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The vitamin D receptor is a Wnt effector that controls hair follicle differentiation and specifies tumor type in adult epidermis.

Pálmer HG, Anjos-Afonso F, Carmeliet G, Takeda H, Watt FM - PLoS ONE (2008)

Bottom Line: We have investigated how Wnt and vitamin D receptor signals regulate epidermal differentiation.The VDR is required for beta-catenin induced hair follicle formation in adult epidermis, and the vitamin D analog EB1089 synergizes with beta-catenin to stimulate hair differentiation.We conclude that VDR is a TCF/Lef-independent transcriptional effector of the Wnt pathway and that vitamin D analogues have therapeutic potential in tumors with inappropriate activation of Wnt signalling.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre, Cambridge, United Kingdom.

ABSTRACT
We have investigated how Wnt and vitamin D receptor signals regulate epidermal differentiation. Many epidermal genes induced by beta-catenin, including the stem cell marker keratin 15, contain vitamin D response elements (VDREs) and several are induced independently of TCF/Lef. The VDR is required for beta-catenin induced hair follicle formation in adult epidermis, and the vitamin D analog EB1089 synergizes with beta-catenin to stimulate hair differentiation. Human trichofolliculomas (hair follicle tumours) are characterized by high nuclear beta-catenin and VDR, whereas infiltrative basal cell carcinomas (BCCs) have high beta-catenin and low VDR levels. In mice, EB1089 prevents beta-catenin induced trichofolliculomas, while in the absence of VDR beta-catenin induces tumours resembling BCCs. We conclude that VDR is a TCF/Lef-independent transcriptional effector of the Wnt pathway and that vitamin D analogues have therapeutic potential in tumors with inappropriate activation of Wnt signalling.

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Ligand activated VDR-β-catenin complexes regulate transcription of hair follicle genes.(A–D) Cells were treated for 4 h (B–D) or 8 h (a) with (+) or without (−) Wnt3A or EB1089. (A) mRNA levels of the genes indicated were measured by real-time PCR. All values are represented as fold increase relative to wild type cells treated with vehicle alone. Data are means±S.D. of triplicate samples. (B–D) Wild type cells were lysed and immunoprecipitated with VDR, β-catenin, Lef1 or unrelated antibody (HA tag; UR). Immunoprecipitated genomic DNA fragments or input controls were amplified by real-time PCR using specific primers for three regions of the mouse promoters indicated or unrelated genomic primers (UR). Data are means±S.D. of triplicate samples. Scaled diagrams summarize location of VDREs and TCF/Lef binding sites and the proteins bound to each region in cells treated with Wnt3A and EB1089.
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pone-0001483-g002: Ligand activated VDR-β-catenin complexes regulate transcription of hair follicle genes.(A–D) Cells were treated for 4 h (B–D) or 8 h (a) with (+) or without (−) Wnt3A or EB1089. (A) mRNA levels of the genes indicated were measured by real-time PCR. All values are represented as fold increase relative to wild type cells treated with vehicle alone. Data are means±S.D. of triplicate samples. (B–D) Wild type cells were lysed and immunoprecipitated with VDR, β-catenin, Lef1 or unrelated antibody (HA tag; UR). Immunoprecipitated genomic DNA fragments or input controls were amplified by real-time PCR using specific primers for three regions of the mouse promoters indicated or unrelated genomic primers (UR). Data are means±S.D. of triplicate samples. Scaled diagrams summarize location of VDREs and TCF/Lef binding sites and the proteins bound to each region in cells treated with Wnt3A and EB1089.

Mentions: We next examined whether β-catenin acted as a transcriptional co-activator of VDR on a natural promoter. Keratin 15 is expressed by stem cells in the HF bulge and in β-catenin induced ectopic HF [5]. EB1089, but not Wnt3A, induced a luciferase reporter gene under the control of the mouse K15 promoter (proximal 5 kb) (Figure 1E). The highest induction occurred on combined treatment with EB1089 and Wnt3A. In VDR cells the keratin 15 promoter was unresponsive. Transfection of an exogenous wild type VDR rescued the response to EB1089 and Wnt3A. We also performed real time PCR to investigate whether endogenous keratin 15 expression was modulated by vitamin D (Figure 2A). Wnt3A alone was unable to increase Krt15 mRNA levels in cultured wild type keratinocytes. However, EB1089 stimulated expression, and this effect was enhanced by Wnt3A in wild type but not in VDR or ΔNLef1 cells (Figure 2A). We conclude that β-catenin acts as a transcriptional co-activator of the VDR on both artificial (Figure 1C–E) and endogenous promoters.


The vitamin D receptor is a Wnt effector that controls hair follicle differentiation and specifies tumor type in adult epidermis.

