Objective: To investigate the correlation between CLOCK and BMAL1 genes and MEN2 medullary thyroid carcinoma (MTC). Methods: Thirteen cases with MEN2 MTC and thirteen cases with non-MEN2 MTC were selected who were treated in the Yantai Yuhuangding Hospital between January 2013 and September 2021. Clinical indicators such as blood calcitonin level, tumor diameter and metastatic lymph node of patients were collected. The expression differences of CLOCK and BMAL1 between MEN2 MTC and para-carcinoma tissue as well as between MEN2 MTC and non-MEN2 MTC were detected by immunohistochemistry and qPCR. The correlation between lymph node metastasis and CLOCK or BMAL1 expression was analyzed. Protein-protein interaction (PPI) network analysis combined with qPCR and correlation analysis was used to explore the expression regulation relationship between RET and circadian clock genes. The rhythm disorder of MEN2 cells was verified by lipopolysaccharide cell stimulation experiment after dexamethasone rhythm synchronization. Results: MEN2 MTC exhibited typical RET gene mutation. The mean blood calcitonin level, the tumor diameter and the number of metastatic lymph nodes of patients with MEN2 MTC were higher than those of patients with non-MEN2 MTC (t value was 2.76, 2.53, 2.26, all P<0.05). Immunohistochemical results showed that the expression levels of CLOCK and BMAL1 in MEN2 MTC were higher than those in non-MEN2 MTC, while negatively expressed in para-cancerous thyroid follicle. qPCR displayed that the expression of CLOCK gene in cancer tissues was higher than that in non-MEN2 MTC and para-cancerous tissues (t value was 2.68 and 2.86, all P<0.05); the expression of BMAL1 gene in MEN2 MTC was higher than that in non-MEN2 MTC and para-cancerous tissues (t value was 2.21 and 2.35, all P<0.05). Correlation analysis showed that the expression levels of CLOCK and BMAL1 genes were positively correlated with the number of lymph node metastases in patients with MEN2 MTC (r=0.65, P<0.001; r=0.52, P=0.005). PPI network analysis indicated that the expression of CLOCK gene was positively correlated with the abnormal expression of RET gene (r=0.96, P<0.001). With lipopolysaccharide to stimulate cultured cells in vitro after dexamethasone rhythm synchronization, the expressions of CLOCK and BMAL1 in MEN2 MTC cells (0.47±0.22 and 2.60±1.48) at 12 hours of synchronization were significantly lower than those in para-cancerous tissues (1.70±1.62 and 8.23±2.52), the difference was statistically significant(t=5.04, P=0.007; t=3.34, P=0.029). Conclusion: CLOCK and BMAL1 are correlated with the occurrence and development of MEN2 MTC, and may be potential targets for the development of new therapeutic strategies for MEN2 MTC.
ARNTL Transcription Factors/genetics* ; CLOCK Proteins/genetics* ; Calcitonin ; Carcinoma, Neuroendocrine/genetics* ; Dexamethasone ; Humans ; Lipopolysaccharides ; Lymphatic Metastasis ; Multiple Endocrine Neoplasia Type 2a/genetics* ; Thyroid Neoplasms/surgery*

Circadian clock is an internal autonomous time-keeping system, including central clocks located in the suprachiasmatic nucleus (SCN) and peripheral clocks. The molecular circadian clock consists of a set of interlocking transcriptional-translational feedback loops that take the clock-controlled genes 24 h to oscillate. The core mechanism of molecular circadian clock is that CLOCK/BMAL1 dimer activates the transcription of cryptochromes (CRYs) and Periods (PERs), which act as transcriptional repressors of further CLOCK/BMAL1-mediated transcription. In addition to this basic clock, there is an additional sub-loop of REV-ERBα and RORα regulating the transcription of BMAL1. Approximately 80% protein-coding genes demonstrate significant rhythmicity. The earth rotation is responsible for the generation of the daily circadian rhythms. To coordinate metabolic balance and energy availability, almost all organisms adapt to the rhythm. Studies have shown that circadian clock integrating with metabolic homeostasis increases the efficiency of energy usage and coordinates with different organs in order to adapt to internal physiology and external environment soon. As the central organ of metabolism, the liver performs various physiological activities nearly all controlled by the circadian clock. There are multiple interactive regulation mechanisms between the circadian clock and the regulation of liver metabolism. The misalignment of metabolism with tissue circadian is identified as a high-risk factor of metabolic diseases. This article reviews the recent studies on circadian physiological regulation of liver glucose, lipid and protein metabolism and emphasizes oscillation of mitochondrial function. We also take an outlook for new methods and application of circadian clock research in the future.
CLOCK Proteins ; Circadian Clocks/genetics* ; Circadian Rhythm ; Liver ; Suprachiasmatic Nucleus

