Stoichiometry of the CD95 death-inducing signaling complex: experimental and modeling evidence for a death effector domain chain model.
The CD95 (Fas/APO-1) death-inducing signaling complex (DISC) is essential for the initiation of CD95-mediated apoptotic and nonapoptotic responses. The CD95 DISC comprises CD95, FADD, procaspase-8, procaspase-10, and c-FLIP proteins. Procaspase-8 and procaspase-10 are activated at the DISC, leading to the formation of active caspases and apoptosis initiation. In this study we analyzed the stoichiometry of the CD95 DISC. Using quantitative western blots, mass spectrometry, and mathematical modeling, we reveal that the amount of DED proteins procaspase-8/procaspase-10 and c-FLIP at the DISC exceeds that of FADD by several-fold. Furthermore, our findings imply that procaspase-8, procaspase-10, and c-FLIP could form DED chains at the DISC, enabling the formation of dimers and efficient activation of caspase-8. Taken together, our findings provide an enhanced understanding of caspase-8 activation and initiation of apoptosis at the DISC.
Division of Immunogenetics, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
Kolja
K
Schleich
Uwe
U
Warnken
Nicolai
N
Fricker
Selcen
S
Oztürk
Petra
P
Richter
Kerstin
K
Kammerer
Martina
M
Schnölzer
Peter H
PH
Krammer
Inna N
IN
Lavrik
D017209:Apoptosis; D053455:Caspase 10 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000378:metabolism*; D019281:Dimerization; D053200:Fas-Associated Death Domain Protein / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D008962:Models, Theoretical; D015398:Signal Transduction; D019014:fas Receptor / Q000737:chemistry* / Q000378:metabolism
D053418:Death Domain Receptor Signaling Adaptor Proteins; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D019014:fas Receptor; D053455:Caspase 10; D053181:Caspase 8