11 of which were corroborated in a second dataset. Intra-cluster WGCNA and module preservation analysis then identified twelve 11q23.1 trans-eQTL targets to comprise a network that was specific to cluster 11. Finally, linear modelling and differential abundance testing showed 11q23.1 trans-eQTL target expression was predictive of cluster 11 abundance. Our findings suggest 11q23.1 trans-eQTL targets comprise a C11orf53-related network that is likely tuft cell-specific and reduced expression of these genes correlates with reduced tuft cell abundance in silico.

bioinformatics↗

bioRxiv2021

Minicells from Highly Genome Reduced Escherichia coli: Cytoplasmic and Surface Expression of Recombinant Proteins and Incorporation in the Minicells

Minicells, small cells lacking a chromosome, produced by bacteria with mutated min genes, which control cell division septum placement, have many potential uses. Minicells have contributed to basic bacterial physiology studies and can enable new biotechnological applications, including drug delivery and vaccines. Genome-reduced (GR) bacteria are another informative area of investigation. Investigators identified that with even almost 30% of the E. coli genome deleted, the bacteria still live. In biotechnology and synthetic biology, GR bacteria offer certain advantages. With GR bacteria, more recombinant genes can be placed into GR chromosomes and fewer cell resources are devoted to purposes apart from biotechnological goals. Here, we show that these two technologies can be combined: min mutants can be made in GR E. coli. The minCminD mutant GR E. coli produce minicells that concentrate engineered recombinant proteins within these spherical delivery systems. We expressed recombinant GFP protein in the cytoplasm of GR bacteria and showed that it is concentrated within the minicells. We also expressed proteins on the surfaces of minicells made from GR bacteria using a recombinant Gram-negative AIDA-I autotransporter expression cassette. As some autotransporters, like AIDA-I, are concentrated at the bacterial poles, where minicells bud, and because the surface-to-volume ratio of the small minicells is higher than bacteria, recombinant proteins expressed on surfaces of the GR bacteria are concentrated on the minicells. Minicells made from GR bacteria can enable useful biotechnological innovations, such as drug delivery vehicles and vaccine immunogens.

synthetic biology↗

bioRxiv2021

Killed whole genome-reduced bacteria surface-expressed coronavirus fusion peptide vaccines protect against disease in a porcine model

As the coronavirus disease 2019 (COVID-19) pandemic rages on, it is important to explore new evolution-resistant vaccine antigens and new vaccine platforms that can produce readily scalable, inexpensive vaccines with easier storage and transport. We report here a synthetic biology-based vaccine platform that employs an expression vector with an inducible Gram-negative autotransporter to express vaccine antigens on surface of genome-reduced bacteria to enhance interaction of vaccine antigen with immune system. As a proof of principle, we utilized genome-reduced E. coli to express SARS-CoV-2 and porcine epidemic diarrhea virus (PEDV) fusion peptide (FP) on the cell surface, and evaluated their use as a killed whole cell vaccine. The FP sequence is highly conserved across coronaviruses; the 6 FP core amino acid residues along with the 4 adjacent residues upstream and the 3 residues downstream the core are identical between SARS-CoV-2 and PEDV. We tested the efficacy of PEDV FP and SARS-CoV-2 FP vaccines in a PEDV challenge pig model. We demonstrated that both vaccines induced potent anamnestic responses upon virus challenge, potentiated IFN-{gamma} responses, reduced viral RNA loads in jejunum tissue, and provided significant protection against clinical disease. However, neither vaccines elicited sterilizing immunity. Since SARS-CoV-2 FP and PEDV FP vaccines provided similar clinical protection, the coronavirus FP could be a target for a broadly-protective vaccine using any platform. Importantly, the genome-reduced bacterial surface-expressed vaccine platform, when using a vaccine appropriate bacterial vector, has potential utility as an inexpensive, readily manufactured, and rapid vaccine platform for other pathogens. Significance StatementWe report a new vaccine platform to express vaccine antigens on surface of genome-reduced bacteria to enhance vaccine immunogenicity. We demonstrated the utility of this vaccine platform by expressing the highly conserved fusion peptide (FP) of SARS-CoV-2 and porcine epidemic diarrhea virus on the surface of E.coli to produce killed whole cell bacterial vaccines. The vaccine primes a potent anamnestic response, potentiates IFN-{gamma} responses, and provides significant protection in pigs against disease following virus challenge. The FP could be a target for a broadly-protective coronavirus vaccine since a Betacoronavirus SARS-CoV-2 FP vaccine provided cross-protection against Alphacoronavirus PEDV. When using a vaccine appropriate bacteria vector, this inexpensive new vaccine platform offers the potential for use in developing countries.

microbiology↗

bioRxiv2019

Aspirin-mediated DKK-1 increase rescues Wnt-driven stem-like phenotype in human intestinal organoids

Aspirin reduces the incidence and mortality of colorectal cancer (CRC). Wnt signalling drives CRC development from initiation to progression through regulation of epithelial-mesenchymal transition (EMT) and cancer stem cell populations (CSC). Here, we investigated whether aspirin can rescue these pro-invasive phenotypes associated with CRC progression in Wnt-driven human and mouse intestinal organoids. Aspirin rescues the Wnt-driven cystic organoid phenotype by promoting budding in mouse and human Apc deficient organoids, which is paralleled by decreased stem cell marker expression. Aspirin-mediated Wnt inhibition in ApcMin/+ mice is associated with EMT inhibition and decreased cell migration, invasion and motility in CRC cell lines. Chemical Wnt activation induces EMT and stem-like alterations in CRC cells, which are rescued by aspirin. Aspirin increases expression of the Wnt antagonist Dickkopf-1 (DKK-1) in CRC cells and organoids derived from FAP patients. We provide evidence of phenotypic biomarkers of aspirin response with an increased epithelial and reduced stem-like state mediated by an increase in DKK-1. Thus we highlight a novel mechanism of aspirin-mediated Wnt inhibition and potential phenotypic and molecular biomarkers for trials.

cancer biology↗