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Wang J, Chen S, Pan C, Li G, Tang Z. Application of Small Molecules in the Central Nervous System Direct Neuronal Reprogramming. Front Bioeng Biotechnol 2022; 10:799152. [PMID: 35875485 PMCID: PMC9301571 DOI: 10.3389/fbioe.2022.799152] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 06/09/2022] [Indexed: 11/13/2022] Open
Abstract
The lack of regenerative capacity of neurons leads to poor prognoses for some neurological disorders. The use of small molecules to directly reprogram somatic cells into neurons provides a new therapeutic strategy for neurological diseases. In this review, the mechanisms of action of different small molecules, the approaches to screening small molecule cocktails, and the methods employed to detect their reprogramming efficiency are discussed, and the studies, focusing on neuronal reprogramming using small molecules in neurological disease models, are collected. Future research efforts are needed to investigate the in vivo mechanisms of small molecule-mediated neuronal reprogramming under pathophysiological states, optimize screening cocktails and dosing regimens, and identify safe and effective delivery routes to promote neural regeneration in different neurological diseases.
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Affiliation(s)
| | | | | | - Gaigai Li
- *Correspondence: Gaigai Li, ; Zhouping Tang,
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2
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He F, Wu H, Zhou L, Lin Q, Cheng Y, Sun YE. Tet2-mediated epigenetic drive for astrocyte differentiation from embryonic neural stem cells. Cell Death Discov 2020; 6:30. [PMID: 32377393 PMCID: PMC7190615 DOI: 10.1038/s41420-020-0264-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/04/2020] [Accepted: 04/07/2020] [Indexed: 12/15/2022] Open
Abstract
DNA methylation and demethylation at CpG di-nucleotide sites plays important roles in cell fate specification of neural stem cells (NSCs). We have previously reported that DNA methyltransferases, Dnmt1and Dnmt3a, serve to suppress precocious astrocyte differentiation from NSCs via methylation of astroglial lineage genes. However, whether active DNA demethylase also participates in astrogliogenesis remains undetermined. In this study, we discovered that a Ten-eleven translocation (Tet) protein, Tet2, which was critically involved in active DNA demethylation through oxidation of 5-Methylcytosine (5mC), drove astrocyte differentiation from NSCs by demethylation of astroglial lineage genes including Gfap. Moreover, we found that an NSC-specific bHLH transcription factor Olig2 was an upstream inhibitor for Tet2 expression through direct association with the Tet2 promoter, and indirectly inhibited astrocyte differentiation. Our research not only revealed a brand-new function of Tet2 to promote NSC differentiation into astrocytes, but also a novel mechanism for Olig2 to inhibit astrocyte formation.
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Affiliation(s)
- Fei He
- Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200092 China
| | - Hao Wu
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104 USA
- Penn Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Liqiang Zhou
- Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200092 China
| | - Quan Lin
- Department of Psychiatry and Biobehavioral Sciences, Intellectual Development and Disabilities Research Center, David Geffen School of Medicine, University of California, Los Angeles, CA 90095 USA
| | - Yin Cheng
- Department of Psychiatry and Biobehavioral Sciences, Intellectual Development and Disabilities Research Center, David Geffen School of Medicine, University of California, Los Angeles, CA 90095 USA
| | - Yi E. Sun
- Shanghai Institute of Stem Cell Research and Clinical Translation, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200092 China
- Department of Psychiatry and Biobehavioral Sciences, Intellectual Development and Disabilities Research Center, David Geffen School of Medicine, University of California, Los Angeles, CA 90095 USA
- Collaborative Innovation Center for Brain Science, Tongji University, Shanghai, 200092 China
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3
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Mai HN, Nguyen LTT, Shin EJ, Kim DJ, Jeong JH, Chung YH, Lei XG, Sharma N, Jang CG, Nabeshima T, Kim HC. Astrocytic mobilization of glutathione peroxidase-1 contributes to the protective potential against cocaine kindling behaviors in mice via activation of JAK2/STAT3 signaling. Free Radic Biol Med 2019; 131:408-431. [PMID: 30592974 DOI: 10.1016/j.freeradbiomed.2018.12.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/13/2018] [Accepted: 12/21/2018] [Indexed: 02/07/2023]
Abstract
Compelling evidence indicates that oxidative stress contributes to cocaine neurotoxicity. The present study was performed to elucidate the role of the glutathione peroxidase-1 (GPx-1) in cocaine-induced kindling (convulsive) behaviors in mice. Cocaine-induced convulsive behaviors significantly increased GPx-1, p-IkB, and p-JAK2/STAT3 expression, and oxidative burdens in the hippocampus of mice. There was no significant difference in cocaine-induced p-IkB expression between non-transgenic (non-TG) and GPx-1 overexpressing transgenic (GPx-1 TG) mice, but significant differences were observed in cocaine-induced p-JAK2/STAT3 expression and oxidative stress between non-TG and GPx-1 TG mice. Cocaine-induced glial fibrillary acidic protein (GFAP)-labeled astrocytic level was significantly higher in the hippocampus of GPx-1 TG mice. Triple-labeling immunocytochemistry indicated that GPx-1-, p-STAT3-, and GFAP-immunoreactivities were co-localized in the same cells. AG490, a JAK2/STAT3 inhibitor, but not pyrrolidone dithiocarbamate, an NFκB inhibitor, significantly counteracted GPx-1-mediated protective potentials (i.e., anticonvulsant-, antioxidant-, antiapoptotic-effects). Genetic overexpression of GPx-1 significantly attenuated proliferation of Iba-1-labeled microglia induced by cocaine in mice. However, AG490 or astrocytic inhibition (by GFAP antisense oligonucleotide and α-aminoadipate) significantly increased Iba-1-labeled microglial activity and M1 phenotype microglial mRNA levels, reflecting that proinflammatory potentials were mediated by AG490 or astrocytic inhibition. This microglial activation was less pronounced in GPx-1 TG than in non-TG mice. Furthermore, either AG490 or astrocytic inhibition significantly counteracted GPx-1-mediated protective potentials. Therefore, our results suggest that astrocytic modulation between GPx-1 and JAK2/STAT3 might be one of the underlying mechanisms for protecting against convulsive neurotoxicity induced by cocaine.
