Circadian adaptation to cell injury stresses: a crucial interplay of BMAL1 and HSF1

The hidden rhythms of epilepsy: exploring biological clocks and epileptic seizure dynamics

Epilepsy, characterized by recurrent seizures, is influenced by biological rhythms, such as circadian, seasonal, and menstrual cycles. These rhythms affect the frequency, severity, and timing of seizures, although the precise mechanisms underlying these associations remain unclear. This review examines the role of biological clocks, particularly the core circadian genes Bmal1, Clock, Per, and Cry, in regulating neuronal excitability and epilepsy susceptibility. We explore how the sleep-wake cycle, particularly non-rapid eye movement sleep, increases the risk of seizures, and discuss the circadian modulation of neurotransmitters like gamma-aminobutyric acid and glutamate. We explore clinical implications, including chronotherapy which refers to the practice of timing medical treatments to align with the body's natural biological rhythms, such as the circadian rhythm. Chronotherapy aligns anti-seizure medication administration with biological rhythms. We also discuss rhythm-based neuromodulation strategies, such as adaptive deep brain stimulation, which may dynamically change stimulation in response to predicted seizures in patients, provide additional therapeutic options. This review emphasizes the potential of integrating biological rhythm analysis into personalized epilepsy management, offering novel approaches to optimize treatment and improve patient outcomes. Future research should focus on understanding individual variability in seizure rhythms and harnessing technological innovations to enhance seizure prediction, precision treatment, and long-term management.

Denervation aggravates renal ischemia reperfusion injury via BMAL1-mediated Nrf2/ARE pathway

AIM

To explore the change of clock gene rhythm under renal denervation (RDN) and its effect on renal function and oxidative stress during renal ischemia-reperfusion (IR) injury.

METHOD

C57/BL6 mice were randomly divided into 4 groups at daytime 7 A M (zeitgeber time [ZT] 0) or at nighttime 7 P M (ZT12) in respectively: Sham (S) group, RDN group, IR group and RDN + IR (DIR) group. Renal pathological and functional changes were assessed by H&E staining, and serum creatinine, urea nitrogen and neutrophil gelatinase-associated lipocalin levels. Renal oxidative stress was detected by SOD and MDA levels, and renal inflammation was measured by IL-6, IL-17 A F and TNF-ɑ levels. BMAL1, CLOCK, Nrf2 and HO-1 mRNA and protein expressions were tested by qPCR and Western Blot.

RESULT

Compared with S groups, the rhythm of BMAL1, CLOCK and Nrf2 genes in the kidney were disordered in RDN groups, while renal pathological and functional indexes did not change significantly. Compared with IR groups, renal pathological and functional indexes were significantly higher in the DIR groups, as well as oxidative stress and inflammation in renal tissues. The nocturnal IR injury in the RDN kidney was the worst while the BMAL1, Nrf2 and HO-1 expressions were the highest. In DIR groups, renal injury was aggravated after the Brusatol treatment, but there was no significant improvement after the t-BHQ treatment at night, which might be consistent with the changes of Nrf2 and HO-1 protein expressions.

CONCLUSION

RDN lead to the disruption of BMAL1-mediated Nrf2 rhythm accumulation in the kidney, which reduced the renal ability to resist oxidative stress and inflammation, due to the impaired effect of activating Nrf2/ARE pathway in renal IR injury at nighttime.

Adaptive and Pathological Outcomes of Radiation Stress-Induced Redox Signaling

Significance: Ionizing radiation can damage cells either directly or through oxidative damage caused by ionization. Although radiation exposure from natural sources is very limited, ionizing radiation in nuclear disaster zones and long spaceflights causes inconspicuous, yet measurable physiological effects in men and animals, whose significance remains poorly known. Understanding the physiological impacts of ionizing radiation has a wide importance due to the increased use of medical imaging and radiotherapy. Recent Advances: Radiation exposure has been traditionally investigated from the perspective of DNA damage and its consequences. However, recent studies from Chernobyl as well as spaceflights have provided interesting insights into oxidative stress-induced metabolic alterations and disturbances in the circadian regulation. Critical Issues: In this review, we discuss the physiological consequences of radiation exposure in the light of oxidative stress signaling. Radiation exposure likely triggers many converging or interconnecting signaling pathways, some of which mimic mitochondrial dysfunction and might explain the observed metabolic changes. Future Directions: Better understanding of the different radiation-induced signaling pathways might help to devise strategies for mitigation of the long-term effects of radiation exposure. The utility of fibroblast growth factor 21 (FGF21) as a radiation exposure biomarker and the use of radiation hormesis as a method to protect astronauts on a prolonged spaceflight, such as a mission to Mars, should be investigated. Antioxid. Redox Signal. 37, 336-348.

