The Molecular Mechanism of Leptin Secretion and Expression Induced by Aristolochic Acid in Kidney Fibroblast

被引:21
作者
Lin, Tsung-Chieh [1 ]
Lee, Tien-Chiang [2 ]
Hsu, Shih-Lan [2 ]
Yang, Chung-Shi [1 ,3 ]
机构
[1] Natl Def Med Ctr, Grad Inst Life Sci, Taipei, Taiwan
[2] Taichung Vet Gen Hosp, Dept Educ & Res, Taichung, Taiwan
[3] Ctr Nanomed Res, Natl Hlth Res Inst, Miaoli, Taiwan
来源
PLOS ONE | 2011年 / 6卷 / 02期
关键词
BINDING PROTEIN-ALPHA; MOUSE OBESE GENE; TGF-BETA; RAT ADIPOCYTES; IN-VIVO; OB GENE; RECEPTOR; INSULIN; ACTIVATION; CELLS;
D O I
10.1371/journal.pone.0016654
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Background: Leptin is a peptide hormone playing pivotal role in regulating food intake and energy expenditure. Growing evidence has suggested the pro-inflammatory and fibrogenic properties of leptin. In addition, patients with renal fibrosis have higher level of plasma leptin, which was due to the increased leptin production. Aristolochic acid (AA) is a botanical toxin characterized to associate with the development of renal fibrosis including tubulointerstitial fibrosis. However, whether leptin is upregulated to participate in AA-induced kidney fibrosis remain completely unknown. Methodology/Principal Findings: In this study, leptin expression was increased by sublethal dose of AA in kidney fibroblast NRK49f determined by enzyme-linked immunosorbent assay and Western blot. Data from real-time reverse transcriptase-polymerase chain reaction revealed that leptin was upregulated by AA at transcriptional level. DNA binding activity of CCAAT enhancer binding protein alpha (C/EBP alpha), one of the transcription factors for leptin gene, was enhanced in DNA affinity precipitation assay and chromatin immunoprecipitation experiments. Knockdown of C/EBP alpha expression by small interfering RNA markedly reduced AA-induced leptin expression. Moreover, AA promoted Akt interaction with p-PDK1, and increased phosphorylated activation of Akt. Akt knockdown, and inhibition of Akt signaling by LY294002 and mTOR inhibitor rapamycin reduced leptin expression. Furthermore, treatment of LY294002 or rapamycin significantly suppressed AAinduced C/EBP alpha DNA-binding activity. These results suggest that Akt and C/EBP alpha activation were involved in AA-regulated leptin expression. Conclusions/Significance: Our findings demonstrate the first that AA could induce secretion and expression of fibrogenic leptin in kidney fibroblasts, which reveal potential involvement of leptin in the progression of kidney fibrosis in aristolochic acid nephropathy.
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页数:8
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