Activation of CB2R with AM1241 ameliorates neurodegeneration via the Xist/miR-133b-3p/Pitx3 axis

The role of cannabinoid-mediated signaling pathways and mechanisms in brain disorders

Cannabinoids play significant roles in the central nervous system (CNS), but cannabinoid-mediated physiopathological functions are not elaborated. Cannabinoid receptors (CBRs) mediate functions that include the regulation of neuroinflammation, oxidative stress, apoptosis, autophagy, and neurogenesis. Microglia are the primary immune cells responsible for mediating neuroinflammation in the CNS. Therefore, this article primarily focuses on microglia to summarize the inflammatory pathways mediated by cannabinoids in the CNS, including nuclear factor-κB (NF-κB), NOD-like receptor protein 3 (NLRP3) inflammasome, mitogen-activated protein kinase (MAPK), protein kinase B (Akt), and cAMP-dependent protein kinase (PKA) signaling pathways. Additionally, we provide a table summarizing the role of cannabinoids in various brain diseases. Medical use of cannabinoids has protective effects in preventing and treating brain diseases; however, excessive and repeated use can be detrimental to the CNS. We propose that cannabinoids hold significant potential for preventing and treating brain diseases, including ferroptosis, lactate metabolism, and mitophagy, providing new insights for further research on cannabinoids.

Therapeutic potential of EVs loaded with CB2 receptor agonist in spinal cord injury via the Nrf2/HO-1 pathway

BACKGROUND

Spinal cord injury (SCI) poses a challenge due to limited treatment options. Recently, the effect and mechanism of Exo-loaded cannabinoid receptor type 2 (CB2) agonist AM1241(Exo + AM1241) have been applied in other inflammatory diseases but not in SCI.

METHODS

The SCI model was set up using C57BL/6 mice, followed by the treatment of Exo, AM1241, and Exo + AM1241. We assessed the effects of the following treatments on motor function recovery using BMS, and evaluated histological changes, apoptosis activity, inflammation, and oxidative stress in the SCI mice model. Additionally, the effect of following treatments on spinal cord neural stem cells (NSCs) was evaluated under lipopolysaccharides (LPS) induced inflammatory and oxidative models and, glutamate (Gluts) induced cell apoptosis models.

RESULT

Our results demonstrated that Exo + AM1241 treatment significantly improved motor function recovery, after SCI by decreasing proinflammatory cytokines, and suppressing astrocyte/microglia (GFAP/Iba1) activation in the injury zone. Additionally, this treatment reduces pro-apoptotic proteins (Bax and caspase 3), increases the levels of the anti-apoptotic protein Bcl-2, enhances antioxidant defenses by boosting SOD and GSH, and lowers oxidative stress markers such as MDA. It also activates the Nuclear factor erythroid-2 (Nrf2) related factor 2 signaling pathway, thereby enhancing tissue protection against damage and cell death.

JWH133 attenuates behavior deficits and iron accumulation in 6-OHDA-induced Parkinson's disease model rats

