DnaJ (hsp40) of Streptococcus pneumoniae is involved in bacterial virulence and elicits a strong natural immune reaction via PI3K/JNK

Publication date: March 2017
Source:Molecular Immunology, Volume 83
Author(s): Jin Cui, Chenyu Ma, Guo Ye, Yong Shi, Wenchun Xu, Liang Zhong, Jian Wang, Yibing Yin, Xuemei Zhang, Hong Wang
As a heat shock protein, DnaJ plays an important role in the pathogenesis of pneumococcal infection. However, how the virulence factor-DnaJ elicits host natural immunity still remains unclear. In this study, we investigated the effects of dnaJ deficiency in Streptococcus pneumoniae (S. pneumoniae) on bacterial virulence, and further explored the related molecular mechanisms in vivo and in vitro. By generating dnaJ deficient mutant (ΔdnaJ), the virulence and colonization were detected in murine pneumonia and sepsis models in vivo. Compared with wild-type parent strain, the abilities of rapid colonization and induction of inflammatory responses of ΔdnaJ in mouse lungs were significantly impaired. Simultaneously, recombinant DnaJ purified from E. coli expression system (rDnaJ) induced macrophage strain RAW264.7 to secrete IL-6 by activation of PI3K and JNK signal pathways, which were confirmed by the specific signaling inhibitors. In conclusion, DnaJ, a novel virulence protein, was essential for the virulence and colonization of S. pneumoniae and induced pro-inflammatory cytokine production in macrophages through PI3K/JNK.



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