• Journal of Life Science
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• v.27 no.6
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• pp.623-631
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• 2017

In the subventricular zone (SVZ) and the subgranular zone of the brain, neurogenesis occurs throughout one's lifespan. Neural stem cells (NSCs) in these regions divide to maintain their stem cell pools as well as differentiate into neurons and glial cells. To monitor cell division, a thymidine analogue such as 5-ethynyl-2'-deoxyuridine (EdU) has been used. In some cases, EdU was applied to label newly born neurons. Here, we report about the effects of EdU on the proliferation and differentiation of NSCs cultured from mouse SVZ. First, when NSCs were cultured in a proliferation medium containing EdU for 24 hr, they did not generate any neurons under the following differentiation conditions. When EdU was applied to the proliferating NSCs for 1 hr prior to differentiation, neurogenesis was still substantially reduced. Second, EdU decreased cell proliferation of NSCs in dose- and time-dependent manners. Finally, EdU inhibited differentiation into oligodendrocyte lineage, while the number of glial fibrillary acidic protein (GFAP)-positive astrocytes increased. To our knowledge, these findings are the first to show the effects of EdU on the differentiation of SVZ NSCs and suggest that cell division is necessary for differentiation into neurons and oligodendrocytes.

• Proceedings of the KSMRM Conference
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• 1999.04a
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• pp.99-108
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• 1999

선천성 대사 이상은 다양한 뇌질환으로 나타낸다. 일반적으로 이 질환들은 하나 또는 둘이상의 대사경로에 대한 생화학적 이상에 원인이 있다. 정상적 생화학적 산물의 결핍이나 비정상적 산물의 축적에 의한 뇌기능 이상에 의해 임상증상이 나타내게 되는데 그 증상은 대개 경기, 경직성, 발육지연 등으로 비특이적이고 영상소견도 마찬가지로 비특이적이다. 대사 이상에 있어서의 신경병변은 일부 뇌백질을 주로 침범하는 경우를 제외하면 대부분 뇌백질을 침범하고 따라서 일반적으로 일차성 뇌백질 질환이 대사성 뇌질환을 일컫는다고 할 수가 있다. 뇌백질 질환은 뇌백질의 구성원중 가장 큰 부분을 차지하는 수초(myelin)를 침범하는 질환을 일컫는다. 중추신경계의 백질은 수초로 싸여있는 축삭(axon)과 선경교세포 (neuroglial cell) 및 혈관 등으로 구성되어 있으며, 이중 대부분을 수초가 차지하고 이 수초로 인하여 정상 뇌백질이 흰색을 나타낸다. 백질내의 신경교세포로는 성상세포 (astrocyte) 와 핍지세포 (oligodendrocyte)가 있으며 신 경교세포의 가장 중요한 기능은 핍지세포에 의한 축삭의 외피화 (ensheathment) 즉, 수초이다. 수초는 핍지세포의 세포질 돌기 (cytoplasmic process)의 일부이며 따라서 수초의 생존과 대사는 핍지세포와 운명을 같이한다. 일반적으로 세포의 생존, 대사와 가장 관련있는 기능은 세포질내에 함유되어 있는 구조물인 소기관(organelle)에 의하여 수행된다. 따라서, 비록 모든 소기관들이 백질 질환을 이르키는데 직접 연관되어 있지는 않더라도 수초의 생존과 대사에는 핍지세포의 소기관들이 매우 중요한 역할을 하게 된다. 세포질내 중요한 소기관으로는 세포 막, 미토콘드리아 (mitochondria), endoplasmic reticulum, Golgi 체, lysosome, peroxisome 그리고 세포질등이 있으며, 이들중에서 lysosomes, peroxisomes, 그리고 미토콘드리아가 특정한 유전성 백질질환에 중요한 역할을 하는 것이 밝혀졌다. 이러한 질환들은 최소한 각 소기관에 의한 질환군으로 분류될 수 있다.

• Clinical and Experimental Pediatrics
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• v.57 no.3
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• pp.101-109
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• 2014

The use of glucocorticoids (GCs) in the perinatal period is suspected of being associated with adverse effects on long-term neurodevelopmental outcomes for preterm infants. Repeated administration of antenatal GCs to mothers at risk of preterm birth may adversely affect fetal growth and head circumference. Fetal exposure to excess GCs during critical periods of brain development may profoundly modify the limbic system (primarily the hippocampus), resulting in long-term effects on cognition, behavior, memory, co-ordination of the autonomic nervous system, and regulation of the endocrine system later in adult life. Postnatal GC treatment for chronic lung disease in premature infants, particularly involving the use of dexamethasone, has been shown to induce neurodevelopmental impairment and increases the risk of cerebral palsy. In contrast to studies involving postnatal dexamethasone, long-term follow-up studies for hydrocortisone therapy have not revealed adverse effects on neurodevelopmental outcomes. In experimental studies on animals, GCs has been shown to impair neurogenesis, and induce neuronal apoptosis in the immature brains of newborn animals. A recent study has demonstrated that dexamethasone-induced hypomyelination may result from the apoptotic degeneration of oligodendrocyte progenitors in the immature brain. Thus, based on clinical and experimental studies, there is enough evidence to advice caution regarding the use of GCs in the perinatal period; and moreover, the potential long-term effects of GCs on brain development need to be determined.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.6
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• pp.1640-1646
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• 2005