Growing evidence indicates that activation of cannabinoid type 2 (CB2) receptors protects dopamine neurons in the pathogenesis of Parkinson's disease (PD). However, the mechanisms underlying neuroprotection mediated by CB2 receptors are still elusive. In this study, we investigated the effects of CB2 receptor activation on 6-hydroxydopamine (6-OHDA)-induced dopamine neuron degeneration and iron accumulation in the substantia nigra (SN) of rats. We found that treatment with JWH133, a selective CB2 receptor agonist, significantly improved the apomorphine (APO)-induced rotational behavior in 6-OHDA-treated rats. The decreased numbers of tyrosine hydroxylase (TH)-positive neurons and reduced TH protein expression in the lesioned SN of rats were effectively restored by JWH133. Moreover, we found that JWH133 inhibited the increase of iron-staining cells in the lesioned SN of rats. To explore the protective mechanisms of activation of CB2 receptors on dopamine neurons, we further observed the effect of JWH133 on 1-methyl-4-phenylpyridinium (MPP+)-treated primary cultured ventral mesencephalon (VM) neurons from rats. We found that JWH133 significantly inhibited the increase of intracellular reactive oxygen species (ROS), the activation of Caspase-3, the decrease of mitochondrial transmembrane potential (ΔΨm), and the decrease of Bcl-2/Bax protein expression caused by MPP+ treatment. JWH133 also inhibited the MPP+-induced upregulation of divalent metal transporter-1 (DMT1) and downregulation of ferroportin 1 (FPN1). Furthermore, JWH133 also suppressed the MPP+-accelerated iron influx in the VM neurons. These results suggest that activation of CB2 receptor suppresses MPP+-induced cellular iron accumulation and prevents neurodegeneration.NEW & NOTEWORTHY Expression of cannabinoid type 2 receptors (CB2Rs) was discovered on dopamine neurons in recent years. The role of CB2R expressed on dopamine neurons in the pathogenesis of Parkinson's disease (PD) has not been fully elucidated. The content of iron accumulation in the brain is closely related to the progress of PD. We verified the inhibitory effect of CB2R on iron deposition in dopamine neurons through experiments, which provided a new idea for the treatment of PD.

Cannabinoid receptor 2 agonist AM1241 alleviates epileptic seizures and epilepsy-associated depression via inhibiting neuroinflammation in a pilocarpine-induced chronic epilepsy mouse model

Increasing evidence suggests that cannabinoid receptor 2 (CB2R) serves as a promising anti-inflammatory target. While inflammation is known to play crucial roles in the pathogenesis of epilepsy, the involvement of CB2R in epilepsy remains unclear. This study aimed to investigate the effects of a CB2R agonist, AM1241, on epileptic seizures and depressive-like behaviors in a mouse model of chronic epilepsy induced by pilocarpine. A chronic epilepsy mouse model was established by intraperitoneal administration of pilocarpine. The endogenous cannabinoid system (eCBs) in the hippocampus was examined after status epilepticus (SE). Animals were then treated with AM1241 and compared with a vehicle-treated control group. Additionally, the role of the AMPK/NLRP3 signaling pathway was explored using the selective AMPK inhibitor dorsomorphin. Following SE, CB2R expression increased significantly in hippocampal microglia. Administration of AM1241 significantly reduced seizure frequency, immobility time in the tail suspension test, and neuronal loss in the hippocampus. In addition, AM1241 treatment attenuated microglial activation, inhibited pro-inflammatory polarization of microglia, and suppressed NLRP3 inflammasome activation in the hippocampus after SE. Further, the therapeutic effects of AM1241 were abolished by the AMPK inhibitor dorsomorphin. Our findings suggest that CB2R agonist AM1241 may alleviate epileptic seizures and its associated depression by inhibiting neuroinflammation through the AMPK/NLRP3 signaling pathway. These results provide insight into a novel therapeutic approach for epilepsy.

Regulatory network analysis based on integrated miRNA-TF reveals key genes in heart failure

The etiology and pathophysiology of heart failure are still unknown. Increasing evidence suggests that abnormal microRNAs (miRNAs) and transcription factors (TFs) expression may be associated with the development of heart failure. Therefore, this study aims to explore key miRNAs, TFs, and related genes in heart failure to gain a greater understanding of the pathogenesis of heart failure. To search and download the dataset of mRNA chips related to heart failure from the GEO database (GSE59867, GSE9128, and GSE134766), we analyzed differential genes and screened the common differentially expressed genes on two chips using R language software. The binary interactions and circuits among miRNAs, TFs, and corresponding genes were determined by Pearson correlation coefficient. A regulatory network of miRNAs, TFs, and target genes was constructed based on bioinformatics. By comparing the sequences of patients with and without heart failure, five downregulated genes with hypermethylated mRNA and three upregulated genes with hypomethylated mRNA were identified. The miRNA-TF gene regulatory network consisted of 26 miRNAs, 22 TFs and six genes. GO and KEGG analysis results revealed that BP terms like cellular response to organic substance, cellular response to cytokine stimulus, and KEGG pathways like osteoclast differentiation, MAPK signaling pathway, and legionellosis were enriched of the DEGs. TMEM87A, PPP2R2A, DUSP1, and miR-92a have great potential as biomarkers for heart failure. The integrated analysis of the mRNA expression spectrum and microRNA-transcription factor-gene revealed the regulatory network of heart failure, which may provide clues to its alternative treatment.

