Circadian integration of metabolism and energetics

Aminooxyacetic acid up-regulates the Cry1 and Bmal1 clock gene in a sirtuin 1 dependent manner. In vitro study

The regulation of the cyclic oscillation of the components of the circadian clock is complex in itself. Numerous clock interactions with processes and molecules present in cells further complicate this mechanism. Recently, the anti-aging protein Silencing Information Regulator Two family member, SIRT1, has been linked with the molecular circadian clock. In this study, we investigated the in vitro effect of aminooxyacetic acid on SIRT1 expression in relation to circadian dynamics of Cry1 and Bma11 expressions in serum shocked NIH-3 T3 and HaCaT cells. The study was carried out in the context of the inhibitory activity of aminooxyacetic acid against cystathionine-β-synthase and cystathionine-γ-lyase. We have shown that aminooxyacetic acid effectively inhibits SIRT1 transcription and synthesis, which, given the pleiotropic effects of sirtuin 1 on numerous metabolic pathways, may have other implications. We also found that AOAA contributes to up-regulation of the expression of the Cry1 and Bmal1 genes in cells. This effect does not appear to be related to inhibition of the activity of cystathionine-β-synthase and cystathionine-γ-lyase. At the same time, this does not deny the role of hydrogen sulphide, a product of the activity of these enzymes, in the regulation of the circadian clock.

Astrocytes at the heart of sleep: from genes to network dynamics

Astrocytes have transcended their role from mere structural scaffolds to pivotal regulators of neural circuitry and sleep-wake dynamics. The strategic proximity of their fine processes to blood vessels and synapses positions them as key players in neurobiology, contributing to the tripartite synapse concept. Gap-junction proteins also enable astrocytes to form an extensive network interacting with neuronal assemblies to influence sleep physiology. Recent advances in genetic engineering, neuroimaging and molecular biology have deepened our understanding of astrocytic functions. This review highlights the different mechanisms by which astrocytes regulate sleep, notably through transcriptomic and morphological changes, as well as gliotransmission, whereby intracellular calcium (Ca2+) dynamics plays a significant role in modulating the sleep-wake cycle. In vivo optogenetic stimulation of astrocytes indeed induces ATP release, which is subsequently degraded into adenosine, modulating neuronal excitability in sleep-wake regulatory brain regions. Astrocytes also participate in synaptic plasticity, potentially modulating sleep-associated downscaling, a process essential for memory consolidation and preventing synaptic saturation. Although astrocytic involvement in synaptic maintenance is well supported, the precise molecular mechanisms linking these processes to sleep regulation remain to be elucidated. By highlighting astrocytes' multiple roles in sleep physiology, these insights deepen our understanding of sleep mechanisms and pave the way for improving sleep quality.

The Pro-Apoptotic Effect of Glucose Restriction in NSCLC via AMPK-Regulated Circadian Clock Gene Bmal1

The circadian clock is a crucial regulator of mammalian physiology, controlling daily oscillations in key biological processes, such as cell proliferation, apoptosis, and DNA damage repair. Disruption of circadian rhythms has been identified as a significant risk factor for cancer development and progression, yet the specific molecular mechanisms linking circadian dysfunction to cancer remain poorly understood. Recent studies have increasingly focused on the role of diet in modulating circadian rhythms, highlighting the potential for dietary interventions in cancer management. However, how dietary factors like glucose restriction interact with circadian rhythms to influence cancer cell behavior remains an open question. Here, we investigate the mechanisms underlying glucose restriction-induced apoptosis in non-small cell lung cancer (NSCLC) cells, with a focus on the role of circadian clock genes. Analysis of the GEPIA database revealed that the circadian gene Bmal1 is highly expressed in normal tissues and associated with better prognosis in lung adenocarcinoma patients. In NSCLC cells, Bmal1 expression correlated with proapoptotic gene activity. In a tumor xenograft model using severe combined immunodeficiency (SCID) mice, a glucose-restricted (ketogenic) diet significantly delayed tumor growth and increased the expression of Bmal1 and proapoptotic genes. These findings suggest that glucose restriction promotes apoptosis in NSCLC cells through a Bmal1-mediated pathway, providing novel insights into the intersection between circadian regulation and cancer biology. Targeting core circadian clock genes like Bmal1 may represent a promising therapeutic strategy for managing lung cancer, broadening our understanding of how circadian rhythms can be harnessed for cancer prevention and treatment.

Circadian clock-independent ultradian rhythms in lipid metabolism in the Drosophila fat body

The role of circadian clocks in regulating metabolic processes is well known; however, their impact on metabolic states across species and life stages remains largely unexplored. This study investigates the relationship between circadian rhythms and metabolic regulation in the Drosophila larval fat body, a metabolic hub analogous to the mammalian liver and adipose tissue. Surprisingly, the fat body of period null mutants, which lack a functional circadian clock in all tissues, exhibited 12-hour rhythms in gene expression, particularly those involved in peroxisome function, lipid metabolism, and oxidative stress response. These transcriptomic rhythms were aligned with 12-hour oscillations in peroxisome biogenesis and activity, reactive oxygen species levels, and lipid peroxidation. Furthermore, period mutants exhibited 12-hour rhythms in body fat storage, ultimately leading to a net reduction in body fat levels. Collectively, our results identify clock-independent ultradian rhythms in lipid metabolism that are essential for larval survival and development.

Conundrum and chances of diabetes management in the Western Pacific Region: A narrative review

The prevalence of diabetes is increasing globally, and glucose management is essential for the treatment of diabetes. Most guidelines recommend early intensive therapy and individualized approaches. Although many countries have implemented various guidelines and educational programs to enhance glucose management, the target achievement rate still remains very low. Studies from several countries and regions have identified various factors that influence blood glucose management, either positively or negatively. These factors have been comprehensively incorporated into guidelines to assist people with diabetes and healthcare professionals in following them and/or developing additional guidelines through further research. We and others have suggested that diverse factors should be considered-including comorbidities, age, complications, life expectancy, and pathophysiologic characteristics, such as ethnic differences in insulin sensitivity and secretion. The Western Pacific (WP) region, comprising countries with significant cultural and racial diversity, necessitates customized programs and community-based management strategies. In this review, we present specific challenges and opportunities for diabetes management identified through a systematic review of the literature from the WP region, along with those common to other regions. To improve healthcare policy and management in the WP region, it is essential to address regional characteristics and the factors that act as either barriers or facilitators to develop strategies for early intensive and individualized therapeutic approaches. Moreover, additional studies on diabetes pathophysiology and management-including pharmacotherapy-are urgently needed.

Exploring the nexus: Sleep disorders, circadian dysregulation, and Alzheimer's disease

We reviewed the connections among Alzheimer's disease (AD), sleep deprivation, and circadian rhythm disorders. Evidence is mounting that disrupted sleep and abnormal circadian rhythms are not merely symptoms of AD, but are also involved in accelerating the disease. Amyloid-beta (Aβ) accumulates, a feature of AD, and worsens with sleep deprivation because glymphatic withdrawal is required to clear toxic proteins from the brain. In addition, disturbances in circadian rhythm can contribute to the induction of neuroinflammation and oxidative stress, thereby accelerating neurodegenerative processes. While these interactions are bidirectional, Alzheimer's pathology further disrupts sleep and circadian function in a vicious cycle that worsens cognitive decline, which is emphasized in the review. The evidence that targeting sleep and circadian mechanisms may serve as therapeutic strategies for AD was strengthened by this study through the analysis of the molecular and physiological pathways. Further work on this nexus could help unravel the neurobiological mechanisms common to the onset of Alzheimer's and disrupted sleep and circadian regulation, which could result in earlier intervention to slow or prevent the onset of the disease.

Single-cell and bulk transcriptome sequencing identifies circadian rhythm disruption and cluster-specific clinical insights in colorectal tumorigenesis

BACKGROUND

Colorectal cancer (CRC) is one of the most common malignant tumors in the digestive system worldwide, with its mortality ranking second among all cancers. Studies have indicated that disruptions in circadian rhythm (CR) are associated with the occurrence of various cancers; however, the relationship between CR and CRC requires further evidence, and research on the application of CR in CRC is still limited.

