Role of miR-142-3p in the post-transcriptional regulation of the clock gene Bmal1 in the mouse SCN

Micromanaging the neuroendocrine system - A review on miR-7 and the other physiologically relevant miRNAs in the hypothalamic-pituitary axis

The hypothalamic-pituitary axis is central to the functioning of the neuroendocrine system and essential for regulating physiological and behavioral homeostasis and coordinating fundamental body functions. The expanding line of evidence shows the indispensable role of the microRNA pathway in regulating the gene expression profile in the developing and adult hypothalamus and pituitary gland. Experiments provoking a depletion of miRNA maturation in the context of the hypothalamic-pituitary axis brought into focus a prominent involvement of miRNAs in neuroendocrine functions. There are also a few individual miRNAs and miRNA families that have been studied in depth revealing their crucial role in mediating the regulation of fundamental processes such as temporal precision of puberty timing, hormone production, fertility and reproduction capacity, and energy balance. Among these miRNAs, miR-7 was shown to be hypothalamus-enriched and the top one highly expressed in the pituitary gland, where it has a profound impact on gene expression regulation. Here, we review miRNA profiles, knockout phenotypes, and miRNA interaction (targets) in the hypothalamic-pituitary axis that advance our understanding of the roles of miRNAs in mammalian neurosecretion and related physiology.

Impact of Long-Lasting Environmental Factors on Regulation Mediated by the miR-34 Family

The present review focuses on the interactions of newly emerging environmental factors with miRNA-mediated regulation. In particular, we draw attention to the effects of phthalates, electromagnetic fields (EMFs) and a disrupted light/dark cycle. miRNAs are small non-coding RNA molecules with a tremendous regulatory impact, which is usually executed via gene expression inhibition. To address the capacity of environmental factors to influence miRNA-mediated regulation, the miR-34 family was selected for its well-described oncostatic and neuro-modulatory properties. The expression of miR-34 is in a tissue-dependent manner to some extent under the control of the circadian system. There is experimental evidence implicating that phthalates, EMFs and the circadian system interact with the miR-34 family, in both lines of its physiological functioning. The inhibition of miR-34 expression in response to phthalates, EMFs and light contamination has been described in cancer tissue and cell lines and was associated with a decline in oncostatic miR-34a signalling (decrease in p21 expression) and a promotion of tumorigenesis (increases in Noth1, cyclin D1 and cry1 expressions). The effects of miR-34 on neural functions have also been influenced by phthalates, EMFs and a disrupted light/dark cycle. Environmental factors shifted the effects of miR-34 from beneficial to the promotion of neurodegeneration and decreased cognition. Moreover, the apoptogenic capacity of miR-34 induced via phthalate administration in the testes has been shown to negatively influence germ cell proliferation. To conclude, as the oncostatic and positive neuromodulatory functions of the miR-34 family can be strongly influenced by environmental factors, their interactions should be taken into consideration in translational medicine.

Circadian-Coupled Genes Expression and Regulation in HIV-Associated Chronic Obstructive Pulmonary Disease (COPD) and Lung Comorbidities

People living with HIV (PLWH) have an elevated risk of chronic obstructive pulmonary disease (COPD) and are at a higher risk of asthma and worse outcomes. Even though the combination of antiretroviral therapy (cART) has significantly improved the life expectancy of HIV-infected patients, it still shows a higher incidence of COPD in patients as young as 40 years old. Circadian rhythms are endogenous 24 h oscillations that regulate physiological processes, including immune responses. Additionally, they play a significant role in health and diseases by regulating viral replication and its corresponding immune responses. Circadian genes play an essential role in lung pathology, especially in PLWH. The dysregulation of core clock and clock output genes plays an important role in chronic inflammation and aberrant peripheral circadian rhythmicity, particularly in PLWH. In this review, we explained the mechanism underlying circadian clock dysregulation in HIV and its effects on the development and progression of COPD. Furthermore, we discussed potential therapeutic approaches to reset the peripheral molecular clocks and mitigate airway inflammation.

Deciphering clock genes as emerging targets against aging

The old people often suffer from circadian rhythm disturbances, which in turn accelerate aging. Many aging-related degenerative diseases such as Alzheimer's disease, Parkinson's disease, and osteoarthritis have an inextricable connection with circadian rhythm. In light of the predominant effects of clock genes on regulating circadian rhythm, we systematically present the elaborate network of roles that clock genes play in aging in this review. First, we briefly introduce the basic background regarding clock genes. Second, we systemically summarize the roles of clock genes in aging and aging-related degenerative diseases. Third, we discuss the relationship between clock genes polymorphisms and aging. In summary, this review is intended to clarify the indispensable roles of clock genes in aging and sheds light on developing clock genes as anti-aging targets.

Circadian miR-218-5p targets gene CA2 to regulate uterine carbonic anhydrase activity during egg shell calcification

MicroRNAs (miRNAs) are involved in regulating the circadian clock. In our previous work, miR-218-5p was found to be a circadian miRNA in the chicken uterus, but its role in the eggshell formation process was not clear. In the present study, we found that the expression levels of miR-218-5p and two 2 predicted target genes carbonic anhydrase 2 (CA2) and neuronal PAS domain protein 2 (NPAS2) were oscillated in the chicken uterus. The results of dual-luciferase reporter gene assays in the present study demonstrated that miR-218-5p directly targeted the 3' untranslated regions of CA2 and NPAS2. miR-218-5p showed an opposite expression profile to CA2 within a 24 h cycle in the chicken uterus. Moreover, over-expression of miR-218-5p reduced the mRNA and protein expression of CA2, while miR-218-5p knockdown increased CA2 mRNA and protein expression. Overexpression of CA2 also significantly increased the activity of carbonic anhydrase Ⅱ (P < 0.05), whereas knockdown of CA2 decreased the activity of carbonic anhydrase Ⅱ. miR-218-5p influenced carbonic anhydrase activity via regulating the expression of CA2. These results demonstrated that clock-controlled miR-218-5p regulates carbonic anhydrase activity in the chicken uterus by targeting CA2 during eggshell formation.

