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In vivo and in vitro evidence for autocrine DCoH/HNF‐1α transcription of albumin in the human epidermis
Author(s) -
Hasse S.,
Kothari S.,
Rokos H.,
Kauser S.,
Schürer N. Y.,
Schallreuter K. U.
Publication year - 2005
Publication title -
experimental dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 96
eISSN - 1600-0625
pISSN - 0906-6705
DOI - 10.1111/j.0906-6705.2005.00265.x
Subject(s) - epidermis (zoology) , in vivo , keratinocyte , albumin , microbiology and biotechnology , human skin , biology , in vitro , hacat , dermis , paracrine signalling , autocrine signalling , chemistry , biochemistry , receptor , anatomy , genetics
The presence of albumin in the human epidermis has been reported more than a decade ago, but until now, it was assumed that this protein is synthesized in the liver and transported to the avascular skin. To our knowledge, transcription of albumin in the human epidermis was never considered. In this report, we present for the first time evidence for autocrine synthesis of albumin in the human epidermis in keratinocytes in situ and in vitro . Using double immunofluorescence labelling, we identified that albumin colocalized together with its transcription factor PCD/DCoH/HNF‐1α in suprabasal keratinocytes in human full‐thickness skin sections and in keratinocytes cultured in serum‐free medium. Moreover, albumin and HNF‐1α protein expression was confirmed by Western blotting in undifferentiated and differentiated keratinocytes as well as in human epidermal suction blister roof extracts. Reverse‐transcriptase polymerase chain reaction analysis from human epidermal keratinocytes and epidermal suction blister roofs revealed the transcription of albumin. Using in vivo fluorescence excitation spectroscopy at the surface of human skin, we confirmed albumin as a major constituent yielding a λ max at 295 nm, which was assigned to the single tryptophan 214 fluorophore in this protein. This in vivo result is in agreement with albumin concentrations of 10 −3 M, underlining the importance of this protein in epidermal homeostasis.