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Central Stimulatory Effect of Kynurenic Acid on BDNF-TrkB Signaling and BER Enzymatic Activity in the Hippocampal CA1 Field in Sheep. Int J Mol Sci 2022; 24:ijms24010136. [PMID: 36613581 PMCID: PMC9820639 DOI: 10.3390/ijms24010136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/12/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Deficiency of neurotrophic factors and oxidative DNA damage are common causes of many neurodegenerative diseases. Recently, the importance of kynurenic acid (KYNA), an active metabolite of tryptophan, has increased as a neuroprotective molecule in the brain. Therefore, the present study tested the hypothesis that centrally acting KYNA would positively affect: (1) brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling and (2) selected base excision repair (BER) pathway enzymes activities in the hippocampal CA1 field in sheep. Both lower (20 μg in total) and higher (100 μg in total) doses of KYNA infused into the third brain ventricle differentially increased the abundance of BDNF and TrkB mRNA in the CA1 field; additionally, the higher dose increased BDNF tissue concentration. The lower dose of KYNA increased mRNA expression for 8-oxoguanine glycosylase (OGG1), N-methylpurine DNA glycosylase (MPG), and thymine DNA glycosylase and stimulated the repair of 1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxy-cytosine as determined by the excision efficiency of lesioned nucleobases. The higher dose increased the abundance of OGG1 and MPG transcripts, however, its stimulatory effect on repair activity was less pronounced in all cases compared to the lower dose. The increased level of AP-endonuclease mRNA expression was dose-dependent. In conclusion, the potential neurotrophic and neuroprotective effects of KYNA in brain cells may involve stimulation of the BDNF-TrkB and BER pathways.
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Exploring the Origin and Physiological Significance of DNA Double Strand Breaks in the Developing Neuroretina. Int J Mol Sci 2022; 23:ijms23126449. [PMID: 35742893 PMCID: PMC9224223 DOI: 10.3390/ijms23126449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 02/04/2023] Open
Abstract
Genetic mosaicism is an intriguing physiological feature of the mammalian brain that generates altered genetic information and provides cellular, and prospectively functional, diversity in a manner similar to that of the immune system. However, both its origin and its physiological significance remain poorly characterized. Most, if not all, cases of somatic mosaicism require prior generation and repair of DNA double strand breaks (DSBs). The relationship between DSB generation, neurogenesis, and early neuronal cell death revealed by our studies in the developing retina provides new perspectives on the different mechanisms that contribute to DNA rearrangements in the developing brain. Here, we speculate on the physiological significance of these findings.
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Induction of recurrent break cluster genes in neural progenitor cells differentiated from embryonic stem cells in culture. Proc Natl Acad Sci U S A 2020; 117:10541-10546. [PMID: 32332169 DOI: 10.1073/pnas.1922299117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mild replication stress enhances appearance of dozens of robust recurrent genomic break clusters, termed RDCs, in cultured primary mouse neural stem and progenitor cells (NSPCs). Robust RDCs occur within genes ("RDC-genes") that are long and have roles in neural cell communications and/or have been implicated in neuropsychiatric diseases or cancer. We sought to develop an in vitro approach to determine whether specific RDC formation is associated with neural development. For this purpose, we adapted a system to induce neural progenitor cell (NPC) development from mouse embryonic stem cell (ESC) lines deficient for XRCC4 plus p53, a genotype that enhances DNA double-strand break (DSB) persistence to enhance detection. We tested for RDCs by our genome-wide DSB identification approach that captures DSBs via their ability to join to specific genomic Cas9/single-guide RNA-generated bait DSBs. In XRCC4/p53-deficient ESCs, we detected seven RDCs, all of which were in genes and two of which were robust. In contrast, in NPCs derived from these ESC lines we detected 29 RDCs, a large fraction of which were robust and associated with long, transcribed neural genes that were also robust RDC-genes in primary NSPCs. These studies suggest that many RDCs present in NSPCs are developmentally influenced to occur in this cell type and indicate that induced development of NPCs from ESCs provides an approach to rapidly elucidate mechanistic aspects of NPC RDC formation.
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Khan C, Muliyil S, Rao BJ. Genome Damage Sensing Leads to Tissue Homeostasis in Drosophila. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2019; 345:173-224. [PMID: 30904193 DOI: 10.1016/bs.ircmb.2018.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA repair is a critical cellular process required for the maintenance of genomic integrity. It is now well appreciated that cells employ several DNA repair pathways to take care of distinct types of DNA damage. It is also well known that a cascade of signals namely DNA damage response or DDR is activated in response to DNA damage which comprise cellular responses, such as cell cycle arrest, DNA repair and cell death, if the damage is irreparable. There is also emerging literature suggesting a cross-talk between DNA damage signaling and several signaling networks within a cell. Moreover, cell death players themselves are also well known to engage in processes outside their canonical function of apoptosis. This chapter attempts to build a link between DNA damage, DDR and signaling from the studies mainly conducted in mammals and Drosophila model systems, with a special emphasis on their relevance in overall tissue homeostasis and development.
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Affiliation(s)
- Chaitali Khan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Sonia Muliyil
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - B J Rao
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India.
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5
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Three classes of recurrent DNA break clusters in brain progenitors identified by 3D proximity-based break joining assay. Proc Natl Acad Sci U S A 2018; 115:1919-1924. [PMID: 29432181 DOI: 10.1073/pnas.1719907115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We recently discovered 27 recurrent DNA double-strand break (DSB) clusters (RDCs) in mouse neural stem/progenitor cells (NSPCs). Most RDCs occurred across long, late-replicating RDC genes and were found only after mild inhibition of DNA replication. RDC genes share intriguing characteristics, including encoding surface proteins that organize brain architecture and neuronal junctions, and are genetically implicated in neuropsychiatric disorders and/or cancers. RDC identification relies on high-throughput genome-wide translocation sequencing (HTGTS), which maps recurrent DSBs based on their translocation to "bait" DSBs in specific chromosomal locations. Cellular heterogeneity in 3D genome organization allowed unequivocal identification of RDCs on 14 different chromosomes using HTGTS baits on three mouse chromosomes. Additional candidate RDCs were also implicated, however, suggesting that some RDCs were missed. To more completely identify RDCs, we exploited our finding that joining of two DSBs occurs more frequently if they lie on the same cis chromosome. Thus, we used CRISPR/Cas9 to introduce specific DSBs into each mouse chromosome in NSPCs that were used as bait for HTGTS libraries. This analysis confirmed all 27 previously identified RDCs and identified many new ones. NSPC RDCs fall into three groups based on length, organization, transcription level, and replication timing of genes within them. While mostly less robust, the largest group of newly defined RDCs share many intriguing characteristics with the original 27. Our findings also revealed RDCs in NSPCs in the absence of induced replication stress, and support the idea that the latter treatment augments an already active endogenous process.
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6
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Huppertz B, Kingdom JCP. Apoptosis in the Trophoblast—Role of Apoptosis in Placental Morphogenesis. ACTA ACUST UNITED AC 2016; 11:353-62. [PMID: 15350247 DOI: 10.1016/j.jsgi.2004.06.002] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Villous trophoblast is the epithelial cover of the placental villous tree and comes in direct contact with maternal blood. The turnover of villous trophoblast includes proliferation and differentiation of cytotrophoblast, syncytial fusion of cytotrophoblast with the overlying syncytiotrophoblast, differentiation in the syncytiotrophoblast, and finally extrusion of apoptotic material into the maternal circulation. In recent years, it has become clear that apoptosis is a normal constituent of trophoblast turnover and the release of apoptotic material does not lead to an inflammatory response of the mother. During preeclampsia there seems to be an altered balance between proliferation and apoptosis of villous trophoblast leading to a dysregulation of the release from the syncytiotrophoblast. The normal apoptotic release may be reduced in favor of a necrotic release. Since apoptosis is still ongoing in the syncytiotrophoblast, a necrotic release of intrasyncytial and partly apoptotic material lead us to call this type of release "aponecrotic shedding." In this situation, cell-free components such as G-actin and DNA freely floating in maternal blood may trigger damage to the maternal endothelium, thereby triggering preeclampsia. This review highlights the importance of the apoptosis cascade in permitting normal physiologic turnover of villous trophoblast. It will demonstrate the participation of initial stages of this cascade within the cytotrophoblast and of the execution stages within the syncytiotrophoblast. Moreover, this review presents hypotheses of how dysregulation of the apoptosis cascade may be linked to endothelial dysfunction of the maternal vasculature in preeclampsia.