2.4 GHz Electromagnetic Field Influences the Response of the Circadian Oscillator in the Colorectal Cancer Cell Line DLD1 to miR-34a-Mediated Regulation

Radiofrequency electromagnetic fields (RF-EMF) exert pleiotropic effects on biological processes including circadian rhythms. miR-34a is a small non-coding RNA whose expression is modulated by RF-EMF and has the capacity to regulate clock gene expression. However, interference between RF-EMF and miR-34a-mediated regulation of the circadian oscillator has not yet been elucidated. Therefore, the present study was designed to reveal if 24 h exposure to 2.4 GHz RF-EMF influences miR-34a-induced changes in clock gene expression, migration and proliferation in colorectal cancer cell line DLD1. The effect of up- or downregulation of miR-34a on DLD1 cells was evaluated using real-time PCR, the scratch assay test and the MTS test. Administration of miR-34a decreased the expression of per2, bmal1, sirtuin1 and survivin and inhibited proliferation and migration of DLD1 cells. When miR-34a-transfected DLD1 cells were exposed to 2.4 GHz RF-EMF, an increase in cry1 mRNA expression was observed. The inhibitory effect of miR-34a on per2 and survivin was weakened and abolished, respectively. The effect of miR-34a on proliferation and migration was eliminated by RF-EMF exposure. In conclusion, RF-EMF strongly influenced regulation mediated by the tumour suppressor miR-34a on the peripheral circadian oscillator in DLD1 cells.

A time to heal: microRNA and circadian dynamics in cutaneous wound repair

Many biological systems have evolved circadian rhythms based on the daily cycles of daylight and darkness on Earth. Such rhythms are synchronised or entrained to 24-h cycles, predominantly by light, and disruption of the normal circadian rhythms has been linked to elevation of multiple health risks. The skin serves as a protective barrier to prevent microbial infection and maintain homoeostasis of the underlying tissue and the whole organism. However, in chronic non-healing wounds such as diabetic foot ulcers (DFUs), pressure sores, venous and arterial ulcers, a variety of factors conspire to prevent wound repair. On the other hand, keloids and hypertrophic scars arise from overactive repair mechanisms that fail to cease in a timely fashion, leading to excessive production of extracellular matrix (ECM) components such as such as collagen. Recent years have seen huge increases in our understanding of the functions of microRNAs (miRNAs) in wound repair. Concomitantly, there has been growing recognition of miRNA roles in circadian processes, either as regulators or targets of clock activity or direct responders to external circadian stimuli. In addition, miRNAs are now known to function as intercellular signalling mediators through extracellular vesicles (EVs). In this review, we explore the intersection of mechanisms by which circadian and miRNA responses interact with each other in relation to wound repair in the skin, using keratinocytes, macrophages and fibroblasts as exemplars. We highlight areas for further investigation to support the development of translational insights to support circadian medicine in the context of these cells.

An Overview of Epigenetics in Obesity: The Role of Lifestyle and Therapeutic Interventions

Obesity has become a global epidemic that has a negative impact on population health and the economy of nations. Genetic predispositions have been demonstrated to have a substantial role in the unbalanced energy metabolism seen in obesity. However, these genetic variations cannot entirely explain the massive growth in obesity over the last few decades. Accumulating evidence suggests that modern lifestyle characteristics such as the intake of energy-dense foods, adopting sedentary behavior, or exposure to environmental factors such as industrial endocrine disruptors all contribute to the rising obesity epidemic. Recent advances in the study of DNA and its alterations have considerably increased our understanding of the function of epigenetics in regulating energy metabolism and expenditure in obesity and metabolic diseases. These epigenetic modifications influence how DNA is transcribed without altering its sequence. They are dynamic, reflecting the interplay between the body and its surroundings. Notably, these epigenetic changes are reversible, making them appealing targets for therapeutic and corrective interventions. In this review, I discuss how these epigenetic modifications contribute to the disordered energy metabolism in obesity and to what degree lifestyle and weight reduction strategies and pharmacological drugs can restore energy balance by restoring normal epigenetic profiles.

Exogenous melatonin protects preimplantation embryo development from decabromodiphenyl ethane-induced circadian rhythm disorder and endogenous melatonin reduction

Decabromodiphenyl ethane (DBDPE) is a novel flame retardant that is widely used in plastics, electronic products, building materials and textiles. Our previous studies have revealed the oocyte toxicity of DBDPE, but the effect of DBDPE on preimplantation embryo development has not been reported. Here, we investigated whether and how DBDPE exposure affects preimplantation embryo development. Adult female mice were orally exposed to DBDPE (0, 5, 50, 500 μg/kg bw/day) for 14 days. First, we found that after DBDPE exposure, mice showed obvious circadian rhythm disorder. Moreover, the development of preimplantation embryos was inhibited in DBDPE-exposed mice after pregnancy. Then, we further explored and revealed that DBDPE exposure reduced the endogenous melatonin (MLT) level during pregnancy, thereby inhibiting the development of preimplantation embryos. Furthermore, we discovered that exogenous MLT supplementation (15 mg/kg bw/day) rescued the inhibition of preimplantation embryo development induced by DBDPE, and a mechanistic study demonstrated that exogenous MLT inhibited the overexpression of ROS and DNA methylation at the 5-position of cytosine (5-mC) in DBDPE-exposed preimplantation embryos. Simultaneously, MLT ameliorated the DBDPE-induced mitochondrial dysfunction by increasing the mitochondrial membrane potential (MMP), ATP, and Trp1 expression. Additionally, MLT restored DBDPE-induced changes in zona pellucida (ZP) hardness and trophectoderm (TE) cortical tension. Finally, the protective effect of MLT on embryos ameliorated the adverse reproductive outcomes (dead fetus, fetus with abnormal liver, fetal weight loss) induced by DBDPE. Collectively, DBDPE induced preimplantation embryo damage leading to adverse reproductive outcomes, and MLT has emerged as a potential tool to rescue adverse reproductive outcomes induced by DBDPE.

Mechanisms Driving Palmitate-Mediated Neuronal Dysregulation in the Hypothalamus

The hypothalamus maintains whole-body homeostasis by integrating information from circulating hormones, nutrients and signaling molecules. Distinct neuronal subpopulations that express and secrete unique neuropeptides execute the individual functions of the hypothalamus, including, but not limited to, the regulation of energy homeostasis, reproduction and circadian rhythms. Alterations at the hypothalamic level can lead to a myriad of diseases, such as type 2 diabetes mellitus, obesity, and infertility. The excessive consumption of saturated fatty acids can induce neuroinflammation, endoplasmic reticulum stress, and resistance to peripheral signals, ultimately leading to hyperphagia, obesity, impaired reproductive function and disturbed circadian rhythms. This review focuses on the how the changes in the underlying molecular mechanisms caused by palmitate exposure, the most commonly consumed saturated fatty acid, and the potential involvement of microRNAs, a class of non-coding RNA molecules that regulate gene expression post-transcriptionally, can result in detrimental alterations in protein expression and content. Studying the involvement of microRNAs in hypothalamic function holds immense potential, as these molecular markers are quickly proving to be valuable tools in the diagnosis and treatment of metabolic disease.

