Circadian Liver Gene Expression in Animals on Normal Chow or High Fat Diet
Ontology highlight
ABSTRACT: Circadian and metabolic processes are codependent. This experiment was designed to understand how a high fat diet affects circadian gene expression in the liver. Circadian gene expression in the liver is necessary for energy balance. Animals consuming normal chow or high fat diet (60% kcal from fat) for ten weeks were analyzed for circadian gene expression. Livers were harvested from animals every four hours throughout the circadian cycle.
Project description:Hair follicles undergo recurrent cycling of controlled growth (anagen), regression (catagen), and relative quiescence (telogen) with a defined periodicity. Taking a genomics approach to study gene expression during synchronized mouse hair follicle cycling, we discovered that, in addition to circadian fluctuation, CLOCK-regulated genes are also modulated in phase with the hair growth cycle. During telogen and early anagen, circadian clock genes are prominently expressed in the secondary hair germ, which contains precursor cells for the growing follicle. Analysis of Clock and Bmal1 mutant mice reveals a delay in anagen progression, and the secondary hair germ cells show decreased levels of phosphorylated Rb and lack mitotic cells, suggesting that circadian clock genes regulate anagen progression via their effect on the cell cycle. Consistent with a block at the G1 phase of the cell cycle, we show a significant upregulation of p21 in Bmal1 mutant skin. While circadian clock mechanisms have been implicated in a variety of diurnal biological processes, our findings indicate that circadian clock genes may be utilized to modulate the progression of non-diurnal cyclic processes. To gain molecular understanding of the the hair cycle delay in Bmal mutant mice, we profiled the dorsal skin of Bmal knockout (-/-) and their heterozygous (+/-) littermates at P22. At P22, the skin samples are comparable because all the samples are in telogen just prior to the hair cycle delay was observed. Histological sections were used to classify each sample into specific stage of the hair growth cycle based on established morphological guidelines. RNA from each mouse dorsal skin were separately hybridized to an Affymetrix Mouse Gene 1.0 ST array.
Project description:Expression profiles in WT MEF at different circadian time point after dexamethasone synchronization. We used the Affymetrix expression microarrays to detail the circadian gene expression from wild type mouse embryonic fibroblasts during a 24 hour circadian cycle. For each circadian time point (CT), three biological replicates were analyzed.
Project description:This SuperSeries is composed of the following subset Series: GSE38622: Bmal1 controls circadian cell proliferation and susceptibility to UVB-induced DNA damage in the epidermis [telogen]. GSE38623: Bmal1 controls circadian cell proliferation and susceptibility to UVB-induced DNA damage in the epidermis [Anagen] GSE38624: Bmal1 controls circadian cell proliferation and susceptibility to UVB-induced DNA damage in the epidermis [Bmal1 KO] Refer to individual Series
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 4 hour intervals for 48 hours. Where ZT number indicates the number of hours elapsed from when lights are switched on. ZT0 = lights on (6am). ZT12=lights off (6pm). Total RNA was purified from the skin of each mouse and equal amount of RNA from the 3 replicates for each time point were pooled. Telogen samples were collected from skin of P46 male mice.
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: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 4 hour intervals for 48 hours. ZT number indicates the number of hours elapsed from when lights are switched on. ZT0 = lights on (6am). ZT12=lights off (6pm). Total RNA was purified from the skin of each mouse and equal amount of RNA from the 3 replicates for each time point were pooled. Anagen samples were collected from skin of P30 male mice.
Project description:We found that the circadian protein PER2 interacts with the nuclear receptor PPARgamma to repress its activity. PPARgamma is a master regulator of adipogenesis and lipid metabolism and is very abundant in adipose tissue. We used microarrays to detail the global program of gene expression in adipose tissue lacking the per2 gene. This analysis identified several PPARgamma target genes up-regulated in adipose tissue from per2-/- mice. Per2-/- and per2+/+ male mice (Bae et al., 2001) were housed under 12 hr light/12 hr dark (LD) cycles. Mice 20 weeks old were sacrificed at the same time and adipose tissue (WAT and BAT) was collected for RNA extraction. 3 biological replicates per mouse/tissue.
Project description:To determine gene expression changes induced by ATF4 overexpression, RNA was isolated from BEAS2B cells after overexpression of ATF4 or negative control. mRNA expression was profiled using Affymetrix Human Gene 1.0 ST Arrays. RNA isolated from BEAS2B cells after overexpression of ATF4 or empty vector was processed and hybridized to Affymetrix Human Gene 1.0 ST Arrays. Experiments were performed in triplicate. Data from the 6 microarrays were used for RMA normalization. RMA normalization was performed in the R statsitical environment using the affy package. A t-test was used to determine the association of gene expression with ATF4 overexpression.
Project description:Multiple genes are dysregulated in hindlimb buds of Nipbl-deficient embryos. In all, more than 1000 limb bud genes were found to be significantly altered in expression by microarray analysis of E10.5 mouse hindlimb buds. Small changes in expression (mostly decreases) were observed for genes involved in FGF, BMP, and SHH pathways, as well as numerous genes involved in the Wnt/planar cell polarity signaling pathway. Genes involved in the Mediator complex, Cohesin function, and Hox gene expression and functions were also dysregulated in Nipbl deficient limb buds. Microarray analysis using RNA extracted from E10.5 hindlimb limb buds harvested from stage-matched Nipbl+/- (n=12) and wildtype (n=12)
Project description:Comparison of the hepatic circadian transcriptomes reveals that SIRT6 and SIRT1 separately control transcriptional specificity, and therefore, define distinctly partitioned classes of circadian genes. Livers from WT and SIRT6 KO mice, and livers from WT and SIRT1 KO mice, were harvested over the circadian cycle at ZT 0, 4, 8, 12, 16 and 20 for gene expression analysis.