title: The Xenopus MEF2 gene family: evidence of a role for XMEF2C in larval tendon development.
abstract: MEF2 transcription factors are well-established regulators of muscle development. In this report, we describe the cloning of multiple splicing isoforms of the XMEF2A and XMEF2C encoding genes, differentially expressed during Xenopus development. Using whole-mount in situ hybridization, we found that the accumulation of XMEF2C mRNA in the tadpole stages was restricted to intersomitic regions and to the peripheral edges of hypaxial and cranial muscle masses in contrast to XMEF2A and XMEF2D, characterized by a continuous muscle cell expression. The XMEF2C positive cells express the bHLH transcription factor, Xscleraxis, known as a specific marker for tendons. Gain of function experiments revealed that the use of a hormone-inducible XMEF2C construct is able to induce Xscleraxis expression. Furthermore, XMEF2C specifically cooperates with Xscleraxis to induce tenascin C and betaig-h3, two genes preferentially expressed in Xenopus larval tendons. These findings 1) highlight a previously unappreciated and specific role for XMEF2C in tendon development and 2) identify a novel gene transactivation pathway where MEF2C cooperates with the bHLH protein, Xscleraxis, to activate specific gene expression.
authors.affiliation: UMR 7060 CNRS, Equipe Biologie du Développement et de la Différenciation Neuromusculaire, Centre Universitaire des Saints-Pères, 45, rue des Saints-Pères, Université Paris Descartes, F-75270 Paris Cedex 06, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: della Gaspera
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Armand
authors.forename: Ines
authors.initials: I
authors.lastname: Sequeira
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lecolle
authors.forename: Claude Louis
authors.initials: CL
authors.lastname: Gallien
authors.forename: Frédéric
authors.initials: F
authors.lastname: Charbonnier
authors.forename: Christophe
authors.initials: C
authors.lastname: Chanoine
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007814:Larva / Q000254:growth & development / Q000502:physiology; D026161:MADS Domain Proteins / Q000235:genetics / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D019063:Tenascin / Q000378:metabolism; D013710:Tendons / Q000254:growth & development / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis / Q000254:growth & development* / Q000502:physiology; D000099222:betaIG-H3 Protein
chemical_list: D016326:Extracellular Matrix Proteins; D026161:MADS Domain Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D019063:Tenascin; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; D000099222:betaIG-H3 Protein