METHODS

In this study, we employed both bulk and single-cell RNA sequencing to explore the dysregulation of CR in patients with CRC. By constructing a CR subtype classifier, we conducted an in-depth analysis of the prognostic significance, the status of the tumor microenvironment, and response to immune checkpoint blockade (ICB) therapy between different CR clusters. Furthermore, we developed a CR scoring system (CRS) using machine learning to predict overall survival and identified several genes as potential targets affecting CRC prognosis.

RESULTS

Our findings revealed significant alterations in CR genes and status between CRC and normal tissues using bulk and single-cell transcriptome sequencing. Patients with CRC could be categorized into two distinct CR clusters (CR cluster 1 and 2). The prognosis of CR cluster 2, with higher epithelial-mesenchymal transition (EMT) and angiogenesis scores, was significantly worser than that of CR cluster 1. These clusters exhibited distinct levels of tumor-infiltrating lymphocytes. CR cluster 2 with a notably higher proportion of patients with microsatellite-instability-high (MSI-H), potentially benefit from ICB therapy. The proportion of patients belonging to consensus molecular subtype 4 (CMS4) in CR cluster 2 was also notably higher than in CR cluster 1. Additionally, the CRS combined with tumor stage demonstrated superior overall survival prediction efficacy compared to traditional tumor stage. We revealed a potential link between model genes (LSAMP, MS4A2, NAV3, RAB3B, SIX4) and the disruption of CR and patient prognosis.

CONCLUSION

This study not only provide new insights into the assessment of CR status in CRC patients but also develop a prognosis model based on CR-related genes, offering a new tool for personalized risk assessment in CRC.

Advancing Chrononutrition for Cardiometabolic Health: A 2023 National Heart, Lung, and Blood Institute Workshop Report

The circadian system maintains optimal biological functions at the appropriate time of day, and the disruption of this organization can contribute to the pathogenesis of cardiometabolic disorders. The timing of eating is a prominent external time cue that influences the circadian system. "Chrononutrition" is an emerging dimension of nutrition and active area of research that examines how timing-related aspects of eating and nutrition impact circadian rhythms, biological processes, and disease pathogenesis. There is evidence to support chrononutrition as a form of chronotherapy, such that optimizing the timing of eating may serve as an actionable strategy to improve cardiometabolic health. This report summarizes key information from the National Heart, Lung, and Blood Institute's virtual workshop entitled "Chrononutrition: Elucidating the Role of Circadian Biology and Meal Timing in Cardiometabolic Health," which convened on May 2 to 3, 2023, to review current literature and identify critical knowledge gaps and research opportunities. The speakers presented evidence highlighting the impact on cardiometabolic health of earlier and shorter eating windows and more consistent day-to-day eating patterns. The multidimensionality of chrononutrition was a common theme, as it encompasses multiple facets of eating along with the timing of other behaviors including sleep and physical activity. Advancing the emerging field of chrononutrition will require: (1) standardization of terminology and metrics; (2) scalable and precise tools for real-world settings; (3) consideration of individual differences that may act as effect modifiers; and (4) deeper understanding of social, behavioral, and cultural influences. Ultimately, there is great potential for circadian-based dietary interventions to improve cardiometabolic health.

Lactate induces oxidative stress by HIF1α stabilization and circadian clock disturbance in mammary gland of dairy cows

BACKGROUND

Lactate is a classical byproduct of glucose metabolism, and the main lactate production pathway depends on glycolysis. Lactate stabilized HIF1α by inhibiting PHD activity, leading to hypoxic stress response and exacerbating glycolysis in multiple tissues. However, the redox induction mechanism of lactate in mammary gland has not been understood yet. Herein, we describe a lactate-responsive HIF1α/circadian control mechanism in oxidative stress in the mammary glands of dairy cows.

RESULTS

The in vivo study showed that dairy cows with high lactate concentrations are associated with reduced milk yield and more ROS accumulation in mammary gland. Western blot results in MAC-T cells showed positive correlation between lactate concentrations, expression of HIF1α and oxidative stress indicators, but not circadian core components. To test how lactate-mediated HIF1α dysfunction leads to cell protection process, we investigated altered expression of circadian core related genes following HIF1α stabilization. We found that stabilized HIF1α by lactate inhibited stimulated expression of circadian core components due to the similarity of HRE and E-box transcription elements. Furthermore, we found that lactate treatment strengthened the binding of HIF1α with BMAL1, HMOX1 and FOXO3 in MAC-T cells. Moreover, HIF1α knockdown altered expression of circadian rhythm related genes and reduced oxidative stress state.

CONCLUSION

In summary, our study highlights the central role of competitive transcriptional element occupancy in lactate-mediated oxidative stress of mammary gland, which is caused by HIF1α stabilization and circadian rhythm dysfunction. Our findings introduce a novel nutritional strategy with potential applications in dairy farming for optimizing milk production and maintaining mammary gland health.

Decoding the nexus: branched-chain amino acids and their connection with sleep, circadian rhythms, and cardiometabolic health

The sleep-wake cycle stands as an integrative process essential for sustaining optimal brain function and, either directly or indirectly, overall body health, encompassing metabolic and cardiovascular well-being. Given the heightened metabolic activity of the brain, there exists a considerable demand for nutrients in comparison to other organs. Among these, the branched-chain amino acids, comprising leucine, isoleucine, and valine, display distinctive significance, from their contribution to protein structure to their involvement in overall metabolism, especially in cerebral processes. Among the first amino acids that are released into circulation post-food intake, branched-chain amino acids assume a pivotal role in the regulation of protein synthesis, modulating insulin secretion and the amino acid sensing pathway of target of rapamycin. Branched-chain amino acids are key players in influencing the brain's uptake of monoamine precursors, competing for a shared transporter. Beyond their involvement in protein synthesis, these amino acids contribute to the metabolic cycles of γ-aminobutyric acid and glutamate, as well as energy metabolism. Notably, they impact GABAergic neurons and the excitation/inhibition balance. The rhythmicity of branched-chain amino acids in plasma concentrations, observed over a 24-hour cycle and conserved in rodent models, is under circadian clock control. The mechanisms underlying those rhythms and the physiological consequences of their disruption are not fully understood. Disturbed sleep, obesity, diabetes, and cardiovascular diseases can elevate branched-chain amino acid concentrations or modify their oscillatory dynamics. The mechanisms driving these effects are currently the focal point of ongoing research efforts, since normalizing branched-chain amino acid levels has the ability to alleviate the severity of these pathologies. In this context, the Drosophila model, though underutilized, holds promise in shedding new light on these mechanisms. Initial findings indicate its potential to introduce novel concepts, particularly in elucidating the intricate connections between the circadian clock, sleep/wake, and metabolism. Consequently, the use and transport of branched-chain amino acids emerge as critical components and orchestrators in the web of interactions across multiple organs throughout the sleep/wake cycle. They could represent one of the so far elusive mechanisms connecting sleep patterns to metabolic and cardiovascular health, paving the way for potential therapeutic interventions.

Pharmacological targeting of BMAL1 modulates circadian and immune pathways

The basic helix-loop-helix PER-ARNT-SIM (bHLH-PAS) proteins BMAL1 and CLOCK heterodimerize to form the master transcription factor governing rhythmic gene expression. Owing to connections between circadian regulation and numerous physiological pathways, targeting the BMAL1-CLOCK complex pharmacologically is an attractive entry point for intervening in circadian-related processes. In this study, we developed a small molecule, Core Circadian Modulator (CCM), that targets the cavity in the PASB domain of BMAL1, causing it to expand, leading to conformational changes in the PASB domain and altering the functions of BMAL1 as a transcription factor. Biochemical, structural and cellular investigations validate the high level of selectivity of CCM in engaging BMAL1, enabling direct access to BMAL1-CLOCK cellular activities. CCM induces dose-dependent alterations in PER2-Luc oscillations and orchestrates the downregulation of inflammatory and phagocytic pathways in macrophages. These findings collectively reveal that the BMAL1 protein architecture is inherently configured to enable the binding of chemical ligands for functional modulation.

