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BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) has rapidly become the most common cause of chronic liver disease in children and adolescents, but its etiology remains largely unknown. Adrenarche is a critical phase for hormonal changes, and any disturbance during this period has been linked to metabolic disorders, including obesity and dyslipidemia. However, whether there is a causal linkage between adrenarche disturbance and the increasing prevalence of NAFLD in children remains unclear. RESULTS: Using the young female rat as a model, we found that the liver undergoes a transient slowdown period of growth along with the rise of adrenal-derived sex steroid precursors during adrenarche. Specifically blocking androgen actions across adrenarche phase using androgen receptor antagonist flutamide largely increased liver weight by 47.97% and caused marked fat deposition in liver, thus leading to severe NAFLD in young female rats. Conversely, further administrating nonaromatic dihydrotestosterone (DHT) into young female rats across adrenarche phase could effectively reduce liver fat deposition. But, administration of the aromatase inhibitor, formestane across adrenarche had minimal effects on hepatic de novo fatty acid synthesis and liver fat deposition, suggesting adrenal-derived sex steroid precursors exert their anti-NAFLD effects in young females by converting into active androgens rather than into active estrogens. Mechanistically, transcriptomic profiling and integrated data analysis revealed that active androgens converted from the adrenal sex steroid precursors prevent NAFLD in young females primarily by inactivating hepatic sterol regulatory element-binding transcription factor 1 (Srebf1) signaling. CONCLUSIONS: We firstly evidenced that adrenarche-accompanied rise of sex steroid precursors plays a predominant role in preventing the incidence of NAFLD in young females by converting into active androgens and inactivating hepatic Srebf1 signaling. Our novel finding provides new insights into the etiology of NAFLD and is crucial in developing effective prevention and management strategies for NAFLD in children.
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Adrenarca , Hepatopatia Gordurosa não Alcoólica , Proteína de Ligação a Elemento Regulador de Esterol 1 , Animais , Criança , Feminino , Humanos , Ratos , Androgênios , Fígado/metabolismo , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/prevenção & controle , Hepatopatia Gordurosa não Alcoólica/metabolismo , Esteroides , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismoRESUMO
Positive feedback driven by transcriptional regulation has long been considered a key mechanism underlying cell lineage segregation during embryogenesis. Using the developing spinal cord as a paradigm, we found that canonical, transcription-driven feedback cannot explain robust lineage segregation of motor neuron subtypes marked by two cardinal factors, Hoxa5 and Hoxc8. We propose a feedback mechanism involving elementary microRNA-mRNA reaction circuits that differ from known feedback loop-like structures. Strikingly, we show that a wide range of biologically plausible post-transcriptional regulatory parameters are sufficient to generate bistable switches, a hallmark of positive feedback. Through mathematical analysis, we explain intuitively the hidden source of this feedback. Using embryonic stem cell differentiation and mouse genetics, we corroborate that microRNA-mRNA circuits govern tissue boundaries and hysteresis upon motor neuron differentiation with respect to transient morphogen signals. Our findings reveal a previously underappreciated feedback mechanism that may have widespread functions in cell fate decisions and tissue patterning.
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Diferenciação Celular/genética , Linhagem da Célula/genética , Retroalimentação Fisiológica , MicroRNAs/genética , Neurônios Motores/metabolismo , Medula Espinal/citologia , Animais , Sequência de Bases , Feminino , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Proteínas de Homeodomínio/metabolismo , Cinética , Masculino , Camundongos Endogâmicos C57BL , MicroRNAs/metabolismo , Modelos Biológicos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA-Seq , Transdução de Sinais , Análise de Célula Única , Fatores de Transcrição/metabolismo , Transcrição Gênica , Tretinoína/metabolismoRESUMO
N6-methyladenosine (m6A) is the most prevalent, conserved, and abundant RNA modification of the mRNAs of most eukaryotes, including mammals. Similar to epigenetic DNA modifications, m6A has been proposed to function as a critical regulator for gene expression. This modification is installed by m6A methylation "writers" (Mettl3/Mettl14 methyltransferase complex), and it can be reversed by demethylase "erasers" (Fto and Alkbh5). Furthermore, m6A can be recognized by "readers" (Ythdf and Ythdc families), which may be interpreted to affect mRNA splicing, stability, translation or localization. Levels of m6A methylation appear to be highest in the brain, where it plays important functions during embryonic stem cell differentiation, brain development, and neurodevelopmental disorders. Depletion of the m6A methylation writer Mettl14 from mouse embryonic nervous systems prolongs cell cycle progression of radial glia and extends cortical neurogenesis into postnatal stages. Recent studies further imply that dysregulated m6A methylation may be significantly correlated with neurodegenerative diseases. In this review, we give an overview of m6A modifications during neural development and associated disorders, and provide perspectives for studying m6A methylation.
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Adenosina/análogos & derivados , Epigênese Genética , Degeneração Neural/genética , Neurogênese/genética , Transcriptoma , Adenosina/genética , Animais , Humanos , CamundongosRESUMO
Long non-coding RNAs (lncRNAs) have gained increasing attention as they exhibit highly tissue- and cell-type specific expression patterns. LncRNAs are highly expressed in the central nervous system and their roles in the brain have been studied intensively in recent years, but their roles in the spinal motor neurons (MNs) are largely unexplored. Spinal MN development is controlled by precise expression of a gene regulatory network mediated spatiotemporally by transcription factors, representing an elegant paradigm for deciphering the roles of lncRNAs during development. Moreover, many MN-related neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), are associated with RNA metabolism, yet the link between MN-related diseases and lncRNAs remains obscure. In this review, we summarize lncRNAs known to be involved in MN development and disease, and discuss their potential future therapeutic applications.
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Esclerose Lateral Amiotrófica/genética , Neurônios Motores/fisiologia , Atrofia Muscular Espinal/genética , RNA Longo não Codificante/genética , Animais , Humanos , Camundongos , Doenças Neurodegenerativas/genéticaRESUMO
G protein-coupled receptor 25 (GPR25) is an orphan G protein-coupled receptor in vertebrates, that has been implicated to be associated with autoimmune diseases and regulate blood pressure in humans. However, the endogenous ligand of GPR25 remains unknown in vertebrates. Here, we reported that in non-mammalian vertebrates (zebrafish, spotted gars, and pigeons), GPR25 could be activated by Apelin and Apela peptides, which are also the two endogenous ligands of vertebrate Apelin receptor (APLNR). Using the pGL3-CRE-luciferase reporter assay and confocal microscopy, we first demonstrated that like APLNR, zebrafish GPR25 expressing in HEK293â¯cells could be effectively activated by zebrafish Apelin and Apela peptides, leading to the inhibition of forskolin-stimulated cAMP production and receptor internalization. Like zebrafish GPR25, pigeon and spotted gar GPR25 could also be activated by Apelin and Apela, and their activation could inhibit forskolin-induced cAMP accumulation. Interestingly, unlike zebrafish (/spotted gar/pigeon) GPR25, human GPR25 could not be activated by Apelin and Apela under the same experimental conditions. RNA-seq analysis further revealed that GPR25 is expressed in a variety of tissues, including the testes and intestine of zebrafish/spotted gars/humans, implying the potential roles of GPR25 signaling in many physiological processes in vertebrates. Taken together, our data not only provides the first proof that the orphan receptor GPR25 possesses two potential ligands 'Apelin and Apela' and its activation decreases intracellular cAMP levels in non-mammalian vertebrates, but also facilitates to unravel the physiological roles of GPR25 signaling in vertebrates.
