Hedgehog signalling regulates liver sinusoidal endothelial cell capillarisation
- Guanhua Xie1,
- Steve S Choi1,2,
- Wing-Kin Syn1,3,
- Gregory A Michelotti1,
- Marzena Swiderska1,
- Gamze Karaca1,
- Isaac S Chan1,
- Yuping Chen1,
- Anna Mae Diehl1
- 1Division of Gastroenterology, Duke University Medical Center, Durham, North Carolina, USA
- 2Section of Gastroenterology, Department of Medicine, Durham Veteran Affairs Medical Center, Durham, North Carolina, USA
- 3Section of Regeneration and Repair, Institute of Hepatology, London, UK
- Correspondence to Professor Anna Mae Diehl, Division of Gastroenterology Duke University Snyderman Building (GSRB-1) 595 LaSalle Street, Suite 1073 Durham, NC, 27710, USA;
Contributors GX designed and performed experiments, analysed data and wrote the manuscript; SSC, WKS and GAM designed and performed experiments; MS, GK, ISC and YC performed experiments; AMD designed experiments, supervised research, analysed data and wrote the manuscript.
- Accepted 13 January 2012
- Published Online First 23 February 2012
Objective Vascular remodelling during liver damage involves loss of healthy liver sinusoidal endothelial cell (LSEC) phenotype via capillarisation. Hedgehog (Hh) signalling regulates vascular development and increases during liver injury. This study therefore examined its role in capillarisation.
Design Primary LSEC were cultured for 5 days to induce capillarisation. Pharmacological, antibody-mediated and genetic approaches were used to manipulate Hh signalling. Effects on mRNA and protein expression of Hh-regulated genes and capillarisation markers were evaluated by quantitative reverse transcription PCR and immunoblot. Changes in LSEC function were assessed by migration and tube forming assay, and gain/loss of fenestrae was examined by electron microscopy. Mice with acute or chronic liver injury were treated with Hh inhibitors; effects on capillarisation were assessed by immunohistochemistry.
Results Freshly isolated LSEC expressed Hh ligands, Hh receptors and Hh ligand antagonist Hhip. Capillarisation was accompanied by repression of Hhip and increased expression of Hh-regulated genes. Treatment with Hh agonist further induced expression of Hh ligands and Hh-regulated genes, and upregulated capillarisation-associated genes; whereas Hh signalling antagonist or Hh ligand neutralising antibody each repressed expression of Hh target genes and capillarisation markers. LSEC isolated from SmoloxP/loxP transgenic mice that had been infected with adenovirus expressing Cre-recombinase to delete Smoothened showed over 75% knockdown of Smoothened. During culture, Smoothened-deficient LSEC had inhibited Hh signalling, less induction of capillarisation-associated genes and retention of fenestrae. In mice with injured livers, inhibiting Hh signalling prevented capillarisation.
Conclusions LSEC produce and respond to Hh ligands, and use Hh signalling to regulate complex phenotypic changes that occur during capillarisation.
- Alcoholic liver disease
- basic sciences
- carcinogen metabolism
- cell biology
- cell signalling
- fatty liver
- hepatic stellate cell
- hepatocellular carcinoma
- liver immunology
- liver regeneration
- molecular mechanisms
- non-alcoholic steatohepatitis
Funding This work was supported by National Institutes of Health grant RO1 DK077794 (AMD).
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.