CHRONO and DEC1/DEC2 compensate for lack of CRY1/CRY2 in expression of coherent circadian rhythm but not in generation of circadian oscillation in the neonatal mouse SCN

AbstractClock genes Cry1 and Cry2, inhibitory components of core molecular feedback loop, are regarded as critical molecules for the circadian rhythm generation in mammals. A double knockout of Cry1 and Cry2 abolishes the circadian behavioral rhythm in adult mice under constant darkness. However, robust circadian rhythms in PER2::LUC expression are detected in the cultured suprachiasmatic nucleus (SCN) of Cry1/Cry2 deficient neonatal mice and restored in adult SCN by co-culture with wild-type neonatal SCN. These findings led us to postulate the compensatory molecule(s) for Cry1/Cry2 deficiency in circadian rhythm generation. We examined the roles of Chrono and Dec1/Dec2 proteins, the suppressors of Per(s) transcription similar to CRY(s). Unexpectedly, knockout of Chrono or Dec1/Dec2 in the Cry1/Cry2 deficient mice did not abolish but decoupled the coherent circadian rhythm into three different periodicities or significantly shortened the circadian period in neonatal SCN. DNA microarray analysis for the SCN of Cry1/Cry2 deficient mice revealed substantial increases in Per(s), Chrono and Dec(s) expression, indicating disinhibition of the transactivation by BMAL1/CLOCK. Here, we conclude that Chrono and Dec1/Dec2 do not compensate for absence of CRY1/CRY2 in the circadian rhythm generation but contribute to the coherent circadian rhythm expression in the neonatal mouse SCN most likely through integration of cellular circadian rhythms.

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Circadian Rhythm: Potential Therapeutic Target for Atherosclerosis and Thrombosis

International Journal of Molecular Sciences ◽

10.3390/ijms22020676 ◽

2021 ◽

Vol 22 (2) ◽

pp. 676

Author(s):

Andy W. C. Man ◽

Huige Li ◽

Ning Xia

Keyword(s):

Circadian Rhythm ◽

Cardiovascular Diseases ◽

Circadian Rhythms ◽

Circadian Clock ◽

Therapeutic Target ◽

Environmental Changes ◽

Clock Genes ◽

Vascular System ◽

Peripheral Tissues ◽

Inflammatory Processes

Every organism has an intrinsic biological rhythm that orchestrates biological processes in adjusting to daily environmental changes. Circadian rhythms are maintained by networks of molecular clocks throughout the core and peripheral tissues, including immune cells, blood vessels, and perivascular adipose tissues. Recent findings have suggested strong correlations between the circadian clock and cardiovascular diseases. Desynchronization between the circadian rhythm and body metabolism contributes to the development of cardiovascular diseases including arteriosclerosis and thrombosis. Circadian rhythms are involved in controlling inflammatory processes and metabolisms, which can influence the pathology of arteriosclerosis and thrombosis. Circadian clock genes are critical in maintaining the robust relationship between diurnal variation and the cardiovascular system. The circadian machinery in the vascular system may be a novel therapeutic target for the prevention and treatment of cardiovascular diseases. The research on circadian rhythms in cardiovascular diseases is still progressing. In this review, we briefly summarize recent studies on circadian rhythms and cardiovascular homeostasis, focusing on the circadian control of inflammatory processes and metabolisms. Based on the recent findings, we discuss the potential target molecules for future therapeutic strategies against cardiovascular diseases by targeting the circadian clock.

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Disrupted circadian rhythms in VIP- and PHI-deficient mice

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00200.2003 ◽

2003 ◽

Vol 285 (5) ◽

pp. R939-R949 ◽

Cited By ~ 232

Author(s):

Christopher S. Colwell ◽

Stephan Michel ◽

Jason Itri ◽

Williams Rodriguez ◽

J. Tam ◽

...

