Microarray of hippocampus from 5mo wt, Bmal1 KO and Nr1d1 (Rev-Erb-alpha) KO mice at a single timepoint
ABSTRACT: Deletion of the circadian clock proteins Bmal1 or Nr1d1 (also known as Rev-Erb-alpha) can not only cause circadian dysfunction, but also neuroinflammation in the hippocampus. In this array, 3 wt, 2 Bmal1 KO, and 2 Nr1d1 KO mice, all 5mo, were kept in standard 12h:12h light:dark condition, then anesthetized and perfused with PBS+heparin. Mice were harvest in between noon and 3pm. Whole hippocampus was removed and flash frozen, then RNA was extracted using Trizol reagent and PureLink RNA columns, per manufacturers instructions. RNA microarray analysis was performed by the Washington Univ. Genome Technology Access Center using Agilent Mouse 4x44K mouse V2 array.
Project description:The aim of this study was to examine the effect of genetic disruption of the circadian clock on gene expression in the cortex across timepoints. Circadian clock protein regulate many critical aspects of cellular function, and Bmal1 knockout mice develop severe neuroinflammation, suggesting a role for circadian clock gene in brain homeostatic function. We compared brain-specific Bmal1 KO mice (Nestin-Cre;Bmal1(flox/flox) with Per1/2 double mutant mice, in order to assess the effects of deletion of the positive and negative limbs of the core clock. 11mo Cre-, NestinCre+/-;Bmal1(fx/fx), or Per1brdm,Per2brdm mice were entrained to 12h light:dark conditions with lights on at 6am for one month, then placed in constant darkness for 24 hours, after which mice were harvested at 6am (CT6) or 6pm (CT18), still in the dark. Mice were anesthetized in the dark, then perfused briefly with PBS+heparin. The brain was then quickly dissected on a cold surface, and the cerebral cortex flash frozen in liquid nitrogen. Cortex samples were mechanically dissociated with a Qiashredder device, then extracted with chloroform and diluted in 70% ethanol. RNA was extracted using Qiagen RNEasy kit according to manufacturers specifications. cDNAs were chemically labeled with Kreatech ULS RNA labeling kit (Kreatech Diagnostics) and Cy5-labeled cDNAs were hybridized to Agilent Mouse v2 4x44K microarrays (G4846A-026655).
Project description:To explore the circadian regulations of Bmal1, we examined the transcriptome changes in mouse livers upon Bmal1 knock out at two circadian time points, CT0 and CT12. To explore the circadian regulations of Nr1d1, we examined the transcriptome changes in mouse livers upon Nr1d1 knock out at two circadian time points, CT0 and CT12. To explore interactome of lnc-Crot, 4C-seq was performed with lnc-Crot as bait region at CT6 and CT18. Overall design: RNA-seq of WT and KO at CT0 and CT12. 4C-seq at CT6 and CT18.
Project description:We found that a H3K4 specific histone methyltransferase MLL1, a mammalian homologue of Drosophila trithorax, is essential for circadian transcription. MLL1 is in a complex with CLOCK:BMAL1 and contributes to their rhythmic recruitment to circadian promoters and cyclic H3K4 tri-metylation. To analyze the function of MLL1 on circadian gene regulation, we performed comparative microarray analysis of global gene expression levels in WT and MLL1-deficient MEF, at two different circadian time points (CT18 and CT30). This analysis identified several genes whose expression levels were remarkably changed between CT18 and CT30 in WT and MLL1-KO MEF. Typical clock-regulated genes such as Per2, Per3, Bmal1, or Dbp were found to be changing in WT but not in MLL1-KO MEFs. Overall design: Wild-type and MLL1-KO MEF at two circadian time point (CT18 and 30), three replicates for each hour.
Project description:Gene expression in the liver has been studied extensively in normal mice, but not in mice with circadian disruption. We use a tamoxifen-inducible Lox/Cre KO mouse strain with the most important clock gene knocked out, BMAL-1. The aim of this experiment was to study the effect of circadian disruption on gene expression in the liver by comparing conditional Bmal1 KO mice with WT mice using RNA-seq. All mice were housed under 12h:12h LD conditions with free access to food and water. Seven days after the last dose of tamoxifen, mice were kept under constant darkness for 36 h and then sacrificed. Four mice per genotype were sacrificed in darkness every 4h for 20h (6 time points). Illumina TruSeq RNA Sample Prep v2 was used for library construction and samples were sequenced on an Illumina HiSeq 2000. RNA-seq data were aligned by STAR, and data were normalized with a resampling strategy (https://github.com/itmat/Normalization). Overall design: Time-series liver mRNA profiles of 4- to 6-month-old male wild type (WT) and Bmal1 knockout (KO) mice were generated by sequencing, four mice per genotype per timepoint, using Illumina HiSeq 2000.
Project description:We use a conventional (pre-natal) Bmal1 KO (cKO) mouse strain to investigate the effect of circadian disruption on gene expression in the liver by comparing cKO mice with wild type (WT) mice using RNA-Seq. All mice were housed under 12h:12h LD conditions with free access to food and water. Three mice per genotype were sacrificed every 4 h for 20 h (6 time points). Illumina TruSeq Stranded mRNA Sample Prep Kit Set A was used for library construction and samples were sequenced on an Illumina HiSeq 2500. RNA-seq data were aligned by STAR, and data were normalized with a resampling strategy (https://github.com/itmat/Normalization). Overall design: Time-series liver mRNA profiles of 6.4- to 13.9-week-old male and female wild type (WT) and Bmal1 knockout (KO) mice were generated by sequencing, three mice per genotype per timepoint, using Illumina HiSeq 2500.
