title: Asymmetric expression of Gli transcription factors in Hensen's node.
abstract: Avian left-right (L/R) axis determination involves the establishment of asymmetric gene expression in Hensen's node, resulting in two discrete signalling pathways on the left and right sides of the embryo. The extracellular signalling molecule Sonic Hedgehog (SHH) is known to be an important left-side determinant. Transcription of Shh is initially bilateral in Hensen's node (stage 4), but is restricted to the left side by stage 5. The Gli genes (Gli1, Gli2 and Gli3) are the main transcriptional mediators of the Hedgehog pathway in vertebrates. GLI1 and GLI2 are primarily transcriptional activators of Hedgehog target genes, while GLI3 is primarily a transcriptional repressor of Hedgehog targets. In order to gain insight into the mechanisms of asymmetrical Hedgehog signal transduction in the node, we have analysed the expression patterns of the Gli genes in Hensen's node from stage 4 to stage 8. Here, we reveal that the Gli genes are asymmetrically expressed in Hensen's node: Gli1 and Gli2, are expressed on the left side, while Gli3 is expressed on the right side.
authors.affiliation: MRC Centre for Developmental Neurobiology, King's College London, 4th Floor New Hunt's House, Guy's Hospital Campus, London SE1 1UL, UK.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Granata
authors.forename: Nandita A
authors.initials: NA
authors.lastname: Quaderi
mesh_terms: D000818:Animals; D019521:Body Patterning; D002642:Chick Embryo; D007839:Functional Laterality; D005775:Gastrula / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D009024:Morphogenesis; D015513:Oncogene Proteins / Q000235:genetics*; D020897:Organizers, Embryonic / Q000502:physiology*; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics*; D000071676:Zinc Finger Protein GLI1
chemical_list: D015513:Oncogene Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1