Project description:The circadian clock attunes metabolism to daily energy cycles, but how it regulates metabolic tissue maturation is not well understood. Here we show that DEC1, a clock transcription factor induced in adult islet β cells, coordinates their glucose responsiveness by synchronizing energetic and secretory rhythms. DEC1 binds maturity-linked genes regulating integration of energy metabolism and insulin exocytosis, and β-cell Dec1 ablation disrupts their transcription synchrony. Dec1-disrupted mice develop lifelong glucose intolerance and insulin deficiency, despite normal islet formation and intact CLOCK/BMAL1 genes. Metabolic dysfunction upon β-cell Dec1 loss stems from poor coupling of insulin secretion to glucose metabolism, reminiscent of fetal/neonatal immaturity. We find that stunted maturation reflects an energetic deficit, marked by reduced glycolysis and compromised mitochondrial dynamics and respiration, which is rescued by increasing metabolic flux. Thus, DEC1 links circadian clockwork to β-cell metabolic maturation, revealing a hierarchy for how the clock programs metabolic tissue specialization.
Project description:Glis3 is expressed in pancreatic beta and PP cells. To identify down stream target genes of Glis3, we performed microarray analysis using pancreas total RNAs from 1 week-old WT and Glis3KO2 mice. insulin and pancreatic polypeptide (Ppy) was significantly decreased together with several other β cell markers, Glut2 and MafA by microarray analysis. Immunohistochemistry, QRT-PCR, and transmission electron microscopy indicated that postnatal Glis3KO2 pancreas still contains a large population of β cells that express Pdx-1, Nkx6.1, and Isl-1; however, insulin production and secretory granules were greatly reduced in these cells. In addition, chromogranin A (ChgA) and Urocortin 3, which are associated with mature β cells, was dramatically decreased in Glis3KO2 pancreas. These observations suggest that Glis3 plays a critical role in the maturation of pancreatic β cell phenotype. Pancreatic total RNAs were purified from 4 WT and 4 Glis3KO2 at 1 week old age. Then the samples were applied to Agilent mouse genome chip.
Project description:The goal of this review was to seek a better understanding of the function and differential expression of circadian clock genes during the reproductive process. Through a discussion of how the circadian clock is involved in these steps, the identification of new clinical targets for sleep disorder-related diseases, such as reproductive failure, will be elucidated. Here, we focus on recent research findings regarding circadian clock regulation within the reproductive system, shedding new light on circadian rhythm-related problems in women. Discussions on the roles that circadian clock plays in these reproductive processes will help identify new clinical targets for such sleep disorder-related diseases.
Project description:Glis3 is expressed in pancreatic beta and PP cells. To identify down stream target genes of Glis3, we performed microarray analysis using pancreas total RNAs from 1 week-old WT and Glis3KO2 mice. insulin and pancreatic polypeptide (Ppy) was significantly decreased together with several other β cell markers, Glut2 and MafA by microarray analysis. Immunohistochemistry, QRT-PCR, and transmission electron microscopy indicated that postnatal Glis3KO2 pancreas still contains a large population of β cells that express Pdx-1, Nkx6.1, and Isl-1; however, insulin production and secretory granules were greatly reduced in these cells. In addition, chromogranin A (ChgA) and Urocortin 3, which are associated with mature β cells, was dramatically decreased in Glis3KO2 pancreas. These observations suggest that Glis3 plays a critical role in the maturation of pancreatic β cell phenotype.
Project description:BackgroundSkipping breakfast is associated with dysmenorrhea in young women. This suggests that the delay of food intake in the active phase impairs uterine functions by interfering with circadian rhythms.ObjectivesTo examine the relation between the delay of feeding and uterine circadian rhythms, we investigated the effects of the first meal occasion in the active phase on the uterine clock.MethodsZeitgeber time (ZT) was defined as ZT0 (08:45) with lights on and ZT12 (20:45) with lights off. Young female mice (8 wk of age) were divided into 3 groups: group I (ad libitum consumption), group II (time-restricted feeding during ZT12-16, initial 4 h of the active period), and group III (time-restricted feeding during ZT20-24, last 4 h of the active period, a breakfast-skipping model). After 2 wk of dietary restriction, mice in each group were killed at 4-h intervals and the expression profiles of uterine clock genes, Bmal1 (brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein 1), Per1 (period circadian clock 1), Per2, and Cry1 (cryptochrome 1), were examined.ResultsqPCR and western blot analyses demonstrated synchronized circadian clock gene expression within the uterus. Immunohistochemical analysis confirmed that BMAL1 protein expression was synchronized among the endometrium and myometrium. In groups I and II, mRNA expression of Bmal1 was elevated after ZT12 at the start of the active phase. In contrast, Bmal1 expression was elevated just after ZT20 in group III, showing that the uterine clock rhythm had shifted 8 h backward. The changes in BMAL1 protein expression were confirmed by western blot analysis.ConclusionsThis study is the first to indicate that time-restricted feeding regulates a circadian rhythm of the uterine clock that is synchronized throughout the uterine body. These findings suggest that the uterine clock system is a new candidate to explain the etiology of breakfast skipping-induced uterine dysfunction.