Keyword(s):

Circadian Rhythms ◽

Wheel Running ◽

Activity Rhythm ◽

Activity Patterns ◽

Circadian System ◽

Diurnal Rhythms ◽

Constant Darkness ◽

Light Cycle ◽

Wild Type ◽

Deficient Mice

The related neuropeptides vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) are expressed at high levels in the neurons of the suprachiasmatic nucleus (SCN), but their function in the regulation of circadian rhythms is unknown. To study the role of these peptides on the circadian system in vivo, a new mouse model was developed in which both VIP and PHI genes were disrupted by homologous recombination. In a light-dark cycle, these mice exhibited diurnal rhythms in activity which were largely indistinguishable from wild-type controls. In constant darkness, the VIP/PHI-deficient mice exhibited pronounced abnormalities in their circadian system. The activity patterns started ∼8 h earlier than predicted by the previous light cycle. In addition, lack of VIP/PHI led to a shortened free-running period and a loss of the coherence and precision of the circadian locomotor activity rhythm. In about one-quarter of VIP/PHI mice examined, the wheel-running rhythm became arrhythmic after several weeks in constant darkness. Another striking example of these deficits is seen in the split-activity patterns expressed by the mutant mice when they were exposed to a skeleton photoperiod. In addition, the VIP/PHI-deficient mice exhibited deficits in the response of their circadian system to light. Electrophysiological analysis indicates that VIP enhances inhibitory synaptic transmission within the SCN of wild-type and VIP/PHI-deficient mice. Together, the observations suggest that VIP/PHI peptides are critically involved in both the generation of circadian oscillations as well as the normal synchronization of these rhythms to light.

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Chronic Corticosterone Disrupts the Circadian Rhythm of CRH Expression and M6a RNA Methylation in the Chicken Hypothalamus

10.21203/rs.3.rs-919584/v1 ◽

2021 ◽

Author(s):

Yang Yang ◽

Wanwan Han ◽

Aijia Zhang ◽

Mindie Zhao ◽

Wei Cong ◽

...

Keyword(s):

Circadian Rhythm ◽

Circadian Rhythms ◽

Chronic Stress ◽

Hpa Axis ◽

Clock Genes ◽

Diurnal Fluctuation ◽

Opposite Pattern ◽

Rna Methylation ◽

Diurnal Patterns ◽

M6a Rna Methylation

Abstract Corticotropin-releasing hormone (CRH), the major secretagogue of the hypothalamic-pituitary-adrenal (HPA) axis, is intricately intertwined with the clock genes to regulate the circadian rhythm of various body functions. N6-methyladenosine (m6A) RNA methylation is involved in the regulation of circadian rhythm, yet it remains unknown whether CRH expression and m6A modification oscillate with the clock genes in chicken hypothalamus and how the circadian rhythms change under chronic stress. Here, we show that chronic exposure to corticosterone (CORT) eliminated the diurnal patterns of plasma CORT and melatonin levels in the chicken. The circadian rhythms of clock genes in hippocampus, hypothalamus and pituitary are all disturbed to different extent in CORT-treated chickens. The most striking changes occur in hypothalamus in which the diurnal fluctuation of CRH mRNA is flattened, together with mRNA of other feeding-related neuropeptides. Interestingly, hypothalamic m6A level oscillates in an opposite pattern to CRH mRNA, with lowest m6A level after midnight (ZT18) corresponding to the peak of CRH mRNA before dawn (ZT22). CORT diminished the circadian rhythm of m6A methylation with significantly increased level at night. Further site-specific m6A analysis on 3’UTR of CRH mRNA indicates that higher m6A on 3’UTR of CRH mRNA coincides with lower CRH mRNA at night (ZT18 and ZT22). Our results indicate that chronic stress disrupts the circadian rhythms of CRH expression in hypothalamus, leading to dysfunction of HPA axis in the chicken. RNA m6A modification is involved in the regulation of circadian rhythms in chicken hypothalamus under both basal and chronic stress conditions.