MicroRNAs as Potential Orchestrators of Alzheimer's Disease-Related Pathologies: Insights on Current Status and Future Possibilities

Alzheimer's disease (AD) is a progressive and deleterious neurodegenerative disease, strongly affecting the cognitive functions and memory of seniors worldwide. Around 58% of the affected patients live in low and middle-income countries, with estimates of increasing deaths caused by AD in the coming decade. AD is a multifactor pathology. Mitochondrial function declines in AD brain and is currently emerging as a hallmark of this disease. It has been considered as one of the intracellular processes severely compromised in AD. Many mitochondrial parameters decline already during aging; mitochondrial efficiency for energy production, reactive oxygen species (ROS) metabolism and the de novo synthesis of pyrimidines, to reach an extensive functional failure, concomitant with the onset of neurodegenerative conditions. Besides its impact on cognitive functions, AD is characterized by loss of synapses, extracellular amyloid plaques composed of the amyloid-β peptide (Aβ), and intracellular aggregates of hyperphosphorylated Tau protein, accompanied by drastic sleep disorders, sensory function alterations and pain sensitization. Unfortunately, till date, effective management of AD-related disorders and early, non-invasive AD diagnostic markers are yet to be found. MicroRNAs (miRNAs) are small non-coding nucleic acids that regulate key signaling pathway(s) in various disease conditions. About 70% of experimentally detectable miRNAs are expressed in the brain where they regulate neurite outgrowth, dendritic spine morphology, and synaptic plasticity. Increasing studies suggest that miRNAs are intimately involved in synaptic function and specific signals during memory formation. This has been the pivotal key for considering miRNAs crucial molecules to be studied in AD. MicroRNAs dysfunctions are increasingly acknowledged as a pivotal contributor in AD via deregulating genes involved in AD pathogenesis. Moreover, miRNAs have been proved to control pain sensitization processes and regulate circadian clock system that affects the sleep process. Interestingly, the differential expression of miRNA panels implies their emerging potential as diagnostic AD biomarkers. In this review, we will present an updated analysis of miRNAs role in regulating signaling processes that are involved in AD-related pathologies. We will discuss the current challenges against wider use of miRNAs and the future promising capabilities of miRNAs as diagnostic and therapeutic means for better management of AD.

Post-transcriptional modulators and mediators of the circadian clock

The endogenous circadian timekeeping system drives ~24-h rhythms in gene expression and rhythmically coordinates the physiology, metabolism and behavior in a wide range of organisms. Regulation at various levels is important for the accurate functioning of this circadian timing system. The core circadian oscillator consists of an interlocked transcriptional-translational negative feedback loop (TTFL) that imposes a substantial delay between the accumulation of clock gene mRNA and its protein to generate 24-h oscillations. This TTFL mediated daily oscillation of clock proteins is further fine-tuned by post-translational modifications that regulate the clock protein stability, interaction with other proteins and subcellular localization. Emerging evidence from various studies indicates that besides TTFL and post-translational modifications, post-transcriptional regulation plays a key role in shaping the rhythmicity of mRNAs and to delay the accumulation of clock proteins in relation to their mRNAs. In this review, we summarize the current knowledge on the importance of post-transcriptional regulatory mechanisms such as splicing, polyadenylation, the role of RNA-binding proteins, RNA methylation and microRNAs in the context of shaping the circadian rhythmicity in Drosophila and mammals. In particular, we discuss microRNAs, an important player in post-transcriptional regulation of core-clock machinery, circadian neural circuit, clock input, and output pathways. Furthermore, we provide an overview of the microRNAs that exhibit diurnal rhythm in expression and their role in mediating rhythmic physiological processes.

A genome-wide microRNA screen identifies the microRNA-183/96/182 cluster as a modulator of circadian rhythms

The regulatory mechanisms of circadian rhythms have been studied primarily at the level of the transcription-translation feedback loops of protein-coding genes. Regulatory modules involving noncoding RNAs are less thoroughly understood. In particular, emerging evidence has revealed the important role of microRNAs (miRNAs) in maintaining the robustness of the circadian system. To identify miRNAs that have the potential to modulate circadian rhythms, we conducted a genome-wide miRNA screen using U2OS luciferase reporter cells. Among 989 miRNAs in the library, 120 changed the period length in a dose-dependent manner. We further validated the circadian regulatory function of an miRNA cluster, miR-183/96/182, both in vitro and in vivo. We found that all three members of this miRNA cluster can modulate circadian rhythms. Particularly, miR-96 directly targeted a core circadian clock gene, PER2. The knockout of the miR-183/96/182 cluster in mice showed tissue-specific effects on circadian parameters and altered circadian rhythms at the behavioral level. This study identified a large number of miRNAs, including the miR-183/96/182 cluster, as circadian modulators. We provide a resource for further understanding the role of miRNAs in the circadian network and highlight the importance of miRNAs as a genome-wide layer of circadian clock regulation.

Micro RNAs and the biological clock: a target for diseases associated with a loss of circadian regulation

Background

Circadian clocks are self-sustaining oscillators that coordinate behavior and physiology over a 24 hour period, achieving time-dependent homeostasis with the external environment. The molecular clocks driving circadian rhythmic changes are based on intertwined transcriptional/translational feedback loops that combine with a range of environmental and metabolic stimuli to generate daily internal programing. Understanding how biological rhythms are generated throughout the body and the reasons for their dysregulation can provide avenues for temporally directed therapeutics.

Summary

In recent years, microRNAs have been shown to play important roles in the regulation of the circadian clock, particularly in Drosophila, but also in some small animal and human studies. This review will summarize our current understanding of the role of miRNAs during clock regulation, with a particular focus on the control of clock regulated gene expression.