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Quimiocinas/metabolismo , Receptores Acoplados a Proteínas G/genética , Proteínas de Peixe-Zebra/metabolismo , Animais , Quimiocinas/genética , Clonagem Molecular , Columbidae/genética , AMP Cíclico/metabolismo , Proteínas de Peixes/genética , Células HEK293 , Humanos , Receptores Acoplados a Proteínas G/metabolismo , Vertebrados/genética , Proteínas de Peixe-Zebra/genéticaRESUMO
MicroRNAs regulate gene expression in diverse physiological scenarios. Their role in the control of morphogen related signaling pathways has been less studied, particularly in the context of embryonic Central Nervous System (CNS) development. Here, we uncover a role for microRNAs in limiting the spatiotemporal range of morphogen expression and function. Wnt1 is a key morphogen in the embryonic midbrain, and directs proliferation, survival, patterning and neurogenesis. We reveal an autoregulatory negative feedback loop between the transcription factor Lmx1b and a newly characterized microRNA, miR135a2, which modulates the extent of Wnt1/Wnt signaling and the size of the dopamine progenitor domain. Conditional gain of function studies reveal that Lmx1b promotes Wnt1/Wnt signaling, and thereby increases midbrain size and dopamine progenitor allocation. Conditional removal of Lmx1b has the opposite effect, in that expansion of the dopamine progenitor domain is severely compromised. Next, we provide evidence that microRNAs are involved in restricting dopamine progenitor allocation. Conditional loss of Dicer1 in embryonic stem cells (ESCs) results in expanded Lmx1a/b+ progenitors. In contrast, forced elevation of miR135a2 during an early window in vivo phenocopies the Lmx1b conditional knockout. When En1::Cre, but not Shh::Cre or Nes::Cre, is used for recombination, the expansion of Lmx1a/b+ progenitors is selectively reduced. Bioinformatics and luciferase assay data suggests that miR135a2 targets Lmx1b and many genes in the Wnt signaling pathway, including Ccnd1, Gsk3b, and Tcf7l2. Consistent with this, we demonstrate that this mutant displays reductions in the size of the Lmx1b/Wnt1 domain and range of canonical Wnt signaling. We posit that microRNA modulation of the Lmx1b/Wnt axis in the early midbrain/isthmus could determine midbrain size and allocation of dopamine progenitors. Since canonical Wnt activity has recently been recognized as a key ingredient for programming ESCs towards a dopaminergic fate in vitro, these studies could impact the rational design of such protocols.
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Proteínas com Homeodomínio LIM/genética , MicroRNAs/metabolismo , Neurogênese/genética , Doença de Parkinson/genética , Fatores de Transcrição/genética , Proteína Wnt1/genética , Animais , Diferenciação Celular/genética , RNA Helicases DEAD-box/metabolismo , Dopamina/metabolismo , Neurônios Dopaminérgicos/citologia , Neurônios Dopaminérgicos/metabolismo , Embrião de Mamíferos , Células-Tronco Embrionárias , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Proteínas com Homeodomínio LIM/metabolismo , Mesencéfalo/crescimento & desenvolvimento , Mesencéfalo/metabolismo , Camundongos , MicroRNAs/genética , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Ribonuclease III/metabolismo , Fatores de Transcrição/metabolismo , Via de Sinalização Wnt/genéticaRESUMO
MicroRNAs (miRNAs) are pivotal regulators of gene expression and are involved in biological processes spanning from early developmental stages to the intricate process of aging. Extensive research has underscored the fundamental role of miRNAs in orchestrating eukaryotic development, with disruptions in miRNA biogenesis resulting in early lethality. Moreover, perturbations in miRNA function have been implicated in the aging process, particularly in model organisms such as nematodes and flies. miRNAs tend to be clustered in vertebrate genomes, finely modulating an array of biological pathways through clustering within a single transcript. Although extensive research of their developmental roles has been conducted, the potential implications of miRNA clusters in regulating aging remain largely unclear. In this review, we use the Mir-23-27-24 cluster as a paradigm, shedding light on the nuanced physiological functions of miRNA clusters during embryonic development and exploring their potential involvement in the aging process. Moreover, we advocate further research into the intricate interplay among miRNA clusters, particularly the Mir-23-27-24 cluster, in shaping the regulatory landscape of aging.