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Abstract P160: Non-invasive Method to Assess Human Circadian Rhythms

Hypertension ◽

10.1161/hyp.68.suppl_1.p160 ◽

2016 ◽

Vol 68 (suppl_1) ◽

Author(s):

Daian Chen ◽

S Justin Thomas ◽

David A Calhoun ◽

David M Pollock ◽

Jennifer S Pollock

Keyword(s):

Circadian Rhythm ◽

Circadian Rhythms ◽

Salivary Cortisol ◽

Metabolic Diseases ◽

Clock Genes ◽

Light Exposure ◽

Rna Isolation ◽

Buccal Cells ◽

Non Invasive ◽

Salivary Melatonin

Circadian rhythms are controlled by an endogenous time-keeping system oscillating approximately on a 24-h cycle under constant conditions. These rhythms depend on a network of interacting genes and proteins, including transcriptional activators such as CLOCK, NPAS2, and ARNTL (BMAL1), which induce transcription of the clock genes Period ( Per1 , Per2 , and Per3 ) and Cryptochrome ( Cry1 and Cry2 ). Human salivary cortisol and melatonin follow a clear circadian rhythm as well. Disruption of the circadian rhythm and sleep-wake cycles are considered risk factors for a variety of health problems, especially hypertension and other cardiovascular and metabolic diseases. Here we put together practical methods for assessing circadian rhythms in adult subjects conducted by each individual. This method is non-invasive, inexpensive and provides a predictive profile of an individual’s circadian rhythm related to clock-controlled gene expression in buccal cells, salivary cortisol, salivary melatonin, and subject’s activity or sleep. Subjects are instructed on how to obtain buccal cells using swabs (Whatman OmniSwab) from the inside of their cheeks and collect saliva using salivettes (Sarstedt) every 4 hours starting at 6am, for 2 consecutive days. Subjects also wear actigraphy watches (Phillips Respironics) during the 2 days, to record their activity, light exposure and estimates of sleep times. To monitor adherence to correct time point collections, each subject is given an electronic vial called eCAP (Information Mediary Corp) that records the exact time the container is opened to place samples once collected. We demonstrate feasibility to extract up to 150ng/μl of RNA (Ambion RNAqueous-Micro Total RNA Isolation Kit) from buccal cells swabs. Salivary melatonin and cortisol are measured by radioimmunoassay (Buhlmann Lab) with melatonin peak levels ranging from 14 to 23 pg/ml and cortisol peak levels ranging from 10 to 24 ng/ml. We suggest that buccal cell expression of clock-controlled genes, salivary melatonin, salivary cortisol, and actigraphy data are valuable in providing reliable assessment of human circadian rhythm profiles under a variety of conditions.

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Enhanced effect of daytime restricted feeding on the circadian rhythm of streptozotocin-induced type 2 diabetic rats

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00651.2011 ◽

2012 ◽

Vol 302 (9) ◽

pp. E1027-E1035 ◽

Cited By ~ 9

Author(s):

Tao Wu ◽

Fen ZhuGe ◽

Lu Sun ◽

Yinhua Ni ◽

Ou Fu ◽

...

Keyword(s):

Circadian Rhythm ◽

Pineal Gland ◽

Circadian Clock ◽

Clock Genes ◽

Activity Rhythm ◽

Diabetic Rats ◽

Restricted Feeding ◽

Behavioral Rhythm ◽

Type 2 Diabetic

There is increasing awareness of the link between impaired circadian clocks and multiple metabolic diseases. However, the impairment of the circadian clock by type 2 diabetes has not been fully elucidated. To understand whether and how the function of circadian clock is impaired under the diabetic condition, we examined not only the expression of circadian genes in the heart and pineal gland but also the behavioral rhythm of type 2 diabetic and control rats in both the nighttime restricted feeding (NRF) and daytime restricted feeding (DRF) conditions. In the NRF condition, the circadian expression of clock genes in the heart and pineal gland was conserved in the diabetic rats, being similar to that in the control rats. DRF shifted the circadian phases of peripheral clock genes more efficiently in the diabetic rats than those in the control rats. Moreover, the activity rhythm of rats in the diabetic group was completely shifted from the dark phase to the light phase after 5 days of DRF treatment, whereas the activity rhythm of rats in the control group was still under the control of the suprachiasmatic nucleus (SCN) after the same DRF treatment. Furthermore, the serum glucose rhythm of type 2 diabetic rats was also shifted and controlled by the external feeding schedule, ignoring the SCN rhythm. Therefore, DRF shows stronger effect on the reentrainment of circadian rhythm in the type 2 diabetic rats, suggesting that the circadian system in diabetes is unstable and more easily shifted by feeding stimuli.