Cannabinoids' Role in Modulating Central and Peripheral Immunity in Neurodegenerative Diseases

Cannabinoids (the endocannabinoids, the synthetic cannabinoids, and the phytocannabinoids) are well known for their various pharmacological properties, including neuroprotective and anti-inflammatory features, which are fundamentally important for the treatment of neurodegenerative diseases. The aging of the global population is causing an increase in these diseases that require the development of effective drugs to be even more urgent. Taking into account the unavailability of effective drugs for neurodegenerative diseases, it seems appropriate to consider the role of cannabinoids in the treatment of these diseases. To our knowledge, few reviews are devoted to cannabinoids' impact on modulating central and peripheral immunity in neurodegenerative diseases. The objective of this review is to provide the best possible information about the cannabinoid receptors and immuno-modulation features, peripheral immune modulation by cannabinoids, cannabinoid-based therapies for the treatment of neurological disorders, and the future development prospects of making cannabinoids versatile tools in the pursuit of effective drugs.

Exploring the 1,3-benzoxazine chemotype for cannabinoid receptor 2 as a promising anti-cancer therapeutic

The discovery of selective agonists of cannabinoid receptor 2 (CB2) is strongly pursued to successfully tuning endocannabinoid signaling for therapeutic purposes. However, the design of selective CB2 agonists is still challenging because of the high homology with the cannabinoid receptor 1 (CB1) and for the yet unclear molecular basis of the agonist/antagonist switch. Here, the 1,3-benzoxazine scaffold is presented as a versatile chemotype for the design of CB2 agonists from which 25 derivatives were synthesized. Among these, compound 7b5 (CB2 EC50 = 110 nM, CB1 EC50 > 10 μM) demonstrated to impair proliferation of triple negative breast cancer BT549 cells and to attenuate the release of pro-inflammatory cytokines in a CB2-dependent manner. Furthermore, 7b5 abrogated the activation of extracellular signal-regulated kinase (ERK) 1/2, a key pro-inflammatory and oncogenic enzyme. Finally, molecular dynamics studies suggested a new rationale for the in vitro measured selectivity and for the observed agonist behavior.

MicroRNA therapeutics and nucleic acid nano-delivery systems in bacterial infection: a review

Bacteria that have worked with humans for thousands of years pose a major threat to human health even today, as drug resistance has become a prominent problem. Compared to conventional drug therapy, nucleic acid-based therapies are a promising and potential therapeutic strategy for diseases in which nucleic acids are delivered through a nucleic acid delivery system to regulate gene expression in specific cells, offering the possibility of curing intractable diseases that are difficult to treat at this stage. Among the many nucleic acid therapeutic ideas, microRNA, a class of small nucleic acids with special properties, has made great strides in biology and medicine in just over two decades, showing promise in preclinical drug development. In this review, we introduce recent advances in nucleic acid delivery systems and their clinical applications, highlighting the potential of nucleic acid therapies, especially miRNAs extracted from traditional herbs, in combination with the existing set of nucleic acid therapeutic systems, to potentially open up a new line of thought in the treatment of cancer, viruses, and especially bacterial infectious diseases.