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Envelhecimento , Regulação da Expressão Gênica no Desenvolvimento , MicroRNAs , Família Multigênica , MicroRNAs/genética , Animais , Envelhecimento/genética , Humanos , Desenvolvimento Embrionário/genéticaRESUMO
INTRODUCTION: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have attracted much attention because of their significant hypoglycemic and weight-loss effects. Previous preparations can only be subcutaneously injected. Oral administration of GLP-1RAs semaglutide helps to broaden treatment options, but its safety in the real world still needs to be observed. This study is based on FDA adverse event reporting system (FAERS) database to mine adverse drug events (ADE) of oral semaglutide, and provide references for the clinical safe use of this drug. METHODS: To analyze the signal quality of oral semaglutide, which is a drug used in the FAERS database from the third quarter of 2019 to the third quarter of 2023, we collected ADE data and performed data mining by using disproportionate analysis. Then, we standardized the data and used a variety of signal-quantification techniques, including reported odds ratio (ROR), proportional reporting ratio (PRR), Bayesian belief propagation neural network (BCPNN), and multiple empirical Bayesian gamma Poisson contractions (MGPS), for further analysis. RESULTS: We screened 2398 reports on the use of semaglutide tablets, involving a total of 5653 ADE. These reports were mainly submitted by consumers, and the reporting country was mainly the United States. A total of 23 system organ classes (SOC) and 93 preferred terms (PT) were mined for the signals of semaglutide tablets. The three most common SOC were gastrointestinal disorders, general disorders and administration site conditions, and investigations. At the PT level, metabolism and nutrition disorders exhibit the highest number of signals, with the top three being thyroid cyst, acute cholecystitis, and ketosis. Gastrointestinal disorders rank second, primarily involving eructation, pancreatitis, impaired gastric emptying, and regurgitation. In addition, vith nerve paralysis occurs and the signal intensity is high. CONCLUSIONS: Our study provides a deeper and broader understanding of the safety of oral semaglutide. The results of the ROR, PRR, BCPNN, and MGPS algorithms exhibit high consistency, with metabolism and nutrition-related disorders having the highest number of signals. The conclusions align with the technical specifications of the product. Notably, other unexpected effects are reported, including acute cholecystitis, paralysis of the abducens nerve, and positional vertigo.
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Background: Metabolic syndrome (MetS) is a global health concern, and it is particularly harmful to middle-aged and elderly individuals. Life Element Eight (LE8), a measure to improve cardiovascular health, may offer benefits for MetS. Herein, we examined the relationship between LE8 and MetS among middle-aged and elderly individuals, and elucidated the role of biological aging and inflammation in this process. Methods: We obtained the LE8 scores of 2,901 Americans, along with their biological aging indicators (Biological age, Phenotypic age, Serum Klotho), and computed their inflammatory indicators SII, DII. Using logistic regression model, we assessed the association among inflammatory markers, Biological aging, LE8 and MetS. Additionally, we generated restricted cubic spline (RCS) plots to display trends in significant variables in logistic regression. Using parallel mediation analysis, we evaluated the possible mediating role of various factors in the risk relationship between LE8 and MetS. Results: Our examination revealed that higher LE8 scores were associated with a lower incidence of MetS in a fully adjusted model. The high LE8 subgroup had a 79.73% reduction in the risk of MetS compared to the low subgroup with an OR = 0.2027 (95% Cl 0.0871, 0.4714), with similar correlations between health factor scores and MetS risk. Biological aging mediated the associations between LE8, health behaviors and health factor scores and MetS risk. Conclusion: A rise in the LE8 score among middle-aged and elderly individuals is a protective factor for MetS, and this association may be partially mediated by biological aging, suggesting that LE8 may reduce the risk of MetS by ameliorating aging.
