Project description:One hundred ninety wildtype male C57BL/6J mice age 7-10 weeks were purchased from Jackson Laboratory and entrained to a 12:12 light:dark cycle for 2 weeks. Mice were placed in light-tight boxes on a 12:12 LD cycle for 4 weeks, then released into constant darkness. Starting 30 hours after entry into DD (CT18), tissues from 5 (skeletal muscle) or 10 (liver or SCN) wildtype mice were collected every 4 hours for 48 hours, for a total of 12 timepoints. At timepoints 34 through 58 hours in DD, tissues from age-matched male C57BL/6J Clock/Clock homozygous mutant mice that had been treated with the same light entrainment protocol as the wildtype were collected. Tissues were collected from 5 Clock/Clock mutants at each timepoint except for 34 and 46 hours after the onset of DD, when tissues from 10 Clock/Clock mice were collected and run as independent replicates. Mice were sacrificed by cervical dislocation, and the optic nerves were severed in complete darkness; brain dissection was performed using illumination from an infrared viewer (FJW Industries, Palatine, IL). SCNs were dissected out, pooled at a density of 5 per tube in 100 ul RNAlater (Ambion, Austin, TX), frozen on dry ice, and stored at â80 degrees C until use. Keywords: SuperSeries This reference Series links data in the following related Series: GSE3746 Circadian skeletal muscle_wt and Clock mutants GSE3748 Circadian liver_wt and Clock mutants
Project description:Molecular analysis of circadian rhythm in mice. Liver tissue of wildtype, Clock mutant and Cry deficient C57BL/6 8- to 10-week-old male mice examined. Keywords = circadian rhythm Keywords: other
Project description:One hundred ninety wildtype male C57BL/6J mice age 7-10 weeks were purchased from Jackson Laboratory and entrained to a 12:12 light:dark cycle for 2 weeks. Mice were placed in light-tight boxes on a 12:12 LD cycle for 4 weeks, then released into constant darkness. Starting 30 hours after entry into DD (CT18), tissues from 5 (skeletal muscle) or 10 (liver or SCN) wildtype mice were collected every 4 hours for 48 hours, for a total of 12 timepoints. At timepoints 34 through 58 hours in DD, tissues from age-matched male C57BL/6J Clock/Clock homozygous mutant mice that had been treated with the same light entrainment protocol as the wildtype were collected. Tissues were collected from 5 Clock/Clock mutants at each timepoint except for 34 and 46 hours after the onset of DD, when tissues from 10 Clock/Clock mice were collected and run as independent replicates. Mice were sacrificed by cervical dislocation, and the optic nerves were severed in complete darkness; brain dissection was performed using illumination from an infrared viewer (FJW Industries, Palatine, IL). SCNs were dissected out, pooled at a density of 5 per tube in 100 ul RNAlater (Ambion, Austin, TX), frozen on dry ice, and stored at –80 degrees C until use. This SuperSeries is composed of the SubSeries listed below.
Project description:The circadian clock is comprised of proteins that form negative feedback loops, which regulate the timing of global gene expression in a coordinated 24 hour cycle. As a result, the plant circadian clock is responsible for regulating numerous physiological processes central to growth and survival. To date, most plant circadian clock studies have relied on diurnal transcriptome changes to elucidate molecular connections between the circadian clock and observable phenotypes in wild-type plants. Here, we have combined high-throughput RNA-sequencing and mass spectrometry to comparatively characterize the lhycca1, prr7prr9, gi and toc1 circadian clock mutant rosette transcriptome and proteome at the end-of-day and end-of-night.
Project description:Circadian rhythms are a series of endogenous autonomous 24-hour oscillations generated by the circadian clock. At the molecular level, the circadian clock is generated by a transcription-translation feedback loop, where BMAL1 and CLOCK transcription factors of the positive arm activate the expression of CRYPTOCHROME and PERIOD (PER) genes of the negative arm as well as the circadian clock-regulated genes. In this project, we aimed at finding the interactome of PER2 protein in human U2OS osteosarcoma cell line using proximity-dependent biotin identification (BioID) technique. U2OS clones overexpressing PER2-BioID2 or BioID2 were treated with dexamethasone in order to reset the circadian rhythm, and cells were then incubated in biotin-containing media for 12 hours to label the proteins in close proximity of PER2-BioID2. Samples were collected after 36 and 48 hours of the resetting to identify the labeled proteins by mass spectrometry. In addition to known interactors such as CRY1 and CRY2, many novel interactors were identified. In summary, we obtained a network of PER2 interactome and confirmed some of the novel interactions using classical the co-immunoprecipitation method.
Project description:The diurnal peak of phagocytosis by the retinal pigment epithelium (RPE) of photoreceptor outer segments is under circadian control, and it is believed that this process involves interactions from both the retina and RPE. Previous studies have demonstrated that a functional circadian clock exists within multiple retinal cell types and RPE cells. Thereby, the aim of the current study was to determine whether the circadian clock in the retina and or RPE controls the diurnal phagocytic peak of photoreceptor outer segments and whether selective disruption of the circadian clock in the RPE would affect RPE cells function and the viability during aging. To that aim, we first generated and validated an RPE tissue-specific KO of the essential clock gene, Bmal1, and then we determined the daily rhythm in phagocytic activity by the RPE in mice lacking a functional circadian clock in the retina or RPE. Then using electroretinography, spectral domain-optical coherence tomography, and optomotor response measurements of visual function we determined the effect of Bmal1 removal in young (6-month-old) and old (18-months old) mice. RPE morphology and lipofuscin accumulation was also determined in young and old mice. Our data show that the circadian clock in the RPE controls the daily diurnal phagocytic peak of POS. Surprisingly, the lack of a functional RPE circadian clock or the diurnal phagocytic peak does not result in any detectable age-related degenerative phenotype in the retina or RPE. Thus, our results demonstrate that the circadian clock in the RPE controls the daily peak in the phagocytic activity. However, the loss of the circadian clock in the RPE does not result in deterioration of photoreceptors or the RPE during aging.