Disruption of circadian rhythm as a potential pathogenesis of nocturia

Increasing evidence suggested the multifactorial nature of nocturia, but the true pathogenesis of this condition still remains to be elucidated. Contemporary clinical medications are mostly symptom based, aimed at either reducing nocturnal urine volume or targeting autonomic receptors within the bladder to facilitate urine storage. The day-night switch of the micturition pattern is controlled by circadian clocks located both in the central nervous system and in the peripheral organs. Arousal threshold and secretion of melatonin and vasopressin increase at night-time to achieve high-quality sleep and minimize nocturnal urine production. In response to the increased vasopressin, the kidney reduces the glomerular filtration rate and facilitates the reabsorption of water. Synchronously, in the bladder, circadian oscillation of crucial molecules occurs to reduce afferent sensory input and maintain sufficient bladder capacity during the night sleep period. Thus, nocturia might occur as a result of desynchronization in one or more of these circadian regulatory mechanisms. Disrupted rhythmicity of the central nervous system, kidney and bladder (known as the brain-kidney-bladder circadian axis) contributes to the pathogenesis of nocturia. Novel insights into the chronobiological nature of nocturia will be crucial to promote a revolutionary shift towards effective therapeutics targeting the realignment of the circadian rhythm.

Allicin Improves Diet-Induced Nonalcoholic Steatohepatitis and Gut Microbiota Dysbiosis in Mice via the Involvement of the Circadian Clock Gene Rev-erbα

Nonalcoholic Steatohepatitis (NASH) is a progressive liver disease characterized by inflammation and liver damage. Allicin, a bioactive compound derived from garlic, has demonstrated anti-inflammatory and antioxidant properties. This study explores the effects of allicin on NASH and gut microbiota dysbiosis induced by a high-fat, high-fructose diet (HFFD) in mice. Allicin supplementation significantly alleviated hepatic inflammation, improved glucose metabolism, and modulated the circadian rhythm gene Rev-erbα, which plays a critical role in regulating inflammation. The anti-inflammatory effects of allicin were diminished in Si-Rev-erbα-treated HepG2 cells, highlighting the importance of circadian regulation in mediating these effects. Allicin's anti-inflammatory effects were associated with increased levels of short-chain fatty acids (SCFAs) and the restoration of diurnal oscillations in proinflammatory cytokines and gut microbiota composition, particularly in genera, such as Akkermansia, Bacteroidetes, and Lactobacillus. These findings suggest that allicin could be a promising therapeutic approach for managing NASH, liver dysfunction, and related metabolic disorders through the modulation of circadian rhythms and the gut microbiome.

Circadian Rhythm Dysregulation in Inflammatory Bowel Disease: Mechanisms and Chronotherapeutic Approaches

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD), is characterized by chronic intestinal inflammation. Recent research has highlighted the significant interplay between IBD pathogenesis and circadian rhythms. This review synthesizes current evidence regarding circadian regulation in IBD, covering three main areas: (1) circadian rhythms in intestinal physiology, (2) circadian disruption patterns in IBD patients, and (3) the role of clock genes in IBD pathogenesis. We discuss how these findings may inform novel chronotherapeutic approaches for IBD treatment. Future research directions that could facilitate translation of chronobiological insights into clinical applications are also explored.

Sleep loss is a metabolic disorder

Sleep loss dysregulates cellular metabolism and energy homeostasis. Highly metabolically active cells, such as neurons, enter a catabolic state during periods of sleep loss, which consequently disrupts physiological functioning. Specific to the central nervous system, sleep loss results in impaired synaptogenesis and long-term memory, effects that are also characteristic of neurodegenerative diseases. In this review, we describe how sleep deprivation increases resting energy expenditure, leading to the development of a negative energy balance-a state with insufficient metabolic resources to support energy expenditure-in highly active cells like neurons. This disruption of energetic homeostasis alters the balance of metabolites, including adenosine, lactate, and lipid peroxides, such that energetically costly processes, such as synapse formation, are attenuated. During sleep loss, metabolically active cells shunt energetic resources away from those processes that are not acutely essential, like memory formation, to support cell survival. Ultimately, these findings characterize sleep loss as a metabolic disorder.

Circadian rest-activity rhythms and multimorbidity and mortality risks among menopausal women: a trajectory analysis of a UK Biobank cohort

BACKGROUND

Menopausal women undergo substantial physiological changes that can impact their overall health.

OBJECTIVES

We examined relationships between circadian rest-activity rhythms (CRARs) and multimorbidity progression in this population.

METHODS

We used UK Biobank data, involving 10,138 participants, who were initially free of chronic conditions. We primarily focused on the relative amplitude (RA) of CRARs, tracking incident first chronic conditions (FCC), multimorbidity, and all-cause mortality. Multimorbidity was indicated by the presence of any 2/35 chronic conditions during the follow-up period. We used a multi-state model to assess the RA impact on the multimorbidity progression trajectory, encompassing transition from health to an FCC, to consequent multimorbidity, and ultimately to mortality, in parallel with sensitivity analyses to ensure results stability and reliability.

RESULTS

During a mean 8.13-year follow-up period, we identified 855 incident multimorbidity cases and recorded 88 deaths. In a multi-state model, a lower RA was associated with an increased risk of transition from health to FCC onset [hazard ratio (HR): 1.18, 95% confidence interval (CI): 1.07-1.31] and also from an FCC to multimorbidity development (HR: 1.34, 95% CI: 1.12-1.61), even after adjusting for several confounding factors.

CONCLUSIONS

Among menopausal women, circadian rhythm disturbance increased the risk of transitioning from health to a single chronic condition, as well as transitioning from a single chronic condition to multimorbidity.

DEC1 Regulates Human β Cell Functional Maturation and Circadian Rhythm

Stem cell-derived islet (SC-islet) organoids offer hope for cell replacement therapy in diabetes, but their immature function remains a challenge. Mature islet function requires the β-cell circadian clock, yet how the clock regulates maturation is unclear. Here, we show that a circadian transcription factor specific to maturing SC-β cells, DEC1, regulates insulin responsiveness to glucose. SC-islet organoids form normally from DEC1 -ablated human pluripotent stem cells, but their insulin release capacity and glucose threshold fail to increase during in vitro culture and upon transplant. This deficit reflects downregulation of maturity-linked effectors of glucose utilization and insulin exocytosis, blunting glycolytic and oxidative metabolism, and is rescued by increasing metabolic flux. Moreover, DEC1 is needed to boost SC-islet maturity by synchronizing circadian glucose-responsive insulin secretion rhythms and clock machinery. Thus, DEC1 links circadian control to human β-cell maturation, highlighting its vitality to foster fully functional SC-islets.

An adult clock regulator links circadian rhythms to pancreatic β-cell maturation

The circadian clock attunes metabolism to daily energy cycles, but how it regulates maturation of metabolic tissues is poorly understood. Here we show that DEC1, a clock transcription factor induced in adult islet β cells, coordinates their glucose responsiveness by synchronizing energetic and secretory rhythms. DEC1 binds and regulates maturity-linked genes to integrate insulin exocytosis with energy metabolism, and β-cell Dec1 ablation disrupts their transcription synchrony. Dec1-disrupted mice develop lifelong glucose intolerance and insulin deficiency, despite normal islet formation and intact Clock/Bmal1 genes. Metabolic dysfunction upon β-cell Dec1 loss stems from poor coupling of insulin secretion to glucose metabolism, reminiscent of fetal/neonatal immaturity. We link stunted maturation to a deficit in circadian bioenergetics, prompted by compromised glucose utilization, mitochondrial dynamics, and respiratory metabolism, which is rescued by increased metabolic flux. Thus, DEC1 links circadian clockwork to β-cell metabolic maturation, revealing a hierarchy for how the clock programs metabolic tissue specialization.

Circadian clockwork controls the balance between mitochondrial turnover and dynamics: What is life … without time marking?

