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Mouse (Mus Musculus) Embryonic Cerebral Cortex Cell Death Caused by Carbofuran Insecticide Exposure. J Vet Res 2019; 63:413-421. [PMID: 31572823 PMCID: PMC6749746 DOI: 10.2478/jvetres-2019-0040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 07/02/2019] [Indexed: 11/27/2022] Open
Abstract
Introduction The aim of the study was to describe the process of neuron death in the cerebral cortex caused by embryonic carbofuran exposure. Material and Methods 81 mouse foetuses from 27 breeding mice were used in the study. Carbofuran was administered by gavage from the 6th to the 15th day of gestation to two groups: one at 0.0208 and the other at 0.0417 mg/kg b.w. On the 17th day, the mice were sacrificed and the foetuses were taken to measure the ROS (malondialdehyde/MDA and superoxide dismutase/SOD) activity in brain tissue, the number of apoptotic embryonic cerebral cortex neurons using a TUNEL assay, and necrotic cells using HE staining. Examination of p53 and caspase 3 expression was done by immunohistochemistry. Data were analysed using analysis of variance (ANOVA) and Duncan’s test. Results Increased activity of cerebral ROS characterised by significant elevation of the MDA level (P < 0.05), decreased SOD (P < 0.01), increased p53 and caspase 3 expression, and cerebral cortical neuron death either by necrosis or apoptosis (P < 0.05) were found. At the low dose carbofuran increased expression of p53, caspase 3, and apoptosis. At the high dose it increased levels of MDA and necrosis. Conclusion Increased expression of p53 and caspase 3 and apoptosis indicated that carbofuran may cause apoptosis through the intrinsic pathway. The increased apoptosis grants an opportunity to prevent and treat the effect of ROS due to gestational carbofuran exposure.
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Rogers HA, Chapman R, Kings H, Allard J, Barron-Hastings J, Pajtler KW, Sill M, Pfister S, Grundy RG. Limitations of current in vitro models for testing the clinical potential of epigenetic inhibitors for treatment of pediatric ependymoma. Oncotarget 2018; 9:36530-36541. [PMID: 30559935 PMCID: PMC6284855 DOI: 10.18632/oncotarget.26370] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 11/01/2018] [Indexed: 12/12/2022] Open
Abstract
Background Epigenetic modifications have been shown to play an important role in the classification and pathogenesis of the pediatric brain tumor ependymoma, suggesting they are a potential therapeutic target. Results Agents targeting epigenetic modifications inhibited the growth and induced the death of ependymoma cells with variable efficiency. However, this was often not at clinically achievable doses. Additionally, DNA methylation profiling revealed a lack of similarity to primary ependymomas suggesting alterations were induced during culture. Toxicity to fetal neural stem cells was also seen at similar drug concentrations Conclusions Agents targeting epigenetic modifications were able to inhibit the growth and induced the death of ependymoma cells grown in vitro. However, many agents were only active at high doses, outside clinical ranges, and also resulted in toxicity to normal brain cells. The lack of similarity in DNA methylation profiles between cultured cells and primary ependymomas questions the validity of using in vitro cultured cells for pre-clinical analysis of agents targeting epigenetic mechanisms and suggests further investigation using models that are more appropriate should be undertaken before agents are taken forward for clinical testing. Materials and Methods The effects of agents targeting epigenetic modifications on the growth and death of a panel of ependymoma cell lines was investigated, as well as toxicity to normal fetal neural stem cells. The ependymoma cell lines were characterized using DNA methylation profiling.