Pálmer HG, Anjos-Afonso F, Carmeliet G, Takeda H, Watt FM - PLoS ONE (2008)

Ligand activated VDR-β-catenin complexes regulate transcription of hair follicle genes.(A–D) Cells were treated for 4 h (B–D) or 8 h (a) with (+) or without (−) Wnt3A or EB1089. (A) mRNA levels of the genes indicated were measured by real-time PCR. All values are represented as fold increase relative to wild type cells treated with vehicle alone. Data are means±S.D. of triplicate samples. (B–D) Wild type cells were lysed and immunoprecipitated with VDR, β-catenin, Lef1 or unrelated antibody (HA tag; UR). Immunoprecipitated genomic DNA fragments or input controls were amplified by real-time PCR using specific primers for three regions of the mouse promoters indicated or unrelated genomic primers (UR). Data are means±S.D. of triplicate samples. Scaled diagrams summarize location of VDREs and TCF/Lef binding sites and the proteins bound to each region in cells treated with Wnt3A and EB1089.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2198947&req=5

pone-0001483-g002: Ligand activated VDR-β-catenin complexes regulate transcription of hair follicle genes.(A–D) Cells were treated for 4 h (B–D) or 8 h (a) with (+) or without (−) Wnt3A or EB1089. (A) mRNA levels of the genes indicated were measured by real-time PCR. All values are represented as fold increase relative to wild type cells treated with vehicle alone. Data are means±S.D. of triplicate samples. (B–D) Wild type cells were lysed and immunoprecipitated with VDR, β-catenin, Lef1 or unrelated antibody (HA tag; UR). Immunoprecipitated genomic DNA fragments or input controls were amplified by real-time PCR using specific primers for three regions of the mouse promoters indicated or unrelated genomic primers (UR). Data are means±S.D. of triplicate samples. Scaled diagrams summarize location of VDREs and TCF/Lef binding sites and the proteins bound to each region in cells treated with Wnt3A and EB1089.
Mentions: We next examined whether β-catenin acted as a transcriptional co-activator of VDR on a natural promoter. Keratin 15 is expressed by stem cells in the HF bulge and in β-catenin induced ectopic HF [5]. EB1089, but not Wnt3A, induced a luciferase reporter gene under the control of the mouse K15 promoter (proximal 5 kb) (Figure 1E). The highest induction occurred on combined treatment with EB1089 and Wnt3A. In VDR cells the keratin 15 promoter was unresponsive. Transfection of an exogenous wild type VDR rescued the response to EB1089 and Wnt3A. We also performed real time PCR to investigate whether endogenous keratin 15 expression was modulated by vitamin D (Figure 2A). Wnt3A alone was unable to increase Krt15 mRNA levels in cultured wild type keratinocytes. However, EB1089 stimulated expression, and this effect was enhanced by Wnt3A in wild type but not in VDR or ΔNLef1 cells (Figure 2A). We conclude that β-catenin acts as a transcriptional co-activator of the VDR on both artificial (Figure 1C–E) and endogenous promoters.

Bottom Line: We have investigated how Wnt and vitamin D receptor signals regulate epidermal differentiation.The VDR is required for beta-catenin induced hair follicle formation in adult epidermis, and the vitamin D analog EB1089 synergizes with beta-catenin to stimulate hair differentiation.We conclude that VDR is a TCF/Lef-independent transcriptional effector of the Wnt pathway and that vitamin D analogues have therapeutic potential in tumors with inappropriate activation of Wnt signalling.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research UK Cambridge Research Institute, Li Ka Shing Centre, Cambridge, United Kingdom.

ABSTRACT
We have investigated how Wnt and vitamin D receptor signals regulate epidermal differentiation. Many epidermal genes induced by beta-catenin, including the stem cell marker keratin 15, contain vitamin D response elements (VDREs) and several are induced independently of TCF/Lef. The VDR is required for beta-catenin induced hair follicle formation in adult epidermis, and the vitamin D analog EB1089 synergizes with beta-catenin to stimulate hair differentiation. Human trichofolliculomas (hair follicle tumours) are characterized by high nuclear beta-catenin and VDR, whereas infiltrative basal cell carcinomas (BCCs) have high beta-catenin and low VDR levels. In mice, EB1089 prevents beta-catenin induced trichofolliculomas, while in the absence of VDR beta-catenin induces tumours resembling BCCs. We conclude that VDR is a TCF/Lef-independent transcriptional effector of the Wnt pathway and that vitamin D analogues have therapeutic potential in tumors with inappropriate activation of Wnt signalling.

Show MeSH
Related in: MedlinePlus