Project description:Our study looks at the dirsruption of lung circadian transcriptome that occurs when neutrophils are depleted (by application of antibodies (anti-Ly6G-1A8) to wildtype C57BL/6 mice, or Diphtheria toxin (DT) to neutrophil-specific DT-susceptible mice (MRP8-Cre;iDTR-flox)).
Project description:In this study, we used RNA sequencing to interrogate how muscle and liver autonomous clocks influence the circadian transcriptome across these two organs.
Project description:Diurnal (i.e., 24-hour) physiological rhythms depend on transcriptional programs controlled by a set of circadian clock genes/proteins. Systemic factors like humoral and neuronal signals, oscillations in body temperature, and food intake align physiological circadian rhythms with external time. Thyroid hormones (THs) are major regulators of circadian clock target processes such as energy metabolism, but little is known about how fluctuations in TH levels affect the circadian coordination of tissue physiology. In this study, a high triiodothyronine (T3) state was induced in mice by supplementing T3 in the drinking water, which affected body temperature, and oxygen consumption in a time-of-day dependent manner. 24-hour transcriptome profiling of liver tissue identified 37 robustly and time independently T3 associated transcripts as potential TH state markers in the liver. Such genes participated in xenobiotic transport, lipid and xenobiotic metabolism. We also identified 10 – 15 % of the liver transcriptome as rhythmic in control and T3 groups, but only 4 % of the liver transcriptome (1,033 genes) were rhythmic across both conditions – amongst these several core clock genes. In-depth rhythm analyses showed that most changes in transcript rhythms were related to mesor (50%), followed by amplitude (10%), and phase (10%). Gene set enrichment analysis revealed TH state dependent reorganization of metabolic processes such as lipid and glucose metabolism. At high T3 levels, we observed weakening or loss of rhythmicity for transcripts associated with glucose and fatty acid metabolism, suggesting increased hepatic energy turnover. In sum, we provide evidence that tonic changes in T3 levels restructure the diurnal liver metabolic transcriptome independent of local molecular circadian clocks.
Project description:We report the application of bulk RNA-sequencing-based technology for high-throughput profiling to examine the individual and combinatorial effects of the liver circadian clock and gut microbes on the liver transcriptome over 24-hours. Principle Component Analysis demonstrated that functionality of the liver circadian clock is the primary driver of the hepatic transcriptome profile, and presence of microbes is the secondary driver. We identified a range of significantly oscillating transcripts within each experimental group using empirical_JTK_CYCLE, and revealed an overall increase in oscillating transcripts with both the loss of cuntional liver clock and gut microbes. Network analysis via Spearman correlation revealed that a broken liver clock results in increased connections and correlated transcripts only in the presence of gut microbes. Finally, we show by differential expression and gene set enrichment analysis that several key metabolic pathways, particularly carbohydrate and lipid metabolism, were significantly downregulated when the liver clock is broken, regardless of microbial status. This study demonstrates the complex contributions of the liver circadian clock and gut microbes in transcriptome programming, both over time and overall.
Project description:Chronic liver disease and cancer are global health challenges. The role of the circadian clock (CC) as a regulator of physiology and disease is well established in animal models. However, in human liver the identity of circadian genes and their epigenetic regulation is unknown. Here, we unraveled the circadian transcriptome and epigenome of human hepatocytes using a human liver chimeric mouse model. We identified genes coding for transcription factors, chromatin modifiers, and critical enzymes which are expressed rhythmically in human hepatocytes, and which differ from the mouse liver circadian transcriptome. Moreover, we show that hepatitis C virus (HCV) infection, a major cause of liver disease and cancer world-wide, perturbs the human hepatocellular clock leading to an activation of pathways mediating steatosis, fibrosis and cancer. The HCV-disrupted rhythmic hepatic pathways remained deregulated in patients cured of HCV suggesting a major role in liver cancer development, and in the identification of therapeutic targets.
Project description:Chronic liver disease and cancer are global health challenges. The role of the circadian clock (CC) as a regulator of physiology and disease is well established in animal models. However, in human liver the identity of circadian genes and their epigenetic regulation is unknown. Here, we unraveled the circadian transcriptome and epigenome of human hepatocytes using a human liver chimeric mouse model. We identified genes coding for transcription factors, chromatin modifiers, and critical enzymes which are expressed rhythmically in human hepatocytes, and which differ from the mouse liver circadian transcriptome. Moreover, we show that hepatitis C virus (HCV) infection, a major cause of liver disease and cancer world-wide, perturbs the human hepatocellular clock leading to an activation of pathways mediating steatosis, fibrosis and cancer. The HCV-disrupted rhythmic hepatic pathways remained deregulated in patients cured of HCV suggesting a major role in liver cancer development, and in the identification of therapeutic targets.
Project description:Chronic liver disease and cancer are global health challenges. The role of the circadian clock (CC) as a regulator of physiology and disease is well established in animal models. However, in human liver the identity of circadian genes and their epigenetic regulation is unknown. Here, we unraveled the circadian transcriptome and epigenome of human hepatocytes using a human liver chimeric mouse model. We identified genes coding for transcription factors, chromatin modifiers, and critical enzymes which are expressed rhythmically in human hepatocytes, and which differ from the mouse liver circadian transcriptome. Moreover, we show that hepatitis C virus (HCV) infection, a major cause of liver disease and cancer world-wide, perturbs the human hepatocellular clock leading to an activation of pathways mediating steatosis, fibrosis and cancer. The HCV-disrupted rhythmic hepatic pathways remained deregulated in patients cured of HCV suggesting a major role in liver cancer development, and in the identification of therapeutic targets.
Project description:Purpose: To conduct a transcriptomic study of gene oscillations in mouse liver by RNA sequencing of total RNA samples from 6 different time points across the day. Specific interest is to see whether sex is a factor in large scale gene oscillations under ad-libitum control conditions and in response to caloric restriction diet, since caloric restriction was previously reported to affect gene oscillation Methods: Total RNA was isolated from 20 mg mouse liver tissue using mini spin column QIAGEN RNeasy Mini Kit (Ref #74104, Lot#163035346, Hilden, Germany) according to the manufacturer’s protocol. Sample purity was checked on Nano Drop 2000 (Thermo Fisher Scientific, Waltham, MA, USA) with 260/280 ratio ≥ 2.0 and 260/230 ratio ≥ 2.0 for every sample. Each sample used for the analysis had RNA integrity number > 7. The RNA sequencing was performed by Novogene Corporation Inc (Sacramento, CA, USA). After sample quality control, non-directional – polyA enrichment library was prepared using NEBNext Ultra™ II RNA Library Prep Kit for Illumina, and 50M reads (150bp, paired end) per sample were generated on Illumina NovaSeq 6000 platform. RNA-seq reads were mapped to the mouse protein coding genes (Ensembl: Mus_musculus; GRCm38) using Bowtie allowing up to 2-mismatches. The gene expected read counts and Transcripts Per Million (TPM) were estimated by RSEM (v1.2.3). The TPMs were further normalized by EBSeq R package to correct potential batch effect. Results: We have performed RNA sequencing analysis of mouse livers on Ad-libitum and timed Caloric Restriction diet across 6 time points in 24h. The results of subsequent compareRhythms analysis (R package) revealed that circadian rhythms in total RNA liver transcriptome are different between sexes of mice in both the number of oscillating genes and phase under ad-libitum diet. Caloric restriction increased the number of oscillating genes in both sexes and resulted in a larger overlap of rhythmic transcriptome between sexes, but did not eliminate the difference completely. The response of transcriptome to caloric restriction in terms of gain or loss of rhythm in gene expression profiles was also different between sexes. Additionally, we have shown that the lack of data stratification by sex might result in the failure to detect rhythmic changes in expression of some genes. Conclusions: Our study represents the first systematic analysis of the effect of sex on circadian rhythms of liver transcriptome under ad libitum and caloric restriction diets. We have shown that sex based differences exist in rhythmic transcriptome, as well as in the response of rhythmic transcriptome to diet. We are providing the data useful for both circadian and metabolic researchers and point out the gene candidates which may not be identified as rhythmic, if the data is not stratified by sex. With the help of GO analysis we have concluded that sex also influences the preference towards different processes to be regulated in rhythmic manner on transcriptional level - fatty acid metabolism and protein transport in males vs nucleic acid metabolism and RNA processing in females on ad-libitum diet. On calorie-restricted diet nucleic acid metabolism and RNA processing were enriched in males vs protein transport and signal transduction in females on calorie-restricted diet. These findings highlight a complex interaction of sex and diet in their effect on circadian rhythms in liver gene expression. All of the data from sequenced RNA samples from MALE liver were previously uploaded with the GSE211975 dataset. The current dataset only contains RNA-seq samples from FEMALE liver.