CNTF에 의한 신경세포의 재생에 관여하는 신호전달체계에 관한 연구

은수용,조철만,이지연,박정욱,강병학,엄의영,안상미 국립보건연구원 1998 국립보건원보 Vol.35 No.-

Cell type-specific upregulation of myristoylated alanine-rich C kinase substrate and protein kinase C-α, -β I, -β II, and -δ in microglia following kainic acid-induced seizures

은수용,김은혜,강기석,김화정,안상미,김순종,조수현,김상정,Perry J. Blackshear,김준 생화학분자생물학회 2006 Experimental and molecular medicine Vol.38 No.3

Myristoylated alanine-rich C kinase substrate (MARCKS) is a (PKC) substrate and has been implicated in actin cytoskeletal rearrangement in response to extra-cellular stimuli. Although MARCKS was extensively examined in various cell culture systems, the physiological function of MARCKS in the central nervous system has not been clearly understood. We investigated alterations of cellular distribution and phosphorylation of MARCKS in the hippocampus following kainic acid (KA)-induced seizures. KA (25 mg/kg, i.p.) was administered to eight to nine week-old C57BL/6 mice. Behavioral seizure activity was observed for 2 h after the onset of seizures and was terminated with diazepam (8 mg/kg, i.p.). The animals were sacrificed and analyzed at various points in time after the initiation of seizure activity. Using double-labeling immunofluorescence analy-phosphorylation of MARCKS was dramatically upregulated specifically in microglial cells after KA-induced seizures, but not in other types of glial cells. PKC α, β I, β II and δ, from various PKC isoforms examined, also were markedly upregulated, speci-fically in microglial cells. Moreover, immunore-activities of phosphorylated MARCKS were co- localized in the activated microglia with those of the above isoforms of PKC. Taken together, our in vivo data suggest that MARCKS is closely linked to microglial activation processes, which are important mation and neurodegeneration.

A Helix-induced Oligomeric Transition of Gaegurin 4, an Antimicrobial Peptide Isolated from a Korean Frog

은수용,김순종,장혜경,한성규,류판동,이병재,한규훈 한국분자세포생물학회 2006 Molecules and cells Vol.21 No.2

Sustained K+ Outward Currents are Sensitive to Intracellular Heteropodatoxin2 in CA1 Neurons of Organotypic Cultured Hippocampi of Rats

정성철,은수용 대한약리학회 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.5

Blocking or regulating K+ channels is important for investigating neuronal functions in mammalian brains, because voltage-dependent K+ channels (Kv channels) play roles to regulate membrane excitabilities for synaptic and somatic processings in neurons. Although a number of toxins and chemicals are useful to change gating properties of Kv channels, specific effects of each toxin on a particular Kv subunit have not been sufficiently demonstrated in neurons yet. In this study, we tested electrophysiologically if heteropodatoxin2 (HpTX2), known as one of Kv4-specific toxins, might be effective on various K+ outward currents in CA1 neurons of organotypic hippocampal slices of rats. Using a nucleated-patch technique and a pre-pulse protocol in voltage-clamp mode, total K+ outward currents recorded in the soma of CA1 neurons were separated into two components, transient and sustained currents. The extracellular application of HpTX2 weakly but significantly reduced transient currents. However, when HpTX2 was added to internal solution, the significant reduction of amplitudes were observed in sustained currents but not in transient currents. This indicates the non-specificity of HpTX2 effects on Kv4 family. Compared with the effect of cytosolic 4-AP to block transient currents, it is possible that cytosolic HpTX2 is pharmacologically specific to sustained currents in CA1 neurons. These results suggest that distinctive actions of HpTX2 inside and outside of neurons are very efficient to selectively reduce specific K+ outward currents.

