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Seminars in Immunopathology Mar 2022The daily oscillations of bi ological and behavioural processes are controlled by the circadian clock circuitry that drives the physiology of the organism and, in... (Review)
Review
The daily oscillations of bi ological and behavioural processes are controlled by the circadian clock circuitry that drives the physiology of the organism and, in particular, the functioning of the immune system in response to infectious agents. Circadian rhythmicity is known to affect both the pharmacokinetics and pharmacodynamics of pharmacological agents and vaccine-elicited immune responses. A better understanding of the role circadian pathways play in the regulation of virus replication will impact our clinical management of these diseases. This review summarises the experimental and clinical evidence on the interplay between different viral pathogens and our biological clocks, emphasising the importance of continuing research on the role played by the biological clock in virus-host organism interaction.
Topics: Circadian Clocks; Circadian Rhythm; Humans; Virus Replication
PubMed: 35192001
DOI: 10.1007/s00281-021-00908-2 -
Biomedicine & Pharmacotherapy =... Jan 2023The circadian clock regulates many key physiological processes such as the sleep-wake cycle, hormone release, cardiovascular health, glucose metabolism and body... (Review)
Review
The circadian clock regulates many key physiological processes such as the sleep-wake cycle, hormone release, cardiovascular health, glucose metabolism and body temperature. Recent evidence has suggested a critical role of the circadian system in controlling bone metabolism. Here we review the connection between bone metabolism and the biological clock, and the roles of these mechanisms in bone loss. We also analyze the regulatory effects of clock-related genes on signaling pathways and transcription factors in osteoblasts and osteoclasts. Additionally, osteocytes and endothelial cells (ECs) regulated by the circadian clock are also discussed in our review. Furthermore, we also summarize the regulation of circadian clock genes by some novel modulators, which provides us with a new insight into a potential strategy to prevent and treat bone diseases such as osteoporosis by targeting circadian genes.
Topics: Circadian Rhythm; Endothelial Cells; Biological Clocks; Transcription Factors; Osteoclasts
PubMed: 36423544
DOI: 10.1016/j.biopha.2022.114019 -
Journal of Plant Research Jan 2018Plants have endogenous biological clocks that allow organisms to anticipate and prepare for daily and seasonal environmental changes and increase their fitness in... (Review)
Review
Plants have endogenous biological clocks that allow organisms to anticipate and prepare for daily and seasonal environmental changes and increase their fitness in changing environments. The circadian clock in plants, as in animals and insects, mainly consists of multiple interlocking transcriptional/translational feedback loops. The circadian clock can be entrained by environmental cues such as light, temperature and nutrient status to synchronize internal biological rhythms with surrounding environments. Output pathways link the circadian oscillator to various physiological, developmental, and reproductive processes for adjusting the timing of these biological processes to an appropriate time of day or a suitable season. Recent genomic studies have demonstrated that polymorphism in circadian clock genes may contribute to local adaptations over a wide range of latitudes in many plant species. In the present review, we summarize the circadian regulation of biological processes throughout the life cycle of plants, and describe the contribution of the circadian clock to local adaptation.
Topics: Adaptation, Biological; Circadian Clocks; Plant Development
PubMed: 29134443
DOI: 10.1007/s10265-017-0991-8 -
Journal of Cardiology May 2011Both the physiological and pathological functions of cardiovascular organs are closely related to circadian rhythm, an endogenously driven 24-h cycle. Heart rate, blood... (Review)
Review
Both the physiological and pathological functions of cardiovascular organs are closely related to circadian rhythm, an endogenously driven 24-h cycle. Heart rate, blood pressure, and endothelial function show diurnal variations within a day. The onset of cardiovascular disorders such as acute coronary syndrome, atrial arrhythmia, and subarachinoid hemorrhage also exhibits diurnal oscillation. Recent progress in studying the functions and molecular mechanisms of the biological clock brought forth the idea that intrinsic circadian rhythms are tightly related to cardiovascular pathology. The center of the biological clock exists in the suprachiasmatic nucleus in the hypothalamus. In addition to this central clock, each organ has its own biological clock system, termed the peripheral clock. Each cardiovascular tissue or cell, including heart and aortic tissue, cardiomyocyte, vascular smooth muscle cell, and vascular endothelial cell also has intrinsic biological rhythm. Until recently, little was known about the roles of peripheral clocks in cardiovascular organs. However, studies using genetically engineered mice revealed their contributions during the process of disease progression. Loss of synchronization between the internal clock and external stimuli can induce cardiovascular organ damage. Discrepancy in the phases between the central and peripheral clocks also seems to contribute to progression of the disorders. Elucidation of the precise roles of biological clocks in cardiovascular organs will provide us with more profound insights into the relevance of the circadian rhythm in cardiac pathology. Moreover, identification of the modalities with which we can manipulate the phase of each peripheral clock will enable us to establish a novel chronotherapeutic approach. This time-of-day based strategy may innovate a new paradigm in the prevention and treatment of cardiovascular disorders.
