title: Regulation of Brn-3a N-terminal transcriptional activity by MEK1/2-ERK1/2 signalling in neural differentiation.
abstract: The POU family transcription factor Brn-3a is required for the differentiation and survival of sensory neurones, and is phosphorylated in neuroblastoma cells following treatment with all-trans retinoic acid (RA). Mutation of serines-121 and -122 of Brn-3a to alanine blocks its phosphorylation and impairs RA-mediated neurite outgrowth. Here we show that this deficit in differentiation is mimicked by a single mutation at serine-122, and demonstrate a similar requirement for a second residue, threonine-39. Like Brn-3a, the neuropeptide Galanin has been implicated in the development of sensory neurones. We show that Brn-3a over-expression acts synergistically with RA treatment to up-regulate Galanin promoter activity; that the activity of the N-terminal transcriptional activation domain of Brn-3a is increased following RA treatment; and that both these effects require threonine-39 and serine-122. In addition, we demonstrate that the RA-mediated activation of Galanin promoter activity and Brn-3a N-terminal transcriptional activity are both blocked by pan-MEK inhibitors, and show that the expression of a constitutively-active mutant of MEK1, but not MEK5, is sufficient to increase Brn-3a activity. These results reveal an important role for the ERK1/2 pathway in Brn-3a regulation during RA-mediated neuronal differentiation and define the neuropeptide Galanin as a novel target of this transcription factor.
authors.affiliation: Medical Molecular Biology Unit, UCL Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK. d.berwick@ich.ucl.ac.uk
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Berwick
authors.forename: Mattia
authors.initials: M
authors.lastname: Calissano
authors.forename: Jacqueline D
authors.initials: JD
authors.lastname: Corness
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Cook
authors.forename: David S
authors.initials: DS
authors.lastname: Latchman
mesh_terms: D000818:Animals; D002460:Cell Line; D019004:Galanin / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048671:MAP Kinase Kinase 5 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020125:Mutation, Missense; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects; D051381:Rats; D050819:Transcription Factor Brn-3A / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology*; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D050819:Transcription Factor Brn-3A; D014212:Tretinoin; D019004:Galanin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D048671:MAP Kinase Kinase 5