Expression of Fibroblast Growth Factor Receptor 3 in the Recurrence of Non-Muscle-Invasive Urothelial Carcinoma of the Bladder

맹영희,은수용,허정식 대한비뇨의학회 2010 Investigative and Clinical Urology Vol.51 No.2

Purpose: The fibroblast growth factor receptor 3 (FGFR3) gene is known to be frequently mutated in noninvasive urothelial carcinomas of the bladder. In this study, we investigated the expression of FGFR3, Ki-67, and p53 in bladder cancers and the effects of expression on tumor recurrence. Materials and Methods: Fifty-five cases of primary bladder cancer were examined by immunohistochemistry. The relationship of these markers with various clinicopathological factors, including recurrence, was assessed. Results: Positivity for cytoplasmic FGFR3 (FGFR3-c) was associated with a lower cancer grade (p=0.022) and stage (p=0.011). Recurrence was more frequent in patients with a higher stage, negative FGFR3-c, and high Ki-67 expression. According to univariate analysis, predictors of recurrence-free survival included the following: age, stage, FGFR-c, Ki-67, and p53. However, none of these was independent from the other parameters in multivariate studies. Conclusions: The immunohistochemical expression of FGFR3 is not only one of the characteristic features of lower-grade and lower-stage urothelial carcinoma but also a possible marker in predicting disease recurrence. Purpose: The fibroblast growth factor receptor 3 (FGFR3) gene is known to be frequently mutated in noninvasive urothelial carcinomas of the bladder. In this study, we investigated the expression of FGFR3, Ki-67, and p53 in bladder cancers and the effects of expression on tumor recurrence. Materials and Methods: Fifty-five cases of primary bladder cancer were examined by immunohistochemistry. The relationship of these markers with various clinicopathological factors, including recurrence, was assessed. Results: Positivity for cytoplasmic FGFR3 (FGFR3-c) was associated with a lower cancer grade (p=0.022) and stage (p=0.011). Recurrence was more frequent in patients with a higher stage, negative FGFR3-c, and high Ki-67 expression. According to univariate analysis, predictors of recurrence-free survival included the following: age, stage, FGFR-c, Ki-67, and p53. However, none of these was independent from the other parameters in multivariate studies. Conclusions: The immunohistochemical expression of FGFR3 is not only one of the characteristic features of lower-grade and lower-stage urothelial carcinoma but also a possible marker in predicting disease recurrence.

Analytical ultracentrifugation for characterizing nanoparticles and their bioconjugates

김순종,이희정,은수용 한국공업화학회 2008 한국공업화학회 연구논문 초록집 Vol.2008 No.1

Long-term Synaptic Plasticity: Circuit Perturbation and Stabilization

박주민,정성철,은수용 대한약리학회 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.6

At central synapses, activity-dependent synaptic plasticity has a crucial role in information processing,storage, learning, and memory under both physiological and pathological conditions. Onewidely accepted model of learning mechanism and information processing in the brain is HebbianPlasticity: long-term potentiation (LTP) and long-term depression (LTD). LTP and LTD are respectivelyactivity-dependent enhancement and reduction in the efficacy of the synapses, which are rapid andsynapse-specific processes. A number of recent studies have a strong focal point on the criticalimportance of another distinct form of synaptic plasticity, non-Hebbian plasticity. Non-Hebbianplasticity dynamically adjusts synaptic strength to maintain stability. This process may be very slowand occur cell-widely. By putting them all together, this mini review defines an important conceptualdifference between Hebbian and non-Hebbian plasticity.

미토콘드리아 기능을 통해 내인성 글루탐산이 신경세포 생존에 미치는 영향

노진우,김혜지,은수용,강문석,정성철,양윤실,Noh, Jin-Woo,Kim, Hye-Ji,Eun, Su-Yong,Kang, Moon-Suk,Jung, Sung-Cherl,Yang, Yoon-Sil 제주대학교 의과학연구소 2018 The Journal of Medicine and Life Science Vol.15 No.2

Neuronal excitotoxicity induces mitochondrial dysfunction and the release of proapoptotic proteins. Excitotoxicity, the process by which the overactivation of excitatory neurotransmitter receptors leads to neuronal cell death. Neuronal death by excitotoxicity was related to neuronal degenerative disorders and hypoxia, results from excessive exposure to excitatory neurotransmitters, such as glutamate. Glutamate acts at NMDA receptors in cultured neurons to increase the intracellular free calcium concentration. Therefore endogenous glutamate may be a key factor to regulate neuronal cell death via activating $Ca^{2+}$ signaling. For this issue, we tested some conditions to alter intracellular $Ca^{2+}$ level in dissociated hippocampal neurons of rats. Cultured hippocampal neuron were treated by KCl (20 mM), $CaCl_2$ (3.8 mM) and glutamate ($5{\mu}M$) for 24 hrs. Interestingly, The Optical Density of hippocampal neurons was increased by high KCl application in MTT assay data. This enhanced response by high KCl was dependent on synaptic $Ca^{2+}$ influx but not on intracellular $Ca^{2+}$ level. However, the number of neurons seemed to be not changed in Hoechst 33342 staining data. These results suggest that enhancement of synaptic activity plays a key role to increase mitochondrial signaling in hippocampal neurons.

