title: Auto and cross regulatory elements control Onecut expression in the ascidian nervous system.
abstract: The expression pattern of Onecut genes in the central and peripheral nervous systems is highly conserved in invertebrates and vertebrates but the regulatory networks in which they are involved are still largely unknown. The presence of three gene copies in vertebrates has revealed the functional roles of the Onecut genes in liver, pancreas and some populations of motor neurons. Urochordates have only one Onecut gene and are the closest living relatives of vertebrates and thus represent a good model system to understand its regulatory network and involvement in nervous system formation. In order to define the Onecut genetic cascade, we extensively characterized the Onecut upstream cis-regulatory DNA in the ascidian Ciona intestinalis. Electroporation experiments using a 2.5kb genomic fragment and of a series of deletion constructs identified a small region of 262bp able to reproduce most of the Onecut expression profile during embryonic development. Further analyses, both bioinformatic and in vivo using transient transgenes, permitted the identification of transcription factors responsible for Onecut endogenous expression. We provide evidence that Neurogenin is a direct activator of Onecut and that an autoregulatory loop is responsible for the maintenance of its expression. Furthermore, for the first time we propose the existence of a direct connection among Neurogenin, Onecut and Rx transcription factors in photoreceptor cell formation.
authors.affiliation: Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy. Electronic address: mariarosa.pezzotti@szn.it.
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Pezzotti
authors.affiliation: Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Locascio
authors.affiliation: Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Racioppi
authors.affiliation: Biology Department, University of Naples Federico II, Via Cinthia, 80126 Napoli, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Fucci
authors.affiliation: Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy. Electronic address: margherita.branno@szn.it.
authors.forename: Margherita
authors.initials: M
authors.lastname: Branno
mesh_terms: D000818:Animals; D018274:Electroporation; D005786:Gene Expression Regulation / Q000235:genetics*; D006651:Histocytochemistry; D017403:In Situ Hybridization; D007558:Italy; D008522:Mediterranean Sea; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009420:Nervous System / Q000196:embryology / Q000378:metabolism*; D051558:Onecut Transcription Factors / Q000235:genetics / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000378:metabolism / Q000502:physiology*; D050436:Regulatory Elements, Transcriptional / Q000235:genetics*; D059467:Transcriptome; D014561:Urochordata / Q000235:genetics*
chemical_list: D009419:Nerve Tissue Proteins; D051558:Onecut Transcription Factors
keywords: Ciona intestinalis; Nervous system; Neurogenin; Onecut enhancer; Photoreceptor cells