Project description:The mammalian circadian clock is a molecular oscillator composed of a feedback loop that involves transcriptional activators CLOCK and BMAL1, and repressors Cryptochrome (CRY) and Period (PER). Here we show that a direct CLOCK-BMAL1 target gene, Gm129, is a novel regulator of the feedback loop. ChIP analysis revealed that the CLOCK:BMAL1:CRY1 complex strongly occupies the promoter region of Gm129. Both mRNA and protein levels of GM129 exhibit high amplitude circadian oscillations in mouse liver, and Gm129 gene encodes a nuclear-localized protein that directly interacts with BMAL1 and represses CLOCK:BMAL1 activity. In vitro and in vivo protein-DNA interaction results demonstrate that, like CRY1, GM129 functions as a repressor by binding to the CLOCK:BMAL1 complex on DNA. Although Gm129-/- or Cry1-/- Gm129-/- mice retain a robust circadian rhythm, the peaks of Nr1d1 and Dbp mRNAs in liver exhibit significant phase delay compared to control. Our results suggest that, in addition to CRYs and PERs, GM129 protein contributes to the transcriptional feedback loop by modulating CLOCK:BMAL1 activity as a transcriptional repressor. Examination of 3 transcriptional regulators in mouse liver
Project description:To investigate the role of the circadian clock gene Bmal1 in skeletal muscle, we compared the circadian transcriptomes of fast tibialis anterior (TA) and slow soleus (SOL) skeletal muscles from muscle-specific Bmal1 KO (mKO) and their control Cre- littermates (Ctrl). Keyword: Circadian Transcriptome, time course 72 samples were analyzed, comprised of 4 experimental groups (Ctrl SOL, mKO SOL, Ctrl TA, mKO TA), with 3 biological replicates for each time point sampled every 4 hours for 24 hours. SOL and TA muscles were collected from the same animals, as indicated by Source Animal ID data column
Project description:While several physiological skin parameters vary in a circadian manner, the identity of genes participating in chronobiology of skin remains unknown, leading us to define the circadian transcriptome of mouse skin at two different stages of the hair cycle, telogen and anagen. The circadian transcriptomes of telogen and anagen skin are largely distinct, with the former dominated by genes involved in cell proliferation and metabolism. The expression of many metabolic genes is antiphasic to cell cycle related genes, the former peaking during the day and the latter peaking at the night. Consistently, accumulation of reactive oxygen species, a byproduct of oxidative phosphorylation, and S-phase are antiphasic to each other in telogen skin. Furthermore, the circadian variation in S-phase is controlled by BMAL1 intrinsic to keratinocytes as keratinocyte-specific deletion of Bmal1 obliterates time of day dependent synchronicity of cell division in the epidermis leading to a constitutively elevated cell proliferation. Consistent with higher cellular susceptibility to UV-induced DNA damage during S phase, we found that mice are most sensitive to UVB-induced DNA damage in the epidermis at night. As maximum numbers of keratinocytes go through S phase in the late afternoon in the human epidermis, we speculate that in humans the circadian clock imposes regulation of epidermal cell proliferation such that skin is at a particularly vulnerable stage during times of maximum UV exposure, thus contributing to the high incidence of human skin cancers. Whole skin was collected at ZT22. Where ZT number indicates the number of hours elapsed from when lights are switched on. ZT0 = lights on (6am). ZT12=lights off (6pm). Het mice designate a presence of one Bmal1 mutant allele and one wt allele. KO mice designate mice germline deleted for both copies of Bmal1 allele. Total RNA was purified from the skin of each biological littermate replicate.
Project description:To explore the circadian regulations of Bmal1, we examined the transcriptome changes in mouse livers upon Bmal1 knock out at two circadian time points, CT0 and CT12. Overall design: RNA-seq of WT and KO at CT0 and CT12.
Project description:Mammalian circadian rhythm is established by the negative feedback loops consisting of a set of clock genes, which lead to the circadian expression of thousands of downstream genes. As genome-wide transcription is organized under the high-order chromosome structure, it is unclear how circadian gene expression is influenced by chromosome structure. In this study, we focus on the function of chromatin structure proteins cohesin as well as CTCF (CCCTC-binding factor) in circadian rhythm. We analyzed the interactome of a Bmal1-bound enhancer upstream of a clock gene, Nr1d1, by 4C-seq and observed that cohesin binding sites are enriched in the interactome. Integrating circadian transcriptome data and cistrome data, we found that cohesin-CTCF co-binding sites tend to insulate the phases of circadian oscillating genes while cohesin-non-CTCF sites facilitate the interaction between circadian enhancer and promoter. A coarse-grained model integrating the long-range effect of cohesin and CTCF markedly improved our mechanistic understanding of circadian gene expression. This model is subsequently supported by our RNA-seq data from cohesin knockout cells. Cohesin is required at least in part for driving the circadian gene expression by facilitating the enhancer-promoter looping. Taken together, our study provided a novel insight into the relationship between circadian transcriptome and the high-order chromosome structure. 4C-seq of a Bmal1 enhancer in mouse liver