Project description:Using larval zebrafish as a model system, we applied a genome-wide transcriptome approach that allowed us to investigate circadian gene expression that can be associated with various tissues and cell types. Our analysis of circadian gene regulatory network revealed a general principle: circadian clock controls diverse aspects of circadian physiology through transcriptional cascade of transcription factors (TFs). As a proof of this principle, we focused on microphthalmia-associated transcription factor a (mitfa), a dark-induced TF controlling melanogenesis in melanocytes. We demonstrated experimentally that there is a circadian rhythm of melanin synthesis mediated by mitfa. The circadian rhythm of mitfa is in turn driven by both endogenous clock and external light/dark cycle. The circadian rhythm of melanin synthesis may play an important role in zebrafish’s adaptation to daily cycle of lighting condition in the environment.
Project description:Regulatory T cells (Treg cells) are important to maintain self-tolerance. In tissues, Treg cells can perform non-classical functions, for example, they are implicated in regulating metabolic processes in the adipose tissue. Their function in the liver is less well understood. We found here that Treg cells are important to secure the peripheral hepatic circadian rhythm of core-clock regulators and clock-controlled genes. Undisturbed metabolism in the liver required the presence of Treg cells and was especially important in the early postnatal phase, a distinct time period at around day 10, when the liver had not fully matured and Treg cells proliferated and accumulated in the liver-tissue. Our findings highlight a critical role for Treg cells to establish and maintain liver homeostasis.
Project description:Using larval zebrafish as a model system, we applied a genome-wide transcriptome approach that allowed us to investigate circadian gene expression that can be associated with various tissues and cell types. Our analysis of circadian gene regulatory network revealed a general principle: circadian clock controls diverse aspects of circadian physiology through transcriptional cascade of transcription factors (TFs). As a proof of this principle, we focused on microphthalmia-associated transcription factor a (mitfa), a dark-induced TF controlling melanogenesis in melanocytes. We demonstrated experimentally that there is a circadian rhythm of melanin synthesis mediated by mitfa. The circadian rhythm of mitfa is in turn driven by both endogenous clock and external light/dark cycle. The circadian rhythm of melanin synthesis may play an important role in zebrafishM-bM-^@M-^Ys adaptation to daily cycle of lighting condition in the environment. Total RNA of larval sample was extracted using Trizol (Invitrogen) according to the manufacturerM-bM-^@M-^Ys instruction. The quantity and quality of the RNA samples were assessed with a NanoDrop ND-1000 spectrometer (NanoDrop Technologies) and an Agilent 2100 bioanalyzer (Agilent). 12 LD RNA samples and 12 DD RNA samples were used for Agilent whole zebrafish 4x44K microarray, which contains 43,603 probes for a whole-genome transcriptional profile. Morpholinos oligonucleotides (MOs) were purchased from Gene Tools. All MOs except standard control were designed to target the start codon region of the genes. MOs were used at the following final doses: clock MO, 2.5 ng; mitfa MO, 9 ng or 13ng (microarray analysis). MOs were pressure-injected into 1- to 2-cell stage embryos at a volume of 1nl using Picospritzer II injectors as previously described (Janik et al. 2000). Each MO sample contained 40 individually treated larvae. Then the sample are collected and microarray are conducted just as before.
Project description:Circadian rhythms are daily physiological and behavioral changes governed by an internal molecular clock, and dysfunctions in circadian rhythms have long been associated with various neurodegenerative diseases. Abnormal sleep-wake cycle often precedes the onset of cognitive and motor symptoms in patients, while the pathological changes may further exacerbate the disturbance in circadian cycle. It is unclear whether dysregulated circadian rhythm is a consequence of, or a contributing factor for, neurodegeneration. In addition, the evidence directly connecting the neurodegeneration-associated proteins to core circadian clock gene expression remains sparse. Here we show that FUS, a RNA-binding protein implicated in the pathogenesis of ALS and frontotemporal dementia, exhibits a bi-directional regulation with circadian rhythm. Our meta-analysis of RNAseq datasets and subsequent biochemical analysis revealed FUS as a gene regulated by circadian oscillation. Furthermore, NR1D1 binds the FUS promoter and regulates the amplitude of FUS oscillation. Meanwhile, FUS is recruited by transcriptional co-repressor PSF, and is found in the same complex as Bmal-Clock to repress Per2 expression. More strikingly, in cells and brain tissues from homozygous knock-in rats, the pathogenic R521C mutant FUS significantly alters the oscillation patterns of core circadian genes even at young age. Therefore, our results have revealed a novel bi-directional mechanism whereby dysregulated circadian clock and FUS expression may exacerbate neurodegeneration via mutual influence.