Biology subjects

Gope, A.

Publications and source records attributed to Gope, A..

6 recordsLinked to original sources

bioRxiv2026

AUF1-Engineered Intestinal Organoids Enhance Epithelial Barrier Repair and Mucosal Regeneration in Experimental Colitis

Inflammatory bowel disease (IBD) often involves disrupted intestinal epithelial barrier, but therapies specifically targeting this barrier are limited. We found that downregulated AUF1 (HNRNPD) contributes to defective barrier integrity in ulcerative colitis (UC). Compared to controls, its expression level was decreased and inversely correlated with clinical severity. Knocking down AUF1 in human and mouse colonic organoids led to impaired barrier function, with reduced Occludin and upregulated Claudin-2, mimicking characteristic IBD-associated mucosal alterations. Distinct RNA-binding activity of AUF1 protein isoforms contributed to these changes: p37 stabilized Occludin mRNA and blocked microRNA-122/Ago2-mediated repression, whereas p40 promoted Claudin-2 mRNA degradation via ubiquitin-proteasome pathway. Restoring AUF1 expression in organoids enhanced epithelial properties and, when transplanted into mice with established colitis, accelerated mucosal healing and epithelial regeneration in recipient mice and decreased fibrosis. Our study unravelled a post-transcriptional mechanism important for intestinal homeostasis and demonstrated a concept of using engineered organoids for treating IBD.

molecular biology↗

bioRxiv2026

Lactate promotes IL-8 secretion in human alveolar macrophages through GPR132 and lipid metabolic reprogramming

Alveolar macrophages are the primary lung immune cell. They play a crucial role in both maintenance of tissue homeostasis and the initiation of inflammation, secreting multiple immune mediators including the chemokine interleukin-8 (IL-8). Inflammatory settings are often characterised by tissue hypoxia, increased glycolytic rates and lactate secretion, yet how lactate influences alveolar macrophage function remains unclear. Here we investigated how lactate, once considered a waste-product, shapes alveolar macrophage function. To do so, primary human alveolar macrophages (hAMs) and a combination of flow cytometry, ELISA/Luminex, western blot, light microscopy, bioluminescence resonance energy transfer (BRET) and analysis of publicly available datasets were used to understand the role of lactate in lung pathological environments. We demonstrate that hAMs sense extracellular lactate via the expression of different lactate transporters (e.g. MCT1, MCT4) and receptors (i.e. GPR132). Lactate treatment of hAMs increased IL-8 secretion in a MCT1-dependent manner. Lipid metabolism and lipid droplet formation, as well as direct lactate-driven GPR132 signalling were required for lactate-dependent IL-8 release. Our findings uncover a previously unrecognised dual mechanism by which lactate orchestrates immune regulation in hAMs. Specifically, lactate-driven IL-8 production requires two distinct lactate-driven processes: uptake via MCT1, which reprograms lipid metabolism, and signaling through the lactate receptor GPR132. This functional integration of lactate transport and receptor-mediated signaling provides new mechanistic insight into lactates role in hAM biology and highlights potential targets for therapeutic intervention.

immunology↗

bioRxiv2026

Chromosome axis protein SYCP2 recruits HORMAD2 to enable meiotic synapsis quality control in mice

Faithful chromosome segregation during meiosis depends on accurate recombination and synapsis of homologous chromosomes. These processes are monitored in mammals by checkpoint mechanisms involving the meiotic HORMA-domain proteins HORMAD1 and HORMAD2, which bind unsynapsed chromosome axes and promote activation of the DNA damage-response kinase ATR independently of DNA double-strand breaks (DSBs). However, no mechanism for axis recruitment of HORMAD1 or HORMAD2 had been demonstrated, nor had its role in checkpoint function been tested. We establish that a putative HORMAD-interacting region--the closure motif (CM)--within the chromosome-axis component SYCP2 is selectively required for HORMAD2, but not HORMAD1, localization. Deletion of the SYCP2 CM disrupts SYCP2-HORMAD2 complexes and prevents HORMAD2 axis binding without affecting axis assembly or recombination. Consequently, ATR accumulation and signaling on unsynapsed axes are reduced, and the prophase checkpoint malfunctions in a sexually dimorphic manner--causing aberrant elimination of synapsis-proficient spermatocytes and persistence of asynaptic oocytes. The phenotypes of SYCP2-CM-deficient and HORMAD2-null mice are indistinguishable, establishing the requirement for HORMAD2 axis recruitment in synapsis surveillance. We propose that axial recruitment generates a HORMAD2 scaffold that drives clustering-mediated ATR network activation independently of DSBs, thereby linking chromosome-axis architecture to synapsis quality control in mammalian meiosis.

cell biology↗

bioRxiv2023

Metallo-protease Peptidase M84 from Bacillus altitudinis induces ROS dependent apoptosis in ovarian cancer cells by targeting PAR-1