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Affiliation(s)
- Huynh Nhu Mai
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Lan Thuy Ty Nguyen
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea.
| | - Dae-Joong Kim
- Department of Anatomy and Cell Biology, Medical School, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Yoon Hee Chung
- Department of Anatomy, College of Medicine, Chung-Ang University, Seoul 06974, Republic of Korea
| | - Xin Gen Lei
- Department of Animal Science, Cornell University, Ithaca, New York 14853, USA
| | - Naveen Sharma
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Aichi 470-1192, Japan; Aino University, Ibaraki 576-0012, Japan; Japanese Drug Organization of Appropriate and Research, Nagoya 468-0069, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon 24341, Republic of Korea.
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Hou L, Zhou X, Zhang C, Wang K, Liu X, Che Y, Sun F, Li H, Wang Q, Zhang D, Hong JS. NADPH oxidase-derived H 2O 2 mediates the regulatory effects of microglia on astrogliosis in experimental models of Parkinson's disease. Redox Biol 2017; 12:162-170. [PMID: 28237879 PMCID: PMC5328707 DOI: 10.1016/j.redox.2017.02.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 02/12/2017] [Accepted: 02/21/2017] [Indexed: 12/17/2022] Open
Abstract
Astrogliosis has long been recognized in Parkinson's disease (PD), the most common neurodegenerative movement disorder. However, the mechanisms of how astroglia become activated remain unclear. Reciprocal interactions between microglia and astroglia play a pivotal role in regulating the activities of astroglia. The purpose of this study is to investigate the mechanism by which microglia regulate astrogliosis by using lipopolysaccharide (LPS) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse PD models. We found that the activation of microglia preceded astroglia in the substantia nigra of mice treated with either LPS or MPTP. Furthermore, suppression of microglial activation by pharmacological inhibition or genetic deletion of NADPH oxidase (NOX2) in mice attenuated astrogliosis. The important role of NOX2 in microglial regulation of astrogliosis was further mirrored in a mixed-glia culture system. Mechanistically, H2O2, a product of microglial NOX2 activation, serves as a direct signal to regulate astrogliosis. Astrogliosis was induced by H2O2 through a process in which extracellularly generated H2O2 diffused into the cytoplasm and subsequently stimulated activation of transcription factors, STAT1 and STAT3. STAT1/3 activation regulated the immunological functions of H2O2-induced astrogliosis since AG490, an inhibitor of STAT1/3, attenuated the gene expressions of both proinflammatory and neurotrophic factors in H2O2-treated astrocyte. Our findings indicate that microglial NOX2-generated H2O2 is able to regulate the immunological functions of astroglia via a STAT1/3-dependent manner, providing additional evidence for the immune pathogenesis and therapeutic studies of PD. Microglia are capable of regulating the immunological functions of astrogliosis in Parkinson's disease. NADPH oxidase-derived H2O2 is recognized as a paracrine signal for microglial regulation of astrogliosis. Transcription factors STAT1 and STAT3 play pivotal roles in H2O2-induced astroglial activation.
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Affiliation(s)
- Liyan Hou
- Department of Occupational and Environmental Health, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China
| | - Xueying Zhou
- Department of Occupational and Environmental Health, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China
| | - Cong Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China
| | - Ke Wang
- Department of Nutrition, Second Hospital, Dalian Medical University, Dalian 116023, China
| | - Xiaofang Liu
- Department of Nutrition and Food Hygiene, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China
| | - Yuning Che
- Department of Occupational and Environmental Health, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China
| | - Fuqiang Sun
- Department of Occupational and Environmental Health, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China
| | - Huihua Li
- Department of Nutrition and Food Hygiene, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China
| | - Qingshan Wang
- Department of Occupational and Environmental Health, School of Public Health, Dalian Medical University, No. 9 W. Lvshun South Road, Dalian 116044, China.
| | - Dan Zhang
- State Key Laboratory of Natural Products and Functions, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Jau-Shyong Hong
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
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5
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Small Molecules Efficiently Reprogram Human Astroglial Cells into Functional Neurons. Cell Stem Cell 2015; 17:735-747. [PMID: 26481520 DOI: 10.1016/j.stem.2015.09.012] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 08/04/2015] [Accepted: 09/15/2015] [Indexed: 01/19/2023]
Abstract
We have recently demonstrated that reactive glial cells can be directly reprogrammed into functional neurons by a single neural transcription factor, NeuroD1. Here we report that a combination of small molecules can also reprogram human astrocytes in culture into fully functional neurons. We demonstrate that sequential exposure of human astrocytes to a cocktail of nine small molecules that inhibit glial but activate neuronal signaling pathways can successfully reprogram astrocytes into neurons in 8-10 days. This chemical reprogramming is mediated through epigenetic regulation and involves transcriptional activation of NEUROD1 and NEUROGENIN2. The human astrocyte-converted neurons can survive for >5 months in culture and form functional synaptic networks with synchronous burst activities. The chemically reprogrammed human neurons can also survive for >1 month in the mouse brain in vivo and integrate into local circuits. Our study opens a new avenue using chemical compounds to reprogram reactive glial cells into functional neurons.
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Zhao Y, Lam DH, Yang J, Lin J, Tham CK, Ng WH, Wang S. RETRACTED ARTICLE: Targeted suicide gene therapy for glioma using human embryonic stem cell-derived neural stem cells genetically modified by baculoviral vectors. Gene Ther 2011; 19:189-200. [DOI: 10.1038/gt.2011.82] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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7
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Nagarajan RP, Costello JF. Molecular epigenetics and genetics in neuro-oncology. Neurotherapeutics 2009; 6:436-46. [PMID: 19560734 PMCID: PMC3981537 DOI: 10.1016/j.nurt.2009.04.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 03/26/2009] [Accepted: 04/09/2009] [Indexed: 01/25/2023] Open
Abstract
Gliomas arise through genetic and epigenetic alterations of normal brain cells, although the exact cell of origin for each glioma subtype is unknown. The alteration-induced changes in gene expression and protein function allow uncontrolled cell division, tumor expansion, and infiltration into surrounding normal brain parenchyma. The genetic and epigenetic alterations are tumor subtype and tumor-grade specific. Particular alterations predict tumor aggressiveness, tumor response to therapy, and patient survival. Genetic alterations include deletion, gain, amplification, mutation, and translocation, which result in oncogene activation and tumor suppressor gene inactivation, or in some instances the alterations may simply be a consequence of tumorigenesis. Epigenetic alterations in brain tumors include CpG island hypermethylation associated with tumor suppressor gene silencing, gene-specific hypomethylation associated with aberrant gene activation, and genome-wide hypomethylation potentially leading to loss of imprinting, chromosomal instability, and cellular hyperproliferation. Other epigenetic alterations, such as changes in the position of histone variants and changes in histone modifications are also likely to be important in the molecular pathology of brain tumors. Given that histone deacetylases are targets for drugs that are already in clinical trial, surprisingly little is known about histone acetylation in primary brain tumors. Although a majority of epigenetic alterations are independent of genetic alterations, there is interaction on specific genes, signaling pathways and within chromosomal domains. Next-generation sequencing technology is now the method of choice for genomic and epigenome profiling, allowing more comprehensive understanding of genetic and epigenetic contributions to tumorigenesis in the brain.