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Affiliation(s)
- Berthold Huppertz
- Department of Anatomy II, University Hospital RWTH, Aachen, Germany.
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7
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Abstract
Elucidating the mechanisms that regulate the life versus death of mammalian neurons is important not only for our understanding of the normal biology of the nervous system but also for our efforts to devise approaches to maintain neuronal survival in the face of traumatic injury or neurodegenerative disorders. Here, we review the emerging evidence that a key survival/death checkpoint in both peripheral and central neurons involves the p53 tumor suppressor and its newly discovered family members, p73 and p63. The full-length isoforms of these proteins function as proapoptotic proteins, whereas naturally occurring N-terminal truncated variants of p73 and p63 act as prosurvival proteins, at least partially by antagonizing the full-length family members. The authors propose that together, these isoforms comprise an upstream rheostat that sums different environmental cues to ultimately determine neuronal survival during development, during neuronal maintenance in adult animals, and even following traumatic injury.
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Affiliation(s)
- W Bradley Jacobs
- Developmental Biology and Cancer Research, Hospital for Sick Children, Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
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8
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Chung KM, Park H, Jung S, Ha S, Yoo SJ, Woo H, Lee HJ, Kim SW, Kim EK, Moon C, Yu SW. Calpain Determines the Propensity of Adult Hippocampal Neural Stem Cells to Autophagic Cell Death Following Insulin Withdrawal. Stem Cells 2015; 33:3052-64. [DOI: 10.1002/stem.2082] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/12/2015] [Accepted: 05/23/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Kyung Min Chung
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Hyunhee Park
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Seonghee Jung
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Shinwon Ha
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Seung-Jun Yoo
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Hanwoong Woo
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Hyang Ju Lee
- Department of Biochemistry and Molecular Biology; Asan Medical Center, University of Ulsan College of Medicine; Seoul Republic of Korea
| | - Seong Who Kim
- Department of Biochemistry and Molecular Biology; Asan Medical Center, University of Ulsan College of Medicine; Seoul Republic of Korea
| | - Eun-Kyoung Kim
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
- Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Cheil Moon
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
- Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
| | - Seong-Woon Yu
- Department of Brain and Cognitive Sciences; Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
- Neurometabolomics Research Center, Daegu Gyeongbuk Institute of Science and Technology (DGIST); Daegu Republic of Korea
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Liu WW, Chen SY, Cheng CH, Cheng HJ, Huang PH. Blm-s , a BH3-Only Protein Enriched in Postmitotic Immature Neurons, Is Transcriptionally Upregulated by p53 during DNA Damage. Cell Rep 2014; 9:166-179. [DOI: 10.1016/j.celrep.2014.08.050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/05/2014] [Accepted: 08/20/2014] [Indexed: 12/25/2022] Open
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10
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Yang JL, Lin YT, Chuang PC, Bohr VA, Mattson MP. BDNF and exercise enhance neuronal DNA repair by stimulating CREB-mediated production of apurinic/apyrimidinic endonuclease 1. Neuromolecular Med 2014; 16:161-174. [PMID: 24114393 PMCID: PMC3948322 DOI: 10.1007/s12017-013-8270-x] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 09/26/2013] [Indexed: 01/11/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) promotes the survival and growth of neurons during brain development and mediates activity-dependent synaptic plasticity and associated learning and memory in the adult. BDNF levels are reduced in brain regions affected in Alzheimer's, Parkinson's, and Huntington's diseases, and elevation of BDNF levels can ameliorate neuronal dysfunction and degeneration in experimental models of these diseases. Because neurons accumulate oxidative lesions in their DNA during normal activity and in neurodegenerative disorders, we determined whether and how BDNF affects the ability of neurons to cope with oxidative DNA damage. We found that BDNF protects cerebral cortical neurons against oxidative DNA damage-induced death by a mechanism involving enhanced DNA repair. BDNF stimulates DNA repair by activating cyclic AMP response element-binding protein (CREB), which, in turn, induces the expression of apurinic/apyrimidinic endonuclease 1 (APE1), a key enzyme in the base excision DNA repair pathway. Suppression of either APE1 or TrkB by RNA interference abolishes the ability of BDNF to protect neurons against oxidized DNA damage-induced death. The ability of BDNF to activate CREB and upregulate APE1 expression is abolished by shRNA of TrkB as well as inhibitors of TrkB, PI3 kinase, and Akt kinase. Voluntary running wheel exercise significantly increases levels of BDNF, activates CREB, and upregulates APE1 in the cerebral cortex and hippocampus of mice, suggesting a novel mechanism whereby exercise may protect neurons from oxidative DNA damage. Our findings reveal a previously unknown ability of BDNF to enhance DNA repair by inducing the expression of the DNA repair enzyme APE1.
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Affiliation(s)
- Jenq-Lin Yang
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD 21224, USA; Laboratory of Molecular Gerontology, National Institute on Aging Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD 21224, USA; Center for Translation Research in Biomedical Sciences, Kaohsiung Chang Gung Memorial Hospital, 123 Ta Pei Road, Kaohsiung 83301, Taiwan
| | - Yu-Ting Lin
- Center for Translation Research in Biomedical Sciences, Kaohsiung Chang Gung Memorial Hospital, 123 Ta Pei Road, Kaohsiung 83301, Taiwan
| | - Pei-Chin Chuang
- Department of Medical Research, Kaohsiung Chang Gung, Memorial Hospital, 123 Ta Pei Road, Kaohsiung 83301, Taiwan
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD 21224, USA
| | - Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Boulevard, Baltimore, MD 21224, USA
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11
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Herrup K. ATM and the epigenetics of the neuronal genome. Mech Ageing Dev 2013; 134:434-9. [PMID: 23707635 DOI: 10.1016/j.mad.2013.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 05/01/2013] [Accepted: 05/17/2013] [Indexed: 01/28/2023]
Abstract
Ataxia-telangiectasia (A-T) is a neurodegenerative syndrome caused by the mutation of the ATM gene. The ATM protein is a PI3kinase family member best known for its role in the DNA damage response. While repair of DNA damage is a critical function that every CNS neuron must perform, a growing body of evidence indicates that the full range of ATM functions includes some that are unrelated to DNA damage yet are essential to neuronal survival and normal function. For example, ATM participates in the regulation of synaptic vesicle trafficking and is essential for the maintenance of normal LTP. In addition ATM helps to ensure the cytoplasmic localization of HDAC4 and thus maintains the histone 'code' of the neuronal genome by suppressing genome-wide histone deacetylation, which alters the message and protein levels of many genes that are important for neuronal survival and function. The growing list of ATM functions that go beyond its role in the DNA damage response offers a new perspective on why individuals with A-T express such a wide range of neurological symptoms, and suggests that not all A-T symptoms need to be understood in the context of the DNA repair process.