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Affiliation(s)
- Hazel Anne Rogers
- Children's Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Rebecca Chapman
- Children's Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Holly Kings
- Children's Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Julie Allard
- Children's Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Jodie Barron-Hastings
- Children's Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - Kristian W Pajtler
- Hopp Children's Cancer Centre at the NCT (KiTZ), Heidelberg, Germany.,German Cancer Research Centre (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany.,Department of Haematology and Oncology, University Hospital, Heidelberg, Germany
| | - Martin Sill
- Hopp Children's Cancer Centre at the NCT (KiTZ), Heidelberg, Germany.,German Cancer Research Centre (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany
| | - Stefan Pfister
- Hopp Children's Cancer Centre at the NCT (KiTZ), Heidelberg, Germany.,German Cancer Research Centre (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany.,Department of Haematology and Oncology, University Hospital, Heidelberg, Germany
| | - Richard Guy Grundy
- Children's Brain Tumour Research Centre, School of Medicine, University of Nottingham, Nottingham, UK
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'Memory and molecular turnover,' 30 years after inception. Epigenetics Chromatin 2014; 7:37. [PMID: 25525471 PMCID: PMC4269865 DOI: 10.1186/1756-8935-7-37] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 11/28/2014] [Indexed: 12/28/2022] Open
Abstract
In 1984 Sir Francis Crick hypothesized that memory is recorded in the brain as reversible modifications to DNA and protein, but acknowledged that most biomolecules turn over too rapidly to account for long-term memories. To accommodate this possible paradox he modeled an enzymatic mechanism to maintain modifications on hemi-modified multimeric symmetrical molecules. While studies on the turnover of chromatin modifications that may be involved in memory are in their infancy, an exploration of his model in the light of modern epigenetics produced somewhat surprising results. The molecular turnover rates for two classes of chromatin modifications believed to record and store durable memories were approximated from experiments using diverse approaches and were found to be remarkably short. The half-lives of DNA cytosine methylation and post-translationally modified nucleosomal histones are measured in hours and minutes, respectively, for a subset of sites on chromatin controlling gene expression. It appears likely that the turnover of DNA methylation in the brain and in neurons, in particular, is even more rapid than in other cell types and organs, perhaps accommodating neuronal plasticity, learning, and memory. The machinery responsible for the rapid turnover of DNA methylation and nucleosomal histone modifications is highly complex, partially redundant, and appears to act in a sequence specific manner. Molecular symmetry plays an important part in maintaining site-specific turnover, but its particular role in memory maintenance is unknown. Elucidating Crick’s paradox, the contradiction between rapid molecular turnover of modified biomolecules and long-term memory storage, appears fundamental to understanding cognitive function and neurodegenerative disease.
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Ueno M, Yamashita T. Bidirectional tuning of microglia in the developing brain: from neurogenesis to neural circuit formation. Curr Opin Neurobiol 2014; 27:8-15. [PMID: 24607651 DOI: 10.1016/j.conb.2014.02.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 01/15/2014] [Accepted: 02/06/2014] [Indexed: 12/14/2022]
Abstract
The developing brain employs multi-step processes to construct neural circuitry. Recent studies have highlighted that microglia, traditionally known to be the resident immune cells in the brain, have essential roles in these processes, which range from neurogenesis to establishing synaptic connections. Microglia play bidirectional roles for maintaining proper circuitry: eliminating unnecessary cells, axons, and synapses, while supporting the neighboring ones. Although these processes are performed in different parts of the neuron, similar molecular mechanisms are possibly involved. This paper reviews recent progress on the knowledge of the roles of microglia in brain development, and further discusses the application of this knowledge in therapies for brain disorders and injuries.
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Affiliation(s)
- Masaki Ueno
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, United States; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita-shi, Osaka 565-0871, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 5 Sanbancho, Chiyoda-ku, Tokyo, Japan.
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Doi K. Mechanisms of neurotoxicity induced in the developing brain of mice and rats by DNA-damaging chemicals. J Toxicol Sci 2012; 36:695-712. [PMID: 22129734 DOI: 10.2131/jts.36.695] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
It is not widely known how the developing brain responds to extrinsic damage, although the developing brain is considered to be sensitive to diverse environmental factors including DNA-damaging agents. This paper reviews the mechanisms of neurotoxicity induced in the developing brain of mice and rats by six chemicals (ethylnitrosourea, hydroxyurea, 5-azacytidine, cytosine arabinoside, 6-mercaptopurine and etoposide), which cause DNA damage in different ways, especially from the viewpoints of apoptosis and cell cycle arrest in neural progenitor cells. In addition, this paper also reviews the repair process following damage in the developing brain.
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Affiliation(s)
- Kunio Doi
- Nippon Institute for Biological Science, Ome, Tokyo, Japan.
