Autophagy and circadian rhythms:interactions and clinical implications

Autophagy is a widespread biological process that controls cellular growth,survival,development,and death.Circadian rhythm is a recurring reaction of living organisms and behaviors to variations in surrounding brightness and obscurity.Most of the fundamental physiological processes in mammals,such as the sleep-wake pattern and the rhythm of nutrition and energy metabolism,are governed by circadian rhythms.Research has indicated that autophagy exhibits a specific circadian pattern in both normal and abnormal conditions.Autophagy can modulate circadian rhythms by breaking down proteins that regulate the circadian clock.The potential regulatory connection between the two has been a popular subject of clinical and fundamental research.Understanding the interaction between circadian rhythm and autophagy could potentially lead to the development of novel approaches for disease treatment in the future.The present analysis presented a summary of the molecular processes implicated in the interplay between autophagy and circadian rhythm,as well as the pathological importance of the disrupted regulatory association between these two phenomena.

The Clock gene clone and its circadian rhythms in Pelteobagrus vachelli

The Clock gene,a key molecule in circadian systems,is widely distributed in the animal kingdom. We isolated a 936-bp partial c DNA sequence of the C lock gene( Pva- clock) from the darkbarbel catfish P elteobagrus vachelli that exhibited high identity with C lock genes of other species of fish and animals(65%–88%). The putative domains included a basic helix-loop-helix(b HLH) domain and two period-ARNT-single-minded(PAS) domains,which were also similar to those in other species of fish and animals. P va- Clock was primarily expressed in the brain,and was detected in all of the peripheral tissues sampled. Additionally,the pattern of P va- Clock expression over a 24-h period exhibited a circadian rhythm in the brain,liver and intestine,with the acrophase at zeitgeber time 21:35,23:00,and 23:23,respectively. Our results provide insight into the function of the molecular C lock of P. vachelli.

WNT/β-catenin pathway and circadian rhythms in obsessive-compulsive disorder

The neuropsychiatric disease named obsessive-compulsive disorder is composed by obsessions and/or compulsions.Obsessive-compulsive disorder etiologies are undefined.However,numerous mechanisms in several localizations are implicated.Some studies showed that both glutamate,inflammatory factors and oxidative stress could have main functions in obsessive-compulsive disorder.Glycogen synthase kinase-3β,the major negative controller of the WNT/β-catenin pathway is upregulated in obsessive-compulsive disorder.In obsessive-compulsive disorder,some studies presented the actions of the different circadian clock genes.WNT/β-catenin pathway and circadian clock genes appear to be intricate.Thus,this review focuses on the interaction between circadian clock genes and the WNT/β-catenin pathway in obsessive-compulsive disorder.

Nobiletin protects against metabolic syndrome by enhancing circadian rhythms

OBJECTIVE Dysregulation of circadian rhythms is associated with metabolic dysfunction,yet it is unclear whether enhancing clock function by small molecules can ameliorate metabolic disorders.METHODS We used an unbiased chemical screen in fibroblasts expressing PER2::Luc to identify the Clock amplitude-Enhancing Small Mole⁃cule.In diet-induced obese mice and DB/DB mutant mice,we evaluated the effects of the Clock amplitude-Enhancing small Molecule on metabolic syndrome and locomotor activity.RESULTS We identified Nobiletin(NOB),a natural poly⁃methoxylated flavone,as a Clock amplitude-Enhancing Small Molecule by an unbiased chemical screen.In diet-induced obese mice,NOB strongly improved metabolic syndrome and enhanced locomotor activity in a Clock gene-dependent manner.Moreover,the clock is also required for the beneficial effects of NOB on metabolic disorders in DB/DB mutant mice.Notably,NOB enhanced clock protein levels and reprogramed metabolic gene expressions in the liver.Finally,we revealed retinoid acid receptor-related orphan receptors(RORα/γ)as direct targets of NOB.CONCLUSION Altogether,our results demonstrate that a pharmacological intervention that enhances circadian rhythms by small molecule may be as a novel strategy for combating metabolic disease.