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Affiliation(s)
- Karl Herrup
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, United States; Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
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12
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Zeinab RA, Wu H, Sergi C, Leng R. UBE4B: a promising regulatory molecule in neuronal death and survival. Int J Mol Sci 2012; 13:16865-79. [PMID: 23222733 PMCID: PMC3546727 DOI: 10.3390/ijms131216865] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 11/22/2012] [Accepted: 11/27/2012] [Indexed: 12/13/2022] Open
Abstract
Neuronal survival and death of neurons are considered a fundamental mechanism in the regulation of the nervous system during early development of the system and in adulthood. Defects in this mechanism are highly problematic and are associated with many neurodegenerative diseases. Because neuronal programmed death is apoptotic in nature, indicating that apoptosis is a key regulatory process, the p53 family members (p53, p73, p63) act as checkpoints in neurons due to their role in apoptosis. The complexity of this system is due to the existence of different naturally occurring isoforms that have different functions from the wild types (WT), varying from apoptotic to anti-apoptotic effects. In this review, we focus on the role of UBE4B (known as Ube4b or Ufd2a in mouse), an E3/E4 ligase that triggers substrate polyubiquitination, as a master regulatory ligase associated with the p53 family WT proteins and isoforms in regulating neuronal survival. UBE4B is also associated with other pathways independent of the p53 family, such as polyglutamine aggregation and Wallerian degeneration, both of which are critical in neurodegenerative diseases. Many of the hypotheses presented here are gateways to understanding the programmed death/survival of neurons regulated by UBE4B in normal physiology, and a means of introducing potential therapeutic approaches with implications in treating several neurodegenerative diseases.
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Affiliation(s)
- Rami Abou Zeinab
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2S2, Canada.
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13
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Essential oil and 1,8-cineole from Artemisia lavandulaefolia induces apoptosis in KB cells via mitochondrial stress and caspase activation. Food Sci Biotechnol 2010. [DOI: 10.1007/s10068-010-0025-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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14
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Gericke GS. Common chromosomal fragile sites (CFS) may be involved in normal and traumatic cognitive stress memory consolidation and altered nervous system immunity. Med Hypotheses 2010; 74:911-8. [PMID: 20138440 DOI: 10.1016/j.mehy.2009.05.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 05/22/2009] [Accepted: 05/26/2009] [Indexed: 11/18/2022]
Abstract
Previous reports of specific patterns of increased fragility at common chromosomal fragile sites (CFS) found in association with certain neurobehavioural disorders did not attract attention at the time due to a shift towards molecular approaches to delineate neuropsychiatric disorder candidate genes. Links with miRNA, altered methylation and the origin of copy number variation indicate that CFS region characteristics may be part of chromatinomic mechanisms that are increasingly linked with neuroplasticity and memory. Current reports of large-scale double-stranded DNA breaks in differentiating neurons and evidence of ongoing DNA demethylation of specific gene promoters in adult hippocampus may shed new light on the dynamic epigenetic changes that are increasingly appreciated as contributing to long-term memory consolidation. The expression of immune recombination activating genes in key stress-induced memory regions suggests the adoption by the brain of this ancient pattern recognition and memory system to establish a structural basis for long-term memory through controlled chromosomal breakage at highly specific genomic regions. It is furthermore considered that these mechanisms for management of epigenetic information related to stress memory could be linked, in some instances, with the transfer of the somatically acquired information to the germline. Here, rearranged sequences can be subjected to further selection and possible eventual retrotranscription to become part of the more stable coding machinery if proven to be crucial for survival and reproduction. While linkage of cognitive memory with stress and fear circuitry and memory establishment through structural DNA modification is proposed as a normal process, inappropriate activation of immune-like genomic rearrangement processes through traumatic stress memory may have the potential to lead to undesirable activation of neuro-inflammatory processes. These theories could have a significant impact on the interpretation of risks posed by heredity and the environment and the search for neuropsychiatric candidate genes.
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Affiliation(s)
- G S Gericke
- Department of Biomedical Sciences, Tshwane University of Technology, Brooklyn Square, Pretoria, Gauteng, South Africa.
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15
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McConnell MJ, MacMillan HR, Chun J. Mathematical modeling supports substantial mouse neural progenitor cell death. Neural Dev 2009; 4:28. [PMID: 19602274 PMCID: PMC2729736 DOI: 10.1186/1749-8104-4-28] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 07/14/2009] [Indexed: 01/24/2023] Open
Abstract
Background Existing quantitative models of mouse cerebral cortical development are not fully constrained by experimental data. Results Here, we use simple difference equations to model neural progenitor cell fate decisions, incorporating intermediate progenitor cells and initially low rates of neural progenitor cell death. Also, we conduct a sensitivity analysis to investigate possible uncertainty in the fraction of cells that divide, differentiate, and die at each cell cycle. Conclusion We demonstrate that uniformly low-level neural progenitor cell death, as concluded in previous models, is incompatible with normal mouse cortical development. Levels of neural progenitor cell death up to and exceeding 50% are compatible with normal cortical development and may operate to prevent forebrain overgrowth as observed following cell death attenuation, as occurs in caspase 3-null mutant mice.
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Affiliation(s)
- Michael J McConnell
- Crick-Jacobs Center for Theoretical and Computational Biology, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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16
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An integrative view of dynamic genomic elements influencing human brain evolution and individual neurodevelopment. Med Hypotheses 2008; 71:360-73. [DOI: 10.1016/j.mehy.2008.03.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2008] [Revised: 03/01/2008] [Accepted: 03/06/2008] [Indexed: 11/23/2022]
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17
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Barzilai A, Biton S, Shiloh Y. The role of the DNA damage response in neuronal development, organization and maintenance. DNA Repair (Amst) 2008; 7:1010-27. [DOI: 10.1016/j.dnarep.2008.03.005] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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18
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Yamauchi H, Katayama KI, Ueno M, He XJ, Mikami T, Uetsuka K, Doi K, Nakayama H. Essential role of p53 in trophoblastic apoptosis induced in the developing rodent placenta by treatment with a DNA-damaging agent. Apoptosis 2008; 12:1743-54. [PMID: 17594519 DOI: 10.1007/s10495-007-0099-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Placental apoptosis plays important roles in both normal morphogenesis and pathogenesis. We previously reported that administration of cytosine arabinoside (Ara-C), a DNA-damaging agent, to pregnant rats induced apoptosis of trophoblasts in the placental labyrinth zone. Our aim here was to clarify the molecular pathway of DNA damage induced-trophoblastic apoptosis. We found the accumulation and phosphorylation of p53 protein, a tumor suppressor that mediates apoptosis under various cellular stresses, in Ara-C-treated rat placentas. Expression of the mRNAs of downstream targets of p53 was upregulated, suggesting that p53 exerts its function as a transcription factor. We also observed release of mitochondrial cytochrome c and activation of caspase-9, hallmarks of the intrinsic apoptotic pathway. Phosphorylation of Chk1 and H2A.X, target substrates of DNA damage transducers, was detected immediately after Ara-C treatment, suggesting activation of DNA damage cascades to phosphorylate p53. Ara-C-induced trophoblastic apoptosis was almost completely abrogated in placentas of Trp53 (coding p53)-deficient mice, whereas the levels of physiological apoptosis in trophoblasts were similar among wild-type and Trp53-deficient mice. These results indicate that p53 is essential for DNA damage-induced trophoblastic apoptosis and suggest that the mechanisms that regulate the damage-induced apoptosis differ from those that regulate physiological apoptosis.
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Affiliation(s)
- Hirofumi Yamauchi
- Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
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19
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Heat shock protein 70 expression in epilepsy suggests stress rather than protection. Acta Neuropathol 2008; 115:219-30. [PMID: 17929041 DOI: 10.1007/s00401-007-0297-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 08/29/2007] [Accepted: 09/13/2007] [Indexed: 01/23/2023]
Abstract
Although heat shock protein 70 (HSP70) has been suggested to be a stress marker or to play a protective role in brain injury, the relevance of its pathological expression in epilepsy is unclear. We investigated the expression of HSP70 in brain tissue from human temporal lobe epilepsy (TLE) patients and from kainic acid (KA)-induced seizure-related neuronal damage in vivo and in vitro. The human TLE tissue showed severe neuronal loss and gliosis in hippocampal CA3 area. The KA-induced neuronal damage was similar to pathological changes of the TLE hippocampus. An increased number of TUNEL-positive cells were observed at day 5 when compared with day 2 after seizure induction. Intense HSP70 immunofluorescence was observed in hippocampal CA3 pyramidal neurons of rat, 2 days following KA administration, which then declined in labeling by day 5. No HSP70 expression was found in Fluoro-Jade B positive dying neurons by double staining. Western blot analysis showed an increased level of p53 and Bax expression following KA treatment. In vitro, there was no apparent difference in the degree of apoptosis between HSP70 siRNA- and control empty vector-transfected primary neurons following KA treatment. Our results revealed that HSP70 was a useful indicator of stressed neurons in acute phase of epilepsy, but not associated with neuronal death, thereby suggesting that HSP70 played no role in neuroprotection during an epileptogenic state.