Project description:Development of cell replacement therapies in diabetes requires understanding of the molecular underpinnings of β-cell maturation. The circadian clock regulates diverse cellular functions important for regulation of β-cell function and turnover. However, postnatal ontogenesis of the islet circadian clock and its potential role in β-cell maturation remain unknown. To address this, we studied wild-type Sprague-Dawley as well as Period1 luciferase transgenic (Per1:LUC) rats to determine circadian clock function, clock protein expression, and diurnal insulin secretion during islet development and maturation process. We additionally studied β-cell-specific Bmal1-deficient mice to elucidate a potential role of this key circadian transcription factor in β-cell functional and transcriptional maturation. We report that emergence of the islet circadian clock 1) occurs during the early postnatal period, 2) depends on the establishment of global behavioral circadian rhythms, and 3) leads to the induction of diurnal insulin secretion and gene expression. Islet cell maturation was also characterized by induction in the expression of circadian transcription factor BMAL1, deletion of which altered postnatal development of glucose-stimulated insulin secretion and the associated transcriptional network. Postnatal development of the islet circadian clock contributes to early-life β-cell maturation and should be considered for optimal design of future β-cell replacement strategies in diabetes.
Project description:Photosynthesis in chloroplasts during the day and mitochondrial respiration during the night execute nearly opposing reactions that are coordinated with the internal cellular status and the external conditions. Here, we describe a mechanism by which the Arabidopsis clock component TIMING OF CAB EXPRESSION1 (TOC1) contributes to the diurnal regulation of metabolism. Proper expression of TOC1 is important for sustaining cellular energy and for the diel and circadian oscillations of sugars, amino acids and tricarboxylic acid (TCA) cycle intermediates. TOC1 binds to the promoter of the TCA-related gene FUMARASE 2 to repress its expression at night, which results in decreased fumarate accumulation in TOC1 over-expressing plants and increased in toc1-2 mutant. Genetic interaction studies confirmed that over-expression of FUMARASE 2 in TOC1 over-expressing plants alleviates the molecular and physiological energy-deprivation phenotypes of TOC1 over-expressing plants. Thus, we propose that the tandem TOC1-FUMARASE 2 is one of the mechanisms that contribute to the regulation of plant metabolism during the day and night.
Project description:Congenital and developmental craniofacial deformities often cause bone defects, misalignment, and soft tissue asymmetry, which can lead to facial function and morphologic abnormalities, especially among children born with cleft lip and palate. Joint efforts from oral maxillofacial surgery, oral implantology, and cosmetic surgery are often required for diagnosis and treatment. As one of the most widely performed treatment methods, implant-supported cranio-maxillofacial prostheses have been widely applied in the course of treatment. Therefore, stability of peri-implant bone tissue is crucial for the long-term success of treatment and patients' quality of life. The circadian clock component brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) was found to be involved in the cell fate of bone marrow mesenchymal stem cells, which were essential in the fixation of titanium implants. This study aimed to investigate the effect of BMAL1 on osteogenesis in osseointegration, providing a brand new solution to increase bone implant conjunction efficiency and implant stability, paving the way for a long-term satisfactory therapy outcome.
Project description:Mammalian circadian clocks have a hierarchical organization, governed by the suprachiasmatic nucleus (SCN) in the hypothalamus. The brain itself contains multiple loci that maintain autonomous circadian rhythmicity, but the contribution of the non-SCN clocks to this hierarchy remains unclear. We examine circadian oscillations of clock gene expression in various brain loci and discovered that in mouse, robust, higher amplitude, relatively faster oscillations occur in the choroid plexus (CP) compared to the SCN. Our computational analysis and modeling show that the CP achieves these properties by synchronization of "twist" circadian oscillators via gap-junctional connections. Using an in vitro tissue coculture model and in vivo targeted deletion of the Bmal1 gene to silence the CP circadian clock, we demonstrate that the CP clock adjusts the SCN clock likely via circulation of cerebrospinal fluid, thus finely tuning behavioral circadian rhythms.