Head involution defective (Hid)-triggered apoptosis requires caspase-8 but not FADD (Fas-associated death domain) and is regulated by Erk in mammalian cells.
The molecular machinery of apoptosis is evolutionarily conserved with some exceptions. One such example is the Drosophila proapoptotic gene Head involution defective (Hid), whose mammalian homologue is not known. Hid is apoptotic to mammalian cells, and we have examined the mechanism by which Hid induces death. We demonstrate for the first time a role for the extracellular signal-related kinase-1/2 (Erk-1/2) in the regulation of Hid function in mammalian cells. Bcl-2 and an inhibitor of caspase-9 blocked apoptosis, indicative of a role for the mitochondrion in this pathway, and we provide evidence for a role for caspase-8 in Hid-induced apoptosis. Thus, apoptosis was blocked by an inhibitor of caspase-8, deletion of caspase-8 rendered cells resistant to Hid-induced apoptosis, and Hid associated with caspase-8 in cell lysates. The Fas-associated death domain (FADD) was dispensable for the apoptotic function of Hid, indicating that Hid does not require extracellular death receptor signaling for the activation of caspase-8. In activated T cells, the cytokine interleukin-2 blocked caspase-8 processing and apoptosis, suggesting that survival cues from trophic factors may target a Hid-like intermediate present in mammalian cells. Thus, this study shows that Hid engages with conserved components of cellular death machinery and suggests that apoptotic paradigms characterized by FADD-independent activation of caspase-8 may involve a Hid-like molecule in mammalian cells.
National Centre for Biological Sciences, UAS-GKVK Campus, Bangalore 560065, Karnataka, India.
Jishy
J
Varghese
Hadassah
H
Sade
Peter
P
Vandenabeele
Apurva
A
Sarin
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis / Q000502:physiology* / Q000528:radiation effects; D002352:Carrier Proteins / Q000502:physiology*; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D004330:Drosophila; D029721:Drosophila Proteins; D004789:Enzyme Activation; D053200:Fas-Associated Death Domain Protein; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009479:Neuropeptides / Q000502:physiology*; D014466:Ultraviolet Rays
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D029721:Drosophila Proteins; C505533:FADD protein, human; C505534:Fadd protein, mouse; D053200:Fas-Associated Death Domain Protein; C108880:HID protein, Drosophila; D009479:Neuropeptides; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases