Omi/HtrA2 promotes cell death by binding and degrading the anti-apoptotic protein ped/pea-15.
ped/pea-15 is a ubiquitously expressed 15-kDa protein featuring a broad anti-apoptotic function. In a yeast two-hybrid screen, the pro-apoptotic Omi/HtrA2 mitochondrial serine protease was identified as a specific interactor of the ped/pea-15 death effector domain. Omi/HtrA2 also bound recombinant ped/pea-15 in vitro and co-precipitated with ped/pea-15 in 293 and HeLa cell extracts. In these cells, the binding of Omi/HtrA2 to ped/pea-15 was induced by UVC exposure and followed the mitochondrial release of Omi/HtrA2 into the cytoplasm. Upon UVC exposure, cellular ped/pea-15 protein expression levels decreased. This effect was prevented by the ucf-101 specific inhibitor of the Omi/HtrA2 proteolytic activity, in a dose-dependent fashion. In vitro incubation of ped/pea-15 with Omi/HtrA2 resulted in ped/pea-15 degradation. In intact cells, the inhibitory action of ped/pea-15 on UVC-induced apoptosis progressively declined at increasing Omi/HtrA2 expression. This further effect of Omi/HtrA2 was also inhibited by ucf-101. In addition, ped/pea-15 expression blocked Omi/HtrA2 co-precipitation with the caspase inhibitor protein XIAP and caspase 3 activation. Thus, in part, apoptosis following Omi/HtrA2 mitochondrial release is mediated by reduction in ped/pea-15 cellular levels. The ability of Omi/HtrA2 to relieve XIAP inhibition on caspases is modulated by the relative levels of Omi/HtrA2 and ped/pea-15.
Dipartimento di Biologia e Patologia Cellulare e Molecolare and Istituto di Endocrinologia ed Oncologia Sperimentale del CNR, Università degli Studi di Napoli Federico II, Naples 80131, Italy.
Alessandra
A
Trencia
Francesca
F
Fiory
Maria Alessandra
MA
Maitan
Pasquale
P
Vito
Alessia Paola Maria
AP
Barbagallo
Anna
A
Perfetti
Claudia
C
Miele
Paola
P
Ungaro
Francesco
F
Oriente
Lucia
L
Cilenti
Antonis S
AS
Zervos
Pietro
P
Formisano
Francesco
F
Beguinot
D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D000074923:High-Temperature Requirement A Serine Peptidase 2; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D010750:Phosphoproteins / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000502:physiology*; D013347:Subcellular Fractions; D014162:Transfection; D020798:Two-Hybrid System Techniques; D014466:Ultraviolet Rays; D051636:X-Linked Inhibitor of Apoptosis Protein; D001616:beta-Galactosidase / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; C092039:PEA15 protein, human; D010750:Phosphoproteins; D011506:Proteins; D011994:Recombinant Proteins; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D005982:Glutathione Transferase; D001616:beta-Galactosidase; D012697:Serine Endopeptidases; C000615914:HTRA2 protein, human; D000074923:High-Temperature Requirement A Serine Peptidase 2; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases