A suppressive effect of the adenovirus 5 protein E1B 55K on apoptosis induced by IL-3 deprivation and gamma-irradiation.
The murine IL-3-dependent myeloid cell line 32D undergoes a rapid death when deprived of interleukin-3 (IL-3), a process that is suppressed or delayed by the constitutive expression of Bcl-2 or the Bcl-2-related Bcl-xL survival protein. The adenovirus type 5 E1B region encodes an E1B 55K protein, that has been reported to bind and inactivate the p53 protein that plays an important role in the induction of apoptosis. In order to explore the potential effect of the E1B 55K protein on IL-3 deprival-induced cell death, we have established 32D cell lines overexpressing the adenovirus E1B 55K protein and compared its ability to modulate the cell death with that of the human Bcl-2 protein. We observed that E1B 55K, as Bcl-2, delays the cell death caused by either IL-3-deprivation or DNA damage induced by gamma-irradiation. Cell-cycle analysis after IL-3 deprivation indicated that surviving Bcl-2 transfectants accumulate predominantly in the G0/G1 phase of the cell cycle, while E1B 55K transfectants survive in both G0/G1 and the S and G2/M phases of the cell cycle. zVAD-fmk, a broad caspase inhibitor, prevented chromatin condensation and fragmentation, but not cell death, suggesting that IL-3 deprivation induces a cell death program in which the caspases are dispensable. In contrast, both E1B 55K and Bcl-2 allowed cell survival and prevented the typical features of programmed cell death, such as phosphatidyl-serine exposure, loss of mitochondrial membrane potential, and chromatin condensation and fragmentation. Our findings indicate that the adenovirus 5 E1B 55K protein has the capability to act as a survival factor, and suggest that E1B 55K exerts its effect upstream of the activation of effector caspases, by preventing the loss of mitochondrial membrane potential induced by IL-3 deprivation.
BenJilani
Kamal Eddine
KE
EMI-U 9922 INSERM/Université de PARIS 7 IFR02, AP-HP, Faculté de Médecine Xavier Bichat-Claude Bernard, 16 rue Henri Huchard, 75018 Paris, France. ke_benjilani@parisien.zzn.com
Gaillard
Jean-Philippe
JP
Petit
Frédéric
F
Arnoult
Damien
D
Roumier
Anne-Sophie
AS
Labalette
Myriam
M
Ameisen
Jean-Claude
JC
Estaquier
Jérôme
J
D017501:Adenovirus E1B Proteins / Q000235:genetics / Q000502:physiology*; D000818:Animals; D017209:Apoptosis / Q000502:physiology* / Q000528:radiation effects; D002453:Cell Cycle / Q000502:physiology; D005720:Gamma Rays; D005822:Genetic Vectors; D007377:Interleukin-3 / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D008928:Mitochondria / Q000235:genetics; D022423:Myeloid Cells / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology; D012190:Retroviridae / Q000235:genetics
D017501:Adenovirus E1B Proteins; D007377:Interleukin-3; D019253:Proto-Oncogene Proteins c-bcl-2