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Affiliation(s)
- Raman P. Nagarajan
- grid.266102.10000000122976811Brain Tumor Research Center, Department of Neurosurgery, Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, 94143 San Francisco, California
| | - Joseph F. Costello
- grid.266102.10000000122976811Brain Tumor Research Center, Department of Neurosurgery, Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, 94143 San Francisco, California
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8
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Nagarajan RP, Costello JF. Epigenetic mechanisms in glioblastoma multiforme. Semin Cancer Biol 2009; 19:188-97. [PMID: 19429483 DOI: 10.1016/j.semcancer.2009.02.005] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 02/11/2009] [Indexed: 11/26/2022]
Abstract
Glioblastoma multiforme (GBM) is an aggressive and lethal cancer, accounting for the majority of primary brain tumors in adults. GBMs are characterized by genetic alterations large and small, affecting genes that control cell growth, apoptosis, angiogenesis, and invasion. Epigenetic alterations also affect the expression of cancer genes alone, or in combination with genetic mechanisms. For example, in each GBM, hundreds of genes are subject to DNA hypermethylation at their CpG island promoters. A subset of GBMs is also characterized by locus-specific and genome-wide decrease in DNA methylation, or DNA hypomethylation. Other epigenetic alterations, such as changes in the position of histone variants and changes in histone modifications are also likely important in the molecular pathology of GBM, but somewhat surprisingly there are very limited data about these in GBM. Alterations in histone modifications are especially important to understand, given that histone deacetylases are targets for drugs that are in clinical trial for GBMs. The technological wave of next-generation sequencing will accelerate GBM epigenome profiling, allowing the direct integration of DNA methylation, histone modification and gene expression profiles. Ultimately, genomic and epigenomic data should provide new predictive markers of response and lead to more effective therapies for GBM.
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Affiliation(s)
- Raman P Nagarajan
- Brain Tumor Research Center, Department of Neurosurgery, Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94143, USA
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9
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Perng MD, Wen SF, Gibbon T, Middeldorp J, Sluijs J, Hol EM, Quinlan RA. Glial fibrillary acidic protein filaments can tolerate the incorporation of assembly-compromised GFAP-delta, but with consequences for filament organization and alphaB-crystallin association. Mol Biol Cell 2008; 19:4521-33. [PMID: 18685083 DOI: 10.1091/mbc.e08-03-0284] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The glial fibrillary acidic protein (GFAP) gene is alternatively spliced to give GFAP-alpha, the most abundant isoform, and seven other differentially expressed transcripts including GFAP-delta. GFAP-delta has an altered C-terminal domain that renders it incapable of self-assembly in vitro. When titrated with GFAP-alpha, assembly was restored providing GFAP-delta levels were kept low (approximately 10%). In a range of immortalized and transformed astrocyte derived cell lines and human spinal cord, we show that GFAP-delta is naturally part of the endogenous intermediate filaments, although levels were low (approximately 10%). This suggests that GFAP filaments can naturally accommodate a small proportion of assembly-compromised partners. Indeed, two other assembly-compromised GFAP constructs, namely enhanced green fluorescent protein (eGFP)-tagged GFAP and the Alexander disease-causing GFAP mutant, R416W GFAP both showed similar in vitro assembly characteristics to GFAP-delta and could also be incorporated into endogenous filament networks in transfected cells, providing expression levels were kept low. Another common feature was the increased association of alphaB-crystallin with the intermediate filament fraction of transfected cells. These studies suggest that the major physiological role of the assembly-compromised GFAP-delta splice variant is as a modulator of the GFAP filament surface, effecting changes in both protein- and filament-filament associations as well as Jnk phosphorylation.
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Affiliation(s)
- Ming-Der Perng
- School of Biological and Biomedical Sciences, The University of Durham, Durham DH1 3LE, United Kingdom
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Liu L, van Groen T, Kadish I, Tollefsbol TO. DNA methylation impacts on learning and memory in aging. Neurobiol Aging 2007; 30:549-60. [PMID: 17850924 PMCID: PMC2656583 DOI: 10.1016/j.neurobiolaging.2007.07.020] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 06/19/2007] [Accepted: 07/24/2007] [Indexed: 12/20/2022]
Abstract
Learning and memory are two of the fundamental cognitive functions that confer us the ability to accumulate knowledge from our experiences. Although we use these two mental skills continuously, understanding the molecular basis of learning and memory is very challenging. Methylation modification of DNA is an epigenetic mechanism that plays important roles in regulating gene expression, which is one of the key processes underlying the functions of cells including neurons. Interestingly, a genome-wide decline in DNA methylation occurs in the brain during normal aging, which coincides with a functional decline in learning and memory with age. It has been speculated that DNA methylation in neurons might be involved in memory coding. However, direct evidence supporting the role of DNA methylation in memory formation is still under investigation. This particular function of DNA methylation has not drawn wide attention despite several important studies that have provided supportive evidence for the epigenetic control of memory formation. To facilitate further exploration of the epigenetic basis of memory function, we will review existing studies on DNA methylation that are related to the development and function of the nervous system. We will focus on studies illustrating how DNA methylation regulates neural activities and memory formation via the control of gene expression in neurons, and relate these studies to various age-related neurological disorders that affect cognitive functions.
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Affiliation(s)
- Liang Liu
- Department of Biology, University of Alabama at Birmingham, 175 Campbell Hall, 1300 University Boulevard, Birmingham, AL 35294-1170, USA.
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11
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Zhang F, Pomerantz JH, Sen G, Palermo AT, Blau HM. Active tissue-specific DNA demethylation conferred by somatic cell nuclei in stable heterokaryons. Proc Natl Acad Sci U S A 2007; 104:4395-400. [PMID: 17360535 PMCID: PMC1838613 DOI: 10.1073/pnas.0700181104] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA methylation is among the most stable epigenetic marks, ensuring tissue-specific gene expression in a heritable manner throughout development. Here we report that differentiated mesodermal somatic cells can confer tissue-specific changes in DNA methylation on epidermal progenitor cells after fusion in stable multinucleate heterokaryons. Myogenic factors alter regulatory regions of genes in keratinocyte cell nuclei, demethylating and activating a muscle-specific gene and methylating and silencing a keratinocyte-specific gene. Because these changes occur in the absence of DNA replication or cell division, they are mediated by an active mechanism. Thus, the capacity to transfer epigenetic changes to other nuclei is not limited to embryonic stem cells and oocytes but is also a property of highly specialized mammalian somatic cells. These results suggest the possibility of directing the reprogramming of readily available postnatal human progenitor cells toward specific tissue cell types.