MicroRNA: A Key Player for the Interplay of Circadian Rhythm Abnormalities, Sleep Disorders and Neurodegenerative Diseases

Circadian rhythms are endogenous 24-h oscillators that regulate the sleep/wake cycles and the timing of biological systems to optimize physiology and behavior for the environmental day/night cycles. The systems are basically generated by transcription-translation feedback loops combined with post-transcriptional and post-translational modification. Recently, evidence is emerging that additional non-coding RNA-based mechanisms are also required to maintain proper clock function. MicroRNA is an especially important factor that plays critical roles in regulating circadian rhythm as well as many other physiological functions. Circadian misalignment not only disturbs the sleep/wake cycle and rhythmic physiological activity but also contributes to the development of various diseases, such as sleep disorders and neurodegenerative diseases. The patient with neurodegenerative diseases often experiences profound disruptions in their circadian rhythms and/or sleep/wake cycles. In addition, a growing body of recent evidence implicates sleep disorders as an early symptom of neurodegenerative diseases, and also suggests that abnormalities in the circadian system lead to the onset and expression of neurodegenerative diseases. The genetic mutations which cause the pathogenesis of familial neurodegenerative diseases have been well studied; however, with the exception of Huntington's disease, the majority of neurodegenerative diseases are sporadic. Interestingly, the dysfunction of microRNA is increasingly recognized as a cause of sporadic neurodegenerative diseases through the deregulated genes related to the pathogenesis of neurodegenerative disease, some of which are the causative genes of familial neurodegenerative diseases. Here we review the interplay of circadian rhythm disruption, sleep disorders and neurodegenerative disease, and its relation to microRNA, a key regulator of cellular processes.

Role of Non-Coding RNAs in Lung Circadian Clock Related Diseases

Circadian oscillations are regulated at both central and peripheral levels to maintain physiological homeostasis. The central circadian clock consists of a central pacemaker in the suprachiasmatic nucleus that is entrained by light dark cycles and this, in turn, synchronizes the peripheral clock inherent in other organs. Circadian dysregulation has been attributed to dysregulation of peripheral clock and also associated with several diseases. Components of the molecular clock are disrupted in lung diseases like chronic obstructive pulmonary disease (COPD), asthma and IPF. Airway epithelial cells play an important role in temporally organizing magnitude of immune response, DNA damage response and acute airway inflammation. Non-coding RNAs play an important role in regulation of molecular clock and in turn are also regulated by clock components. Dysregulation of these non-coding RNAs have been shown to impact the expression of core clock genes as well as clock output genes in many organs. However, no studies have currently looked at the potential impact of these non-coding RNAs on lung molecular clock. This review focuses on the ways how these non-coding RNAs regulate and in turn are regulated by the lung molecular clock and its potential impact on lung diseases.

Serum miRNA as a possible biomarker in the diagnosis of bipolar II disorder

The diagnosis of Bipolar II disorder (BD-II) is currently based on the patients' description of symptoms and clinical behavioral observations. This study explored the possibility of miRNA in peripheral blood (serum) as a specific biomarker for BD-II. We identified 6 candidate miRNAs to differentiate BD-II patients from controls using next-generation sequencing. We then examined these candidate miRNAs using real-time PCR in the first cohort (as training group) of 79 BD-II and 95 controls. A diagnostic model was built based on these candidate miRNAs and then tested on an individual testing group (BD-II: n = 20, controls: n = 20). We found that serum expression levels of miR-7-5p, miR-23b-3p, miR-142-3p, miR-221-5p, and miR-370-3p significantly increased in BD-II compared with controls in the first cohort, whereas that of miR-145-5p showed no significant difference. The diagnostic power of the identified miRNAs was further analyzed using receiver-operating characteristic (ROC). Support vector machine (SVM) measurements revealed that a combination of the significant miRNAs reached good diagnostic accuracy (AUC: 0.907). We further examined an independent testing group and the diagnostic power reached fair for BD-II (specificity = 90%, sensitivity = 85%). We constructed miRNA panels using SVM model, which may aid in the diagnosis for BD-II.

MicroRNAs and their regulatory networks in Chinese Gushi chicken abdominal adipose tissue during postnatal late development

Background

Abdominal fat is the major adipose tissue in chickens. The growth status of abdominal fat during postnatal late development ultimately affects meat yield and quality in chickens. MicroRNAs (miRNAs) are endogenous small noncoding RNAs that regulate gene expression at the post-transcriptional level. Studies have shown that miRNAs play an important role in the biological processes involved in adipose tissue development. However, few studies have investigated miRNA expression profiles and their interaction networks associated with the postnatal late development of abdominal adipose tissue in chickens.

Results

We constructed four small RNA libraries from abdominal adipose tissue obtained from Chinese domestic Gushi chickens at 6, 14, 22, and 30 weeks. A total of 507 known miRNAs and 53 novel miRNAs were identified based on the four small RNA libraries. Fifty-one significant differentially expressed (SDE) miRNAs were identified from six combinations by comparative analysis, and the expression patterns of these SDE miRNAs were divided into six subclusters by cluster analysis. Gene ontology enrichment analysis showed that the SDE miRNAs were primarily involved in the regulation of fat cell differentiation, regulation of lipid metabolism, regulation of fatty acid metabolism, and unsaturated fatty acid metabolism in the lipid metabolism- or deposition-related biological process categories. In addition, we constructed differentially expressed miRNA–mRNA interaction networks related to abdominal adipose development. The results showed that miRNA families, such as mir-30, mir-34, mir-199, mir-8, and mir-146, may have key roles in lipid metabolism, adipocyte proliferation and differentiation, and cell junctions during abdominal adipose tissue development in chickens.

Conclusions

This study determined the dynamic miRNA transcriptome and characterized the miRNA–mRNA interaction networks in Gushi chicken abdominal adipose tissue for the first time. The results expanded the number of known miRNAs in abdominal adipose tissue and provide novel insights and a valuable resource to elucidate post-transcriptional regulation mechanisms during postnatal late development of abdominal adipose tissue in chicken.

