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Blood, 1 June 2006, Vol. 107, No. 11, pp. 4554-4562. Prepublished online as a Blood First Edition Paper on January 31, 2006; DOI 10.1182/blood-2005-09-3616. This Article Full Text Full Text (PDF) All Versions of this Article: 2005-09-3616v1 107/11/4554    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Shi, Y. Articles by Yamamura, H. Search for Related Content PubMed PubMed Citation Articles by Shi, Y. Articles by Yamamura, H. Related Collections Phagocytes Signal Transduction Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  PHAGOCYTES Protein-tyrosine kinase Syk is required for pathogen engulfment in complement-mediated phagocytosis Yuhong Shi, Yumi Tohyama, Tomomi Kadono, Jinsong He, S. M. Shahjahan Miah, Ryoichi Hazama, Chisato Tanaka, Kaoru Tohyama, and Hirohei Yamamura From the Department of Genome Sciences, Kobe University Graduate School of Medicine, Kobe; and Department of Laboratory Medicine and Clinical Pathology, Kawasaki Medical School, Kurashiki, Japan. The protein tyrosine kinase Syk plays a central role in Fc receptor–mediated phagocytosis in the adaptive immune system. We show here that Syk also plays an essential role in complement-mediated phagocytosis in innate immunity. Macrophage-like differentiated HL60 cells and C3bi-opsonized zymosan comprised the pathogen-phagocyte system. C3bi-opsonized zymosan particles promptly attached to the cells and were subsequently engulfed via complement receptor 3. During this process, Syk became tyrosine phosphorylated and accumulated around the nascent phagosomes. The transfer of Syk-siRNA or dominant-negative Syk (DN-Syk) into HL60 cells resulted in impaired phagocytosis. Quenching assays using fluorescent zymosan revealed that most of the attached zymosan particles were located inside parental HL60 cells, whereas few were ingested by the mutant cells. These data indicated that Syk is required for the engulfment of C3bi-opsonized zymosan. During C3bi-zymosan–induced phagocytosis, actin accumulation occurred around phagosomes and was followed by depolymerization, and further RhoA was activated together with tyrosine phosphorylation of Vav. These responses including the actin remodeling were suppressed in Syk-siRNA– or DN-Syk–expressing cells. Our results demonstrated that Syk plays an indispensable role in complement-mediated phagocytosis by regulating both actin dynamics and the RhoA activation pathway and that these functions of Syk lead to phagosome formation and pathogen engulfment. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: C. Lau, X. Wang, L. Song, M. North, S. Wiehler, D. Proud, and C.-W. Chow Syk Associates with Clathrin and Mediates Phosphatidylinositol 3-Kinase Activation during Human Rhinovirus Internalization J. Immunol., January 15, 2008; 180(2): 870 - 880. [Abstract] [Full Text] [PDF] K. A. Horan, K.-i. Watanabe, A. M. Kong, C. G. Bailey, J. E. J. Rasko, T. Sasaki, and C. A. Mitchell Regulation of Fc{gamma}R-stimulated phagocytosis by the 72-kDa inositol polyphosphate 5-phosphatase: SHIP1, but not the 72-kDa 5-phosphatase, regulates complement receptor 3 mediated phagocytosis by differential recruitment of these 5-phosphatases to the phagocytic cup Blood, December 15, 2007; 110(13): 4480 - 4491. [Abstract] [Full Text] [PDF]

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