title: The differential expression of protease activated receptors contributes to functional differences between dark and fair keratinocytes.
abstract: BACKGROUND
  Dark skin has different properties in comparison to fair skin. Melanocytes have been shown to partly contribute to these differences, however, the involvement of keratinocytes from dark or fair skin is not well demonstrated.
  
  
  OBJECTIVE
  This study investigated the proliferation and barrier function of dark keratinocytes (DK) and fair keratinocytes (FK), and the role of protease activated receptor (PAR)1 and PAR2.
  
  
  METHODS
  DK and FK were isolated from human neonatal foreskins. Cells were treated with PAR1/PAR2 agonists or antagonists, proliferation was measured by BrdU assay; permeability by the flux of FITC-dextran; protein expression by immunostaining or western blot.
  
  
  RESULTS
  When compared to FK, DK proliferated significantly slower; had higher cell permeability; expressed less phosphorylated (P)-ERK/ERK, caspase-14, E-cadherin, tissue growth factor (TGF)-β3 and PAR1; and expressed more PAR2, and matrix metalloproteinase (MMP)-9. Activation of PAR1 or inhibition of PAR2 stimulated cell proliferation and ERK activation, and in concordance inhibition of PAR1 or activation of PAR2 suppressed cell proliferation and ERK activation in both DK and FK. Inhibition of PAR2 decreased and inhibition of PAR1 increased cell permeability. In foreskin sections, the epidermis of dark foreskin expressed less caspase-14 and the same level but different distribution of E-cadherin, when compared to fair foreskin.
  
  
  CONCLUSIONS
  These data highlight functional differences in proliferation and barrier integrity between HK and FK that are partly associated with their differential expression of PAR1 and PAR2.
authors.affiliation: Sutton Research Laboratory, Kolling Institute of Medical Research, the University of Sydney at Royal North Shore Hospital, St Leonard NSW 2065 Australia.
authors.forename: Meilang
authors.initials: M
authors.lastname: Xue
authors.affiliation: Sutton Research Laboratory, Kolling Institute of Medical Research, the University of Sydney at Royal North Shore Hospital, St Leonard NSW 2065 Australia. Electronic address: meilang.xue@sydney.edu.au.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Lin
authors.affiliation: Sutton Research Laboratory, Kolling Institute of Medical Research, the University of Sydney at Royal North Shore Hospital, St Leonard NSW 2065 Australia.
authors.forename: Ruilong
authors.initials: R
authors.lastname: Zhao
authors.affiliation: Sutton Research Laboratory, Kolling Institute of Medical Research, the University of Sydney at Royal North Shore Hospital, St Leonard NSW 2065 Australia.
authors.forename: Hai Po Helena
authors.initials: HP
authors.lastname: Liang
authors.affiliation: Sutton Research Laboratory, Kolling Institute of Medical Research, the University of Sydney at Royal North Shore Hospital, St Leonard NSW 2065 Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Jackson
mesh_terms: D015703:Antigens, CD; D015820:Cadherins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002463:Cell Membrane Permeability; D049109:Cell Proliferation; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D000078404:Epidermal Cells; D005455:Fluorescent Antibody Technique; D006801:Humans; D015603:Keratinocytes / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D010766:Phosphorylation; D044463:Receptor, PAR-1 / Q000819:agonists / Q000378:metabolism*; D044464:Receptor, PAR-2 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012880:Skin Pigmentation / Q000502:physiology*; D053782:Transforming Growth Factor beta3 / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; C509044:TGFB3 protein, human; D053782:Transforming Growth Factor beta3; C506446:CASP14 protein, human; D020169:Caspases; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9; D010975:Platelet Aggregation Inhibitors
keywords: Barrier function; Dark or fair skin; Keratinocyte; Proliferation; Protease activated receptor