ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2014, Vol. 45 ›› Issue (11): 1866-1873.doi: 10.11843/j.issn.0366-6964.2014.11.018

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Streptococcus suis Serotype 2 Protein AroC Induces Toll-Like Receptor 4-Dependent Inflammatory Responses in RAW264.7 via p38MAPK and NF-κB Signaling

LIU Jian-tao,ZHANG Qiang,SONG Ya-jing,YAN Shu-xian,YU Jun-ping,ZHANG An-ding,JIN Mei-lin*   

  1. (National Key Laboratory of Agricultural Microbiology,Huazhong Agricultural University,Wuhan 430070,China)
  • Received:2014-04-08 Online:2014-11-23 Published:2014-11-23

Abstract:

Streptococcus suis is an important swine pathogen and an emerging zoonotic agent of septicemia and meningitis.The purpose of this study was to express and purify protein aroC of S.suis and to analyse its ability of stimulating RAW264.7 cells inflammatory factor expression and to explain its molecular mechanism.aroC gene was amplified by using the genome of SC19 and cloned into the expression plasmid pET28a(+).The inclution bodies of recombinant aroC were expressed in E.coli of BL21.It was dissolved with 8 mol•L -1 urea (50 mmol•L-1 Tris,pH 8.0),and then renaturalized by dialysis and purified.The recombinant LPS-free and germ free protein was further tested on the stimulation of cytokine of RAW264.7 by real-time PCR.In order to analyse its molecular mechanism of stimulating macrophage inflammatory factors,we pre-treated the cell cultures with specific ERK1/2,JNK,NF-κB and P38 pathway inhibitors and antibodies of TLR2 and TLR4.Results showed that the aroC protein was renaturalized and purified successfully.It has a strong stimulating on secretion of cytokines of RAW264.7,and pre-treatment of the cell cultures with specific NF-κB pathway inhibitors and TLR4 antibody significantly decreased aroC induced TNF-α and IL-1β mRNA production,and pre-treatment of the cell cultures with specific p38 pathway inhibitors significantly decreased aroC induced TNF-α mRNA production.The results presented here demonstrate that protein aroC of S.suis serotype 2 induces Toll-like receptor 4-dependent inflammatory responses in RAW264.7 via p38MAPK and NF-κB Signaling.

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