EVs-mediated delivery of CB2 receptor agonist for Alzheimer's disease therapy

Alzheimer's disease (AD) is a typical neurodegenerative disease that leads to irreversible neuronal degeneration, and effective treatment remains elusive due to the unclear mechanism. We utilized biocompatible mesenchymal stem cell-derived extracellular vesicles as carriers loaded with the CB2 target medicine AM1241 (EVs-AM1241) to protect against neurodegenerative progression and neuronal function in AD model mice. According to the results, EVs-AM1241 were successfully constructed and exhibited better bioavailability and therapeutic effects than bare AM1241. The Morris water maze (MWM) and fear conditioning tests revealed that the learning and memory of EVs-AM1241-treated model mice were significantly improved. In vivo electrophysiological recording of CA1 neurons indicated enhanced response to an auditory conditioned stimulus following fear learning. Immunostaining and Western blot analysis showed that amyloid plaque deposition and amyloid β (Aβ)-induced neuronal apoptosis were significantly suppressed by EVs-AM1241. Moreover, EVs-AM1241 increased the number of neurons and restored the neuronal cytoskeleton, indicating that they enhanced neuronal regeneration. RNA sequencing revealed that EVs-AM1241 facilitated Aβ phagocytosis, promoted neurogenesis and ultimately improved learning and memory through the calcium-Erk signaling pathway. Our study showed that EVs-AM1241 efficiently reversed neurodegenerative pathology and enhanced neurogenesis in model mice, indicating that they are very promising particles for treating AD.

Current advancements and future perspectives of long noncoding RNAs in lipid metabolism and signaling

BACKGROUND

The investigation of lncRNAs has provided a novel perspective for elucidating mechanisms underlying diverse physiological and pathological processes. Compelling evidence has revealed an intrinsic link between lncRNAs and lipid metabolism, demonstrating that lncRNAs-induced disruption of lipid metabolism and signaling contribute to the development of multiple cancers and some other diseases, including obesity, fatty liver disease, and cardiovascular disease.

AIMOF REVIEW

The current review summarizes the recent advances in basic research about lipid metabolism and lipid signaling-related lncRNAs. Meanwhile, the potential and challenges of targeting lncRNA for the therapy of cancers and other lipid metabolism-related diseases are also discussed.

KEY SCIENTIFIC CONCEPT OF REVIEW

Compared with the substantial number of lncRNA loci, we still know little about the role of lncRNAs in metabolism. A more comprehensive understanding of the function and mechanism of lncRNAs may provide a new standpoint for the study of lipid metabolism and signaling. Developing lncRNA-based therapeutic approaches is an effective strategy for lipid metabolism-related diseases.

CB2 receptor in the CNS: from immune and neuronal modulation to behavior

Despite low levels of cannabinoid receptor type 2 (CB2R) expression in the central nervous system in human and rodents, a growing body of evidence shows CB2R involvement in many processes at the behavioral level, through both immune and neuronal modulations. Recent in vitro and in vivo evidence have highlighted the complex role of CB2R under physiological and inflammatory conditions. Under neuroinflammatory states, its activation seems to protect the brain and its functions, making it a promising target in a wide range of neurological disorders. Here, we provide a complete and updated overview of CB2R function in the central nervous system of rodents, spanning from modulation of immune function in microglia but also in other cell types, to behavior and neuronal activity, in both physiological and neuroinflammatory contexts.

Dysregulation of Serum MicroRNA after Intracerebral Hemorrhage in Aged Mice

Stroke is one of the most common diseases that leads to brain injury and mortality in patients, and intracerebral hemorrhage (ICH) is the most devastating subtype of stroke. Though the prevalence of ICH increases with aging, the effect of aging on the pathophysiology of ICH remains largely understudied. Moreover, there is no effective treatment for ICH. Recent studies have demonstrated the potential of circulating microRNAs as non-invasive diagnostic and prognostic biomarkers in various pathological conditions. While many studies have identified microRNAs that play roles in the pathophysiology of brain injury, few demonstrated their functions and roles after ICH. Given this significant knowledge gap, the present study aims to identify microRNAs that could serve as potential biomarkers of ICH in the elderly. To this end, sham or ICH was induced in aged C57BL/6 mice (18–24 months), and 24 h post-ICH, serum microRNAs were isolated, and expressions were analyzed. We identified 28 significantly dysregulated microRNAs between ICH and sham groups, suggesting their potential to serve as blood biomarkers of acute ICH. Among those microRNAs, based on the current literature, miR-124-3p, miR-137-5p, miR-138-5p, miR-219a-2-3p, miR-135a-5p, miR-541-5p, and miR-770-3p may serve as the most promising blood biomarker candidates of ICH, warranting further investigation.