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The Circadian Clock Is Sustained in the Thyroid Gland of VIP Receptor 2 Deficient Mice

Frontiers in Endocrinology ◽

10.3389/fendo.2021.737581 ◽

2021 ◽

Vol 12 ◽

Author(s):

Birgitte Georg ◽

Jan Fahrenkrug ◽

Henrik L. Jørgensen ◽

Jens Hannibal

Keyword(s):

Circadian Clock ◽

Clock Genes ◽

Hormone Secretion ◽

Heart Rhythm ◽

Thyroid Stimulating Hormone ◽

Constant Darkness ◽

Receptor Signaling ◽

Knockout Animals ◽

The Impact ◽

Deficient Mice

VIP/VPAC2-receptor signaling is crucial for functioning of the circadian clock in the suprachiasmatic nucleus (SCN) since the lack results in disrupted synchrony between SCN cells and altered locomotor activity, body temperature, hormone secretion and heart rhythm. Endocrine glands, including the thyroid, show daily oscillations in clock gene expression and hormone secretion, and SCN projections target neurosecretory hypothalamic thyroid-stimulating hormone (TSH)-releasing hormone cells. The aim of the study was to gain knowledge of mechanisms important for regulation of the thyroid clock by evaluating the impact of VIP/VPAC2-receptor signaling. Quantifications of mRNAs of three clock genes (Per1, Per2 and Bmal1) in thyroids of wild type (WT) and VPAC2-receptor deficient mice were done by qPCR. Tissues were taken every 4th h during 24-h 12:12 light-dark (LD) and constant darkness (DD) periods, both genders were used. PER1 immunoreactivity was visualized on sections of both WT and VPAC2 lacking mice during a LD cycle. Finally, TSH and the thyroid hormone T4 levels were measured in the sera by commercial ELISAs. During LD, rhythmic expression of all three mRNA was found in both the WT and knockout animals. In VPAC2-receptor knockout animals, the amplitudes were approximately halved compared to the ones in the WT mice. In the WT, Per1 mRNA peaked around “sunset”, Per2 mRNA followed with approximately 2 h, while Bmal1 mRNA was in antiphase with Per1. In the VPAC2 knockout mice, the phases of the mRNAs were advanced approximately 5 h compared to the WT. During DD, the phases of all the mRNAs were identical to the ones found during LD in both groups of mice. PER1 immunoreactivity was delayed compared to its mRNA and peaked during the night in follicular cells of both the thyroid and parathyroid glands in the WT animals. In WT animals, TSH was high around the transition to darkness compared to light-on, while T4 did not change during the 24 h cycle. In conclusion, sustained and identical rhythms (phases and amplitudes) of three clock genes were found in VPAC2 deficient mice during LD and DD suggesting high degree of independence of the thyroid clock from the master SCN clock.

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Purine Catabolism Shows a Dampened Circadian Rhythmicity in a High-fat Diet-Induced Mouse Model of Obesity

Molecules ◽

10.3390/molecules24244524 ◽

2019 ◽

Vol 24 (24) ◽

pp. 4524 ◽

Cited By ~ 1

Author(s):

Runbin Sun ◽

Jingqiu Huang ◽

Na Yang ◽

Jun He ◽

Xiaoyi Yu ◽

...