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Long noncoding RNAs (lncRNAs) play pivotal roles in modulating gene expression during development and disease. Despite their high expression in the central nervous system (CNS), understanding the precise physiological functions of CNS-associated lncRNAs has been challenging, largely due to the in vitro-centric nature of studies in this field. Here, utilizing mouse embryonic stem cell (ESC)-derived motor neurons (MNs), we identified an unexplored MN-specific lncRNA, Litchi (Long Intergenic RNAs in Chat Intron). By employing an "exon-only" deletion strategy in ESCs and a mouse model, we reveal that Litchi deletion profoundly impacts MN dendritic complexity, axonal growth, and altered action potential patterns. Mechanistically, voltage-gated channels and neurite growth-related genes exhibited heightened sensitivity to Litchi deletion. Our Litchi-knockout mouse model displayed compromised motor behaviors and reduced muscle strength, highlighting Litchi's critical role in motor function. This study unveils an underappreciated function of lncRNAs in orchestrating MN maturation and maintaining robust electrophysiological properties.
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Spinal motor neurons (MNs) integrate sensory stimuli and brain commands to generate movements. In vertebrates, the molecular identities of the cardinal MN types such as those innervating limb versus trunk muscles are well elucidated. Yet the identities of finer subtypes within these cell populations that innervate individual muscle groups remain enigmatic. Here we investigate heterogeneity in mouse MNs using single-cell transcriptomics. Among limb-innervating MNs, we reveal a diverse neuropeptide code for delineating putative motor pool identities. Additionally, we uncover that axial MNs are subdivided into three molecularly distinct subtypes, defined by mediolaterally-biased Satb2, Nr2f2 or Bcl11b expression patterns with different axon guidance signatures. These three subtypes are present in chicken and human embryos, suggesting a conserved axial MN expression pattern across higher vertebrates. Overall, our study provides a molecular resource of spinal MN types and paves the way towards deciphering how neuronal subtypes evolved to accommodate vertebrate motor behaviors.
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Neurônios Motores , Transcriptoma , Animais , Camundongos , Humanos , Transcriptoma/genética , Neurônios Motores/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Músculo Esquelético/metabolismo , Embrião de Mamíferos/metabolismo , Medula Espinal/metabolismo , Mamíferos/metabolismo , Proteínas Repressoras/metabolismo , Proteínas Supressoras de Tumor/metabolismoRESUMO
Spinal muscular atrophy (SMA) is a neurodegenerative disease characterized by the selective loss of spinal motor neurons (MNs) and concomitant muscle weakness. Mutation of SMN1 is known to cause SMA, and restoring SMN protein levels via antisense oligonucleotide treatment is effective for ameliorating symptoms. However, this approach is hindered by exorbitant costs, invasive procedures, and poor treatment responses of some patients. Here, we seek to circumvent these hurdles by identifying reliable biomarkers that could predict treatment efficacy. We uncovered that MiR34 exhibits consistent downregulation during SMA progression in both human and rodent contexts. Importantly, Mir34 family-knockout mice display axon swelling and reduced neuromuscular junction (NMJ) endplates, recapitulating SMA pathology. Introducing MiR34a via scAAV9 improved the motor ability of SMNΔ7 mice, possibly by restoring NMJ endplate size. Finally, we observed a consistent decreasing trend in MiR34 family expression in the cerebrospinal fluid (CSF) of type I SMA patients during the loading phase of nusinersen treatment. Baseline CSF MiR34 levels before nusinersen injection proved predictive of patient motor skills 1 year later. Thus, we propose that MiR34 may serve as a biomarker of SMA since it is associated with the pathology and can help evaluate the therapeutic effects of nusinersen.