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Affiliation(s)
- Fan Zhang
- *Baxter Laboratory in Genetic Pharmacology, Departments of Microbiology and Immunology, and
| | - Jason H. Pomerantz
- *Baxter Laboratory in Genetic Pharmacology, Departments of Microbiology and Immunology, and
- Division of Plastic and Reconstructive Surgery, Department of Surgery, University of California, San Francisco, CA 94143-0932
- To whom correspondence may be addressed. E-mail:
or
| | - George Sen
- *Baxter Laboratory in Genetic Pharmacology, Departments of Microbiology and Immunology, and
- Department of Dermatology, Stanford University School of Medicine, Stanford, CA 94305-3175; and
| | - Adam T. Palermo
- *Baxter Laboratory in Genetic Pharmacology, Departments of Microbiology and Immunology, and
| | - Helen M. Blau
- *Baxter Laboratory in Genetic Pharmacology, Departments of Microbiology and Immunology, and
- To whom correspondence may be addressed. E-mail:
or
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Cebolla B, Vallejo M. Nuclear factor-I regulates glial fibrillary acidic protein gene expression in astrocytes differentiated from cortical precursor cells. J Neurochem 2006; 97:1057-70. [PMID: 16606365 DOI: 10.1111/j.1471-4159.2006.03804.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The elucidation of the transcriptional mechanisms that regulate glial fibrillary acidic protein (GFAP) gene expression is important for the understanding of the molecular mechanisms that control astrocyte differentiation during brain development. We investigated regulatory elements located in a proximal region of the GFAP promoter, important for expression in cortical precursor cells differentiating into astrocytes. One of these elements recognizes transcription factors of the nuclear factor-I family (NFI). We found that, in primary cultures of cortical cells, NFI occupies the GFAP promoter prior to the induction of astrocyte differentiation. In the developing cerebral cortex, the onset of expression of NFI coincides chronologically with the beginning of astrocytogenesis. Mutational analysis of the GFAP gene and transfections in primary cortical precursors show that inhibition of binding of NFI to the GFAP promoter results in decreased levels of transcriptional activity and is required for the synergistic stimulation of the GFAP promoter by the astrogenic agents, pituitary adenylate cyclase-activating polypeptide and ciliary neurotrophic factor, which in combination enhance astrocyte differentiation to generate astrocytes with longer processes. Thus, NFI appears to be an important factor for the integration of astrogenic stimuli in the developing central nervous system.
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Affiliation(s)
- Beatriz Cebolla
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid, Madrid, Spain
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Ehrlich M. The controversial denouement of vertebrate DNA methylation research. BIOCHEMISTRY (MOSCOW) 2005; 70:568-75. [PMID: 15948710 DOI: 10.1007/s10541-005-0150-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The study of the biological role of DNA methylation in vertebrates has involved considerable controversy. Research in this area has proceeded well despite the complexity of the subject and the difficulties in establishing biological roles, some of which are summarized in this review. Now there is justifiably much more interest in DNA methylation than previously, and many more laboratories are engaged in this research. The results of numerous studies indicate that some tissue-specific differences in vertebrate DNA methylation help maintain patterns of gene expression or are involved in fine-tuning or establishing expression patterns. Therefore, vertebrate DNA methylation cannot just be assigned a role in silencing transposable elements and foreign DNA sequences, as has been suggested. DNA methylation is clearly implicated in modulating X chromosome inactivation and in establishing genetic imprinting. Also, hypermethylation of CpG-rich promoters of tumor suppressor genes in cancer has a critical role in downregulating expression of these genes and thus participating in carcinogenesis. The complex nature of DNA methylation patterns extends to carcinogenesis because global DNA hypomethylation is found in the same cancers displaying hypermethylation elsewhere in the genome. A wide variety of cancers display both DNA hypomethylation and hypermethylation, and either of these types of changes can be significantly associated with tumor progression. These findings and the independence of cancer-linked DNA hypomethylation from cancer-linked hypermethylation strongly implicate DNA hypomethylation, as well as hypermethylation, in promoting carcinogenesis. Furthermore, various DNA demethylation methodologies have been shown to increase the formation of certain types of cancers in animals, and paradoxically, DNA hypermethylation can cause carcinogenesis in other model systems. Therefore, there is a need for caution in the current use of demethylating agents as anti-cancer drugs. Nonetheless, DNA demethylation therapy clearly may be very useful in cases where better alternatives do not exist.
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Affiliation(s)
- M Ehrlich
- Human Genetics Program SL31, Tulane Medical School, New Orleans, LA 70112, USA.
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14
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Pérez-Villamil B, Mirasierra M, Vallejo M. The homeoprotein Alx3 contains discrete functional domains and exhibits cell-specific and selective monomeric binding and transactivation. J Biol Chem 2004; 279:38062-71. [PMID: 15226305 DOI: 10.1074/jbc.m400800200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Alx3 is a paired class aristaless-like homeoprotein expressed during embryonic development. Transcriptional transactivation by aristaless-like proteins has been associated with cooperative dimerization upon binding to artificially generated DNA consensus sequences known as P3 sites, but natural target sites in genes regulated by Alx3 are unknown. We report the cloning of a cDNA encoding the rat homolog of Alx3, and we characterize the protein domains that are important for transactivation, dimerization, and binding to DNA. Two proline-rich domains located amino-terminal to the homeodomain (Pro1 and Pro2) are necessary for Alx3-dependent transactivation, whereas another one (Pro3) located in the carboxyl terminus is dispensable but contributes to enhance the magnitude of the response. We confirmed that transcriptional activity of Alx3 from a P3 site correlates with cooperative dimerization upon binding to DNA. However, Alx3 was found to bind selectively to non-P3-related TAAT-containing sites present in the promoter of the somatostatin gene in a specific manner that depends on the nuclear protein environment. Cell-specific transactivation elicited by Alx3 from these sites could not be predicted from in vitro DNA-binding experiments by using recombinant Alx3. In addition, transactivation did not depend on cooperative dimerization upon binding to cognate somatostatin DNA sites. Our data indicate that the paradigm according to which Alx3 must act homodimerically via cooperative binding to P3-like sites is insufficient to explain the mechanism of action of this homeoprotein to regulate transcription of natural target genes. Instead, Alx3 undergoes restrictive or permissive interactions with nuclear proteins that determine its binding to and transactivation from TAAT target sites selected in a cell-specific manner.
