Daidzein suppresses pro-inflammatory chemokine Cxcl2 transcription in TNF-α-stimulated murine lung epithelial cells via depressing PARP-1 activity
Abstract
Hai-yan LI1, 3, Lang PAN2, Yue-shuang KE2, Enkhzaya BATNASAN2, Xiang-qun JIN1, Zhong-ying LIU1, *, Xue-qing BA2, *
1School of Pharmaceutical Science, Jilin University, Changchun 130021, China; 2Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China; 3Affiliated Hospital to Changchun University of Chinese Medicine, Changchun 130021, China
Aim: Daidzein (4',7-dihydroxyisoflavone) is an isoflavone exiting in many herbs that has shown anti-inflammation activity. The aim of this study was to investigate the mechanism underlying its anti-inflammatory action in murine lung epithelial cells.
Methods: C57BL/6 mice were intranasally exposed to TNF-α to induce lung inflammation. The mice were injected with daidzein (400 mg/kg, ip) before TNF-α challenge, and sacrificed 12 h after TNF-α challenge, and lung tissues were collected for analyisis. In in vitro studies, murine MLE-12 epithelial cells were treated with TNF-α (20 ng/mL). The expression of pro-inflammatory chemokine Cxcl2 mRNA and NF-κB transcriptional activity were examined using real-time PCR and a dual reporter assay. Protein poly-adenosine diphosphate-ribosylation (PARylation) was detecyed using Western blotting and immunoprecipitation assays.
Results: Pretreatment of the mice with daidzein markedly attenuated TNF-α-induced lung inflammation, and inhibited Cxcl2 expression in lung tissues. Furthermore, daidzein (10 μmol/L) prevented TNF-α-induced increases in Cxcl2 expression and activity and NF-κB transcriptional activity, and markedly inhibited TNF-α-induced protein PARylation in MLE-12 cells in vitro. In MLE-12 cells co-transfected with the PARP-1 expression plasmid and NF-κB-luc (or Cxcl2-luc) reporter plasmid, TNF-α markedly increased NF-κB (or Cxcl2) activation, which were significantly attenuated in the presence of daidzein (or the protein PARylation inhibitor PJ 34). PARP-1 activity assay showed that daidzein (10 μmol/L) reduced the activity of PARP-1 by ~75%.
Conclusion: The anti-inflammatory action of daidzein in murine lung epithelial cells seems to be mediated via a direct interaction with PARP-1, which inhibits RelA/p65 protein PARylation required for the transcriptional modulation of pro-inflammatory chemokines such as Cxcl2.
Keywords: daidzein; isoflavone; lung; inflammation; poly-adenosine diphosphate-ribosylation; PARP-1; chemokine; TNF-α; Cxcl2; NF-κB
This work was supported by grants from the National Natural Science Foundation of China (31371293), the Natural Science Foundation of Jilin Province in China (201015108) and the International Science-Technology Collaboration Foundation of Jilin Province in China (20120728). We thank Dr Patrick A ZWEIDLER-MCKAY (The University of Texas MD Anderson Cancer Center) for his generous gift of PARP-1 plasmid.
* To whom correspondence should be addressed.
E-mail baxq755@nenu.edu.cn (Xue-qing BA); liuzy@jlu.edu.cn (Zhong-ying LIU)
Received 2013-08-14 Accepted 2013-12-08
Keywords:
1School of Pharmaceutical Science, Jilin University, Changchun 130021, China; 2Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China; 3Affiliated Hospital to Changchun University of Chinese Medicine, Changchun 130021, China
Aim: Daidzein (4',7-dihydroxyisoflavone) is an isoflavone exiting in many herbs that has shown anti-inflammation activity. The aim of this study was to investigate the mechanism underlying its anti-inflammatory action in murine lung epithelial cells.
Methods: C57BL/6 mice were intranasally exposed to TNF-α to induce lung inflammation. The mice were injected with daidzein (400 mg/kg, ip) before TNF-α challenge, and sacrificed 12 h after TNF-α challenge, and lung tissues were collected for analyisis. In in vitro studies, murine MLE-12 epithelial cells were treated with TNF-α (20 ng/mL). The expression of pro-inflammatory chemokine Cxcl2 mRNA and NF-κB transcriptional activity were examined using real-time PCR and a dual reporter assay. Protein poly-adenosine diphosphate-ribosylation (PARylation) was detecyed using Western blotting and immunoprecipitation assays.
Results: Pretreatment of the mice with daidzein markedly attenuated TNF-α-induced lung inflammation, and inhibited Cxcl2 expression in lung tissues. Furthermore, daidzein (10 μmol/L) prevented TNF-α-induced increases in Cxcl2 expression and activity and NF-κB transcriptional activity, and markedly inhibited TNF-α-induced protein PARylation in MLE-12 cells in vitro. In MLE-12 cells co-transfected with the PARP-1 expression plasmid and NF-κB-luc (or Cxcl2-luc) reporter plasmid, TNF-α markedly increased NF-κB (or Cxcl2) activation, which were significantly attenuated in the presence of daidzein (or the protein PARylation inhibitor PJ 34). PARP-1 activity assay showed that daidzein (10 μmol/L) reduced the activity of PARP-1 by ~75%.
Conclusion: The anti-inflammatory action of daidzein in murine lung epithelial cells seems to be mediated via a direct interaction with PARP-1, which inhibits RelA/p65 protein PARylation required for the transcriptional modulation of pro-inflammatory chemokines such as Cxcl2.
Keywords: daidzein; isoflavone; lung; inflammation; poly-adenosine diphosphate-ribosylation; PARP-1; chemokine; TNF-α; Cxcl2; NF-κB
This work was supported by grants from the National Natural Science Foundation of China (31371293), the Natural Science Foundation of Jilin Province in China (201015108) and the International Science-Technology Collaboration Foundation of Jilin Province in China (20120728). We thank Dr Patrick A ZWEIDLER-MCKAY (The University of Texas MD Anderson Cancer Center) for his generous gift of PARP-1 plasmid.
* To whom correspondence should be addressed.
E-mail baxq755@nenu.edu.cn (Xue-qing BA); liuzy@jlu.edu.cn (Zhong-ying LIU)
Received 2013-08-14 Accepted 2013-12-08