The mammalian intestine is host to a microbial community that prevents pathogen expansion through unknown mechanisms, while antibiotic treatment can increase susceptibility to enteric pathogens. Here ...we show that streptomycin treatment depleted commensal, butyrate-producing Clostridia from the mouse intestinal lumen, leading to decreased butyrate levels, increased epithelial oxygenation, and aerobic expansion of Salmonella enterica serovar Typhimurium. Epithelial hypoxia and Salmonella restriction could be restored by tributyrin treatment. Clostridia depletion and aerobic Salmonella expansion were also observed in the absence of streptomycin treatment in genetically resistant mice but proceeded with slower kinetics and required the presence of functional Salmonella type III secretion systems. The Salmonella cytochrome bd-II oxidase synergized with nitrate reductases to drive luminal expansion, and both were required for fecal-oral transmission. We conclude that Salmonella virulence factors and antibiotic treatment promote pathogen expansion through the same mechanism: depletion of butyrate-producing Clostridia to elevate epithelial oxygenation, allowing aerobic Salmonella growth.
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•Salmonella-induced colitis drives a depletion of butyrate-producing Clostridia•Antibiotic-mediated depletion of Clostridia increases colonocyte oxygenation•Increased epithelial oxygenation drives an aerobic post-antibiotic pathogen expansion•A respiration-driven Salmonella expansion in the gut is required for transmission
Paradoxically, antibiotic treatment can promote relapse of Salmonella gastroenteritis. Rivera-Chávez et al. show that antibiotic treatment lowers colonization resistance by depleting butyrate-producing Clostridia. Decreased butyrate availability increases epithelial oxygenation, thereby fueling aerobic pathogen expansion in the gut lumen. Aerobic respiration synergizes with nitrate respiration to drive fecal-oral transmission of Salmonella.
Cyclin-dependent kinase 9 (CDK9), an important regulator of transcriptional elongation, is a promising target for cancer therapy, particularly for cancers driven by transcriptional dysregulation. We ...characterized NVP-2, a selective ATP-competitive CDK9 inhibitor, and THAL-SNS-032, a selective CDK9 degrader consisting of a CDK-binding SNS-032 ligand linked to a thalidomide derivative that binds the E3 ubiquitin ligase Cereblon (CRBN). To our surprise, THAL-SNS-032 induced rapid degradation of CDK9 without affecting the levels of other SNS-032 targets. Moreover, the transcriptional changes elicited by THAL-SNS-032 were more like those caused by NVP-2 than those induced by SNS-032. Notably, compound washout did not significantly reduce levels of THAL-SNS-032-induced apoptosis, suggesting that CDK9 degradation had prolonged cytotoxic effects compared with CDK9 inhibition. Thus, our findings suggest that thalidomide conjugation represents a promising strategy for converting multi-targeted inhibitors into selective degraders and reveal that kinase degradation can induce distinct pharmacological effects compared with inhibition.
The development of effective pharmacological inhibitors of multidomain scaffold proteins, notably transcription factors, is a particularly challenging problem. In part, this is because many ...small-molecule antagonists disrupt the activity of only one domain in the target protein. We devised a chemical strategy that promotes ligand-dependent target protein degradation using as an example the transcriptional coactivator BRD4, a protein critical for cancer cell growth and survival. We appended a competitive antagonist of BET bromodomains to a phthalimide moiety to hijack the cereblon E3 ubiquitin ligase complex. The resultant compound, dBET1, induced highly selective cereblon-dependent BET protein degradation in vitro and in vivo and delayed leukemia progression in mice. A second series of probes resulted in selective degradation of the cytosolic protein FKBP12. This chemical strategy for controlling target protein stability may have implications for therapeutically targeting previously intractable proteins.
Inflammatory diseases of the gastrointestinal tract are frequently associated with dysbiosis, characterized by changes in gut microbial communities that include an expansion of facultative anaerobic ...bacteria of the Enterobacteriaceae family (phylum Proteobacteria). Here we show that a dysbiotic expansion of Enterobacteriaceae during gut inflammation could be prevented by tungstate treatment, which selectively inhibited molybdenum-cofactor-dependent microbial respiratory pathways that are operational only during episodes of inflammation. By contrast, we found that tungstate treatment caused minimal changes in the microbiota composition under homeostatic conditions. Notably, tungstate-mediated microbiota editing reduced the severity of intestinal inflammation in mouse models of colitis. We conclude that precision editing of the microbiota composition by tungstate treatment ameliorates the adverse effects of dysbiosis in the inflamed gut.
Conflicting results on prognostic factors for advanced epithelial ovarian cancer (EOC) have been reported because of small sample size and heterogeneity of study population. The purpose of this study ...was to identify factors predictive of poor prognosis in a similarly treated population of women with advanced EOC.
A retrospective review of demographic, pathologic, treatment, and outcome data from 1,895 patients with International Federation of Gynecology and Obstetrics stage III EOC who had undergone primary surgery followed by six cycles of intravenous platinum/paclitaxel was conducted. A proportional hazards model was used to assess the association of prognostic factors with progression-free survival (PFS) and overall survival (OS).
