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Nuclear UPF1 Is Associated with Chromatin for Transcription-Coupled RNA Surveillance
Hong, Dawon,Park, Taeyoung,Jeong, Sunjoo Korean Society for Molecular and Cellular Biology 2019 Molecules and cells Vol.42 No.7
mRNA quality is controlled by multiple RNA surveillance machineries to reduce errors during gene expression processes in eukaryotic cells. Nonsense-mediated mRNA decay (NMD) is a well-characterized mechanism that degrades error-containing transcripts during translation. The ATP-dependent RNA helicase up-frameshift 1 (UPF1) is a key player in NMD that is mostly prevalent in the cytoplasm. However, recent studies on UPF1-RNA interaction suggest more comprehensive roles of UPF1 on diverse forms of target transcripts. Here we used subcellular fractionation and immunofluorescence to understand such complex functions of UPF1. We demonstrated that UPF1 can be localized to the nucleus and predominantly associated with the chromatin. Moreover, we showed that UPF1 associates more strongly with the chromatin when the transcription elongation and translation inhibitors were used. These findings suggest a novel role of UPF1 in transcription elongation-coupled RNA machinery in the chromatin, as well as in translation-coupled NMD in the cytoplasm. Thus, we propose that cytoplasmic UPF1-centric RNA surveillance mechanism could be extended further up to the chromatin-associated UPF1 and co-transcriptional RNA surveillance. Our findings could provide the mechanistic insights on extensive regulatory roles of UPF1 for many cellular RNAs.
Modulation of Muscarinic K+ Channel by Protein Kinase C in Ischemic Rat Atrial Myocytes
Kang, Dawon,Lee, Hong Sik,Hong, Seong Geun,Han, Jaehee 대한심장학회 2005 Korean Circulation Journal Vol.35 No.11
BACKGROUND AND OBJECTIVES: Recent studies have shown that many kinds of K+ channels, including the muscarinic K+ channel (KACh), are activated in the ischemic heart. It is known that these channels can be modulated by phosphorylation. However, little is known about the function of the KACh in ischemic hearts. In this study, we examined whether the KACh channel is mediated by protein kinase C (PKC) activation in rat atrial myocytes under ischemic conditions. MATERIALS AND METHODS: Single atrial cells of adult rat heart were prepared by collagenase digestion. Channel activity of KACh was recorded by cell-attached configuration from single atrial cells under ischemic conditions, using a patch clamp technique. To simulate ischemia, adenosine or potassium cyanide (KCN) was applied to atrial myocytes, and Western blot was performed to specify PKC isoforms. RESULTS: Adenosine and KCN markedly increased KACh channel activity. The responses to adenosine and KCN were increased 3-fold at mean open time from that observed with control. Channel activity of KACh was blocked by pretreatment with PKC antagonists such as sphingosine, Go 6976, and rottlerin. PKC alpha and PKC betaI isoform levels were increased in the membrane fraction of ischemic heart, indicating that ischemic stress might trigger translocation of cytosolic PKC to the cell membrane. CONCLUSION: These results show that KACh channels are modulated by PKC activation under ischemic conditions induced by adenosine or KCN. Therefore, the channels can protect the heart from ischemic stress by increasing channel activity.
Robotic transoral thyroidectomy for papillary thyroid carcinoma
Hong Kyu Kim,Dawon Park,Hoon Yub Kim 대한외과학회 2019 Annals of Surgical Treatment and Research(ASRT) Vol.96 No.5
Transoral robotic thyroidectomy (TORT) is well consistent with the primary goal of remote-access thyroid surgery, which is to avoid a visible cervical scar. Additionally, the extent of transoral thyroidectomy dissection is less than that of other remote-access surgical procedures. Owing to these merits of the transoral approach, several institutions around the world are now performing this procedure. Since transoral thyroidectomy is performed in a confined, narrow space, and is characterized by a close distance from the ports to the working space, more benefits can be derived from multiarticulation of robotic instruments. Especially when performing left lobectomy by TORT, the surgeon can use right-handed robotic instruments over the thyroid cartilage with the merits of multiarticulation. In this study, we present our unique procedure of left lobectomy by TORT in detail.