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Cardioneuroablation (CNA) is proposed as a promising therapy for patients with sinoatrial node dysfunction (SND) that is mediated by excessive vagal tone. However, a series of urgent questions about CNA remain unanswered. From December 2020 to March 2022, six patients with symptomatic SND who underwent CNA were summarized in this report. Sequential CNA targeting Ao-SVC GP, PMLGP, RAGP, and LSGP was performed in patients, guided by fractionated intracardiac electrograms and dynamically evaluated by extracardiac vagal stimulation (ECVS). The results showed that Ao-SVC GP ablation led to a significant increase in heart rate (HR) and the elimination of sinus arrest evoked by ECVS, while the vagal responses of atrial ventricular block were eliminated by the ablation of PMLGP and LSGP. Post-procedure HR increased up to 64-86% of the maximum HR of an atropine test at baseline. The median HR from Holter monitoring increased from 52.8 ± 2.1 bpm at baseline to 73.0 ± 10.4 bpm after the procedure (p = 0.012) and to 71.3 ± 10.1 bpm at the six-month follow-up (p = 0.011). Bradycardia-related symptoms disappeared in all patients at the six-month follow-up. This case series reveals the feasibility of using the ECVS-assisted sequential CNA technique and indicates the critical role of ECVS in dynamically evaluating the impact of sequential CNA on the vagal control of SAN and AVN.
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HOTAIR is a 2.2-kb long noncoding RNA (lncRNA) whose dysregulation has been linked to oncogenesis, defects in pattern formation during early development, and irregularities during the process of epithelial-to-mesenchymal transition (EMT). However, the oncogenic transformation determined by HOTAIR in vivo and its impact on chromatin dynamics are incompletely understood. Here, we generate a transgenic mouse model with doxycycline-inducible expression of human HOTAIR in the context of the MMTV-PyMT breast cancer-prone background to systematically interrogate the cellular mechanisms by which human HOTAIR lncRNA acts to promote breast cancer progression. We show that sustained high levels of HOTAIR over time increased breast metastatic capacity and invasiveness in breast cancer cells, promoting migration and subsequent metastasis to the lung. Subsequent withdrawal of HOTAIR overexpression reverted the metastatic phenotype, indicating oncogenic lncRNA addiction. Furthermore, HOTAIR overexpression altered both the cellular transcriptome and chromatin accessibility landscape of multiple metastasis-associated genes and promoted EMT. These alterations are abrogated within several cell cycles after HOTAIR expression is reverted to basal levels, indicating an erasable lncRNA-associated epigenetic memory. These results suggest that a continual role for HOTAIR in programming a metastatic gene regulatory program. Targeting HOTAIR lncRNA may potentially serve as a therapeutic strategy to ameliorate breast cancer progression.
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Neoplasias da Mama , RNA Longo não Codificante , Animais , Feminino , Humanos , Camundongos , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Proliferação de Células , Cromatina , Regulação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Camundongos Transgênicos , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Neoplasias Pulmonares/secundárioRESUMO
Although the function of microRNAs (miRNAs) during embryonic development has been intensively studied in recent years, their postnatal physiological functions remain largely unexplored due to inherent difficulties with the presence of redundant paralogs of the same seed. Thus, it is particularly challenging to uncover miRNA functions at neural circuit level since animal behaviors would need to be assessed upon complete loss of miRNA family functions. Here, we focused on the neural functions of MiR34/449 that manifests a dynamic expression pattern in the spinal cord from embryonic to postnatal stages. Our behavioral assays reveal that the loss of MiR34/449 miRNAs perturb thermally induced pain response thresholds and compromised delicate motor output in mice. Mechanistically, MiR34/449 directly target Satb1 and Satb2 to fine-tune the precise number of a sub-population of motor synergy encoder (MSE) neurons. Thus, MiR34/449 fine-tunes optimal development of Satb1/2on interneurons in the spinal cord, thereby refining explicit sensory-to-motor circuit outputs.
