Annotation of sheep keratin intermediate filament genes and their patterns of expression

Abstract

Keratin IF (KRT) and keratin-associated protein genes encode the majority of wool and hair proteins. We have identified cDNA sequences representing nine novel sheep KRT genes, increasing the known active genes from eight to 17, a number comparable to that in the human. However, the absence of KRT37 in the type I family and the discovery of type II KRT87 in sheep exemplify species-specific compositional differences in hair KRT genes. Phylogenetic analysis of hair KRT genes within type I and type II families in the sheep, cattle and human genomes revealed a high degree of consistency in their sequence conservation and grouping. However, there were differences in the fibre compartmentalisation and keratinisation zones for the expression of six ovine KRT genes compared with their human orthologs. Transcripts of three genes (KRT40, KRT82 and KRT84) were only present in the fibre cuticle. KRT32, KRT35 and KRT85 were expressed in both the cuticle and the fibre cortex. The remaining 11 genes (KRT31, KRT33A, KRT33B, KRT34, KRT36, KRT38-39, KRT81, KRT83 and KRT86-87) were expressed only in the cortex. Species-specific differences in the expressed keratin gene sets, their relative expression levels and compartmentalisation are discussed in the context of their underlying roles in wool and hair developmental programmes and the distinctive characteristics of the fibres produced.

The proteomics of wool fibre morphogenesis

“…Our results validate earlier findings which relied on indirect labelling methods, in particular those of Yu and colleagues' mRNA labelling work on follicles of Wiltshire sheep 11 . Also, in the general sense that wool and human scalp and beard follicles share a good deal of common biology, we find that our results follow a similar pattern to the immunocytochemistry and mRNA results of Langbein and colleagues 7 .…”

“…Also, in the general sense that wool and human scalp and beard follicles share a good deal of common biology, we find that our results follow a similar pattern to the immunocytochemistry and mRNA results of Langbein and colleagues 7 . As with those earlier studies, we conclude from our results that keratins first appear in the cortex at the beginning of Zone B, with K35 and K85 being the first to appear followed shortly after by K31 [8][9][10][11] . The proteomic methods will continue to detect proteins after expression has stopped, provided the proteins are not destroyed.…”

“…Some keratins, such as K32, K40 and K82 are found exclusively in the cuticle. Others, including K31, K33a, K34, K36, K37, K38, K81, K83 and K86, are restricted to the cortex, and K35, K39 and K85 are expressed in both fibre cell lines [8][9][10][11] . Like keratins, a large number of fibre-specific KAPs (79 of them in sheep; Z.…”

Wool‐derived keratin stimulates human keratinocyte migration and types IV and VII collagen expression

“…Keratin-based wound care devices have been approved for use in several regions of the world including use as a topical agent for wound care (9). With keratin intermediate filaments as major components, ovine wool shares high similarity with human hair (12). Clinicians using wool-derived oxidized keratin have found improved healing for hard to heal chronic wounds (13).…”

Unravelling the proteome of wool: Towards markers of wool quality traits

“…Two major types are present, the intermediate filamentforming keratin proteins and the keratin associated proteins (KAPs) [2]. The keratins are further divided into two types, the acidic Type Is and the neutral-basic Type IIs [3][4][5][6]. The KAPs have been divided into three classes: high sulphur proteins (HSPs), ultra-high sulphur proteins (UHSPs) and high glycinetyrosine proteins (HGTPs) [2], though from studies of human hair some new KAPs have been identified that do not fit into any of these categories [7].…”