title: Expression and localization of epithelial stem cell and differentiation markers in equine skin, eye and hoof.
abstract: BACKGROUND
  The limited characterization of equine skin, eye and hoof epithelial stem cell (ESC) and differentiation markers impedes the investigation of the physiology and pathophysiology of these tissues.
  
  
  OBJECTIVE
  To characterize ESC and differentiation marker expression in epithelial tissues of the equine eye, haired skin and hoof capsule.
  
  
  METHODS
  Indirect immunofluorescence microscopy and immunoblotting were used to detect expression and tissue localization of keratin (K) isoforms K3, K10, K14 and K124, the transcription factor p63 (a marker of ESCs) and phosphorylated p63 [pp63; a marker of ESC transition to transit-amplifying (TA) cell] in epithelial tissues of the foot (haired skin, hoof coronet and hoof lamellae) and the eye (limbus and cornea).
  
  
  RESULTS
  Expression of K14 was restricted to the basal layer of epidermal lamellae and to basal and adjacent suprabasal layers of the haired skin, coronet and corneal limbus. Coronary and lamellar epidermis was negative for both K3 and K10, which were expressed in the cornea/limbus epithelium and haired skin epidermis, respectively. Variable expression of p63 with relatively low to high levels of phosphorylation was detected in individual basal and suprabasal cells of all epithelial tissues examined.
  
  
  CONCLUSIONS
  To the best of the author's knowledge, this is the first report of the characterization of tissue-specific keratin marker expression and the localization of putative epithelial progenitor cell populations, including ESCs (high p63 expression with low pp63 levels) and TA cells (high expression of both p63 and pp63), in the horse. These results will aid further investigation of epidermal and corneal epithelial biology and regenerative therapies in horses.
authors.affiliation: Department of Clinical Studies, New Bolton Center, 382 West Street Road, Kennett Square, PA, 19348, USA.
authors.forename: Renata L
authors.initials: RL
authors.lastname: Linardi
authors.affiliation: Department of Clinical Studies, New Bolton Center, 382 West Street Road, Kennett Square, PA, 19348, USA.
authors.forename: Susan O
authors.initials: SO
authors.lastname: Megee
authors.affiliation: Department of Clinical Studies, New Bolton Center, 382 West Street Road, Kennett Square, PA, 19348, USA.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Mainardi
authors.affiliation: Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, 3800 Spruce Street, Philadelphia, PA, 19104, USA.
authors.forename: Makoto
authors.initials: M
authors.lastname: Senoo
authors.affiliation: Department of Clinical Studies, New Bolton Center, 382 West Street Road, Kennett Square, PA, 19348, USA.
authors.forename: Hannah L
authors.initials: HL
authors.lastname: Galantino-Homer
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D003315:Cornea / Q000166:cytology* / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006724:Hoof and Claw / Q000166:cytology* / Q000378:metabolism; D006736:Horses / Q000033:anatomy & histology* / Q000378:metabolism; D015151:Immunoblotting; D007633:Keratins / Q000378:metabolism; D008297:Male; D012867:Skin / Q000166:cytology* / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism / Q000502:physiology*
chemical_list: D000943:Antigens, Differentiation; D007633:Keratins