Claudin 2 mRNA and protein are present in human keratinocytes and may be regulated by all-trans-retinoic acid.
Tight junctions are composed of claudins, occludins, junctional adhesion molecules and plaque proteins. Claudin 2 protein forms a cation-selective channel which confers increased permeability in renal epithelial cells and in the intestine where its expression is restricted to the leaky epithelium. Immunohistochemical staining revealed claudin 2 staining in the granular layer of adult epidermis. Analysis of Western blots revealed bands corresponding to the molecular weight of claudin 2 in Madin-Darby canine kidney II cells, human kidney, adult skin and neonatal keratinocytes. Reverse transcriptase polymerase chain reaction on mRNA and cDNA sequence analysis found a 99% sequence homology between our cDNA and human claudin 2 (NIH BLAST sequence). Further, we show that all-trans-retinoic acid increases the expression of claudin 2 in keratinocytes in a dose-dependent manner. The discovery of claudin 2 transcript and protein in the skin could be of importance in epidermal differentiation, barrier function and pathological conditions.
DFB Branded Pharmaceuticals, Central Research Division, Fort Worth, Tex. 76017, USA. Dale.Telgenhoff@dfb.com
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Telgenhoff
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Ramsay
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Hilz
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Slusarewicz
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Shroot
D000328:Adult; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D057167:Claudins; D004285:Dogs; D004817:Epidermis / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007231:Infant, Newborn; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D010539:Permeability; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*
C491875:CLDN2 protein, human; D057167:Claudins; D008565:Membrane Proteins; D012333:RNA, Messenger; D014212:Tretinoin