https://doi.org/10.1387/ijdb.130023sy

Vol 58, Issue 1

Developmental expression of chickenFOXN1 and putative target genes during feather development

Developmental Expression Pattern | Published: 17 February 2014

Diana K. Darnell*^,1, Li S. Zhang¹, Sridhar Hannenhalli² and Sergey Y. Yaklichkin*^,3

¹Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ,²Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD and³Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston TX, USA

Abstract

FOXN1 is a member of the forkhead box family of transcription factors. FOXN1 is crucial for hair outgrowth and thymus differentiation in mammals. Unlike the thymus, which is found in all amniotes, hair is an epidermal appendage that arose after the last shared common ancestor between mammals and birds, and hair and feathers differ markedly in their differentiation and gene expression. Here, we show thatFOXN1 is expressed in embryonic chicken feathers, nails and thymus, demonstrating an evolutionary conservation that goes beyond obvious homology. At embryonic day (ED) 12,FOXN1 is expressed in some feather buds and at ED13 expression extends along the length of the feather filament. At ED14FOXN1 mRNA is restricted to the proximal feather filament and is not detectable in distal feather shafts. At the base of the feather,FOXN1 is expressed in the epithelium of the feather sheath and distal barb and marginal plate, whereas in the midsectionFOXN1 transcripts are mainly detected in the barb plates of the feather filament.FOXN1 is also expressed in claws; however, no expression was detected in skin or scales. Despite expression ofFOXN1 in developing feathers, examination of chick homologs of five putative mammalian FOXN1 target genes shows that, while these genes are expressed in feathers, there is little similarity to theFOXN1 expression pattern, suggesting that some gene regulatory networks may have diverged during evolution of epidermal appendages.

Keywords

chick, forkhead, WHN, HFH11, thymus, nudee