BACKGROUND: Exposure to the ionizing radiation (IR) encountered outside the magnetic field of the Earth poses a persistent threat to the reproductive functions of astronauts. The potential effects of space IR on the circadian rhythms of male reproductive functions have not been well characterized so far. METHODS: Here, we investigated the circadian effects of IR exposure (3 Gy X-rays) on reproductive functional markers in mouse testicular tissue and epididymis at regular intervals over a 24-h day. For each animal, epididymis was tested for sperm motility, and the testis tissue was used for daily sperm production (DSP), testosterone levels, and activities of testicular enzymes (glucose-6-phosphate dehydrogenase (G6PDH), sorbitol dehydrogenase (SDH), lactic dehydrogenase (LDH), and acid phosphatase (ACP)), and the clock genes mRNA expression such as Clock, Bmal1, Ror-α, Ror-β, or Ror-γ. RESULTS: Mice exposed to IR exhibited a disruption in circadian rhythms of reproductive markers, as indicated by decreased sperm motility, increased daily sperm production (DSP), and reduced activities of testis enzymes such as G6PDH, SDH, LDH, and ACP. Moreover, IR exposure also decreased mRNA expression of five clock genes (Clock, Bmal1, Ror-α, Ror-β, or Ror-γ) in testis, with alteration in the rhythm parameters. CONCLUSION These findings suggested potential health effects of IR exposure on reproductive functions of male astronauts, in terms of both the daily overall level as well as the circadian rhythmicity.
ARNTL Transcription Factors/genetics* ; Acid Phosphatase ; Animals ; CLOCK Proteins/genetics* ; Circadian Rhythm/radiation effects* ; Epididymis/radiation effects* ; Gene Expression/radiation effects* ; Genitalia, Male/radiation effects* ; Glucosephosphate Dehydrogenase ; L-Iditol 2-Dehydrogenase ; L-Lactate Dehydrogenase ; Male ; Mice ; Mice, Inbred C57BL ; Models, Animal ; Nuclear Receptor Subfamily 1, Group F, Member 1/genetics* ; Nuclear Receptor Subfamily 1, Group F, Member 2/genetics* ; Nuclear Receptor Subfamily 1, Group F, Member 3/genetics* ; RNA, Messenger/genetics* ; Radiation Exposure ; Radiation, Ionizing ; Reproductive Physiological Phenomena/radiation effects* ; Sperm Motility/radiation effects* ; Spermatozoa/radiation effects* ; Testis/radiation effects*

OBJECTIVETo study the changes of miRNA expression in the pineal gland of neonatal rats with hypoxic-ischemic brain damage (HIBD) and the possible roles of miRNA in the pathogenesis of circadian rhythm disturbance after HIBD.

METHODSSeven-day-old Sprague-Dawley (SD) rats were randomly divided into 2 groups: HIBD and sham-operated. HIBD was induced according to the Rice-Vannucci method. The pineal glands were obtained 24 hours after the HIBD event. The expression profiles of miRNAs were determined using GeneChip technigue and quantitative real-time PCR (RT-PCR). Then the miRNA which was highly expressed was selected. The expression levels of the chosen miRNA were detected in different tissues (lungs, intestines, stomach, kidneys, cerebral cortex, pineal gland). RT-PCR analysis was performed to measure the expression profiles of the chosen miRNA and the targeted gene Clock mRNA in the pineal gland at 0, 24, 48 and 72 hours after HIBD.

RESULTSmiRNA-182 that met the criteria was selected by GeneChip and RT-PCR. miRNA-182 was highly expressed in the pineal gland. Compared with the sham-operated group, the expression of miRNA-182 was significantly up-regulated in the pineal gland at 24 and 48 hours after HIBD (P<0.05). Compared with the sham-operated group, Clock mRNA expression in the HIBD group increased at 0 hour after HIBD, decreased at 48 hours after HIBD and increased at 72 hours after HIBD (P<0.05).

CONCLUSIONSmiRNA-182 may be involved in the pathogenesis of circadian rhythm disturbance after HIBD.

Animals ; Animals, Newborn ; CLOCK Proteins ; genetics ; Circadian Rhythm ; physiology ; Female ; Gene Expression Regulation ; Hypoxia-Ischemia, Brain ; physiopathology ; Male ; MicroRNAs ; analysis ; physiology ; Pineal Gland ; metabolism ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Real-Time Polymerase Chain Reaction

