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Plakoglobin as a regulator of desmocollin gene expression.

Tokonzaba E, Chen J, Cheng X, Den Z, Ganeshan R, Műller EJ, Koch PJ - J. Invest. Dermatol. (2013)

Bottom Line: Specifically, we found that Lef-1 acts as a switch activating Dsc2 and repressing Dsc3 in the presence of Pg.Interestingly, we also determined that NF-κB pathway components, the downstream effectors of the ectodysplasin-A (EDA)/ ectodysplasin-A receptor (EDAR)/NF-κB signaling cascade, can activate Dsc2 expression.It is tempting to speculate that this shift is required for the invasive growth of placode keratinocytes into the dermis, a crucial step in skin appendage formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, University of Colorado School of Medicine, Aurora, Colorado, USA.

ABSTRACT
Desmosomes are cell adhesion junctions required for the normal development and maintenance of mammalian tissues and organs such as the skin, skin appendages, and the heart. The goal of this study was to investigate how desmocollins (DSCs), transmembrane components of desmosomes, are regulated at the transcriptional level. We hypothesized that differential expression of the Dsc2 and Dsc3 genes is a prerequisite for normal development of skin appendages. We demonstrate that plakoglobin (Pg) in conjunction with lymphoid enhancer-binding factor 1 (Lef-1) differentially regulates the proximal promoters of these two genes. Specifically, we found that Lef-1 acts as a switch activating Dsc2 and repressing Dsc3 in the presence of Pg. Interestingly, we also determined that NF-κB pathway components, the downstream effectors of the ectodysplasin-A (EDA)/ ectodysplasin-A receptor (EDAR)/NF-κB signaling cascade, can activate Dsc2 expression. We hypothesize that Lef-1 and EDA/EDAR/NF-κB signaling contribute to a shift in Dsc isoform expression from Dsc3 to Dsc2 in placode keratinocytes. It is tempting to speculate that this shift is required for the invasive growth of placode keratinocytes into the dermis, a crucial step in skin appendage formation.

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Identification and functional characterization of TCF/Lef factor-binding sites in the Dsc2 and Dsc3 promoters(a-b). Schematic representation of putative transcription factor binding sites in the proximal Dsc promoters. The arrows indicate translation start sites (ATG; A is defined as position +1). The DNA sequences of wild type (Wt) and mutant (Mut) transcription factor binding sites are shown. (c-d) ChIP assays demonstrating TCF/Lef binding to the predicted target sites in the Dsc promoters. Note that the point mutations introduced into the TCF/Lef target sequences (Dsc2 Mut, Dsc3 Mut) abrogate binding of the transcription factors. Input, chromatin used for immunoprecipitation; IgG, IP with unspecific IgG. (e-f) Reporter assays in mouse keratinocytes. Note that inactivation of the TCF/Lef binding sites in the Dsc3 construct increases reporter activity significantly. Error bars, standard deviation. Star indicates a statistically significant result (p-value < 0.05).
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Figure 1: Identification and functional characterization of TCF/Lef factor-binding sites in the Dsc2 and Dsc3 promoters(a-b). Schematic representation of putative transcription factor binding sites in the proximal Dsc promoters. The arrows indicate translation start sites (ATG; A is defined as position +1). The DNA sequences of wild type (Wt) and mutant (Mut) transcription factor binding sites are shown. (c-d) ChIP assays demonstrating TCF/Lef binding to the predicted target sites in the Dsc promoters. Note that the point mutations introduced into the TCF/Lef target sequences (Dsc2 Mut, Dsc3 Mut) abrogate binding of the transcription factors. Input, chromatin used for immunoprecipitation; IgG, IP with unspecific IgG. (e-f) Reporter assays in mouse keratinocytes. Note that inactivation of the TCF/Lef binding sites in the Dsc3 construct increases reporter activity significantly. Error bars, standard deviation. Star indicates a statistically significant result (p-value < 0.05).

Mentions: DNA sequence analysis revealed the presence of putative TCF/Lef (Figure 1a-b) and NFκB (see below) target sites in the Dsc2 and Dsc3 promoters. Considering that the Wnt pathway, which affects gene expression via catenin/TCF/Lef transcription factors, and the NFκB pathways have been shown to play major roles in HF formation, we decided to focus on the role of these two signaling cascades in Dsc gene regulation.


