Mutually exclusive subsets of BH3-only proteins are activated by the p53 and c-Jun N-terminal kinase/c-Jun signaling pathways during cortical neuron apoptosis induced by arsenite.
The c-Jun N-terminal protein kinase (JNK)/c-Jun and p53 pathways form distinct death-signaling modules in neurons that culminate in Bax-dependent apoptosis. To investigate whether this signaling autonomy is due to recruitment of particular BH3-only proteins, we searched for a toxic signal that would activate both pathways in the same set of neurons. We show that arsenite activates both the JNK/c-Jun and p53 pathways in cortical neurons, which together account for >95% of apoptosis, as determined by using the mixed-lineage kinase (JNK/c-Jun) pathway inhibitor CEP11004 and p53-null mice. Despite the coexistence of both pathways in at least 30% of the population, Bim mRNA and protein expression was increased only by the JNK/c-Jun signaling pathway, whereas Noxa and Puma mRNA and Puma protein expression was entirely JNK/c-Jun independent. About 50% of Puma/Noxa expression was p53 dependent, with the remaining signal being independent of both pathways and possibly facilitated by arsenite-induced reduction in P-Akt. However, functionally, Puma was predominant in mediating Bax-dependent apoptosis, as evidenced by the fact that more than 90% of apoptosis was prevented in Puma-null neurons, although Bim was still upregulated, while Bim- and Noxa-null neurons died similarly to wild-type neurons. Thus, the p53 and JNK/c-Jun pathways can activate mutually exclusive subclasses of BH3-only proteins in the same set of neurons. However, other factors besides expression may determine which BH3-only proteins mediate apoptosis.
Wong
Hon Kit
HK
Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom.
Fricker
Michael
M
Wyttenbach
Andreas
A
Villunger
Andreas
A
Michalak
Ewa M
EM
Strasser
Andreas
A
Tolkovsky
Aviva M
AM
D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D018053:Arsenites / Q000494:pharmacology*; D000072224:Bcl-2-Like Protein 11; D016923:Cell Death; D017931:DNA Primers / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013347:Subcellular Fractions; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D015854:Up-Regulation
D051017:Apoptosis Regulatory Proteins; D018053:Arsenites; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D017931:DNA Primers; D008565:Membrane Proteins; C488588:PUMA protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D048031:JNK Mitogen-Activated Protein Kinases; C015001:arsenite