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Abstract
More than half of the initially-formed neurons are deleted in certain brain regions during normal development. This process, whereby cells are discretely removed without interfering with the further development of remaining cells, is called programmed cell death (PCD). The term apoptosis is used to describe certain morphological manifestations of PCD. Many of the effectors of this developmental cell death program are highly expressed in the developing brain, making it more susceptible to accidental activation of the death machinery, e.g. following hypoxia-ischemia or irradiation. Recent evidence suggests, however, that activation and regulation of cell death mechanisms under pathological conditions do not exactly mirror physiological, developmentally regulated PCD. It may be argued that the conditions after e.g. ischemia are not even compatible with the execution of PCD as we know it. Under pathological conditions cells are exposed to various stressors, including energy failure, oxidative stress and unbalanced ion fluxes. This results in parallel triggering and potential overshooting of several different cell death pathways, which then interact with one another and result in complex patterns of biochemical manifestations and cellular morphological features. These types of cell death are here called "pathological apoptosis," where classical hallmarks of PCD, like pyknosis, nuclear condensation and caspase-3 activation, are combined with non-PCD features of cell death. Here we review our current knowledge of the mechanisms involved, with special focus on the potential for therapeutic intervention tailored to the needs of the developing brain.
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Affiliation(s)
- Klas Blomgren
- Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Göteborg University, SE 405 30 Göteborg, Sweden.
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Mehler MF, Mattick JS. Noncoding RNAs and RNA Editing in Brain Development, Functional Diversification, and Neurological Disease. Physiol Rev 2007; 87:799-823. [PMID: 17615389 DOI: 10.1152/physrev.00036.2006] [Citation(s) in RCA: 224] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The progressive maturation and functional plasticity of the nervous system in health and disease involve a dynamic interplay between the transcriptome and the environment. There is a growing awareness that the previously unexplored molecular and functional interface mediating these complex gene-environmental interactions, particularly in brain, may encompass a sophisticated RNA regulatory network involving the twin processes of RNA editing and multifaceted actions of numerous subclasses of non-protein-coding RNAs. The mature nervous system encompasses a wide range of cell types and interconnections. Long-term changes in the strength of synaptic connections are thought to underlie memory retrieval, formation, stabilization, and effector functions. The evolving nervous system involves numerous developmental transitions, such as neurulation, neural tube patterning, neural stem cell expansion and maintenance, lineage elaboration, differentiation, axonal path finding, and synaptogenesis. Although the molecular bases for these processes are largely unknown, RNA-based epigenetic mechanisms appear to be essential for orchestrating these precise and versatile biological phenomena and in defining the etiology of a spectrum of neurological diseases. The concerted modulation of RNA editing and the selective expression of non-protein-coding RNAs during seminal as well as continuous state transitions may comprise the plastic molecular code needed to couple the intrinsic malleability of neural network connections to evolving environmental influences to establish diverse forms of short- and long-term memory, context-specific behavioral responses, and sophisticated cognitive capacities.
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Affiliation(s)
- Mark F Mehler
- Institute for Brain Disorders and Neural Regeneration, Department of Neurology, Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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22
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Herrup K, Yang Y. Cell cycle regulation in the postmitotic neuron: oxymoron or new biology? Nat Rev Neurosci 2007; 8:368-78. [PMID: 17453017 DOI: 10.1038/nrn2124] [Citation(s) in RCA: 365] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adult CNS neurons are typically described as permanently postmitotic but there is probably nothing permanent about the neuronal cell cycle arrest. Rather, it appears that these highly differentiated cells must constantly keep their cell cycle in check. Relaxation of this vigilance leads to the initiation of a cell cycle and entrance into an altered and vulnerable state, often leading to death. There is evidence that neurons which are at risk of neurodegeneration are also at risk of re-initiating a cell cycle process that involves the expression of cell cycle proteins and DNA replication. Failure of cell cycle regulation might be a root cause of several neurodegenerative disorders and a final common pathway for others.
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Affiliation(s)
- Karl Herrup
- Department of Cell Biology and Neuroscience, Rutgers University, 604 Allison Road, Piscataway, New Jersey 08854, USA.
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23
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Sjakste NI, Sjakste TG. Possible involvement of DNA breaks in epigenetic regulation of cell differentiation. RUSS J GENET+ 2007. [DOI: 10.1134/s1022795407050018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Gohlke JM, Griffith WC, Faustman EM. Computational models of neocortical neuronogenesis and programmed cell death in the developing mouse, monkey, and human. ACTA ACUST UNITED AC 2007; 17:2433-42. [PMID: 17204816 DOI: 10.1093/cercor/bhl151] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This paper presents a computational model allowing quantitative simulations of acquisition of neocortical neuronal number across mammalian species. When extrapolating scientific findings from rodents to humans, it is particularly pertinent to acknowledge the importance of the accelerated enlargement of the neocortex during human evolution. Neocortex development is marked by discrete stages of neural progenitor cell proliferation and death, neuronal differentiation, and neuronal programmed cell death. We have developed computational models of human and rhesus monkey neocortical neuronal cell acquisition based on experimentally derived parameters of cell cycle length, commitment to cell cycle exit, and cell death. Our model results agree with independent stereological studies estimating neocortical neuron number in adult and developing rhesus monkey and human. Comparisons of our primate models with previously developed rodent models suggest correlations between the lengthening of the duration of the neuronogenesis period and a lengthening of the cellular processes of cell cycle progression and death can account for the vast increase in size of the primate neocortex. Furthermore, when compared with rodents, we predict that cell death may play a larger role in shaping the primate neocortex. Our mathematical models of the development and evolution of the neocortex provide a quantitative, biologically based construct for extrapolation between rodent and humans. These models can assist in focusing future experimental research on the differing mechanisms of rodent versus human neocortical development.
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Affiliation(s)
- Julia M Gohlke
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Seattle, WA 98105, USA
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25
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Zhang P, Dilley C, Mattson MP. DNA damage responses in neural cells: Focus on the telomere. Neuroscience 2007; 145:1439-48. [PMID: 17207936 PMCID: PMC1924472 DOI: 10.1016/j.neuroscience.2006.11.052] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 11/20/2006] [Accepted: 11/22/2006] [Indexed: 01/24/2023]
Abstract
Postmitotic neurons must survive for the entire life of the organism and be able to respond adaptively to adverse conditions of oxidative and genotoxic stress. Unrepaired DNA damage can trigger apoptosis of neurons which is typically mediated by the ataxia telangiectasia mutated (ATM)-p53 pathway. As in all mammalian cells, telomeres in neurons consist of TTAGGG DNA repeats and several associated proteins that form a nucleoprotein complex that prevents chromosome ends from being recognized as double strand breaks. Proteins that stabilize telomeres include TRF1 and TRF2, and proteins known to play important roles in DNA damage responses and DNA repair including ATM, Werner and the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). We have been performing studies of developing and adult neurons aimed at understanding the effects of global and telomere-directed DNA damage responses in neuronal plasticity and survival in the contexts of aging and neurodegenerative disorders. Deficits in specific DNA repair proteins, including DNA-PKcs and uracil DNA glycosylase (UDG), render neurons vulnerable to adverse conditions of relevance to the pathogenesis of neurodegenerative disorders such as Alzheimer's disease and stroke. Similarly, early postmitotic neurons with reduced telomerase activity exhibit accentuated responses to DNA damage and are prone to apoptosis demonstrating a pivotal role for telomere maintenance in both mitotic cells and postmitotic neurons. Our recent findings suggest key roles for TRF2 in regulating the differentiation and survival of neurons. TRF2 affects cell survival and differentiation by modulating DNA damage pathways, and gene expression. A better understanding of the molecular mechanisms by which neurons respond to global and telomere-specific DNA damage may reveal novel strategies for prevention and treatment of neurodegenerative disorders. Indeed, work in this and other laboratories has shown that dietary folic acid can protect neurons against Alzheimer's disease by keeping homocysteine levels low and thereby minimizing the misincorporation of uracil into DNA in neurons.
