Angiotensin II and Aldosterone stimulating NF-kappaB and AP-1 activation in hepatic fibrosis of rat.
OBJECTIVE
Intrahepatic renin-angiotensin-aldosterone system (RAAS) plays a key role in the fibrogenesis of liver. However, the signal transduction mechanism underlying effects of Angiotensin II (Ang II) and Aldosterone (Aldo) on Nuclear Factor-kappaB (NF-kappaB) and active protein-1 (AP-1) pathway in hepatic fibrogenesis remains to be fully elucidated. The present study aims to investigate the signal transduction mechanism underlying effects of Ang II and Aldo on NF-kappaB and AP-1 pathway during hepatic fibrogenesis.


METHODS
To assess the effect of AECI and Angiotensin II type 1 receptor (AT-1 receptor) blocker on NF-kappaB activity in liver, a model of fibrosis was performed in rat. In vitro, hepatic stellate cells (HSCs)-T6 cells were preincubated for 1 h or not with U0126, a specific inhibitor of extracellular signal regulated kinase (ERK), irbesartan, and N-acetylcysteine prior to exposure to Ang II or Aldo for the indicated times. DNA binding activity of NF-kappaB and AP-1 were analyzed by Electrophoretic mobility shift assay (EMSA). Western blot was used to detect expression of IkappaBalpha and Phospho-P42/44. RT-PCR was used to detect the expressions of tumor necrosis factor alpha (TNFalpha) mRNA and alpha1 (I) procollagen mRNA.


RESULTS
AECI and AT-1 receptor blocker exert anti-fibrosis effect through inhibiting NF-kappaB activation in liver. Ang II and Aldo increase HSCs NF-kappaB activity and NF-kappaB target gene-TNFalpha expression by inhibiting IkappaBalpha expression in a redox-sensitive manner. Ang II and Aldo also markedly increase HSCs AP-1 activity and AP-1 target gene-alpha1 (I) procollagen mRNA expression via ERK1/2 pathway in a redox-sensitive manner.


CONCLUSIONS
These results show that stimulation of NF-kappaB and AP-1 pathway mediate hepatic fibrogenesis induced by intrahepatic RAAS.
Li
Xu
X
Department of Emergency, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China. mylx99@163.com
Meng
Ying
Y
Wu
Pingsheng
P
Zhang
Zhenshu
Z
Yang
Xishan
X
D021581:Active Transport, Cell Nucleus; D000450:Aldosterone / Q000494:pharmacology*; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D008099:Liver / Q000378:metabolism*; D008106:Liver Cirrhosis, Experimental / Q000378:metabolism*; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D016328:NF-kappa B; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D000450:Aldosterone