title: Multiple signaling conduits regulate global differentiation-specific gene expression in PC12 cells.
abstract: PC12 cells serve as a model for exploring nerve growth factor (NGF)-stimulated signal pathways that mediate neural differentiation. We previously demonstrated that neurofilament light chain (NFLC) gene induction by NGF requires collaborative extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling. Herein, we investigate the broader requirement for integrated ERK and JNK signaling in NGF-stimulated gene expression. NGF stimulates differentiation as well as maintenance of cell viability while insulin-like growth factor-1 (IGF-1) stimulates only trophic actions in PC12 cells. Affymetrix Genechips were used to identify genes whose expression specifically increased in response to NGF, but not IGF-1. From the set of NGF-specific genes, the induction by NGF of ten genes with diverse predicted cellular functions was tested for ERK and JNK pathway requirements using the protein kinase inhibitors, PD98059 and SP600125, respectively. Like NFLC, induction of urokinase plasminogen activator (uPAR), transin/matrix metalloproteinase 3 (MMP3), Fra-1 and transforming growth factor beta 1 (TGF beta 1) required collaborative ERK and JNK signaling while the increased expression of cortexin, rat collapsin response mediator protein 4 (rCRMP4), rat growth and transformation-dependent protein (RGT), and synapsin II required neither mitogen-activated protein kinase (MAPK) pathway. NGF-induction of the bradykinin B2 receptor and c-Ret mRNAs was partially inhibited by SP600125, but not PD98059. Reporter constructs containing the promoters for ERK/JNK-dependent genes (NFLC, transin, uPAR) as well as an ERK/JNK-independent gene (synapsin II) revealed that both sets of genes required functional Ras signaling for activation by NGF. Integrated signaling through the ERK and JNK MAPKs, therefore, represents a general conduit for NGF-dependent gene expression, but additional Ras-dependent signaling pathways distinct from the ERKs and JNKs must contribute as well. Thus, multiple signaling conduits control global differentiation-specific gene expression in PC12 cells.
authors.affiliation: Department of Medicine, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Marek
authors.forename: Valerie
authors.initials: V
authors.lastname: Levresse
authors.forename: Claudia
authors.initials: C
authors.lastname: Amura
authors.forename: Eve
authors.initials: E
authors.lastname: Zentrich
authors.forename: Vicki
authors.initials: V
authors.lastname: Van Putten
authors.forename: Raphael A
authors.initials: RA
authors.lastname: Nemenoff
authors.forename: Lynn E
authors.initials: LE
authors.lastname: Heasley
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020932:Nerve Growth Factor / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D016716:PC12 Cells; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D016704:Synapsins / Q000378:metabolism; D015533:Transcriptional Activation; D000099169:Fos-Related Antigen 1
chemical_list: D048049:Extracellular Signal-Regulated MAP Kinases; D007334:Insulin-Like Growth Factor I; D048031:JNK Mitogen-Activated Protein Kinases; D020932:Nerve Growth Factor; D016760:Proto-Oncogene Proteins c-fos; D016283:Proto-Oncogene Proteins p21(ras); D016704:Synapsins; D000099169:Fos-Related Antigen 1; C501009:HRAS protein, human