The spinal cord is an information superhighway that connects the body with the brain. There, circuits of neurons process information from the brain before sending commands to muscles to generate movement. Each spinal cord circuit contains many types of neurons, whose identity is defined by the set of genes that are active or 'expressed' in each cell. When a gene is turned on, its DNA sequence is copied to produce a messenger RNA (mRNA), a type of molecule that the cell then uses as a template to produce a protein. MicroRNAs (or miRNAs), on the other hand, are tiny RNA molecules that help to regulate gene expression by binding to and 'deactivating' specific mRNAs, stopping them from being used to make proteins. Mammalian cells contain thousands of types of microRNAs, many of which have unknown roles: this includes MiR34/449, a group of six microRNAs found mainly within the nervous system. By using genetic technology to delete this family from the mouse genome, Chang et al. now show that MiR34/449 has a key role in regulating spinal cord circuits. The first clue came from discovering that mice without the MiR34/449 family had unusual posture and a tendency to walk on tiptoe. The animals were also more sensitive to heat, flicking their tails away from a heat source more readily than control mice. At a finer level, the spinal cords of the mutants contained greater numbers of cells in which two genes, Satb1 and Satb2, were turned on. Compared to their counterparts in control mice, the Satb1/2-positive neurons also showed differences in the rest of the genes they expressed. In essence, these neurons had a different genetic profile in MiR34/449 mutant mice, therefore disrupting the neural circuit they belong to. Based on these findings, Chang et al. propose that in wild-type mice, the MiR34/449 family fine-tunes the expression of Satb1/2 in the spinal cord during development. In doing so, it regulates the formation of the spinal cord circuits that help to control movement. More generally, these results provide clues about how miRNAs help to determine cell identities; further studies could then examine whether other miRNAs contribute to the development and maintenance of neuronal circuits.
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Interneurônios/metabolismo , MicroRNAs/metabolismo , Neurônios Motores/metabolismo , Animais , Feminino , Masculino , Camundongos , Camundongos Knockout , Coluna Vertebral/metabolismoRESUMO
Two crucial questions in neuroscience are how neurons establish individual identity in the developing nervous system and why only specific neuron subtypes are vulnerable to neurodegenerative diseases. In the central nervous system, spinal motor neurons serve as one of the best-characterized cell types for addressing these two questions. In this review, we dissect these questions by evaluating the emerging role of regulatory microRNAs in motor neuron generation in developing embryos and their potential contributions to neurodegenerative diseases such as spinal muscular atrophy (SMA). Given recent promising results from novel microRNA-based medicines, we discuss the potential applications of microRNAs for clinical assessments of SMA disease progression and treatment.
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Sistema Nervoso Central/crescimento & desenvolvimento , Sistema Nervoso Central/fisiopatologia , Regulação da Expressão Gênica , MicroRNAs/metabolismo , Neurônios Motores/fisiologia , Atrofia Muscular Espinal/fisiopatologia , Animais , HumanosRESUMO
Progressive degeneration of motor neurons (MNs) is the hallmark of amyotrophic lateral sclerosis (ALS). Limb-innervating lateral motor column MNs (LMC-MNs) seem to be particularly vulnerable and are among the first MNs affected in ALS. Here, we report association of this differential susceptibility with reduced expression of the mir-17â¼92 cluster in LMC-MNs prior to disease onset. Reduced mir-17â¼92 is accompanied by elevated nuclear PTEN in spinal MNs of presymptomatic SOD1G93A mice. Selective dysregulation of the mir-17â¼92/nuclear PTEN axis in degenerating SOD1G93A LMC-MNs was confirmed in a double-transgenic embryonic stem cell system and recapitulated in human SOD1+/L144F-induced pluripotent stem cell (iPSC)-derived MNs. We further show that overexpression of mir-17â¼92 significantly rescues human SOD1+/L144F MNs, and intrathecal delivery of adeno-associated virus (AAV)9-mir-17â¼92 improves motor deficits and survival in SOD1G93A mice. Thus, mir-17â¼92 may have value as a prognostic marker of MN degeneration and is a candidate therapeutic target in SOD1-linked ALS. VIDEO ABSTRACT.
