The proapoptotic dp5 gene is a direct target of the MLK-JNK-c-Jun pathway in sympathetic neurons.
The death of sympathetic neurons after nerve growth factor (NGF) withdrawal requires de novo gene expression. Dp5 was one of the first NGF withdrawal-induced genes to be identified and it encodes a proapoptotic BH3-only member of the Bcl-2 family. To study how dp5 transcription is regulated by NGF withdrawal we cloned the regulatory regions of the rat dp5 gene and constructed a series of dp5-luciferase reporter plasmids. In microinjection experiments with sympathetic neurons we found that three regions of dp5 contribute to its induction after NGF withdrawal: the promoter, a conserved region in the single intron, and sequences in the 3' untranslated region of the dp5 mRNA. A construct containing all three regions is efficiently activated by NGF withdrawal and, like the endogenous dp5, its induction requires mixed-lineage kinase (MLK) and c-Jun N-terminal kinase (JNK) activity. JNKs phosphorylate the AP-1 transcription factor c-Jun, and thereby increase its activity. We identified a conserved ATF site in the dp5 promoter that binds c-Jun and ATF2, which is critical for dp5 promoter induction after NGF withdrawal. These results suggest that part of the mechanism by which the MLK-JNK-c-Jun pathway promotes neuronal apoptosis is by activating the transcription of the dp5 gene.
Towers
Emily
E
Molecular Haematology and Cancer Biology Unit, Camelia Botnar Laboratories, UCL Institute of Child Health, London, UK.
Gilley
Jonathan
J
Randall
Rebecca
R
Hughes
Rosie
R
Kristiansen
Mark
M
Ham
Jonathan
J
D020413:3' Untranslated Regions / Q000737:chemistry; D051698:Activating Transcription Factor 2 / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D007438:Introns; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D020932:Nerve Growth Factor / Q000502:physiology; D009474:Neurons / Q000201:enzymology / Q000378:metabolism*; D009479:Neuropeptides / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017783:Superior Cervical Ganglion / Q000166:cytology
D020413:3' Untranslated Regions; D051698:Activating Transcription Factor 2; D051017:Apoptosis Regulatory Proteins; C484585:Hrk protein, rat; D009479:Neuropeptides; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D020932:Nerve Growth Factor; D020930:MAP Kinase Kinase Kinases; D048670:MAP Kinase Kinase 4