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Affiliation(s)
- Beatriz Pérez-Villamil
- Reproductive Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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15
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Mastronardi FG, Min W, Wang H, Winer S, Dosch M, Boggs JM, Moscarello MA. Attenuation of Experimental Autoimmune Encephalomyelitis and Nonimmune Demyelination by IFN-β plus Vitamin B12: Treatment to Modify Notch-1/Sonic Hedgehog Balance. THE JOURNAL OF IMMUNOLOGY 2004; 172:6418-26. [PMID: 15128833 DOI: 10.4049/jimmunol.172.10.6418] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Interferon-beta is a mainstay therapy of demyelinating diseases, but its effects are incomplete in human multiple sclerosis and several of its animal models. In this study, we demonstrate dramatic improvements of clinical, histological, and laboratory parameters in in vivo mouse models of demyelinating disease through combination therapy with IFN-beta plus vitamin B(12) cyanocobalamin (B(12)CN) in nonautoimmune primary demyelinating ND4 (DM20) transgenics, and in acute and chronic experimental autoimmune encephalomyelitis in SJL mice. Clinical improvement (p values <0.0001) was paralleled by near normal motor function, reduced astrocytosis, and reduced demyelination. IFN-beta plus B(12)CN enhanced in vivo and in vitro oligodendrocyte maturation. In vivo and in vitro altered expression patterns of reduced Notch-1 and enhanced expression of sonic hedgehog and its receptor were consistent with oligodendrocyte maturation and remyelination. IFN-beta-B(12)CN combination therapy may be promising for the treatment of multiple sclerosis.
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MESH Headings
- Acute Disease
- Animals
- Brain/drug effects
- Brain/metabolism
- Cell Line
- Chronic Disease
- Demyelinating Diseases/genetics
- Demyelinating Diseases/metabolism
- Demyelinating Diseases/prevention & control
- Drug Synergism
- Drug Therapy, Combination
- Encephalomyelitis, Autoimmune, Experimental/genetics
- Encephalomyelitis, Autoimmune, Experimental/metabolism
- Encephalomyelitis, Autoimmune, Experimental/prevention & control
- Female
- Hedgehog Proteins
- Humans
- Interferon-beta/therapeutic use
- Mice
- Mice, Inbred Strains
- Mice, Transgenic
- Oligodendroglia/cytology
- Oligodendroglia/drug effects
- Oligodendroglia/metabolism
- Peptide Fragments/biosynthesis
- Receptor, Notch1
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/metabolism
- Stem Cells/drug effects
- Stem Cells/metabolism
- Trans-Activators/biosynthesis
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription Factors
- Vitamin B 12/therapeutic use
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Affiliation(s)
- Fabrizio G Mastronardi
- Department of Structural Biology and Biochemistry, Hospital for Sick Children, Toronto, Ontario, Canada
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16
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Ehrlich M. Expression of various genes is controlled by DNA methylation during mammalian development. J Cell Biochem 2003; 88:899-910. [PMID: 12616529 DOI: 10.1002/jcb.10464] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Despite thousands of articles about 5-methylcytosine (m(5)C) residues in vertebrate DNA, there is still controversy concerning the role of genomic m(5)C in normal vertebrate development. Inverse correlations between expression and methylation are seen for many gene regulatory regions [Heard et al., 1997; Attwood et al., 2002; Plass and Soloway, 2002] although much vertebrate DNA methylation is in repeated sequences [Ehrlich et al., 1982]. At the heart of this debate is whether vertebrate DNA methylation has mainly a protective role in limiting expression of foreign DNA elements and endogenous transposons [Walsh and Bestor, 1999] or also is important in the regulation of the expression of diverse vertebrate genes involved in differentiation [Attwood et al., 2002]. Enough thorough studies have now been reported to show that many tissue- or development-specific changes in methylation at vertebrate promoters, enhancers, or insulators regulate expression and are not simply inconsequential byproducts of expression differences. One line of evidence comes from mutants with inherited alterations in genes encoding DNA methyltransferases and from rodents or humans with somatically acquired changes in DNA methylation that illustrate the disease-producing effects of abnormal methylation. Another type of evidence derives from studies of in vivo correlations between tissue-specific changes in DNA methylation and gene expression coupled with experiments demonstrating cause-and-effect associations between DNA hyper- or hypomethylation and gene expression. In this review, I summarize some of the strong evidence from both types of studies. Taken together, these studies demonstrate that DNA methylation in mammals modulates expression of many genes during development, causing major changes in or important fine-tuning of expression. Also, I discuss previously established and newly hypothesized mechanisms for this epigenetic control.
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Affiliation(s)
- Melanie Ehrlich
- Program in Human Genetics, Department of Biochemistry, and Tulane Cancer Center, Tulane Medical School, New Orleans, LA 70112, USA.
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17
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Calabrese V, Copani A, Testa D, Ravagna A, Spadaro F, Tendi E, Nicoletti VG, Giuffrida Stella AM. Nitric oxide synthase induction in astroglial cell cultures: effect on heat shock protein 70 synthesis and oxidant/antioxidant balance. J Neurosci Res 2000; 60:613-22. [PMID: 10820432 DOI: 10.1002/(sici)1097-4547(20000601)60:5<613::aid-jnr6>3.0.co;2-8] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Glial cells in the nervous system can produce nitric oxide in response to cytokines. This production is mediated by the inducible isoform of nitric oxide synthase. Radical oxygen species (ROS) and nitric oxide (NO) derivatives have been claimed to play a crucial role in many different processes, both physiological such as neuromodulation, synaptic plasticity, response to glutamate, and pathological such as ischemia and various neurodegenerative disorders. In the present study we investigated the effects of NO synthase (iNOS) induction in astrocyte cultures on the synthesis of heat shock proteins, the activity of respiratory chain complexes and the oxidant/antioxidant balance. Treatment of astrocyte cultures for 18 hr with LPS and INFgamma produced a dose dependent increase of iNOS associated with an increased synthesis of hsp70 stress proteins. This effect was abolished by the NO synthase inhibitor L-NMMA and significantly decreased by addition of SOD/CAT in the medium. Time course experiments showed that iNOS induced protein expression increased significantly by 2 hr after treatment with LPS and INFgamma and reached a plateau at 18 hr; hsp70 protein synthesis peaked around 18 and 36 hr after the same treatment. Addition to astrocytes of the NO donor sodium nitroprusside resulted in a dose dependent increase in hsp70 protein that was comparable to that found after a mild heat shock. Additionally, a decrease in cytochrome oxidase activity, a marked decrease in ATP and protein sulfhydryl contents, an increase in the activity of the antioxidant enzymes mt-SOD and catalase were found which were abolished by L-NMMA. These findings suggest the importance of mitochondrial energy impairment as a critical determinant of the susceptibility of astrocytes to neurotoxic processes and point to a possible pivotal role of hsp70 in the signalling pathways of stress tolerance.
