Biology subjects

Sewell, J.

Publications and source records attributed to Sewell, J..

4 recordsLinked to original sources

bioRxiv2025

PKN2 regulates cell-junctions to limit colitis and colon tumour formation

Intestinal barrier failure is a defining feature of inflammatory bowel disease and a key driver of inflammation-associated colorectal cancer. However, the epithelial mechanisms that preserve barrier stability during inflammatory stress remain incompletely defined. Here, we identify the Rho-regulated kinase PKN2 as a non-redundant safeguard of tight junction integrity and a candidate tumour suppressor in colitis-associated colorectal cancer. Conditional PKN2 deletion in mice sensitised the colon to inflammatory injury and significantly increased adenoma formation in an inflammatory cancer model, with tumour burden tightly correlating with colitis severity. Mechanistically, PKN2 localises to tight junctions and is required to stabilise barrier integrity during injury in mouse and organoid models. PKN2 loss induces transcriptional programs conserved in human inflammatory bowel disease, where reduced PKN2 expression associates with increased disease severity and altered therapeutic response. Notably, PKN2 is encoded within genomic loci previously linked to intestinal inflammation susceptibility and tumour suppression in both humans and mice. Our findings identify PKN2 as a functional effector underlying these phenotypes and demonstrate that even heterozygous loss is sufficient to confer heightened sensitivity to inflammatory injury and tumour initiation, positioning PKN2 as a central regulator of tight junction stability that shapes disease severity, treatment response and cancer risk.

cell biology↗

bioRxiv2025

The penetrant chordoid glioma PRKCA mutation is an oncogenic gain-of-function kinase inactivation eliciting early onset chondrosarcoma in mice.

The penetrant PRKCA D463H mutation, a biomarker and potential driver in chordoid glioma, was found to provoke the development of chondrosarcomas in heterozygous knock-in mice. This mutation entirely abrogates kinase activity, but strikingly no oncogenic phenotype is observed for the related inactivating mutation D463N indicating that the lack of activity is not the driver. In cells, the D463H mutant closely mirrored PKC WT behaviours and retained ATP binding, contrary to the related D463N mutant. Mechanistically, the PKC D463H mutant protein was found to display quantitative alterations to the PKC interactome, enhancing association with epigenetic regulators. This aligned with transcriptomic changes which resembled an augmented PKC expression program, with enhanced BRD4, Myc and TGF{beta} signatures. D463H dependent reduced sensitivity to the BET inhibitors JQ1 and AZD5153 indicates the functional importance of these pathways. The data show that D463H is a dominant gain-of-function oncogenic mutant, operating through a non-catalytic allosteric mechanism. One Sentence SummaryA PKC catalytic inactivating mutation confers gain-of-function properties - a paradigm shift in kinase actions.

cancer biology↗

bioRxiv2025

TNF signaling maintains local restriction of bacterial founder populations in intestinal and systemic sites during oral Yersinia infection

Enteroinvasive bacterial pathogens are responsible for an enormous worldwide disease burden that critically affects the young and immunocompromised. Yersinia pseudotuberculosis is a Gram-negative enteric pathogen, closely related to the plague agent Y. pestis, that colonizes intestinal tissues, induces the formation of pyogranulomas along the intestinal tract, and disseminates to systemic organs following oral infection of experimental rodents. Prior studies proposed that systemic tissues were colonized by a pool of intestinal replicating bacteria distinct from populations within Peyers patches and mesenteric lymph nodes. Whether bacteria within intestinal pyogranulomas serve as the source for systemic dissemination, and the relationship between bacterial populations within different tissue sites is poorly defined. Moreover, the factors that regulate Yersinia colonization and dissemination are not well understood. Here, we demonstrate, using Sequence Tag-based Analysis of Microbial Populations in R (STAMPR), that remarkably small founder populations independently colonize intestinal and systemic tissues. Notably, intestinal pyogranulomas contain clonal populations of bacteria that are restricted and do not spread to other tissues. However, populations of Yersinia are shared among systemic organs and the blood, suggesting that systemic dissemination occurs via hematogenous spread. Finally, we demonstrate that TNF signaling is a key contributor to the bottlenecks limiting both tissue colonization and lymphatic dissemination of intestinal bacterial populations. Altogether, this study reveals previously undescribed aspects of infection dynamics of enteric bacterial pathogens. ImportanceBacterial escape from the intestine can lead to severe disease, including sepsis, organ damage, and death. However, the intestinal bacterial population dynamics governing the colonization of mucosal and systemic tissues and the intestinal sites that seed systemic spread are not clear. Yersinia pseudotuberculosis is a rodent and human intestinal pathogen closely related to the plague agent and provides a natural rodent-adapted model to study systemic bacterial dissemination. Our findings define the infection dynamics of enteric Yersinia and the impact of the innate immune system on Yersinia colonization of the intestine and systemic organs.

microbiology↗

bioRxiv2020

Comprehensive mapping of the human cytokine gene regulatory network

Proper cytokine gene expression is essential in development, homeostasis, and immune responses. Studies on the transcriptional control of cytokine genes have mostly focused on highly researched transcription factors (TFs) and cytokines, resulting in an incomplete portrait of cytokine gene regulation. Here, we use enhanced yeast one-hybrid (eY1H) assays to derive a comprehensive network comprising 1,380 interactions between 265 TFs and 108 cytokine gene promoters, greatly expanding the known repertoire of TF-cytokine gene interactions. We found an enrichment of nuclear receptors and confirmed their role in cytokine regulation in primary macrophages. Additionally, we used the eY1H-derived network as a framework to identify pairs of TFs that synergistically modulate cytokine gene expression, and to identify novel TF-cytokine regulatory axes in immune diseases and immune cell lineage development. Overall, the eY1H data provides a rich resource to study cytokine regulation in a variety of physiological and disease contexts.

immunology↗