Circadian rhythms driven by biological clocks regulate physiological processes in all living organisms by anticipating daily geophysical changes, thus enhancing environmental adaptation. Time-resolved serial multi-omic analyses in vivo, ex vivo, and in synchronized cell cultures have revealed rhythmic changes in the transcriptome, proteome, and metabolome, involving up to 50 % of the mammalian genome. Mitochondrial oxidative metabolism is central to cellular bioenergetics, and many nuclear genes encoding mitochondrial proteins exhibit both circadian and ultradian oscillatory expression. However, studies on mitochondrial DNA (mtDNA) gene expression remain incomplete. Using a well-established in vitro synchronization protocol, we investigated the time-resolved expression of mtDNA genes coding for respiratory chain complex subunits, revealing a rhythmic profile dependent on BMAL1, the master circadian clock transcription factor. Additionally, the expression of genes coding for key mitochondrial biogenesis transcription factors, PGC1a, NRF1, and TFAM, showed BMAL1-dependent circadian oscillations. Notably, LC3-II, involved in mitophagy, displayed a similar in-phase circadian expression, thereby maintaining stable respiratory chain complex levels. Moreover, we found that simultaneous mitochondrial biogenesis and degradation occur in a coordinated manner with cycles in organelle dynamics, leading to rhythmic changes in mitochondrial fission and fusion. This study provides new insights into circadian clock regulation of mitochondrial turnover, emphasizing the importance of temporal regulation in cellular metabolism. Understanding these mechanisms opens potential therapeutic avenues for targeting mitochondrial dysfunctions and related metabolic disorders.

Abundant clock proteins point to missing molecular regulation in the plant circadian clock

Understanding the biochemistry behind whole-organism traits such as flowering time is a longstanding challenge, where mathematical models are critical. Very few models of plant gene circuits use the absolute units required for comparison to biochemical data. We refactor two detailed models of the plant circadian clock from relative to absolute units. Using absolute RNA quantification, a simple model predicted abundant clock protein levels in Arabidopsis thaliana, up to 100,000 proteins per cell. NanoLUC reporter protein fusions validated the predicted levels of clock proteins in vivo. Recalibrating the detailed models to these protein levels estimated their DNA-binding dissociation constants (Kd). We estimate the same Kd from multiple results in vitro, extending the method to any promoter sequence. The detailed models simulated the Kd range estimated from LUX DNA-binding in vitro but departed from the data for CCA1 binding, pointing to further circadian mechanisms. Our analytical and experimental methods should transfer to understand other plant gene regulatory networks, potentially including the natural sequence variation that contributes to evolutionary adaptation.

Scheduled Exercise Partially Offsets Alcohol-Induced Clock Dysfunction in Skeletal Muscle and Liver of Female Mice

Binge and chronic alcohol intake impair skeletal muscle and liver circadian clocks. Scheduled exercise is suggested to protect against circadian misalignment, like that induced by alcohol. It was tested whether scheduled, voluntary daily wheel running would protect the gastrocnemius and liver clocks against alcohol-induced perturbations. Female C57BL6/Hsd mice were assigned to 1 of 4 groups: control-sedentary (CON SED, n = 26), control-exercise (CON EX, n = 28), alcohol-sedentary (ETOH SED, n = 27), or alcohol-exercise (ETOH EX, n = 25). Exercise mice were granted access to running wheels for 2 h/day (ZT13-15) while ETOH mice consumed alcohol-containing liquid diet for 6 weeks. Tissues were collected every 4 h starting at ZT12 from 4-5 mice/group and were used for RNA/cDNA/RT-PCR (gastrocnemius and liver) and Western blotting (gastrocnemius). A second cohort of mice were weaned off alcohol, given regular chow, and continued daily exercise (2 h/day) for ~2 weeks. Then, all mice (EX and SED) were given 24-h wheel access for 1 week to assess cyclic running behaviors during abstinence. While alcohol differentially disrupted muscle and liver clocks in sedentary mice, differences between exercised groups were minimized. BMAL1 protein expression increased in the nuclear-enriched fraction in the gastrocnemius of both exercise groups compared to both sedentary groups. In the second cohort, wheel running was increased in ETOH EX compared to ETOH SED in the dark cycle. In the light cycle, ETOH mice ran less than CON mice, and EX mice ran less than SED mice despite all mice receiving chow diet and no EtOH. Overall, scheduled wheel running partially offset the alcohol-induced perturbations in the muscle and liver clock while ETOH and EX both influenced the timing of subsequent activity after the dietary intervention ended.

Control of circadian muscle glucose metabolism through the BMAL1-HIF axis in obesity

Disruptions of circadian rhythms are widespread in modern society and lead to accelerated and worsened symptoms of metabolic syndrome. In healthy mice, the circadian clock factor BMAL1 is required for skeletal muscle function and metabolism. However, the importance of muscle BMAL1 in the development of metabolic diseases, such as diet-induced obesity (DIO), remains unclear. Here, we demonstrate that skeletal muscle-specific BMAL1-deficient mice exhibit worsened glucose tolerance upon high-fat diet feeding, despite no evidence of increased weight gain. Metabolite profiling from Bmal1-deficient muscles revealed impaired glucose utilization specifically at early steps in glycolysis that dictate the switch between anabolic and catabolic glucose fate. We provide evidence that this is due to abnormal control of the nutrient stress-responsive hypoxia-inducible factor (HIF) pathway. Genetic HIF1α stabilization in muscle Bmal1-deficient mice restores glucose tolerance and expression of 217/736 dysregulated genes during DIO, including glycolytic enzymes. Together, these data indicate that during DIO, skeletal muscle BMAL1 is an important regulator of HIF-driven glycolysis and metabolic flexibility, which influences the development of high-fat-diet-induced glucose intolerance.

The mediating role of the TyG index in the relationship between circadian syndrome and cancer among middle-aged and elderly Chinese

BACKGROUND

Circadian Syndrome (CircS) is a significant marker of metabolic imbalance and has been linked to various chronic diseases. However, its relationship with cancer risk remains underexplored. This research aims to explore the relationship between CircS and cancer, while also assessing the possible mediating role of the triglyceride glucose (TyG) index.

METHODS

Baseline data from the 2011 China Health and Retirement Longitudinal Study (CHARLS) and follow-up data from 2015 were analyzed, including participants' sociodemographic characteristics, health behaviors, and metabolic indicators. Linear regression, mediation analysis, and logistic regression were employed to explore relationships between CircS, cancer risk, and the TyG index, with a dose-response analysis conducted on TyG index and cancer risk.

RESULTS

Among 7,864 middle-aged and elderly participants, CircS was significantly and positively associated with cancer risk (r = 0.17, P < 0.001). The TyG index showed a significant correlation with both CircS (r = 0.52, P < 0.001) and cancer (r = 0.15, P < 0.001). Mediation modeling indicated that the TyG index partially mediated the association between CircS and cancer, accounting for 23% of this relationship. Additionally, a significant nonlinear dose-response relationship was observed between the TyG index and cancer risk (Pnonlinear = 0.0024).

CONCLUSION

Circadian syndrome is associated with increased cancer risk, with the TyG index partially mediating this relationship.

Dual orexin receptor antagonists as promising therapeutics for Alzheimer's disease

We examine the relationship between sleep, glymphatics and Alzheimer's disease (AD), and recent work questioning glymphatic clearance during sleep. We highlight a need for understanding glymphatic and/or other mechanism of clearance during sleep, and review glymphatic flow measurement methods. Further, we explore dual orexin receptor antagonists (DORAs) potential to mitigate AD sleep disturbances and enhance clearance. Further research could elucidate a linkage between DORAs, improved sleep and reducing AD pathophysiology.