Emerging Insight Into the Role of Circadian Clock Gene BMAL1 in Cellular Senescence

Cell senescence is a crucial process in cell fate determination and is involved in an extensive array of aging-associated diseases. General perceptions and experimental evidence point out that the decline of physical function as well as aging-associated diseases are often initiated by cell senescence and organ ageing. Therefore, regulation of cell senescence process can be a promising way to handle aging-associated diseases such as osteoporosis. The circadian clock regulates a wide range of cellular and physiological activities, and many age-linked degenerative disorders are associated with the dysregulation of clock genes. BMAL1 is a core circadian transcription factor and governs downstream genes by binding to the E-box elements in their promoters. Compelling evidence has proposed the role of BMAL1 in cellular senescence and aging-associated diseases. In this review, we summarize the linkage between BMAL1 and factors of cell senescence including oxidative stress, metabolism, and the genotoxic stress response. Dysregulated and dampened BMAL1 may serve as a potential therapeutic target against aging- associated diseases.

Comprehensive RNA-Seq Profiling Reveals Temporal and Tissue-Specific Changes in Gene Expression in Sprague-Dawley Rats as Response to Heat Stress Challenges

Understanding heat stress physiology and identifying reliable biomarkers are paramount for developing effective management and mitigation strategies. However, little is known about the molecular mechanisms underlying thermal tolerance in animals. In an experimental model of Sprague–Dawley rats subjected to temperatures of 22 ± 1°C (control group; CT) and 42°C for 30 min (H30), 60 min (H60), and 120 min (H120), RNA-sequencing (RNA-Seq) assays were performed for blood (CT and H120), liver (CT, H30, H60, and H120), and adrenal glands (CT, H30, H60, and H120). A total of 53, 1,310, and 1,501 differentially expressed genes (DEGs) were significantly identified in the blood (P < 0.05 and |fold change (FC)| >2), liver (P < 0.01, false discovery rate (FDR)–adjusted P = 0.05 and |FC| >2) and adrenal glands (P < 0.01, FDR-adjusted P = 0.05 and |FC| >2), respectively. Of these, four DEGs, namely Junb, P4ha1, Chordc1, and RT1-Bb, were shared among the three tissues in CT vs. H120 comparison. Functional enrichment analyses of the DEGs identified in the blood (CT vs. H120) revealed 12 biological processes (BPs) and 25 metabolic pathways significantly enriched (FDR = 0.05). In the liver, 133 BPs and three metabolic pathways were significantly detected by comparing CT vs. H30, H60, and H120. Furthermore, 237 BPs were significantly (FDR = 0.05) enriched in the adrenal glands, and no shared metabolic pathways were detected among the different heat-stressed groups of rats. Five and four expression patterns (P < 0.05) were uncovered by 73 and 91 shared DEGs in the liver and adrenal glands, respectively, over the different comparisons. Among these, 69 and 73 genes, respectively, were proposed as candidates for regulating heat stress response in rats. Finally, together with genome-wide association study (GWAS) results in cattle and phenome-wide association studies (PheWAS) analysis in humans, five genes (Slco1b2, Clu, Arntl, Fads1, and Npas2) were considered as being associated with heat stress response across mammal species. The datasets and findings of this study will contribute to a better understanding of heat stress response in mammals and to the development of effective approaches to mitigate heat stress response in livestock through breeding.

The Circadian Clock Regulates the Expression of the Nuclear Factor Erythroid 2-Related Factor 2 in Acute Kidney Injury following Myocardial Ischemia-Reperfusion in Diabetic Rat