Topics: Acute Coronary Syndrome; Cardiovascular Diseases; Chronotherapy; Circadian Clocks; Disease Progression; Humans; Hypertension
PubMed: 21441015
DOI: 10.1016/j.jjcc.2011.02.006 -
International Journal of Molecular... Jan 2023The ubiquity of biological rhythms in life implies that it results from selection in the evolutionary process. The origin of the biological clock has two possible... (Review)
Review
The ubiquity of biological rhythms in life implies that it results from selection in the evolutionary process. The origin of the biological clock has two possible hypotheses: the selective pressure hypothesis of the oxidative stress cycle and the light evasion hypothesis. Moreover, the biological clock gives life higher adaptability. Two biological clock mechanisms have been discovered: the negative feedback loop of transcription-translation (TTFL) and the post-translational oscillation mechanism (PTO). The TTFL mechanism is the most classic and relatively conservative circadian clock oscillation mechanism, commonly found in eukaryotes. We have introduced the TTFL mechanism of the classical model organisms. However, the biological clock of prokaryotes is based on the PTO mechanism. The Peroxiredoxin (PRX or PRDX) protein-based PTO mechanism circadian clock widely existing in eukaryotic and prokaryotic life is considered a more conservative oscillation mechanism. The coexistence of the PTO and TTFL mechanisms in eukaryotes prompted us to explain the relationship between the two. Finally, we speculated that there might be a driving force for the evolution of the biological clock. The biological clock may have an evolutionary trend from the PTO mechanism to the TTFL mechanism, resulting from the evolution of organisms adapting to the environment.
Topics: Bacterial Proteins; Circadian Clocks; Circadian Rhythm; Eukaryota; Transcription, Genetic; Protein Biosynthesis
PubMed: 36768725
DOI: 10.3390/ijms24032402 -
Frontiers in Endocrinology 2023Physical activity represents a potent, non-pharmacological intervention delaying the onset of over 40 chronic metabolic and cardiovascular diseases, including type 2... (Review)
Review
Physical activity represents a potent, non-pharmacological intervention delaying the onset of over 40 chronic metabolic and cardiovascular diseases, including type 2 diabetes, coronary heart disease, and reducing all-cause mortality. Acute exercise improves glucose homeostasis, with regular participation in physical activity promoting long-term improvements in insulin sensitivity spanning healthy and disease population groups. At the skeletal muscle level, exercise promotes significant cellular reprogramming of metabolic pathways through the activation of mechano- and metabolic sensors, which coordinate downstream activation of transcription factors, augmenting target gene transcription associated with substrate metabolism and mitochondrial biogenesis. It is well established that frequency, intensity, duration, and modality of exercise play a critical role in the type and magnitude of adaptation; albeit, exercise is increasingly considered a vital lifestyle factor with a critical role in the entrainment of the biological clock. Recent research efforts revealed the time-of-day-dependent impact of exercise on metabolism, adaptation, performance, and subsequent health outcomes. The synchrony between external environmental and behavioural cues with internal molecular circadian clock activity is a crucial regulator of circadian homeostasis in physiology and metabolism, defining distinct metabolic and physiological responses to exercise unique to the time of day. Optimising exercise outcomes following when to exercise would be essential to establishing personalised exercise medicine depending on exercise objectives linked to disease states. We aim to provide an overview of the bimodal impact of exercise timing, i.e. the role of exercise as a time-giver () to improve circadian clock alignment and the underpinning clock control of metabolism and the temporal impact of exercise timing on the metabolic and functional outcomes associated with exercise. We will propose research opportunities that may further our understanding of the metabolic rewiring induced by specific exercise timing.
Topics: Humans; Diabetes Mellitus, Type 2; Homeostasis; Acclimatization; Circadian Clocks; Exercise
PubMed: 36875451
DOI: 10.3389/fendo.2023.987208 -
Medecine Sciences : M/S Dec 2020The biological clock plays an essential role in the control of muscle activity, by dissociating temporally the metabolic functions of skeletal muscle. Exercise capacity... (Review)
Review
The biological clock plays an essential role in the control of muscle activity, by dissociating temporally the metabolic functions of skeletal muscle. Exercise capacity also displays a circadian rhythm. Alterations in biological rhythm, as in shift workers, alter muscle function and are associated with the development of sarcopenia.
Topics: Animals; Circadian Clocks; Circadian Rhythm; Energy Metabolism; Exercise; Glucocorticoids; Humans; Muscle, Skeletal; Regeneration; Sarcopenia
PubMed: 33427629
DOI: 10.1051/medsci/2020262 -
Current Opinion in Neurobiology Oct 2013It has been known since the 1970s that the suprachiasmatic nucleus (SCN) is the brain's main biological clock, and since the 1990s that it uses a genetic clock based on... (Review)
Review
It has been known since the 1970s that the suprachiasmatic nucleus (SCN) is the brain's main biological clock, and since the 1990s that it uses a genetic clock based on transcriptional-translational loops to tell time. However, the recent demonstration that many other cells in the brain and the body also make use of the same genetic clock raises the question of how the SCN synchronizes all of the other clocks to arrive at a coherent circadian profile of physiology and behavior. In this review, we re-examine the evidence that the SCN clock is necessary for bringing order to the body's biological rhythms, and the circuitry of the circadian timing system by which it accomplishes this goal. Finally, we review the evidence that under conditions of restricted food availability, other clocks may be able to take over from the SCN to determine rhythms of behavior and physiology.
Topics: Animals; Brain; Circadian Clocks; Circadian Rhythm; Humans; Suprachiasmatic Nucleus
PubMed: 23706187
DOI: 10.1016/j.conb.2013.04.004 -
Journal of Biochemistry Dec 2003Many tissues in non-mammalian vertebrates contain both photoreceptors and circadian clock systems. Among these photosensitive clock structures, the chick pineal gland... (Review)
Review
Many tissues in non-mammalian vertebrates contain both photoreceptors and circadian clock systems. Among these photosensitive clock structures, the chick pineal gland has been characterized in detail from cellular and molecular aspects of the clock oscillation and entrainment. Analyses of the pineal photic-input pathway revealed a phase-shifting mechanism mediated by activation of G11, one of the Gq-type G-proteins. A major photoreceptive molecule, pinopsin, likely triggers this pathway by transmitting the light signal to the circadian oscillator. In the chick pineal oscillator, the transcription/translation-based autoregulatory feedback loop is composed of positive and negative elements (clock gene products) that are homologous to those identified in mammals. In the molecular cycling, a CACGTG E-box located in the promoter region of the negative element genes plays a central role in the transcriptional regulation. The phase of the molecular cycling is modulated by many regulatory components, among which E4BP4 and extracellular signal-regulated kinase (ERK) are closely associated with the photic entrainment. A light-responsive element was found in the promoter region of the Pinopsin gene, and the element included a CACGTG E-box, suggesting a novel role of the E-box as a point of convergence of light and circadian signals. These observations together point to general and unique features of the chick pineal circadian system among animal clocks.
Topics: Animals; Biological Clocks; CLOCK Proteins; Chickens; Circadian Rhythm; Humans; Pineal Gland; Trans-Activators
PubMed: 14769866
DOI: 10.1093/jb/mvg221 -
Frontiers in Bioscience (Landmark... Sep 2021: Dementia and cognitive loss impact a significant proportion of the global population and present almost insurmountable challenges for treatment since they stem from... (Review)
Review
: Dementia and cognitive loss impact a significant proportion of the global population and present almost insurmountable challenges for treatment since they stem from multifactorial etiologies. Innovative avenues for treatment are highly warranted. : Novel work with biological clock genes that oversee circadian rhythm may meet this critical need by focusing upon the pathways of the mechanistic target of rapamycin (mTOR), the silent mating type information regulation 2 homolog 1 () (SIRT1), mammalian forkhead transcription factors (FoxOs), the growth factor erythropoietin (EPO), and the wingless Wnt pathway. These pathways are complex in nature, intimately associated with autophagy that can maintain circadian rhythm, and have an intricate relationship that can lead to beneficial outcomes that may offer neuroprotection, metabolic homeostasis, and prevention of cognitive loss. However, biological clocks and alterations in circadian rhythm also have the potential to lead to devastating effects involving tumorigenesis in conjunction with pathways involving Wnt that oversee angiogenesis and stem cell proliferation. : Current work with biological clocks and circadian rhythm pathways provide exciting possibilities for the treating dementia and cognitive loss, but also provide powerful arguments to further comprehend the intimate and complex relationship among these pathways to fully potentiate desired clinical outcomes.
Topics: Animals; Biological Clocks; Circadian Clocks; Circadian Rhythm; Dementia; Memory Disorders; TOR Serine-Threonine Kinases
PubMed: 34590471
DOI: 10.52586/4971