TRAIL Induces Nuclear Translocation and Chromatin Localization of TRAIL Death Receptors

Abstract

Binding of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to the plasma membrane TRAIL-R1/-R2 selectively kills tumor cells. This discovery led to evaluation of TRAIL-R1/-R2 as targets for anti-cancer therapy, yet the corresponding clinical trials were disappointing. Meanwhile, it emerged that many cancer cells are TRAIL-resistant and that TRAIL-R1/-R2-triggering may lead to tumor-promoting effects. Intriguingly, recent studies uncovered specific functions of long ignored intracellular TRAIL-R1/-R2, with tumor-promoting functions of nuclear (n)TRAIL-R2 as the regulator of let-7-maturation. As nuclear trafficking of TRAIL-Rs is not well understood, we addressed this issue in our present study. Cell surface biotinylation and tracking of biotinylated proteins in intracellular compartments revealed that nTRAIL-Rs originate from the plasma membrane. Nuclear TRAIL-Rs-trafficking is a fast process, requiring clathrin-dependent endocytosis and it is TRAIL-dependent. Immunoprecipitation and immunofluorescence approaches revealed an interaction of nTRAIL-R2 with the nucleo-cytoplasmic shuttle protein Exportin-1/CRM-1. Mutation of a putative nuclear export sequence (NES) in TRAIL-R2 or the inhibition of CRM-1 by Leptomycin-B resulted in the nuclear accumulation of TRAIL-R2. In addition, TRAIL-R1 and TRAIL-R2 constitutively localize to chromatin, which is strongly enhanced by TRAIL-treatment. Our data highlight the novel role for surface-activated TRAIL-Rs by direct trafficking and signaling into the nucleus, a previously unknown signaling principle for cell surface receptors that belong to the TNF-superfamily.

TRAIL-receptor 2—a novel negative regulator of p53

“…This paradigm shift moved intracellular TRAIL receptors into the focus of current studies and resulted in the discovery of first cytoplasmic and nuclear functions of these receptors with nTRAIL-R2 being a regulator of miRNA maturation [ 18 , 40 – 42 ]. The subsequently reported presence of TRAIL death receptors in the chromatin fraction, signalized that this is just the beginning of the story about the nuclear functions of these proteins [ 12 ]. In agreement, here we propose that nTRAIL-R2 acts as an inhibitor of the tumor suppressor protein p53.…”

“…All these TRAIL-R-functions are linked to their presence at the plasma membrane. Recently, it was shown that the TRAIL-Rs can translocate from the plasma membrane to the nucleus in TRAIL-dependent manner [ 12 ]. Interestingly, TRAIL-R1 and TRAIL-R2 are commonly overexpressed in cancer cells, but are frequently detected intracellularly and high intracellular abundance, especially of TRAIL-R2, was correlated with poor patient prognosis [ 13 ].…”

“…As such, it was described that nuclear TRAIL-R2 negatively regulates the maturation of miRNA let-7 via interaction with the microprocessor complex and enhances tumor cell malignancy [ 18 ]. Intriguingly, both nuclear TRAIL-R1 (nTRAIL-R1) and nTRAIL-R2 are associated with chromatin suggesting their role in regulating gene expression [ 12 ].…”

Regulation of Death Receptor Signaling by S-Palmitoylation and Detergent-Resistant Membrane Micro Domains—Greasing the Gears of Extrinsic Cell Death Induction, Survival, and Inflammation

“…In all cases, nuclear TRAIL-R localization has been reported to promote cell survival [ 200 ]. Recently, Mert and colleagues showed that both receptors can be endocytosed upon TRAIL binding by CME from the PM and undergo trafficking to the nucleus [ 201 ]. However, it is not clear how full-length DR4 and DR5 can enter the nucleus and exert their function in this compartment.…”

Intracranial Delivery of Synthetic mRNA Using Common Transfection Reagent

“…Its protein product can speci cally kill cancer cells without harming normal cells [9][10][11][12][13]. Owing to its tumor cell-speci c killing effect, TRAIL has been widely used in preclinical and clinical studies [12,[14][15][16][17][18][19][20][21][22][23]]. In the current study, we used synthetic TRAIL-mRNA as an example to verify whether this method of intracranial injection can be applied for the treatment of GBM.…”