The CD47-binding peptide of thrombospondin-1 induces defenestration of liver sinusoidal endothelial cells

Authors

  • Lakshmi Venkatraman,

    1. Mechanobiology Institute, National University of Singapore, Singapore
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  • Lisa Tucker-Kellogg

    Corresponding author
    1. Department of Dermatology, School of Medicine, State University of New York at Stony Brook, New York, NY, USA
    2. Singapore-MIT Alliance, National University of Singapore, Singapore
    • Mechanobiology Institute, National University of Singapore, Singapore
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Errata

This article is corrected by:

  1. Errata: Corrigendum Volume 34, Issue 4, 647, Article first published online: 29 December 2013

Correspondence

Dr Lisa Tucker-Kellogg Mechanobiology Institute, 5A Engineering Drive 1, National University of Singapore, 117411 Singapore

Tel: +65 6516 2865

Fax: +65 6872 6123

e-mail: lisaTK@nus.edu.sg

Abstract

Background & Aims

A fenestrated phenotype is characteristic of liver sinusoidal endothelial cells (LSECs), but liver sinusoids become defenestrated during fibrosis and other liver diseases. Thrombospondin-1 (TSP1) is a matrix glycoprotein with pro-fibrotic effects, and the CD47-binding fragment of TSP1 also has anti-angiogenic effects in endothelial cells. We hypothesized that the CD47-binding fragment of TSP1 could induce defenestration in LSECs through the Rho-Rho kinase (ROCK)-myosin pathway.

Methods

Freshly isolated rat LSECs were treated with TSP1 or CD47-binding peptides of TSP1. LSEC fenestration was assessed with scanning electron microscopy, and myosin phosphorylation was assessed with immuno-fluorescence.

Results

Treating LSECs with TSP1 caused a dose-dependent loss of fenestrae, and this effect could not be blocked by SB-431542, the TGF-β1 receptor inhibitor. A CD47-binding fragment of TSP1, p4N1, was able to induce defenestration, and a CD47-blocking antibody, B6H12, was able to suppress p4N1-induced defenestration. The p4N1 fragment also caused contraction of fenestra size, correlated with an increase in myosin activation. Pretreatment with Y-237642 (a ROCK inhibitor) prevented p4N1-induced myosin activation and fenestrae decrease. Simvastatin has also been shown to antagonize Rho-ROCK signalling, and we found that simvastatin pretreatment protected LSECs from p4N1-induced myosin activation and defenestration.

Conclusions

We conclude that CD47 signals through the Rho-ROCK-myosin pathway to induce defenestration in LSECs. In addition, our results show that simvastatin and Y-237642 have a beneficial impact on fenestration in vitro, providing an additional explanation for the efficacy of these compounds for regression of liver fibrosis.

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