Biological rhythms controlled by the circadian clock are absent in embryonic stem cells (ESCs). However, they start to develop during the differentiation of pluripotent ESCs to downstream cells. Conversely, biological rhythms in adult somatic cells disappear when they are reprogrammed into induced pluripotent stem cells (iPSCs). These studies indicated that the development of biological rhythms in ESCs might be closely associated with the maintenance and differentiation of ESCs. The core circadian gene Clock is essential for regulation of biological rhythms. Its role in the development of biological rhythms of ESCs is totally unknown. Here, we used CRISPR/CAS9-mediated genetic editing techniques, to completely knock out the Clock expression in mouse ESCs. By AP, teratoma formation, quantitative real-time PCR and Immunofluorescent staining, we did not find any difference between Clock knockout mESCs and wild type mESCs in morphology and pluripotent capability under the pluripotent state. In brief, these data indicated Clock did not influence the maintaining of pluripotent state. However, they exhibited decreased proliferation and increased apoptosis. Furthermore, the biological rhythms failed to develop in Clock knockout mESCs after spontaneous differentiation, which indicated that there was no compensational factor in most peripheral tissues as described in mice models before (DeBruyne et al., 2007b). After spontaneous differentiation, loss of CLOCK protein due to Clock gene silencing induced spontaneous differentiation of mESCs, indicating an exit from the pluripotent state, or its differentiating ability. Our findings indicate that the core circadian gene Clock may be essential during normal mESCs differentiation by regulating mESCs proliferation, apoptosis and activity.
Animals ; Apoptosis ; Base Sequence ; CLOCK Proteins ; genetics ; metabolism ; CRISPR-Cas Systems ; Cell Differentiation ; Cell Proliferation ; Cellular Reprogramming ; Circadian Clocks ; genetics ; Gene Editing ; Gene Expression Regulation ; Gene Knockout Techniques ; Hepatocyte Nuclear Factor 3-beta ; genetics ; metabolism ; Induced Pluripotent Stem Cells ; cytology ; metabolism ; Mice ; Mouse Embryonic Stem Cells ; cytology ; metabolism ; SOXB1 Transcription Factors ; genetics ; metabolism

By means of a circadian clock system, all the living organisms on earth including human beings can anticipate the environmental rhythmic changes such as light/dark and warm/cold periods in a daily as well as in a yearly manner. Anticipating such environmental changes provide organisms with survival benefits via manifesting behavior and physiology at an advantageous time of the day and year. Cell-autonomous circadian oscillators, governed by transcriptional feedback loop composed of positive and negative elements, are organized into a hierarchical system throughout the organisms and generate an oscillatory expression of a clock gene by itself as well as clock controlled genes (ccgs) with a 24 hr periodicity. In the feedback loop, hetero-dimeric transcription factor complex induces the expression of negative regulatory proteins, which in turn represses the activity of transcription factors to inhibit their own transcription. Thus, for robust oscillatory rhythms of the expression of clock genes as well as ccgs, the precise control of subcellular localization and/or timely translocation of core clock protein are crucial. Here, we discuss how sub-cellular localization and nuclear translocation are controlled in a time-specific manner focusing on the negative regulatory clock proteins.
Circadian Clocks* ; Circadian Rhythm ; CLOCK Proteins ; Humans ; Periodicity ; Phosphorylation ; Physiology ; Protein Processing, Post-Translational ; Repressor Proteins* ; Transcription Factors

OBJECTIVETo investigate the relationship between genetic variantions of circadian clock genes and risk of breast cancer.

METHODSA case-control study including 406 breast cancer patients and 412 controls was conducted and genes Clock (rs2070062) and Per2 (rs2304672, rs2304669, rs934945) were genotyped by TaqMan real-time PCR. Unconditional logistic regression model was used to analyze the association between the genetic polymorphisms and breast cancer.

RESULTSIndividuals with the rs2304669-TT genotype showed significantly increased breast cancer risk with the OR of 2.33 when compared with the individuals with rs2304669-CC and CT genotypes (P = 0.001). In addition, the three haplotypes containing the risk T allele of rs2304669 were identified to be associated with increased breast cancer risk. However, it was found that rs2304672, rs2070062 and rs934945 polymorphisms were not related with breast cancer risk.

CONCLUSIONSThe locus rs2304669 on Per2 gene is associated with breast cancer risk. Genetic variation of circadian clock genes may increase the susceptibility to breast cancer. Therefore, it may become an important biomarker of susceptibility to breast cancer.

Adult ; Biomarkers, Tumor ; genetics ; Breast Neoplasms ; genetics ; CLOCK Proteins ; genetics ; Carcinoma, Ductal, Breast ; genetics ; Case-Control Studies ; Female ; Genetic Variation ; Humans ; Period Circadian Proteins ; genetics ; Polymorphism, Single Nucleotide ; Risk Factors

OBJECTIVETo study the effects of biological clock protein on circadian disorders in hypoxic-ischemic brain damage (HIBD) by examining levels of CLOCK and BMAL1 proteins in the pineal gland of neonatal rats.

