Project description:The circadian clock orchestrates rhythms in physiology and behavior, allowing the organism to adapt to daily environmental changes. Recently, efforts have been made to unravel the connection between the circadian clock and metabolism and to understand how the peripheral clock in different organs coordinates circadian responses to maintain metabolic homeostasis. It is becoming clear that diet can influence diurnal rhythms, however, the molecular mechanisms responsible for alterations in daily oscillations and how tissue-specific clocks interpret a nutritional challenge are not well understood. Here, we reveal tissue-specific circadian plasticity in response to a ketogenic diet (KD) in both the liver and intestine and a remarkable deviation within these two tissues following subsequent carbohydrate supplementation. KD caused a dramatic change in the circadian transcriptome in both liver and intestine in a tissue-specific fashion. In particular, both the amplitude of clock genes as well as specific BMAL1 recruitment was profoundly altered by KD while the intestinal clock was devoid of such plasticity. While PPARG nuclear accumulation was circadian in both tissues, it showed substantial phase specificity as did downstream targets. Finally, the gut and liver clocks had distinct responses to carbohydrate supplementation to KD composition, suggesting a higher plasticity in the ileum whose gene expression was almost restored to control baseline. For the first time our results demonstrate how nutrients modulate clock function in a tissue-specific manner, suggesting that a food stress arouses unique circadian molecular signatures in distinct peripheral tissues.
Project description:Circadian rhythms regulate diverse aspects of gastrointestinal physiology ranging from the composition of microbiota to motility. However, development of the intestinal circadian clock and detailed molecular mechanisms regulating circadian physiology of the intestine remain largely unknown. The lack of appropriate human model systems that enable organ- and/or diseasespecific interrogation of clock functions is a major obstacle hindering advancements of translational applications using chronotherapy. In this report, we show that both pluripotent stem cell-derived human intestinal organoids engrafted into mice and patient-derived human intestinal enteroids (HIEs) possess robust circadian rhythms, and demonstrate circadian phase-dependent necrotic cell death responses to Clostridium difficile toxin B (TcdB). Intriguingly, mouse and human enteroids demonstrate anti-phasic necrotic cell death responses. RNA-Seq data show ~4% of genes are rhythmically expressed in HIEs. Remarkably, we observe anti-phasic gene expression of Rac1, a small GTPase directly inactivated by TcdB, between mouse and human enteroids. Importantly, the observed circadian time-dependent necrotic cell death response is abolished in both mouse enteroids and human intestinal organoids (HIOs) lacking robust circadian rhythms. Our findings uncover robust functions of circadian rhythms regulating critical clock-controlled genes (CCGs) in human enteroids governing organism-specific, circadian phasedependent necrotic cell death responses. Our data highlight unique differences between mouse and human enteroids, and lay a foundation for human organ- and disease-specific investigation of clock functions using human organoids for translational applications.
Project description:Host-microbiome-dietary interactions play crucial roles in regulating human health, yet direct functional assessment of their interplays, cross-regulations and downstream disease impacts remains challenging. We adopted metagenome-informed metaproteomics (MIM), in both mice and humans, to simultaneously explore host, dietary, and species-level microbiome interactions across diverse scenarios, including commensal and pathogen colonization, nutritional modifications, and antibiotic-induced perturbations. Implementation of MIM in murine auto-inflammation and in human IBD characterized a ‘compositional dysbiosis’ and a concomitant, species-specific ‘functional dysbiosis’ driven by suppressed commensal responses to inflammatory host signals. Microbiome transfers unraveled early-onset kinetics of these host-commensal cross-responsive patterns, while predictive analyses identified candidate fecal host-microbiome IBD biomarker protein pairs outperforming S100A8/S100A9 (calprotectin). Importantly, a simultaneous fecal nutrient assessment enabled determination of IBD-related consumption patterns, dietary treatment compliance and small-intestinal digestive aberrations. Collectively, a parallelized dietary-bacterial-host MIM assessment functionally uncovers trans-kingdom interactomes shaping gastrointestinal ecology, while offering personalized diagnostic and therapeutic insights into microbiome-associated disease.
Project description:The circadian clock has been shown to regulate inflammatory bowel disease (IBD), but the underlying mechanisms remain unclear. Here, we observed that the mice in the active phase of the circadian clock were more tolerant to dextrose sodium sulfate (DSS)-induced colitis, compared to those in the resting phase. Furthermore, we found that the circadian gene Bmal1 displayed a dynamic expression pattern in mouse colonic epithelium during the circadian clock, with a high level in the resting phase and a low in the active phase. Ablation of Bmal1 in the intestinal epithelium reduced inflammatory symptoms in the colon of the DSS-treated mice. The mice with Bmal1 deletion exhibited no obvious disruption on intestinal homeostasis, rather were more resistant to DSS-induced inflammation, with less body weight change, fewer pathological symptoms, and greater epithelial integrity, compared to the control group. Mechanistically, BMAL1 promoted apoptosis by binding to the apoptosis-related genes, such as Bax, P53 and Bak1, and transcriptionally activating their expression. Collectively, our results reveal the Bmal1-centered circadian clock is involved in intestinal repair upon injure. Clinically, targeting Bmal1 function may be a promising approach to treat inflammation-related gastrointestinal tract diseases.