Immunomodulatory role of the stem cell circadian clock in muscle repair

Circadian rhythms orchestrate physiological processes such as metabolism, immune function, and tissue regeneration, aligning them with the optimal time of day (TOD). This study identifies an interplay between the circadian clock within muscle stem cells (SCs) and their capacity to modulate the immune microenvironment during muscle regeneration. We reveal that the SC clock triggers TOD-dependent inflammatory gene transcription after injury, particularly genes related to neutrophil activity and chemotaxis. These responses are driven by cytosolic regeneration of the signaling metabolite nicotinamide adenine dinucleotide (oxidized form) (NAD+), as enhancing cytosolic NAD+ regeneration in SCs is sufficient to induce inflammatory responses that influence muscle regeneration. Mononuclear single-cell sequencing of the regenerating muscle niche further implicates the cytokine CCL2 in mediating SC-neutrophil cross-talk in a TOD-dependent manner. Our findings highlight the intersection between SC metabolic shifts and immune responses within the muscle microenvironment, dictated by circadian rhythms, and underscore the potential for targeting circadian and metabolic pathways to enhance tissue regeneration.

Identification of potential susceptibility loci for non-small cell lung cancer through whole genome sequencing in circadian rhythm genes

Lung cancer is a malignant tumor with a high morbidity and mortality rate worldwide, causing an increasing disease burden. Of these, the most common type is non-small cell lung cancer (NSCLC), which accounts for 80-85% of all lung cancer cases. Genetic research is crucial for continuously discovering susceptibility genes related to lung cancer for in-depth study. The role of genetic predisposition in the development of NSCLC, particularly within circadian rhythm pathways known to govern various physiological processes, is increasingly acknowledged. Yet, the association between genetic variants of circadian rhythm-related genes and NSCLC susceptibility among Chinese populations is not fully understood. This study carried out a two-phase (discovery and validation stages) research design to identify genetic variants associated with NSCLC risk within the circadian rhythm pathway. We employed extensive whole-genome sequencing (WGS) for 1,104 NSCLC cases and 9,635 controls. FastGWA-GLMM was used for single-locus risk association analysis of NSCLC, and we screened candidate SNPs in the validation set that comprised 4,444 cases and 174,282 controls from the Biobank Japan Project (BBJ). Furthermore, GCTA-COJO conditional analysis was utilized to confirm SNPs related to NSCLC risk. Finally, potential genetic variations that may regulate gene expression were explored in GTEx and QTLbase. RNA sequencing data were utilized for transcriptomic verification. Our study identified eight candidate SNPs associated with NSCLC susceptibility within the circadian rhythm pathway that met the requirement with P < 0.05 in both the discovery and validation populations. After conditional analysis, five of these SNPs remained. The A allele of CUL1 rs78524436 (ORmeta = 1.18, 95%CI: 1.09-1.29, Pmeta = 7.99e-5) and the A allele of TEF rs9611588 (ORmeta = 1.06, 95%CI: 1.02-1.10, Pmeta = 1.28e-3) were associated with an increased risk of NSCLC. The A allele of FBXL21 rs2069868 (ORmeta = 0.86, 95%CI: 0.80-0.96, Pmeta = 4.78e-4), the T allele of CSNK1D rs147316973 (ORmeta = 0.76, 95%CI: 0.65-0.88, Pmeta = 5.93e-4), and the A allele of RORA rs1589701 (ORmeta = 0.94, 95%CI: 0.91-0.98, Pmeta = 3.40e-3) were associated with a lower risk of NSCLC, separately. The eQTL results revealed an association between RORA rs1589701 and TEF rs9611588 with the expression levels of RORA and TEF, respectively. Transcriptome data indicated that RORA and TEF showed lower expression levels in tumor tissues compared to normal tissues (P < 0.001). Moreover, poorer survival was observed in patients with lower RORA and TEF expressions (log-rank P < 0.05). Our findings spotlight potential susceptibility loci within circadian rhythm pathway genes that modulate NSCLC carcinogenesis, which enriches the understanding of the genetic susceptibility of NSCLC in the Chinese population and provides a more solid basis for exploring the biological mechanism of circadian rhythm genes in NSCLC.

The time is now: accounting for time-of-day effects to improve reproducibility and translation of metabolism research

The constant expansion of the field of metabolic research has led to more nuanced and sophisticated understanding of the complex mechanisms that underlie metabolic functions and diseases. Collaborations with scientists of various fields such as neuroscience, immunology and drug discovery have further enhanced the ability to probe the role of metabolism in physiological processes. However, many behaviours, endocrine and biochemical processes, and the expression of genes, proteins and metabolites have daily ~24-h biological rhythms and thus peak only at specific times of the day. This daily variation can lead to incorrect interpretations, lack of reproducibility across laboratories and challenges in translating preclinical studies to humans. In this Review, we discuss the biological, environmental and experimental factors affecting circadian rhythms in rodents, which can in turn alter their metabolic pathways and the outcomes of experiments. We recommend that these variables be duly considered and suggest best practices for designing, analysing and reporting metabolic experiments in a circadian context.

Circadian rhythm, microglia-mediated neuroinflammation, and Alzheimer's disease

Microglia, the brain's resident macrophages, are key mediators of neuroinflammation, responding to immune pathogens and toxins. They play a crucial role in clearing cellular debris, regulating synaptic plasticity, and phagocytosing amyloid-β (Aβ) plaques in Alzheimer's disease (AD). Recent studies indicate that microglia not only exhibit intrinsic circadian rhythms but are also regulated by circadian clock genes, influencing specific functions such as phagocytosis and the modulation of neuroinflammation. Disruption of the circadian rhythm is closely associated with AD pathology. In this review, we will provide an overview of how circadian rhythms regulate microglia-mediated neuroinflammation in the progression of AD, focusing on the pathway from the central nervous system (CNS) and the peripheral immune system. We also discuss potential therapeutic targets, including hormone modulation, lifestyle interventions, and anti-inflammatory therapies, aimed at maintaining brain health in AD. This will shed light on the involvement of circadian rhythm in AD and explore new avenues for AD treatment.

A Compensated Clock: Temperature and Nutritional Compensation Mechanisms Across Circadian Systems

Circadian rhythms are ∼24-h biological oscillations that enable organisms to anticipate daily environmental cycles, so that they may designate appropriate day/night functions that align with these changes. The molecular clock in animals and fungi consists of a transcription-translation feedback loop, the plant clock is comprised of multiple interlocking feedback-loops, and the cyanobacterial clock is driven by a phosphorylation cycle involving three main proteins. Despite the divergent core clock mechanisms across these systems, all circadian clocks are able to buffer period length against changes in the ambient growth environment, such as temperature and nutrients. This defining capability, termed compensation, is critical to proper timekeeping, yet the underlying mechanism(s) remain elusive. Here we examine the known players in, and the current models for, compensation across five circadian systems. While compensation models across these systems are not yet unified, common themes exist across them, including regulation via temperature-dependent changes in post-translational modifications.

Understanding the mechanistic interlink between circadian misalignment and heart disease in night shift workers: Therapeutic role of behavioral interventions

BACKGROUND

Rotating and night shift work, especially in older workers, is a growing health concern of modern societies due to the associated high morbidity and mortality rates from cardiovascular disease (CVD). The resulting circadian misalignment disrupts neuroendocrine pathways that regulate cardiovascular physiology, risking myocardial tissue damage and heart dysfunction.

AIMS

Considering the gaps in the literature as to how atypical work behaviors may disrupt the temporal link between the central and myocardial oscillators at the level of the proteome and transcriptome, the primary goal of this review is to assess the molecular mechanisms linking disrupted biological rhythms to heart health, with a focus on core clock genes like BMAL1 and cardiac troponin I (cTnI) as a myocardial biomarker.

MAJOR FINDINGS

Circadian misalignment can lead to cognitive decline, metabolic dysfunction, and immune disruption, all of which elevate CVD risk. BMAL1 has a key role in maintaining cardiovascular integrity, with its dysfunction associated with hypertension, arrhythmias, and myocardial injury. Additionally, disrupted sleep patterns influence the expression of clock genes, potentially leading to altered heart function and elevated levels of cardiac biomarkers like troponin.

CONCLUSION

Circadian misalignment poses significant CVD risks, particularly for older workers. Future research should investigate how the expression of central and peripheral clock genes, as well as cardiac biomarkers is affected by shift work, especially in older individuals. Behavioral interventions such as chronotherapy, light therapy, and scheduled evening sleep may help mitigate these risks, but more studies are needed to assess their long-term effectiveness.

