• Molecules and Cells
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• v.37 no.11
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• pp.767-776
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• 2014

Alzheimer's disease (AD) is clinically characterized with progressive memory loss and cognitive decline. Synaptic dysfunction is an early pathological feature that occurs prior to neurodegeneration and memory dysfunction. Mounting evidence suggests that aggregation of amyloid-${\alpha}$ ($A{\alpha}$) and hyperphosphorylated tau leads to synaptic deficits and neurodegeneration, thereby to memory loss. Among the established genetic risk factors for AD, the ${\varepsilon}4$ allele of apolipoprotein E (APOE) is the strongest genetic risk factor. We and others previously demonstrated that apoE regulates $A{\alpha}$ aggregation and clearance in an isoform-dependent manner. While the effect of apoE on $A{\alpha}$ may explain how apoE isoforms differentially affect AD pathogenesis, there are also other underexplored pathogenic mechanisms. They include differential effects of apoE on cerebral energy metabolism, neuroinflammation, neurovascular function, neurogenesis, and synaptic plasticity. ApoE is a major carrier of cholesterols that are required for neuronal activity and injury repair in the brain. Although there are a few conflicting findings and the underlying mechanism is still unclear, several lines of studies demonstrated that apoE4 leads to synaptic deficits and impairment in long-term potentiation, memory and cognition. In this review, we summarize current understanding of apoE function in the brain, with a particular emphasis on its role in synaptic plasticity and the underlying cellular and molecular mechanisms, involving low-density lipoprotein receptor-related protein 1 (LRP1), syndecan, and LRP8/ApoER2.

• Journal of Veterinary Clinics
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• v.25 no.6
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• pp.458-465
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• 2008

The purpose of this study is to characterize canine mesenchymal stem cells (MSCs) derived from bone marrow (BM) for use in research on the applications of stem cells in canine models of development, physiology, and disease. BM was harvested antemortem by aspiration from the greater tubercle of the humerus of 30 normal beagle dogs. Canine BM-derived MSCs were isolated according to methods developed for other species and were characterized based on their morphology, growth traits, cell-surface antigen profiles, differentiation repertoire, immunocytochemistry results, and neurotrophic factor expression in vitro. The canine MSCs exhibited a fibroblast-like morphology with a polygonal or spindle-shaped appearance and long processes; further, their cell-surface antigen profiles were similar to those of their counterparts in other species such as rodents and humans. The canine MSCs could differentiate into osteocytes and neurons on incubation with appropriate induction media. RT-PCR analysis revealed that these cells expressed NGF, bFGF, SDF-1, and VEGF. This study demonstrated that isolating canine MSCs from BM, stem-cell technology can be applied to a large variety of organ dysfunctions caused by degenerative diseases and injuries in dogs. Furthermore, our results indicated that canine MSCs constitutively secrete endogenous factors that enhance neurogenesis and angiogenesis. Therefore, these cells are potentially useful for treating dogs affected with various neurodegenerative diseases and spinal-cord injuries.

• Biomolecules & Therapeutics
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• v.28 no.1
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• pp.74-82
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• 2020

Alzheimer's disease (AD) is a progressive and most frequently diagnosed neurodegenerative disorder. However, there is still no drug preventing the progress of this disorder. β-Amyrin, an ingredient of the surface wax of tomato fruit and dandelion coffee, is previously reported to ameliorate memory impairment induced by cholinergic dysfunction. Therefore, we tested whether β-amyrin can prevent AD-like pathology. β-Amyrin blocked amyloid β (Aβ)-induced long-term potentiation (LTP) impairment in the hippocampal slices. Moreover, β-amyrin improved Aβ-induced suppression of phosphatidylinositol-3-kinase (PI3K)/Akt signaling. LY294002, a PI3K inhibitor, blocked the effect of β-amyrin on Aβ-induced LTP impairment. In in vivo experiments, we observed that β-amyrin ameliorated object recognition memory deficit in Aβ-injected AD mice model. Moreover, neurogenesis impairments induced by Aβ was improved by β-amyrin treatment. Taken together, β-amyrin might be a good candidate of treatment or supplement for AD patients.

