Biology subjects

Setu, B.

Publications and source records attributed to Setu, B..

4 recordsLinked to original sources

bioRxiv2025

ETEC heat-labile toxin promotes β-catenin stabilization and transcriptional reprogramming to disrupt intestinal epithelial differentiation

Enterotoxigenic Escherichia coli (ETEC), defined by their production of heat-labile (LT) and heat-stable (ST) enterotoxins, are a common cause of acute diarrheal illness in children from low- and middle-income countries, and are also linked to long-term sequelae such as malnutrition, and growth impairment. While the mechanisms underlying toxin-mediated acute diarrhea are known, the molecular events involved in ETEC related sequelae remain unclear. Here, we demonstrate that the ETEC heat-labile toxin (LT) profoundly remodels intestinal epithelial composition and function through modulation of WNT/{beta}-catenin signaling. Using human ileal enteroids, we demonstrate that LT stabilizes {beta}-catenin independently of WNT ligands, promotes its nuclear accumulation, and enhances TCF/LEF-driven transcription. Single-cell transcriptomic analyses reveal that LT increases intestinal proliferation by enhancing cell cycle activity across all epithelial lineages, thus disrupting epithelial composition by expanding proliferative progenitor populations at the expense of absorptive enterocytes. Simultaneously, LT impairs epithelial maturation and suppresses transcriptional programs required for nutrient absorption and differentiation. Together, these findings identify LT as a potent driver of intestinal epithelial reprogramming, providing mechanistic insight into how ETEC infection may drive long-term consequences beyond acute diarrhea and may inform strategies to prevent major sequelae, including malnutrition, that affect millions of children worldwide.

microbiology↗

bioRxiv2025

Parenteral Vaccination with recombinant EtpA glycoprotein impairs enterotoxigenic E. coli colonization

Enterotoxigenic E. coli (ETEC) cause hundreds of millions of cases of acute diarrheal illness in low-middle income regions, disproportionately in young children. To date there is no licensed, broadly protective vaccine to protect against these common but antigenically heterogeneous pathogens. One of the more highly conserved antigens of ETEC, EtpA, is an extracellular glycoprotein adhesin that preferentially binds to blood group A glycans on intestinal epithelia. EtpA contributes to increased severity of illness in blood group A individuals, elicits robust serologic and fecal antibody responses following infection, and has been associated with protection against subsequent infection. However, its utility as a protective antigen needs further examination. In the present studies we examined whether parenteral vaccination with recombinant EtpA (rEtpA) could afford protection against intestinal colonization in a murine model of ETEC infection. Here, we demonstrate that intramuscular vaccination with rEtpA when adjuvanted with double mutant LT (dmLT) primes IgG predominant mucosal antibody responses to ETEC challenge. Notably, however, both antibody levels and avidity, as well as protection were dependent on vaccination schedule. Likewise, by electron microscopy polyclonal epitope mapping (EMPEM) we observed a greater diversity of epitopes targeted by antibodies after a more protracted vaccination schedule. Next, we explored the utility of IM immunization with alum-adjuvanted rEtpA. This elicited strong serologic and fecal IgG responses. Although accompanied by negligible IgA mucosal responses, EtpA alum-adjuvanted IM vaccination nevertheless protected against ETEC intestinal colonization. Collectively, these data suggest that EtpA could expand the portfolio of antigens targeted in ETEC subunit vaccine development.

microbiology↗

bioRxiv2024

Host-derived CEACAM-laden vesicles engage enterotoxigenic E. coli for elimination and toxin neutralization.

Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of diarrheal illnesses annually ranging from mildly symptomatic cases to severe, life-threatening cholera-like diarrhea. Although ETEC are associated with long-term sequelae including malnutrition, the acute diarrheal illness is largely self-limited. Recent studies indicate that in addition to causing diarrhea, the ETEC heat-labile toxin (LT) modulates the expression of many genes in intestinal epithelia, including carcinoembryonic cell adhesion molecules (CEACAMs) which ETEC exploit as receptors, enabling toxin delivery. Here however, we demonstrate that LT also enhances the expression of CEACAMs on extracellular vesicles (EV) shed by intestinal epithelia and that CEACAM-laden EV increase in abundance during human infections, mitigate pathogen-host interactions, scavenge free ETEC toxins, and accelerate ETEC clearance from the gastrointestinal tract. Collectively, these findings indicate that CEACAMs play a multifaceted role in ETEC pathogen-host interactions, transiently favoring the pathogen, but ultimately contributing to innate responses that extinguish these common infections. Significance statementEnterotoxigenic E. coli, characterized by the production of heat-labile (LT) and heat-stable (ST) toxins, are a very common cause of diarrhea in low-income regions responsible for hundreds of millions of infections each year, and the major cause of diarrhea in travelers to endemic areas. Although these infections may be severe and cholera-like, they are typically self-limited. These studies demonstrate that extracellular vesicles produced by host intestinal cells can capture the bacteria and its secreted toxins at a distance from the cell surface, potentially acting as molecular decoys to neutralize the enterotoxins and extinguish the infection.

microbiology↗

bioRxiv2023

Calcyphosine is a microtubule-associated protein required for spindle formation and function

Calcyphosine (CAPS) is a highly conserved but little explored calcium-binding protein that shows elevated expression in many forms of human cancer. Here we uncover a role for CAPS in spindle formation during mitosis. Our experiments suggest that CAPS is a microtubule-binding, spindle-associated protein that helps create the kinetochore fibers that bind and segregate chromosomes. Knockdown of CAPS causes a variety of defects during mitosis, including uncongressed chromosomes and multi-polar spindles, as well as high levels of apoptosis and a reduced mitotic index. We find that CAPS promotes microtubule bundling, both in vitro and in cells, and knockdown of CAPS leads to reduction of thick k-fibers in the mitotic spindle. The high level of CAPS observed in many forms of cancer suggests that CAPS may promote cell proliferation, but our results indicate that CAPS overexpression has little effect on the cell cycle. This suggests that the high level of CAPS expression may be a consequence of cancer, rather than a driving force for cell proliferation.

cell biology↗