Integrated control of leukocyte compartments as a feature of adaptive physiology

As a highly diverse and mobile organ, the immune system is uniquely equipped to participate in tissue responses in a tunable manner, depending on the number, type, and nature of cells deployed to the respective organ. Most acute organismal stressors that threaten survival-predation, infection, poisoning, and others-induce pronounced redistribution of immune cells across tissue compartments. Here, we review the current understanding of leukocyte compartmentalization under homeostatic and noxious conditions. We argue that leukocyte shuttling between compartments is a function of local tissue demands, which are linked to the organ's contribution to adaptive physiology at steady state and upon challenge. We highlight the neuroendocrine signals that relay and organize this trafficking behavior and outline mechanisms underlying the functional diversification of leukocyte responses. In this context, we discuss important areas of future inquiry and the implications of this scientific space for clinical medicine in the era of targeted immunomodulation.

Towards the recognition of oligogenic forms of type 2 diabetes

The demarcation between monogenic and polygenic type 2 diabetes (T2D) is less distinct than previously believed. Notably, recent research has highlighted a new entity, that we suggest calling oligogenic forms of T2D, serving as a genetic link between these two forms. In this opinion article, we have reviewed scientific advances that suggest categorizing genes involved in oligogenic T2D. Research focused on polygenic T2D has faced challenges in deepening our comprehension of the pathophysiology of T2D due to the inability to directly establish causal links between a signal and the molecular mechanisms underlying the disease. However, the study of oligogenic forms of T2D has illuminated distinct causal connections between genes and disease risk, thereby indicating potential new drug targets.

Time for bed: diet, sleep and obesity in children and adults

Sufficient sleep is necessary for optimal health, daytime performance and wellbeing and the amount required is age-dependent and decreases across the lifespan. Sleep duration is usually affected by age and several different cultural, social, psychological, behavioural, pathophysiological and environmental factors. This review considers how much sleep children and adults need, why this is important, what the consequences are of insufficient sleep and how we can improve sleep. A lack of the recommended amount of sleep for a given age group has been shown to be associated with detrimental effects on health including effects on metabolism, endocrine function, immune function and haemostatic pathways. Obesity has increased worldwide in the last few decades and the WHO has now declared it a global epidemic. A lack of sleep is associated with an increased risk of obesity in children and adults, which may lead to future poor health outcomes. Data from studies in both children and adults suggest that the relationship between sleep and obesity may be mediated by several different mechanisms including alterations in appetite and satiety, sleep timing, circadian rhythm and energy balance. Moreover, there is evidence to suggest that improvements in sleep, in both children and adults, can be beneficial for weight management and diet and certain foods might be important to promote sleep. In conclusion this review demonstrates that there is a wide body of evidence to suggest that sleep and obesity are causally related and recommends that further research is required to inform policy, and societal change.

High sleep reactivity in shift workers is associated with increased sleep disturbance, mood problems, and reduced quality of life

INTRODUCTION

Shift work disrupts circadian rhythms, causing sleep and mood problems. Sleep reactivity-the sensitivity of sleep to stress-may affect how shift workers cope with these disruptions. This study investigated the relationship between sleep reactivity and shift work, exploring associations between sleep reactivity and sleep disturbance, mood symptoms, and quality of life in shift workers.

METHODS

In a cross-sectional design, 132 participants (79 shift workers and 53 controls) were assessed using the Ford Insomnia Response to Stress Test (FIRST), Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and World Health Organization Quality of Life (WHOQOL). We compared the self-reported measurements between shift workers and controls. Two-way ANOVA was performed to explore the interaction effects between shift work and sleep reactivity on sleep, mood parameters, and quality of life. Multiple linear regression analysis was conducted to identify factors associated with sleep, mood, and quality of life among shift workers.

RESULTS

Shift workers scored higher on ISI and BDI compared to controls. Two-way ANOVA revealed an interaction effect between shift work and sleep reactivity on WHOQOL. Regression analysis indicated that high sleep reactivity was associated with higher ISI, BDI, BAI, and lower WHOQOL among shift workers.

CONCLUSION

Sleep reactivity significantly affected shift worker's quality of life. Our findings indicate that high sleep reactivity in shift workers was associated with increased sleep disturbance, mood problems, and decreased quality of life, implying that sleep reactivity may predict shift work tolerance.

Circadian rhythms: pervasive, and often times evasive

Most circadian texts begin by stating that clocks are pervasive throughout the tree of life. Indeed, clock mechanisms have been described from cyanobacteria to humans, representing a notable example of convergent evolution: yet, there are several phyla in animals, protists or within fungi and bacteria, in which homologs of some-or all-known clock components seem to be absent, posing inevitable questions about the evolution of circadian systems. Moreover, as we move away from model organisms, there are several taxa in which core clock elements can be identified at the genomic levels. However, the functional description of those putative clocks has been hard to achieve, as rhythmicity is not observed unless defined abiotic or nutritional cues are provided. The mechanisms 'conditioning' the functionality of clocks remain uncertain, emphasizing the need to delve further into non-model circadian systems. As the absence of evidence is not evidence of absence, the lack of known core-clock homologs or of observable rhythms in a given organism, cannot be an a priori criterion to discard the presence of a functional clock, as rhythmicity may be limited to yet untested experimental conditions or phenotypes. This article seeks to reflect on these topics, highlighting some of the pressing questions awaiting to be addressed.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Chrononutrition in Chronic Kidney Disease

Chrononutrition, the study of the interaction between biological rhythms and nutrition, has emerged as a promising field for addressing metabolic health. However, its role in chronic kidney disease (CKD) remains underexplored. CKD patients often experience circadian disruptions due to renal, metabolic, treatment-related, and lifestyle factors, which may influence their nutritional status and clinical outcomes. Objective: to synthesize and analyze the existing evidence on chrononutrition in CKD patients, identify knowledge gaps, and propose directions for future research across different stages of CKD. Initially, this review contextualizes circadian physiology, alignment, and chronodisruption to explore such factors in CKD patients, focusing on chrononutrition variables already studied in the general population. We discuss how dietary timing and habit adjustments could influence CKD clinical outcomes, offering insights into circadian impacts on disease management. This new approach could optimize patient care, encouraging further research, particularly in the development of personalized strategies for different stages of the disease.

Chronic low-dose REV-ERBs agonist SR9009 mitigates constant light-induced weight gain and insulin resistance via adipogenesis modulation

BACKGROUND

Obesity and circadian rhythm disruption are significant global health concerns, contributing to an increased risk of metabolic disorders. Both adipose tissue and circadian rhythms play critical roles in maintaining energy homeostasis, and their dysfunction is closely linked to obesity. This study aimed to assess the effects of chronic low-dose SR9009, a REV-ERB ligand, on circadian disruption induced by constant light exposure in mice.

MATERIAL AND METHODS

Mice were exposed to constant light for eight weeks (LL mice), resulting in increased body weight, insulin resistance, white fat mass, and altered circadian clock gene expression. Low-dose SR9009 (10 mg/kg daily) was administered chronically to assess its impact on these metabolic disruptions.

RESULTS

LL mice treated with SR9009 for eight weeks showed reduced weight gain, insulin resistance, and white fat mass but no significant impact on overall energy homeostasis. SR9009 suppressed Bmal1 expression and restored Rev-erbα and Rev-erbβ expression in white and brown adipose tissue (WAT and BAT). In vitro studies using 3T3-L1 cells indicated that SR9009 inhibited adipogenesis, leading to further investigation in vivo. SR9009 restored ChREBP1a and Srebp-1c expression in BAT but did not affect inflammatory cytokine or adipokine gene expression, nor did it restore Fasn, Pparγ, and Prom1 expression in both WAT and BAT.

CONCLUSIONS

These findings suggest that SR9009 may be a potential therapeutic approach for preventing weight gain and insulin resistance caused by circadian disruptions, likely through adipogenesis inhibition, though its effects on other metabolic pathways remain limited at low doses.