Biomarkers of Aging: Changes in Circadian Rhythms Related to the Modulation of Metabolic Output

Twenty-four hour (circadian) rhythmicity is an important component of biological variability associated with studies relating to biomarkers of aging. Chronobiological testing techniques must be utilized because (1) many variables that are related to the modulation of metabolic output vary dramatically at different times of the day; (2) various experimental variable and treatment groups must be synchronized with environmental cues that control circadian rhythms; and (3) multiple circadian variables may interact together to modulate the rate of aging. The rhythm for physiological factors such as whole animal metabolic output, body temperature, heart rate, urine flow, potassium, etc. were found to be dissociated or altered by the senescence process; behavioral variables such as spontaneous activity, wheel running, feeding and drinking, verbal performance, as well as sleep-wakefulness rhythms, seem to be accurate predictors of biological age. Circadian rhythms for a variety of enzymes of intermediary metabolism which are directly associated with energy metabolism have been well documented. These well-defined rhythms of enzyme activity have also been shown to degenerate with aging. Rhythms tend to lose amplitude as activity falls with age and as a general loss of regulation (especially time of day where maximal activity might be found) of activity across the 24-h span occurs. As with behavioral variables, changes in enzyme rhythms appear to accurately predict aging. Generally speaking, the loss of temporal organization with age, characterized by decreased circadian amplitude, loose internal synchronization, and poor response to external environmental time queues, is associated with poor health states and decreased longevity. Temporal rhythms for whole animal parameters are highly correlated with molecular events, such as regulation of cellular metabolism. DNA repair, and gene expression. Automated data acquisition and process control systems will be required for future Chronobiological studies to develop biomarkers of aging.

Circadian Rhythms of Physiological Functions of the Pregnant Woman and the Fetus and the Biological Solemnity Thereof

The basic rhythms of nature that left their imprint on the existence of all living organism on the Earth, arose under the influence of the Earth’s rotation relative to the Sun, the Moon and other planets and stars of the Universe. This periodicity gave rise to the rhythm that has become essential for their life. Life is a continual chemical process of building up and breaking down of organic substances, which results from the substance exchange between an organism and the environment. This makes it impossible for a living organism to exist without the external environment. Since 1978-1979 we have been carrying out a task-oriented research with the aim to approximate the moment when we are able to answer all these questions. Daily fluctuations of cardiac and motor activity of the fetus have been studied (uninterrupted daily recording of fetal ECG);polysomnography of nocturnal sleep was recorded;daily fluctuations of endocrine system activity in the pregnant were studied. A correlation was made between the functional state of maternal sleep-wakefulness biological rhythm, biological clock of the human fetus and the “light-darkness” cycle of a 24-hour solar day. In the process of the study we have developed an original method of day-to-day analysis of maternal and fetal ECGs. It has been established that a healthy fetus has distinct, diurnal variations of physiological functions. The fetal biorhythms coordinate with the status of the maternal organism being, however, in an opposite phase. The curve of the dynamics of fetal physiological system functioning shows a biphasic nature (one-phase in adults). “Active” and “quiet” (sleep-like) periods have been singled out in the human fetus. No reaction is observed in “quiet” periods. However, the “zero”-type fetal reaction recorded by us within the period from 2 p.m. to 9 p.m. does not indicate unsatisfactory condition of the fetus but rather is suggestive of a definite reduction of functional levels of the fetal physiological systems, which is necessary for vital activity. Although conventionally recognized as an indicator of poor state of the fetus, this type only calls for precise attention when recorded in fetal “active” hours. The present study has been the first in the world’s medicine and biorhythmology to detect and establish the daily rhythms of cardiac and motor activity in the human fetus.

Study on the Mechanism of Shimian Granules (SMG) against Depression via Regulating Circadian Rhythms

Background:According to the World Health Organization,about 350 million people worldwide are suffering from depression.It's reported that depression has been linked to several circadian rhythm perturbations,suggesting a disruption of the circadian clock system in affective disorders.The present study investigates the possible molecular mechanism of Shimian granules(SMG)in treating depression via restoring disrupted circadian rhythms.Method:Firstly,network pharmacology approach was used to identify the compounds and potential targets of SMG in TCMIP and BATMAN-TCM database.Secondly,the differential expression genes were obtained by gene expression profiling in GEO database(GSE56931,GSE98793).Further,protein-protein interactions(PPI)network was used to screen out core targets by STRING v11.Moreover,functional enrichment was carried out in DAVID database.Conclusively,the"herbs-compounds-targets-pathways"network was established to explore the mechanism of SMG in the treatment of depression.Result:It was found out that 65 compounds,18 targets and three pathways contributed to SMG in treating depression by regulating disrupted circadian rhythms,which might relate to core targets TNF,IL10,VDR in cAMP and calcium signaling pathway.Conclusion:Network pharmacology combined with gene expression profiling exhibited a powerful means to investigate the possible mechanism of formula,which contributes to theoretical basis for further study of SMG in the treatment of depression.