Cardiac surgery-associated acute kidney injury (AKI) is a serious and frequent complication with poor prognosis, and disruption in circadian rhythm shall adversely influence cardiovascular and renal functions via oxidative stress mechanisms. However, the role of circadian clock genes (circadian locomotor output cycle kaput (CLOCK) and brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein-1 (BMAL1)) and its interaction with nuclear factor erythroid 2-related factor 2 (Nrf2) in AKI following myocardial ischemia-reperfusion (MIR) in the diabetic rat has not yet been explored. In this study, rats were divided into the sham (S) group, MIR (M) group, diabetic (D) group, and diabetic+MIR (DM) group. At light (zeitgeber time (ZT) 0) and dark time points (ZT12), rat MIR model was established by occlusion of the left anterior descending coronary artery for 30 min followed by 2 -hour reperfusion, and then renal injury was evaluated. The renal histological changes in the DM group were significantly high compared to other groups; serum creatinine, blood urea nitrogen, and neutrophil gelatinase-associated lipocalin levels, as well as malondialdehyde and 8-iso-prostaglandin-F2α levels in renal tissues of M ZT12 and DM ZT12 subgroups, were significantly higher than those of M ZT0 and DM ZT0 subgroups, individually indicating increased oxidative stress at a dark cycle. Further, Nrf2 protein accumulated in a circadian manner with decreasing levels at night in the DM and M groups. In conclusion, renal injury following MIR was exacerbated in the diabetic rat at night through molecular mechanisms involving transcriptional control of the circadian clock on light-dark activation of Nrf2.

Cooperative interaction among BMAL1, HSF1, and p53 protects mammalian cells from UV stress

The circadian clock allows physiological systems to adapt to their changing environment by synchronizing their timings in response to external stimuli. Previously, we reported clock-controlled adaptive responses to heat-shock and oxidative stress and showed how the circadian clock interacts with BMAL1 and HSF1. Here, we present a similar clock-controlled adaptation to UV damage. In response to UV irradiation, HSF1 and tumor suppressor p53 regulate the expression of the clock gene Per2 in a time-dependent manner. UV irradiation first activates the HSF1 pathway, which subsequently activates the p53 pathway. Importantly, BMAL1 regulates both HSF1 and p53 through the BMAL1-HSF1 interaction to synchronize the cellular clock. Based on these findings and transcriptome analysis, we propose that the circadian clock protects cells against the UV stress through sequential and hierarchical interactions between the circadian clock, the heat shock response, and a tumor suppressive mechanism.

zHSF1 modulates zper2 expression in zebrafish embryos

HSF1 is a transcription factor that plays a key role in circadian resetting by temperature. We have used zebrafish embryos to decipher the roles of zHsf1, heat and light on zper2 transcription in vivo. Our results show that heat shock (HS) stimulated zper2 expression in the dark but has no cumulative effect combined with light. After light exposition, zper2 expression was 2.7 fold increased threefold in the hsf1-morphants in comparison to control embryos. Our results show that zHsf1 plays a positive role in HS-driven expression of zper2 in the dark but seems to act as an attenuator in the presence light.

Circadian modification network of a core clock driver BMAL1 to harmonize physiology from brain to peripheral tissues

Circadian clocks dictate various physiological functions by brain SCN (a central clock) -orchestrating the temporal harmony of peripheral clocks of tissues/organs in the whole body, with adaptability to environments by resetting their timings. Dysfunction of this circadian adaptation system (CAS) occasionally causes/exacerbates diseases. CAS is based on cell-autonomous molecular clocks, which oscillate via a core transcriptional/translational feedback loop with clock genes/proteins, e.g., BMAL1: CLOCK circadian transcription driver and CRY1/2 and PER1/2 suppressors, and is modulated by various regulatory loops including clock protein modifications. Among mutants with a single clock gene, BMAL1-deficient mice exhibit the most drastic loss of circadian functions. Here, we highlight on numerous circadian protein modifications of mammalian BMAL1, e.g., multiple phosphorylations, SUMOylation, ubiquitination, acetylation, O-GlcNAcylation and S-nitrosylation, which mutually interplay to control molecular clocks and coordinate physiological functions from the brain to peripheral tissues through the input and output of the clocks.

The flexible clock: predictive and reactive homeostasis, energy balance and the circadian regulation of sleep–wake timing

The Darwinian fitness of mammals living in a rhythmic environment depends on endogenous daily (circadian) rhythms in behavior and physiology. Here, we discuss the mechanisms underlying the circadian regulation of physiology and behavior in mammals. We also review recent efforts to understand circadian flexibility, such as how the phase of activity and rest is altered depending on the encountered environment. We explain why shifting activity to the day is an adaptive strategy to cope with energetic challenges and show how this can reduce thermoregulatory costs. A framework is provided to make predictions about the optimal timing of activity and rest of non-model species for a wide range of habitats. This Review illustrates how the timing of daily rhythms is reciprocally linked to energy homeostasis, and it highlights the importance of this link in understanding daily rhythms in physiology and behavior.