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

Alessio d'Alessio (1) , Bianca Esposito (1) , Claudia Giampietri (1) , Elio Ziparo (1) , Jordan S Pober (2) , Antonio Filippini (1)

1 DAHFMO - Department of Anatomy, Histology, Forensic Medicine and Orthopedic [Roma]
2 Department of Immunobiology

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.

Domaines: Biologie cellulaire

Alessio d'Alessio, Bianca Esposito, Claudia Giampietri, Elio Ziparo, Jordan S Pober, et al.. Plasma membrane microdomains regulate TACE-dependent TNFR1 shedding in human endothelial cells.. Journal of Cellular and Molecular Medicine, 2012, 16 (3), pp.627-36. ⟨10.1111/j.1582-4934.2011.01353.x⟩. ⟨pasteur-00966442⟩