Circadian rhythms in the growth and reproduction of the brown alga Undaria pinnatifida and gametogenesis under different photoperiods

Circadian growth rhythm of the juvenile sporophyte of the brown alga Undaria pinnatifida was measured with the computer-aided image analysis system in constant florescent white light under constant temperature （ 10 ℃ ）. The growth rhythm persisted for 4 d in constant light with a free-running period of 25.6 h. Egg release from filamentous gametophytes pre-cultured in the light - dark regime was evaluated for six consecutive days at fixed time intervals in constant white light and 12 h light per day. Egg release rhythm persisted for 3 d in both regimes, indicating the endogenous nature. Temporal scale of egg release and gametogenesis in 18, 16, 12 and 8 h light per day were evaluated respectively using vegetatively propagated filamentous gametophytes. Egg release occurred 2 h after the onset of dark phase and peaked at midnight. Evaluation of the rates of oogonium formation, egg release or fertilization revealed no significant differences in four light-dark regimes, indicating the great plasticity of sexual reproduction. No photoperiodic effect in gametogenesis in terms of oogonium formation and egg release was found, but fertilization in short days was significantly higher than in long days. Results of this investigation further confirmed the general occurrence of circadian rhythms in intertidal seaweed species.

The role of pineal microRNA-325 in regulating circadian rhythms after neonatal hypoxic-ischemic brain damage

Circadian rhythm disorder is a common,but often neglected,consequence of neonatal hypoxic-ischemic brain damage(HIBD).However,the underlying molecular mechanisms remain largely unknown.We previously showed that,in a rat model of HIBD,up-regulation of microRNA-325(miR-325)in the pineal gland is responsible for the suppression of Aanat,a key enzyme involved in melatonin synthesis and circadian rhythm regulation.To better understand the mechanism by which miR-325 affects circadian rhythms in neonates with HIBD,we compared clinical samples from neonates with HIBD and samples from healthy neonates recruited from the First Affiliated Hospital of Soochow University(Dushuhu Branch)in 2019.We found that circulating miR-325 levels correlated positively with the severity of sleep and circadian rhythm disorders in neonates with HIBD.Furthermore,a luciferase reporter gene assay revealed that LIM homeobox 3(LHX3)is a novel downstream target of miR-325.In addition,in miR-325 knock-down mice,the transcription factor LHX3 exhibited an miR-325-dependent circadian pattern of expression in the pineal gland.We established a neonatal mouse model of HIBD by performing doublelayer ligation of the left common carotid artery and exposing the pups to a low-oxygen environment for 2 hours.Lhx3 mRNA expression was significantly down-regulated in these mice and partially rescued in miR-325 knockout mice subjected to the same conditions.Finally,we showed that improvement in circadian rhythm-related behaviors in animals with HIBD was dependent on both miR-325 and LHX3.Taken together,our findings suggest that the miR-325-LHX3 axis is responsible for regulating circadian rhythms and provide novel insights into the identification of potential therapeutic targets for circadian rhythm disorders in patients with neonatal HIBD.The clinical trial was approved by Institutional Review Board of Children’s Hospital of Soochow University(approval No.2015028)on July 20,2015.Animal experiments were approved by Animal Care and Use Committee,School of Medicine,Soochow University,China(approval No.XD-2016-1)on January 15,2016.

