Interaction of the Adenovirus 14.7-kDa Protein with FLICE Inhibits Fas Ligand-induced Apoptosis

Ping Chen,Jie Tian,Imre Kovesdi,Joseph T Bruder

doi:10.1074/jbc.273.10.5815

Abstract

Adenovirus type 5 encodes a 14.7-kDa protein that protects infected cells from tumor necrosis factor-induced cytolysis by an unknown mechanism. In this report, we demonstrate that infection of cells with an adenovirus vector expressing Fas ligand induced rapid apoptosis that was blocked by coinfection with a virus expressing 14. 7K. Moreover, AdFasL/G infection resulted in the rapid activation of DEVD-specific caspases, and caspase activation was blocked by coinfection with Ad14.7/G. Cell death induced by the overexpression of Fas ligand, Fas-associated death domain-containing protein (FADD)/MORT1, or FADD-like interleukin-1beta-converting enzyme (FLICE)/caspase-8 in a virus-free system was efficiently blocked by 14.7K expression. Moreover, we demonstrate that 14.7K interacts with FLICE. These results support the idea that FLICE is a cellular target for the 14.7-kDa protein.

Highlights

Apoptosis, or programmed cell death, is a physiological process that is required for the normal development and homeostasis of multicellular organisms and involves the destruction of cells that are no longer required or are potentially dangerous [1]
Activation of FADD-like interleukin-1␤converting enzyme (FLICE) occurs at this receptor complex, and it is thought that activated FLICE cleaves and activates downstream DEVD-specific caspases that
14.7K Blocks Apoptosis and DEVD-specific Caspase Activity Induced by FasL—To determine whether 14.7K blocks apoptosis induced by Fas oligomerization, we used an adenovirus vector that expresses FasL to induce apoptosis in 293 cells

Summary

Introduction

Programmed cell death, is a physiological process that is required for the normal development and homeostasis of multicellular organisms and involves the destruction of cells that are no longer required or are potentially dangerous [1]. A, cell lysates harvested at the indicated times post-infection were analyzed by Western blotting with an antibody specific for FasL. At 4 h post-infection, cells were lysed in a buffer containing 1% Triton X-100, 50 mM Tris (pH 8) and 150 mM NaCl. Aliquots (300 ␮g) of cell lysate were incubated with the Ac-DEVD-␣(4-methyl-coumaryl-7-amide) fluorogenic substrate for the indicated time periods (min), and AMC release was measured by spectrofluorometry.

Results

Conclusion