Network and pathway-based analysis of microRNA role in neuropathic pain in rat models

The molecular mechanisms underlying neuropathic pain (NP) remain poorly understood. Emerging evidence has suggested the role of microRNAs (miRNAs) in the initiation and development of NP, but the specific effects of miRNAs in NP are largely unknown. Here, we use network- and pathway-based methods to investigate NP-induced miRNA changes and their biological functions by conducting a systematic search through multiple electronic databases. Thirty-seven articles meet the inclusion criteria. Venn analysis and target gene forecasting are performed and the results indicate that 167 overlapping target genes are co-regulated by five down-regulated miRNAs (rno-miR-183, rno-miR-96, rno-miR-30b, rno-miR-150 and rno-miR-206). Protein-protein interaction network analysis shows that 77 genes exhibit interactions, with cyclic adenosine monophosphate (cAMP)-dependent protein kinase catalytic subunit beta (degree = 11) and cAMP-response element binding protein 1 (degree = 10) having the highest connectivity degree. Gene ontology analysis shows that these target genes are enriched in neuron part, neuron projection, somatodendritic compartment and nervous system development. Moreover, analysis of Kyoto Encyclopedia of Genes and Genomes reveals that three pathways, namely, axon guidance, circadian entrainment and insulin secretion, are significantly enriched. In addition, rno-miR-183, rno-miR-96, rno-miR-30b, rno-miR-150 and rno-miR-206 are consistently down-regulated in the NP models, thus constituting the potential biomarkers of this disease. Characterizing these miRNAs and their target genes paves way for their future use in clinical practice.

Chronotypical characteristics and related miR-142-3p levels of children with attention deficit and hyperactivity disorder

To compare children with Attention Deficit and Hyperactivity Disorder (ADHD) and a healthy control group in terms of chronotype characteristics and miRNA-142-3p/miRNA-378 levels. 50 children with ADHD and 44 healthy children were included in the study. Childhood Chronotype Questionnaire was used to identify the chronotype preferences of children. Serum miR-142-3p and miR- 378 levels were determined. Preference for nighttime was higher in children with ADHD. Additionally, a night preference was found to be associated with attention deficit in both groups. While a significant correlation was found between the psychopathology rate in mothers and the presence of ADHD, there was no such correlation in fathers. In the comparison between children with ADHD and the control group, no significant difference was found between miRNA levels. Both the miR-142-3p and miR-378 values of the children with ADHD that have immediate relatives with a psychiatric disorder were lower, compared to control group. We found that shift to night preference in the circadian rhythm was higher and this preference was associated with attention deficit in the children with ADHD. In addition, the presence of psychopathology in the family and the mother's psychopathology affected the miR-142-3p and miR378 levels.

Neuroprotection afforded by circadian regulation of intracellular glutathione levels: A key role for miRNAs

Circadian rhythms are approximately 24-h oscillations of physiological and behavioral processes that allow us to adapt to daily environmental cycles. Like many other biological functions, cellular redox status and antioxidative defense systems display circadian rhythmicity. In the central nervous system (CNS), glutathione (GSH) is a critical antioxidant because the CNS is extremely vulnerable to oxidative stress; oxidative stress, in turn, causes several fatal diseases, including neurodegenerative diseases. It has long been known that GSH level shows circadian rhythm, although the mechanism underlying GSH rhythm production has not been well-studied. Several lines of recent evidence indicate that the expression of antioxidant genes involved in GSH homeostasis as well as circadian clock genes are regulated by post-transcriptional regulator microRNA (miRNA), indicating that miRNA plays a key role in generating GSH rhythm. Interestingly, several reports have shown that alterations of miRNA expression as well as circadian rhythm have been known to link with various diseases related to oxidative stress. A growing body of evidence implicates a strong correlation between antioxidative defense, circadian rhythm and miRNA function, therefore, their dysfunctions could cause numerous diseases. It is hoped that continued elucidation of the antioxidative defense systems controlled by novel miRNA regulation under circadian control will advance the development of therapeutics for the diseases caused by oxidative stress.

Sleep Deprivation and the Epigenome

Sleep deprivation disrupts the lives of millions of people every day and has a profound impact on the molecular biology of the brain. These effects begin as changes within a neuron, at the DNA and RNA level, and result in alterations in neuronal plasticity and dysregulation of many cognitive functions including learning and memory. The epigenome plays a critical role in regulating gene expression in the context of memory storage. In this review article, we begin by describing the effects of epigenetic alterations on the regulation of gene expression, focusing on the most common epigenetic mechanisms: (i) DNA methylation; (ii) histone modifications; and (iii) non-coding RNAs. We then discuss evidence suggesting that sleep loss impacts the epigenome and that these epigenetic alterations might mediate the changes in cognition seen following disruption of sleep. The link between sleep and the epigenome is only beginning to be elucidated, but clear evidence exists that epigenetic alterations occur following sleep deprivation. In the future, these changes to the epigenome could be utilized as biomarkers of sleep loss or as therapeutic targets for sleep-related disorders.

Trichosanthes kirilowii extract enhances repair of UVB radiation‑induced DNA damage by regulating BMAL1 and miR‑142‑3p in human keratinocytes

Ultraviolet B (UVB) radiation induces DNA damage, oxidative stress and inflammation, and suppresses the immune system in the skin, which collectively contribute to skin aging and carcinogenesis. The DNA damage response, including DNA repair, can be regulated by the circadian clock and microRNA (miRNA) expression. The aim of the present study was to evaluate the reparative action of Trichosanthes kirilowii extract (TKE) against UVB irradiation-induced DNA damage in human keratinocytes. TKE demonstrated low cytotoxicity in normal HaCaT keratinocytes at low doses (up to 100 µg/ml). The results of a comet assay revealed that TKE enhanced the repair of UVB-induced DNA damage. TKE significantly upregulated the expression of the core clock protein, brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein-1 (BMAL1), and downregulated the expression of miRNA (miR)-142-3p, as demonstrated using western blotting and the reverse transcription-quantitative polymerase chain reaction. Furthermore, the suppression of miR-142-3p by a specific inhibitor positively correlated with the repair activity. Overall, the data obtained demonstrated that TKE enhanced the repair of UVB-induced DNA damage by regulating the expression of BMAL1 and miR-142-3p. Consequently, TKE can be considered a potential candidate for the treatment of skin diseases associated with UVB-induced damage.

Molecular modulators of the circadian clock: lessons from flies and mice

Circadian timekeeping is a ubiquitous mechanism that enables organisms to maintain temporal coordination between internal biological processes and time of the local environment. The molecular basis of circadian rhythms lies in a set of transcription-translation feedback loops (TTFLs) that drives the rhythmic transcription of core clock genes, whose level and phase of expression serve as the marker of circadian time. However, it has become increasingly evident that additional regulatory mechanisms impinge upon the TTFLs to govern the properties and behavior of the circadian clock. Such mechanisms include changes in chromatin architecture, interactions with other transcription factor networks, post-transcriptional control by RNA modifications, alternative splicing and microRNAs, and post-translational regulation of subcellular trafficking and protein degradation. In this review, we will summarize the current knowledge of circadian clock regulation-from transcriptional to post-translational-drawing from literature pertaining to the Drosophila and murine circadian systems.