An oriental medicinal drugs Jahageo (JHG, Hominis placenta) were examined to determine its effects on the responsiveness of central nervous system neurons after injury. We found that JHG was involved in neurite outgrowth of DRG sensory axons. JHG treatment also increased expression of axonal growth-associated protein GAP-43 in DRG sensory neurons after sciatic nerve injury and in the injured spinal cord. JHG treatment during the spinal cord injury increased induction levels of cell division cycle 2 (Cdc2) protein in DRG as well as in the spinal cord. Histochemical investigation showed that induced Cdc2 in the injured spinal cord was found in non-neuronal cells. These results suggest that JHG regulates activities of non-neuronal cells such as oligodendrocyte and astrocyte in responses to spinal cord injury and protects neuronal responsiveness after axonal damage.

• Biomolecules & Therapeutics
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• v.25 no.3
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• pp.231-238
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• 2017

Myelin is a specialized structure of the nervous system that both enhances electrical conductance and insulates neurons from external risk factors. In the central nervous system, polarized oligodendrocytes form myelin by wrapping processes in a spiral pattern around neuronal axons through myelin-related gene regulation. Since these events occur at a distance from the cell body, post-transcriptional control of gene expression has strategic advantage to fine-tune the overall regulation of protein contents in situ. Therefore, many research interests have been focused to identify RNA binding proteins and their regulatory mechanism in myelinating compartments. Fragile X mental retardation protein (FMRP) is one such RNA binding protein, regulating its target expression by translational control. Although the majority of works on FMRP have been performed in neurons, it is also found in the developing or mature glial cells including oligodendrocytes, where its function is not well understood. Here, we will review evidences suggesting abnormal translational regulation of myelin proteins with accompanying white matter problem and neurological deficits in fragile X syndrome, which can have wider mechanistic and pathological implication in many other neurological and psychiatric disorders.

• Biomolecules & Therapeutics
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• v.27 no.2
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• pp.152-159
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• 2019

Multiple sclerosis (MS) is an autoimmune disease characterized by progressive neuronal loss, neuroinflammation, axonal degeneration, and demyelination. Previous studies have reported that 6-shogaol, a major constituent of ginger (Zingiber officinale rhizome), and its biological metabolite, 6-paradol, have anti-inflammatory and anti-oxidative properties in the central nervous system (CNS). In the present study, we investigated whether 6-shogaol and 6-paradol could ameliorate against experimental autoimmune encephalomyelitis (EAE), a mouse model of MS elicited by myelin oligodendrocyte glycoprotein ($MOG_{35-55}$) peptide immunization with injection of pertussis toxin. Once-daily administration of 6-shogaol and 6-paradol (5 mg/kg/day, p.o.) to symptomatic EAE mice significantly alleviated clinical signs of the disease along with remyelination and reduced cell accumulation in the white matter of spinal cord. Administration of 6-shogaol and 6-paradol into EAE mice markedly reduced astrogliosis and microglial activation as key features of immune responses inside the CNS. Furthermore, administration of these two molecules significantly suppressed expression level of tumor necrosis $factor-{\alpha}$, a major proinflammatory cytokine, in EAE spinal cord. Collectively, these results demonstrate therapeutic efficacy of 6-shogaol or 6-paradol for EAE by reducing neuroinflammatory responses, further indicating the therapeutic potential of these two active ingredients of ginger for MS.

• Journal of Embryo Transfer
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• v.32 no.2
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• pp.39-45
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• 2017

Mesenchymal stem cells (MSCs) have been considered an alternative source of neuronal lineage cells, which are difficult to isolate from brain and expand in vitro. Previous studies have reported that MSCs expressing Nestin ($Nestin^+$ MSCs), a neuronal stem/progenitor cell marker, exhibit increased transcriptional levels of neural development-related genes, indicating that $Nestin^+$ MSCs may exert potential with neurogenic differentiation. Accordingly, we investigated the effects of the presence of $Nestin^+$ MSCs in bone-marrow-derived primary cells (BMPCs) on enhanced neurogenic differentiation of BMPCs by identifying the presence of $Nestin^+$ MSCs in uncultured and cultured BMPCs. The percentage of $Nestin^+$ MSCs in BMPCs was measured per passage by double staining with Nestin and CD90, an MSC marker. The efficiency of neurogenic differentiation was compared among passages, revealing the highest and lowest yields of $Nestin^+$ MSCs. The presence of $Nestin^+$ MSCs was identified in BMPCs before in vitro culture, and the highest and lowest percentages of $Nestin^+$ MSCs in BMPCs was observed at the third (P3) and fifth passages (P5). Moreover, significantly the higher efficiency of differentiation into neurons, oligodendrocyte precursor cells and astrocytes was detected in BMPCs at P3, compared with P5. In conclusion, these results demonstrate that neurogenic differentiation can be enhanced by increasing the proportion of $Nestin^+$ MSCs in cultured BMPCs.

