Elsevier

Journal of Hepatology

Volume 40, Issue 1, January 2004, Pages 14-23
Journal of Hepatology

Transcriptional reprogramming in murine liver defines the physiologic consequences of biliary obstruction

https://doi.org/10.1016/j.jhep.2003.09.025Get rights and content

Abstract

Background/Aims: While the metabolic and histological responses to cholestasis are recognized, the consequences of impaired biliary flow on liver gene expression are largely undefined. We hypothesized that biliary obstruction results in transcriptional reprogramming that dictates the physiologic response.

Methods: We determined global gene expression in murine livers 1–21 days following bile duct ligation. Total hepatic cRNA from experimental and sham mice was hybridized to Affymetrix gene chips. Gene expression data was analyzed by GeneSpring® software and validated by Northern analysis.

Results: We found 92 genes over-expressed ≥2-fold at one or more time points following bile duct ligation. Functional classification of these genes revealed the activation of three main biological processes in a sequential and time-restricted fashion. At day 1, genes involved in sterol metabolism were uniquely over-expressed, including HMG-CoA reductase, the rate-limiting enzyme of cholesterol biosynthesis. This was followed by an increased expression of growth-promoting genes at day 7, the time point coinciding with peak cholangiocyte proliferation. In later phases (days 14–21), the liver over-expressed genes encoding structural proteins and proteases.

Conclusions: Transcriptional reprogramming in the liver following biliary obstruction favors the activation of genes regulating metabolism, cell proliferation, and matrix remodeling in a time-restricted and sequential fashion.

Introduction

The timely activation of key physiologic processes is central to the reparative response of the liver to acute or chronic injuries. In chronic cholestasis, activation of non-parenchymal cells and progressive fibrosis dominate the response [1], while low-grade cellular proliferation is maintained to supply the critical cellular mass necessary to meet metabolic demands. In contrast, the response following an acute liver injury emphasizes cellular proliferation as the physiologic priority [2], [3]. The impaired hepatocyte proliferation and decreased survival following partial hepatectomy in mice lacking interleukin-6, tumor necrosis factor receptor, inducible nitric oxide synthase, and/or CCAAT enhancer-binding protein-β [4], [5], [6], [7] illustrate the genetic control of this response.

Similarly, cholestasis induces adaptive changes in hepatic gene expression, with an emphasis on maintaining intracellular homeostasis rather than restoring liver mass. For example, coordinate changes in the expression of genes encoding the sinusoidal sodium taurocholate cotransporter (NTCP), the canalicular organic cation transporter Mdr1, and cholesterol 7-α-hydroxylase minimize the accumulation of toxic bile acids within hepatocytes by decreasing both uptake and de novo synthesis [8], [9], [10]. In order to more broadly define the consequences of cholestasis on liver gene expression, we carried out a large-scale analysis of hepatic gene expression following bile duct ligation (BDL). We hypothesized that biliary obstruction results in transcriptional reprogramming that dictates the physiologic response. We found that following biliary obstruction there is a time-restricted and sequential pattern of gene activation, beginning with induction of cholesterol metabolism, followed by activation of cellular proliferation, and finally by production and remodeling of the structural matrix.

Section snippets

Bile duct ligation

BDL was performed in 4–6 week-old female mice of mixed genetic background (C57Bl/6-SJL-Swiss Black). Using anesthesia with a 2% isofluorane/98% room air mixture, an abdominal incision was followed by retraction of the duodenum and dissection of the bile duct toward the hepatic hilum, where it was completely transected between two sutures. The abdominal wall was then sutured, and the mouse was allowed to awake from anesthesia. To demonstrate complete occlusion of the biliary system, we injected

Reprogramming of liver gene expression following biliary obstruction

Gene expression analysis revealed 92 transcripts expressed ≥2-fold above controls at one or more time points following BDL. Grouping of these genes based on level of expression and time after BDL identified two distinct patterns (Fig. 1A; Table 2). The first was a unique overexpression of 27% of genes at specific time points following BDL, with baseline levels of expression at all other time points. In the second, 73% of transcripts were highly sensitive to biliary obstruction and displayed