Systems Biology-Derived Discoveries of Intrinsic Clocks

A systems approach to studying biology uses a variety of mathematical, computational, and engineering tools to holistically understand and model properties of cells, tissues, and organisms. Building from early biochemical, genetic, and physiological studies, systems biology became established through the development of genome-wide methods, high-throughput procedures, modern computational processing power, and bioinformatics. Here, we highlight a variety of systems approaches to the study of biological rhythms that occur with a 24-h period-circadian rhythms. We review how systems methods have helped to elucidate complex behaviors of the circadian clock including temperature compensation, rhythmicity, and robustness. Finally, we explain the contribution of systems biology to the transcription-translation feedback loop and posttranslational oscillator models of circadian rhythms and describe new technologies and "-omics" approaches to understand circadian timekeeping and neurophysiology.

A novel role of microRNA 17-5p in the modulation of circadian rhythm

The circadian clock helps living organisms to adjust their physiology and behaviour to adapt environmental day-night cycles. The period length of circadian rhythm reflects the endogenous cycle transition rate and is modulated by environmental cues or internal molecules, and the latter are of substantial importance but remain poorly revealed. Here, we demonstrated that microRNA 17-5p (miR-17-5p), which has been associated with tumours, was an important factor in controlling the circadian period. MiR-17-5p was rhythmically expressed in synchronised fibroblasts and mouse master clock suprachiasmatic nuclei (SCN). MiR-17-5p and the gene Clock exhibited a reciprocal regulation: miR-17-5p inhibited the translation of Clock by targeting the 3′UTR (untranslated region) of Clock mRNA, whereas the CLOCK protein directly bound to the promoter of miR-17 and enhanced its transcription and production of miR-17-5p. In addition, miR-17-5p suppressed the expression of Npas2. At the cellular level, bidirectional changes in miR-17-5p or CLOCK resulted in CRY1 elevation. Accordingly, in vivo, both increase and decrease of miR-17-5p in the mouse SCN led to an increase in CRY1 level and shortening of the free-running period. We conclude that miR-17-5p has an important role in the inspection and stabilisation of the circadian-clock period by interacting with Clock and Npas2 and potentially via the output of CRY1.

Role of Inflammatory Signaling in the Differential Effects of Saturated and Poly-unsaturated Fatty Acids on Peripheral Circadian Clocks

Inflammatory signaling may play a role in high-fat diet (HFD)-related circadian clock disturbances that contribute to systemic metabolic dysregulation. Therefore, palmitate, the prevalent proinflammatory saturated fatty acid (SFA) in HFD and the anti-inflammatory, poly-unsaturated fatty acid (PUFA), docosahexaenoic acid (DHA), were analyzed for effects on circadian timekeeping and inflammatory responses in peripheral clocks. Prolonged palmitate, but not DHA, exposure increased the period of fibroblast Bmal1-dLuc rhythms. Acute palmitate treatment produced phase shifts of the Bmal1-dLuc rhythm that were larger in amplitude as compared to DHA. These phase-shifting effects were time-dependent and contemporaneous with rhythmic changes in palmitate-induced inflammatory responses. Fibroblast and differentiated adipocyte clocks exhibited cell-specific differences in the time-dependent nature of palmitate-induced shifts and inflammation. DHA and other inhibitors of inflammatory signaling (AICAR, cardamonin) repressed palmitate-induced proinflammatory responses and phase shifts of the fibroblast clock, suggesting that SFA-mediated inflammatory signaling may feed back to modulate circadian timekeeping in peripheral clocks.

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The saturated fatty acid (SFA) palmitate differentially modulates the circadian timekeeping mechanism in peripheral clocks;

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Palmitate induces time-dependent phase shifts that coincide with its rhythmic induction of inflammatory signaling;

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Time-dependent nature of the palmitate-induced phase shifts and inflammatory signaling is cell specific;

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Inhibitors of inflammatory signaling repress the proinflammatory and phase shifting effects of palmitate;

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Inflammatory signaling plays a role in the mechanism by which palmitate alters circadian timekeeping in peripheral clocks.

Circadian or 24-hour clocks throughout the body mediate the local temporal coordination of tissue- or cell-specific processes necessary for normal inflammatory responses and metabolic homeostasis. Dysregulation of peripheral clocks and their timekeeping function contribute to obesity-related metabolic disorders (e.g., type 2 diabetes). Our data unveil a novel mechanism by which mutual interactions between peripheral clocks and inflammatory signaling pathways dysregulate circadian timekeeping, and exacerbate proinflammatory responses to saturated fatty acids. These studies will guide the development of chronotherapeutic drug and/or dietary omega-3 fatty acid treatments for managing and preventing metabolic disorders and other inflammation-related pathologies (e.g., cardiovascular disease, stroke, arthritis).

Diagnostic Value of Cell-free Circulating MicroRNAs for Obesity and Type 2 Diabetes: A Meta-analysis

Type 2 diabetes mellitus (T2DM) is the most common metabolic disorder worldwide. Because of population aging and increasing trends toward obesity and sedentary lifestyles, the number of affected individuals is increasing at worrisome rates. While both environmental and genetic factors are known to contribute to the development of T2DM, continuous research is needed to identify specific biomarkers that could aid both in prevention of the disease and development of newer therapeutic options. Circulating miRNAs are considered as potential biomarkers because they are stable and resistant to degradation by blood RNAses and are modified under different pathophysiological conditions. In this study we carried out a systematic electronic search on PubMed to retrieve all articles that have investigated circulating miRNAs for diagnosing obesity andT2DM in human. We also included lifestyle intervention studies known to be highly effective in delaying onset of diabetes, and studies analyzing the effect of bariatric surgery and anti-diabetic treatment. A total of 26 studies were enrolled in the global meta-analysis. Candidate miRNAs were defined as those reported in at least 2 studies with same direction of differential expression. Ten miRNAs altered in blood of patients suffering fromT2DM were identified (increased: miR-320a, miR-142-3p, miR-222, miR-29a, miR-27a, miR-375; decreased: miR-197, miR-20b, miR-17, miR-652) and 7 miRNAs in blood of obese subjects were identified (increased: miR-142-3p, miR-140-5p, miR-222; decreased:miR-21-5p, miR-221-3p, miR-125-5p, mir-103-5p). Both obese and T2DM patients had elevated concentrations of miR-142-3p and miR-222. MiRNAs target genes were predicted and their cellular functions are discussed in relation with the pathologies. Although a significant number of studies were taken into account in this review, we found a strong discrepancy between miRNA detection and quantification indicating that many of pre-analytical variables have yet to be normalized. Pre-analytical and analytical challenges are also discussed.

