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PloS one2019; 14(9); e0219234; doi: 10.1371/journal.pone.0219234

The expression of equine keratins K42 and K124 is restricted to the hoof epidermal lamellae of Equus caballus.

Abstract: The equine hoof inner epithelium is folded into primary and secondary epidermal lamellae which increase the dermo-epidermal junction surface area of the hoof and can be affected by laminitis, a common disease of equids. Two keratin proteins (K), K42 and K124, are the most abundant keratins in the hoof lamellar tissue of Equus caballus. We hypothesize that these keratins are lamellar tissue-specific and could serve as differentiation- and disease-specific markers. Our objective was to characterize the expression of K42 and K124 in equine stratified epithelia and to generate monoclonal antibodies against K42 and K124. By RT-PCR analysis, keratin gene (KRT) KRT42 and KRT124 expression was present in lamellar tissue, but not cornea, haired skin, or hoof coronet. In situ hybridization studies showed that KRT124 localized to the suprabasal and, to a lesser extent, basal cells of the lamellae, was absent from haired skin and hoof coronet, and abruptly transitions from KRT124-negative coronet to KRT124-positive proximal lamellae. A monoclonal antibody generated against full-length recombinant equine K42 detected a lamellar keratin of the appropriate size, but also cross-reacted with other epidermal keratins. Three monoclonal antibodies generated against N- and C-terminal K124 peptides detected a band of the appropriate size in lamellar tissue and did not cross-react with proteins from haired skin, corneal limbus, hoof coronet, tongue, glabrous skin, oral mucosa, or chestnut on immunoblots. K124 localized to lamellar cells by indirect immunofluorescence. This is the first study to demonstrate the localization and expression of a hoof lamellar-specific keratin, K124, and to validate anti-K124 monoclonal antibodies.
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Publication Date: 2019-09-24 PubMed ID: 31550264PubMed Central: PMC6759161DOI: 10.1371/journal.pone.0219234Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research article investigates the restricted expression of two keratin proteins, K42 and K124, within the lamellar tissue of the equine hoof in horses. The study explores the possibility that these keratins serve as specific indicators for differentiation and disease within the hoof’s tissue as well as the development of monoclonal antibodies against these keratins.

Context and Motivation

  • The inner epithelium of a horse’s hoof folds into structures known as primary and secondary epidermal lamellae.
  • This structure increases the intersection of the epithelium and dermis, however, it is susceptible to a disease known as laminitis.
  • The lamellar tissue of the horse hoof abundantly expresses two types of keratin proteins K42 and K124.
  • The researchers propose the idea that these keratins might be specific to lamellar tissue and could serve as disease-specific markers and a determinant of cell differentiation.

Objective of the Research

  • The researchers’ primary goal was to understand the expression of K42 and K124 in the stratified epithelium of a horse’s hoof.
  • This investigation also aimed at generating monoclonal antibodies for K42 and K124 which may possibly serve as a diagnostic tool for hoof ailments in future.

Methodology

  • Keratin genes KRT42 and KRT124 were analyzed via RT-PCR to understand their expression patterns.
  • In-situ hybridization studies were conducted to localize KRT124 within the tissue layers of the hoof.
  • Monoclonal antibodies were generated against full-length recombinant equine K42 and K124 peptides to track their presence.

Results and Findings

  • Both KRT42 and KRT124 expressions were found only in the lamellar tissue and not in cornea, haired skin or hoof coronet.
  • KRT124 was localized primarily to the suprabasal layers of the lamellae and was not present in haired skin and hoof coronet.
  • The monoclonal antibodies, specifically those against K124 showed selective binding with lamellar tissue without crossing reacting with proteins from other tissues.

Conclusion

  • This is the first study that details the localization and expression patterns of a hoof lamellar-specific keratin, K124.
  • The study also confirms the validity of anti-K124 monoclonal antibodies and their potential in revealing the health status of the hoof lamellar tissue.

Cite This Article

APA
Armstrong C, Cassimeris L, Da Silva Santos C, Micoogullari Y, Wagner B, Babasyan S, Brooks S, Galantino-Homer H. (2019). The expression of equine keratins K42 and K124 is restricted to the hoof epidermal lamellae of Equus caballus. PLoS One, 14(9), e0219234. https://doi.org/10.1371/journal.pone.0219234

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 14
Issue: 9
Pages: e0219234

Researcher Affiliations

Armstrong, Caitlin
  • Department of Clinical Studies, New Bolton Center, University of Pennsylvania, School of Veterinary Medicine, Kennett Square, Pennsylvania, United States of America.
Cassimeris, Lynne
  • Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America.
Da Silva Santos, Claire
  • Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America.
Micoogullari, Yagmur
  • Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America.
Wagner, Bettina
  • Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.
Babasyan, Susanna
  • Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.
Brooks, Samantha
  • Department of Animal Sciences and University of Florida Genetics institute, University of Florida, Gainesville, Florida, United States of America.
Galantino-Homer, Hannah
  • Department of Clinical Studies, New Bolton Center, University of Pennsylvania, School of Veterinary Medicine, Kennett Square, Pennsylvania, United States of America.

MeSH Terms

  • Animals
  • Biomarkers
  • Epidermis / metabolism
  • Gene Expression
  • Hoof and Claw / anatomy & histology
  • Hoof and Claw / cytology
  • Hoof and Claw / metabolism
  • Horses
  • Immunohistochemistry
  • Keratins / genetics
  • Organ Specificity / genetics
  • Protein Isoforms
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism

Conflict of Interest Statement

A source of financial support for the archived samples used for this study, the Bernice Barbour Foundation, Inc., is considered a “commercial funder.” This does not alter our adherence to PLOS ONE policies on sharing data and materials. The Bernice Barbour Foundation, Inc. is a private tax-exempt philanthropic foundation and will not interfere with the full and objective presentation, peer review, editorial decision-making, or publication of this research article. This funding source does not place any restrictions on sharing of data and/or materials.

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Citations

This article has been cited 4 times.
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  2. Kalabusheva EP, Shtompel AS, Rippa AL, Ulianov SV, Razin SV, Vorotelyak EA. A Kaleidoscope of Keratin Gene Expression and the Mosaic of Its Regulatory Mechanisms. Int J Mol Sci 2023 Mar 15;24(6).
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  4. Cassimeris L, Engiles JB, Galantino-Homer H. Interleukin-17A pathway target genes are upregulated in Equus caballus supporting limb laminitis. PLoS One 2020;15(12):e0232920.
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