Increasing age was associated with increased risks for disease progression (HR = 1.06; 95% CI, 1.02 to 1.11 for an increase every 10 years) and death (HR = 1.12; 95% CI, 1.06 to 1.18). Mucinous or clear-cell histology was associated with a worse PFS and OS compared with serous carcinomas. Patients with performance status (PS) 1 or 2 were at an increased risk for recurrence compared with PS 0 (HR = 1.12; 95% CI, 1.01 to 1.24). Compared with patients with microscopic residual disease, patients with 0.1 to 1.0 cm and > 1.0 cm residual disease had an increased risk of recurrence (HR = 1.96; 95% CI, 1.70 to 2.26; and HR = 2.36; 95% CI, 2.04 to 2.73, respectively) and death (HR = 2.11; 95% CI, 1.78 to 2.49; P < .001; and HR = 2.47; 95% CI, 2.09 to 2.92, respectively).
Age, PS, tumor histology, and residual tumor volume were independent predictors of prognosis in patients with stage III EOC. These data can be used to identify patients with poor prognosis and to design future tailored randomized clinical trials.
Intestinal inflammation is frequently associated with an alteration of the gut microbiota, termed dysbiosis, which is characterized by a reduced abundance of obligate anaerobic bacteria and an ...expansion of facultative Proteobacteria such as commensal E. coli. The mechanisms enabling the outgrowth of Proteobacteria during inflammation are incompletely understood. Metagenomic sequencing revealed bacterial formate oxidation and aerobic respiration to be overrepresented metabolic pathways in a chemically induced murine model of colitis. Dysbiosis was accompanied by increased formate levels in the gut lumen. Formate was of microbial origin since no formate was detected in germ-free mice. Complementary studies using commensal E. coli strains as model organisms indicated that formate dehydrogenase and terminal oxidase genes provided a fitness advantage in murine models of colitis. In vivo, formate served as electron donor in conjunction with oxygen as the terminal electron acceptor. This work identifies bacterial formate oxidation and oxygen respiration as metabolic signatures for inflammation-associated dysbiosis.
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•Genes encoding respiratory pathways are overrepresented in the dysbiotic microbiome•Utilization of microbiota-derived formate enhances E. coli fitness in the inflamed gut•Formate concentrations in the gut are elevated during inflammation-associated dysbiosis•During gut inflammation, formate utilization by E. coli requires oxygen respiration
Intestinal inflammation is associated with changes in the microbiota composition (dysbiosis), such as the expansion of the commensal Enterobacteriaceae population. Hughes and Winter et al. show that utilization of microbiota-derived formate as electron donor and oxygen as terminal electron acceptor contribute to the bloom of Enterobacteriaceae in the inflamed gut.
Intestinal Paneth cells limit bacterial invasion by secreting antimicrobial proteins, including lysozyme. However, invasive pathogens can disrupt the Golgi apparatus, interfering with secretion and ...compromising intestinal antimicrobial defense. Here we show that during bacterial infection, lysozyme is rerouted via secretory autophagy, an autophagy-based alternative secretion pathway. Secretory autophagy was triggered in Paneth cells by bacteria-induced endoplasmic reticulum (ER) stress, required extrinsic signals from innate lymphoid cells, and limited bacterial dissemination. Secretory autophagy was disrupted in Paneth cells of mice harboring a mutation in autophagy gene Atg16L1 that confers increased risk for Crohn’s disease in humans. Our findings identify a role for secretory autophagy in intestinal defense and suggest why Crohn’s disease is associated with genetic mutations that affect both the ER stress response and autophagy.
Chronic inflammation and gut microbiota dysbiosis, in particular the bloom of genotoxin-producing
strains, are risk factors for the development of colorectal cancer. Here, we sought to determine ...whether precision editing of gut microbiota metabolism and composition could decrease the risk for tumor development in mouse models of colitis-associated colorectal cancer (CAC). Expansion of experimentally introduced
strains in the azoxymethane/dextran sulfate sodium colitis model was driven by molybdoenzyme-dependent metabolic pathways. Oral administration of sodium tungstate inhibited
molybdoenzymes and selectively decreased gut colonization with genotoxin-producing
and other Enterobacteriaceae. Restricting the bloom of Enterobacteriaceae decreased intestinal inflammation and reduced the incidence of colonic tumors in two models of CAC, the azoxymethane/dextran sulfate sodium colitis model and azoxymethane-treated,
-deficient mice. We conclude that metabolic targeting of protumoral Enterobacteriaceae during chronic inflammation is a suitable strategy to prevent the development of malignancies arising from gut microbiota dysbiosis.
Processive elongation of RNA Polymerase II from a proximal promoter paused state is a rate-limiting event in human gene control. A small number of regulatory factors influence transcription ...elongation on a global scale. Prior research using small-molecule BET bromodomain inhibitors, such as JQ1, linked BRD4 to context-specific elongation at a limited number of genes associated with massive enhancer regions. Here, the mechanistic characterization of an optimized chemical degrader of BET bromodomain proteins, dBET6, led to the unexpected identification of BET proteins as master regulators of global transcription elongation. In contrast to the selective effect of bromodomain inhibition on transcription, BET degradation prompts a collapse of global elongation that phenocopies CDK9 inhibition. Notably, BRD4 loss does not directly affect CDK9 localization. These studies, performed in translational models of T cell leukemia, establish a mechanism-based rationale for the development of BET bromodomain degradation as cancer therapy.
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•Competitive BET bromodomain inhibition differs from BET protein degradation•BET proteins are master regulators of productive transcription elongation•BET protein degradation is inconsequential for CDK9 recruitment•BET degradation provokes an assembly defect of a transcription elongation complex
Winter et al. delineate fundamental differences in the molecular pharmacology of BET bromodomain inhibition and BET protein degradation. Comparative studies led to the identification of BET proteins as master regulators of transcription elongation. Acute BET protein degradation prompts a global collapse of productive elongation that is independent of CDK9 recruitment.
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