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Affiliation(s)
- V Calabrese
- Biochemistry, Faculty of Medicine, University of Catania, Italy.
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18
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Barresi V, Condorelli DF, Giuffrida Stella AM. GFAP gene methylation in different neural cell types from rat brain. Int J Dev Neurosci 1999; 17:821-8. [PMID: 10593618 DOI: 10.1016/s0736-5748(99)00059-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
It is generally believed that specific demethylation processes take place in the promoter of tissue-specific genes during development. It has been suggested that hypomethylation of the -1500/-1100 domain of the 5' flanking regulatory region of the rat glial fibrillary acidic protein gene may be specific for neuroectodermal derivatives such as neurons and astrocytes. In the present work the methylation status of one of those seven CG sites (the -1176) of the 'neuroectoderm-specific domain' was analyzed. In agreement with the neuroectoderm hypothesis, the -1176 site is highly demethylated in astroglial, oligodendroglial and neuronal cells, but heavily methylated in microglial and fibroblast cells. The three different glial population are derived from the same tissue (cerebral hemispheres of newborn rats) but have a different embryological origin: oligodendrocytes and astrocytes originate from neuroectoderm, while microglia is of mesodermal origin. It is not clear if GFAP-negative neuronal cells maintain such demethylation in the advanced stage of maturation or if they undergo a second phase of de novo methylation. In order to clarify this point we used a subcellular fractionation method which allowed us to separate two different nuclear populations from adult rat cerebral hemispheres: one enriched in neuronal nuclei (called N1) and the other enriched in glial nuclei (N2). A higher methylation level of the -1176 site was detected in the N1 fraction, suggesting the GFAP gene undergo a de novo methylation process during neuronal maturation. This observation is in agreement with recent results showing a de novo methylation of the -1176 site during postnatal brain development. We hypothesize that a DNA demethylation process takes place in neuroectodermal precursor cells and that the -1176 site persists demethylated at the earlier stages of neuronal differentiation (immature neurons) and becomes fully methylated at more advanced stages of differentiation.
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Affiliation(s)
- V Barresi
- Dipartimento di Scienze Chimiche, Facoltà di Medicina, Università di Catania, Italy
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19
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Condorelli DF, Nicoletti VG, Barresi V, Conticello SG, Caruso A, Tendi EA, Giuffrida Stella AM. Structural features of the rat GFAP gene and identification of a novel alternative transcript. J Neurosci Res 1999; 56:219-28. [PMID: 10336251 DOI: 10.1002/(sici)1097-4547(19990501)56:3<219::aid-jnr1>3.0.co;2-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The glial fibrillary acidic protein (GFAP) is expressed in a cell-specific manner and represents the major subunit of intermediate filaments of astroglial cells. The knowledge of the gene structure is an important step for further understanding the mechanisms of cell-specific expression. In the present study, we report the complete sequence of the rat GFAP gene and provide evidence for the existence, in the rat brain, of a novel alternative transcript. Since three different transcripts, indicated as GFAPalpha, beta, and gamma, have been previously reported (Feinstein et al. [1992] J. Neurosci. Res. 32:1-14; Zelenika et al. [1995] Mol. Brain Res. 30:251-258), we called this novel mRNA isoform GFAPdelta. It is generated by the alternative splicing of a novel exon located in the classic seventh intron. This alternative exon (called VII+) contains a 101-bp coding sequence in frame with exon VII and interrupted by a stop codon TAA at position +5451. Therefore, the novel GFAPdelta transcript encodes for an hypothetical GFAP where the forty-two carboxy-terminal amino acids encoded by exon VIII and IX are replaced by thirty-three amino acids encoded by exon VII+. Northern blot analysis with a specific probe for exon VII+ revealed a 4.2-kb mRNA, expressed in several brain areas, but absent in extracerebral tissues (lung, heart, kidney, liver, spleen). The previously discovered GFAP isoforms (alpha, beta, and gamma) produce hypothetical translation products differing in the amino-terminal Head domain. The present data suggest, for the first time, the possible existence of GFAP isoforms differing in the carboxy-terminal Tail domain.
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Affiliation(s)
- D F Condorelli
- Institute of Biochemistry, Faculty of Medicine, University of Catania, Italy.
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20
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Condorelli DF, Nicoletti VG, Dell'Albani P, Barresi V, Caruso A, Conticello SG, Belluardo N, Giuffrida Stella AM. GFAPbeta mRNA expression in the normal rat brain and after neuronal injury. Neurochem Res 1999; 24:709-14. [PMID: 10344602 DOI: 10.1023/a:1021016828704] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
GFAPbeta mRNA is an alternative transcript of the glial fibrillary acidic protein (GFAP) gene, whose transcriptional start site is located 169 nucleotides upstream to the classical GFAPalpha mRNA. By an RT-PCR method with primers on separate exons, we were able to confirm the presence of GFAP transcripts with a longer 5' untranslated region in all the examined areas of rat brain and in primary cultures of astroglial cells. Northern blot analysis, using an oligoprobe specific for the 5' region of GFAPbeta, revealed a single hybridization band of 2.9 kb in all the brain regions examined and in primary cultures of astroglial cells. The availability of the quantitative Northern blot assay allowed further studies on the regulation of GFAPbeta expression in vivo. Since it is well-known that neuronal brain injury is one of the most powerful inducers of GFAP, we examined the expression of GFAPalpha and beta after a neurotoxic lesion in the rat hippocampus. Results obtained show a parallel increase in both GFAP transcripts with an identical time-course, suggesting that regulatory regions of the gene influence in similar way the rate of transcription at the two different start sites (alpha and beta) or that a similar post-transcriptional mechanism is involved in regulating both mRNA isoforms.