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Affiliation(s)
- P Zhang
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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26
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Besirli CG, Johnson EM. The activation loop phosphorylation of protein kinase D is an early marker of neuronal DNA damage. J Neurochem 2006; 99:218-25. [PMID: 16911582 DOI: 10.1111/j.1471-4159.2006.04116.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In neurons, DNA damage induces protein synthesis-dependent apoptosis mediated by the mitochondrial intrinsic cell-death pathway. Signal transduction cascades activated by genotoxic stress upstream of the mitochondria are largely unknown. We identified protein kinase D (PKD) as one of the earliest markers of neuronal DNA damage. Phosphorylation of the PKD-activation domain could be detected within 15 min of genotoxic stress and was concurrent with ataxia telangiectasia-mutated (ATM) activation. PKD stimulation was selective to DNA damage and did not occur with other stress stimuli examined. In vivo, both young and adult rats showed increased levels of phosphorylated PKD in neuronal tissues after injection of DNA-toxin etoposide. These results indicate that PKD activation is an early neuronal response to DNA damage, suggesting that signaling downstream of PKD may be critical for neuronal survival after genotoxic stress.
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Affiliation(s)
- Cagri G Besirli
- Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri, USA
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27
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Mattson MP, Meffert MK. Roles for NF-kappaB in nerve cell survival, plasticity, and disease. Cell Death Differ 2006; 13:852-60. [PMID: 16397579 DOI: 10.1038/sj.cdd.4401837] [Citation(s) in RCA: 441] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Here we review evidence of roles for NF-kappaB in the regulation of developmental and synaptic plasticity, and cell survival in physiological and pathological settings. Signaling pathways modulating NF-kappaB activity include those engaged by neurotrophic factors, neurotransmitters, electrical activity, cytokines, and oxidative stress. Emerging findings support a pivotal role for NF-kappaB as a mediator of transcription-dependent enduring changes in the structure and function of neuronal circuits. Distinct subunits of NF-kappaB may uniquely affect cognition and behavior by regulating specific target genes. NF-kappaB activation can prevent the death of neurons by inducing the production of antiapoptotic proteins such as Bcl-2, IAPs and manganese superoxide dismutase (Mn-SOD). Recent findings indicate that NF-kappaB plays important roles in disorders such as epilepsy, stroke, Alzheimer's and Parkinson's diseases, as well as oncogenesis. Molecular pathways upstream and downstream of NF-kappaB in neurons are being elucidated and may provide novel targets for therapeutic intervention in various neurological disorders.
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Affiliation(s)
- M P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, USA.
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28
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29
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30
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Young KM, Bartlett PF, Coulson EJ. Neural progenitor number is regulated by nuclear factor-kappaB p65 and p50 subunit-dependent proliferation rather than cell survival. J Neurosci Res 2006; 83:39-49. [PMID: 16307445 DOI: 10.1002/jnr.20702] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The number of cells generated by a proliferating stem or precursor cell can be influenced both by proliferation and by the degree of cell death/survival of the progeny generated. In this study, the extent to which cell survival controls progenitor number was examined by comparing the growth characteristics of neurosphere cultures derived from mice lacking genes for the death-inducing Bcl-2 homologue Hara Kiri (Hrk), apoptosis-associated protein 1 (Apaf1), or the prosurvival nuclear factor-kappaB (NFkappaB) subunits p65, p50, or c-rel. We found no evidence that Hrk or Apaf1, and by inference the mitochondrial cell death pathway, are involved in regulating the number of neurosphere-derived progeny. However, we identified the p65p50 NFkappaB dimer as being required for the normal growth and expansion of neurosphere cultures. Genetic loss of both p65 and p50 NFkappaB subunits resulted in a reduced number of progeny but an increased proportion of neurons. No effect on cell survival was observed. This suggests that the number and fate of neural progenitor cells are more strongly regulated by cell cycle control than survival.
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Affiliation(s)
- Kaylene M Young
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
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31
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Abstract
Programmed cell death is a relevant process in the physiology and pathology of the nervous system. Neuronal cell death during development is well characterized, and studies of this process have provided valuable information regarding the regulatory mechanisms of cell death in the nervous system. In the last few years, cell death occurring at earlier developmental stages and affecting proliferating neuroepithelial cells and recently born neuroblasts has been recognized. In this review we cover the observations on cell death in the early, proliferating stages of vertebrate neural development. Genetically modified mouse model systems and complementary in vivo approaches in other vertebrates have provided a solid basis for its relevance and contribution to normal neural development, as well as for the pathological consequences of its deregulation. However, the precise functional role of cell death remains a topic of debate.
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Affiliation(s)
- Patricia Boya
- Group of Growth Factors in Vertebrate Development, Department of Cell and Developmental Biology, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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32
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Vyjayanti VN, Rao KS. DNA double strand break repair in brain: reduced NHEJ activity in aging rat neurons. Neurosci Lett 2005; 393:18-22. [PMID: 16226837 DOI: 10.1016/j.neulet.2005.09.053] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Revised: 09/10/2005] [Accepted: 09/13/2005] [Indexed: 11/23/2022]
Abstract
Linearised pUC 19 DNA with cohesive, blunt and non-matching ends, generated by prior treatment with different restriction enzymes was presented as substrate to measure the NHEJ activity to repair DNA double strand breaks in extracts prepared from isolated neurons from neonatal, young adult and old rat cerebral cortex. Highest end joining activity was noticed with the substrates having cohesive 3' overhang (PstI) or 5' overhang (EcoRI) ends and this activity is significantly reduced with age. However, blunt and non-matching ends were very poorly repaired at all ages. Further, the end joining activity in neurons is not faithful and sequence changes occur during the repair process. Also, the end joining activity in old neuronal extracts, but not in young extracts, was found to decline very rapidly with time of cold storage. These findings, the first of their kind, thus demonstrate that neuronal cells have the capacity to repair DNA double strand breaks through error prone NHEJ mode and that the cohesive end joining activity decreases with age of the animal.
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Affiliation(s)
- V N Vyjayanti
- ICMR Center for Research on Aging and Brain, CRAB, Department of Biochemistry, School of Life Sciences, University of Hyderabad, Gachibowli, Andhra Pradesh 500046, India
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33
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Buzańska L, Habich A, Jurga M, Sypecka J, Domańska-Janik K. Human cord blood-derived neural stem cell line—Possible implementation in studying neurotoxicity. Toxicol In Vitro 2005; 19:991-9. [PMID: 16084685 DOI: 10.1016/j.tiv.2005.06.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Accepted: 06/17/2005] [Indexed: 10/25/2022]
Abstract
Neural stem cell line developed from human umbilical cord blood (HUCB-NSC) [Buzańska et al., 2003. Journal of Neurochemistry 85, 33] is an ethically uncontroversial source of stem cells, able to differentiate into neuronal, astrocytic and oligodendroglial lineages. Developmental fate decisions of HUCB-NSC can be experimentally manipulated in vitro by the presence of trophic factors, mitogenes and neuromorphogenes, but can also be influenced by neurotoxins. In this report two-dimensional (2-D) and three-dimensional (3-D) HUCB-NSC cultures are introduced as useful models for testing developmental neurotoxicity. For 2-D culture models we established a standardized method for the assessment of the growth rate and cell differentiation in 96-well plates. The proliferative capacity of the HUCB-NSC was monitored by the MTT test while their ability to differentiate into neural-like cells by immunocytochemistry of beta-tubulin III and MAP-2 for neurons, GFAP and S-100beta for astrocytes and GalC for oligodendrocytes. The 3-D culture of HUCB-NSC is represented by neurospheres. Proliferation and migration of the intermediate precursors from attached neurospheres are shown to be controlled and altered by various growth factors and further modulated by the extracellular matrix component-fibronectin. Thus, neurospheres derived from the HUCB-NSC line can represent a suitable model of the activation of dormant stem cells residing in their niche, and can be used for neurotoxic studies.
