Functional Myc-Max heterodimer is required for activation-induced apoptosis in T cell hybridomas.
T cell hybridomas respond to activation signals by undergoing apoptotic cell death, and this is likely to represent comparable events related to tolerance induction in immature and mature T cells in vivo. Previous studies using antisense oligonucleotides implicated the c-Myc protein in the phenomenon of activation-induced apoptosis. This role for c-Myc in apoptosis is now confirmed in studies using a dominant negative form of its heterodimeric binding partner, Max, which we show here inhibits activation-induced apoptosis. Further, coexpression of a reciprocally mutant Myc protein capable of forming functional heterodimers with the mutant Max can compensate for the dominant negative activity and restore activation-induced apoptosis. These results imply that Myc promotes activation-induced apoptosis by obligatory heterodimerization with Max, and therefore, by regulating gene transcription.
La Jolla Institute for Allergy and Immunology, California 92037.
R P
RP
Bissonnette
A
A
McGahon
A
A
Mahboubi
D R
DR
Green
D000818:Animals; D017209:Apoptosis; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D006825:Hybridomas / Q000276:immunology / Q000502:physiology*; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000502:physiology*; D046911:Macromolecular Substances; D016296:Mutagenesis; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology* / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D007376:Interleukin-2; C499330:MAX protein, human; D046911:Macromolecular Substances; C067850:Myc associated factor X; D016271:Proto-Oncogene Proteins c-myc; D014157:Transcription Factors