Plakoglobin as a regulator of desmocollin gene expression.

Tokonzaba E, Chen J, Cheng X, Den Z, Ganeshan R, Műller EJ, Koch PJ - J. Invest. Dermatol. (2013)

Identification and functional characterization of TCF/Lef factor-binding sites in the Dsc2 and Dsc3 promoters(a-b). Schematic representation of putative transcription factor binding sites in the proximal Dsc promoters. The arrows indicate translation start sites (ATG; A is defined as position +1). The DNA sequences of wild type (Wt) and mutant (Mut) transcription factor binding sites are shown. (c-d) ChIP assays demonstrating TCF/Lef binding to the predicted target sites in the Dsc promoters. Note that the point mutations introduced into the TCF/Lef target sequences (Dsc2 Mut, Dsc3 Mut) abrogate binding of the transcription factors. Input, chromatin used for immunoprecipitation; IgG, IP with unspecific IgG. (e-f) Reporter assays in mouse keratinocytes. Note that inactivation of the TCF/Lef binding sites in the Dsc3 construct increases reporter activity significantly. Error bars, standard deviation. Star indicates a statistically significant result (p-value < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3760975&req=5

Figure 1: Identification and functional characterization of TCF/Lef factor-binding sites in the Dsc2 and Dsc3 promoters(a-b). Schematic representation of putative transcription factor binding sites in the proximal Dsc promoters. The arrows indicate translation start sites (ATG; A is defined as position +1). The DNA sequences of wild type (Wt) and mutant (Mut) transcription factor binding sites are shown. (c-d) ChIP assays demonstrating TCF/Lef binding to the predicted target sites in the Dsc promoters. Note that the point mutations introduced into the TCF/Lef target sequences (Dsc2 Mut, Dsc3 Mut) abrogate binding of the transcription factors. Input, chromatin used for immunoprecipitation; IgG, IP with unspecific IgG. (e-f) Reporter assays in mouse keratinocytes. Note that inactivation of the TCF/Lef binding sites in the Dsc3 construct increases reporter activity significantly. Error bars, standard deviation. Star indicates a statistically significant result (p-value < 0.05).
Mentions: DNA sequence analysis revealed the presence of putative TCF/Lef (Figure 1a-b) and NFκB (see below) target sites in the Dsc2 and Dsc3 promoters. Considering that the Wnt pathway, which affects gene expression via catenin/TCF/Lef transcription factors, and the NFκB pathways have been shown to play major roles in HF formation, we decided to focus on the role of these two signaling cascades in Dsc gene regulation.

Bottom Line: Specifically, we found that Lef-1 acts as a switch activating Dsc2 and repressing Dsc3 in the presence of Pg.Interestingly, we also determined that NF-κB pathway components, the downstream effectors of the ectodysplasin-A (EDA)/ ectodysplasin-A receptor (EDAR)/NF-κB signaling cascade, can activate Dsc2 expression.It is tempting to speculate that this shift is required for the invasive growth of placode keratinocytes into the dermis, a crucial step in skin appendage formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, University of Colorado School of Medicine, Aurora, Colorado, USA.

ABSTRACT
Desmosomes are cell adhesion junctions required for the normal development and maintenance of mammalian tissues and organs such as the skin, skin appendages, and the heart. The goal of this study was to investigate how desmocollins (DSCs), transmembrane components of desmosomes, are regulated at the transcriptional level. We hypothesized that differential expression of the Dsc2 and Dsc3 genes is a prerequisite for normal development of skin appendages. We demonstrate that plakoglobin (Pg) in conjunction with lymphoid enhancer-binding factor 1 (Lef-1) differentially regulates the proximal promoters of these two genes. Specifically, we found that Lef-1 acts as a switch activating Dsc2 and repressing Dsc3 in the presence of Pg. Interestingly, we also determined that NF-κB pathway components, the downstream effectors of the ectodysplasin-A (EDA)/ ectodysplasin-A receptor (EDAR)/NF-κB signaling cascade, can activate Dsc2 expression. We hypothesize that Lef-1 and EDA/EDAR/NF-κB signaling contribute to a shift in Dsc isoform expression from Dsc3 to Dsc2 in placode keratinocytes. It is tempting to speculate that this shift is required for the invasive growth of placode keratinocytes into the dermis, a crucial step in skin appendage formation.

Show MeSH
Related in: MedlinePlus