Transoral Robotic Thyroidectomy
( Dawon Park ),( Hong Kyu Kim ),( Hoon Yub Kim ) 대한갑상선학회 2018 International Journal of Thyroidology Vol.11 No.1
Transoral approach for thyroidectomy recently gains a lot of attention among the thyroid surgeons, with definite merits over previously developed remote-access approaches. The approach not only resulted in the ideal cosmetic outcome but less postoperative pain with smaller dissection plane in comparison with other approaches. We have successfully introduced the robotic surgical system and its related techniques to this transoral surgical approach for thyroidectomy, which enables the surgeon to have the three-dimentional operative vision and to use the articulating instruments to enhance th eoptimal surgical outcomes. Herein, our unique procedures of transoral robotic thyroidectomy (TORT) are described, and possible advantages and disadvantages of the operation are discussed.
Kang, Dawon,Kim, Sung-Hee,Hwang, Eun-Mi,Kwon, Oh-Sang,Yang, Hae-Young,Kim, Eun-Sook,Choi, Tae Hyun,Park, Jae-Yong,Hong, Seong-Geun,Han, Jaehee Blackwell Publishing Ltd 2007 Experimental dermatology Vol.16 No.12
<P>Abstract: </P><P>Recent studies have shown that keratinocytes can sense temperature via thermo-transient receptor potential (TRP) channels. It is not known whether other thermosensitive ion channels such as TREK-1, TREK-2 and TRAAK (TREKs/TRAAK) that are members of the two-pore domain K<SUP>+</SUP> (K<SUB>2P</SUB>) channel family are expressed in human keratinocytes. Here, we identified the expression of TREKs/TRAAK in human keratinocytes-derived cell line HaCaT cells using RT-PCR, immunocytochemistry, Western blot analysis and patch-clamp technique. RT-PCR showed that all six K<SUB>2P</SUB> channels tested (TASK-1, TASK-3, TREK-1, TREK-2, TRAAK and TASK-2) were expressed in HaCaT cells, as well as in skin and dorsal root ganglion (DRG) of rat. The expression of TREKs/TRAAK mRNA identified by RT-PCR was further studied at the protein level. Using anti-TREK-1, -TREK-2 and -TRAAK, bands of ∼46, ∼60 and ∼43 kDa, respectively, were observed at plasma membrane of HaCaT cells. Immunostaining also showed that TREK-1, TREK-2 and TRAAK were expressed in all area of cells including plasma membrane. Whole-cell K<SUP>+</SUP> currents recorded from HaCaT cells were activated by arachidonic acid and heat. These results suggest that TREKs/TRAAK channels could act as thermosensors in human keratinocytes.</P>
박다원,최영준,홍정욱,Park, Dawon,Choi, Youngjun,Hong, Jung-Wuk 한국지진공학회 2021 한국지진공학회논문집 Vol.25 No.3
A shear wall is a structural member designed to effectively resist in-plane lateral forces, such as strong winds and earthquakes. Due to its efficiency and stability, shear walls are often installed in residential buildings and essential facilities such as nuclear power plants. In this research, to predict the results of the shaking table test of the three-story shear wall RC structure hosted by the Korea Atomic Energy Research Institute, three types of numerical modeling techniques are proposed: Preliminary, Calibrated 1, and Calibrated 2 models, in order of improvement. For the proposed models, an earthquake of the 2016 Gyeongju, South Korea (peak ground acceleration of 0.28 g) and its amplified earthquake (peak ground acceleration of 0.50 g) are input. The response spectra of the measuring points are obtained by numerical analysis. Good agreement is observed in the comparisons between the experiment results and the simulation conducted on the finally adopted numerical model, Calibrated 2. In the process of improving the model, this paper investigates the influences of the mode shape, material properties, and boundary conditions on the structure's seismic behavior.