title: Brn3a regulation of TrkA/NGF receptor expression in developing sensory neurons.
abstract: The TrkA/NGF receptor is essential for the survival and differentiation of sensory neurons. The molecular mechanisms regulating tissue and stage-specific expression of TrkA are largely unknown. The Brn3a POU-domain transcription factor has been implicated in the development of the PNS and proposed as a transcription regulator for TrkA. The molecular mechanisms underlying the regulation of TrkA by Brn3a is unclear. In this study, we provide genetic, transgenic and biochemical evidence that Brn3a binds to novel, specific sites in the 457 bp enhancer that regulates TrkA expression in embryonic sensory neurons. We employ Bax-knockout mice, in which sensory neurons no longer require neurotrophins for survival, to uncouple TrkA-dependent cell death from downregulation of TrkA expression. In addition, when mutagenized, the novel Brn3a-binding sites identified fail to drive appropriate reporter transgene expression in sensory neurons. Thus, TrkA, a gene that is crucial for the differentiation and survival of sensory nociceptive neurons, requires Brn3a to maintain normal transcriptional activity.
authors.affiliation: Center for Developmental Biology and Kent Waldrep Foundation Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, TX 75390-9133, USA.
authors.forename: Long
authors.initials: L
authors.lastname: Ma
authors.forename: Lei
authors.initials: L
authors.lastname: Lei
authors.forename: S Raisa
authors.initials: SR
authors.lastname: Eng
authors.forename: Eric
authors.initials: E
authors.lastname: Turner
authors.forename: Luis F
authors.initials: LF
authors.lastname: Parada
mesh_terms: D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D009420:Nervous System / Q000196:embryology*; D009475:Neurons, Afferent / Q000378:metabolism*; D020800:Receptor, Nerve Growth Factor / Q000096:biosynthesis / Q000235:genetics*; D020917:Receptor, trkA / Q000096:biosynthesis / Q000235:genetics*; D050818:Transcription Factor Brn-3; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C494188:POU4F1 protein, human; D020800:Receptor, Nerve Growth Factor; D050818:Transcription Factor Brn-3; D050819:Transcription Factor Brn-3A; D014157:Transcription Factors; D020917:Receptor, trkA