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Esclerose Lateral Amiotrófica/genética , Proteínas de Membrana/metabolismo , MicroRNAs/genética , Neurônios Motores/fisiologia , PTEN Fosfo-Hidrolase/metabolismo , Adenoviridae , Animais , Linhagem Celular Tumoral , Extremidades/inervação , Humanos , Células-Tronco Pluripotentes Induzidas , Injeções Espinhais , Proteínas de Membrana/genética , Camundongos , Mutação/genética , Neuroproteção , PTEN Fosfo-Hidrolase/genética , RNA Longo não Codificante , Superóxido Dismutase-1/genéticaRESUMO
Circular dichroism (CD) is an interesting phenomenon originating from the interaction of light with chiral molecules or other nanostructures lacking mirror symmetries in three-dimensional (3D) or two-dimensional (2D) space. While the observable effects of optical chirality are very weak in most of the natural materials, they can be designed and significantly enhanced in synthetic chiral structures, where the spatial symmetry of their component are broken on a nanoscale. Therefore, fabrication of composites capable of cheap, time-saving, and giant CD is desirable for the advanced optical technologies. Here, the giant CD of large-area metal nanocrescent array structures was investigated theoretically and experimentally. The largest value of the CD spectrum measured was larger than 0.5, and the CD spectrum was tuned effectively and extensively while maintaining a large peak intensity, which can be attributed to the selective excitation of the lattice surface modes (LSMs) by circularly polarized light. The analysis of the extrinsic chiral structure shows potential applications in chiral molecule sensing and polarizing imaging.
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Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in vertebrates. Thus, it is critical to uncover the molecular mechanisms of how motor axons navigate to, arborize, and innervate their peripheral muscle targets during development and degeneration. Although transgenic Hb9::GFP mouse lines have long served to visualize motor axon trajectories during embryonic development, detailed descriptions of the full spectrum of axon terminal arborization remain incomplete due to the pattern complexity and limitations of current optical microscopy. Here, we describe an improved protocol that combines light sheet fluorescence microscopy (LSFM) and robust image analysis to qualitatively and quantitatively visualize developing motor axons. This system can be easily adopted to cross genetic mutants or MN disease models with Hb9::GFP lines, revealing novel molecular mechanisms that lead to defects in motor axon navigation and arborization.
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Axônios/fisiologia , Microscopia de Fluorescência/métodos , Neurônios Motores/fisiologia , Animais , Animais Geneticamente Modificados , CamundongosRESUMO
Neuromedin U (NMU) and its structurally-related peptide, neuromedin S (NMS), are reported to regulate many physiological processes and their actions are mediated by two NMU receptors (NMUR1, NMUR2) in mammals. However, the information regarding NMU, NMS, and their receptors is limited in birds. In this study, we examined the structure, functionality, and expression of NMS, NMU, NMUR1 and NMUR2 in chickens. The results showed that: 1) chicken (c-) NMU cDNA encodes a 181-amino acid precursor, which may generate two forms of NMU peptide with 9 (cNMU-9) and 25 amino acids (cNMU-25), respectively. 2) Interestingly, two cNMS transcripts encoding two cNMS precursors of different lengths were identified from chicken pituitary, and both cNMS precursors may produce a mature cNMS peptide of 9 amino acids (cNMS-9). 3) cNMU-9, cNMU-25 and cNMS-9 could activate cNMUR1 expressed in HEK293 cells potently, as monitored by three cell-based luciferase reporter systems, indicating that cNMUR1 can act as a receptor common for cNMU and cNMS peptides, whereas cNMUR2 could be potently activated by cNMS-9, but not by cNMU-9/cNMU-25. 4) cNMU and cNMUR1 are widely expressed in chicken tissues with abundant expression noted in the gastrointestinal tract, as detected by quantitative real-time PCR, whereas cNMUR2 expression is mainly restricted to the brain and anterior pituitary, and cNMS is widely expressed in chicken tissues. Collectively, our data helps to elucidate the physiological roles of NMU/NMS peptides in birds and reveal the functional conservation and changes of NMU/NMS-NMUR axis across vertebrates.