Peripheral Clock System Abnormalities in Patients With Parkinson’s Disease

Objective: To evaluate the altered expression of peripheral clock genes, circulating melatonin levels, and their correlations with sleep-wake phenotypes including probable rapid eye movement sleep behavior disorder (pRBD) symptoms in a relatively large population of Parkinson’s disease (PD) patients.Methods: We determined the expression profiles of five principal clock genes, BMAL1, CLOCK, CRY1, PER1, and PER2, in the peripheral blood mononuclear cells (PBMCs) of PD patients (n = 326), and healthy controls (HC, n = 314) using quantitative real-time PCR. Melatonin concentration in the plasma of two groups was evaluated by enzyme-linked immunosorbent assay. Then we performed comprehensive association analyses on the PBMCs clock gene expression, plasma melatonin levels and sleep characteristics.Results: Our data showed that the expression levels of BMAL1, CLOCK, CRY1, PER1, and PER2 were significantly decreased in the PBMCs of PD as compared with that of HC (P < 0.05). PD patients had reduced plasma melatonin levels compared with HC (P < 0.0001). pRBD and excessive daytime sleepiness are common in these PD patients and are associated with the expression levels of all five clock genes (r = −0.344∼−0.789, P < 0.01) and melatonin concentration (r = −0.509∼−0.753, P < 0.01). Statistical analyses also revealed that a combination of five clock genes and melatonin could reach a high diagnostic performance (areas under the curves, 97%) for PD comorbid pRBD.Conclusion: This case-control study demonstrates that peripheral BMAL1, CLOCK, CRY1, PER1, PER2, and melatonin levels are altered in PD patients and may serve as endogenous markers for sleep and wakefulness disturbances of PD.

The circadian clock gates Drosophila adult emergence by controlling the timecourse of metamorphosis

The daily rhythm of adult emergence of holometabolous insects is one of the first circadian rhythms to be studied. In these insects, the circadian clock imposes a daily pattern of emergence by allowing or stimulating eclosion during certain windows of time and inhibiting emergence during others, a process that has been described as “gating.” Although the circadian rhythm of insect emergence provided many of the key concepts of chronobiology, little progress has been made in understanding the bases of the gating process itself, although the term “gating” suggests that it is separate from the developmental process of metamorphosis. Here, we follow the progression through the final stages of Drosophila adult development with single-animal resolution and show that the circadian clock imposes a daily rhythmicity to the pattern of emergence by controlling when the insect initiates the final steps of metamorphosis itself. Circadian rhythmicity of emergence depends on the coupling between the central clock located in the brain and a peripheral clock located in the prothoracic gland (PG), an endocrine gland whose only known function is the production of the molting hormone, ecdysone. Here, we show that the clock exerts its action by regulating not the levels of ecdysone but that of its actions mediated by the ecdysone receptor. Our findings may also provide insights for understanding the mechanisms by which the daily rhythms of glucocorticoids are produced in mammals, which result from the coupling between the central clock in the suprachiasmatic nucleus and a peripheral clock located in the suprarenal gland.

Abstract MP141: Role of Cryptochrome in Angiogenesis

Background: Although clock genes generate oscillations in about 10 % of all gene expressions as a 24-hour cycle in the cellular level cooperating with the central clock, little is known about the role of clock genes in angiogenesis. Objective: The aim of this study was to determine if a peripheral clock would modulate angiogenesis in a hind limb ischemia (HLI) model. Methods and Results: First, we surgically induced the HLI model in C57BL/6J (wild type; WT) mice (N=6 for each time point) and checked mRNA expressions of clock genes in a local ischemic tissue by PCR array in the setting of blood perfusion recovery. In vitro study, we next investigated those gene expressions in human umbilical vein endothelial cells (HUVECs) with or without stimulation by growth factors. Those data demonstrated that the peripheral clock genes were modulated in ECs and tissues in the presence of growth factors and tissue ischemia. Then, we examined whether inhibition of clock gene expressions 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 hetero knockout mice of HLI models displayed worse blood perfusion recoveries with deterioration of angiogenesis. As results, compared with control WT mice, Cry1 and Cry2 double knockout mice showed the low capillary density detected by CD31-immunohistochemistry and low tissue blood perfusion demonstrated by laser Doppler perfusion imaging (LDPI) in a HLI. Conclusion: Our data indicated that Cryptochrome as a peripheral clock plays an important role in angiogenesis of the reparative tissue ischemia model.

Role of Non-Coding RNAs in Lung Circadian Clock Related Diseases

Circadian oscillations are regulated at both central and peripheral levels to maintain physiological homeostasis. The central circadian clock consists of a central pacemaker in the suprachiasmatic nucleus that is entrained by light dark cycles and this, in turn, synchronizes the peripheral clock inherent in other organs. Circadian dysregulation has been attributed to dysregulation of peripheral clock and also associated with several diseases. Components of the molecular clock are disrupted in lung diseases like chronic obstructive pulmonary disease (COPD), asthma and IPF. Airway epithelial cells play an important role in temporally organizing magnitude of immune response, DNA damage response and acute airway inflammation. Non-coding RNAs play an important role in regulation of molecular clock and in turn are also regulated by clock components. Dysregulation of these non-coding RNAs have been shown to impact the expression of core clock genes as well as clock output genes in many organs. However, no studies have currently looked at the potential impact of these non-coding RNAs on lung molecular clock. This review focuses on the ways how these non-coding RNAs regulate and in turn are regulated by the lung molecular clock and its potential impact on lung diseases.

Effect of a single bout of exercise on clock gene expression in human leukocyte

Mammals have circadian clocks, which consist of the central clock in the suprachiasmatic nucleus and the peripheral clocks in the peripheral tissues. The effect of exercise on phase of peripheral clocks have been reported in rodents but not in humans. Continuous sampling is necessary to assess the phase of the circadian rhythm of peripheral clock gene expressions. It has been assumed that the expression of the genes in leukocyte may be “an accessible window to the multiorgan transcriptome.” The present study aimed to examine whether exercise affects the level and phase of clock gene expression in human leukocytes. Eleven young men participated in three trials, in which they performed a single bout of exercise at 60% V̇o2max for 1 h beginning either at 0700 (morning exercise) or 1600 (afternoon exercise) or no exercise (control). Blood samples were collected at 0600, 0900, 1200, 1500, 1800, 2100, and 2300 and at 0600 the next morning, to assess diurnal changes of clock gene expression in leukocytes. Brain and muscle ARNT-like protein 1 ( Bmal1) expression level increased after morning and afternoon exercise, and Cryptochrome 1 ( Cry1) expression level increased after morning exercise. Compared with control trial, acrophase of Bmal1 expression tended to be earlier in morning exercise trial and later in afternoon exercise trial. Acrophase of Cry1 expression was earlier in morning exercise trial but not affected by afternoon exercise. Circadian locomotor output cycles kaput ( Clock), Period 1–3 ( Per1–3), and Cry2 expression levels and those acrophases were not affected by exercise. The present results suggest a potential role of a single bout of exercise to modify peripheral clocks in humans. NEW & NOTEWORTHY The present study showed that a single bout of exercise affected peripheral clock gene expression in human leukocytes and the effect of exercise depended on when it was performed. Brain and muscle ARNT-like protein 1 ( Bmal1) expression was increased after exercises performed in the morning and afternoon. Cryptochrome 1 ( Cry1) expression was also increased after the morning exercise. The effect of exercise on acrophase of Bmal1 depended on the time of the exercise: advanced after morning exercise and delayed after afternoon exercise.