title: In vivo imaging of antioxidant response element activity during liver regeneration after partial hepatectomy.
abstract: The nuclear factor-erythroid 2-related factor 2 (Nrf2) -antioxidant response element (ARE) pathway is important for the regulation of antioxidative stress response and detoxification. To activate the expression of its target genes, such as heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase (quinone) 1 (NQO1), Nrf2 binds to the ARE within the promoter region of these genes. Partial hepatectomy and consecutive liver regeneration lead to oxidative stress with activation of the Nrf2-ARE pathway. The aim of this study was to investigate ARE activity in vivo during liver regeneration after partial hepatectomy.
  
  
  
  Transgenic ARE-luc mice were used. In these mice, the luciferase reporter gene is under the control of an ARE promoter element. Following 2/3 partial hepatectomy (PHx), mice underwent in vivo bioluminescence imaging up until the ninth postoperative day. In addition, liver tissue was analyzed by immunohistochemistry (Nrf2 and HO-1), quantitative reverse transcription-PCR (HO-1 and NQO1) and in vitro luminescence assays.
  
  
  
  Bioluminescence imaging revealed a significant increase in Nrf2-ARE activity after PHx. The signal maximum was recorded on the third day after PHx. Seven days postoperatively, the signal almost reached baseline levels. In immunohistochemistry, significantly more hepatocytes were positive for Nrf2 and HO-1 on the third postoperative day compared with baseline levels. The mRNA expression of HO-1 and NQO1 were significantly increased on day 3 as measured by qRT-PCR.
  
  
  
  This study demonstrated the time-dependent activation of the Nrf2-ARE system during liver regeneration in vivo. The transgenic ARE-luc mouse provided a convenient model for studying Nrf2-mediated gene expression noninvasively and may facilitate further experiments with therapeutic modulation of the antioxidative stress response.
authors.affiliation: Department of General, Visceral, and Transplantation Surgery, RWTH Aachen University Hospital, Aachen, Germany. Electronic address: palizai@ukaachen.de.
authors.forename: Patrick Hamid
authors.initials: PH
authors.lastname: Alizai
authors.affiliation: Department of General, Visceral, and Transplantation Surgery, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Lea
authors.initials: L
authors.lastname: Bertram
authors.affiliation: Department of Anatomy and Cell Biology, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Athanassios
authors.initials: A
authors.lastname: Fragoulis
authors.affiliation: Department of Anatomy and Cell Biology, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Wruck
authors.affiliation: Department of Gastroenterology and Metabolic Disorders, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Daniela C
authors.initials: DC
authors.lastname: Kroy
authors.affiliation: Department of General, Visceral, and Transplantation Surgery, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Klinge
authors.affiliation: Department of General, Visceral, and Transplantation Surgery, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Ulf P
authors.initials: UP
authors.lastname: Neumann
authors.affiliation: Department of General, Visceral, and Transplantation Surgery, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Schmeding
mesh_terms: D000818:Animals; D061745:Antioxidant Response Elements / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D006498:Hepatectomy; D007150:Immunohistochemistry; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D011184:Postoperative Period; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse; D016660:NAD(P)H Dehydrogenase (Quinone); C491732:Nqo1 protein, mouse
keywords: Antioxidant response element; Bioluminescence; HO-1; In vivo imaging; Liver regeneration; Nrf2; Oxidative stress; Partial hepatectomy