シンポジウム
Sound of Silence：Neural restrictive silencer（NRSF/REST）Revisited |
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Neural Restrictive Silencing Factor（NRSF/REST）1995-2015
Mori Nozomu
Dept. Anatomy and Neurobiol., Nagasaki Univ. School of Med.
Brain is a tissue with higher complexity, and its complexity rely, at least in part, on a complexity in the gene regulation of a vast set of neuron-specific genes. It has been well known that many neuron-specific genes are under the control of a transcriptional repressor called Neural-restrictive silencing factor（NRSF）or RE-1 silencing transcription factor（REST）. NRSF/REST was initially identified as a transcription factor that regulates neuron-specific genes, such as SCG10 and Na+-channel type II, but its target gene repertoire is now estimated to be more than 1,000 neuron-specific genes. Since its discovery in 1995, accumulative evidence indicates that roles of NRSF/REST are not restricted to neuronal gene regulation during neural differentiation, but also are involved in stem cell regulation, brain aging, and neurodegeneration. NRSF/REST was initially thought to be expressed exclusively in non-neuronal cells and/or neuronal progenitor cells；however, recent evidence indicate that it is also expressed and play some role（s）in mature adult neurons. Recently, we came to know that several laboratories in our country are working on various aspects of NRSF/REST, and published some interesting results. Regrettably, however, those works stay independent, and researchers do not aware of other works. I think it would be beneficial if these researchers come together and have an opportunity to discuss those findings. Thus, this symposium is indicated to overview recent findings on the NRSF/REST biology, and discuss perspectives of these studies, thereby stimulating mutual interaction for potential collaboration and/or exchange ideas and materials. | | 1S7-2
Remarkable differences in NRSF/REST target genes between human ESC and ESC-derived neurons
Satoh Jun-ichi
Dept. of Bioinformatics, Meiji Pharm. Univ.
The neuron-restrictive silencer factor（NRSF）is a zinc finger transcription factor that represses neuronal gene transcription in nonneuronal cells by binding to the consensus repressor element-1（RE1）located in regulatory regions of target genes. NRSF silences the expression of a wide range of target genes involved in neuron-specific functions. Previous studies showed that aberrant regulation of NRSF plays a key role in the pathological process of human neurodegenerative diseases. However, a comprehensive set of NRSF target genes relevant to human neuronal functions have not yet been characterized. We attempted to perform genome-wide data mining from chromatin immunoprecipitation followed by deep sequencing（ChIP-Seq）datasets of NRSF binding sites in human embryonic stem cells（ESC）and the corresponding ESC-derived neurons, retrieved from the database of the ENCODE/HAIB project. By using bioinformatics tools such as Avadis NGS and MACS, we identified 2,172 NRSF target genes in ESC and 308 genes in ESC-derived neurons based on stringent criteria. Only 40 NRSF target genes overlapped between both. By motif analysis, binding regions showed an enrichment of the consensus RE1 sites in ESC, whereas they were mainly located in poorly defined non-RE1 sites in ESC-derived neurons. Molecular pathways of NRSF target genes were linked with various neuronal functions in ESC, such as neuroactive ligand-receptor interaction, CREB signaling, and axonal guidance signaling, while they were not directed to neuron-specific functions in ESC-derived neurons. Remarkable differences in ChIP-Seq-based NRSF target genes and pathways between ESC and ESC-derived neurons suggested that NRSF-mediated silencing of target genes is highly effective in human ESC but not in ESC-derived neurons（Satoh et al. Bioinform Biol Insights 7：357-368, 2013）. | | 1S7-3
Post-translational modification of Charlatan, a Drosophila NREF/REST, is required for neuron specific genes expression
Tsuda Leo，Yamasaki Yasutoyo，Lim Young-Mi
Animal Models of Aging, CAMD, National Center for Geriatrics and Gerontology
Neuronal networks in the brain are consisted with many types of neuronal cells. On the way to construct matured neuronal circuits, there are number of irreversible regulatory steps, and each steps must be tightly regulated by the expression level of neuron specific genes. Neuron-restrictive silencing factor or RE1 silencing transcription factor（NRSF/REST）has pivotal role for many kinds of target genes expression during neuronal development in mammalian cells. Recent study revealed that post-translational modification, especially the balance between ubiquitylation and de-ubiquitylation, provides rapid regulatory networks of NRSF/REST during neuronal development. In this symposium, we will present a data that the similar ubiquitylation-deubiquitylation system also plays an important role for Charlatan, a Drosophila NRSF/REST. We further reveal that the ubiquitylation leads to truncation of the C-terminal repressor domain and stabilized the N-terminal DNA-binding region of Chn. This post-translational modification of Chn drastically changed the transcriptional activities from repressor to activator. We found that the post-translational modification of Chn seems to be required for maintaining expression level of dopamine receptor gene in the mashroombody. Therefore, the dynamic changes of Chn modifications might be a determinant of the irreversible regulation of neuron specific genes expression during neuronal development. | | 1S7-4
