P300-dependent STAT3 acetylation is necessary for angiotensin II-induced pro-fibrotic responses in renal tubular epithelial cells
Abstract
Jun NI1, Yang SHEN1, Zhen WANG1, De-cui SHAO1, Jia LIU1, Ya-li KONG1, Lan-jun FU2, Li ZHOU1, Hong XUE1, Yu HUANG3, Wei ZHANG1, Chen YU2, *, Li-min LU1, *
1Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai 200032, China; 2Department of Nephrology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China; 3School of Biomedical Sciences and Institute of Vascular Medicine, Chinese University of Hong Kong, Hong Kong, China
Aim: To explore the role of signal transducer and activator of transcription 3 (STAT3) signaling pathway, especially STAT3 acetylation, in angiotensin II (Ang II)-induced pro-fibrotic responses in renal tubular epithelial cells.
Methods: Rat renal tubular epithelial cell line (NRK-52E) was used. STAT3 acetylation, phosphorylation and Janus kinase 2 (Jak2) phosphorylation, as well as the expression of fibronectin, collagen IV, transforming growth factor-β1 (TGF-β1) and p300 were examined using Western blotting. The level and localization of STAT3 phosphorylation on Tyr705 were detected with fluorescence immunocytochemistry. The cells were transfected with a plasmid vector carrying p300 gene or siRNA targeting p300 to regulate p300 expression.
Results: Overexpression of p300 significantly increased STAT3 acetylation on Lys685, STAT3 phosphorylation on Tyr705, and the expression of TGF-β1, collagen IV and fibronectin in the cells. Treatment of the cells with Ang II (1 μmol/L) significantly increased STAT3 phosphorylation on Tyr705 through JAK2 activation, and dose-dependently increased the expression of fibronectin, collagen IV and TGF-β1. Pretreatment with curcumin, an inhibitor of JAK2 and p300, blocked Ang II-induced effects. Knockdown of p300 significantly decreased STAT3 acetylation on Lys685, and abolished Ang II-stimulated STAT3 phosphorylation on Tyr705, whereas pretreatment of the cells with C646, a selective inhibitor of p300, inhibited Ang II-induced STAT3 nuclear translocation and the expression of TGF-β1, collagen IV and fibronectin. Pretreatment of the cells with AG490, a JAK2 inhibitor, markedly inhibited Ang II-induced STAT3 phosphorylation on Tyr705 and fibronectin expression.
Conclusion: P300-dependent STAT3 acetylation is necessary for Ang II-induced STAT3 phosphorylation and the consequent pro-fibrotic responses in renal tubular epithelial cells in vitro.
Keywords: renal fibrosis; angiotensin II; renal tubular epithelial cells; STAT3; JAK2; extracellular matrix; p300; curcumin; C646; AG490
This research was financially supported by the National Natural Science Foundation of China to Li-min LU (No 81070577 and 81170636), Hong XUE (No 81000280), Wei ZHANG (No 81100531) and Chen YU (No 81070547).
* To whom correspondence should be addressed.
E-mail yuchen2001@hotmail.com (Chen YU); lulimin@shmu.edu.cn (Li-min LU)
Received 2014-03-28 Accepted 2014-05-20
Keywords:
1Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai 200032, China; 2Department of Nephrology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China; 3School of Biomedical Sciences and Institute of Vascular Medicine, Chinese University of Hong Kong, Hong Kong, China
Aim: To explore the role of signal transducer and activator of transcription 3 (STAT3) signaling pathway, especially STAT3 acetylation, in angiotensin II (Ang II)-induced pro-fibrotic responses in renal tubular epithelial cells.
Methods: Rat renal tubular epithelial cell line (NRK-52E) was used. STAT3 acetylation, phosphorylation and Janus kinase 2 (Jak2) phosphorylation, as well as the expression of fibronectin, collagen IV, transforming growth factor-β1 (TGF-β1) and p300 were examined using Western blotting. The level and localization of STAT3 phosphorylation on Tyr705 were detected with fluorescence immunocytochemistry. The cells were transfected with a plasmid vector carrying p300 gene or siRNA targeting p300 to regulate p300 expression.
Results: Overexpression of p300 significantly increased STAT3 acetylation on Lys685, STAT3 phosphorylation on Tyr705, and the expression of TGF-β1, collagen IV and fibronectin in the cells. Treatment of the cells with Ang II (1 μmol/L) significantly increased STAT3 phosphorylation on Tyr705 through JAK2 activation, and dose-dependently increased the expression of fibronectin, collagen IV and TGF-β1. Pretreatment with curcumin, an inhibitor of JAK2 and p300, blocked Ang II-induced effects. Knockdown of p300 significantly decreased STAT3 acetylation on Lys685, and abolished Ang II-stimulated STAT3 phosphorylation on Tyr705, whereas pretreatment of the cells with C646, a selective inhibitor of p300, inhibited Ang II-induced STAT3 nuclear translocation and the expression of TGF-β1, collagen IV and fibronectin. Pretreatment of the cells with AG490, a JAK2 inhibitor, markedly inhibited Ang II-induced STAT3 phosphorylation on Tyr705 and fibronectin expression.
Conclusion: P300-dependent STAT3 acetylation is necessary for Ang II-induced STAT3 phosphorylation and the consequent pro-fibrotic responses in renal tubular epithelial cells in vitro.
Keywords: renal fibrosis; angiotensin II; renal tubular epithelial cells; STAT3; JAK2; extracellular matrix; p300; curcumin; C646; AG490
This research was financially supported by the National Natural Science Foundation of China to Li-min LU (No 81070577 and 81170636), Hong XUE (No 81000280), Wei ZHANG (No 81100531) and Chen YU (No 81070547).
* To whom correspondence should be addressed.
E-mail yuchen2001@hotmail.com (Chen YU); lulimin@shmu.edu.cn (Li-min LU)
Received 2014-03-28 Accepted 2014-05-20