Hox/Pbx and Brn binding sites mediate Pax3 expression in vitro and in vivo

Pax3 is a paired-homeodomain class transcription factor that serves a role in dorsal–ventral and medial–lateral patterning during vertebrate embryogenesis. Its expression is localized to dorsal domains within the developing neural tube and lateral domains within the developing somite. Additionally,...

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Bibliographic Details
Published in:	Gene Expression Patterns Vol. 4; no. 6; pp. 671 - 685
Main Authors:	Pruitt, Steven C., Bussman, Amy, Maslov, Alexander Y., Natoli, Thomas A., Heinaman, Roy
Format:	Journal Article
Language:	English
Published:	Netherlands Elsevier B.V 01-10-2004
Subjects:	Animals Anterior–posterior patterning beta-Galactosidase - metabolism Binding Sites Brn Cell Line Cell Nucleus - metabolism DNA - metabolism DNA-Binding Proteins - biosynthesis Gene Expression Regulation, Developmental Homeodomain Proteins - biosynthesis Homeodomain Proteins - chemistry Homeodomain Proteins - metabolism Hox In Situ Hybridization In Vitro Techniques Meis Mice Mice, Transgenic Mutation Nerve Tissue Proteins Neural Crest - embryology Neural specific Neuropeptides - biosynthesis Neuropeptides - chemistry Paired Box Transcription Factors Pax3 PAX3 Transcription Factor Pbx Plasmids - metabolism POU Domain Factors Pou domain transcription factors promoter elements Promoter Regions, Genetic Protein Binding Protein Structure, Tertiary Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization Time Factors Trans-Activators - biosynthesis Trans-Activators - chemistry Transcription Factors - biosynthesis Transcription Factors - metabolism Transfection Tretinoin - pharmacology Hox promoter elements Anterior–posterior patterning Meis Pbx Pax3 Neural specific Pou domain transcription factors Brn
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Summary:	Pax3 is a paired-homeodomain class transcription factor that serves a role in dorsal–ventral and medial–lateral patterning during vertebrate embryogenesis. Its expression is localized to dorsal domains within the developing neural tube and lateral domains within the developing somite. Additionally, modulation of its expression occurs along the rostral-caudal axis. Previous studies [Development 124 (1997) 617] have localized sequence elements required for expression of Pax3 in the neural tube and neural crest to a 1.6 kbp promoter fragment. In the present study, four discrete DNA elements within the 1.6 kbp promoter fragment are shown by electrophoretic mobility shift assays (EMSA) to exhibit sequence specific interactions with proteins present in nuclear extracts from P19 EC cells induced to express Pax3 by treatment with retinoic acid (RA). Proteins interacting at each of these elements are identified based on biochemical purification using DNA affinity chromatography or a candidate approach. These identifications were confirmed by the ability of specific antibodies to super-shift DNA-protein complexes in EMSA. Two of the four DNA sequence elements are shown to interact with the neural specific Pou-domain class III transcription factors Brn1 and Brn2. The remaining sites contain either consensus binding elements for heterodimers of Pbx and an anterior set of Hox family members, from paralogous groups 1–5, or monomeric Meis and are shown to interact with members of the Pbx and Meis families. Ectopic expression of Brn2 plus HoxA1 but not either factor alone, is sufficient to induce efficient expression from the endogenous Pax3 promoter in P19 EC stem cells under conditions where they would not otherwise express Pax3. Finally, in transgenic mice, mutation of either of the Pou-domain protein binding sites results in reduced expression throughout the neural tube while mutation of the Pbx/Hox binding site results in loss of expression in the anterior domain in which Hox family members from paralogous groups 1–5 are expressed. These observations demonstrate that binding elements for both neural and anterior–posterior position specific transcription factors mediate domains of Pax3 expression.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	1567-133X 1872-7298
DOI:	10.1016/j.modgep.2004.04.006