Abstract
The transcriptome profile and differential gene expression in telogen and late anagen microdissected hair follicles and the interfollicular epidermis of healthy dogs was investigated by using RNAseq. The genes with the highest expression levels in each group were identified and genes known from studies in other species to be associated with structure and function of hair follicles and epidermis were evaluated. Transcriptome profiling revealed that late anagen follicles expressed mainly keratins and telogen follicles expressed GSN and KRT15. The interfollicular epidermis expressed predominately genes encoding for proteins associated with differentiation. All sample groups express genes encoding for proteins involved in cellular growth and signal transduction. The expression pattern of skin-associated genes in dogs is similar to humans. Differences in expression compared to mice and humans include BMP2 expression mainly in telogen and high KRT17 expression in the interfollicular epidermis of dogs. Our data provide the basis for the investigation of the structure and function of canine skin or skin disease and support the use of dogs as a model for human cutaneous disease by assigning gene expression to specific tissue states.
Highlights
The skin is the largest organ, with various essential functions, including protection/barrier against outside influences and thermoregulation
These results support that the dog is a good model for human skin disease, as we show in this study that the canine gene expression in interfollicular epidermis (IFE) and hair follicles (HF) is much more similar to human follicular and epidermal gene expression, as compared to the mouse
Analyzing genes in our data sets known to be associated with HF and IFE structure and function, stem cell markers and immune function, we found that, in anagen, the hair cycle-associated genes that are most upregulated are MSX2, FOXN1 and HSD17B14, and the most significantly differently expressed genes associated with HF structure is HOXC13
Summary
The skin is the largest organ, with various essential functions, including protection/barrier against outside influences and thermoregulation. To fulfill the protective functions, an intact epidermis and appropriate numbers of hair follicles (HF) are necessary. The interfollicular epidermis (IFE) is composed of a squamous, stratified, multilayered epithelium that frequently self-renews, involving epidermal stem and progenitor cells that reside in the basal layer of the epidermis [2,3]. After the basal epidermal cells detach from the basement membrane, their proliferation ceases and they undergo a terminal cell differentiation program, during which keratinocytes move upwards until they reach the cornified layer as flattened denucleated keratinocytes and are shed as squames at the skin surface [4,5,6].
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