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Ueno M, Yamashita T. Strategies for regenerating injured axons after spinal cord injury - insights from brain development. Biologics 2011; 2:253-64. [PMID: 19707358 PMCID: PMC2721354 DOI: 10.2147/btt.s2715] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Axonal regeneration does not occur easily after an adult central nervous system (CNS) injury. Various attempts have partially succeeded in promoting axonal regeneration after the spinal cord injury (SCI). Interestingly, several recent therapeutic concepts have emerged from or been tightly linked to the researches on brain development. In a developing brain, remarkable and dynamic axonal elongation and sprouting occur even after the injury; this finding is essential to the development of a therapy for SCI. In this review, we overview the revealed mechanism of axonal tract formation and plasticity in the developing brain and compare the differences between a developing brain and a lesion site in an adult brain. One of the differences is that mature glial cells participate in the repair process in the case of adult injuries. Interestingly, these cells express inhibitory molecules that impede axonal regeneration such as myelin-associated proteins and the repulsive guidance molecules found originally in the developing brain for navigating axons to specific routes. Some reports have clearly elucidated that any treatment designed to suppress these inhibitory cues is beneficial for promoting regeneration and plasticity after an injury. Thus, understanding the developmental process will provide us with an important clue for designing therapeutic strategies for recovery from SCI.
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Affiliation(s)
- Masaki Ueno
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita-shi, Osaka 565-0871, Japan
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Yamaguchi T, Kanemitsu H, Yamamoto S, Komatsu M, Uemura H, Tamura K, Shirai T. N,N'-Bis(2-chloroethyl)-N-nitrosourea (BCNU)-induced Apoptosis of Neural Progenitor Cells in the Developing Fetal Rat Brain. J Toxicol Pathol 2010; 23:25-30. [PMID: 22272008 PMCID: PMC3234648 DOI: 10.1293/tox.23.25] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 10/13/2009] [Indexed: 11/23/2022] Open
Abstract
N,N’-bis(2-chloroethyl)-N-nitrosourea
(BCNU) is one of the major drugs used in chemotherapy against malignant
gliomas due to its effects, such as induction of bifunctional alkylation of
DNA and formation of interstrand DNA cross-linkages, and induces cortical
malformations in the fetal and neonatal rat brain. In this study, pregnant
rats were treated with 7.5 mg/kg of BCNU on gestational day 13 (GD 13), and
their fetuses were collected from 12 to 72 hours after BCNU treatment in
order to examine the timecourses of morphological and immunohistochemical
changes in neural progenitor cells in the developing brain. The number of
pyknotic cells in the telencephalon peaked at 24 h and then gradually
decreased until 72 h. The majority of these pyknotic cells were positive
for cleaved caspase-3, a key executioner of apoptosis. The pyknotic cells
showed the ultrastructural characteristics of apoptosis. The number of
p53-positive cells began to increase prior to the appearance of apoptotic
cells and p21-positive cells. The number of phosphorylated-histone
H3-positive cells (mitotic cells) decreased from 24 to 36 h. The number of
Iba1-positive cells (microglial cells) in the telencephalon increased from
12 to 48 h. These results suggest that BCNU induces p53-dependent apoptosis
and reduces proliferative activity, resulting in reduction of the weight of
the telencephalon and the thickness of the telencephalic wall in the fetal
brain. This study will help to clarify the mechanisms of BCNU-induced fetal
brain toxicity.
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Affiliation(s)
- Tsuyoshi Yamaguchi
- Bozo Research Center Inc., Gotemba-shi, Shizuoka 412-0039,
Japan
- Department of Experimental Pathology and Tumor Biology,
Nagoya City University Graduate School of Medical Sciences, Nagoya
467-8601, Japan
| | | | - Satoshi Yamamoto
- Bozo Research Center Inc., Gotemba-shi, Shizuoka 412-0039,
Japan
| | - Masahiko Komatsu
- Bozo Research Center Inc., Gotemba-shi, Shizuoka 412-0039,
Japan
| | - Hiroyuki Uemura
- Bozo Research Center Inc., Gotemba-shi, Shizuoka 412-0039,
Japan
| | - Kazutoshi Tamura
- Bozo Research Center Inc., Gotemba-shi, Shizuoka 412-0039,
Japan
| | - Tomoyuki Shirai
- Department of Experimental Pathology and Tumor Biology,
Nagoya City University Graduate School of Medical Sciences, Nagoya
467-8601, Japan
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