Aire's plant homeodomain(PHD)-2 is critical for induction of immunological tolerance.

Yang, Siyoung,Bansal, Kushagra,Lopes, Jared,Benoist, Christophe,Mathis, Diane National Academy of Sciences 2013 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.110 No.5

<P>Aire impacts immunological tolerance by regulating the expression of a large set of genes in thymic medullary epithelial cells, thereby controlling the repertoire of self-antigens encountered by differentiating thymocytes. Both humans and mice lacking Aire develop multiorgan autoimmunity. Currently, there are few molecular details on how Aire performs this crucial function. The more amino-terminal of its two plant homeodomains (PHDs), PHD1, helps Aire target poorly transcribed loci by 'reading' the methylation status of a particular lysine residue of histone-3, a process that does not depend on the more carboxyl-terminal PHD-2. This study addresses the role of PHD2 in Aire function by comparing the behavior of wild-type and PHD2-deleted Aire in both transfected cells and transgenic mice. PHD2 was required for Aire to interact with sets of protein partners involved in chromatin structure/binding or transcription but not with those implicated in pre-mRNA processing; it also was not required for Aire's nuclear translocation or regional distribution. PHD2 strongly influenced the ability of Aire to regulate the medullary epithelial cell transcriptome and so was crucial for effective central tolerance induction. Thus, Aire's two PHDs seem to play distinct roles in the scenario by which it assures immunological tolerance.</P>

Hypoxia-inducible factor-2α is a catabolic regulator of osteoarthritic cartilage destruction

Yang, Siyoung,Kim, Jonghwan,Ryu, Je-Hwang,Oh, Hwanhee,Chun, Churl-Hong,Kim, Byoung Ju,Min, Byoung Hyun,Chun, Jang-Soo Nature Publishing Group 2010 Nature medicine Vol.16 No.6

<P>Osteoarthritic cartilage destruction is caused by an imbalance between anabolic and catabolic factors. Here, we show that hypoxia-inducible factor-2 alpha (HIF-2 alpha, encoded by EPAS1) is a catabolic transcription factor in the osteoarthritic process. HIF-2 alpha directly induces the expression in chondrocytes of genes encoding catabolic factors, including matrix metalloproteinases (MMP1, MMP3, MMP9, MMP12 and MMP13), aggrecanase-1 (ADAMTS4), nitric oxide synthase-2 (NOS2) and prostaglandin-endoperoxide synthase-2 (PTGS2). HIF-2 alpha expression was markedly increased in human and mouse osteoarthritic cartilage, and its ectopic expression triggered articular cartilage destruction in mice and rabbits. Moreover, mice transgenic for Epas1 only in chondrocytes showed spontaneous cartilage destruction, whereas heterozygous genetic deletion of Epas1 in mice suppressed cartilage destruction caused by destabilization of the medial meniscus (DMM) or collagenase injection, with concomitant modulation of catabolic factors. Our results collectively demonstrate that HIF-2 alpha causes cartilage destruction by regulating crucial catabolic genes.</P>

Fine edge-preserving technique for display devices

Siyoung Yang,Yongha Kim,Jechang Jeong IEEE 2008 IEEE transactions on consumer electronics Vol.54 No.4

<P>In this paper, we propose a fine edge preserving image interpolation algorithm based on local gradient features. The proposed algorithm determines the edge direction using horizontal and vertical gradient operators, and then the edge direction is conceptually changed to the position between adjacent pixels. Since our algorithm is independent of interpolation kernels, various conventional kernels can be implemented. Experimental results show that the proposed methods can preserve clear edges and reduce blurring artifacts.</P>

NAMPT (visfatin), a direct target of hypoxia-inducible factor-2α, is an essential catabolic regulator of osteoarthritis

Yang, Siyoung,Ryu, Je-Hwang,Oh, Hwanhee,Jeon, Jimin,Kwak, Ji-Sun,Kim, Jin-Hong,Kim, Hyun Ah,Chun, Churl-Hong,Chun, Jang-Soo H. K. Lewis 2015 Annals of the rheumatic diseases Vol.74 No.3

<P><B>Objective</B></P><P>Hypoxia-inducible factor 2α (HIF-2α), encoded by <I>Epas1</I>, causes osteoarthritic cartilage destruction by regulating the expression of matrix-degrading enzymes. We undertook this study to explore the role of nicotinamide phosphoribosyltransferase (NAMPT or visfatin) in HIF-2α-mediated osteoarthritic cartilage destruction.</P><P><B>Methods</B></P><P>The expression of HIF-2α, NAMPT and matrix-degrading enzymes was determined at the mRNA and protein levels in human osteoarthritis (OA) cartilage, mouse experimental OA cartilage and primary cultured mouse chondrocytes. Experimental OA in mice was induced by destabilisation of the medial meniscus (DMM) surgery or intra-articular injection of Ad-<I>Epas1</I> or Ad-<I>Nampt</I> in wild-type, <I>Epas1</I><SUP>+/−</SUP>, <I>Epas1</I><SUP>fl/fl</SUP>;<I>Col2a1-Cre</I> and <I>Col2a1-Nampt</I> transgenic (TG) mice. Primary cultured mouse chondrocytes were treated with recombinant NAMPT protein or were infected with adenoviruses.</P><P><B>Results</B></P><P>We found that the <I>Nampt</I> gene is a direct target of HIF-2α in articular chondrocytes and OA cartilage. NAMPT protein, in turn, increased mRNA levels and activities of MMP3, MMP12 and MMP13 in chondrocytes, an action that was necessary for HIF-2α-induced expression of catabolic enzymes. Gain-of-function studies (intra-articular injection of Ad-<I>Nampt; Col2a1-Nampt</I> TG mice) and loss-of-function studies (intra-articular injection of the NAMPT inhibitor FK866) demonstrated that NAMPT is an essential catabolic regulator of osteoarthritic cartilage destruction caused by HIF-2α or DMM surgery.</P><P><B>Conclusions</B></P><P>Our findings indicate that NAMPT, whose corresponding gene is a direct target of HIF-2α, plays an essential catabolic role in OA pathogenesis and acts as a crucial mediator of osteoarthritic cartilage destruction caused by HIF-2α or DMM surgery.</P>

Fungi Associated with the Traditional Starter Cultures Used for Rice Wine in Korea

Siyoung Yang,이정관,Jungki Kwak,Kihyun Kim,Minjae Seo,이인원 한국응용생명화학회 2011 Applied Biological Chemistry (Appl Biol Chem) Vol.54 No.6

The ‘Nuruk’ starter culture has been used for many years in the fermentation of rice wine in Korea. In present study, mycobiota in Nuruk cultures was identified by performing morphological, physiological, and phylogenetical analyses. Mucorales was the most common mycobiota in Nuruk,followed by yeast and Aspergillus. The composition of fungal species in Nuruk was different among samples and did not correlate with the geographical location from where the Nuruk culture was manufactured. For more detailed identification, 174 filamentous fungal strains were isolated from 39 Nuruk samples. Although the morphological and molecular analyses showed that the strains were identical at the genus level, some discordance was identified between species. Of the 174strains, 160 showed thermotolerance, and the level of thermotolerance matched the clade generated by phylogenetic analysis. Six genera (Lichtheimia, Aspergillus, Rhizopus, Rhizomucor, Mucor, and Syncephalastrum) and 17 fungal species were identified. Among the genera, the genus Syncephalastrum had not been previously identified in Nuruk cultures, and the isolate was identified as Syncephalastrum racemosum. Two genera, Lichtheimia and Aspergillus, comprised approximately 84% of the filamentous fungal isolates from the Nuruk samples, and Lichtheimia ramosa and Aspergillus oryzae were the most commonly found species. The controversy regarding the presence of mycobiota in Nuruk starter cultures was addressed, and results showed that Nuruk contains unique mycobiota not yet found in other Asian starter cultures.

Regulatory T cells generated early in life play a distinct role in maintaining self-tolerance

Yang, Siyoung,Fujikado, Noriyuki,Kolodin, Dmitriy,Benoist, Christophe,Mathis, Diane American Association for the Advancement of Scienc 2015 Science Vol.348 No.6234