• Molecules and Cells
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• v.37 no.3
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• pp.220-225
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• 2014

Suppression of bone morphogenetic protein (BMP) signaling induces neural induction in the ectoderm of developing embryos. BMP signaling inhibits neural induction via the expression of various neural suppressors. Previous research has demonstrated that the ectopic expression of dominant negative BMP receptors (DNBR) reduces the expression of target genes down-stream of BMP and leads to neural induction. Additionally, gain-of-function experiments have shown that BMP downstream target genes such as MSX1, GATA1b and Vent are involved in the suppression of neural induction. For example, the Vent1/2 genes are involved in the suppression of Geminin and Sox3 expression in the neural ectodermal region of embryos. In this paper, we investigated whether PV.1, a BMP downstream target gene, negatively regulates the expression of FoxD5b, which plays a role in maintaining a neural progenitor population. A promoter assay and a cyclohexamide experiment demonstrated that PV.1 negatively regulates FoxD5b expression.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.522-530
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• 2002

We have already known, neural progenitor cells exist not only in the developing brain, but in certain spots in adult CNS in mammals, so it will be of great value to find out some compounds which can interfere these cells proliferation ability. In this research, we observed that ginsenoside $Rg_1$ can not only enhance neural progenitors' proliferation ability in vitro, but increase neurogenesis in adult mouse dentate gyrus in vivo. Firstly, we set up neural progenitor cells' culture system from embryonic rats' hippocampus and prove their feature through immunocytochemistry. Then by using MTT assay, we found that when growing with ginsenoside $Rg_1(0.5\~2.5{\mu}mol/l)$, the progenitor cells' survival rate nearly doubled, furthermore, we proved that this increase was due to the increment of cell proliferation through $^3H-thimidine$ incorporation assay, hence, we drew the first conclusion: ginsenoside Rg1 has the ability to stimulate neural progenitor cells' proliferation in vitro; in order to observe this compound's effect in vivo, we devised the following experiment: after administering ginsenoside Rg1 (5, 10 mg/kg, once a day) intraperitoneally for two weeks, we examine the number of BrdU positive cells in the dentate gyrus of mice, and found that Rg1 could increase the number of proliferation cells significantly in vivo. From these studies, we are quite sure about Rg1's effects on the proliferation ability of neural progenitor cells both in vitro and in vivo, certain targets of the compound and its underlying mechanisms are in progress.

• Molecules and Cells
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• v.44 no.10
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• pp.723-735
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• 2021

Spemann organizer is a center of dorsal mesoderm and itself retains the mesoderm character, but it has a stimulatory role for neighboring ectoderm cells in becoming neuroectoderm in gastrula embryos. Goosecoid (Gsc) overexpression in ventral region promotes secondary axis formation including neural tissues, but the role of gsc in neural specification could be indirect. We examined the neural inhibitory and stimulatory roles of gsc in the same cell and neighboring cells contexts. In the animal cap explant system, Gsc overexpression inhibited expression of neural specific genes including foxd4l1.1, zic3, ncam, and neurod. Genome-wide chromatin immunoprecipitation sequencing (ChIP-seq) and promoter analysis of early neural genes of foxd4l1.1 and zic3 were performed to show that the neural inhibitory mode of gsc was direct. Site-directed mutagenesis and serially deleted construct studies of foxd4l1.1 promoter revealed that Gsc directly binds within the foxd4l1.1 promoter to repress its expression. Conjugation assay of animal cap explants was also performed to demonstrate an indirect neural stimulatory role for gsc. The genes for secretory molecules, Chordin and Noggin, were up-regulated in gsc injected cells with the neural fate only achieved in gsc uninjected neighboring cells. These experiments suggested that gsc regulates neuroectoderm formation negatively when expressed in the same cell and positively in neighboring cells via soluble factors. One is a direct suppressive circuit of neural genes in gsc expressing mesoderm cells and the other is an indirect stimulatory circuit for neurogenesis in neighboring ectoderm cells via secreted BMP antagonizers.

• Journal of the Korean Applied Science and Technology
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• v.36 no.3
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• pp.876-884
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• 2019

We investigated the effect of moderate- and high-intensity resistance training on hippocampal neurotrophic factors and peripheral CCL11 levels in high-fat diet (HFD)-induced obese mice. C57/black male mice received a 4 weeks diet of normal (control, CON; n = 9) or a high-fat diet (HF; n = 27) to induce obesity. Thereafter, the HF group was subdivided equally into the HF, HF + moderate-intensity exercise (HFME), and HF + high-intensity exercise (HFHE) groups (n = 9, respectively), and mice were subjected to ladder-climbing exercise for 8 weeks. The hippocampal brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels were significantly lower in the HF group than in the CON group (p < 0.05). In addition, in the HFME and HFHE groups were significantly higher than in the HF group (p < 0.05). The peripheral CCL11 levels were significantly higher in the HF group than in the CON group (p < 0.05). In addition, in the HFME and HFHE groups were significantly lower than in the HF group (p < 0.05). However, there was no significant difference according to the exercise intensity among the groups. Collectively, these results suggest that obesity can induce down-regulation of neurotrophic factors and inhibition of neurogenesis. In contrast, regardless of exercise intensity, resistance training may have a positive effect on improving brain function by inducing increased expression of neurotrophic factors.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.399-409
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• 2021

