Disruption of a regulatory loop between DUSP1 and p53 contributes to hepatocellular carcinoma development and progression

Hao, P.P.,Li, H.,Lee, M.J.,Wang, Y.P.,Kim, J.H.,Yu, G.R.,Lee, S.Y.,Leem, S.H.,Jang, K.Y.,Kim, D.G. Elsevier Science Publishers 2015 Journal of hepatology Vol.62 No.6

Background & Aims: Altered expression of dual specificity phosphatase 1 (DUSP1) is common in tumors including hepatocellular carcinoma (HCC), and is predictive of tumor progression and poor prognosis. However, the tumor suppressive role of DUSP1 has yet to be clearly elucidated. Methods: The molecular mechanisms of tumor suppression that were investigated were induction of apoptosis, cell cycle inhibition, and regulation of p53. Additionally, the antitumor effect of DUSP1 was assessed using a mouse model. Associated signaling pathways in HCC cells and tissues were examined. Results: Downregulation of DUSP1 expression was significantly correlated with poor differentiation (p<0.001) and advanced HCC stage (p=0.023). DUSP1 expression resulted in HCC suppression and longer survival (p=0.0002) in a xenoplant mice model. DUSP1 inhibited p38 MAPK phosphorylation and subsequently suppressed HSP27 activation, resulting in enhanced p53 phosphorylation at sites S15, S20, and S46 in HCC cells. Enhanced p53 activation induced the expression of target genes p21 and p27, which are linked to cell cycle arrest and apoptosis. Thus, DUSP1 was potentially linked to p53 activation via the p38 MAPK/HSP27 pathway. Wild-type but not mutant p53 transcriptionally upregulated DUSP1 via its DNA-binding domain. DUSP1 and p53 might collaborate to suppress tumors in hepatocarcinogenesis via a positive regulatory loop. Conclusions: Our results revealed that disruption of a positive regulatory loop between DUSP1 and p53 promoted HCC development and progression, providing a rationale for a therapeutic agent that restores DUSP1 in HCC.

On dual processes of non-symmetric diffusions with measure-valued drifts

Kim, P.,Song, R. North-Holland Pub. Co ; Elsevier Science Ltd 2008 Stochastic processes and their applications Vol.118 No.5

For μ=(μ<SUP>1</SUP>,...,μ<SUP>d</SUP>) with each μ<SUP>i</SUP> being a signed measure on R<SUP>d</SUP> belonging to the Kato class K<SUB>d,1</SUB>, a diffusion with drift μ is a diffusion process in R<SUP>d</SUP> whose generator can be formally written as L+μ@?@? where L is a uniformly elliptic differential operator. When each μ<SUP>i</SUP> is given by U<SUP>i</SUP>(x)dx for some function U<SUP>i</SUP>, a diffusion with drift μ is a diffusion in R<SUP>d</SUP> with generator L+U@?@?. In [P. Kim, R. Song, Two-sided estimates on the density of Brownian motion with singular drift, Illinois J. Math. 50 (2006) 635-688; P. Kim, R. Song, Boundary Harnack principle for Brownian motions with measure-valued drifts in bounded Lipschitz domains, Math. Ann., 339 (1) (2007) 135-174], we have already studied properties of diffusions with measure-valued drifts in bounded domains. In this paper we first show that the killed diffusion process with measure-valued drift in any bounded domain has a dual process with respect to a certain reference measure. We then discuss the potential theory of the dual process and Schrodinger-type operators of a diffusion with measure-valued drift. More precisely, we prove that (1) for any bounded domain, a scale invariant Harnack inequality is true for the dual process; (2) if the domain is bounded C<SUP>1,1</SUP>, the boundary Harnack principle for the dual process is valid and the (minimal) Martin boundary for the dual process can be identified with the Euclidean boundary; and (3) the harmonic measure for the dual process is locally comparable to that of the h-conditioned Brownian motion with h being an eigenfunction corresponding to the largest Dirichlet eigenvalue in the domain. The Schrodinger operator that we consider can be formally written as L+μ@?@?+ν where L is uniformly elliptic, μ is a vector-valued signed measure on R<SUP>d</SUP> and ν is a signed measure in R<SUP>d</SUP>. We show that, for a bounded Lipschitz domain and under the gaugeability assumption, the (minimal) Martin boundary for the Schrodinger operator obtained from the diffusion with measure-valued drift can be identified with the Euclidean boundary.

Down-regulation of p21-activated kinase 1 by progestin and its increased expression in the eutopic endometrium of women with endometriosis

Kim, S. H.,Lee, H. W.,Kim, Y. H.,Koo, Y. H.,Chae, H. D.,Kim, C. H.,Lee, P. R.,Kang, B. M. Oxford University Press 2009 Human reproduction Vol.24 No.5

<P>BACKGROUND: P21-activated kinase 1 (Pak1) integrates various signaling pathways that are vital to cell survival and function. This study was performed to evaluate whether sex steroids may regulate the expression of Pak1 in endometrial cells as well as whether its expression is increased in the eutopic endometrium of women with endometriosis. METHODS: Following in vitro estradiol (E(2)) and/or medroxyprogesterone acetate (MPA) treatment of Ishikawa cells and endometrial stromal cells (ESCs), Pak1 protein was analyzed utilizing western blot analysis and immunocytochemistry. Immunohistochemistry was performed to evaluate Pak1 immunoreactivity semiquantitatively in women with endometriosis and in controls. To assess the role of Pak1 on endometrial cell viability, crystal violet assay was performed following transfection of Ishikawa cells with Pak1 small interfering RNA (siRNA). RESULTS: In vitro treatment with E(2) plus MPA or MPA alone led to a significant decrease of Pak1 protein in Ishikawa cells and ESCs (both P < 0.05 versus control). Immunohistochemistry also revealed that Pak1 protein is significantly decreased during the secretory phase in both epithelial and stromal cells in the control subjects (P < 0.001 and P < 0.01, respectively). The immunoreactivity of Pak1 in glandular cells was significantly increased in the eutopic endometrium of women with endometriosis compared with the controls during the secretory phase (P < 0.01). Crystal violet assay has shown that transfection of Ishikawa cells with Pak1 siRNA led to a significant decrease of cellular viability (P < 0.05). CONCLUSIONS: These findings suggest that Pak1 is down-regulated by progesterone during the secretory phase in normal endometrium and increased Pak1 activity during the secretory phase might lead to establishment of endometriosis.</P>

Isostructural metal-insulator transition in VO₂

Lee, D.,Chung, B.,Shi, Y.,Kim, G.-Y.,Campbell, N.,Xue, F.,Song, K.,Choi, S.-Y.,Podkaminer, J. P.,Kim, T. H.,Ryan, P. J.,Kim, J.-W.,Paudel, T. R.,Kang, J.-H.,Spinuzzi, J. W.,Tenne, D. A.,Tsymbal, E. Y. American Association for the Advancement of Scienc 2018 Science Vol.362 No.6418

<P><B>Separating structure and electrons in VO<SUB>2</SUB></B></P><P>Above 341 kelvin—not far from room temperature—bulk vanadium dioxide (VO<SUB>2</SUB>) is a metal. But as soon as the material is cooled below 341 kelvin, VO<SUB>2</SUB> turns into an insulator and, at the same time, changes its crystal structure from rutile to monoclinic. Lee <I>et al.</I> studied the peculiar behavior of a heterostructure consisting of a layer of VO<SUB>2</SUB> placed underneath a layer of the same material that has a bit less oxygen. In the VO<SUB>2</SUB> layer, the structural transition occurred at a higher temperature than the metal-insulator transition. In between those two temperatures, VO<SUB>2</SUB> was a metal with a monoclinic structure—a combination that does not occur in the absence of the adjoining oxygen-poor layer.</P><P><I>Science</I>, this issue p. 1037</P><P>The metal-insulator transition in correlated materials is usually coupled to a symmetry-lowering structural phase transition. This coupling not only complicates the understanding of the basic mechanism of this phenomenon but also limits the speed and endurance of prospective electronic devices. We demonstrate an isostructural, purely electronically driven metal-insulator transition in epitaxial heterostructures of an archetypal correlated material, vanadium dioxide. A combination of thin-film synthesis, structural and electrical characterizations, and theoretical modeling reveals that an interface interaction suppresses the electronic correlations without changing the crystal structure in this otherwise correlated insulator. This interaction stabilizes a nonequilibrium metallic phase and leads to an isostructural metal-insulator transition. This discovery will provide insights into phase transitions of correlated materials and may aid the design of device functionalities.</P>

Upregulation of duck interleukin-17A during Riemerella anatipestifer infection

Fernandez, C.P.,Kim, W.H.,Diaz, J.A.R.,Jeong, J.,Afrin, F.,Kim, S.,Jang, H.K.,Lee, B.H.,Yim, D.,Lillehoj, H.S.,Min, W. Pergamon Press ; Elsevier Science 2016 DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY Vol.63 No.-

<P>Although IL-17 cytokines play critical roles in host defense immunity, dysregulated expression of these cytokines is associated with inflammation and autoimmune diseases. Riemerella anatipestifer is the most important infectious bacterium in the duck industry. Interestingly, not all avian species are equally susceptible to R. anatipestifer infection. This paper reports the first description of mortality rate, bacterial burden, and expression profiles of immune-related genes between ducks and chickens infected with R. anatipestifer. Ducks exhibited increased susceptibility to R. anatipestifer infection compared to chickens, as determined by mortality rate and bacterial burden. Comparative expression analyses of immune-related genes in R. anatipestifer-infected tissues obtained from both species revealed that TLR3, TLR7, IL-2, IL-4, and IFN-gamma transcript levels were higher in chickens, whereas TLR4 and IL-17A transcript levels were higher in ducks. Marked increases in expression of IL-17A and IL-6, but not TGF-beta, were associated with Th17 cell differentiation in duck splenic lymphocytes, but not in chicken splenic lymphocytes, stimulated with R. anatipestifer. Moreover, upregulation of IL-1 beta, IL-6, and IL-17A mRNA expressions, but not TGF-beta, was confirmed in the liver and spleen of ducks infected with R. anatipestifer, indicating that IL-17A is strongly associated with Riemerella infection in ducks. (C) 2016 Elsevier Ltd. All rights reserved.</P>

<i>In vitro</i> inhibitory effects of Wen‐pi‐tang‐Hab‐Wu‐ling‐san on human cytochrome P450 isoforms

Lee, H. W.,Kim, D. W.,Phapale, P. B.,Lim, M. ‐,S.,Park, J.,Seo, J. J.,Park, K. M.,Park, Y. ‐,K.,Yoon, Y. ‐,R. Blackwell Publishing Ltd 2011 Journal of clinical pharmacy and therapeutics Vol.36 No.4

<P><B>Summary</B></P><P><B>What is known and Objective: </B> Although Wen‐pi‐tang‐Hab‐Wu‐ling‐san (WHW), an oriental herbal medicine, has been prescribed for the treatment of chronic renal failure (CRF) in Korean clinics, no studies regarding WHW–drug interactions had been reported. The purpose of this study was to evaluate the possibility that WHW inhibits the catalytic activities of major cytochrome P450 (CYP) isoforms.</P><P><B>Methods: </B> The abilities of various WHW extracts to inhibit phenacetin O‐de‐ethylation (CYP1A2), tolbutamide 4‐methylhydroxylation (CYP2C9), omeprazole 4′‐hydroxylation (CYP2C19), dextromethorphan O‐demethylation (CYP2D6), chlorzoxazone 6‐hydroxylation (CYP2E1) and midazolam 1‐hydroxylation (CYP3A4) were assessed using human liver microsomes.</P><P><B>Results and Discussion: </B> WHW extract at concentrations up to 100 μ<SMALL>m</SMALL> showed negligible inhibition of the six CYP isoforms tested (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4), with apparent IC<SUB>50</SUB> values (concentration of the inhibitor causing 50% inhibition of the original enzyme activity) of 817.5, 601.6, 521.7, 310.2, 342.8 and 487.0 μg/mL, respectively.</P><P><B>What is new and Conclusion: </B> Our <I>in vitro</I> findings suggest that WHW extract at concentrations corresponding to a clinically recommended dosage range has no notable inhibitory effects on CYP isoforms. Therefore, we believe that WHW extract may be free of drug–herb interactions when co‐administered with other medicines. However, <I>in vivo</I> human studies are needed to confirm these results.</P>

Effects of Different Dietary Acidifier Sources of Calcium and Phosphorus on Ammonia, Methane and Odorant Emission from Growing-finishing Pigs

Kim, I.B.,Ferke, P.R.,Powers, W.J.,Stein, H.H.,Van Kempe, T.A.T.G. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.8

