title: Discrete signal transduction pathway utilization by a neuropeptide (PACAP) and a cytokine (TNF-alpha) first messenger in chromaffin cells, inferred from coupled transcriptome-promoter analysis of regulated gene cohorts.
abstract: Cultured bovine adrenal chromaffin cells (BCCs) are employed to study first messenger-specific signaling by cytokines and neurotransmitters occurring in the adrenal medulla following immune-related stress responses. Here, we show that the cytokine TNF-alpha, and the neuropeptide transmitter PACAP, acting through the TNFR2 and PAC1 receptors, activate distinct signaling pathways, with correspondingly distinct transcriptomic signatures in chromaffin cells. We have carried out a comprehensive integrated transcriptome analysis of TNF-alpha and PACAP gene regulation in BCCs using two microarray platforms to maximize transcript identification. Microarray data were validated using qRT-PCR. More than 90% of the transcripts up-regulated either by TNF-alpha or PACAP were specific to a single first messenger. The final list of transcripts induced by each first messenger was subjected to multiple algorithms to identify promoter/enhancer response elements for trans-acting factors whose activation could account for gene expression by either TNF-alpha or PACAP. Distinct groups of transcription factors potentially controlling the expression of TNF-alpha or PACAP-responsive genes were found: most of the genes up-regulated by TNF-alpha contained transcription factor binding sites for members of the Rel transcription factor family, suggesting TNF-alpha-TNFR2 signaling occurs mainly through the NF-KB signaling pathway. Surprisingly, EGR1 was predicted to be the primary transcription factor controlling PACAP-modulated genes, suggesting PACAP signaling to the nucleus occurs predominantly through ERK, rather than CREB activation. Comparison of TNFR2-dependent versus TNFR1-dependent gene induction, and EGR1-mediated transcriptional activation, may provide a pharmacological avenue to the unique pathways activated by the first messengers TNF-alpha and PACAP in neuronal and endocrine cells.
authors.affiliation: Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, Bethesda, MD 20892, USA.
authors.forename: Babru
authors.initials: B
authors.lastname: Samal
authors.forename: Djida
authors.initials: D
authors.lastname: Ait-Ali
authors.forename: Stephen
authors.initials: S
authors.lastname: Bunn
authors.forename: Tomris
authors.initials: T
authors.lastname: Mustafa
authors.forename: Lee E
authors.initials: LE
authors.lastname: Eiden
mesh_terms: D000311:Adrenal Glands / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D000818:Animals; D002417:Cattle; D019439:Chromaffin Cells / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D004742:Enhancer Elements, Genetic / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000276:immunology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D061251:Primary Cell Culture; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000276:immunology; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I / Q000235:genetics / Q000276:immunology; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction; D013312:Stress, Physiological; D059467:Transcriptome / Q000187:drug effects* / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D016328:NF-kappa B; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D048049:Extracellular Signal-Regulated MAP Kinases