c-Jun-dependent CD95-L expression is a rate-limiting step in the induction of apoptosis by alkylating agents.
Mouse 3T3 fibroblasts derived from fetuses lacking c-Jun were used to define an essential role of c-Jun, a main component of the transcription factor AP-1, in the cellular response to the alkylating agent methyl methanesulfonate (MMS). MMS represents the most potent and selective activator of the stress-induced kinases JNK/SAPK and p38, resulting in very efficient induction of c-Jun hyperphosphorylation and c-jun transcription. This agent induced apoptosis with high efficiency in wild-type cells but not in c-jun(-/-) cells. Resistance to apoptosis was accompanied by impaired expression of CD95 ligand (CD95-L), a well-known inducer of apoptosis. The addition of recombinant CD95-L restored apoptosis sensitivity in c-jun(-/-) fibroblasts. MMS-induced apoptosis in wild-type fibroblasts or human lymphocytes was strongly reduced by neutralizing CD95-L antibodies or transdominant negative FADD, confirming the importance of CD95 signalling in MMS-induced apoptosis. The loss-of-function approach in fibroblasts allowed the identification and dissection of c-Jun-dependent and -independent processes upstream or downstream of CD95 activation. We have found that c-Jun can act as a proapoptotic regulator in cells exposed to DNA damage via induction of CD95-L. Once activated, CD95-induced death signalling is not affected by the loss of c-Jun, demonstrating that only the initiation and not the execution of stress-induced apoptosis depends on c-Jun.
Kolbus
A
A
Division of Signal Transduction and Growth Control, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany.
Herr
I
I
Schreiber
M
M
Debatin
K M
KM
Wagner
E F
EF
Angel
P
P
D051698:Activating Transcription Factor 2; D048868:Adaptor Proteins, Signal Transducing; D000477:Alkylating Agents / Q000494:pharmacology*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D051379:Mice; D016755:Proto-Oncogene Proteins c-jun / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects*
D051698:Activating Transcription Factor 2; D048868:Adaptor Proteins, Signal Transducing; D000477:Alkylating Agents; D000906:Antibodies; D002352:Carrier Proteins; D017362:Cyclic AMP Response Element-Binding Protein; C505533:FADD protein, human; C505661:FASLG protein, human; C505534:Fadd protein, mouse; D053222:Fas Ligand Protein; D053200:Fas-Associated Death Domain Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D011994:Recombinant Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D008741:Methyl Methanesulfonate