Restricted Localization of the TNF Receptor CD120a to Lipid Rafts: A Novel Role for the Death Domain

Abstract

The TNF-α receptor, CD120a, has recently been shown to be localized to both plasma membrane lipid rafts and to the trans Golgi complex. Through a combination of both confocal microscopy and sucrose density gradient ultracentrifugation, we show that amino acid sequences located within the death domain (DD) of CD120a are both necessary and sufficient to promote the appropriate localization of the receptor to lipid rafts. Deletion of the DD (CD120a.Δ321-425) prevented the receptor from being targeted to lipid rafts and resulted in a uniform plasma membrane localization. A similar loss of raft localization was also observed following pairwise deletion of the six α-helices that comprise the DD. In all situations, the loss of the ability of CD120a to become localized to lipid rafts following mutagenesis was paralleled by a failure of the receptor to initiate apoptosis. Furthermore, introduction of the lpr mutation into CD120a (CD120a.L351N) also resulted in both a loss in the ability of the receptor to signal apoptosis and to be appropriately localized to rafts. In contrast to CD120a, CD120b, which lacks a DD, is mainly expressed in the bulk plasma membrane and to a lesser extent in lipid rafts, but is absent from the Golgi complex. However, a chimeric receptor in which the DD of CD120a was fused to the cytoplasmic domain of CD120b was predominantly localized to lipid rafts. Collectively, these findings suggest that in addition to its role in CD120a signaling, an appropriately folded and functionally active DD is required for the localization of the receptor to lipid rafts.

Tumor necrosis factor receptor I from patients with tumor necrosis factor receptor–associated periodic syndrome interacts with wild‐type tumor necrosis factor receptor I and induces ligand‐independent NF‐κB activation

“…The mechanisms by which cell surface expression of TNFRI may be controlled still remain unclear. Although TNFRI has been shown to accumulate predominantly in the trans-Golgi apparatus within the cell, this localization is dependent upon motifs within the cytoplasmic region of the receptor (22)(23)(24)(25). The TNFRI receptors used in this study were full length with tags at their carboxyl termini, since the presence of His tags at the amino terminus of TNFR may interfere with its PLAD-mediated self-assembly (26) and ligand binding.…”

Acute Alcohol Inhibits TNF-α Processing in Human Monocytes by Inhibiting TNF/TNF-α-Converting Enzyme Interactions in the Cell Membrane

“…Possibilities include changes in membrane fluidity (33) induced by EtOH (33), alterations in raft compartments, or perhaps abnormal ERK-mediated phosphorylation of TACE, which is critical for protein kinase Cregulated TrkA cleavage (34). Although there are no specific studies of yet examining TNF/TACE interactions in the context of membrane rafts, members of the TNF receptor superfamily, CD40 and CD120a (35,36), as well as ␣ secretases (37) have been localized to membrane rafts.…”

Role of membrane microdomain rafts in TNFR-mediated signal transduction

“…9 Similarly, a constitutive association of CD40 with rafts in dendritic cells, 10 and of TNFR1 in U937 and Hela cells 11,12 has been demonstrated. P75 NTR , one of the NGF receptors, has been shown to be specifically enriched in caveolae, a specialized membrane microdomain.…”

“…This model proposes that the relocalization of cytosolic adaptor molecules to lipid rafts induces signaling by allowing them to meet their targets, because of the highly increased probability to meet their receptor binding partners. In this context, the data reported by Cottin et al 12 are of particular interest: using a mutagenic approach, they show that the DD of TNFR1 is necessary for the localization of this receptor to the rafts, therefore suggesting a new role for the DD.…”