Neuroepigenetics in negative signs of chronic pain
Ueda Hiroshi
Department of Pharmacology and Therapeutic Innovation,Nagasaki University Graduate School of Biomedical Sciences
Mechanisms underlying chronic pain are closely related to a kind of long-term memory process in the somatosensory nervous system. Emerging evidence has been accumulated that epigenetic mechanisms, such as DNA methylation and histone modifications, are engaged in the memory process of chronic pain. We have previously clarified the epigenetic regulation of pain-related genes in the primary afferent neurons underlying abnormal pain sensations and resistance to morphine in a model of peripheral nerve injury-induced chronic neuropathic pain in mice（J Neurosci, 2010）. Specifically, we have demonstrated that neuron-restrictive silencer factor（NRSF, also known as RE-1-silencing transcription factor；REST）orchestrates histone deacetylation-mediated transcriptional repression of pain-related genes to cause pathological and pharmacological dysfunction of C-fibers after nerve injury. In this symposium, I will discuss the molecular mechanisms of epigenetic gene regulation underlying chronic pain, and the therapeutic potential of epigenetically modifying compounds in the treatment of chronic pain. | | 1S7-5
Rest function in neuronal or neural crest cell lineage revealed by the conditional gene ablation
Aoki Hitomi，Kunisada Takahiro
Tissue ＆ Organ Dev. Med., Gifu Univ.
Rest also known as NRSF is a regulator of neuronal development and function. Rest null mice have embryonic lethality which prevents further investigation. To study the Rest function in vivo, we focused on the development of the neuronal and neural crest（NC）cells, both expected to require REST function. Conditional knockout（CKO）of the exon 4 of Rest encoding the CoRest binding site during the early neural development stage was carried out by using Sox1-Cre promoter. Although Rest suppressed expression of neuronal genes in vivo, Rest conditional ablation did not affect neuronal development and thus Rest is dispensable for natural neurogenesis. The morphology of neural tissues, maintenance and differentiation of neuronal progenitor cells in vivo were all normal in Rest CKO mice. While the electrical stimulations of cervical vagus nerve reduce the heart rate, blood pressure, stomach contraction etc, Rest CKO mice were found to be resistant for the stimulus induced reduction of heart rate compared to the control mice but not blood pressure and muscular contractions of stomach. While Sox1-Cre induced Rest ablation leads to in vitro-specific derepression of neuronal genes during neurogenesis, genetic ablation of Rest by Sox1-Cre does not cause any detectable morphological abnormality in the nervous system but functional defect might be caused in vagus nerve cells. Next, we used a Wnt1-Cre to specifically ablate the early progenitor cells of the developing NC lineage cells. The NCC-specific Rest CKO mice showed neonatal lethality that were characterized by gastrointestinal tract dilation, while no histological abnormalities except the thinning of the digestive tract as a consequence of the gas accumulation. The gas collected from the swollen digestive tracts of the Rest CKO mice contained high concentration of CO2. They do not have proper gastric retention and the reduction of acetylcolinesterase activity of myenteric plexus in the stomach was detected. The neonatal lethality in NCC-specific Rest CKO mice showed gastrointestinal distension phenotype caused by a failure of gut function in underdeveloped cholinergic transmission of enteric nerve system may provide a model for understanding the NCC defects in humans. These experiments indicate novel Rest phenotypes in various neuronal cell lineages. | | 1S7-6
NRSF plays an essential role in the regulation of cardiac gene expression and function
Kuwahara Koichiro，Kimura Takeshi
Department of Cardiovascular Medicine, Kyoto University Graduate School of Medicine
Alterations in the cardiac gene program affect both cardiac structure and function, and play a key role in the progression of pathological cardiac remodeling and heart failure. Among the genetic alterations in cardiac diseases, reactivation of fetal cardiac genes in adults is a consistent feature of cardiac hypertrophy and heart failure. We investigated the transcriptional regulation of fetal cardiac genes, such as geens encoding atrial and brain natriuretic peptide, and revealed a transcriptional repressor, neuron-restrictive silencer factor（NRSF）, also called repressor element-1 silencing factor（REST）, to be an important regulator of multiple fetal cardiac genes. Inhibition or deletion of NRSF in the heart leads to cardiac dysfunction and sudden arrhythmic death accompanied by re-expression of various fetal genes, including those encoding fetal ion channels, such as the HCN channels and T-type Ca2+ channels. We demonstrated that inhibition of these ion channels suppressed lethal arrhythmias and sudden arrhythmic death in mice expressing dominant-negative mutant of NRSF in a cardiac-restricted manner. Our findings indicate that NRSF plays an essential role in maintaining normal cardiac structure and function. | |
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