Noncoding RNAs and neurobehavioral mechanisms in psychiatric disease

The human genome project has revolutionized our understanding of the underlying mechanisms in psychiatric disease. It is now abundantly clear that neurobehavioral phenotypes are epigenetically controlled by noncoding RNAs (ncRNAs). The microRNA (miRNA) class of ncRNAs are ubiquitously expressed throughout the brain and govern all major neuronal pathways. The attractive therapeutic potential of miRNAs is underscored by their pleiotropic capacities, putatively targeting multiple pathways within a single neuron. Many psychiatric diseases stem from a multifactorial origin, thus conventional drug targeting of single proteins may not prove most effective. In this exciting post-genome sequencing era, many new epigenetic targets are emerging for therapeutic investigation. Here we review the reported roles of miRNAs, as well as other ncRNA classes, in the pathology of psychiatric disorders; there are both common and unique ncRNA mechanisms that influence the various diagnoses. Collectively, these potent epigenetic regulators may clarify the disrupted signaling networks in psychiatric phenotypes.

Assembly of a comprehensive regulatory network for the mammalian circadian clock: a bioinformatics approach

By regulating the timing of cellular processes, the circadian clock provides a way to adapt physiology and behaviour to the geophysical time. In mammals, a light-entrainable master clock located in the suprachiasmatic nucleus (SCN) controls peripheral clocks that are present in virtually every body cell. Defective circadian timing is associated with several pathologies such as cancer and metabolic and sleep disorders. To better understand the circadian regulation of cellular processes, we developed a bioinformatics pipeline encompassing the analysis of high-throughput data sets and the exploitation of published knowledge by text-mining. We identified 118 novel potential clock-regulated genes and integrated them into an existing high-quality circadian network, generating the to-date most comprehensive network of circadian regulated genes (NCRG). To validate particular elements in our network, we assessed publicly available ChIP-seq data for BMAL1, REV-ERBα/β and RORα/γ proteins and found strong evidence for circadian regulation of Elavl1, Nme1, Dhx6, Med1 and Rbbp7 all of which are involved in the regulation of tumourigenesis. Furthermore, we identified Ncl and Ddx6, as targets of RORγ and REV-ERBα, β, respectively. Most interestingly, these genes were also reported to be involved in miRNA regulation; in particular, NCL regulates several miRNAs, all involved in cancer aggressiveness. Thus, NCL represents a novel potential link via which the circadian clock, and specifically RORγ, regulates the expression of miRNAs, with particular consequences in breast cancer progression. Our findings bring us one step forward towards a mechanistic understanding of mammalian circadian regulation, and provide further evidence of the influence of circadian deregulation in cancer.

Expression profiling of preadipocyte microRNAs by deep sequencing on chicken lines divergently selected for abdominal fatness

Through posttranscriptional gene regulation, microRNA (miRNA) is linked to a wide variety of biological processes, including adipogenesis and lipid metabolism. Although miRNAs in mammalian adipogenesis have been worked on extensively, their study in chicken adipogenesis is still very limited. To find miRNAs potentially important for chicken preadipocyte development, we compared the preadipocyte miRNA expression profiles in two broiler lines divergently selected for abdominal fat content, by sequencing two small RNA libraries constructed for primary preadipocytes isolated from abdominal adipose tissues. After bioinformatics analyses, from chicken miRNAs deposited in miRBase 20.0, we identified 225 miRNAs to be expressed in preadipocytes, 185 in the lean line and 200 in the fat line (derived from 208 and 203 miRNA precursors, respectively), which corresponds to 114 miRNA families. The let-7 family miRNAs were the most abundant. Furthermore, we validated the sequencing results of 15 known miRNAs by qRT-PCR, and confirmed that the expression levels of most miRNAs correlated well with those of Solexa sequencing. A total of 33 miRNAs was significantly differentially expressed between the two chicken lines (P<0.05). Gene ontology analysis revealed that they could target genes enriched in the regulation of gene transcription and chromatin function, response to insulin stimulation, and IGF-1 signaling pathways, which could have important roles in preadipocyte development. Therefore, a valuable information and resource of miRNAs on chicken adipogenesis were provided in this study. Future functional investigations on these miRNAs could help explore related genes and molecular networks fundamental to preadipocyte development.

Circadian genomics reveal a role for post-transcriptional regulation in mammals

To maintain daily cycles, the circadian clock must tightly regulate the rhythms of thousands of mRNAs and proteins with the correct period, phase, and amplitude to ultimately drive the wide range of rhythmic biological processes. Recent genomic approaches have revolutionized our view of circadian gene expression and highlighted the importance of post-transcriptional regulation in driving mRNA rhythmicity. Even after transcripts are made from DNA, subsequent processing and regulatory steps determine when, where, and how much protein will be generated. These post-transcriptional regulatory mechanisms can add flexibility to overall gene expression and alter protein levels rapidly without requiring transcript synthesis and are therefore beneficial for cells; however, the extent to which circadian post-transcriptional mechanisms contribute to rhythmic profiles throughout the genome and the mechanisms involved have not been fully elucidated. In this review, we will summarize how circadian genomics have revealed new insights into rhythmic post-transcriptional regulation in mammals and discuss potential implications of such regulation in controlling many circadian-driven physiologies.

Regulation of human growth hormone receptor expression by microRNAs

Human GH binds to its receptor (GHR) on target cells and activates multiple intracellular pathways, leading to changes in gene expression, differentiation, and metabolism. GHR deficiency is associated with growth and metabolic disorders whereas increased GHR expression has been reported in certain cancers, suggesting that the GHR gene requires tight controls. Several regulatory mechanisms have been found within its 5'-untranslated region (UTR) promoter and coding regions. However, the 3'-UTR has not been previously examined. MicroRNAs (miRNAs) are small (19-22 nucleotides) noncoding RNAs that downregulate gene expression mainly through targeting the 3'-UTR of mRNAs and enhancing their degradation or inhibiting translation. In the present study, we investigated whether miRNAs regulate GHR expression. To define putative miRNA binding sites in the GHR 3'-UTR, we used multiple in silico prediction tools, analyzed conservation across species and the presence of parallel sites in GH/IGF axis-related genes, and searched for reports linking miRNAs to GHR-related physiological or pathophysiological activities. To test prioritized sites, we cotransfected a wild-type GHR 3'-UTR luciferase reporter vector as well as miRNA binding site mutants into HEK293 cells with miRNA mimics. Furthermore, we tested whether the miRNAs altered endogenous GHR mRNA and protein levels in HEK293 cells and in 2 cancer cell lines (MCF7 and LNCaP). Our experiments have identified miRNA (miR)-129-5p, miR-142-3p, miR-202, and miR-16 as potent inhibitors of human GHR expression in normal (HEK293) and cancer (MCF7 and LNCaP) cells. This study paves the way for the development of miRNA inhibitors as therapeutic agents in GH/GHR-related pathophysiologies, including cancer.