Keyword(s):

Circadian Rhythms ◽

Mouse Model ◽

Nutritional Status ◽

Metabolic Pathways ◽

High Fat Diet ◽

Clock Genes ◽

Circadian Rhythmicity ◽

Circadian Oscillation ◽

High Fat ◽

Purine Catabolism

High-calorie diet, circadian rhythms and metabolic features are intimately linked. However, the mediator(s) between nutritional status, circadian rhythms and metabolism remain largely unknown. This article aims to clarify the key metabolic pathways bridging nutritional status and circadian rhythms based on a combination of metabolomics and molecular biological techniques. A mouse model of high-fat diet-induced obesity was established and serum samples were collected in obese and normal mice at different zeitgeber times. Gas chromatography/mass spectrometry, multivariate/univariate data analyses and metabolic pathway analysis were used to reveal changes in metabolism. Metabolites involved in the metabolism of purines, carbohydrates, fatty acids and amino acids were markedly perturbed in accordance with circadian related variations, among which purine catabolism showed a typical oscillation. What’s more, the rhythmicity of purine catabolism dampened in the high-fat diet group. The expressions of clock genes and metabolic enzymes in the liver were measured. The mRNA expression of Xanthine oxidase (Xor) was highly correlated with the rhythmicity of Clock, Rev-erbα and Bmal1, as well as the metabolites involved in purine catabolism. These data showed that a high-fat diet altered the circadian rhythm of metabolic pathways, especially purine catabolism. It had an obvious circadian oscillation and a high-fat diet dampened its circadian rhythmicity. It was suggested that circadian rhythmicity of purine catabolism is related to circadian oscillations of expression of Xor, Uox and corresponding clock genes.

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Abstract 13133: Impact of Circadian Rhythm Disorders on Reparative Angiogenesis

Circulation ◽

10.1161/circ.142.suppl_3.13133 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Kazuhito Tsuzuki ◽

Yuuki Shimizu ◽

Zhongyue Pu ◽

Junya Suzuki ◽

Shukuro Yamaguchi ◽

...

Keyword(s):

Circadian Rhythm ◽

Clock Genes ◽

Blood Perfusion ◽

Jet Lag ◽

Double Knockout ◽

Tissue Ischemia ◽

Circadian Rhythm Disorder ◽

Rhythm Disorder ◽

Reparative Angiogenesis ◽

Circadian Rhythm Disorders

Introduction: Circadian rhythm disorder seen in shift-worker or jet-lag is major social health concerns in advanced industrialized countries. The aim of this study was to examine if circadian rhythm disorders would influence on angiogenesis and blood perfusion recovery in a mouse model of hind limb ischemia (HLI). Methods and Results: First, we established a jet-lag model in C57BL/6J (wild type; WT) mice (8-10 weeks old, N=10 for each) using a light controlled isolation box. Mice were exposed to advanced 8-hr light phase once every 4 days in a jet-lag group as previously described. Conversely, control mice were kept a regular condition of LD 12:12 (12-hr light and 12-hr dark). Then, we surgically induced HLI in each group. The results showed that the condition jet-lag deteriorated capillary formation detected by CD31-immunohistochemistry at post-operative day (POD) 28 and tissue blood perfusion recovery demonstrated by laser Doppler perfusion imaging (LDPI) in HLI. The expression of clock genes (i.e. Clock, Bmal1, Per2, Cry1 and 2 ) in ischemic muscles were regulated by jet-lag condition at POD7.Next, we examined whether inhibition of clock gene had any effects on angiogenesis. For this study, we focused on Cryptochrome ( Cry ), which is well known as one of the core-loop forming clock genes producing circadian rhythm in mammals. Our loss-of-function study revealed that the abilities of proliferation, migration and tube formation were significantly inhibited by CRY1 and CRY2 double knockdown in HUVECs. Interestingly, although the knockdown of CRY1 and CRY2 changed the mRNA expression of PERIOD2 , it did not affect those of BMAL1 and CLOCK in HUVECs. Finally, we tested if Cry1 and Cry2 double knockout ( Cry1/2 -DKO) mice of HLI models displayed worse blood perfusion recoveries with deterioration of angiogenesis. Cry1/2 -DKO mice were reported to display circadian rhythm disorder in previous reports. As results, compared with control WT mice, Cry1/2 -DKO mice revealed suppressed capillary density and tissue blood perfusion recovery in HLI model. Conclusion: Our data suggest that a maintenance of circadian rhythm plays an important role in reparative angiogenesis of the tissue ischemia model.