The Downregulation of Somatic A-Type K+ Channels Requires the Activation of Synaptic NMDA Receptors in Young Hippocampal Neurons of Rats

강문석,양윤실,김선희,박주민,은수용,정성철 대한약리학회 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.2

The downregulation of A-type K+ channels (IA channels) accompanying enhanced somatic excitabilitycan mediate epileptogenic conditions in mammalian central nervous system. As IA channels are dominantlytargeted by dendritic and postsynaptic processings during synaptic plasticity, it is presumablethat they may act as cellular linkers between synaptic responses and somatic processings under variousexcitable conditions. In the present study, we electrophysiologically tested if the downregulation ofsomatic IA channels was sensitive to synaptic activities in young hippocampal neurons. In primarilycultured hippocampal neurons (DIV 6~9), the peak of IA recorded by a whole-cell patch was significantlyreduced by high KCl or exogenous glutamate treatment to enhance synaptic activities. However, thepretreatment of MK801 to block synaptic NMDA receptors abolished the glutamate-induced reductionof the IA peak, indicating the necessity of synaptic activation for the reduction of somatic IA. Thiswas again confirmed by glycine treatment, showing a significant reduction of the somatic IA peak. Additionally, the gating property of IA channels was also sensitive to the activation of synaptic NMDAreceptors, showing the hyperpolarizing shift in inactivation kinetics. These results suggest thatsynaptic LTP possibly potentiates somatic excitability via downregulating IA channels in expressionand gating kinetics. The consequential changes of somatic excitability following the activity-dependentmodulation of synaptic responses may be a series of processings for neuronal functions to determineoutputs in memory mechanisms or pathogenic conditions.

Chronic Ca2+ influx through voltage-dependent Ca2+ channels enhance delayed rectifier K+ currents via activating Src family tyrosine kinase in rat hippocampal neurons

양윤실,전상찬,김동관,은수용,정성철 대한약리학회 2017 The Korean Journal of Physiology & Pharmacology Vol.21 No.2

Excessive influx and the subsequent rapid cytosolic elevation of Ca2+ in neurons is the major cause to induce hyperexcitability and irreversible cell damage although it is an essential ion for cellular signalings. Therefore, most neurons exhibit several cellular mechanisms to homeostatically regulate cytosolic Ca2+ level in normal as well as pathological conditions. Delayed rectifier K+ channels (IDR channels) play a role to suppress membrane excitability by inducing K+ outflow in various conditions, indicating their potential role in preventing pathogenic conditions and cell damage under Ca2+-mediated excitotoxic conditions. In the present study, we electrophysiologically evaluated the response of IDR channels to hyperexcitable conditions induced by high Ca2+ pretreatment (3.6 mM, for 24 hours) in cultured hippocampal neurons. In results, high Ca2+-treatment significantly increased the amplitude of IDR without changes of gating kinetics. Nimodipine but not APV blocked Ca2+-induced IDR enhancement, confirming that the change of IDR might be targeted by Ca2+ influx through voltage-dependent Ca2+ channels (VDCCs) rather than NMDA receptors (NMDARs). The VDCC-mediated IDR enhancement was not affected by either Ca2+-induced Ca2+ release (CICR) or small conductance Ca2+-activated K+ channels (SK channels). Furthermore, PP2 but not H89 completely abolished IDR enhancement under high Ca2+ condition, indicating that the activation of Src family tyrosine kinases (SFKs) is required for Ca2+-mediated IDR enhancement. Thus, SFKs may be sensitive to excessive Ca2+ influx through VDCCs and enhance IDR to activate a neuroprotective mechanism against Ca2+-mediated hyperexcitability in neurons.