Neuronal differentiation into specific cell types by neurogenic and epigenetic factors

Yunhee Kim 한국발생생물학회 2012 한국발생생물학회 학술발표대회 Vol.31 No.-

Neural precursor cells (NPCs) with abilities to self-renew and differentiate into neurons are born in the subventricular zone of the hippocampus and the subgranular zone in the adult mammalian brain. NPCs maintain their population by symmetric cell division and neuronal cell differentiation started by asymmetric cell division. Asymmetric cell division produces two daughter cells with different cellular fates. It has been shown that multiple transcription factors, like homeodomain transcription factors and basic helix loop helix (bHLH) transcription factors, play cruel role in cell fate determination (Bertrand et al., 2002). Multipotent cortical progenitors are maintained in a proliferative state by bHLH factors including Id and Hes families. The transition from proliferation to neurogenesis involves a coordinate increase in the activity of proneural bHLH factors (Mash1, Neurogenin1, and Neurogenin2). As development proceeds, inhibition of proneural bHLH factors in cortical progenitors promotes the formation of astrocytes. Finally, the formation of oligodendrocytes is triggered by an increase in the activity of bHLH factors Olig1 and Olig2 that may be coupled with a decrease in Id activity. Thus, bHLH factors have key roles in corticogenesis, affecting the timing of differentiation and the specification of cell fate. Hes1 is a vertebrate homologue of the Drosophila bHLH protein Hairy, originally known as a transcriptional repressor that negatively regulates neuronal differentiation. Hes1 expression in neuronal precursors precedes and represses the expression of the neuronal commitment gene Mash1, a bHLH activator homologus to the proneuronal Achaete-Scute genes in Drosophila (Campuzano and Modolell, 1992). Down regulation of Hes1 expression in developing neuroblasts may be necessary for the induction of a regulatory cascade of bHLH activator proteins that controls the commitment and progression of neural differentiation. Expression of Hes1 inhibited neurite outgrowth, whereas Mash1 expression increased neurite outgrowth. Mash1 can induce bipolar neuron differentiation (Tomita et al., 1996) and NSCs culture obtained from Mash1-/- mice cannot differentiate into GBAergic neurons (Oishi et al., 2009) Hes1 is an essential effector for Notch signaling, which regulates the maintenance of undifferentiated cells (Artavanis-Tsakonas et al., 1999). In contrast, it is previously reported that platelet-derived growth factor induces the expression of Mash1 mRNA by regulating the phosphorylation of Hes1 and TLE1 (Ju et al., 2004). Hes1 is required for neuronal differentiation in PDGF treated NSC cultures. The major cell types in the cerebral cortex and hippocampus are the glutamatergic neurons and the GABAergic neurons. Cholinergic neurons are important in spatial learning and memory formation and depleted in patient’s brain of early Alzheimer’s disease. It has not been clear, however, whether new born adult NPCs could generate different cell types of neurons with distinct cellular and physiological properties. During the development, glutamatergic neurons consisting of radially migrating neurons are originated from the ventricular zone of the dorsal telenchephalon (pallium) and give rise to pyramidal neurons. Glutamate and glutamate receptors are involved in cognitive functions by forming major excitatory network. GABAergic neurons in the neocortex and hippocampus are in part migrated from the ventral telenchephalon or from the dorsal NPCs and function as local interneurons by forming inhibitory networks which regulate large populations of glutamatergic pyramidal neurons. During the development, spatiotemporal gene expression regulated by extracellular signaling factors is believed to determine the formation of neuronal phenotypes. Platelet derived growth factor B is known to induce the differentiation into neurons rather than glial cells in the rat NPCs. We found that platelet derived growth factor B is expressed in dorsal cortex and hippocampus more than in ventral cortex in the period of pyramidal cell differentiation of the embryonic rat brain. It indeed