Rb. Presland et al., Regulation of human profilaggrin promoter activity in cultured epithelial cells by retinoic acid and glucocorticoids, J DERMA SCI, 27(3), 2001, pp. 192-205
Vitamin A and other retinoids profoundly inhibit both morphological and bio
chemical aspects of epidermal differentiation in vitro. Profilaggrin, like
most other markers of keratinocyte differentiation, is negatively regulated
by retinoic acid in vitro, both at the level of mRNA synthesis and by inhi
biting the activity of endoproteases that convert profilaggrin to filaggrin
. Profilaggrin is an abundant component of keratohyalin granules and forms
the precursor of filaggrin, the keratin associated protein of the stratum c
orneum. In this report, we identify a region of the human profilaggrin prom
oter that is involved in the transcriptional regulation of expression by re
tinoic acid (RA). A series of promoter deletions linked to the chlorampheni
col acetyl transferase (CAT) reporter gene were prepared and analyzed by tr
ansfection into Hela cells and keratinocytes. We also cotransfected vectors
expressing retinoic acid receptor and cultured the transfected cells in th
e presence and absence of ligand. The region responsive to retinoic acid wa
s localized to a 53 bp sequence between - 1109 and - 1056 (relative to the
mRNA start site at + 1) that contains a cluster of five retinoic acid respo
nse elements with variable spacing and orientation. In vitro gel shift anal
ysis demonstrated that nuclear retinoid receptors do not bind directly to t
he identified sequence, suggesting that the mode of regulation by RA may be
indirect or that binding requires another cofactor in addition to retinoid
receptors. Whereas in keratin genes retinoic acid and glucocorticoid respo
nsive sequences frequently coincide, the glucocorticoid response element in
the profilaggrin promoter was located downstream of the RARE cluster betwe
en - 965 and - 951. These studies demonstrate that RA and glucocorticoids r
egulate profilaggrin expression at least in part by transcriptional mechani
sms, via a region of the promoter that contains both retinoid and glucocort
icoid responsive elements. (C) 2001 Elsevier Science Ireland Ltd. All right
s reserved.