J Vet Sci.  2012 Jun;13(2):163-170. 10.4142/jvs.2012.13.2.163.

Histologic morphology and involucrin, filaggrin, and keratin expression in normal canine skin from dogs of different breeds and coat types

• Theerawatanasirikul S
• Suriyaphol G
• Thanawongnuwech R
• Sailasuta

• KMID: 1376190
• DOI: http://doi.org/10.4142/jvs.2012.13.2.163

Abstract

The purpose of this study was to measure the thickness of canine epidermis at various anatomical sites according to localization of cornified envelopes (involucrin and filaggrin), keratins (keratin 10, 5), and their mRNA expression. This was done in the skin of five breeds of dogs including seven poodles, six golden retrievers, six Shih Tzus, four pugs, and four Labrador retrievers. Epidermal thickness of the stratum corneum and nucleated epidermal layer was significantly different. The greatest thickness was observed in the digital web area and the thinnest epidermis was in the axilla. Epidermal thickness was also significantly different between the breeds (p < 0.05). Immunohistochemical staining scores revealed significant decreases of involucrin, filaggrin, and keratin 10 in the ventral and weight-bearing sites, and a relative increase of keratin 5 (p < 0.05). q-PCR analysis showed that their the levels of mRNA were positively correlated with expression of the corresponding proteins in skin samples (p < 0.05). The present study is the first to report the relationship between epidermal gene expression and histologic morphology of the skin in normal dogs. Further studies will be essential to fully understand the pathogenesis of skin barrier dysfunctions in canines.

Keyword

dog; filaggrin; involucrin; keratins; skin

MeSH Terms

Animals
DNA, Complementary/genetics/metabolism
Dogs/anatomy & histology/genetics/*metabolism
Gene Expression Regulation/*physiology
Intermediate Filament Proteins/genetics/*metabolism
Keratin-10/genetics/*metabolism
Keratin-5/genetics/*metabolism
Polymerase Chain Reaction/methods/veterinary
Protein Precursors/genetics/*metabolism
RNA/genetics/metabolism
Skin/anatomy & histology/metabolism

Figure

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  Fig. 1 Total epidermal thickness according to stratum corneum (SC) and nucleated epidermal layers (µm) from 16 regions in 27 dogs. Solid lines and dash lines indicate significant differences in SC and nucleated epidermal layer, respectively. Data are expressed as the mean ± SD (*p < 0.05 and **p < 0.01).

• 

  Fig. 2 The average total epidermal thickness of all skin samples in five different breeds of dogs. Solid lines and dash lines indicate significant differences in SC and nucleated epidermal layer, respectively. Data are expressed as the mean ± SD (*p < 0.05 and **p < 0.01).

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  Fig. 3 Immunohistochemical localization of various proteins expressed in the epidermis of normal dog skin from the abdominal areas. A: involucrin, B: filaggrin, C: keratin 10, D: keratin 5. DAB and Meyer's hematoxylin counterstain, ×200. Scale bars = 25 µm.

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  Fig. 4 mRNA expression of involucrin, filaggrin, keratin 10, and keratin 5 in abdominal skin from five clinically normal poodles (lane 1~5). Lane M: 100 bp DNA ladder.

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  Fig. 5 mRNA was collected from the skin of dogs. The levels of involucrin, filaggrin, keratin 10, and keratin 5 expression were then evaluated by RT-PCR. Different symbols (*for involucrin, †for filaggrin, ‡for keratin 10, and §for keratin 5) indicate significant differences (p < 0.05) of each target gene.

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