Endocannabinoid signaling in the central nervous system

It is hard to overestimate the influence of the endocannabinoid signaling (ECS) system on central nervous system (CNS) function. In the 40 years since cannabinoids were found to trigger specific cell signaling cascades, studies of the ECS system continue to cause amazement, surprise, and confusion! CB1 cannabinoid receptors are expressed widely in the CNS and regulate cell-cell communication via effects on the release of both neurotransmitters and gliotransmitters. CB2 cannabinoid receptors are difficult to detect in the CNS but seem to "punch above their weight" as compounds targeting these receptors have significant effects on inflammatory state and behavior. Positive and negative allosteric modulators for both receptors have been identified and examined in preclinical studies. Concentrations of the endocannabinoid ligands, N-arachidonoylethanolamine and 2-arachidonoylglycerol (2-AG), are regulated by a combination of enzymatic synthesis and degradation and inhibitors of these processes are available and making their way into clinical trials. Importantly, ECS regulates many essential brain functions, including regulation of reward, anxiety, inflammation, motor control, and cellular development. While the field is on the cusp of preclinical discoveries providing impactful clinical and therapeutic insights into many CNS disorders, there is still much to be learned about this remarkable and versatile modulatory system.

The Role of Cannabinoid Type 2 Receptors in Parkinson's Disease

Parkinson's disease (PD) is the second most frequent neurodegenerative disease and currently represents a clear unmet medical need. Therefore, novel preventive and therapeutic strategies are needed. Cannabinoid type 2 (CB2) receptors, one of the components of the endocannabinoid system, can regulate neuroinflammation in PD. Here, we review the current preclinical and clinical studies investigating the CB2 receptors in PD with the aim to clarify if these receptors could have a role in PD. Preclinical data show that CB2 receptors could have a neuroprotective action in PD and that the therapeutic targeting of CB2 receptors could be promising. Indeed, it has been shown that different CB2 receptor-selective agonists exert protective effects in different PD models. Moreover, the alterations in the expression of CB2 receptors observed in brain tissues from PD animal models and PD patients suggest the potential value of CB2 receptors as possible novel biomarkers for PD. However, to date, there is no direct evidence of the role of CB2 receptors in PD. Further studies are strongly needed in order to fully clarify the role of CB2 receptors in PD and thus pave the way to novel possible diagnostic and therapeutic opportunities for PD.

Molecular Insights into Epigenetics and Cannabinoid Receptors

The actions of cannabis are mediated by G protein-coupled receptors that are part of an endogenous cannabinoid system (ECS). ECS consists of the naturally occurring ligands N-arachidonylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), their biosynthetic and degradative enzymes, and the CB1 and CB2 cannabinoid receptors. Epigenetics are heritable changes that affect gene expression without changing the DNA sequence, transducing external stimuli in stable alterations of the DNA or chromatin structure. Cannabinoid receptors are crucial candidates for exploring their functions through epigenetic approaches due to their significant roles in health and diseases. Epigenetic changes usually promote alterations in the expression of genes and proteins that can be evaluated by various transcriptomic and proteomic analyses. Despite the exponential growth of new evidence on the critical functions of cannabinoid receptors, much is still unknown regarding the contribution of various genetic and epigenetic factors that regulate cannabinoid receptor gene expression. Recent studies have identified several immediate and long-lasting epigenetic changes, such as DNA methylation, DNA-associated histone proteins, and RNA regulatory networks, in cannabinoid receptor function. Thus, they can offer solutions to many cellular, molecular, and behavioral impairments found after modulation of cannabinoid receptor activities. In this review, we discuss the significant research advances in different epigenetic factors contributing to the regulation of cannabinoid receptors and their functions under both physiological and pathological conditions. Increasing our understanding of the epigenetics of cannabinoid receptors will significantly advance our knowledge and could lead to the identification of novel therapeutic targets and innovative treatment strategies for diseases associated with altered cannabinoid receptor functions.