Effects of Exposure to Extremely Low Frequency Electro-magnetic Fields on Circadian Rhythms and Distribution of Some Leukocyte Differentiation Antigens in Dairy Cows

Objective To investigate the effects of extremely low frequency magnetic and electric fields （ELFEMFs） emitted from 380 kV transmission lines on some leukocyte differentiation antigens in dairy cows. Methods The study was carded out in 5 cows exposed to 1.98-3.28 μT of ELFEMFs and in 5 control cows exposed to 0.2-0.7 μT of ELFEMFs. Following haematological and immunologic parameters were measured in both groups： WBC, CD45R, CD6, CD4, CD8, CD21, and CD11B leukocyte antigen expression. Results Some of the haematological and immunologic parameters under investigation were similar in both groups. However, CD8 （T lymphocyte surface antigen） was higher in the exposed group （1.35 ±0.120 vs 0.50 ±0.14×10^3/mL）. Furthermore, the CD4/CD8 ratio （0.84 ±0.05 and 2.19±0.16 for exposed and not exposed cows respectively） and circadian rhythm were different between the two groups. Conclusion Exposure to ELFEMFs is responsible of the abnormal temporal variations and distribution of some haematological and immunological parameters in dairy cows.

Effects of Different Electromagnetic Fields on Circadian Rhythms of Some Haematochemical Parameters in Rats

Objective To investigate the effects of different electromagnetic fields on some haematochemical parameters of circadian rhythms in Sprague-Dawley rats. Methods The study was carried out in 18 male and 18 female rats in good health conditions exposed to 50 Hz magnetic sinusoid fields at the intensity of 1000 μT, 100 μT, and 0 μT （control group） respectively, and in 18 male and 18 female rats in good health conditions exposed to 1.8 GHz electromagnetic fields at the intensity of 50 V/m, 25 V/m and 0 V/m （control group）, respectively. Following haematochemical parameters for glucose, triglycerides, and total cholesterol were measured. Results Different effects of electromagnetic fields on circadian rhythms of both male and female rats were observed. Different changes occurred in some haematochemical parameters for glucose, triglycerides, and total cholesterol （P〈0.05）. Conclusion Exposure to different electromagnetic fields is responsible for the variations of some haematochemical parameters in rats.

Corneal and intraocular pressure changes associated to the circadian rhythms:a narrative review

AIM:To synthesize the current body of research regarding the diurnal variations in intraocular pressure(IOP)and corneal biomechanical and morphological parameters,highlighting their significance in various eye conditions.METHODS:A comprehensive review of studies on the diurnal variations of IOP and corneal parameters was conducted.Tonometry findings from various studies were assessed,including the Goldmann applanation tonometry(GAT)and non-contact tonometers.Data on the variations in central corneal thickness(CCT),corneal curvature,and corneal biomechanics measured by the Ocular Response Analyzer system across different population groups was extracted and analyzed.RESULTS:In both healthy subjects and those with Fuchs dystrophy,IOP and CCT demonstrate marked diurnal declines.GAT remains the gold standard for tonometry,with the highest reliability.However,its measurements are influenced by CCT.Keratoconus patients and those with pseudoexfoliation showed significant diurnal variations in IOP.The biomechanical parameters,especially corneal hysteresis(CH)and the corneal resistance factor(CRF),largely remain stable throughout the day for most of eye conditions,with some exceptions.Notably,the corneal morphology diurnal variation,particularly curvature,yielded mixed conclusions across studies.CONCLUSION:Circadian rhythms significantly influence various corneal parameters,most notably IOP and CCT.Further studies should emphasize standardized approaches larger sample sizes,and delve deeper into less-explored areas,such as the effects of orthokeratology lenses on diurnal biomechanical shifts.

Targeting the blood-brain barrier to delay aging-accompanied neurological diseases by modulating gut microbiota,circadian rhythms,and their interplays

AbstracTthe blood-brain barrier(BBB)impairment plays a crucial role in the pathological processes of aging-accompanied neurological diseases(AAND).Meanwhile,circadian rhythms disruption and gut microbiota dysbiosis are associated with increased morbidity of neurological diseases in the accelerated aging population.Importantly,circadian rhythms disruption and gut microbiota dysbiosis are also known to induce the generation of toxic metabolites and pro-inflammatory cytokines,resulting in disruption of BBB integrity.Collectively,this provides a new perspective for exploring the relationship among circadian rhythms,gut microbes,and the BBB in aging-accompanied neurological diseases.In this review,we focus on recent advances in the interplay between circadian rhythm disturbances and gut microbiota dysbiosis,and their potential roles in the BBB disruption that occurs in AAND.Based on existing literature,we discuss and propose potential mechanisms underlying BBB damage induced by dysregulated circadian rhythms and gut microbiota,which would serve as the basis for developing potential interventions to protect the BBB in the aging population through targeting the BBB by exploiting its links with gut microbiota and circadian rhythms for treating AAND.

