Analyses of circRNA Expression throughout the Light-Dark Cycle Reveal a Strong Regulation of Cdr1as, Associated with Light Entrainment in the SCN

CircRNA Itm2b induces oxidative stress via the interaction with Sirt1-Nox4 to aggravate sleep disturbances after traumatic brain injury

Sleep disorders (SD) are common sequelae following traumatic brain injury (TBI) and may be linked to mitochondrial oxidative stress dysregulation after TBI. Increasing evidence showed that circRNAs play crucial roles in nervous system diseases. However, the involvement of circRNAs in sleep disturbances after TBI is not characterized. In this study, differentially expressed circRNAs were identified by RNA sequencing. Sleep quality in TBI patients was assessed through sleep scales and electroencephalograms. Further experiments were conducted to investigate the role of circItm2b. We found that circItm2b was elevated and involved sleep disorder in TBI patients. Over-expression of circItm2b might aggravate sleep disturbances in mice after TBI. Mechanically, circItm2b regulates Nox4 expression through binding Sirt1, which influences mitochondrial oxidative stress-caused circadian protein losses. Moreover, the knockdown of circItm2b attenuated mitochondrial oxidative stress-induced circadian proteins losses via circItm2b/Sirt1/Nox4 axis after TBI, which might suggest that circItm2b may serve as a prognostic marker for improving sleep disorders and represent a promising therapeutic target for TBI-related sleep disturbances.

Microglia undergo molecular and functional adaptations to dark and light phases in male laboratory mice

Microglia are increasingly recognized to contribute to brain health and disease. Preclinical studies using laboratory rodents are essential to advance our understanding of the physiological and pathophysiological roles of these cells in the central nervous system. Rodents are nocturnal animals, and they are mostly maintained in a defined light-dark cycle within animal facilities, with many laboratories investigating the molecular and functional profiles of microglia exclusively during the animals' light (sleep) phase. However, only a few studies have considered possible differences in microglial functions between the active and sleep phases. Based on initial evidence suggesting that microglial intrinsic clock genes can affect their phenotypes, we sought to investigate differences in transcriptional, proteotype and functional profiles of microglia between light (sleep) and dark (active) phases, and how these changes are affected in pathological models. We found marked transcriptional and proteotype differences between microglia harvested from male mice during the light or dark phase. Amongst others, these differences related to genes and proteins associated with immune responses, motility, and phagocytosis, which were reflected by functional alterations in microglial synaptic pruning and response to bacterial stimuli. Possibly accounting for such changes, we found RNA and protein regulation in SWI/SNF and NuRD chromatin remodeling complexes between light and dark phases. Importantly, we also show that the time of microglial sample collection influences the nature of microglial transcriptomic changes in a model of immune-mediated neurodevelopmental disorders. Our findings emphasize the importance of considering diurnal factors in studying microglial cells and indicate that implementing a circadian perspective is pivotal for advancing our understanding of their physiological and pathophysiological roles in brain health and disease.

Multiplex influences on vigilance and biochemical variables induced by sleep deprivation

Introduction

Sleep loss and sleep deprivation (SD) cause deleterious influences on health, cognition, mood and behaviour. Nevertheless, insufficient sleep and SD are prevalent across many industries and occur in various emergencies. The deleterious consequences of SD have yet to be fully elucidated. This study aimed to assess the extensive influences of SD on physiology, vigilance, and plasma biochemical variables.

Methods

Seventeen volunteers were recruited to participate in a 32.5-h SD experiment. Multiple physiological and cognitive variables, including tympanic temperature, blood oxygen saturation (SaO2), and vigilance were recorded. Urinal/salivary samples were collected and subjected to cortisol or cortisone analysis, and plasma samples were subjected to transcriptomic analysis of circular RNA (circRNA) expression using microarray. Plasma neurotransmitters were measured by targeted metabolic analysis, and the levels of inflammatory factors were assessed by antibody microarray.

Results

The volunteers showed significantly increased sleepiness and decreased vigilance during SD, and the changes in circadian rhythm and plasma biochemistry were observed. The plasma calcium (p = 0.0007) was induced by SD, while ischaemia-modified albumin (IMA, p = 0.0030) and total bile acid (TBA, p = 0.0157) decreased. Differentially expressed circRNAs in plasma were identified, which are involved in multiple signaling pathways including neuronal regulation and immunity. Accordingly, SD induced a decrease in 3-hydroxybutyric acid (3OBH, p = 0.0002) and an increase in thyroxine (T4, p < 0.0001) in plasma. The plasma anti-inflammatory cytokine IL-10 was downregulated while other ten inflammatory factors were upregulated.

Conclusion

This study demonstrates that SD influences biochemical, physiological, cognitive variables, and the significantly changed variables may serve as candidates of SD markers. These findings may further our understanding of the detrimental consequence of sleep disturbance at multiple levels.

Novel Insights into the Circadian Rhythms Based on Long Noncoding and Circular RNA Profiling

Circadian rhythm disorders pose major risks to human health and animal production activity, and the hypothalamus is the center of circadian rhythm regulation. However, the epigenetic regulation of circadian rhythm based on farm animal models has been poorly investigated. We collected chicken hypothalamus samples at seven time points in one light/dark cycle and performed long noncoding RNA (lncRNA), circular RNA (circRNA), and mRNA sequencing to detect biomarkers associated with circadian rhythm. We enhanced the comprehensive expression profiling of ncRNAs and mRNAs in the hypothalamus and found two gene sets (circadian rhythm and retinal metabolism) associated with the light/dark cycle. Noncoding RNA networks with circadian expression patterns were identified by differential expression and circadian analysis was provided that included 38 lncRNAs, 15 circRNAs, and 200 candidate genes. Three lncRNAs (ENSGALT00000098661, ENSGALT00000100816, and MSTRG.16980.1) and one circRNA (novel_circ_010168) in the ncRNA-mRNA regulatory network were identified as key molecules influencing circadian rhythm by regulating AOX1 in retinal metabolism. These ncRNAs were predicted to be related to pernicious anemia, gonadal, eye disease and other disorders in humans. Together, the findings of this study provide insights into the epigenetic mechanisms of circadian rhythm and reveal AOX1 as a promising target of circadian rhythm regulation.

RNA regulation in brain function and disease 2022 (NeuroRNA): A conference report

Recent research integrates novel technologies and methods from the interface of RNA biology and neuroscience. This advancing integration of both fields creates new opportunities in neuroscience to deepen the understanding of gene expression programs and their regulation that underlies the cellular heterogeneity and physiology of the central nervous system. Currently, transcriptional heterogeneity can be studied in individual neural cell types in health and disease. Furthermore, there is an increasing interest in RNA technologies and their application in neurology. These aspects were discussed at an online conference that was shortly named NeuroRNA.