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Choline dehydrogenase interacts with SQSTM1/p62 to recruit LC3 and stimulate mitophagy.
Park, Sungwoo,Choi, Seon-Guk,Yoo, Seung-Min,Son, Jin H,Jung, Yong-Keun Landes Bioscience 2014 AUTOPHAGY Vol.10 No.11
<P>CHDH (choline dehydrogenase) is an enzyme catalyzing the dehydrogenation of choline to betaine aldehyde in mitochondria. Apart from this well-known activity, we report here a pivotal role of CHDH in mitophagy. Knockdown of CHDH expression impairs CCCP-induced mitophagy and PARK2/parkin-mediated clearance of mitochondria in mammalian cells, including HeLa cells and SN4741 dopaminergic neuronal cells. Conversely, overexpression of CHDH accelerates PARK2-mediated mitophagy. CHDH is found on both the outer and inner membranes of mitochondria in resting cells. Interestingly, upon induction of mitophagy, CHDH accumulates on the outer membrane in a mitochondrial potential-dependent manner. We found that CHDH is not a substrate of PARK2 but interacts with SQSTM1 independently of PARK2 to recruit SQSTM1 into depolarized mitochondria. The FB1 domain of CHDH is exposed to the cytosol and is required for the interaction with SQSTM1, and overexpression of the FB1 domain only in cytosol reduces CCCP-induced mitochondrial degradation via competitive interaction with SQSTM1. In addition, CHDH, but not the CHDH FB1 deletion mutant, forms a ternary protein complex with SQSTM1 and MAP1LC3 (LC3), leading to loading of LC3 onto the damaged mitochondria via SQSTM1. Further, CHDH is crucial to the mitophagy induced by MPP+ in SN4741 cells. Overall, our results suggest that CHDH is required for PARK2-mediated mitophagy for the recruitment of SQSTM1 and LC3 onto the mitochondria for cargo recognition.</P>
Wontae Kim,Sungwoo Bae,Haecheol Park,Kwanho Park,Sang beom Lee,Gilsang Jeong,Youngcheol Choi,Youngho Koh 한국응용곤충학회 2010 한국응용곤충학회 학술대회논문집 Vol.2010 No.05
The black soldier fly (BSF), Hermetia illucens, is known as a beneficial insect and feeds on organic materials derived from animals and human, resulting in reduction of food waste and conversion of organic materials. Despite of a lot of study about the BSF, there is a less information about composition of digestive enzyme of the BSF larva. Experimentally, there is no evidence about characterization of digestive enzyme of the BSF. We investigated biochemical property of digestive enzyme released from the salivary and gut of the BSF. Through digestive enzyme assay, we found that the BSF has amylase, lipase and protease activity in gut extracts, resulting in that the BSF belong to polyphagous insect group. In the BSF gut, trypsin-like protease activity showed one peak at various temperature and pH condition. This result means the BSF has probably a similar form of trypsin-like enzymes. On study of comparison of enzyme activity between the BSF and the housefly using the apiZYM kit, the BSF had more strongly digestive enzyme activity than one of the housefly about leucine arylamidase, alpha-galactosidase, beta-galactosidase, alpha-mannosidase and alpha-fucosidase. This finding supports that the BSF can ingest raw waste far more efficiently than any other known species of fly as reported previously.
A 18–40 GHz Substrate Integrated Waveguide H-Plane Horn Antenna
Park, Won Bin,Lee, Jong Min,Lee, Sungwoo,Park, Young Mi,Hwang, Keum Cheol IEEE 2018 IEEE transactions on antennas and propagation Vol.66 No.11
<P>A 18–40 GHz wideband substrate integrated waveguide (SIW) H-plane horn antenna is proposed for applications on both the K- and Ka-bands. By employing a grating transition in front of the horn aperture, the impedance bandwidth (IBW) of the proposed antenna is broadened considerably. A broadband double-ridge waveguide (DRW)-to-SIW transition is also developed as the feeding structure for the proposed SIW H-plane horn antenna. The DRW is adopted to support a wider IBW as compared to that of a rectangular waveguide. A prototype of the proposed antenna is experimentally verified. The measured results show that the IBW for <TEX>$|S_{11}| \leq -10$</TEX> dB ranges from 18 GHz to more than 40 GHz, covering the entire K- and Ka-bands. The measured gain varies from 7.52 to 15.37 dBi with an average gain of 11.58 dBi. In addition, the endfire radiation patterns are observed and maintained within the IBW.</P>
Thucydides on the Fate of the Democratic Empire
Sungwoo Park 서울대학교 국제학연구소 2008 Journal of International and Area Studies Vol.15 No.1
This paper investigates Thucydides" instruction on the problematic concept of the democratic empire. Although the term ""democratic empire, "" that is, the combination of democracy and empire, is often justified in the modern context, it appeared to the ancient to be very problematic because of its inherent contradiction. The paper examines how Thucydides dealt with the Athenian Empire as an exemplary case of democratic empire. More specifically it examines how Thucydides related the rise and fall of the Athenian Empire to its characteristics of democratic empire. Many scholars attributed the collapse of the Empire to the excessive desire of the demos. I do not deny this traditional reading. Yet I argue that the Athenian demos was fully aware of what it was doing: it preferred democracy to empire when it had to choose either. By reading closely Thucydides I try to show how the Athenian demos constantly maintained democracy even when its preference for democracy could endanger its empire. Based on this reading of Thucydides, I conclude that Thucydides instructs both democratic citizens and imperialist elites that they cannot maintain democratic empire in the long run: they should choose democracy or imperialism at a certain point.