Effects of Ethanol on Expression of Coding and Noncoding RNAs in Murine Neuroblastoma Neuro2a Cells

Excessive use of alcohol can induce neurobiological and neuropathological alterations in the brain, including the hippocampus and forebrain, through changes in neurotransmitter systems, hormonal systems, and neuroimmune processes. We aimed to investigate the effects of ethanol on the expression of coding and noncoding RNAs in a brain-derived cell line exposed to ethanol. After exposing Neuro2a cells, a neuroblastoma cell line, to ethanol for 24 and 72 h, we observed cell proliferation and analyzed up- and downregulated mRNAs and long noncoding RNAs (lncRNAs) using total RNA-Seq technology. We validated the differential expression of some mRNAs and lncRNAs by RT-qPCR and analyzed the expression of Cebpd and Rnu3a through knock-down of Cebpd. Cell proliferation was significantly reduced in cells exposed to 100 mM ethanol for 72 h, with 1773 transcripts up- or downregulated by greater than three-fold in ethanol-treated cells compared to controls. Of these, 514 were identified as lncRNAs. Differentially expressed mRNAs and lncRNAs were mainly observed in cells exposed to ethanol for 72 h, in which Atm and Cnr1 decreased, but Trib3, Cebpd, and Spdef increased. On the other hand, lncRNAs Kcnq1ot1, Tug1, and Xist were changed by ethanol, and Rnu3a in particular was greatly increased by chronic ethanol treatment through inhibition of Cebpd. Our results increase the understanding of cellular and molecular mechanisms related to coding and noncoding RNAs in an in vitro model of acute and chronic exposure to ethanol.

Dysregulated miRNAs as Biomarkers and Therapeutical Targets in Neurodegenerative Diseases

Alzheimer’s disease (AD), Parkinson’s disease (PD), and Amyotrophic Lateral Sclerosis (ALS) are representative neurodegenerative diseases (NDs) characterized by degeneration of selective neurons, as well as the lack of effective biomarkers and therapeutic treatments. In the last decade, microRNAs (miRNAs) have gained considerable interest in diagnostics and therapy of NDs, owing to their aberrant expression and their ability to target multiple molecules and pathways. Here, we provide an overview of dysregulated miRNAs in fluids (blood or cerebrospinal fluid) and nervous tissue of AD, PD, and ALS patients. By emphasizing those that are commonly dysregulated in these NDs, we highlight their potential role as biomarkers or therapeutical targets and describe the use of antisense oligonucleotides as miRNA therapies.

Parkinson's disease related alterations in cannabinoid transmission

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic (DAergic) neurons of the substantia nigra pars compacta (SNc) by neurodegeneration. Recent findings in animal models of PD propose tonic inhibition of the remaining DA neurons through GABA release from reactive glial cells. Movement dysfunctions could be ameliorated by promotion of activity in dormant DA cells. The endocannabinoid system (ECS) is extensively present in basal ganglia (BG) and is known as an indirect modulator of DAergic neurotransmission, thus drugs designed to target this system have shown promising therapeutic potential in PD patients. Interestingly, down/up-regulation of cannabinoid receptors (CBRs) varies across the different stages of PD, suggesting that some of the motor/ non-motor deficits may be related to changes in CBRs. Determination of the profile of changes of these receptors across the different stages of PD as well as their neural distribution within the BG could improve understanding of PD and identify pathways important in disease pathobiology. In this review, we focus on temporal and spatial alterations of CBRs during PD in the BG. At present, as inconclusive, but suggestive results have been obtained, future investigations should be conducted to extend preclinical studies examining CBRs changes within each stage in controlled clinical trials in order to determine the potential of targeting CBRs in management of PD.