induces cell type specific differentiation into glutamatergic cells that produce the glutamate transpoter, vGluT1 and glutamate at the late stage of differentiation although it promotes neuronal differentiation at the early stage in NPCs primarily cultured from the rat embryonic hippocampus. Brain-derived neurotrophic factor, however, facilitated GABAergic differentiation in the hippocampal NPCs that generate glutamatergic pyramidal cells in a similar manner. We also found many transcriptional factors such as homeobox genes (Dlx1, Nkx2.1, Pax6) and bHLH genes (NeuroD, Ngn1, Hes1) are involved in cell type specific differentiation into glutamatergic, GABAergic, and cholinergic cells. We observed the expression of Pax6, homeodomain transcription factor, and Hes1, bHLH transcription factor, increased during PDGF-induced early differentiation in neural stem cells. These transcription factors, however, are also expressed in differentiated neurons with specific phenotype at late differentiation stage. We found pax6 is expressed in cholinergic neurons in the adult brains and in cultures. Phosphorylation of neurogenic transcription factors by protein kinases has been reported as predominant strategy in gene regulation during neuronal development and these regulated activities of different transcription factors are known to be involved in cell fate determination. Homeodomaininteracting protein kinases2 (HIPK2) which belongs to HIPK family has been identified as a nuclear serine-threonine kinase and is known to interact with several transcription factors to regulate gene transcriptions. Among several transcription factors, HIPK2 is mainly reported to target the homeodomain transcription factors such as Nkx and Pax6. Considering the importance of homeodomain transcription factors in neurogenesis and differentiation, HIPK2 also seem to play critical roles in those transcriptional regulations during embryogenesis. To define the roles of HIPK2 in neuronal differentiation during embryonic development, we investigated the expression patterns of neurogenic transcription factors such as Pax6, Hes1 and Mash1 in HIPK2 overexpressing NSCs. Hes1 showed different expression patterns between the wild type and mutant HIPK2 overexpressed cells and Mash1, which is reported to be repressed by Hes1, also showed altered expression patterns. We detected the mRNA expression of Hes1 is upregulated by HIPK2 during neuronal differentiation. The overexpressed Pax6 induced differentiation of neural stem cells into cholinergic neurons and suppressed differentiation into GABAnergic neuron both in vitro and in vivo transplantation study. To evaluate the effect of Pax6 on the transcriptional activation of Hes1 promoter, we performed luciferase reporter assay in NIH3T3 cells. Reporter expression of Hes1 promoter was enhanced upon stimulation with wild type Pax6 and wild type HIPK2. Furthermore, the HDAC inhibition mediated by TSA(Trichostatin A) has been shown to repress the reporter expression. The treatment of TSA increased neurofilaments and GAD expression in E14.5 cortical neuronal cell. These findings suggest that Pax6 promotes neuronal subtype differentiation via regulation of Hes1 bHLH transcription factor, which is mediated by HDAC. To examine the effect of Pax6 and HIPK2 on the transcriptional activation of Hes1, efficiency of hes1 promoter was measured by a luciferase reporter assay. When DNA constructs encoding Pax6 and HIPK2 were transfected along with Hes1 promoter, the expression of the reporter was highly increased. Furthermore, the HDAC inhibition mediated by TSA(Trichostatin A) repressed the reporter expression. Interaction of Pax6 and HIPK2 was shown by co-immunoprecipitation and binding of Pax6 to hes1 promoter was detected by chromatin immunoprecipitation. I also found overexpression of HIPK2 and Pax6 facilitated neural stem cells to differentiate into cholinergic cell fate in NSCs primarily cultured from the rat hippocampus. This is also supported by analysis of the brains of sey/neu Pax6 mutant mice and HIPK2 knock out mice. These findings suggest that Pax6 activation by HIPK2 promotes neuronal subtype differentiation via up regulation of Hes1 and down regulation of Mash1 and it is mediated by HDAC.

