Affiliation:
1. Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, Korea
2. Department of Life Sciences, Kyonggi University, Suwon, Korea
3. Department of Physiology and Division of Pathology, Michigan State University, East Lansing, MI, USA
Abstract
Objective Inflammation, a vital innate immune response against infection and injury, is mediated by macrophages. Spleen tyrosine kinase (Syk) regulates inflammatory responses in macrophages; however, its role and underlying mechanisms are uncertain. Materials and Methods In this study, overexpression and knockout (KO) cell preparations, phagocytosis analysis, confocal microscopy, reactive oxygen species (ROS) determination, mRNA analysis, and immunoprecipitation/western blotting analyses were used to investigate the role of Syk in phagocytosis and its underlying mechanisms in macrophages during inflammatory responses. Results Syk inhibition by Syk KO, Syk-specific small interfering RNA (siSyk), and a selective Syk inhibitor (piceatannol) significantly reduced the phagocytic activity of RAW264.7 cells. Syk inhibition also decreased cytochrome c generation by inhibiting ROS-generating enzymes in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, and ROS scavenging suppressed the phagocytic activity of RAW264.7 cells. LPS induced the tyrosine nitration (N-Tyr) of suppressor of cytokine signaling 1 (SOCS1) through Syk-induced ROS generation in RAW264.7 cells. On the other hand, ROS scavenging suppressed the N-Tyr of SOCS1 and phagocytosis. Moreover, SOCS1 overexpression decreased phagocytic activity, and SOCS1 inhibition increased the phagocytic activity of RAW264.7 cells. Conclusion These results suggest that Syk plays a critical role in the phagocytic activity of macrophages by inducing ROS generation and suppressing SOCS1 through SOCS1 nitration during inflammatory responses.
Funder
National Research Foundation of Korea
Subject
Pharmacology,Immunology,Immunology and Allergy,Pharmacology,Immunology,Immunology and Allergy
Cited by
1 articles.
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