Identification of the Ghrelin and Cannabinoid CB2 Receptor Heteromer Functionality and Marked Upregulation in Striatal Neurons from Offspring of Mice under a High-Fat Diet

Cannabinoids have been reported as orexigenic, i.e., as promoting food intake that, among others, is controlled by the so-called “hunger” hormone, ghrelin. The aim of this paper was to look for functional and/or molecular interactions between ghrelin GHSR1a and cannabinoid CB₂ receptors at the central nervous system (CNS) level. In a heterologous system we identified CB₂-GHSR1a receptor complexes with a particular heteromer print consisting of impairment of CB₂ receptor/G_i-mediated signaling. The blockade was due to allosteric interactions within the heteromeric complex as it was reverted by antagonists of the GHSR1a receptor. Cannabinoids acting on the CB₂ receptor did not affect cytosolic increases of calcium ions induced by ghrelin acting on the GHSR1a receptor. In situ proximity ligation imaging assays confirmed the expression of CB₂-GHSR1a receptor complexes in both heterologous cells and primary striatal neurons. We tested heteromer expression in neurons from offspring of high-fat-diet mouse mothers as they have more risk to be obese. Interestingly, there was a marked upregulation of those complexes in striatal neurons from siblings of pregnant female mice under a high-fat diet.

Biological Function of Long Non-coding RNA (LncRNA) Xist

Long non-coding RNAs (lncRNAs) regulate gene expression in a variety of ways at epigenetic, chromatin remodeling, transcriptional, and translational levels. Accumulating evidence suggests that lncRNA X-inactive specific transcript (lncRNA Xist) serves as an important regulator of cell growth and development. Despites its original roles in X-chromosome dosage compensation, lncRNA Xist also participates in the development of tumor and other human diseases by functioning as a competing endogenous RNA (ceRNA). In this review, we comprehensively summarized recent progress in understanding the cellular functions of lncRNA Xist in mammalian cells and discussed current knowledge regarding the ceRNA network of lncRNA Xist in various diseases. Long non-coding RNAs (lncRNAs) are transcripts that are more than 200 nt in length and without an apparent protein-coding capacity (Furlan and Rougeulle, 2016; Maduro et al., 2016). These RNAs are believed to be transcribed by the approximately 98-99% non-coding regions of the human genome (Derrien et al., 2012; Fu, 2014; Montalbano et al., 2017; Slack and Chinnaiyan, 2019), as well as a large variety of genomic regions, such as exonic, tronic, and intergenic regions. Hence, lncRNAs are also divided into eight categories: Intergenic lncRNAs, Intronic lncRNAs, Enhancer lncRNAs, Promoter lncRNAs, Natural antisense/sense lncRNAs, Small nucleolar RNA-ended lncRNAs (sno-lncRNAs), Bidirectional lncRNAs, and non-poly(A) lncRNAs (Ma et al., 2013; Devaux et al., 2015; St Laurent et al., 2015; Chen, 2016; Quinn and Chang, 2016; Richard and Eichhorn, 2018; Connerty et al., 2020). A range of evidence has suggested that lncRNAs function as key regulators in crucial cellular functions, including proliferation, differentiation, apoptosis, migration, and invasion, by regulating the expression level of target genes via epigenomic, transcriptional, or post-transcriptional approaches (Cao et al., 2018). Moreover, lncRNAs detected in body fluids were also believed to serve as potential biomarkers for the diagnosis, prognosis, and monitoring of disease progression, and act as novel and potential drug targets for therapeutic exploitation in human disease (Jiang W. et al., 2018; Zhou et al., 2019a). Long non-coding RNA X-inactive specific transcript (lncRNA Xist) are a set of 15,000-20,000 nt sequences localized in the X chromosome inactivation center (XIC) of chromosome Xq13.2 (Brown et al., 1992; Debrand et al., 1998; Kay, 1998; Lee et al., 2013; da Rocha and Heard, 2017; Yang Z. et al., 2018; Brockdorff, 2019). Previous studies have indicated that lncRNA Xist regulate X chromosome inactivation (XCI), resulting in the inheritable silencing of one of the X-chromosomes during female cell development. Also, it serves a vital regulatory function in the whole spectrum of human disease (notably cancer) and can be used as a novel diagnostic and prognostic biomarker and as a potential therapeutic target for human disease in the clinic (Liu et al., 2018b; Deng et al., 2019; Dinescu et al., 2019; Mutzel and Schulz, 2020; Patrat et al., 2020; Wang et al., 2020a). In particular, lncRNA Xist have been demonstrated to be involved in the development of multiple types of tumors including brain tumor, Leukemia, lung cancer, breast cancer, and liver cancer, with the prominent examples outlined in Table 1. It was also believed that lncRNA Xist (Chaligne and Heard, 2014; Yang Z. et al., 2018) contributed to other diseases, such as pulmonary fibrosis, inflammation, neuropathic pain, cardiomyocyte hypertrophy, and osteoarthritis chondrocytes, and more specific details can be found in Table 2. This review summarizes the current knowledge on the regulatory mechanisms of lncRNA Xist on both chromosome dosage compensation and pathogenesis (especially cancer) processes, with a focus on the regulatory network of lncRNA Xist in human disease.