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Affiliation(s)
- L Buzańska
- NeuroRepair Department, Medical Research Center, Polish Academy of Sciences, Pawińskiego 5 Str, 02-106 Warsaw, Poland
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34
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Niimi N, Sugo N, Aratani Y, Koyama H. Genetic interaction between DNA polymerase beta and DNA-PKcs in embryogenesis and neurogenesis. Cell Death Differ 2005; 12:184-91. [PMID: 15647757 DOI: 10.1038/sj.cdd.4401543] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
DNA polymerase beta (Polbeta) has been implicated in base excision repair. Polbeta knockout mice exhibit apoptosis in postmitotic neuronal cells and die at birth. Also, mice deficient in nonhomologous end-joining (NHEJ), a major pathway for DNA double-strand break repair, cause massive neuronal apoptosis. Severe combined immunodeficiency (SCID) mice have a mutation in the gene encoding DNA-dependent protein kinase catalytic subunit (DNA-PKcs), the component of NHEJ, and exhibit defective lymphogenesis. To study the interaction between Polbeta and DNA-PKcs, we generated mice doubly deficient in Polbeta and DNA-PKcs. Polbeta(-/-)DNA-PKcs(scid/scid) embryos displayed greater developmental delay, more extensive neuronal apoptosis, and earlier lethality than Polbeta(-/-) and DNA-PKcs(scid/scid) embryos. Furthermore, to study the involvement of p53 in the phenotype, we generated Polbeta(-/-)DNA-PKcs(scid/scid)p53(-/-) triple-mutant mice. The mutants did not exhibit apoptosis but were lethal with defective neurulation at midgestation. These results suggest a genetic interaction between Polbeta and DNA-PKcs in embryogenesis and neurogenesis.
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Affiliation(s)
- N Niimi
- Kihara Institute for Biological Research and Graduate School of Integrated Science, Yokohama City University, 641-12 Maioka-cho, Totsuka-ku, Yokohama 244-0813, Japan
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35
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Abstract
The transcription factor nuclear factor kappa-B (NF-kappaB) is involved in regulating responses of neurons to activation of several different signaling pathways in a variety of physiological and pathological settings. During development of the nervous system NF-kappaB is activated in growing neurons by neurotrophic factors and can induce the expression of genes involved in cell differentiation and survival. In the mature nervous system NF-kappaB is activated in synapses in response to excitatory synaptic transmission and may play a pivotal role in processes such as learning and memory. NF-kappaB is activated in neurons and glial cells in acute neurodegenerative conditions such as stroke and traumatic injury, as well as in chronic neurodegenerative conditions such as Alzheimer's disease. Activation of NF-kappaB in neurons can promote their survival by inducing the expression of genes encoding anti-apoptotic proteins such as Bcl-2 and the antioxidant enzyme Mn-superoxide dismutase. On the other hand, by inducing the production and release of inflammatory cytokines, reactive oxygen molecules and excitotoxins, activation of NF-kappaB in microglia and astrocytes may contribute to neuronal degeneration. Emerging findings suggest roles for NF-kappaB as a mediator of effects of behavioral and dietary factors on neuronal plasticity. NF-kappaB provides an attractive target for the development of novel therapeutic approaches for a range of neurological disorders.
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Affiliation(s)
- Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
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36
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Abstract
DNA double-strand breaks (DSBs) require a coordinated molecular response to ensure cellular or organism survival. Many factors required for the DSB response, including those involved in non-homologous end joining (NHEJ) and homologous recombination repair (HRR) are essential during nervous system development. Additionally, human syndromes resulting from defective responses to DNA damage often feature overt neuropathology such as neurodegeneration. Thus, appropriate responses to DSBs are critical for the normal development and maintenance of the nervous system.
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Affiliation(s)
- Clint W Abner
- Department of Genetics & Tumor Cell Biology, St. Jude Children's Research Hospital, 332N Lauderdale, Memphis, TN 38105, USA
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37
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Peng H, Huang Y, Duan Z, Erdmann N, Xu D, Herek S, Zheng J. Cellular IAP1 regulates TRAIL-induced apoptosis in human fetal cortical neural progenitor cells. J Neurosci Res 2005; 82:295-305. [PMID: 16180223 DOI: 10.1002/jnr.20629] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Neural stem/progenitor cells (NPCs) are present in the developing and adult central nervous system. NPC apoptosis is an important aspect of normal brain development. We show that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 2 is highly expressed on human NPCs derived from fetal cortex, yet TRAIL induces only minimal levels of apoptosis in NPCs. Caspase-8 mRNA and protein, an important factor in the TRAIL-mediated death pathway, is present at low levels in human NPCs. In contrast, inhibitors of apoptosis proteins (IAP), such as c-IAP1, are highly expressed. The transcription inhibitor actinomycin D sensitized human NPCs to TRAIL-induced apoptosis. Further, inhibition of cellular inhibitors of apoptosis protein 1 (c-IAP1) expression by small interfering RNA (siRNA) increased TRAIL-mediated caspase-3 activation and apoptosis; thus, c-IAP1 protects NPCs against TRAIL-induced apoptosis and suppresses caspase-3 activation. These findings illustrate the mechanisms for NPC resistance to apoptotic agonists such as TRAIL, and demonstrate a potentially important mechanism in CNS disease states.
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Affiliation(s)
- Hui Peng
- Laboratory of Neurotoxicology at the Center for Neurovirology and Neurodegenerative Disorders, University of Nebraska Medical Center, Omaha, Nebraska
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38
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Abstract
Affecting 1-3% of the population, mental retardation (MR) poses significant challenges for clinicians and scientists. Understanding the biology of MR is complicated by the extraordinary heterogeneity of genetic MR disorders. Detailed analyses of >1000 Online Mendelian Inheritance in Man (OMIM) database entries and literature searches through September 2003 revealed 282 molecularly identified MR genes. We estimate that hundreds more MR genes remain to be identified. A novel test, in which we distributed unmapped MR disorders proportionately across the autosomes, failed to eliminate the well-known X-chromosome overrepresentation of MR genes and candidate genes. This evidence argues against ascertainment bias as the main cause of the skewed distribution. On the basis of a synthesis of clinical and laboratory data, we developed a biological functions classification scheme for MR genes. Metabolic pathways, signaling pathways, and transcription are the most common functions, but numerous other aspects of neuronal and glial biology are controlled by MR genes as well. Using protein sequence and domain-organization comparisons, we found a striking conservation of MR genes and genetic pathways across the approximately 700 million years that separate Homo sapiens and Drosophila melanogaster. Eighty-seven percent have one or more fruit fly homologs and 76% have at least one candidate functional ortholog. We propose that D. melanogaster can be used in a systematic manner to study MR and possibly to develop bioassays for therapeutic drug discovery. We selected 42 Drosophila orthologs as most likely to reveal molecular and cellular mechanisms of nervous system development or plasticity relevant to MR.
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Affiliation(s)
- Jennifer K Inlow
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson 85721-0077, USA
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Hribar M, Bloc A, Medilanski J, Nüsch L, Eder-Colli L. Voltage-gated K+ current: a marker for apoptosis in differentiating neuronal progenitor cells? Eur J Neurosci 2004; 20:635-48. [PMID: 15255975 DOI: 10.1111/j.1460-9568.2004.03520.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We investigated apoptosis during early stages of in vitro differentiation of neuronal precursors generated by embryonic day 14 (E14) mouse striata stem cells. Differentiation was in conditions of suboptimal growth factor supply. Apoptosis reached 10-15% of cells and affected proliferating as well as postmitotic cells, including TUJ1-positive cells. Inhibition of apoptosis led to an increased proportion of TUJ1-positive cells generated by stem cells. K(+) current was reported to be related to apoptosis. Outward K(+) currents were present in differentiating neuronal precursors that were consistent with delayed rectifier and transient A-type currents. The amplitude of the delayed rectifier current varied during the first 4 days of stem cell differentiation. Current amplitude was greatly increased in the presence of staurosporine but reduced at elevated extracellular K(+) concentration. In addition, the amplitude of the current was significantly diminished by inhibiting several caspases, but not caspase 8. In Bax knock-out transgenic neuronal precursors, K(+) current was not decreased after the first day but at later stages of cell differentiation. At this early stage, apoptosis of proliferating cells and of TUJ1-positive cells was not reduced by the absence of Bax, but was by caspase 9 inhibition. Thus, activation of a delayed rectifier K(+) current in differentiating stem cells is related to apoptosis. Recordings of this current revealed that apoptosis at early stages of neuronal differentiation occurred in two phases that did not exhibit similar dependence on the proapoptotic protein Bax and that probably used different pathways.