Regulation of circadian physiology and behavior by light in mammals:entrainment and masking

manifestation of circadian rhythms.The modern use of electric lights alters environmental lighting,leading to light exposure at inappropriate times to disturb circadian homeostasis for both human and wildlife.The light“pollution”and voluntary activities such as night shift work and transmeridian travelling have adverse consequences such as mood and metabolic disorders in humans.On the other hand,insufficient light exposure decreases neurotransmission from the locus ceruleus and dorsal raphe,leading to seasonal and nonseasonal affective disorders,while properly timed bright light is beneficial to mood and cognition.Given the critical and complex roles of light in mammalian physiology and behavior,it is essential to understand the underlying mechanisms.In this review,we discuss the neural mechanisms through which light regulates and dysregulates circadian rhythms in mammals.

Irisin/BDNF signaling in the muscle-brain axis and circadian system: A review

In mammals,the timing of physiological,biochemical and behavioral processes over a 24-h period is controlled by circadian rhythms.To entrain the master clock located in the suprachiasmatic nucleus of the hypothalamus to a precise 24-h rhythm,environmental zeitgebers are used by the circadian system.This is done primarily by signals from the retina via the retinohypothalamic tract,but other cues like exercise,feeding,temperature,anxiety,and social events have also been shown to act as non-photic zeitgebers.The recently identified myokine irisin is proposed to serve as an entraining non-photic signal of exercise.Irisin is a product of cleavage and modification from its precursor membrane fibronectin typeⅢdomain-containing protein 5(FNDC5)in response to exercise.Apart from well-known peripheral effects,such as inducing the"browning"of white adipocytes,irisin can penetrate the blood-brain barrier and display the effects on the brain.Experimental data suggest that FNDC5/irisin mediates the positive effects of physical activity on brain functions.In several brain areas,irisin induces the production of brain-derived neurotrophic factor(BDNF).In the master clock,a significant role in gating photic stimuli in the retinohypothalamic synapse for BDNF is suggested.However,the brain receptor for irisin remains unknown.In the current review,the interactions of physical activity and the irisin/BDNF axis with the circadian system are reconceptualized.

Circadian rhythms and inflammatory diseases of the liver and gut

Circadian rhythms play a central role in maintaining metabolic homeostasis and orchestrating interorgan crosstalk.Research evidence indicates that disruption to rhythms,which occurs through shift work,chronic sleep disruption,molecular clock polymorphisms,or the consumption of alcohol or highfat diets,can influence inflammatory status and disrupt timing between the brain and periphery or between the body and the external environment.Within the liver and gut,circadian rhythms direct the timing of glucose and lipid homeostasis,bile acid and xenobiotic metabolism,and nutrient absorption,making these systems particularly susceptible to the effects of disrupted rhythms.In this review,the impacts of circadian disruption will be discussed with emphasis on inflammatory conditions affecting the liver and gut,and the potential for chronotherapy for these conditions will be explored.

CRISPR/Cas9-mediated knockout of period reveals its function in the circadian rhythms of the diamondback moth Plutella xylostella

Circadian clocks control the rhythmicity of many behaviors and physiological features of insects.To study the circadian clock of the moth Plutella xylostella,we employed CRISPR/Cas9-mediated genome editing to investigate the effect of loss of the clock gene period on the circadian rhythms.P.xylostella harbors a single copy of period.Phylogenetic analysis showed that P.xylostella PERIOD is more homologous to mouse PERIOD than the PERIOD proteins from bees,flies,mosquitos,and many other Lepidoptera,such as Danaus plexippus and Bombyx mori.The circadian rhythms in adult locomotor activity were altered in the period knockout strain of P.xylostella under light–dark(LD)and continuous dark(DD)conditions.Under the LD cycle,the wild-type moths displayed nocturnal activity with activity peaking very early after lights off and quickly declining after lights on.In contrast,the period knockout strain had no peak in activity when the lights were turned off and exhibited steady activity throughout the hours of darkness.Interestingly,under DD conditions,our results showed that the locomotor rhythm can be maintained without period gene,but at a lower rhythmicity ratio than wild-type.In addition,knockout of period in P.xylostella changed circadian rhythms patterns related to pupal eclosion,mating,egg-laying,and egg hatching.Mechanistically,loss of PERIOD disrupted the molecular rhythm of period and changed the clock transcription rhythm in the heads of the moths under LD and DD conditions.Together,our study indicates that the PERIOD is required for normal expression of many behavioral rhythms in P.xylostella.

