Requirement for frzb and fzd7a in cranial neural crest convergence and extension mechanisms during zebrafish palate and jaw morphogenesis.
Regulation of convergence and extension by wnt-frizzled signaling is a common theme in embryogenesis. This study examines the functional requirements of frzb and fzd7a in convergence and extension mechanisms during craniofacial development. Using a morpholino knockdown approach, we found that frzb and fzd7a are dispensable for directed migration of the bilateral trabeculae, but necessary for the convergence and extension of the palatal elements, where the extension process is mediated by chondrocyte proliferation, morphologic change and intercalation. In contrast, frzb and fzd7a are required for convergence of the mandibular prominences, where knockdown of either frzb or fzd7a resulted in complete loss of lower jaw structures. Further, we found that bapx1 was specifically downregulated in the wnt9a/frzb/fzd7a morphants, while general neural crest markers were unaffected. In addition, expression of wnt9a and frzb was also absent in the edn-/- mutant. Notably, over-expression of bapx1 was sufficient to partially rescue mandibular elements in the wnt9a/frzb/fzd7a morphants, demonstrating genetic epistasis of bapx1 acting downstream of edn1 and wnt9a/frzb/fzd7a in lower jaw development. This study underscores the important role of wnt-frizzled signaling in convergence and extension in palate and craniofacial morphogenesis, distinct regulation of upper vs. lower jaw structures, and integration of wnt-frizzled with endothelin signaling to coordinate shaping of the facial form.
['Kamel|George|G|', 'Hoyos|Tatiana|T|', 'Rochard|Lucie|L|', 'Dougherty|Max|M|', 'Kong|Yawei|Y|', 'Tse|William|W|', 'Shubinets|Valeriy|V|', 'Grimaldi|Michael|M|', 'Liao|Eric C|EC|']
D000818:Animals D017209:Apoptosis D019521:Body Patterning D049109:Cell Proliferation D019902:Chondrocytes D004625:Embryo, Nonmammalian D004843:Epistasis, Genetic D018507:Gene Expression Regulation, Developmental D006023:Glycoproteins D057809:HEK293 Cells D018398:Homeodomain Proteins D006801:Humans D047908:Intracellular Signaling Peptides and Proteins D007568:Jaw D009024:Morphogenesis D009432:Neural Crest D010159:Palate D011956:Receptors, Cell Surface D014157:Transcription Factors D051153:Wnt Proteins D015027:Zebrafish D029961:Zebrafish Proteins
frzb fzd7a Cranial neural crest Zebrafish Craniofacial Wnt9a Convergence extension frizzled wnt