Discussion

Our large-scale analysis of liver gene expression following biliary obstruction demonstrates an organized pattern of gene activation that reflects the timely initiation of specific physiologic processes in response to impaired bile flow. Although there was a dominant activation of metabolic genes at all phases, involvement of specific pathways varied according to the duration of obstruction. Overall, the reprogramming in gene expression occurred in a time-restricted and sequential fashion

Acknowledgements

The authors thank Bruce Aronow for tutorial in use of gene expression software and preliminary analysis of gene expression profiles, and Drs Dong-Yi Zhang and Pranavkumar Shivakumar for technical assistance and support for real-time PCR. We also thank Drs William F. Balistreri, John C. Bucuvalas, and James E. Heubi for insightful review of the manuscript. This work was supported in part by the NIH- R01-DK064008 grant and the Translational Research Initiative of Cincinnati Children's Hospital

References (43)

  • N Tsukada et al.

    The structure and organization of the bile canalicular cytoskeleton with special reference to actin and actin-binding proteins

    Hepatology

    (1995)
  • I Tatsuno et al.

    Geranylgeranylpyrophosphate, a metabolite of mevalonate, regulates the cell cycle progression and DNA synthesis in human lymphocytes

    Biochem Biophys Res Commun

    (1997)
  • N Kelley-Loughnane et al.

    Independent and overlapping transcriptional activation during liver development and regeneration in mice

    Hepatology

    (2002)
  • L Polimeno et al.

    Cell proliferation and oncogene expression after bile duct ligation in the rat: evidence of a specific growth effect on bile duct cells

    Hepatology

    (1995)
  • M.T Levy et al.

    Oncostatin M: a cytokine upregulated in human cirrhosis, increases collagen production by human hepatic stellate cells

    J Hepatol

    (2000)
  • L Krahenbuhl et al.

    Progressive decrease in tissue glycogen content in rats with long-term cholestasis

    Hepatology

    (1996)
  • R.C Benyon et al.

    Mechanisms of hepatic fibrosis

    J Pediatr Gastroenterol Nutr

    (1998)
  • N Fausto et al.

    Liver regeneration. 2. Role of growth factors and cytokines in hepatic regeneration

    Faseb J

    (1995)
  • G.K Michalopoulos et al.

    Liver regeneration

    Science

    (1997)
  • D.E Cressman et al.

    Liver failure and defective hepatocyte regeneration in interleukin-6-deficient mice

    Science

    (1996)
  • Y Yamada et al.

    Initiation of liver growth by tumor necrosis factor: deficient liver regeneration in mice lacking type I tumor necrosis factor receptor

    Proc Natl Acad Sci USA

    (1997)
  • Cited by (20)

    • Splanchnic Th<inf>2</inf> and Th<inf>1</inf> cytokine redistribution in microsurgical cholestatic rats

      2010, Journal of Surgical Research
      Citation Excerpt :

      The response of the murine liver to biliary obstructive injury implies its transcriptional reprogramming favoring the activation of gene regulating metabolism, cell proliferation, and matrix remodeling in a time-restricted and sequential fashion [64]. This evolution results in deranged hepatic energy metabolism, as well as in a loss of antioxidant power by the liver [23, 24, 44, 64]. Both factors could progressively aggravate the inflammatory response evolution in the gastrointestinal tract, and induce high long-term mortality through the development of sepsis related complications.

    • Cystamine restores GSTA3 levels in Vanin-1 null mice

      2008, Free Radical Biology and Medicine
    • Transcription factor GATA6: A novel marker and putative inducer of ductal metaplasia in biliary atresia

      2018, American Journal of Physiology - Gastrointestinal and Liver Physiology
    • Chronic inflammation of biliary atresia

      2013, Chronic Inflammation: Causes, Treatment Options and Role in Disease
    View all citing articles on Scopus
    View full text