MicroRNAs function as cis- and trans-acting modulators of peripheral circadian clocks

Based on their extracellular expression and targeting of the clock gene Bmal1, miR-142-3p and miR-494 were analyzed for evidence of vesicle-mediated communication between cells and intracellular functional activity. Our studies demonstrate that: miR-142-3p+miR-494 overexpression decreases endogenous BMAL1 levels, increases the period of Per2 oscillations, and increases extracellular miR-142-3p/miR-494 abundance in conditioned medium; miRNA-enriched medium increases intracellular expression of miR-142-3p and represses Bmal1 3'-UTR activity in naïve cells; and inhibitors of vesicular trafficking modulate intercellular communication of these miRNAs and ensemble Per2 rhythms. Thus, miR-142-3p and miR-494 may function as cis- and trans-acting signals contributing to local temporal coordination of cell-autonomous circadian clocks.

MicroRNAs shape circadian hepatic gene expression on a transcriptome-wide scale

A considerable proportion of mammalian gene expression undergoes circadian oscillations. Post-transcriptional mechanisms likely make important contributions to mRNA abundance rhythms. We have investigated how microRNAs (miRNAs) contribute to core clock and clock-controlled gene expression using mice in which miRNA biogenesis can be inactivated in the liver. While the hepatic core clock was surprisingly resilient to miRNA loss, whole transcriptome sequencing uncovered widespread effects on clock output gene expression. Cyclic transcription paired with miRNA-mediated regulation was thus identified as a frequent phenomenon that affected up to 30% of the rhythmic transcriptome and served to post-transcriptionally adjust the phases and amplitudes of rhythmic mRNA accumulation. However, only few mRNA rhythms were actually generated by miRNAs. Overall, our study suggests that miRNAs function to adapt clock-driven gene expression to tissue-specific requirements. Finally, we pinpoint several miRNAs predicted to act as modulators of rhythmic transcripts, and identify rhythmic pathways particularly prone to miRNA regulation.

DOI:http://dx.doi.org/10.7554/eLife.02510.001

The rising and setting of the sun have long driven the schedules of humans and other mammals. This 24-hr cycle influences many behavioural and physiological changes, including alertness, body temperature, and sleep. A region in the brain acts as a master clock that regulates these daily cycles, which are called circadian rhythms.

Signals from the brain's master clock turn on and off ‘core clock genes’ in cells, which trigger cycles that cause some proteins to be produced in a circadian rhythm. The rhythm is specialized to a particular tissue or organ, and may help them to carry out their designated daily tasks. However, circadian rhythms might also be produced in other ways that do not involve these genes.

Messenger RNA (mRNA) molecules have a central role in the production of proteins, and in the mouse liver, up to 15% of mRNA molecules are produced in circadian cycles. The liver performs essential tasks that control metabolism–including that of carbohydrates, fats, and cholesterol. Precisely timing when certain mRNAs and proteins reach peaks and troughs in their activities to coincide with mealtimes is important for nutrients to be properly processed.

Other RNA molecules called microRNAs influence how mRNA molecules are translated into proteins. Now Du, Arpat et al. have looked at the influence of microRNAs on circadian rhythms in the mouse liver in greater detail. These experiments, which involved ‘knocking out’ a gene that is essential for the production of microRNAs, show that rather than setting the mRNA rhythms, the microRNAs appear to adjust them to meet the specific needs of the liver. Targeting specific microRNA molecules may reveal new strategies to tweak these rhythms, which could help to improve conditions when metabolic functions go wrong.

DOI:http://dx.doi.org/10.7554/eLife.02510.002

The effects of the heme precursor 5-aminolevulinic acid (ALA) on REV-ERBα activation

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REV-ERBα has a key role in circadian rhythms and requires heme as its ligand.

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Heme precursor ALA exhibited increased nuclear heme level and activation of REV-ERBα.

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ALA inhibited REV-ERBα target genes including an essential component of the circadian oscillator.

The nuclear receptor, REV-ERBα, has a key role in circadian rhythms and requires heme as its ligand. The present study determined whether the heme precursor, 5-aminolevulinic acid (ALA), affects REV-ERBα and its target genes. When exposed to ALA, the human lung diploid cell line, WI-38, exhibited activation of REV-ERBα and repression of the transcription of REV-ERBα target genes, including BMAL1, an essential component of the circadian oscillator. Moreover, co-incubation of sodium ferrous citrate (SFC) and ALA also activated REV-ERBα and repressed the transcription of REV-ERBα target genes. These results indicate that ALA regulates human circadian rhythms via REV-ERBα.

MicroRNA-142 reduces monoamine oxidase A expression and activity in neuronal cells by downregulating SIRT1

Aberrant expression of microRNAs (miRs) has been implicated in the pathogenesis of several neurodegenerative disorders. In HIV-associated neurocognitive disorders (HAND), miR-142 was found to be upregulated in neurons and myeloid cells in the brain. We investigated the downstream effects of chronic miR-142 upregulation in neuronal cells by comparing gene expression in stable clones of the human neuroblastoma cell line BE(2)M17 expressing miR-142 to controls. Microarray analysis revealed that miR-142 expression led to a reduction in monoamine oxidase (MAO) A mRNA, which was validated by qRT-PCR. In addition to the mRNA, the MAOA protein level and enzyme activity were also reduced. Examination of primary human neurons revealed that miR-142 expression indeed resulted in a downregulation of MAOA protein level. Although MAOA is not a direct target of miR-142, SIRT1, a key transcriptional upregulator of MAOA is, thus miR-142 downregulation of MAOA expression is indirect. MiR-142 induced decrease in MAOA expression and activity may contribute to the changes in dopaminergic neurotransmission reported in HAND.