1. Suppression of Vitamin D Receptor and Induction of Retinoid X Receptor α Expression During Squamous Differentiation of Cultured Keratinocytes 
Siegfried Segaert, Marjan Garmyn, Hugo Degreef, Roger Bouillon 
Journal of Investigative Dermatology 
Volume 114, Issue 3, Pages (March 2000)
DOI: /j x
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

2. Figure 1
Suppression of VDR and induction of RXRα expression in cell density arrested keratinocytes. (a) Normal human keratinocytes were grown in keratinocyte serum-free medium (calcium 0.09 mM) and total RNA was isolated at 80% confluence or at the indicated time (in d) after confluence was reached. Northern blotting was performed by sequential hybridization with labeled probes for VDR, RXRα, cyclin D1 (Cy D1), c-myc, p21WAF1, transglutaminase I (Tgase I), SPR 1, SPR 2, and 18S RNA. (b) Total protein extracts were subjected to immunoblotting followed by detection of VDR, RXRα, and β-actin with specific antibodies as specified under Materials and Methods. (c) Densitometric quantification of VDR (or RXRα) mRNA (and protein) levels normalized for 18S (or actin) levels. Data are expressed as mean (SEM) of four scannings. The letter and the figure refer to the blot and the lane, respectively.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

3. Figure 2
EGF and KGF prevent downregulation of VDR in postconfluent keratinocytes. Primary keratinocytes at 80% confluence (lane 1) were grown to 4 d (a) or 6 d (b) postconfluence in the absence (lane 2) or presence of 50 ng EGF per ml (lane 3) or 10 ng KGF per ml (lane 4). Northern blot analysis (a) or western blot analysis (b) was carried out to reveal the indicated mRNAs or proteins. Densitometric data are shown in (c) as for Figure 1.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

4. Figure 3
Decreased VDR protein and induction of RXRα after calcium switch in human keratinocytes. The extracellular calcium concentration was raised from 0.09 to 1.8 mM for the indicated time in 40% confluent normal human epidermal keratinocytes. Northern blot analysis (a) or western blot analysis (b) was carried out to visualize the indicated mRNAs or proteins. Densitometric findings normalized for glyceraldehyde-3-phosphate dehydrogenase or actin are shown under (c) as for Figure 1.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

5. Figure 4
TPA suppresses VDR expression in keratinocytes. Eighty percent confluent keratinocytes were treated with TPA (100 ng per ml) for the indicated time. Total RNA or protein samples were used for northern blot analysis (a) or western blot analysis (b) to determine mRNA or protein levels of the investigated nuclear receptors and proliferation and differentiation markers. Normalized densitometric findings as for Figure 1 are shown in (c).
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

6. Figure 5
Downregulation of VDR and upregulation of RXRα in IFN-γ-treated cells. IFN-γ was added at a concentration of 200 units per ml to preconfluent primary keratinocytes for the time shown. The indicated mRNAs or proteins were visualized by northern blot (a) or western blot (b) analysis and quantified in (c) as for Figure 1.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions

7. Figure 6
Vitamin D responsiveness in keratinocytes is reduced by postconfluence, high calcium, and TPA, but not by IFN-γ. (a) Cells were treated for 24 h with 1,25(OH)2D3 (1 or 0.1 μM) at preconfluence, at 4 d postconfluence, or at 4 d after a calcium switch. Total RNA samples were used for northern blot to detect 24-hydroxylase (24OHase) mRNA levels. (b) Untreated keratinocytes or keratinocytes treated with TPA (100 ng per ml) for 10 h or treated with IFN-γ (200 units per ml) for 72 h were stimulated for 16 h with calcitriol (0.1 or 0.04 μM). Northern blot of RNA samples revealed 24-hydroxylase mRNA. (c) Densitometric analysis of 24-hydroxylase mRNA levels normalized for 18S expressed as mean (SEM) of four scannings.
Journal of Investigative Dermatology  , DOI: ( /j x)
Copyright © 2000 The Society for Investigative Dermatology, Inc Terms and Conditions