TRAIL Induces Nuclear Translocation and Chromatin Localization of TRAIL Death Receptors.

Ufuk Mert,Pierre Teichmann,Johannes Lemke,Elisabeth Scharff,Verena Haselmann,Alshaimaa Adawy,Silvia Von Karstedt,Anna Trauzold,Jürgen Fritsch,Anna Willms,Cynthia Colmorgen

doi:10.3390/cancers11081167

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.

Highlights

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) binds to four plasma membrane-expressed receptors tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-R1-R4
Plasma Membrane TRAIL-R1 and TRAIL-R2 Translocate to the Nucleus in a TRAIL-Dependent Manner
We hypothesized that the internalization of TRAIL-R1/-R2 and their nuclear translocation represents a constitutive and very rapid process since cytoplasmic and nuclear fractions that were free of biotinylated plasma membrane-derived receptors could not be obtained even at very short time points

Summary

Introduction

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) binds to four plasma membrane-expressed receptors TRAIL-R1-R4. Two of these receptors, TRAIL-R1/DR4 [1] and TRAIL-R2/DR5/TRICK/Killer [2,3], contain a so-called death domain (DD) and they are capable of inducing apoptosis or necroptosis in response to ligand binding [4,5,6,7]. TRAIL gained special attention due to its ability to induce cell death preferentially in tumor cells, while sparing normal cells [13,14]. This led to the development of TRAIL formulations and agonistic anti-TRAIL-R1/-R2 antibodies, which were tested in clinical trials for the treatment of different malignancies (reviewed in [15]). A TRAIL-induced secretome impacts the tumor microenvironment and further enhances the promotion of malignancy [25]

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