Influencing Factors on COVID-19 Preventive Behavior in College students : An Ecological Perspective

Yunhee Kim,Hyeseung Kim 한국간호과학회 2021 한국간호과학회 학술대회 Vol.2021 No.10

Aim(s): The purpose of this study is to identify the factors affecting to the COVID-19 preventive behavior in college students based on ecological perspectives, and provide basic data for the development of preventive programs to improve COVID-19 preventive behavior. Method(s): The study recruited a total of 221 college students, through an online survey through three online communities which are mostly used by college students. The data were collected from July 24 to August 9, 2021. The collected data were analyzed using the descriptive statistics, independent t-test, one-way ANOVA, Pearson’s correlation coefficient, and hierarchical multiple regression using SPSS 25.0 version program. Result(s): There was a statistically significant difference in COVID-19 preventive behavior depending on their age(t=3.06, p=.003) and their experience in self quarantined(t=3.53, p=.028) among the general characteristics of the subjects. COVID-19 preventive behavior showed a statistically significant positive correlation with perceived susceptibility(r=.525, p<.001), perceived severity(r=.481, p<.001), perceived benefits(r=.526, p<.001), subjective norms(r=.608, p<.001), and sense of community(r=.302, p<.001). In addition, perceived barriers was found to have a statistically significant negative correlation with COVID-19 preventive behavior(r=-.172, p=0.010). In hierarchical multiple regression, all of 3 models were examined by intrapersonal, interpersonal, and organizational factors in ecological model. As a result, perceived susceptibility(β=.208, p=.003), perceived benefits(β=.178, p=.007), subjective norms(β=.309, p<.001) were found to have a significant association with the COVID-19 preventive behaviors of college students. These variables explained the 44.6% variance in COVID-19 preventive behavior of college students(F=23.18, p<.001). Conclusion(s): COVID-19 preventive behavior of college students were associated with perceived susceptibility, perceived benefits, and subjective norms. Based on the results of this study, it is expected to develop a COVID-19 preventive program to improve the COVID-19 preventive behavior of college students.

A Pilot Study Evaluating the Effectiveness of System-Wide Positive Behavior Support for Institutionalized Orphans in South Korea

Yunhee Kim,Youngsun Park 대한신경정신의학회 2020 PSYCHIATRY INVESTIGATION Vol.17 No.12

Objective In South Korea, the placement of orphans in institutions is still common, despite evidence of its adverse influence on children’s psychological, emotional, physical, and cognitive development. In this preliminary study, we evaluate whether system-wide positive behavior support (SWPBS) is effective for decreasing externalizing problems in institutionalized children. Methods SWPBS was provided for one month to 36 school-aged boys who had lived in an orphanage for an average of 8.72 years (SD=2.52), along with their 10 caregivers. Direct observation of the frequency of target behaviors in the participating children, caregivers’ ratings of the severity of children’s problematic behaviors, self-reported caregiving stress (i.e., Parenting Stress Scale), and intervention fidelity were dependent variables. Results After receiving SWPBS, the frequency of problematic behaviors in the participating children showed a mean decrease of 73.6%. The caregivers also reported seeing a decrease in the severity of their children’s problematic behaviors after SWPBS compared to before. Conclusion SWPBS may be a promising intervention to decrease externalizing behaviors in school-aged children who have been living in institutions for a long time and have shown mental health issues.

Enhancing Signal Amplification of Hybrid Inputs in Riboswitch-based Systems Using Modular and Titratable Toehold Switches

Yunhee HWANG,Seong Gyeong KIM,Sungho Jang JANG,Jongmin Kim KIM,Gyoo Yeol JUNG 한국생물공학회 2023 한국생물공학회 학술대회 Vol.2023 No.4

Latent Tuberculosis Infection Screening and Treatment in Congregate Settings (TB FREE COREA): Demographic Profiles of Interferon-Gamma Release Assay Cohort

Kim Hyung Woo,Min Jinsoo,Choi Joon Young,Shin Ah Young,Myong Jun-Pyo,Lee Yunhee,Yim Hyeon Woo,Jeong Hyunsuk,Bae Sanghyuk,Shim Eunhye,In Hyekyung,Chun Chaemin,Kim Gahee,Kang Ji Young,Lee Sung-Soon,Park 대한의학회 2021 Journal of Korean medical science Vol.36 No.36

In 2017, the Korean government launched an unprecedentedly large-scaled latent tuberculosis infection (LTBI) screening project which covered more than a million individuals in congregate settings. A total of 1,047,689 participants of source population (n = 2,336,157) underwent LTBI testing from 2017 to 2018. The overall LTBI test uptake rate during this project was 44.8%. Workers in daycare centers (83.5%) and kindergartens (78.9%) showed high participation rate. A total of 1,012,206 individuals with valid results of interferongamma release assay (IGRA) were selected to constitute the IGRA cohort. Most of the enrolled participants in the IGRA cohort were in their working age. Approximately, threequarters of total enrolled population were female. Investigating the LTBI prevalence, stages of LTBI care cascade, natural history of LTBI, efficacy of LTBI treatment and cost-effectiveness of LTBI screening are feasible within this IGRA cohort.