METHODSSeventy-two 7-day-old Sprague-Dawley (SD) rats were randomly divided into sham-operated and HIBD groups. HIBD model was prepared according to the modified Levine method. Western blot analysis was used to measure the levels of CLOCK and BMAL1 in the pineal gland at 0, 2, 12, 24, 36 and 48 hours after operation.

RESULTSBoth CLOCK and BMAL levels in the pineal gland increased significantly 48 hours after HIBD compared with the sham-operated group (P<0.05). There were no significant differences in levels of CLOCK and BMAL proteins between the two groups at 0, 2, 12, 24 and 36 hours after operation (P>0.05).

CONCLUSIONSLevels of CLOCK and BMAL1 proteins in the pineal gland of rats increase significantly 48 hours after HIBD, suggesting that both CLOCK and BMAL1 may be involved the regulatory mechanism of circadian disorders in rats with HIBD.

ARNTL Transcription Factors ; analysis ; physiology ; Animals ; Animals, Newborn ; CLOCK Proteins ; analysis ; physiology ; Chronobiology Disorders ; etiology ; Female ; Hypoxia-Ischemia, Brain ; metabolism ; Male ; Pineal Gland ; chemistry ; Rats ; Rats, Sprague-Dawley ; Time Factors

This study investigated the effects of benazepril administered in the morning or evening on the diurnal variation of renin-angiotensin-aldosterone system (RAAS) and clock genes in the kidney. The male Wistar rat models of 5/6 subtotal nephrectomy (STNx) were established. Animals were randomly divided into 4 groups: sham STNx group (control), STNx group, morning benazepril group (MB) and evening benazepril group (EB). Benazepril was intragastrically administered at a dose of 10 mg/kg/day at 07:00 and 19:00 in the MB group and EB group respectively for 12 weeks. All the animals were synchronized to the light:dark cycle of 12:12 for 12 weeks. Systolic blood pressure (SBP), 24-h urinary protein excretion and renal function were measured at 11 weeks. Blood samples and kidneys were collected every 4 h throughout a day to detect the expression pattern of renin activity (RA), angiotensin II (AngII) and aldosterone (Ald) by radioimmunoassay (RIA) and the mRNA expression profile of clock genes (bmal1, dbp and per2) by real-time PCR at 12 weeks. Our results showed that no significant differences were noted in the SBP, 24-h urine protein excretion and renal function between the MB and EB groups. There were no significant differences in average Ald and RA content of a day between the MB group and EB group. The expression peak of bmal1 mRNA was phase-delayed by 4 to 8 h, and the diurnal variation of per2 and dbp mRNA diminished in the MB and EB groups compared with the control and STNx groups. It was concluded when the similar SBP reduction, RAAS inhibition and clock gene profile were achieved with optimal dose of benazepril, morning versus evening dosing of benazepril has the same renoprotection effects.
Animals ; Antihypertensive Agents ; administration & dosage ; Benzazepines ; administration & dosage ; CLOCK Proteins ; metabolism ; Circadian Rhythm ; Drug Chronotherapy ; Gene Expression Profiling ; Hypertension, Renal ; drug therapy ; physiopathology ; Kidney ; drug effects ; physiopathology ; surgery ; Male ; Nephrectomy ; Rats ; Rats, Wistar ; Renin-Angiotensin System ; drug effects ; Treatment Outcome

OBJECTIVETo explore the changes in the expression of pineal clock genes in rats with chronic cerebral ischemia and evaluate the effect of intervention with Wulongdan, a traditional Chinese medicinal preparation, on these changes.

METHODSMale SD rats were randomly divided into sham-operated group, chronic cerebral ischemia model group, and treatment group. In the latter two groups, chronic cerebral ischemia was induced by permanent ligation of the bilateral carotid arteries, and in the treatment group, Wulongdan was administered intragastrically on a daily basis for 3 weeks after the operation. Real-time quantitative RT-PCR was employed to examine the changes in the pineal expressions of Clock, Bmal1, and Per1 mRNA after the treatment.

RESULTSIn the model group, the expression levels of Clock and Per1 mRNA were significantly lowered compared to those in the sham-operated group (P<0.01, P<0.05), but Bmal1 mRNA expression showed no significant changes (P>0.05). Wulongdan treatment caused a significant increase in pineal lock mRNA expression compared to the model group (P<0.01), and significantly reduced pineal Bmal1 expression as compared to the sham-operated group (P<0.05). No significant difference was found in Per1 mRNA expression between the treatment group and the model group.

CONCLUSIONSThe changes in the expressions of the pineal clock genes in rats with chronic cerebral ischemia suggest the association between chronic cerebral ischemia and sleep disorders. Wulongdan can mitigate sleep disorders caused by chronic cerebral ischemia.

Animals ; Brain Ischemia ; metabolism ; CLOCK Proteins ; genetics ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Male ; Pineal Gland ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley