医学部

sasaki jun

  (佐々木 潤)

Profile Information

Affiliation
School of Medicine Faculty of Medicine, Fujita Health University
Degree
農学博士

J-GLOBAL ID
200901013953042307
researchmap Member ID
1000289363

Research Areas

 1

Papers

 24
  • Takayuki Murata, Satoshi Komoto, Satoko Iwahori, Jun Sasaki, Hironori Nishitsuji, Terumitsu Hasebe, Kiyotaka Hoshinaga, Yukio Yuzawa
    Microbiology and Immunology, 65(1) 10-16, Dec 14, 2020  Peer-reviewed
  • Kumiko Ishikawa-Sasaki, Shigeo Nagashima, Koki Taniguchi, Jun Sasaki
    Journal of Virology, 92(8), Apr 1, 2018  
    Positive-strand RNA viruses, including picornaviruses, utilize cellular machinery for genome replication. Previously, we reported that each of the 2B, 2BC, 2C, 3A, and 3AB proteins of Aichi virus (AiV), a picornavirus, forms a complex with the Golgi apparatus protein ACBD3 and phosphatidylinositol 4-kinase IIIβ (PI4KB) at viral RNA replication sites (replication organelles [ROs]), enhancing PI4KB-dependent phosphatidylinositol 4-phosphate (PI4P) production. Here, we demonstrate AiV hijacking of the cellular cholesterol transport system involving oxysterol-binding protein (OSBP), a PI4P-binding cholesterol transfer protein. AiV RNA replication was inhibited by silencing cellular proteins known to be components of this pathway, OSBP, the ER membrane proteins VAPA and VAPB (VAP-A/B), the PI4P-phosphatase SAC1, and PItransfer protein β. OSBP, VAP-A/B, and SAC1 were present at RNA replication sites. We also found various previously unknown interactions among the AiV proteins (2B, 2BC, 2C, 3A, and 3AB), ACBD3, OSBP, VAP-A/B, and SAC1, and the interactions were suggested to be involved in recruiting the component proteins to AiV ROs. Importantly, the OSBP-2B interaction enabled PI4P-independent recruitment of OSBP to AiV ROs, indicating preferential recruitment of OSBP among PI4P-binding proteins. Protein-protein interaction-based OSBP recruitment has not been reported for other picornaviruses. Cholesterol was accumulated at AiV ROs, and inhibition of OSBPmediated cholesterol transfer impaired cholesterol accumulation and AiV RNA replication. Electron microscopy showed that AiV-induced vesicle-like structures were close to ER membranes. Altogether, we conclude that AiV directly recruits the cholesterol transport machinery through protein-protein interactions, resulting in formation of membrane contact sites between the ER and AiV ROs and cholesterol supply to the ROs.
  • Kumiko Ishikawa-Sasaki, Jun Sasaki, Koki Taniguchi
    JOURNAL OF VIROLOGY, 88(12) 6586-6598, Jun, 2014  
    Phosphatidylinositol 4-kinase III beta (PI4KB) is a host factor required for the replication of certain picornavirus genomes. We previously showed that nonstructural proteins 2B, 2BC, 2C, 3A, and 3AB of Aichi virus (AiV), a picornavirus, interact with the Golgi protein, acyl-coenzyme A binding domain containing 3 (ACBD3), which interacts with PI4KB. These five viral proteins, ACBD3, PI4KB, and the PI4KB product phosphatidylinositol 4-phosphate (PI4P) colocalize to the AiV RNA replication sites (J. Sasaki et al., EMBO J. 31: 754 -766, 2012). We here examined the roles of these viral and cellular molecules in the formation of AiV replication complexes. Immunofluorescence microscopy revealed that treatment of AiV polyprotein-expressing cells with a small interfering RNA targeting ACBD3 abolished colocalization of the viral 2B, 2C, and 3A proteins with PI4KB. A PI4KB-specific inhibitor also prevented their colocalization. Virus RNA replication increased the level of cellular PI4P without affecting that of PI4KB, and individual expression of 2B, 2BC, 2C, 3A, or 3AB stimulated PI4P generation. These results suggest that the viral protein/ACBD3/PI4KB complex plays an important role in forming the functional replication complex by enhancing PI4P synthesis. Of the viral proteins, 3A and 3AB were shown to stimulate the in vitro kinase activity of PI4KB through forming a 3A or 3AB/ACBD3/PI4KB complex, whereas the ACBD3-mediated PI4KB activation by 2B and 2C remains to be demonstrated.
  • Jun Sasaki, Kumiko Ishikawa, Minetaro Arita, Koki Taniguchi
    EMBO JOURNAL, 31(3) 754-766, Feb, 2012  
    Phosphatidylinositol 4-kinase III beta (PI4KB) is a host factor required for genome RNA replication of enteroviruses, small non-enveloped viruses belonging to the family Picornaviridae. Here, we demonstrated that PI4KB is also essential for genome replication of another picornavirus, Aichi virus (AiV), but is recruited to the genome replication sites by a different strategy from that utilized by enteroviruses. AiV non-structural proteins, 2B, 2BC, 2C, 3A, and 3AB, interacted with a Golgi protein, acylcoenzyme A binding domain containing 3 (ACBD3). Furthermore, we identified previously unknown interaction between ACBD3 and PI4KB, which provides a novel manner of Golgi recruitment of PI4KB. Knockdown of ACBD3 or PI4KB suppressed AiV RNA replication. The viral proteins, ACBD3, PI4KB, and phophatidylinositol-4-phosphate (PI4P) localized to the viral RNA replication sites. AiV replication and recruitment of PI4KB to the RNA replication sites were not affected by brefeldin A, in contrast to those in enterovirus infection. These results indicate that a viral protein/ACBD3/PI4KB complex is formed to synthesize PI4P at the AiV RNA replication sites and plays an essential role in viral RNA replication. The EMBO Journal (2012) 31, 754-766. doi: 10.1038/emboj.2011.429; Published online 29 November 2011
  • Jun Sasaki, Kumiko Ishikawa, Koki Taniguchi
    VIRUS RESEARCH, 163(2) 592-598, Feb, 2012  
    Picornavirus genomes are translated into a single large polyprotein, which is processed by virus-encoded proteases into individual functional proteins. 3C of all picornaviruses is a protease, and the leader (L) and 2A proteins of some picornaviruses are also involved in polyprotein processing. Aichi virus (AiV), which is associated with acute gastroenteritis in humans, is a member of the genus Kobuvirus of the family Picornaviridae. The AiV L and 2A proteins have already been shown to exhibit no protease activity. In this study, we investigated AiV polyprotein processing by 3C and 3CD using a cell-free translation system. 3C and 3CD were capable of processing the polyprotein in trans; 3C, however, cleaved the VP1/2A site inefficiently, while 3CD cleaved this site almost completely. Mammalian two-hybrid and coimmunoprecipitation assays showed an interaction between 2A and 3CD. Using a 3CD mutant and various 2A mutants of substrate proteins, we showed a clear correlation between the 2A-3CD interaction and the VP1/2A cleavage by 3CD. Thus, this study suggests that tight interaction of 3CD with the 2A region of a precursor protein is required for efficient cleavage at the VP1/2A site. (C) 2011 Elsevier B.V. All rights reserved.

Misc.

 7
  • Koki Taniguchi, Satoshi Komoto, Jun Sasaki, Masanori Kugita
    Uirusu. Journal of virology, 59 91-98, Jan 1, 2009  
    Rotavirus is the leading pathogen for acute gastroenteritis in mammals and birds. Although the reverse genetics system has been utilized in many viruses, the system using a helper virus was developed for rotavirus in 2006. As a step for antigenic analysis of VP4 antigen of rotavirus, we prepared an infectious rotavirus with a spike protein VP4 having an antigenic mosaic by substituting one of the cross-reactive neutralization epitopes of a simian strain SA-11 with the corresponding one of a human strain DS-1. The future improvement and application of the rotavirus reverse genetics were discussed in this review.
  • TANIGUCHI Koki, KOMOTO Satoshi, SASAKI Jun, KUGITA Masanori
    36(3) 141-148, Jul 31, 2008  
  • Jun Sasaki, Koki Taniguchi
    Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme, 52(10) 1133-1138, Aug 1, 2007  
  • Jun Sasaki
    Uirusu. Journal of virology, 57(1) 67-74, Jun 1, 2007  
    Aichi virus is a member of the Family Picornaviridae. This virus was first isolated in 1989 from a stool specimen from a patient with oyster-associated gastroenteritis in Aichi, Japan. We analyzed the function of the 5' terminal region of the genome and the leader protein in virus replication. The results indicate that both the 5' terminal region of the genome and the leader protein are involved in viral RNA replication and encapsidation.
  • MAENO Yoshimasa, TSUJI Takao, NAKAZAWA Shusuke, NAGASHIMA Shigeo, KUSUHARA Yasuhiro, SASAKI Jun, KANBARA Hiroji, TANIGUCHI Koki
    Medical entomology and zoology, 52, Apr 4, 2001  

Presentations

 3

Research Projects

 10

教育内容・方法の工夫(授業評価等を含む)

 1
  • 件名(英語)
    -
    終了年月日(英語)
    2013
    概要(英語)
    M2「ウイルス・寄生虫学」において、講義の時点では、なじみのうすい「ウイルス」という生物に対するイメージをしやすいような説明につとめた。