Cell-Autonomous and Non-Cell-Autonomous Roles for Irf6 during Development of the Tongue

Steven Goudy,Scott Baldwin,Brian C Schutte,Veronica Mainini,Britni Jacobs,Lawrence S Prince,Cynthia Hill,Peggi Angel,Richard Caprioli,Arianna L Smith,Youssef A Kousa,Andreas Bergmann

doi:10.1371/journal.pone.0056270

Abstract

Interferon regulatory factor 6 (IRF6) encodes a highly conserved helix-turn-helix DNA binding protein and is a member of the interferon regulatory family of DNA transcription factors. Mutations in IRF6 lead to isolated and syndromic forms of cleft lip and palate, most notably Van der Woude syndrome (VWS) and Popliteal Ptyerigium Syndrome (PPS). Mice lacking both copies of Irf6 have severe limb, skin, palatal and esophageal abnormalities, due to significantly altered and delayed epithelial development. However, a recent report showed that MCS9.7, an enhancer near Irf6, is active in the tongue, suggesting that Irf6 may also be expressed in the tongue. Indeed, we detected Irf6 staining in the mesoderm-derived muscle during development of the tongue. Dual labeling experiments demonstrated that Irf6 was expressed only in the Myf5+ cell lineage, which originates from the segmental paraxial mesoderm and gives rise to the muscles of the tongue. Fate mapping of the segmental paraxial mesoderm cells revealed a cell-autonomous Irf6 function with reduced and poorly organized Myf5+ cell lineage in the tongue. Molecular analyses showed that the Irf6−/− embryos had aberrant cytoskeletal formation of the segmental paraxial mesoderm in the tongue. Fate mapping of the cranial neural crest cells revealed non-cell-autonomous Irf6 function with the loss of the inter-molar eminence. Loss of Irf6 function altered Bmp2, Bmp4, Shh, and Fgf10 signaling suggesting that these genes are involved in Irf6 signaling. Based on these data, Irf6 plays important cell-autonomous and non-cell-autonomous roles in muscular differentiation and cytoskeletal formation in the tongue.

Highlights

Interferon regulatory factor 6 (IRF6) encodes a highly conserved winged-helix DNA binding protein and is a member of the interferon regulatory family of DNA transcription factors
Cell lineage tracing of MCS9.7, an enhancer element whose activity replicates most of the endogenous Irf6 pattern of expression, suggested that Irf6 may be expressed in mesodermal tissues in the developing tongue [6]
In the Tongue A great degree of interest has been focused on the role of Irf6 during epithelial development

Summary

Introduction

Interferon regulatory factor 6 (IRF6) encodes a highly conserved winged-helix DNA binding protein and is a member of the interferon regulatory family of DNA transcription factors. IRF6 is highly expressed in epithelial cells and mutations in IRF6 are responsible for Van der Woude (VWS) and popliteal pterygium syndrome (PPS), two autosomal dominant forms of cleft lip and palate. Mutations in IRF6 lead to multiple associated findings, from lower lip pits in VWS patients to webbing of the limbs, syngnathia, ankyloblepharon, and urogenital abnormalities in PPS patients [1]. In mice with mutations in the Irf gene, a wide array of similar anomalies seen in PPS patients were observed such as webbing of the limbs, syngnathia, and esophageal adhesion [2,3]. In examining the cleft palate phenotype of these mice, there were severe adhesions throughout the oral cavity epithelium, preventing normal palate elevation and apposition. To date all of the investigation on Irf mice has focused on the epithelial phenotype, but the requirement of Irf during mesenchymal development is unknown

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Results

Conclusion