We studied the roles of Notch, Delta, and Serrate in vertebrate epithelial appendage morphogenesis using feather as a model and found the following. (1) C-Notch-1, C-Delta-1, and C-Serrate-1 are not expressed at the early placode stage and are therefore not involved in the determination of bad versus interbud compartments. (2) From symmetric short buds to asymmetric long buds, C-Delta-1 and C-Serrate-1 are expressed in the posterior bud mesenchyme in a nested fashion, while C-Notch-1 is expressed as a stripe perpendicular to the anterior-posterior (A-P) axis and positioned posterior to the midpoint. (3) Epithelial-mesenchymal recombination with rotation led to the disappearance of these genes followed by their reappearance with new positions appearing to predict their new morphological orientation. (4) Conditions leading to branched buds (e.g., recombination of later buds) show polarized staining patterns before branching occurs. (5) Conditions leading to symmetrical round buds (e.g., treated with the protein kinase A agonist forskolin) suppress expression of all three genes. These results lead us to hypothesize that Notch, Delta, and Serrate are involved in establishing the A-P asymmetry of feather buds.
Bibliographical noteFunding Information:
We thank Drs. Julian Lewis, Domingos Henrique, and Anna Myat for providing in situ probes to C-Notch-1, C-Delta-1, and C-Serrate-1. We thank Dr. Randall B. Widelitz for help in discussion and computer graphics. We thank Mr. Ying-Hsien Kao for excellent technical assistance. This work is supported by grants from NSF, NIH, and CTR (C.M.C.).
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Developmental Biology
- Cell Biology