In pursuit of isolating novel anticancer proteases from environmental microbial isolates, we have purified and identified an extracellular metallo-protease from Bacillus altitudinis named Peptidase M84. This protease selectively triggered apoptosis in human ovarian adenocarcinoma cells (PA-1, SKOV3) and mouse ovarian carcinoma cells (ID8), in addition to exhibiting no significant effect on normal human epithelial ovarian cell (IOSE) and mouse peritoneal macrophage (PEM[FE]) cell viabilities. Protease activated receptor-1 (PAR-1); a GPCR which is reported to be overexpressed in ovarian cancer cells was identified as a novel target of Peptidase M84. We observed that Peptidase M84 induced PAR-1 overexpression along with activating its downstream signalling effectors NF{kappa}B and MAPK to promote excessive reactive oxygen species (ROS) generation in ovarian cancer cells. This disrupted mitochondrial membrane potential, allowed cytosolic release of mitochondrial cytochrome c, increased the Bax (pro-apoptotic) to Bcl-2 (anti-apoptotic) ratio and promoted DNA damage to evoke apoptotic death of the ovarian cancer cells. Peptidase M84 also reduced nuclear ki-67 expression in these malignant cells to render an anti-proliferative role. In in vivo set-up, weekly intraperitoneal administration of Peptidase M84 (12 {micro}g/kg body-weight) in the ID8 mice model significantly diminished ascitic fluid accumulation through induction of oxidative stress, increasing murine survival rates by 60%. Collectively, our in vitro and in vivo findings suggested that Peptidase M84 triggered PAR-1 mediated oxidative stress to act as an apoptosis inducer in ovarian cancer cells. This established Peptidase M84 as a promising drug candidate for receptor mediated targeted-therapy of ovarian cancer. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=158 HEIGHT=200 SRC="FIGDIR/small/556500v2_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@6b0a19org.highwire.dtl.DTLVardef@1640510org.highwire.dtl.DTLVardef@1888b49org.highwire.dtl.DTLVardef@1708114_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Glycyrrhizin, an inhibitor of HMGB1 induces autolysosomal degradation function and inhibits H. pylori infection

Helicobacter pylori a key agent for causing gastric complications is linked with peptic ulcer, gastritis, and in severe cases gastric cancer. In response to infection, host cells stimulate autophagy to maintain cellular homeostasis. However, H. pylori have evolved the ability to usurp the hosts autophagic machinery. High mobility group box1 (HMGB1), an alarmin molecule is a regulator of autophagy and its expression is augmented in gastric cancer and many other cancers. Therefore, this study aims to explore the role of glycyrrhizin (a known inhibitor of HMGB1) in autophagy during H. pylori infection. Human gastric cancer (AGS) cells were infected with H. pylori SS1 strain and further treatment was done with glycyrrhizin. Western blot was used to examine the expression levels of autophagy proteins. Autophagy and lysosomal activity were monitored by immunofluorescence. We have performed knockdown of HMGB1 to verify the effect of glycyrrhizin by siRNA transfection method. H. pylori-infection in vivo C56BL/6 mice model was established and the effect of glycyrrhizin treatment was studied. We found that the autophagy-lysosomal pathway was impaired due to a significant increase in lysosomal membrane permeabilization during H. pylori infection in AGS cells. Subsequently, glycyrrhizin treatment restored the lysosomal membrane integrity, accompanied by an increase in cathepsin B activity and reduction of ROS and inflammatory cytokine IL-8. The recovered lysosomal function enhanced autolysosome formation and concomitantly attenuated the intracellular H. pylori growth by eliminating the pathogenic niche from gastric cells. Additionally, glycyrrhizin treatment inhibited inflammation and improved gastric tissue damages in mice.

microbiology↗

bioRxiv2021

Macrophage cell lines and murine infection by Salmonella Typhi L-form bacteria

Antibiotic resistance of pathogenic bacteria has emerged as a major threat to public health worldwide. While stable resistance due to the acquisition of genomic mutations or plasmids carrying antibiotic-resistance genes is well-established, much less is known about the temporary and reversible resistance induced by antibiotic treatment, such as the one due to treatment with bacterial cell-wall inhibiting antibiotics like ampicillin. Typically, ampicillin concentration in the blood and other tissues gradually increases over time after initiation of the treatment. As a result, the bacterial population is exposed to a concentration gradient of ampicillin. This is different from in vitro drug testing where the organism is exposed to fixed drug concentrations from the beginning till the end. To mimic the mode of antibiotic exposure of microorganisms in the tissues, we cultured the wild type, ampicillin-sensitive Salmonella Typhi Ty2 strain (S. Typhi Ty2) in the presence of increasing concentrations of ampicillin over a period of 14 days. This resulted in the development of a strain that exhibited several features of the so-called L-form of bacteria, such as the absence of cell wall, altered shape and slower growth rate compared with the parental strain. Studies on the pathogenesis of S. Typhi L-form showed efficient infection of the murine and human macrophage cell lines. More importantly, S. Typhi L-form was also able to establish infection in a mouse model to the extent comparable to its parental strain. These results suggested that L-form generation following initiation of antibiotic treatment could lead to drug escape of S. Typhi and direct spread to new cells (macrophages), which sustain the infection. Oral infection by the L-form bacteria underscores the potential of rapid disease transmission through faeco-oral route, highlighting the need for new approaches to decrease the reservoir of infection.

microbiology↗