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Vasopressin receptor V1a regulates circadian rhythms of locomotor activity and expression of clock-controlled genes in the suprachiasmatic nuclei

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.90463.2008 ◽

2009 ◽

Vol 296 (3) ◽

pp. R824-R830 ◽

Cited By ~ 75

Author(s):

Jia-Da Li ◽

Katherine J. Burton ◽

Chengkang Zhang ◽

Shuang-Bao Hu ◽

Qun-Yong Zhou

Keyword(s):

Circadian Rhythm ◽

Circadian Rhythms ◽

Circadian Oscillation ◽

Fast Fourier Transformation ◽

Mrna Levels ◽

Suprachiasmatic Nuclei ◽

Prokineticin 2 ◽

Locomotor Activities ◽

Core Genes

The suprachiasmatic nuclei (SCN) serve as the principal circadian pacemakers that coordinate daily cycles of behavior and physiology for mammals. A network of transcriptional and translational feedback loops underlies the operating molecular mechanism for circadian oscillation within the SCN neurons. It remains unclear how timing information is transmitted from SCN neurons to eventually evoke circadian rhythms. Intercellular communication between the SCN and its target neurons is critical for the generation of coherent circadian rhythms. At the molecular level, neuropeptides encoded by clock-controlled genes have been indicated as important output mediators. Arginine vasopressin (AVP) is the product of one such clock-controlled gene. Previous studies have demonstrated a circadian rhythm of AVP levels in the cerebrospinal fluid and the SCN. The physiological effects of AVP are mediated by three types of AVP receptors, designated as V1a, V1b, and V2. In this study, we report that V1a mRNA levels displayed a circadian rhythm in the SCN, peaking during night hours. The circadian rhythmicity of locomotor activities was significantly reduced in V1a-deficient ( V1a−/−) mice (50–75% reduction in the power of fast Fourier transformation). However, the light masking and light-induced phase shift effects are intact in V1a−/− mice. Whereas the expression of clock core genes was unaltered, the circadian amplitude of prokineticin 2 ( PK2) mRNA oscillation was attenuated in the SCN of V1a−/− mice (∼50% reduction in the peak levels). In vitro experiments demonstrated that AVP, acting through V1a receptor, was able to enhance the transcriptional activity of the PK2 promoter. These studies thus indicate that AVP-V1a signaling plays an important role in the generation of overt circadian rhythms.

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REGULATION BY THE PITUITARY GLAND OF CIRCADIAN RHYTHMS IN THE HAMSTER

Journal of Endocrinology ◽

10.1677/joe.0.0850017 ◽

1980 ◽

Vol 85 (1) ◽

pp. 17-25 ◽

Cited By ~ 20

Author(s):

IRVING ZUCKER ◽

CATHERINE P. CRAMER ◽

E. L. BITTMAN

Keyword(s):

Circadian Rhythm ◽

Locomotor Activity ◽

Pituitary Gland ◽

Activity Cycle ◽

Active Phase ◽

Circadian Oscillation ◽

Constant Darkness ◽

Subjective Night ◽

The Difference

SUMMARY Locomotor activity of male hamsters was recorded during long-term exposure to constant light (LL), constant darkness (DD) and during entrainment (modification of a circadian rhythm) to a 14 h light: 10 h darkness photoperiod (14L: 10D). In LL the period of the activity cycle was substantially longer in hypophysectomized than in control animals. This difference persisted during tests in DD. Although hypophysectomy reduced the duration of the active phase in some hamsters, overall the difference between the groups was not significant. The phase angle of onset of activity in 14L: 10D was not affected by hypophysectomy. Hypophysectomized female hamsters tested in DD had activity rhythms whose periods were longer than those of control animals; they were also significantly less active than corresponding controls during the first 4 h of the subjective night but the duration of the active phase did not differ significantly between the groups. These results suggest that hormones of the pituitary-gonadal axis modulate the period of circadian oscillation.

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