Biology subjects

Devlin, J. R.

Publications and source records attributed to Devlin, J. R..

4 recordsLinked to original sources

bioRxiv2026

Termination dynamics set RNAPII elongation rate and gate the response to CDK12 inactivation

The transcriptional fidelity of RNA polymerase II (RNAPII) is governed by a tight equilibrium between elongation and termination activities, a balance frequently disrupted in human diseases such as cancer. The transcriptional cyclin-dependent kinase 12 (CDK12) maintains RNAPII elongation rate and processivity throughout the gene body. Inactivation of CDK12 disrupts this homeostatic balance and causes elongation stress, slowing RNAPII and triggering premature termination at intronic polyadenylation sites (IPAs). Despite this, the precise executors of intronic premature termination under CDK12-inactivation-induced elongation stress remain poorly understood. Using genome-wide CRISPR screening combined with chemical-genetic approach, we identified a pro-termination mechanism at intronic checkpoints; upon CDK12 inactivation, SCAF4 recruits the cleavage and polyadenylation (CPA) complex through its catalytic endonuclease CPSF3 to execute premature cleavage at IPAs. Disruption of SCAF4-CPA axis prevents early termination, restores full length transcription and confers resistance to CDK12/cyclin K inhibition. Genetic loss of SCAF4 restores the RNAPII elongation rate under CDK12 inhibition, revealing that termination dynamics actively shape the rate of transcription. Supporting this model, we uncovered an anti-termination mechanism driven by KHDRBS1/SAM68, whose depletion promotes proximal termination and sensitises cells to CDK12 targeting. Our findings mechanistically couple elongation and termination activities at intronic checkpoints as joint contributors to both the processivity and elongation rate of RNAPII. This establishes termination dynamics as an active and tractable axis of the cellular response to elongation stress.

molecular biology↗

bioRxiv2022

Development of an adenosquamous carcinoma histopathology-selective lung cancer graft model

Preclinical tumor models with native tissue microenvironments provide essential tools to understand how heterogeneous tumor phenotypes relate to drug response. Here, we present syngeneic graft models of aggressive, metastasis-prone histopathology-specific NSCLC tumor types driven by KRAS mutation and loss of LKB1 (KL): adenosquamous carcinoma (ASC) and adenocarcinoma (AC). We show that subcutaneous injection of primary KL-ASC cells results in squamous cell carcinoma (SCC) tumors with high levels of stromal infiltrates, lacking the source heterogeneous histotype. Despite forming subcutaneous tumors, intravenously injected KL-AC cells were unable to form lung tumors. In contrast, intravenous injection of KL-ASC cells leads to their lung re-colonization and lesions recapitulating the mixed AC and SCC histopathology, tumor immune suppressive microenvironment and oncogenic signaling profile of source tumors, demonstrating histopathology-selective phenotypic dominance over genetic drivers. Pan-ERBB inhibition increased survival, while selective ERBB1/EGFR inhibition did not, suggesting a role of ERBB network crosstalk in resistance to ERBB1/EGFR. This immunocompetent NSCLC lung colonization model hence phenocopies key properties of the metastasis-prone ASC histopathology, and serves as a preclinical model to dissect therapy responses and metastasis-associated processes.

cancer biology↗

bioRxiv2021

Salmonella enterica serovar Typhimurium chitinases modulate the intestinal glycome and promote small intestinal invasion.

Salmonella enterica serovar Typhimurium (Salmonella) is one of the leading causes of food-borne illnesses worldwide. To colonize the gastrointestinal tract, Salmonella produces multiple virulence factors that facilitate cellular invasion. Chitinases have been recently emerging as virulence factors for various pathogenic bacterial species and the Salmonella genome contains two annotated chitinases: STM0018 (chiA) and STM0233. However, the role of these chitinases during Salmonella pathogenesis is unknown. The putative chitinase STM0233 has not been studied previously and only limited data exists on ChiA. Chitinases typically hydrolyze chitin polymers, which are absent in vertebrates. However, chiA expression was detected in infection models and purified ChiA cleaved carbohydrate subunits present on mammalian surface glycoproteins, indicating a role during pathogenesis. Here, we demonstrate that expression of chiA and STM0233 is upregulated in the mouse gut and that both chitinases facilitate epithelial cell adhesion and invasion. Salmonella lacking both chitinases showed a 70% reduction in invasion of small intestinal epithelial cells in vitro. In a gastroenteritis mouse model, chitinase-deficient Salmonella strains were also significantly attenuated in the invasion of small intestinal tissue. This reduced invasion resulted in significantly delayed Salmonella dissemination to the spleen and the liver, but chitinases were not required for systemic survival. The invasion defect of the chitinase-deficient strain was rescued by the presence of wild-type Salmonella, suggesting that chitinases are secreted. By analyzing N-linked glycans of small intestinal cells, we identified specific N-acetylglucosamine-containing glycans as potential extracellular targets of Salmonella chitinases. This analysis also revealed differential abundance of Lewis X-containing glycans that is likely a result of host cell modulation due to the detection of Salmonella chitinases. Similar glycomic changes elicited by chitinase deficient strains indicate functional redundancy of the chitinases. Overall, our results demonstrate that Salmonella chitinases contribute to intestinal adhesion and invasion through modulation of the host glycome. Author SummarySalmonella Typhimurium infection is one of the leading causes of food-borne illnesses worldwide. In order for Salmonella to effectively cause disease, it has to invade the epithelial cells lining the intestinal tract. This invasion step allows Salmonella to replicate efficiently, causing further tissue damage and inflammation. In susceptible patients, Salmonella can spread past the intestines and infect peripheral organs. It is essential to fully understand the invasion mechanism used by Salmonella to design better treatments for infection. Here, we demonstrate that the two chitinases produced by Salmonella are involved in this invasion process. We show that Salmonella chitinases interact with surface glycans of intestinal epithelial cells and promote adhesion and invasion. Using a mouse infection model, we show that Salmonella chitinases are required for the invasion of the small intestine and enhance the dissemination of Salmonella to other organs. This study reveals an additional mechanism by which Salmonella invades and causes infection.

microbiology↗

bioRxiv2019

Reprogrammed mRNA translation drives metabolic response to therapeutic targeting of ribosome biogenesis

Elevated ribosome biogenesis in oncogene-driven cancers is commonly targeted by DNA-damaging cytotoxic drugs. Our first-in-human trial of CX-5461, a novel, less genotoxic agent that specifically inhibits ribosome biogenesis via suppression of RNA Polymerase I (Pol I) transcription, revealed single agent efficacy in refractory blood cancers. Despite this clinical response, patients were not cured. In parallel, we demonstrated a marked improvement in the in vivo efficacy of CX-5461 in combination with PI3K/AKT/mTORC1 pathway inhibitors. Here we show that this improved efficacy is associated with specific suppression of translation of mRNAs encoding regulators of cellular metabolism. Importantly, acquired resistance to this co-treatment is driven by translational re-wiring that results in dysregulated cellular metabolism and induction of a cAMP-dependent pathway critical for the survival of blood cancers including lymphoma and acute myeloid leukemia. Our studies identify the molecular mechanisms underpinning the response of blood cancers to selective ribosome biogenesis inhibitors and identify metabolic vulnerabilities that will facilitate the rational design of more effective regimens for Pol I-directed therapies.

cancer biology↗