The objective of this study was to investigate the effects of different sources of Ca and P on urine and ileal digesta pH, and ammonia ($NH_{3}$), methane ($CH_{4}$), and odor emission. In experiment 1, eight pigs (commercial three-way cross; initial BW 67$\pm$3 kg) were arranged in a repeated 4$\times$4 Latin Square design. All pigs were equipped with a T-cannula in the distal ileum. Four corn-soybean meal based diets were formulated. Diet 1 was the control in which dicalcium phosphate (DCP) and limestone ($CaCO_{3}$) were used as the sources of inorganic P and Ca. In Diets 2 and 3, ${H_{3}}{PO_{4}}$, monocalcium phosphate (MCP), and $CaSO_{4}$replaced DCP and $CaCO_{3}$ as the inorganic sources of P and Ca. Diet 4 was similar to Diet 1 except that it was fortified with HCl to provide an acid load similar to that of diet 2. Urine and ileal digesta pH were determined in pigs fed each of these diets. In Exp. 1, urine pH decreased (p<0.05) in animals consuming diets containing ${H_{3}}{PO_{4}}$-$CaSO_{4}$ (5.85$\pm$0.38) and MCP-$CaSO_{4}$(5.73$\pm$0.30) compared with the DCP-$CaCO_{3}$ diet (6.89$\pm$0.24). In the pigs consuming ${H_{3}}{PO_{4}}$-$CaSO_{4}$, ileal digesta pH decreased compared with the control (5.52$\pm$0.28 vs. 6.66$\pm$0.17; p<0.05). Based on the results of Exp. 1, a total of four trials were performed in environmental chambers for determining how $NH_{3}$, $NH_{4}$, and odor were affected by the different dietary Ca and P sources (Exp. 2). In Exp. 2, pigs fed the ${H_{3}}{PO_{4}}$-$CaSO_{4}$ diet had decreased (30%) $NH_{3}$ emissions compared with the control (p<0.05). Also, a combination of MCP-$CaCO_{3}$-$CaCl_{12}$ decreased $NH_{3}$ emission by 15% (p<0.05). Emission of $CH_{4}$ was decreased only with the ${H_{3}}{PO_{4}}$-$CaSO_{4}$ diet with 14% (p<0.05). Odorant emission of phenolics and volatile fatty acids increased roughly three-fold with the DCP-$CaSO_{4}$ diet but was not affected by other test diets. In conclusion, acidogenic Ca and P sources in swine diets can decrease the urinary pH and reduce $NH_{3}$ and $CH_{4}$ emission from swine facilities.

Prevalences of Clonorchiasis and Metagonimiasis along Rivers in Jeonra-Nam-Do, Korea

Soh, C.T.,Lee, K.T.,Cho, K.M.,Ahn, Y.K.,Kim, S.J.,Chung, P.R.,Im, K.I.,Min, D.Y.,Lee, J.H.,Chang, J.K. INSTITUTE OF TROPICAL MEDICINE YONSEI UNIVERSITY 1976 YONSEI REPORTS ON TROPICAL MEDICINE Vol.7 No.1

전라남도 영산강 및 섬진강유역 주민의 간디스토마와 요꼬가와흡충 감염율의 조사 및 이들 패류매개성 기생충의 제1, 제2 중간숙주를 조사한 바 그 성적을 요약하면 다음과 같다(조사기간: 1975년 8,9월, 1976년 7,8월). 영산강 유역 영산강을 상류(YU), 중류(YM), 하류(YD)로 삼분하여 10개 표본지역을 선정, 조사하였다(표 1 참조). 상류는 광산군 송정읍의 상부지역으로 장성군과 담양군이 이에 해당되며 중류는 송정읍과 나주군 영산포읍 사이의 지역으로 광산군 일부와 나주군이 이에 해당되며 하류는 영산포읍이하의 나주군 일부와 함평군이 이에 해당된다. 1. 주민의 감열율 : 상류 3개지역, 중류 1개지역 그리고 하류 2개지역 등 6개지역 주민 359명을 대상으로 조사하였다. 상류지역의 간디스토마 감염율은 29.9%(69/231), 중류 38.5%(20/52), 하류 21.1%(16/76)이었다. 전체적으로는 29.2%(105/359)의 감염율을 나타내었으며 남자는 39.3%(79/201), 여자 15.4%(21/136)로 전자가 2.5배 이상의 감염상을 보였다. 2. 제 1 중간숙주 : 간디스토마의 제 1 중간숙주인 왜우렁(Parafossarulus manchouricus)의 조사는 상류 2개지역, 중류 4개지역, 하류 1개지역등 7개지역에서 채집한 980개를 검사하였으며 그 중 11개(1.1%)에서 간디스토마셀카리아를 검출하였다. 지역별로는 상류 1.8%(6/333), 중류 0.9%(5/553)가 양성이었으나 하류지역의 94개에서는 모두 음성이었다. 요꼬가와흡충의 제 1 중간숙주인 다슬기(Semisulcospira libertina)를 상, 중, 하류의 각 1개지역씩 3개지역에서 모두 179개를 채집하여 검사하였으나. 요꼬가와흡충 또는 페디스토마의 셀카리아는 검출할 수 없었다. 3. 제 2 중간숙주 : 전지역에서 9종의 담수어 263마리를 포획하여 검사한바 간디스토마메타셀카리아의 양성율은 참붕어에서 62.9%(22/35), 피리 5.7%(3/53), 납지리류 21.9%(7/32), 돌고기 17.6%(3/17), 그리고 끄리에서 14.3%(1/7)이었으나 붕어, 모래무지, 버들붕어 및 꺽지 등에서는 검출할 수 없었다. 요꼬가와흡충의 제2중간숙주인 은어는 채집 또는 포획할 수 없었다. 섬진강유역 전라남도 관내의 섬진강을 상, 중, 하류로 구분하여 각 유역별로 2개지역씩 선정, 6개지역에서 조사하였다(표 1 참조). Soh, C.T. et al. 표 1. 영산강 및 섬진강 유역 조사대상 지역 =================================================================================== 영산강 유역 ∥ 섬진강 유역 ------------------------------------------∥--------------------------------------- 지 역 *조사내용 ∥ 지 역 *조사내용 ------------------------------------------∥--------------------------------------- 상류 1. 장성군 황룡면 황룡리 P. 1.2. ∥상류 1. 곡성군 곡성면 동산리 P. 1. 2. 담양군 봉산면 삼지리 P. 1.2. ∥ 2. 곡성군 곡성면 석곡리 P. 1.2. 3. 담양군 금성면 금월리 P. ∥ 중류 1. 나주군 영산포읍 1. ∥중류 1. 구례군 구례읍 신월리 P. 1.2. 2. 나주군 산포면 산제리 1.2. ∥ 2. 곡성군 곡성면 압록리 2. 3. 나주군 남평면 남평리 1.2. ∥ 4. 광산군 동곡면 복용리 P. 1.2. ∥ 하류 1. 함평군 엄다면 학교리 P. 1.2. ∥하류 1. 광양군 다압면 신원리 2. 2. 나주군 다시면 신풍리 P. ∥ 2. 광양군 다압면 고사리 P. 1.2. 3. 나주군 문평면 용문리 2. ∥ ------------------------------------------------------------------------------------ *(주) P: 주민 감염율조사. 1: 제1 중간숙주조사. 2: 제2 중간 숙주조사. 상류는 전라북도와 전라남도의 경계선 이하에서 곡성군 곡성읍 상부와 섬진강의 지류인 보성강유역이 해당되며 중류지역은 섬진강과 보성강이 합류되는 곳에서부터 광양군 다압면의 상류지역으로 곡성군 일부와 구례군이 이에 해당되며 하류는 다압면이하로 광양군이 해당된다. 1. 주민의 감염율 : 상류 2개지역, 중하류 각 1개지역 등 4개지역에서 296명을 대상으로 조사하였던바 전체적으로 간디스토마 충란양성자는 21명(7.1%)인데 비해 요꼬가와흡충충란 양성자는 123명(41.6%)이었으며 지역별 간디스토마의 감염율은 상류 5.6%(7/124), 중류 7.4%(6/81), 하류 8.8%(8/91)이었으며 요꼬가와흡충은 상류29.0%(36/124), 중류 58.0%(47/81), 하류 44.0%(40/91)이었다. 요꼬가와흡충충란양성자의 경우 남자는 55.5%(81/146)로 여자의 28.0%(42/150)보다 약 2배 가량 높은 감염율을 보였다. 요꼬가와흡충충란은 전 연령층에서 검출되었으나 간디스토마는 19세이하에서는 검출되지 않았다. 한편 두 흡충의 혼합감염율은 5.7%(17/296)이었다. 2. 제 1 중간숙주 : 왜우렁은 중류지방에서만 채집되었으나 간디스토마셀카리아를 검출치 못하였고 다슬기는 모두 663개를 채집하여 검사한바 62개(9.4%)에서 요꼬가와흡충셀카리아를 검출하였다. 이를 지역별로 보면 상류 9.2%(39/427), 중류 4.8%(3/62), 하류 11.5%(20/174)의 양성율을 보였다. 3. 제 2 중간숙주 : 전지역에서 10종의 담수어 175마리를 포획하여 검사하였으나 간디스토마메타셀카리아는 검출치 못 하였다. 그러나 그중 은어에서는 35마리 전부에서 요꼬가와흡충메타셀카리아를 검출하였다. 이상의 성적으로 보아 영산강유역은 간디스토마의 만연지역이나 요꼬가와흡충의 만연은 볼 수 없었다. 그러나 섬진강유역은 요꼬가와흡충 및 간디스토마의 만연지역이라고 볼 수 있으나 이 지역의 간디스토마감염이 토착성인지는 더 추구되어야 할 과제라고 본다.

Fabrication of nanostructures of polyethylene glycol for applications to protein adsorption and cell adhesion

Kim, P,Kim, D H,Kim, B,Choi, S K,Lee, S H,Khademhosseini, A,Langer, R,Suh, K Y IOP Pub 2005 Nanotechnology Vol.16 No.10

<P>A simple method was developed to fabricate polyethylene glycol (PEG) nanostructures using capillary lithography mediated by ultraviolet (UV) exposure. Acrylate-containing PEG monomers, such as PEG dimethacrylate (PEG-DMA, MW = 330), were photo-cross-linked under UV exposure to generate patterned structures. In comparison to unpatterned PEG films, hydrophobicity of PEG nanostructure modified surfaces was significantly enhanced. This could be attributed to trapped air in the nanostructures as supported by water contact angle measurements. Proteins (fibronectin, immunoglobulin, and albumin) and cells (fibroblasts and P19 EC cells) were examined on the modified surfaces to test for the level of protein adsorption and cell adhesion. It was found that proteins and cells preferred to adhere on nanostructured PEG surfaces in comparison to unpatterned PEG films; however, this level of adhesion was significantly lower than that of glass controls. These results suggest that capillary lithography can be used to fabricate PEG nanostructures capable of modifying protein and cell adhesive properties of surfaces.</P>

Comparison of helper component-protease RNA silencing suppression activity, subcellular localization, and aggregation of three Korean isolates of Turnip mosaic virus

Han, J. Y.,Chung, J.,Kim, J.,Seo, E. Y.,Kilcrease, J. P.,Bauchan, G. R.,Lim, S.,Hammond, J.,Lim, H. S. Springer Science + Business Media 2016 Virus genes Vol.52 No.4

<P>In 2014, we performed a nationwide survey in Korean radish fields to investigate the distribution and variability of Turnip mosaic virus (TuMV). Brassica rapa ssp. pekinensis sap-inoculated with three isolates of TuMV from infected radish tissue showed different symptom severities, whereas symptoms in Raphanus sativus were similar for each isolate. The helper component-protease (HC-Pro) genes of each isolate were sequenced, and phylogenetic analysis showed that the three Korean isolates were clustered into the basal-BR group. The HC-Pro proteins of these isolates were tested for their RNA silencing suppressor (VSR) activity and subcellular localization in Nicotiana benthamiana. A VSR assay by co-agroinfiltration of HC-Pro with soluble-modified GFP (smGFP) showed that HC-Pro of isolate R007 and R041 showed stronger VSR activity than R065. The HC-Pros showed 98.25 % amino acid identity, and weak VSR isolate (R065) has a single variant residue in the C-terminal domain associated with protease activity and self-interaction compared to isolates with strong VSR activity. Formation of large subcellular aggregates of GFP: HC-Pro fusion proteins in N. benthamiana was only observed for HC-Pro from isolates with strong VSR activity, suggesting that R065 'weak' HC-Pro may have diminished self-association; substitution of the variant C-terminal residue largely reversed the HC-Pro aggregation and silencing suppressor characteristics. The lack of correlation between VSR efficiency and induction of systemic necrosis (SN) suggests that differences in viral accumulation due to HC-Pro are not responsible for SN.</P>