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Affiliation(s)
- D F Condorelli
- Institute of Biochemistry, Faculty of Medicine, University of Catania, Italy.
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21
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Condorelli DF, Trovato-Salinaro A, Spinella F, Valvo S, Saponara R, Giuffrida S. Rapid touchdown PCR assay for the molecular diagnosis of spinocerebellar ataxia type 2. INTERNATIONAL JOURNAL OF CLINICAL & LABORATORY RESEARCH 1998; 28:174-8. [PMID: 9801928 DOI: 10.1007/s005990050039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Seven different chromosomal loci, designated SCA1 to SCA7 (spinocerebellar ataxias), have been identified as responsible for autosomal dominant cerebellar ataxias. Five genes (SCA1, 2, 3, 6, 7) have been cloned to date and show a single type of mutation, an unstable expansion of a CAG repeat coding for a polyglutamine stretch in the corresponding protein. We describe an improved polymerase chain reaction assay, based on a touchdown protocol, for the diagnosis of spinocerebellar ataxia type 2. This method produces an efficient amplification of both normal and pathological alleles and no radioactive labelling is necessary to observe the amplification products. The pathological alleles are identified by a simple non-denaturing polyacrylamide electrophoretic separation followed by ethidium bromide staining. A comparison of this technique with previously reported methods confirmed its utility for the rapid molecular diagnosis of spinocerebellar ataxia type 2. We found that the spinocerebellar ataxia type 2 mutation is responsible for 88% of the examined autosomal dominant cerebellar ataxia type 1 families in our territory (eastern Sicily). With the rapid touchdown polymerase chain reaction method, the trinucleotide expansion was also observed in 2 ataxic patients without family history of the disease, suggesting the necessity for analysis of spinocerebellar ataxia type 2 expansion even in sporadic patients.
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Affiliation(s)
- D F Condorelli
- Institute of Biochemistry, Faculty of Medicine, University of Catania, Italy
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22
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Nicoletti VG, Caruso A, Tendi EA, Privitera A, Console A, Calabrese V, Spadaro F, Ravagna A, Copani A, Stella AM. Effect of nitric oxide synthase induction on the expression of mitochondrial respiratory chain enzyme subunits in mixed cortical and astroglial cell cultures. Biochimie 1998; 80:871-81. [PMID: 9893946 DOI: 10.1016/s0300-9084(00)88882-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the present study we evaluated the effects of NO synthase (NOS) induction on the regulation of cytochrome c oxidase (CO) and F0F1-ATPase subunit expression in astroglial and mixed cortical cell cultures. In mixed cortical cell cultures, 18 h of treatment with lipopolysaccharide (LPS, 0.1 microgram/mL) plus interferon-gamma (INF-gamma, 10 U/mL) caused an increase of mRNAs for CO-I, F0F1-ATPase 6 and also for iNOS at 20 DIV. The induction of both CO-I and F0F1-ATPase 6 was abolished by the NOS inhibitor N-monomethyl-L-arginine (NMMA) or by the enzymatic scavenger superoxide dismutase/catalase (SOD/CAT). In primary astroglial cell cultures, treatment for 18 h with increasing concentrations of LPS and INF gamma, produced an increase in the amount of mitochondrial encoded CO-I and -II subunits, with no significant modifications of nuclear encoded subunit IV. An increase was also observed at level of transcription for CO-I and -II, and F0F1-ATPase 6 mRNAs. These effects were abolished by addition of NMMA or SOD/CAT. mRNA induction of CO-I was higher in mixed cortical than in astroglial cell cultures while that of F0F1-ATPase 6 was similar in both cell types. These results suggest that the expression of mitochondrial encoded subunits (CO-I, CO-II and F0F1-ATPase 6) is up-regulated in response to oxygen and NO reactive species. The activity of cytochrome c oxidase decreased after LPS/INF gamma treatment in both astroglial and mixed cortical cultures. The activity of ATP synthase was unmodified, while ATP content drastically decreased after LPS/INF gamma treatment, in both astroglial and mixed cortical cultures. The enzymatic activities of catalase and Mn-SOD (mitochondrial) showed a significant increase after LPS/INF gamma treatment, which was abolished by NMMA.
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Affiliation(s)
- V G Nicoletti
- Institute of Biochemistry, Faculty of Medicine, University of Catania, Italy
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23
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Sakai H, Nakashima S, Yoshimura S, Nishimura Y, Sakai N, Nozawa Y. Molecular cloning of a cDNA encoding a serine protease homologous to complement C1s precursor from rat C6 glial cells and its expression during glial differentiation. Gene 1998; 209:87-94. [PMID: 9524231 DOI: 10.1016/s0378-1119(98)00015-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A cDNA of rat C6 cells was cloned, which was considered to be involved in glial cell differentiation induced by dibutyryl cyclic AMP and theophylline. The cDNA fragment of the gene, termed r-gsp, was originally isolated by mRNA fingerprinting using arbitrarily primed polymerase chain reaction, and was homologous to complement C1s precursors of hamster and human. It encodes a protein of 694 amino acids containing a potential signal peptide, an epidermal growth factor-like domain surrounded by two complement C1r/C1s-related repeats, and a putative trypsin-type serine protease domain. Since the hamster and human C1s, and a protein encoded by r-gsp shared high similarity in primary structure, the r-gsp gene could encode a C1s counterpart of the rat. Messenger RNA expression of this gene was markedly increased during cyclic AMP-induced glial cell differentiation. Its expression profile was well correlated with those of glial fibrillary acidic protein (GFAP) and S100B, which are known as glial differentiation markers. It was, moreover, observed that the r-gsp expression in brain increased considerably after birth, like those of S100B and GFAP. The results presented here suggest that the rat C1s gene would be also implicated in glial differentiation besides the complement cascade.
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Affiliation(s)
- H Sakai
- Department of Neurosurgery, Gifu University School of Medicine, Tsukasamachi-40, Gifu 500, Japan
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24
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Bonni A, Sun Y, Nadal-Vicens M, Bhatt A, Frank DA, Rozovsky I, Stahl N, Yancopoulos GD, Greenberg ME. Regulation of gliogenesis in the central nervous system by the JAK-STAT signaling pathway. Science 1997; 278:477-83. [PMID: 9334309 DOI: 10.1126/science.278.5337.477] [Citation(s) in RCA: 779] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A mechanism by which members of the ciliary neurotrophic factor (CNTF)-leukemia inhibitory factor cytokine family regulate gliogenesis in the developing mammalian central nervous system was characterized. Activation of the CNTF receptor promoted differentiation of cerebral cortical precursor cells into astrocytes and inhibited differentiation of cortical precursors along a neuronal lineage. Although CNTF stimulated both the Janus kinase-signal transducer and activator of transcription (JAK-STAT) and Ras-mitogen-activated protein kinase signaling pathways in cortical precursor cells, the JAK-STAT signaling pathway selectively enhanced differentiation of these precursors along a glial lineage. These findings suggest that cytokine activation of the JAK-STAT signaling pathway may be a mechanism by which cell fate is controlled during mammalian development.