• BMB Reports
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• v.51 no.10
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• pp.481-483
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• 2018

Glioblastoma (GBM) is the most common and aggressive form of human adult brain malignancy. The identification of the cell of origin harboring cancer-driver mutations is the fundamental issue for understanding the nature of GBM and developing the effective therapeutic target. It has been a long-term hypothesis that neural stem cells in the subventricular zone (SVZ) might be the origin-of-cells in human glioblastoma since they are known to have life-long proliferative activity and acquire somatic mutations. However, the cell of origin for GBM remains controversial due to lack of direct evidence thereof in human GBM. Our recent study using various sequencing techniques in triple matched samples such as tumor-free SVZ, tumor, and normal tissues from human patients identified the clonal relationship of driver mutations between GBM and tumor-free SVZ harboring neural stem cells (NSCs). Tumor-free SVZ tissue away from the tumor contained low-level GBM driver mutations (as low as 1% allelic frequency) that were found in the dominant clones in its matching tumors. Moreover, via single-cell sequencing and microdissection, it was discovered that astrocyte-like NSCs accumulating driver mutations evolved into GBM with clonal expansion. Furthermore, mutagenesis of cancer-driving genes of NSCs in mice leads to migration of mutant cells from SVZ to distant brain and development of high-grade glioma through the aberrant growth of oligodendrocyte precursor lineage. Altogether, the present study provides the first direct evidence that NSCs in human SVZ is the cell of origin that develops the driver mutations of GBM.

• Molecules and Cells
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• v.37 no.8
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• pp.613-619
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• 2014

The optic nerve often suffers regenerative failure after injury, leading to serious visual impairment such as glaucoma. The main inhibitory factors, including Nogo-A, oligodendrocyte myelin glycoprotein, and myelin-associated glycoprotein, exert their inhibitory effects on axonal growth through the same receptor, the Nogo-66 receptor (NgR). Oncomodulin (OM), a calcium-binding protein with a molecular weight of an ~12 kDa, which is secreted from activated macrophages, has been demonstrated to have high and specific affinity for retinal ganglion cells (RGC) and promote greater axonal regeneration than other known polypeptide growth factors. Protamine has been reported to effectively deliver small interference RNA (siRNA) into cells. Accordingly, a fusion protein of OM and truncated protamine (tp) may be used as a vehicle for the delivery of NgR siRNA into RGC for gene therapy. To test this hypothesis, we constructed OM and tp fusion protein (OM/tp) expression vectors. Using the indirect immunofluorescence labeling method, OM/tp fusion proteins were found to have a high affinity for RGC. The gel shift assay showed that the OM/tp fusion proteins retained the capacity to bind to DNA. Using OM/tp fusion proteins as a delivery tool, the siRNA of NgR was effectively transfected into cells and significantly down-regulated NgR expression levels. More importantly, OM/tp-NgR siRNA dramatically promoted axonal growth of RGC compared with the application of OM/tp recombinant protein or NgR siRNA alone in vitro. In addition, OM/tp-NgR siRNA highly elevated intracellular cyclic adenosine monophosphate (cAMP) levels and inhibited activation of the Ras homolog gene family, member A (RhoA). Taken together, our data demonstrated that the recombinant OM/tp fusion proteins retained the functions of both OM and tp, and that OM/tp-NgR siRNA might potentially be used for the treatment of optic nerve injury.

• Development and Reproduction
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• v.24 no.2
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• pp.135-147
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• 2020

Polyvinylidene fluoride (PVDF) is a stable and biocompatible material that has been broadly used in biomedical applications. Due to its piezoelectric property, the electrospun nanofiber of PVDF has been used to culture electroactive cells, such as osteocytes and cardiomyocytes. Here, taking advantage of the piezoelectric property of PVDF, we have fabricated a PVDF nanofiber scaffolds using an electrospinning technique for differentiating human embryonic stem cells (hESCs) into neural precursors (NPs). Surface coating with a peptide derived from vitronectin enables hESCs to firmly adhere onto the nanofiber scaffolds and differentiate into NPs under dual-SMAD inhibition. Our nanofiber scaffolds supported the differentiation of hESCs into SOX1-positive NPs more significantly than Matrigel. The NPs generated on the nanofiber scaffolds could give rise to neurons, astrocytes, and oligodendrocyte precursors. Furthermore, comparative transcriptome analysis revealed the variable expressions of 27 genes in the nanofiber scaffold groups, several of which are highly related to the biological processes required for neural differentiation. These results suggest that a PVDF nanofiber scaffold coated with a vitronectin peptide can serve as a highly efficient and defined culture platform for the neural differentiation of hESCs.