Platonic Rhetoric as a Philosophical Response to Parrhesia
Sungwoo Park 한국서양고전학회 2019 西洋古典學硏究 Vol.58 No.3
This paper examines how Plato develops a specific concept of rhetoric and how he accomplishes both philosophical and political goals with his own version of rhetoric. Section I situates Plato’s interest in rhetoric in the Greek context and gives a brief overview of the paper. Section II introduces the practice of parrhesia and points out some of its defects as a democratic practice. Section III illustrates how Plato responds to the problems of parrhesia by replacing it with philosophical parrhesia through the prism of Plato’s Laches. Section IV examines Gorgias to see how Plato deliberately combines irony and parrhesia for philosophical and a political purposes. Section V investigates Plato’s description of democracy in the Republic to show how his scheme for parrhesia works in democratic regime in terms of both maintaining philosophy and reforming politics.
Characterization of CCND1 and TWIST1 as Prognostic Markers with the Mortality Rate of Breast Cancer
Sungwoo Ahn,Sangjung Park,Hye-Young Wang,Sunyoung Park,Jungho Kim,Hyeyoung Lee 대한의생명과학회 2018 Biomedical Science Letters Vol.24 No.2
Breast cancer is one of the most common cancers affecting women worldwide. Although the survival rate of breast cancer has increased, breast cancer still results in a high mortality rate. Breast cancer deaths are caused by metastasis that occurs in organ dysfunction. Recently, there have been many studies on circulating tumor cells (CTCs), which are related to breast cancer metastasis in the blood. Recent studies have demonstrated that some CTCs do not express epithelial markers. Therefore, in this study, total RNA was extracted from blood without separating out the CTCs, and the characteristics of the CTCs were analyzed by RT-qPCR. Cyclin D1 and twist-related protein 1 (TWIST1) are well-known markers for predicting the prognosis of patients with breast cancer. However, few studies have demonstrated the use of CCND1 and TWIST1 in blood as diagnostic and prognostic markers of breast cancer. In this study, patients with late-stage breast cancer had overexpressed CCND1 and TWIST1 than patients with different stages of breast cancer (P < 0.001 and P < 0.01, respectively). The relative expression level of CCND1 in survivors was higher than in patients who died (P = 0.06). The relative expression level of TWIST1 in survivors was lower than in patients who died (P = 0.08). Overall CCND1 and TWIST1 were not useful as markers for the diagnosis of breast cancer through blood. However, we showed the possibility of using CCND1 and TWIST1 as prognostic markers, and a large-scale study is needed to confirm the usefulness of these prognostic markers.
Type-safe higher-order channels with channel locality
PARK, SUNGWOO,IM, HYEONSEUNG Cambridge University Press 2009 Journal of functional programming Vol.19 No.1
<B>Abstract</B><P>As a means of transmitting not only data but also code encapsulated within functions, higher-order channels provide an advanced form of task parallelism in parallel computations. In the presence of mutable references, however, they pose a safety problem because references may be transmitted to remote threads where they are no longer valid. This paper presents an ML-like parallel language with <I>type-safe</I> higher-order channels. By type safety, we mean that no value written to a channel contains references, or equivalently, that no reference escapes via a channel from the thread where it is created. The type system uses a typing judgment that is capable of deciding whether the value to which a term evaluates contains references or not. The use of such a typing judgment also makes it easy to achieve another desirable feature of channels, <I>channel locality</I>, that associates every channel with a unique thread for serving all values addressed to it. Our type system permits mutable references in sequential computations and also ensures that mutable references never interfere with parallel computations. Thus, it provides both flexibility in sequential programming and ease of implementing parallel computations.</P>
Improved Etch Characteristics of Magnetic Tunneling Junction Materials by Using Helium
Park, Sungwoo,Yang, Kyungchae,Lee, Hoseok,Kim, Dongwoo,Baek, Jongung,Shim, Taehun,Park, Jeagun,Yeom, Geunyoung The Electrochemical Society 2017 ECS journal of solid state science and technology Vol.6 No.9
<P>The etch characteristics of magnetic tunneling junction (MTJ) materials for spin transfer torque magnetic random access memory (STT-MRAM) using He inductively coupled plasma (ICP) were compared with the etch characteristics of ICP using Ar or CO/NH<SUB>3</SUB> (1:3). The ICP etching using He showed a higher etch selectivity of CoFeB over W and a more anisotropic etch profile compared to the etching using Ar at similar etch rates. The sputter etch characteristics of CoFeB and W were also investigated using the Stopping and Range of Ions in Matter (SRIM) simulation program. The results showed higher sputter etch selectivity of CoFeB over W in addition to narrower angular distribution of the sputtered atoms than those obtained using Ar. The etching of MTJ materials using CO/NH<SUB>3</SUB> (1:3) ICP exhibited good MTJ etch characteristics comparable to He ICP, however, the MTJ etched using CO/NH<SUB>3</SUB> (1:3) showed the lowest saturation magnetization (M<SUB>S</SUB>) measured by a vibrating-sample magnetometer (VSM) possibly due to the sidewall oxidation of MTJ while the M<SUB>S</SUB> values of the MTJ etched using He and Ar are similar. It is found that, by etching the MTJ materials using He ICP with the ion energy near the hardmask sputter threshold energy, highly anisotropic etch profiles could be obtained without forming the sidewall redeposited materials and without significant degradation of magnetic properties.</P>