Volume 16, Issue 3 pp. 626-635

Plasma membrane microdomains regulate TACE-dependent TNFR1 shedding in human endothelial cells

Alessio D.’Alessio

Corresponding Author

Alessio D.’Alessio

Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Anatomy, Histology, Forensic Medicine and Orthopedics–Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy

Dr. Alessio D’ALESSIO, Sapienza University of Rome, Section of Histology and Medical Embryology, Via A. Scarpa, 14. 00161, Rome, Italy. Tel.: +39-06-49766565 Fax: +39-06-4462854 E-mail: [email protected]Search for more papers by this author
Bianca Esposito

Bianca Esposito

Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Anatomy, Histology, Forensic Medicine and Orthopedics–Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy

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Claudia Giampietri

Claudia Giampietri

Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Anatomy, Histology, Forensic Medicine and Orthopedics–Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy

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Elio Ziparo

Elio Ziparo

Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Anatomy, Histology, Forensic Medicine and Orthopedics–Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy

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Jordan S. Pober

Jordan S. Pober

Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA

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Antonio Filippini

Antonio Filippini

Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Anatomy, Histology, Forensic Medicine and Orthopedics–Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy

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First published: 07 June 2011
Citations: 13

Abstract

Upon stimulation by histamine, human vascular endothelial cells (EC) shed a soluble form of tumour necrosis factor receptor 1 (sTNFR1) that binds up free TNF, dampening the inflammatory response. Shedding occurs through proteolytic cleavage of plasma membrane-expressed TNFR1 catalysed by TNF-α converting enzyme (TACE). Surface expressed TNFR1 on EC is largely sequestered into specific plasma membrane microdomains, the lipid rafts/caveolae. The purpose of this study was to determine the role of these domains in TACE-mediated TNFR1 shedding in response to histamine. Human umbilical vein endothelial cells derived EA.hy926 cells respond to histamine via H1 receptors to shed TNFR1. Both depletion of cholesterol by methyl-β-cyclodextrin and small interfering RNA knockdown of the scaffolding protein caveolin-1 (cav-1), treatments that disrupt caveolae, reduce histamine-induced shedding of membrane-bound TNFR1. Moreover, immunoblotting of discontinuous sucrose gradient fractions show that TACE, such as TNFR1, is present within low-density membrane fractions, concentrated within caveolae, in unstimulated EA.hy926 endothelial cells and co-immunoprecipitates with cav-1. Silencing of cav-1 reduces the levels of both TACE and TNFR1 protein and displaces TACE, from low-density membrane fractions where TNFR1 remains. In summary, we show that endothelial lipid rafts/caveolae co-localize TACE to surface expressed TNFR1, promoting efficient shedding of sTNFR1 in response to histamine.

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