1,2-Diacetylbenzene (DAB) is a metabolite of 1,2-diethylbenzene, which is commonly used in the manufacture of plastics and gasoline. We examined the neurotoxic effects of DAB in young and old rats, particularly its effects on hippocampus. Previously, we reported DAB impairs hippocampal neurogenesis but that the underlying mechanism remained unclear. In this study, we evaluate the toxicities exhibited by DAB in the hippocampi of 6-month-old (young) and 20-month-old (old) male SD rats by treating animals intraperitoneally with DAB at 3 mg/kg/day for 1 week. Hippocampal areas were dissected from brains and RNA was extracted and subjected to RNA-seq analysis. RNA results showed animals exhibited age-dependent sensitivity to the neurotoxic effects of DAB. We observed that inflammatory pathways were up-regulated in old rats but that metabolism- and detoxification-related pathways were up-regulated in young rats. This result in old rats, especially upregulation of the TREM1 signaling pathway (an inflammatory response involved in Alzheimer's disease (AD)) was confirmed by RT-PCR. Our study results provide a better understanding of age-dependent responses to DAB and new insight into the association between DAB and AD.

• Journal of Ginseng Research
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• v.46 no.3
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• pp.408-417
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• 2022

Background: Korean Red Ginseng extract (KRGE) has been used as a health supplement and herbal medicine. Astrocytes are one of the key cells in the central nervous system (CNS) and have bioenergetic potential as they stimulate mitochondrial biogenesis. They play a critical role in connecting the brain vasculature and nerves in the CNS. Methods: Brain samples from KRGE-administered mice were tested using immunohistochemistry. Treatment of human brain astrocytes with KRGE was subjected to assays such as proliferation, cytotoxicity, Mitotracker, ATP production, and O₂ consumption rate as well as western blotting to demonstrate the expression of proteins related to mitochondria functions. The expression of hypoxia-inducible factor-1α (HIF-1α) was diminished utilizing siRNA transfection. Results: Brain samples from KRGE-administered mice harbored an increased number of GFAP-expressing astrocytes. KRGE triggered the proliferation of astrocytes in vitro. Enhanced mitochondrial biogenesis induced by KRGE was detected using Mitotracker staining, ATP production, and O₂ consumption rate assays. The expression of proteins related to mitochondrial electron transport was increased in KRGE-treated astrocytes. These effects were blocked by HIF-1α knockdown. The factors secreted from KRGE-treated astrocytes were determined, revealing the expression of various cytokines and growth factors, especially those related to angiogenesis and neurogenesis. KRGE-treated astrocyte conditioned media enhanced the differentiation of adult neural stem cells into mature neurons, increasing the migration of endothelial cells, and these effects were reduced in the background of HIF-1α knockdown. Conclusion: Our findings suggest that KRGE exhibits prophylactic potential by stimulating astrocyte mitochondrial biogenesis through HIF-1α, resulting in improved neurovascular function.

• Molecules and Cells
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• v.45 no.8
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• pp.588-602
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• 2022

Various RNA-binding proteins (RBPs) are key components in RNA metabolism and contribute to several neurodevelopmental disorders. To date, only a few of such RBPs have been characterized for their roles in neocortex development. Here, we show that the RBP, Rbms1, is required for radial migration, polarization and differentiation of neuronal progenitors to neurons in the neocortex development. Rbms1 expression is highest in the early development in the developing cortex, with its expression gradually diminishing from embryonic day 13.5 (E13.5) to postnatal day 0 (P0). From in utero electroporation (IUE) experiments when Rbms1 levels are knocked down in neuronal progenitors, their transition from multipolar to bipolar state is delayed and this is accompanied by a delay in radial migration of these cells. Reduced Rbms1 levels in vivo also reduces differentiation as evidenced by a decrease in levels of several differentiation markers, meanwhile having no significant effects on proliferation and cell cycle rates of these cells. As an RNA binding protein, we profiled the RNA binders of Rbms1 by a cross-linked-RIP sequencing assay, followed by quantitative real-time polymerase chain reaction verification and showed that Rbms1 binds and stabilizes the mRNA for Efr3a, a signaling adapter protein. We also demonstrate that ectopic Efr3a can recover the cells from the migration defects due to loss of Rbms1, both in vivo and in vitro migration assays with cultured cells. These imply that one of the functions of Rbms1 involves the stabilization of Efr3a RNA message, required for migration and maturation of neuronal progenitors in radial migration in the developing neocortex.