<P><B>Early T cells keep autoimmunity at bay</B></P><P>A major challenge faced by the immune system is to react to foreign substances, such as microbes, while simultaneously tolerating the self. Upsetting this balance leads to autoimmunity. Regulatory T cells (T<SUB>regs</SUB>), are a subset of immune cells that help to maintain this balance. Yang <I>et al.</I> found that murine T<SUB>reg</SUB> cells generated very early in life are distinct from those generated in older animals and play an especially important role in keeping autoimmunity in check (see the Perspective by Tanaka and Sakaguchi). These changes are due to differences in the way T<SUB>regs</SUB> develop in the thymus in newborn versus adult mice.</P><P><I>Science</I>, this issue p. 589; see also p. 506</P><P>Aire is an important regulator of immunological tolerance, operating in a minute subset of thymic stromal cells to induce transcripts encoding peptides that guide T cell selection. Expression of Aire during a perinatal age window is necessary and sufficient to prevent the multiorgan autoimmunity characteristic of Aire-deficient mice. We report that Aire promotes the perinatal generation of a distinct compartment of Foxp3<SUP>+</SUP>CD4<SUP>+</SUP> regulatory T (T<SUB>reg</SUB>) cells, which stably persists in adult mice. This population has a role in maintaining self-tolerance, a transcriptome and an activation profile distinguishable from those of T<SUB>regs</SUB> produced in adults. Underlying the distinct T<SUB>reg</SUB> populations are age-dependent, Aire-independent differences in the processing and presentation of thymic stromal-cell peptides, resulting in different T cell receptor repertoires. Our findings expand the notion of a developmentally layered immune system.</P>

쥐노래미 (Hexagrammos otakii )에 대한 초음파 산란강도 측정

양시영(Siyoung YANG),윤소희(So-hui YUN),윤은아(Eun-a YOON),황두진(Doojin HWANG) 전남대학교 어업기술연구소 2017 어업기술연구소보고지 Vol.10 No.1

The purpose of this study is to obtain the most basic data, acoustic scattering characteristic of the greenling (Hexagrammos otakii) TS was measured in acoustic seawater tank (5 m(L) × 5 m(H) × 5 m(D)) at the fisheries science institute of Chonnam National University, Korea. Acoustic data was collected with a 70 kHz and 120 kHz quantitative echo sounder. The echo sounder is installed on the water tank, and the camera is installed on the side of the water tank and recorded every 0.5 seconds. The greenling was ranged from 19.5 to 34.5 cm in length and from 75.02 to 557.54 g in wet weight. The relationship between fish total length and TS were as follows : TS70 kHz = 37.79log(L)-100.52 (R² = 0.62) and TS120 kHz = 21.79log(L)-78.55 (R² = 0.77). This data can be provided as a basis for estimating density and biomass of greenling.

프레임율 변환을 위한 개선된 트랜스코딩 기법

양시영(Siyoung Yang),정제창(Jechang Jeong) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.7C

네트워크에 의해서 필요한 비트율로 줄이거나 터미널의 제한된 한계를 만족하기 위해서, 비디오 비트 스트림의 시간적 해상도를 줄이는 것이 사용된다. 본 논문에서는 압축된 비디오 스트림의 감소된 해상도 트랜스코딩의 문제점에 대해서 논의하고, 시간적 해상도 변환을 위한 트랜스코딩 기법을 논의한다. 트랜스코딩의 속도를 증가시키기 위해서, 비디오 트랜스코더는 보통 입력된 비디오 스트림으로부터의 움직임 벡터를 재사용한다. 본 논문에서는 코딩된 프레임의 높은 화질을 유지하기 위해서 강화된 움직인 재추정 기법을 제안한다. 실험결과는 감소된 프레임율을 가진 비디오 트랜스코더를 위한 저 복잡도를 가지면서도 성능이 개선된 것을 보여준다. To reduce the bit-rate requirements imposed by a network or satisfy processing limitations imposed by a terminal, Conversion the temporal resolution of a video bit stream is a technique that may be used. This paper discusses the problem of reduced resolution transcoding of compressed video bit streams, and discussed the technique for temporal transcoding. To speed up this operation, a video transcoder usually reuses the coded motion vectors from the input video bit stream. In this paper we propose an enhanced motion re-estimation technique to maintain higher quality of coded frames. The performance of experimental results can be improved while maintaining low computational complexity for a reduced frame rate video transcoder.

가상환경용 3차원 입체음향 시스템 개발

양시영(Siyoung Yang),김동형(Donghyung Kim),정제창(Jechang Jeong) 한국방송·미디어공학회 2008 방송공학회논문지 Vol.13 No.5

의료영상의 JPEG 압축을 위한 양자화 테이블과 허프만 테이블 설계

梁時寧(Siyoung Yang),鄭濟昌(Jechang Jeong),朴尙奎(Sang Kyu Park) 대한전기학회 2004 전기학회논문지 D Vol.53 No.6