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Affiliation(s)
- Marusa Hribar
- Department of Basic Neurosciences, Centre Médical Universitaire, 1, rue Michel Servet, 1211 Geneva 4, Switzerland
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40
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Menu dit Huart L, Lorentz O, Goureau O, Léveillard T, Sahel JA. DNA repair in the degenerating mouse retina. Mol Cell Neurosci 2004; 26:441-9. [PMID: 15234348 DOI: 10.1016/j.mcn.2004.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2003] [Revised: 04/02/2004] [Accepted: 04/02/2004] [Indexed: 11/23/2022] Open
Abstract
In light of different recent results suggesting that the adult mammalian central nervous system can produce new neurons, possibly as an endogenous repair mechanism, we investigated whether neurogenesis occurs in response to photoreceptor degeneration in the rd1 mouse, a model of human-inherited retinal dystrophy. Bromodeoxy-Uridine (BrdU) incorporation and proliferating cell nuclear antigen (PCNA) expression experiments detected cell proliferation in the extreme peripheral retina, in both wt and rd1 retina, independent of degeneration. BrdU incorporation and PCNA expression also occurred in rd1 photoreceptors. Our results strongly suggest that these photoreceptors undergo DNA repair: p53, PCNA, and DNA ligase IV are expressed before photoreceptor death, consistent with a model where photoreceptors expressing the rd1 mutation activate a process of DNA repair but which is overwhelmed by the disease mutation leading to apoptotic death. The existence of such a balance offers potential new targets for neuroprotective approaches.
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Affiliation(s)
- L Menu dit Huart
- Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, INSERM U 592 Université Pierre et Marie Curie, Hôpital Saint-Antoine, Bâtiment Kourilsky, 75571 Paris Cedex 12, France
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41
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Gohlke JM, Griffith WC, Faustman EM. The role of cell death during neocortical neurogenesis and synaptogenesis: implications from a computational model for the rat and mouse. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2004; 151:43-54. [PMID: 15246691 DOI: 10.1016/j.devbrainres.2004.03.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/29/2004] [Indexed: 11/23/2022]
Abstract
We are quantitatively evaluating the acquisition of neocortical neurons through key stages of development including neurogenesis, migration, and synaptogenesis. Here we expand upon a previous computational model describing neocortical neurogenesis in the rat and mouse [Dev. Neurosci. 24 (2002) 467], to include the period of synaptogenesis (P0-P14) when programmed cell death (PCD) is known to play a major role in shaping the neocortex. We also quantitatively evaluate differing hypotheses on the role of cell death during neurogenesis. This new model construct allows prediction of acquisition of adult neuronal number in the rat and mouse neocortex from the beginning of neurogenesis through synaptogenesis. The mathematical model output is validated by independently derived stereologically determined neuron number estimates in the adult rat and mouse. Simulations suggest cell death during synaptogenesis reduces the neocortical neuronal population by 20-30%, while cell death of progenitor cells and newly formed neurons during neurogenesis may reduce output by as much as 24%. However, higher death rates during neurogenesis as suggested by some research would deplete the progenitor population, not allowing for the vast expansion that is the hallmark of the mammalian neocortex. Furthermore, our simulations suggest the clearance time of dying neurons labeled by TUNEL or pyknosis is relatively short, between 1 and 4 h, corroborating experimental research. This novel mathematical model for adult neocortical neuronal acquisition allows for in silico analysis of normal and perturbed states of neocortical development as well as interspecies and evolutionary analyses of neocortical development.
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Affiliation(s)
- Julia M Gohlke
- Center for Child Environmental Health Risks Research, Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105-6099, USA
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Abstract
Abstract
Affecting 1-3% of the population, mental retardation (MR) poses significant challenges for clinicians and scientists. Understanding the biology of MR is complicated by the extraordinary heterogeneity of genetic MR disorders. Detailed analyses of >1000 Online Mendelian Inheritance in Man (OMIM) database entries and literature searches through September 2003 revealed 282 molecularly identified MR genes. We estimate that hundreds more MR genes remain to be identified. A novel test, in which we distributed unmapped MR disorders proportionately across the autosomes, failed to eliminate the well-known X-chromosome overrepresentation of MR genes and candidate genes. This evidence argues against ascertainment bias as the main cause of the skewed distribution. On the basis of a synthesis of clinical and laboratory data, we developed a biological functions classification scheme for MR genes. Metabolic pathways, signaling pathways, and transcription are the most common functions, but numerous other aspects of neuronal and glial biology are controlled by MR genes as well. Using protein sequence and domain-organization comparisons, we found a striking conservation of MR genes and genetic pathways across the ∼700 million years that separate Homo sapiens and Drosophila melanogaster. Eighty-seven percent have one or more fruit fly homologs and 76% have at least one candidate functional ortholog. We propose that D. melanogaster can be used in a systematic manner to study MR and possibly to develop bioassays for therapeutic drug discovery. We selected 42 Drosophila orthologs as most likely to reveal molecular and cellular mechanisms of nervous system development or plasticity relevant to MR.
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Affiliation(s)
- Jennifer K Inlow
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, Arizona 85721-0077
| | - Linda L Restifo
- Arizona Research Laboratories Division of Neurobiology, University of Arizona, Tucson, Arizona 85721-0077
- Department of Neurology, University of Arizona, Tucson, Arizona 85721-0077
- Genetics Graduate Interdisciplinary Program, University of Arizona, Tucson, Arizona 85721-0077
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Besirli CG, Deckwerth TL, Crowder RJ, Freeman RS, Johnson EM. Cytosine arabinoside rapidly activates Bax-dependent apoptosis and a delayed Bax-independent death pathway in sympathetic neurons. Cell Death Differ 2003; 10:1045-58. [PMID: 12934079 DOI: 10.1038/sj.cdd.4401259] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Cytosine arabinoside (ara-C) is a nucleoside analog used in the treatment of hematologic malignancies. One of the major side effects of ara-C chemotherapy is neurotoxicity. In this study, we have further characterized the cell death induced by ara-C in sympathetic neurons. Similar to neurons undergoing trophic factor deprivation-induced apoptosis, ara-C-exposed neurons became hypometabolic before death and upregulated c-myb, c-fos, and Bim. Bax deletion delayed, but did not prevent, ara-C toxicity. Neurons died by apoptosis, indicated by the release of mitochondrial cytochrome-c and caspase-3 activation. p53-deficient neurons demonstrated decreased sensitivity to ara-C, but neither p53 nor multiple p53-regulated genes were induced. Mature neurons showed increased ara-C resistance. These results demonstrate that molecular mechanisms underlying ara-C-induced death are similar to those responsible for trophic factor deprivation-induced apoptosis. However, substantial differences in neuronal death after these two distinct stress stimuli exist since ara-C toxicity, unlike the developmental death, can proceed in the absence of Bax.
