title: Identification and functional analysis of novel facial patterning genes in the duplicated beak chicken embryo.
abstract: Cranial neural crest cells form the majority of the facial skeleton. However exactly when the pattering information and hence jaw identity is established is not clear. We know that premigratory neural crest cells contain a limited amount of information about the lower jaw but the upper jaw and facial midline are specified later by local tissue interactions. The environmental signals leading to frontonasal identity have been explored by our group in the past. Altering the levels of two signaling pathways (Bone Morphogenetic Protein) and retinoic acid (RA) in the chicken embryo creates a duplicated midline on the side of the upper beak complete with egg tooth in place of maxillary derivatives (Lee et al., 2001). Here we analyze the transcriptome 16 h after bead placement in order to identify potential mediators of the identity change in the maxillary prominence. The gene list included RA, BMP and WNT signaling pathway genes as well as transcription factors expressed in craniofacial development. There was also cross talk between Noggin and RA such that Noggin activated the RA pathway. We also observed expression changes in several poorly characterized genes including the upregulation of Peptidase Inhibitor-15 (PI15). We tested the functional effects of PI15 overexpression with a retroviral misexpression strategy. PI15 virus induced a cleft beak analogous to human cleft lip. We next asked whether PI15 effects were mediated by changes in expression of major clefting genes and genes in the retinoid signaling pathway. Expression of TP63, TBX22, BMP4 and FOXE1, all human clefting genes, were upregulated. In addition, ALDH1A2, ALDH1A3 and RA target, RARβ were increased while the degradation enzyme CYP26A1 was decreased. Together these changes were consistent with activation of the RA pathway. Furthermore, PI15 retrovirus injected into the face was able to replace RA and synergize with Noggin to induce beak transformations. We conclude that the microarrays have generated a rich dataset containing genes with important roles in facial morphogenesis. Moreover, one of these facial genes, PI15 is a putative clefting gene and is in a positive feedback loop with RA.
authors.affiliation: Life Sciences Institute, Department of Oral Health Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Suresh
authors.initials: S
authors.lastname: Nimmagadda
authors.affiliation: Life Sciences Institute, Department of Oral Health Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Marcela
authors.initials: M
authors.lastname: Buchtová
authors.affiliation: Life Sciences Institute, Department of Oral Health Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Fu
authors.affiliation: Life Sciences Institute, Department of Oral Health Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Poongodi
authors.initials: P
authors.lastname: Geetha-Loganathan
authors.affiliation: Life Sciences Institute, Department of Oral Health Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Hosseini-Farahabadi
authors.affiliation: Harvard Catalyst, Laboratory for Innovative Translational Technologies, Harvard Medical School and the Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Trachtenberg
authors.affiliation: Harvard Catalyst, Laboratory for Innovative Translational Technologies, Harvard Medical School and the Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA, United States.
authors.forename: Winston Patrick
authors.initials: WP
authors.lastname: Kuo
authors.affiliation: Life Sciences Institute, Department of Oral Health Sciences, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Iva
authors.initials: I
authors.lastname: Vesela
authors.affiliation: Life Sciences Institute, Department of Oral Health Sciences, University of British Columbia, Vancouver, BC, Canada. Electronic address: richman@dentistry.ubc.ca.
authors.forename: Joy M
authors.initials: JM
authors.lastname: Richman
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001502:Beak / Q000002:abnormalities* / Q000378:metabolism*; D019521:Body Patterning / Q000187:drug effects / Q000235:genetics*; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002642:Chick Embryo; D030541:Databases, Genetic; D005145:Face; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D017403:In Situ Hybridization; D008437:Maxilla / Q000187:drug effects / Q000196:embryology; D020411:Oligonucleotide Array Sequence Analysis; D053491:Proteinase Inhibitory Proteins, Secretory / Q000235:genetics / Q000378:metabolism; D011786:Quality Control; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014212:Tretinoin / Q000378:metabolism / Q000494:pharmacology; D000099176:Noggin Protein
chemical_list: D019485:Bone Morphogenetic Proteins; D002352:Carrier Proteins; D053491:Proteinase Inhibitory Proteins, Secretory; D014212:Tretinoin; D000099176:Noggin Protein
keywords: Bone morphogenetic protein; Chicken embryo; Cleft lip; Craniofacial; Microarray; Noggin; Peptidase Inhibitor 15; Retinoic acid; Rspondin