EVER2 protein binds TRADD to promote TNF-α-induced apoptosis

G Gaud,M Favre,D Guillemot,F Vuillier,Y Jacob

doi:10.1038/cddis.2013.27

Abstract

EVER1 and 2 confer resistance to cutaneous oncogenic human papillomavirus infections by downregulating the activating protein 1 (AP-1) signaling pathway. Defects in their expression are associated with susceptibility to epidermodysplasia verruciformis, which is characterized by persistent β-HPV infection, tumor necrosis factor alpha (TNF-α) overproduction in keratinocytes and the development of skin cancers. TNF-α-induced apoptosis is a key defense strategy, preventing the persistence of the virus within cells, but the role of EVER proteins in this cell death mechanism triggered by extrinsic stimuli is unknown. We show here that EVER2 induces TNF-α- and TRAIL-dependant apoptosis. It interacts with the N-terminal domain of TRADD, impairs the recruitment of TRAF2 and RIPK1 and promotes apoptosis. The skin cancer-associated EVER2 I306 allele results in an impaired TRADD–EVER2 interaction, with lower levels of cell death following treatment with TNF-α. These data highlight a new, critical function of EVER2 in controlling cell survival in response to death stimuli.

Highlights

Homozygous mutations in EVER1 (TMC6) or EVER2 (TMC8) gene are associated with EV.[3]
We found that EVER2 triggered tumor necrosis factor alpha (TNF-a)- and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, but had no effect on Fas ligand (FasL) stimulation
We first quantified the effect of EVER2 expression in HEK-293T cells grown in complete medium supplemented with 10% fetal calf serum (FCS), and confirmed that this protein had a dose-dependent effect on cell death rates (Figure 1a)

Summary

Introduction

Homozygous mutations in EVER1 (TMC6) or EVER2 (TMC8) gene are associated with EV.[3]. We found that EVER2 triggered TNF-a- and TRAIL-induced apoptosis, but had no effect on FasL stimulation. We stimulated EVER2-expressing HEK-293T cells with TNF-a, TRAIL and Fas ligand (FasL) in the absence of ‘sensitizer’ adjuvants (e.g. cycloheximide, CHX), to determine which stimuli induced cell death in our model.

Results

Conclusion