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Affiliation(s)
- C G Besirli
- Departments of Neurology and Molecular Biology & Pharmacology, Washington University School of Medicine, Saint Louis, MO 63110, USA
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Lossi L, Merighi A. In vivo cellular and molecular mechanisms of neuronal apoptosis in the mammalian CNS. Prog Neurobiol 2003; 69:287-312. [PMID: 12787572 DOI: 10.1016/s0301-0082(03)00051-0] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Apoptosis has been recognized to be an essential process during neural development. It is generally assumed that about half of the neurons produced during neurogenesis die before completion of the central nervous system (CNS) maturation, and this process affects nearly all classes of neurons. In this review, we discuss the experimental data in vivo on naturally occurring neuronal death in normal, transgenic and mutant animals, with special attention to the cerebellum as a study model. The emerging picture is that of a dual wave of apoptotic cell death affecting central neurons at different stages of their life. The first wave consists of an early neuronal death of proliferating precursors and young postmitotic neuroblasts, and appears to be closely linked to cell cycle regulation. The second wave affects postmitotic neurons at later stages, and is much better understood in functional terms, mainly on the basis of the neurotrophic concept in its broader definition. The molecular machinery of late apoptotic death of postmitotic neurons more commonly follows the mitochondrial pathway of intracellular signal transduction, but the death receptor pathway may also be involved.Undoubtedly, analysis of naturally occurring neuronal death (NOND) in vivo will offer a basis for parallel and future studies aiming to elucidate the mechanisms of pathologic neuronal loss occurring as the result of conditions such as neurodegenerative disorders, trauma or ischemia.
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Affiliation(s)
- L Lossi
- Department of Veterinary Morphophysiology, University of Torino, Via Leonardo da Vinci 44, I-10095 (TO), Grugliasco, Italy.
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Walker PR, Carson C, Leblanc J, Sikorska M. Labeling DNA damage with terminal transferase. Applicability, specificity, and limitations. Methods Mol Biol 2002; 203:3-19. [PMID: 12073451 DOI: 10.1007/978-1-59259-179-4_1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Affiliation(s)
- P Roy Walker
- Apoptosis Research Group, Institute for Biological Sciences, NRC, Ottawa, Canada
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Klocke BJ, Latham CB, D'Sa C, Roth KA. p53 deficiency fails to prevent increased programmed cell death in the Bcl-X(L)-deficient nervous system. Cell Death Differ 2002; 9:1063-8. [PMID: 12232794 DOI: 10.1038/sj.cdd.4401067] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2002] [Accepted: 04/05/2002] [Indexed: 11/08/2022] Open
Abstract
Bcl-X(L) mice display a similar neurodevelopmental phenotype as rb, DNA ligase IV, and XRCC4 mutant embryos, suggesting that endogenous Bcl-X(L) expression may protect immature neurons from death caused by DNA damage and/or cell cycle dysregulation. To test this hypothesis, we generated bcl-x/p53 double mutants and examined neuronal cell death in vivo and in vitro. Bcl-X(L)-deficient primary telencephalic neuron cultures were highly susceptible to the apoptotic effects of cytosine arabinoside (AraC), a known genotoxic agent. In contrast, neurons lacking p53, or both Bcl-X(L) and p53, were markedly, and equivalently, resistant to AraC-induced caspase-3 activation and death in vitro indicating that Bcl-X(L) lies downstream of p53 in DNA damage-induced neuronal death. Despite the ability of p53 deficiency to protect Bcl-X(L)-deficient neurons from DNA damage-induced apoptosis in vitro, p53 deficiency had no effect on the increased caspase-3 activation and neuronal cell death observed in the developing Bcl-X(L)-deficient nervous system. These findings suggest that Bcl-X(L) expression in the developing nervous system critically regulates neuronal responsiveness to an apoptotic stimulus other than inadequate DNA repair or cell cycle abnormalities.
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Affiliation(s)
- B J Klocke
- Department of Pathology and Immunology Division of Neuropathology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Cai L, Hayes NL, Takahashi T, Caviness VS, Nowakowski RS. Size distribution of retrovirally marked lineages matches prediction from population measurements of cell cycle behavior. J Neurosci Res 2002; 69:731-44. [PMID: 12205666 DOI: 10.1002/jnr.10398] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mechanisms that regulate neuron production in the developing mouse neocortex were examined by using a retroviral lineage marking method to determine the sizes of the lineages remaining in the proliferating population of the ventricular zone during the period of neuron production. The distribution of clade sizes obtained experimentally in four different injection-survival paradigms (E11-E13, E11-E14, E11-E15, and E12-E15) from a total of over 500 labeled lineages was compared with that obtained from three models in which the average behavior of the proliferating population [i.e., the proportion of cells remaining in the proliferative population (P) vs. that exiting the proliferative population (Q)] was quantitatively related to lineage size distribution. In model 1, different proportions of asymmetric, symmetric terminal, and symmetric nonterminal cell divisions coexisted during the entire developmental period. In model 2, the developmental period was divided into two epochs: During the first, asymmetric and symmetric nonterminal cell divisions occurred, but, during the second, asymmetric and symmetric terminal cell divisions occurred. In model 3, the shifts in P and Q are accounted for by changes in the proportions of the two types of symmetric cell divisions without the inclusion of any asymmetric cell divisions. The results obtained from the retroviral experiments were well accounted for by model 1 but not by model 2 or 3. These findings demonstrate that: 1) asymmetric and both types of symmetric cell divisions coexist during the entire period of neurogenesis in the mouse, 2) neuron production is regulated in the proliferative population by the independent decisions of the two daughter cells to reenter S phase, and 3) neurons are produced by both asymmetric and symmetric terminal cell divisions. In addition, the findings mean that cell death and/or tangential movements of cells in the proliferative population occur at only a low rate and that there are no proliferating lineages "reserved" to make particular laminae or cell types.
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Affiliation(s)
- Li Cai
- Department of Neuroscience and Cell Biology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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Abstract
Neural stem cells (NSCs) have the ability to self-renew, and are capable of differentiating into neurones, astrocytes and oligodendrocytes. Such cells have been isolated from the developing brain and more recently from the adult central nervous system. This review aims to provide an overview of the current research in this evolving area. There is now increasing knowledge of the factors controlling the division and differentiation of NSCs during normal brain development. In addition, the cues for differentiation in vitro, and the possibility of transdifferentiation are reviewed. The discovery of these cells in the adult brain has encouraged research into their role during neurogenesis in the normal mature brain and after injury. Lastly other sources of neural precursors are discussed, and the potential for stem cells to be used in cell replacement therapy for brain injury or degenerative brain diseases with a particular emphasis on cerebral ischaemia and Parkinson's disease.
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Affiliation(s)
- Nigel L Kennea
- Weston Laboratory, Institute of Reproductive and Developmental Biology, Division of Paediatrics, Obstetrics and Gynaecology, Imperial College of Science, Technology and Medicine, London W12 0NN, UK
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Chechlacz M, Naegele J. Genetics of childhood disorders: XL. Stem cell research, part 4: neural horticulture. J Am Acad Child Adolesc Psychiatry 2002; 41:882-5. [PMID: 12108815 DOI: 10.1097/00004583-200207000-00023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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50
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Hicar MD, Robinson ML, Wu LC. Embryonic expression and regulation of the large zinc finger protein KRC. Genesis 2002; 33:8-20. [PMID: 12001065 DOI: 10.1002/gene.10084] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
KRC fusion proteins bind to the kappaB enhancer motif and to the signal sequences of V(D)J recombination. Here we have characterized endogenous KRC in mouse embryos and lymphoma cell lines. Starting from midgestation, neuronal- and lymphoid-restricted expression of KRC was observed from the dorsal root ganglia, trigeminal ganglion, thymus, and cerebral cortex. Several B-cell lines produced an alternatively spliced KRC transcript of 4.5 kb and a 115-kDa DNA-binding protein isoform. Additionally, that KRC transcript was induced by lipopolysaccharide, a potent activator of cells in immunity and inflammation. In genetic-engineered B cells stably transfected with inducible expression vectors for the recombination activating genes RAG1, RAG2, or both, the avidity of KRC to DNA was markedly decreased when RAG1 and RAG2 were overexpressed. We hypothesize that KRC may function in developing thymocytes and neurons, where its role might be transcription regulation or DNA recombination.
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Affiliation(s)
- Mark D Hicar
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, College of Medicine and Public Health, Columbus 43210, USA
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