Evolutionary conservations, changes of circadian rhythms and their effect on circadian disturbances and therapeutic approaches

Impact of food additives on neurodevelopmental processes in zebrafish (Danio rerio): Exploring circadian clock genes and dopamine system

Assessing the impact of food additives on neurodevelopmental processes extends beyond traditional acute toxicity evaluations to address subtler, long-term effects. This study investigates the impact of common food additives (tartrazine, sunset yellow, sodium benzoate, and aspartame) on neurodevelopment in zebrafish embryos, observed from 18 hours postfertilization (hpf) to 91 days postfertilization (dpf). Results show reduced 96 hpf locomotor activity after aspartame exposure, with elevated additives correlating with decreased heart rates and induced neurodegenerative phenotypes, including bent tails and abnormal pigmentation. Although locomotor activity decreases at 7 days postexposure, a gradual recovery is observed. Transcriptome analysis indicates alterations in clock genes (Cry2 and Per2) and dopamine-related genes (NURR1 and tyrosine hydroxylase) in zebrafish larvae. Dietary additive exposure during embryonic development impacts clock genes, influencing dopamine activity and resulting in neurobehavioral changes. This study underscores potential risks associated with dietary additive exposure during critical developmental stages, warranting reconsideration of consumption guidelines, especially for expectant mothers. Observed neurodevelopmental toxicity, even below recommended levels, emphasizes the importance of safeguarding neurodevelopmental health in early life. Our findings contribute to understanding the neurotoxic effects of dietary additives, emphasizing the necessity of protecting neurodevelopment during vulnerable periods. This study is the first to demonstrate a direct correlation between food additives and the dysregulation of key circadian rhythm and dopaminergic genes in zebrafish, providing new insights into the neurodevelopmental impacts of dietary additives. These findings pave the way for further research into the molecular mechanisms and potential implications for human health.

BMAL1 Regulates Glucokinase Expression Through E-Box Elements In Vitro

The organization of a circadian system includes an endogenous pacemaker system, input pathways for environmental synchronizing (entraining) stimuli, and output pathways through which the clock regulates physiological and behavioral processes, for example, the glucose-sensing mechanism in the liver. The liver is the central regulator of metabolism and one of our peripherals clocks. In mammals, central to this pacemaker are the transcription factors Circadian Locomotor Output Cycles Kaput (CLOCK) and BMAL1 (Brain and Muscle ARNT-Like 1). BMAL1 dimerizes with CLOCK, and this heterodimer then binds to the E-box promoter elements (CACGTG) present in clock and clock-controlled genes (CCGs). However, we are just beginning to understand how output pathways and regulatory mechanisms of CCGs are involved in rhythmic physiological processes. Glucokinase (GCK) is a fundamental enzyme in glucose homeostasis, catalyzing the high Km phosphorylation of glucose and allowing its storage. Moreover, gck is a dependent circadian gene. This study aims to determine the contribution of clock genes to hepatic gck expression and to define the specific role of E-box sequences on the circadian regulation of hepatic gck. Results showed that gck expression follows a circadian rhythm in rat hepatocytes in vitro. Accordingly, bmal1 expression induces the glucokinase circadian rhythmic expression in hepatocytes and the analysis of human and rat gck promoters, indicating the presence of E-box regions. Moreover, the basal activity of gck promoter was increased by clock/bmal1 co-transfection but inhibited by Period1/Period2 (per1/per2) co-transfection. Thus, the data suggest that the clock proteins tightly regulate the transcriptional activity of the gck promoter.

Expression profile of circular RNAs in continuous light-induced ovarian dysfunction

PURPOSE

This study aims to elucidate the underlying relationship between the expression profiles of circular RNAs (circRNAs) and the ovarian dysfunction induced by continuous light.

METHODS

High-throughput sequencing was used to profile the transcriptome of differentially expressed circRNAs (DEcircRNAs) in rat ovary under continuous light exposure (12 h:12 h light/light cycle, L/L group) and a control cycle (12 h:12 h light/dark cycle, L/D group). Gene ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and circRNAs-microRNAs-messenger RNAs networks were performed to predict the role of DEcircRNAs in biological processes and pathways. A quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) assay was conducted to verify the high-throughput sequencing results and the expression level of circadian rhythm genes.

