title: Elevated hepatic multidrug resistance-associated protein 3/ATP-binding cassette subfamily C 3 expression in human obstructive cholestasis is mediated through tumor necrosis factor alpha and c-Jun NH2-terminal kinase/stress-activated protein kinase-signaling pathway.
abstract: Multidrug resistance-associated protein 3 (MRP3, ABC subfamily C [ABCC]3) plays an important role in protecting hepatocytes and other tissues by excreting an array of toxic organic anion conjugates, including bile salts. MRP3/ABCC3 expression is increased in the liver of some cholestatic patients, but the molecular mechanism of this up-regulation remains elusive. In this report, we assessed liver MRP3/ABCC3 expression in patients (n = 22) with obstructive cholestasis caused by gallstone blockage of bile ducts and noncholestatic patient controls (n = 22). MRP3/ABCC3 messenger RNA (mRNA) and protein expression were significantly increased by 3.4- and 4.6-fold, respectively, in these cholestatic patients where elevated plasma tumor necrosis factor alpha (TNFα) (4.7-fold; P < 0.01) and hepatic specificity protein 1 transcription factor (SP1) and liver receptor homolog 1 expression (3.1- and 2.1-fold at mRNA level, 3.5- and 2.5-fold at protein level, respectively) were also observed. The induction of hepatic MRP3/ABCC3 mRNA expression is significantly positively correlated with the level of plasma TNFα in these patients. In HepG2 cells, TNFα treatment induced SP1 and MRP3/ABCC3 expression in a dose- and time-dependent manner, where increased phosphorylation of c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) was also detected. These inductions were significantly reduced in the presence of the JNK inhibitor, SP600125. TNFα treatment enhanced HepG2 cell nuclear extract-binding activity to the MRP3/ABCC3 promoter, but was abolished by SP600125, as demonstrated by electrophoretic mobility shift assay (EMSA). An increase in nuclear protein-binding activity to the MRP3/ABCC3 promoter, consisting primarily of SP1, was also observed in liver samples from cholestatic patients, as assessed by supershift EMSA assays.
  
  
  CONCLUSIONS
  Our findings indicate that up-regulation of hepatic MRP3/ABCC3 expression in human obstructive cholestasis is likely triggered by TNFα, mediated by activation of JNK/SAPK and SP1.
authors: Institute of Gastroenterology, Chongqing, China.
authors: Jin
authors: J
authors: Chai
authors: Yu
authors: Y
authors: He
authors: Shi-Ying
authors: SY
authors: Cai
authors: Zhongyong
authors: Z
authors: Jiang
authors: Huaizhi
authors: H
authors: Wang
authors: Qiong
authors: Q
authors: Li
authors: Lei
authors: L
authors: Chen
authors: Zhihong
authors: Z
authors: Peng
authors: Xiaochong
authors: X
authors: He
authors: Xiaoping
authors: X
authors: Wu
authors: Tianli
authors: T
authors: Xiao
authors: Rongquan
authors: R
authors: Wang
authors: James L
authors: JL
authors: Boyer
authors: Wensheng
authors: W
authors: Chen
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D015153:Blotting, Western; D016022:Case-Control Studies; D002779:Cholestasis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018450:Disease Progression; D005260:Female; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D046509:Tissue Culture Techniques; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D048031:JNK Mitogen-Activated Protein Kinases; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D014409:Tumor Necrosis Factor-alpha; C114462:multidrug resistance-associated protein 3