Region‐specific patterns of beta keratin expression during avian skin development

Abstract

The transient embryonic layers primarily composed of a periderm and subperiderm cover most regions of the chick embryo and are the first suprabasal cell layers covering the body ectoderm. This study presents evidence for regional vriation in the expression of beta keratin in the embryonic layers. Here we show that the embryonic layers covering the anterior metatarsal region of the chicken hindlimb (scutate scale forming region) produce several members of the beta keratin family of polypeptides, designated beta (β) 1–7. These specific polypeptides are later expressed in this region exclusively in the thick, cornified beta strata of mature scutate scales. In contrast to this sequence of events, the embryonic layers overlying the epidermis of the ventral foot pad (reticulate scale‐forming region) and those covering the epidermis in apteric regions of the body produce beta keratin polypeptides β1–3 and β2,3, respectively, but no subsequent expression of these proteins occurs in the mature epidermises of these regions. Furthermore, we find that the embryonic layers of the skin overlying the anterior metatasal region of birds homozygous for the mutation “scaleless” (sc/sc), which completely lack scutate scales, produce the same members of the beta keratin family, β1–7, as the embryonic layers and beta strata of normal scutate scales. Thus, the accumulation of specific beta keratin polypeptides in the developing anterior metatarsal region appears to occur in two distinct phases; first, an early region‐specific expression in cells of the embryonic layers followed by a second phase of expression which occurs in conjunction with appendage morphogenesis. The relationship between differentiation of embryonic skin and the expression of beta keratins is discussed. © 1993 wiley‐Liss, Inc.

Topographical mapping of α- and β-keratins on developing chicken skin integuments: Functional interaction and evolutionary perspectives

“…α-and β-keratins have been characterized by biochemical and immunocytochemical analyses (1,44). In birds, α-keratins (intermediate filament proteins) produce α-X-ray patterns that are present in various skin appendages (1).…”

Specific activation in jun-transformed avian fibroblasts of a gene (bkj) related to the avian beta-keratin gene family.

“…The predicted protein product of the bkj gene is structurally related to the large family of avian ,B-keratins found in epidermal cells and their appendages. Their expression is tightly regulated at the transcriptional level during embryonic development and cellular differentiation (26,32,33). Another family of keratins, structurally unrelated to the ,B-keratins, are the a-helical cytokeratins that form the intermediate filaments of epithelial cells and their appendages (34).…”

Expressed miRNAs target feather related mRNAs involved in cell signaling, cell adhesion and structure during chicken epidermal development

“…However, at the protein level, only a few β-keratin species can be detected from scale and feather tissues on 2-dimensional gels at the same developmental stages (Knapp et al, 1991; Knapp et al, 1993; Rice et al, 2013; Shames and Sawyer, 1986; Shames et al, 1988), suggesting that β-keratin mRNAs are being regulated possibly by miRNAs.…”