RESULTS

In total, 305 circRNAs were differentially expressed between the L/L and L/D groups. Among these, 211 circRNAs were up regulated, while 94 were down regulated. Eight candidate circRNAs from 305 DEcircRNAs were verified by qRT-PCR. Further bioinformatics analysis revealed that interactions between DEcircRNAs and a set of microRNAs involved in ovarian dysfunction-related pathways, such as regulation of androgen receptors, gonadotrophin releasing hormone signaling pathway, endocrine resistance, etc. Subsequently, we identified rno_circ:chr2:86868285-86964272 and rno_circ:chr1:62330221-62360073 may participate in the pathophysiology of ovarian dysfunction by constructing circRNAs-microRNAs-messenger RNAs networks. Meanwhile, constant light reduced the expression of circadian rhythm genes CLOCK, BAML1, PER1, and PER2 compared with that of controls. Caspase3 and Bax were up regulated in the L/L group compared with the L/D group, while Bcl-2 was down regulated.

CONCLUSIONS

In summary, the results reveal that the expression profiles and potential functions of DEcircRNAs in rat ovaries may play important roles in continuous light-induced ovarian dysfunction. These findings provide novel clues and molecular targets for studying the mechanisms and clinical therapy of ovarian dysfunction.

Identification of potential target genes in Homo sapiens, by miRNA of Triticum aestivum: A cross kingdom computational approach

Plant-derived miRNAs can be found in the human body after dietary intake, and they can affect post-transcriptional gene regulation in human. It is important to identify targets to determine the possible effects in human genes by using computational approach. In this study, 787 possible mRNAs human targets were predicted by 84 miRNAs of wheat. A total of 14 miRNAs were identified with individual binding to 33 mRNAs associated with schizophrenia, epilepsy, neurodevelopmental disorders, and various cancers, located in the 3′UTR of the mRNA. A functional enrichment was carried out, where the results showed associations to pathways such as dopaminergic synapse (hsa04728), and signaling pathways, significantly associated with the target genes. The prediction of target mRNAs in humans by wheat miRNAs, offer candidates that could facilitate the search and verification, which could be of relevance for future projects and therefor contribute in the therapeutic treatment of various human diseases.

Polycystic Ovary Syndrome: An Evolutionary Adaptation to Lifestyle and the Environment

Polycystic ovary syndrome (PCOS) is increasingly recognized as a complex metabolic disorder that manifests in genetically susceptible women following a range of negative exposures to nutritional and environmental factors related to contemporary lifestyle. The hypothesis that PCOS phenotypes are derived from a mismatch between ancient genetic survival mechanisms and modern lifestyle practices is supported by a diversity of research findings. The proposed evolutionary model of the pathogenesis of PCOS incorporates evidence related to evolutionary theory, genetic studies, in utero developmental epigenetic programming, transgenerational inheritance, metabolic features including insulin resistance, obesity and the apparent paradox of lean phenotypes, reproductive effects and subfertility, the impact of the microbiome and dysbiosis, endocrine-disrupting chemical exposure, and the influence of lifestyle factors such as poor-quality diet and physical inactivity. Based on these premises, the diverse lines of research are synthesized into a composite evolutionary model of the pathogenesis of PCOS. It is hoped that this model will assist clinicians and patients to understand the importance of lifestyle interventions in the prevention and management of PCOS and provide a conceptual framework for future research. It is appreciated that this theory represents a synthesis of the current evidence and that it is expected to evolve and change over time.

Cognitive functions and underlying parameters of human brain physiology are associated with chronotype

Circadian rhythms have natural relative variations among humans known as chronotype. Chronotype or being a morning or evening person, has a specific physiological, behavioural, and also genetic manifestation. Whether and how chronotype modulates human brain physiology and cognition is, however, not well understood. Here we examine how cortical excitability, neuroplasticity, and cognition are associated with chronotype in early and late chronotype individuals. We monitor motor cortical excitability, brain stimulation-induced neuroplasticity, and examine motor learning and cognitive functions at circadian-preferred and non-preferred times of day in 32 individuals. Motor learning and cognitive performance (working memory, and attention) along with their electrophysiological components are significantly enhanced at the circadian-preferred, compared to the non-preferred time. This outperformance is associated with enhanced cortical excitability (prominent cortical facilitation, diminished cortical inhibition), and long-term potentiation/depression-like plasticity. Our data show convergent findings of how chronotype can modulate human brain functions from basic physiological mechanisms to behaviour and higher-order cognition.