Circadian rhythm and immunity: decoding chrono-immunology using the model organism Drosophila melanogaster

Circadian rhythms are important cellular pathways first described for their essential role in helping organisms adjust to the 24 h day-night cycle and synchronize physiological and behavioral functions. Most organisms have evolved a circadian central clock to anticipate daily environmental changes in light, temperature, and mate availability. It is now understood that multiple clocks exist in organisms to regulate the functions of specific organs. Epidemiological studies in humans reported that disruption of the circadian rhythms caused by sleep deprivation is linked to the onset of immune-related conditions, suggesting the importance of circadian regulation of immunity. Mechanistic studies to define how circadian clocks and immune responses interact have profound implications for human health. However, elucidating the clocks and their tissue-specific functions has been challenging in mammals. Many studies using simple model organisms such as Drosophila melanogaster have been pioneering in discovering that the clock controls innate immune responses and immune challenges can impact circadian rhythms and/or their outcomes. In this review, we will report genetic studies using the humble fruit fly that identified the existence of reciprocal interactions between the circadian pathway and innate immune signaling, contributing to elucidate mechanisms in the growing field of chrono-immunology.

Single-cell and Bulk Transcriptomic Analyses Reveal a Stemness and Circadian Rhythm Disturbance-related Signature Predicting Clinical Outcome and Immunotherapy Response in Hepatocellular Carcinoma

AIMS

Investigating the impact of stemness-related circadian rhythm disruption (SCRD) on hepatocellular carcinoma (HCC) prognosis and its potential as a predictor for immunotherapy response.

BACKGROUND

Circadian disruption has been linked to tumor progression through its effect on the stemness of cancer cells.

OBJECTIVE

Develop a novel signature for SCRD to accurately predict clinical outcomes and immune therapy response in patients with HCC.

METHODS

The stemness degree of patients with HCC was assessed based on the stemness index (mRNAsi). The co-expression circadian genes significantly correlated with mRNAsi were identified and defined as stemness- and circadian-related genes (SCRGs). The SCRD scores of samples and cells were calculated based on the SCRGs. Differentially expressed genes with a prognostic value between distinct SCRD groups were identified in bulk and single-cell datasets to develop an SCRD signature.

RESULTS

A higher SCRD score indicates a worse patient survival rate. Analysis of the tumor microenvironment revealed a significant correlation between SCRD and infiltrating immune cells. Heterogeneous expression patterns, functional states, genomic variants, and cell-cell interactions between two SCRD populations were revealed by transcriptomic, genomic, and interaction analyses. The robust SCRD signature for predicting immunotherapy response and prognosis in patients with HCC was developed and validated in multiple independent cohorts.

CONCLUSIONS

In summary, distinct tumor immune microenvironment patterns were confirmed under SCRD in bulk and single-cell transcriptomic, and SCRD signature associated with clinical outcomes and immunotherapy response was developed and validated in HCC.

Gut microbiota and eating behaviour in circadian syndrome

Eating behaviour and circadian rhythms are closely related. The type, timing, and quantity of food consumed, and host circadian rhythms, directly influence the intestinal microbiota, which in turn impacts host circadian rhythms and regulates food intake beyond homeostatic eating. This Opinion discusses the impact of food intake and circadian disruptions induced by an obesogenic environment on gut-brain axis signalling. We also explore potential mechanisms underlying the effects of altered gut microbiota on food intake behaviour and circadian rhythmicity. Understanding the crosstalk between gut microbiota, circadian rhythms, and unhealthy eating behaviour is crucial to addressing the obesity epidemic, which remains one of the biggest societal challenges of our time.

The chronobiology of human heart failure: clinical implications and therapeutic opportunities

Circadian variation in cardiovascular and metabolic dynamics arises from interactions between intrinsic rhythms and extrinsic cues. By anticipating and accommodating adaptation to awakening and activity, their synthesis maintains homeostasis and maximizes efficiency, flexibility, and resilience. The dyssynchrony of cardiovascular load and energetic capacity arising from attenuation or loss of such rhythms is strongly associated with incident heart failure (HF). Once established, molecular, neurohormonal, and metabolic rhythms are frequently misaligned with each other and with extrinsic cycles, contributing to HF progression and adverse outcomes. Realignment of biological rhythms via lifestyle interventions, chronotherapy, and time-tailored autonomic modulation represents an appealing potential strategy for improving HF-related morbidity and mortality.

The effect of light therapy on insomnia: A systematic review and meta-analysis

PURPOSE

Light is a crucial factor influencing sleep arousal patterns. This meta-analysis investigates the efficacy of light therapy (LT) for insomnia treatment.

METHODS

Five electronic databases were independently searched by two reviewers until August 2024. The literature screening focused specifically on populations with insomnia complaints treated by LT. Weighted Mean Difference (WMD) and 95% Confidence Interval (CI) were used as statistical tools, while the Cochrane Risk of Bias tool version 2 (RoB 2) was employed to assess the quality of evidence. A total of 10 randomized controlled trials (RCTs) were analyzed.

RESULTS

The results demonstrated that LT showed statistically significant improvements in subjective sleep quality, as evidenced by a reduction in Pittsburgh sleep quality scale (PSQI) scores by -2.89 (95% CI = -4.80 to -0.97) and Insomnia severity index (ISI) scores by -2.16 (95% CI = -4.23 to -0.08) post-intervention. Additionally, actigraphy revealed a statistically significant increase in total sleep time (TST) by 16.78 min (95% CI = 0.67 to 32.89) and a decrease in wake after sleep onset (WASO) by -12.91 min (95% CI = -25.62 to -0.20) by LT.

CONCLUSION

The preliminary results of the study suggest that LT has some efficacy in improving sleep quality in insomnia. However, it needs to be validated in future clinical trials with larger samples.

Knockdown of RASD1 improves MASLD progression by inhibiting the PI3K/AKT/mTOR pathway

BACKGROUND

There is still no reliable therapeutic targets and effective pharmacotherapy for metabolic dysfunction-associated steatotic liver disease (MASLD). RASD1 is short for Ras-related dexamethasone-induced 1, a pivotal factor in various metabolism processes of Human. However, the role of RASD1 remains poorly illustrated in MASLD. Therefore, we designed a study to elucidate how RASD1 could impact on MASLD as well as the mechanisms involved.

METHODS

The expression level of RASD1 was validated in MASLD. Lipid metabolism and its underlying mechanism were investigated in hepatocytes and mice with either overexpression or knockdown of RASD1.

RESULTS

Hepatic RASD1 expression was upregulated in MASLD. Lipid deposition was significantly reduced in RASD1-knockdown hepatocytes and mice, accompanied by a marked downregulation of key genes in the signaling pathway of de novo lipogenesis. Conversely, RASD1 overexpression in hepatocytes had the opposite effect. Mechanistically, RASD1 regulated lipid metabolism in MASLD through the PI3K/AKT/mTOR signaling pathway.

CONCLUSIONS

We discovered a novel role of RASD1 in MASLD by regulating lipogenesis via the PI3K/AKT/mTOR pathway, thereby identifying a potential treatment target for MASLD.

Circadian Influences on Brain Lipid Metabolism and Neurodegenerative Diseases

Circadian rhythms are intrinsic, 24 h cycles that regulate key physiological, mental, and behavioral processes, including sleep-wake cycles, hormone secretion, and metabolism. These rhythms are controlled by the brain's suprachiasmatic nucleus, which synchronizes with environmental signals, such as light and temperature, and consequently maintains alignment with the day-night cycle. Molecular feedback loops, driven by core circadian "clock genes", such as Clock, Bmal1, Per, and Cry, are essential for rhythmic gene expression; disruptions in these feedback loops are associated with various health issues. Dysregulated lipid metabolism in the brain has been implicated in the pathogenesis of neurological disorders by contributing to oxidative stress, neuroinflammation, and synaptic dysfunction, as observed in conditions such as Alzheimer's and Parkinson's diseases. Disruptions in circadian gene expression have been shown to perturb lipid regulatory mechanisms in the brain, thereby triggering neuroinflammatory responses and oxidative damage. This review synthesizes current insights into the interconnections between circadian rhythms and lipid metabolism, with a focus on their roles in neurological health and disease. It further examines how the desynchronization of circadian genes affects lipid metabolism and explores the potential mechanisms through which disrupted circadian signaling might contribute to the pathophysiology of neurodegenerative disorders.