Circadian rhythm disruption and retinal dysfunction:a bidirectional link in Alzheimer’s disease?

Dysfunction in circadian rhythms is a common occurrence in patients with Alzheimer’s disease.A predominant function of the retina is circadian synchronization,carrying information to the brain through the retinohypothalamic tract,which projects to the suprachiasmatic nucleus.Notably,Alzheimer’s disease hallmarks,including amyloid-β,are present in the retinas of Alzheimer’s disease patients,followed/associated by structural and functional disturbances.However,the mechanistic link between circadian dysfunction and the pathological changes affecting the retina in Alzheimer’s disease is not fully understood,although some studies point to the possibility that retinal dysfunction could be considered an early pathological process that directly modulates the circadian rhythm.

The Regulatory Role and Mechanism of Circadian Rhythm in Hemoglobin Co-cultured Neurovascular Unit

Objective Intracranial hemorrhage(ICH),the second most common subtype of stroke,exacerbates the disruption of the blood-brain barrier(BBB),leading to vasogenic edema,plasma protein extravasation,and infiltration of neurotoxic substances.The clearance capacity of the brain plays a crucial role in maintaining BBB homeostasis and facilitating patient recovery after hemorrhage.This study aimed to investigate the effect of circadian rhythms on BBB function,neuronal damage,and clearance capabilities.Methods The transwell model and hemoglobin were co-cultured to simulate the BBB environment after ICH.After intervention with different light groups,neuronal apoptosis was determined,glial phagocytosis was analyzed,the expression of endogenous clearing-related proteins aquaporin 4(AQP4)and low-density lipoprotein receptor-related protein 1(LRP1)was detected by western blotting and immunofluorescence dual standard method,and the expression of the tight junction protein occludin and melatonin receptor 1A(MTNR1A)was quantitatively analyzed.Results Circadian rhythms play a key role in maintaining the integrity of the BBB,reducing oxidative stress-induced neuronal damage,and improving microglial phagocytosis.Meanwhile,the expression of occludin and MTNR1A in neurovascular unit(NVU)co-cultured with hemoglobin improved the expression of AQP4 and LRP1,the key proteins in the NVU's endogenous brain clearance system.Conclusion Circadian rhythm(alternating black and white light)protects the NVU BBB function after ICH,promotes the expression of proteins related to the clearance of the hematoma,provides new evidence for the clinical treatment of patients recovering from ICH,and improves the circadian rhythm to promote brain metabolism and hematoma clearance.

Probiotics administration alleviates cognitive impairment and circadian rhythm disturbance induced by sleep deprivation

Gut microbiome is indispensable for maintaining normal brain function.Specifically,gut microbiota plays a causal role in sleep deprivation(SD)-induced cognitive impairment.In this study,neurobehavioral effects of the Bifidobacterium breve strain(CCFM1025)were assessed in sleep-deprived mice.CCFM1025 improved the body weight and food and water intake of the mice.It also alleviated SD-induced cognitive behavioural abnormalities(in the novel object recognition test),but did not show beneficial effects on mood-and spatial memory-related behaviours.CCFM1025 significantly altered the gut microbial composition and genome function.Key microbial metabolites that may regulate sleep function were also identified,such as isovaleric acid andγ-aminobutyric acid in the gut and purine metabolites in the serum.Those metabolites may participate in gutbrain communication by acting on the striatal melatonin system,for example to increase melatonin levels,and by regulating the expression of circadian clock genes such as those encoding the adenosine A2A receptor and period circadian regulator 1.Collectively,administration of probiotics alleviated cognitive impairment and circadian rhythm disturbance induced by SD via modulation of gut microbiome and its metabolites.These findings may help guide the treatment of insomnia or other sleep disorders via dietary strategies.