09. Joint Attention and Language Development in Infants: A Meta-Analysis

( Yunhee Kim ),( Juyoung Lee ),( Heekyung Chun ) 한국유아교육학회 2019 정기학술대회 논문집 Vol.2019 No.2

Color moiré pattern simulation and analysis in three-dimensional integral imaging for finding the moiré-reduced tilted angle of a lens array

Kim, Yunhee,Park, Gilbae,Jung, Jae-Hyun,Kim, Joohwan,Lee, Byoungho The Optical Society 2009 Applied optics Vol.48 No.11

<P>We propose a color moiré pattern simulation and analysis method in integral imaging for finding the moiré-reducing tilted angle of a lens array. According to the tilted angle, the color moiré patterns are simulated on the assumption of ray optics. The spatial frequencies of the color moiré patterns are numerically analyzed using a spatial Fourier transform for finding the optimal angle where the moiré is reduced. With the proposed technique the visualization of the color moiré pattern and its analysis are enabled. The moiré-reduced three-dimensional images can be displayed. The principle of the proposed method, simulation results, and their analysis are provided. Experimental results verify the validity of the proposed method.</P>

Comparison of Efficacy and Safety Between Propranolol and Steroid for Infantile Hemangioma : A Randomized Clinical Trial

Kim, Kyu Han,Choi, Tae Hyun,Choi, Yunhee,Park, Young Woon,Hong, Ki Yong,Kim, Dong Young,Choe, Yun Seon,Lee, Hyunjung,Cheon, Jung-Eun,Park, Jung-Bin,Park, Kyung Duk,Kang, Hyoung Jin,Shin, Hee Young,Jeo American Medical Association 2017 JAMA dermatology Vol.153 No.6

Treatment with hydroxyurea and tyrphostin-1 significantly improves the transduction efficiency of recombinant adeno-associated viruses in human cancer cells.

Kim, Sung Jin,Nam, Young Ran,Shin, Ohkyu,Choi, Jene,Lee, Boyoung,Chang, Jin Woo,Kwon, Yunhee Kim,Park, Keerang,Lee, Heuiran National Hellenic Research Foundation 2005 ONCOLOGY REPORTS Vol.14 No.6

<P>To enhance the transduction efficiency (TE) of a recombinant adeno-associated virus 2 (rAAV2) in human cancer cells, we examined the combined effects of various chemicals known to influence the rAAV2 transduction process at distinct steps. Among the agents tested were trichostatin A, a histone deacetylase inhibitor, MG-132, a proteosome inhibitor, the genotoxic agents hydroxyurea, aphidicolin, etoposide and camptothecin, and tyrphostin-1, an epidermal growth factor receptor inhibitor. During or after chemical treatment, various human cancer cells were infected with rAAV2 expressing beta-galactosidase. Treatment with hydroxy-urea or etoposide plus tyrphostin-1 dramatically increased the TE in most cell lines. The combination of hydroxyurea plus tyrphostin-1 increased TE to 37.7+/-7.9%, 32.8+/-2.0% and 31.8+/-2.1% in SK-Hep1, HeLa, and HCT116 cells, respectively. In addition, following rAAV2 infection and treatment with hydroxyurea plus tyrphostin-1, long-term transgene expression was observed for up to 6 months, with no damage to the transduced cells. These results indicate that rAAV2 transgene expression can be significantly enhanced by a combination of chemical agents with distinct activity and prolonged gene expression can occur following rAAV2 gene transfer into human cancer cells.</P>

Development of Signal Amplified Riboswitch-based Coenzyme B12 Sensor by Toehold Switches Modulator

Yunhee HWANG,Seong Gyeong KIM,Sungho JANG,Jongmin KIM,Gyoo Yeol JUNG 한국생물공학회 2022 한국생물공학회 학술대회 Vol.2022 No.4