Cannabinoid receptor CB2 ablation protects against TAU induced neurodegeneration

Tauopathies are a group of neurodegenerative diseases characterized by the alteration/aggregation of TAU protein, for which there is still no effective treatment. Therefore, new pharmacological targets are being sought, such as elements of the endocannabinoid system (ECS). We analysed the occurrence of changes in the ECS in tauopathies and their implication in the pathogenesis. By integrating gene expression analysis, immunofluorescence, genetic and adeno-associated virus expressing TAU mouse models, we found a TAU-dependent increase in CB₂ receptor expression in hippocampal neurons, that occurs as an early event in the pathology and was maintained until late stages. These changes were accompanied by alterations in the endocannabinoid metabolism. Remarkably, CB₂ ablation in mice protects from neurodegeneration induced by hTAU^P301L overexpression, corroborated at the level of cognitive behaviour, synaptic plasticity, and aggregates of insoluble TAU. At the level of neuroinflammation, the absence of CB₂ did not produce significant changes in concordance with a possible neuronal location rather than its classic glial expression in these models. These findings were corroborated in post-mortem samples of patients with Alzheimer's disease, the most common tauopathy. Our results show that neurons with accumulated TAU induce the expression of the CB₂ receptor, which enhances neurodegeneration. These results are important for our understanding of disease mechanisms, providing a novel therapeutic strategy to be investigated in tauopathies.

Beneficial effects of the phytocannabinoid Δ9-THCV in L-DOPA-induced dyskinesia in Parkinson's disease

The antioxidant and CB₂ receptor agonist properties of Δ⁹-tetrahydrocannabivarin (Δ⁹-THCV) afforded neuroprotection in experimental Parkinson's disease (PD), whereas its CB₁ receptor antagonist profile at doses lower than 5 mg/kg caused anti-hypokinetic effects. In the present study, we investigated the anti-dyskinetic potential of Δ⁹-THCV (administered i.p. at 2 mg/kg for two weeks), which had not been investigated before. This objective was investigated after inducing dyskinesia by repeated administration of L-DOPA (i.p. at 10 mg/kg) in a genetic model of dopaminergic deficiency, Pitx3^ak mutant mice, which serves as a useful model for testing anti-dyskinetic agents. The daily treatment of these mice with L-DOPA for two weeks progressively increased the time spent in abnormal involuntary movements (AIMs) and elevated their horizontal and vertical activities (as measured in a computer-aided actimeter), signs that reflected the dyskinetic state of these mice. Interestingly, when combined with L-DOPA from the first injection, Δ⁹-THCV delayed the appearance of all these signs and decreased their intensity, with a reduction in the levels of FosB protein and the histone pAcH3 (measured by immunohistochemistry), which had previously been found to be elevated in the basal ganglia in L-DOPA-induced dyskinesia. In addition to the anti-dyskinetic effects of Δ⁹-THCV when administered at the onset of L-DOPA treatment, Δ⁹-THCV was also effective in attenuating the intensity of dyskinesia when administered for three consecutive days once these signs were already present (two weeks after the onset of L-DOPA treatment). In summary, our data support the anti-dyskinetic potential of Δ⁹-THCV, both to delay the occurrence and to attenuate the magnitude of dyskinetic signs. Although further studies are clearly required to determine the clinical significance of these data in humans, the results nevertheless situate Δ⁹-THCV in a promising position for developing a cannabinoid-based therapy for patients with PD.