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Affiliation(s)
- A Bonni
- Division of Neuroscience, Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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25
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Abstract
One of the most prevalent products of oxygen radical injury in DNA is 8-hydroxyguanosine. Cells must be able to withstand damage by oxygen radicals and possess specific repair mechanisms that correct this oxidative lesion. However, when these defenses are oversaturated, such as under conditions of high oxidative stress, or when repair is inefficient, the miscoding potential of this lesion can result in mutations in the mammalian genome. In addition to causing genetic changes, active oxygen species can lead to epigenetic alterations in DNA methylation, without changing the DNA base sequence. Such changes in DNA methylation patterns can strongly affect the regulation of expression of many genes. Although DNA methylation patterns have been found to be altered during carcinogenesis, little is known about the mechanism(s) that produce this loss of epigenetic controls of gene expression in tumors. Replacement of guanine with the oxygen radical adduct 8-hydroxyguanine profoundly alters methylation of adjacent cytosines, suggesting a role for oxidative injury in the formation of aberrant DNA methylation patterns during carcinogenesis. In this paper, we review both the genetic and epigenetic mechanisms of oxidative DNA damage and its association with the carcinogenic process, with special emphasis on the influence of free radical injury on DNA methylation.
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Affiliation(s)
- S Cerda
- Department of Medicine, Northwestern University Medical School, Chicago, IL 60611, USA
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26
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Teter B, Rozovsky I, Krohn K, Anderson C, Osterburg H, Finch C. Methylation of the glial fibrillary acidic protein gene shows novel biphasic changes during brain development. Glia 1996; 17:195-205. [PMID: 8840161 DOI: 10.1002/(sici)1098-1136(199607)17:3<195::aid-glia2>3.0.co;2-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The gene for glial fibrillary acidic protein (GFAP) was analyzed in the rat for developmental changes in methylation of cytosine at CpG sequences as a correlate of the onset of GFAP mRNA expression and for the effect of methylation on GFAP promoter activity. The methylation of nine CpG sites in the GFAP promoter and ten sites in exon 1 was analyzed in F344 rats by a quantitative application of ligation-mediated polymerase chain reaction. Whole rat brain poly(A)+ RNA showed an exponential increase of GFAP mRNA after embryo day 14 that reached stable adult levels by postnatal day 10. During development, only the seven CpG sites in the far-upstream promoter showed large changes in methylation; these sites constitute the brain-specific domain of methylation described in adult rats (Teter et al: J Neurosci Res 39:680, 1994). These seven CpG sites showed a cycle of demethylation during the onset of GFAP transcription in the embryo (between embryonic day 14 and postnatal day 10) followed by remethylation at later postnatal ages when GFAP mRNA remains prevalent. The minimum levels of methylation across these CpG sites displayed a gradient with the lowest minima at the 3' sites. This demethylation/remethylation cycle is a novel phenomenon in DNA methylation during perinatal development. The demethylation/remethylation cycle during development was also shown by the opposite-strand cytosines. Two cytosines in this region that are conserved in rat and mouse also undergo the same demethylation/remethylation cycle in the mouse GFAP gene during development, implying evolutionary conservation and functional significance. As a further test of functional significance, a Luciferase reporter gene assay was evaluated in primary cultured astrocytes; the activity of the GFAP promoter was reduced when it was methylated at one or all CpG sites. Therefore, the GFAP promoter may be activated in rodent development by transient demethylation of a conserved brain-specific methylation domain.
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Affiliation(s)
- B Teter
- Neurogerontology Division, Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191, USA
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27
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Teter B, Finch CE, Condorelli DF. DNA methylation in the glial fibrillary acidic protein gene: map of CpG methylation sites and summary of analysis by restriction enzymes and by LMPCR. J Neurosci Res 1994; 39:708-9. [PMID: 7897705 DOI: 10.1002/jnr.490390611] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- B Teter
- Neurogerontology Division, Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191
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28
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Teter B, Osterburg HH, Anderson CP, Finch CE. Methylation of the rat glial fibrillary acidic protein gene shows tissue-specific domains. J Neurosci Res 1994; 39:680-93. [PMID: 7897703 DOI: 10.1002/jnr.490390609] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The gene for glial fibrillary acidic protein (GFAP) was compared for CpG sites that are potential locations of methylated cytosine (mC). GFAP sequences in the 5'-upstream promoter and in exon 1 of rat, mouse, and human showed extensive similarity in the locations of CpG sites in the promoter and in exon 1, implying conservation. The methylation of mC at 9 CpG sites in the promoter and 10 sites in exon 1 was analyzed in F344 male rats by a quantitative application of ligation-mediated polymerase chain reaction (LMPCR). CpG sites with varying mC in different tissues were found in the GFAP promoter and in a CpG island in exon 1. In the brain, the promoter had about 40% less mC than in testis and liver. The degree of methylation varied strikingly between adjacent sites within and between tissues. Testis GFAP exon 1 had a gradient of mC from 5' to 3' across the exon that was absent in liver, brain, and cultured neurons and astrocytes. Among brain regions, the hippocampus had 10-40% less mC at 12 CpG sites than in hypothalamus; the other sites (7/19) showed smaller differences between these brain regions. In DNA from primary cultures, astrocytes had slightly less mC than neurons at all sites. Because neuron-rich hippocampal subregions and primary neurons cultures had less methylation than nonneural tissues, we hypothesize that neuroectodermal derivatives tend to be less methylated, whether or not GFAP is expressed. Four domains of methylated CpG sites are proposed on the basis of tissue and cell-type distribution: I) a constitutively methylated domain in the mid-upstream promoter; II) a testis-specific gradient of methylation in exon 1; III) a hypomethylated domain found in neuroectodermal derivatives; and IV) subsets of sites in the promoter and in exon 1 that have the least methylation in astrocytes, and therefore may be astrocyte-specific domains.
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Affiliation(s)
- B Teter
- Neurogerontology Division, Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191
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