Circadian disruption and its impact on the cardiovascular system

Circadian rhythms are highly conserved biorhythms of ~24 h that govern many fundamental biological processes, including cardiovascular (CV) homeostasis. Disrupting the timing of cellular oscillators promotes cellular stress, and induction of pathogenic pathways underpins the pathogenesis of many CV diseases (CVDs). Thus, shift work, late eating, sleep disturbances, and other disruptors can result in an elevated risk of heart disease and increased incidence of adverse CV events. Here, we discuss the importance of circadian rhythms for CV homeostasis, recent developments in understanding the impact of disrupted circadian rhythms on CV health and disease progression, and how understanding the interactions between circadian and CV physiology is crucial for improving interventions to mitigate CVD, especially in populations impacted by disrupted circadian rhythms.

LncRNA-MSTRG.19083.1 Targets NTRK2 as a miR-429-y Sponge to Regulate Circadian Rhythm via the cAMP Pathway in Yak Testis and Cryptorchidism

Long noncoding RNAs (LncRNAs) play essential roles in numerous biological processes in mammals, such as reproductive physiology and endocrinology. Cryptorchidism is a common male reproductive disease. Circadian rhythms are actively expressed in the reproductive system. In this study, a total of 191 LncRNAs were obtained from yak testes and cryptorchids. Then, we identified NTRK2's relationship to circadian rhythm and behavioral processes. Meanwhile, the ceRNA (LncRNA-MSTRG.19083.1/miR-429-y/NTRK2) network was constructed, and its influence on circadian rhythm was revealed. The results showed that NTRK2 and LncRNA-MSTRG.19083.1 were significantly upregulated, and miR-429-y was obviously decreased in cryptorchid tissue; NTRK2 protein was mainly distributed in the Leydig cells of the testis. In addition, the upregulation of the expression level of miR-429-y resulted in the significant downregulation of LncRNA and NTRK2 levels, while the mRNA and protein levels of CREB, CLOCK, and BMAL1 were significantly upregulated; the knockdown of miR-429-y resulted in the opposite changes. Our findings suggested that LncRNA-MSTRG.19083.1 competitively binds to miR-429-y to target NTRK2 to regulate circadian rhythm through the cAMP pathway. Taken together, the results of our study provide a comprehensive understanding of how the LncRNA-miRNA-mRNA networks operate when yak cryptorchidism occurs. Knowledge of circadian-rhythm-associated mRNAs and LncRNAs could be useful for better understanding the relationship between circadian rhythm and reproduction.

Circadian rhythms and cancer: implications for timing in therapy

Circadian rhythms, intrinsic cycles spanning approximately 24 h, regulate numerous physiological processes, including sleep-wake cycles, hormone release, and metabolism. These rhythms are orchestrated by the circadian clock, primarily located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Disruptions in circadian rhythms, whether due to genetic mutations, environmental factors, or lifestyle choices, can significantly impact health, contributing to disorders such as sleep disturbances, metabolic syndrome, and cardiovascular diseases. Additionally, there is a profound link between the disruption of circadian rhythms and development of various cancer, the influence on disease incidence and progression. This incurred regulation by circadian clock on pathways has its implication in tumorigenesis, such as cell cycle control, DNA damage response, apoptosis, and metabolism. Furthermore, the circadian timing system modulates the efficacy and toxicity of cancer treatments. In cancer treatment, the use of chronotherapy to optimize the timing of medical treatments, involves administering chemotherapy, radiation, or other therapeutic interventions at specific intervals to enhance efficacy and minimize side effects. This approach capitalizes on the circadian variations in cellular processes, including DNA repair, cell cycle progression, and drug metabolism. Preclinical and clinical studies have demonstrated that chronotherapy can significantly improve the therapeutic index of chemotherapeutic agents like cisplatin and 5-fluorouracil by enhancing anticancer activity and reducing toxicity. Further research is needed to elucidate the mechanisms underlying circadian regulation of cancer and to develop robust chronotherapeutic protocols tailored to individual patients' circadian profiles, potentially transforming cancer care into more effective and personalized treatment strategies.

Light modulates glucose and lipid homeostasis via the sympathetic nervous system

Light is an important environmental factor for vision and for diverse physiological and psychological functions. Light can also modulate glucose metabolism. Here, we show that in mice, light is critical for glucose and lipid homeostasis by regulating the sympathetic nervous system, independent of circadian disruption. Light deprivation from birth elicits insulin hypersecretion, glucagon hyposecretion, lower gluconeogenesis, and reduced lipolysis by 6 to 8 weeks in male, but not female, mice. These metabolic defects are consistent with blunted sympathetic activity, and indeed, sympathetic responses to a cold stimulus are substantially attenuated in dark-reared mice. Further, long-term dark rearing leads to body weight gain, insulin resistance, and glucose intolerance. Notably, metabolic dysfunction can be partially alleviated by 5 weeks exposure to a regular light-dark cycle. These studies provide insight into circadian-independent mechanisms by which light directly influences whole-body physiology and better understanding of metabolic disorders linked to aberrant environmental light conditions.

Circadian Rhythms of Clock Genes After Transplantation of Mesenchymal Stem Cells with Type 2 Diabetes Mellitus

Regenerative therapy involving stem cell transplantation has become an option for the radical treatment of diabetes mellitus. Disruption in the clock genes of stem cells affects the homeostasis of transplanted tissues. We examined the circadian rhythm of genes in transplanted adipose-derived mesenchymal stem cells derived from a patient with type 2 diabetes mellitus (T2DM-ADSC). The clock genes (PER2, CLOCK1, CRY1, and ARNTL[BMAL1]) exhibited similar daily fluctuations in phase and amplitude between a group transplanted with adipose-derived mesenchymal stem cells derived from a healthy individual (N-ADSC) and a group transplanted with T2DM-ADSC. The findings demonstrated that clock genes in stem cells are synchronized with those in living organisms. Next-generation sequencing was then employed to categorize genes that exhibited variation in expression between N-ADSC and T2DM-ADSC. MTATP8P1 and NDUFA7_2 gene expression was significantly reduced at two time points (ZT6 and ZT18), and daily fluctuations were lost. The present study reports, for the first time, that the circadian rhythms of MTATP8P1 and NDUFA7_2, genes involved in mitochondrial processes, are altered in T2DM-ADSC.

Alterations in Circadian Rhythms, Sleep, and Physical Activity in COVID-19: Mechanisms, Interventions, and Lessons for the Future

Although the world is acquitting from the throes of COVID-19 and returning to the regularity of life, its effects on physical and mental health are prominently evident in the post-pandemic era. The pandemic subjected us to inadequate sleep and physical activities, stress, irregular eating patterns, and work hours beyond the regular rest-activity cycle. Thus, perturbing the synchrony of the regular circadian clock functions led to chronic psychiatric and neurological disorders and poor immunological response in several COVID-19 survivors. Understanding the links between the host immune system and viral replication machinery from a clock-infection biology perspective promises novel avenues of intervention. Behavioral improvements in our daily lifestyle can reduce the severity and expedite the convalescent stage of COVID-19 by maintaining consistent eating, sleep, and physical activity schedules. Including dietary supplements and nutraceuticals with prophylactic value aids in combating COVID-19, as their deficiency can lead to a higher risk of infection, vulnerability, and severity of COVID-19. Thus, besides developing therapeutic measures, perpetual healthy practices could also contribute to combating the upcoming pandemics. This review highlights the impact of the COVID-19 pandemic on biological rhythms, sleep-wake cycles, physical activities, and eating patterns and how those disruptions possibly contribute to the response, severity, and outcome of SARS-CoV-2 infection.