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A novel DLX3 – PKC integrated signaling network drives keratinocyte differentiation

View Article: PubMed Central - PubMed

ABSTRACT

Epidermal homeostasis relies on a well-defined transcriptional control of keratinocyte proliferation and differentiation, which is critical to prevent skin diseases such as atopic dermatitis, psoriasis or cancer. We have recently shown that the homeobox transcription factor DLX3 and the tumor suppressor p53 co-regulate cell cycle-related signaling and that this mechanism is functionally involved in cutaneous squamous cell carcinoma development. Here we show that DLX3 expression and its downstream signaling depend on protein kinase C α (PKCα) activity in skin. We found that following 12-O-tetradecanoyl-phorbol-13-acetate (TPA) topical treatment, DLX3 expression is significantly upregulated in the epidermis and keratinocytes from mice overexpressing PKCα by transgenic targeting (K5-PKCα), resulting in cell cycle block and terminal differentiation. Epidermis lacking DLX3 (DLX3cKO), which is linked to the development of a DLX3-dependent epidermal hyperplasia with hyperkeratosis and dermal leukocyte recruitment, displays enhanced PKCα activation, suggesting a feedback regulation of DLX3 and PKCα. Of particular significance, transcriptional activation of epidermal barrier, antimicrobial peptide and cytokine genes is significantly increased in DLX3cKO skin and further increased by TPA-dependent PKC activation. Furthermore, when inhibiting PKC activity, we show that epidermal thickness, keratinocyte proliferation and inflammatory cell infiltration are reduced and the PKC-DLX3-dependent gene expression signature is normalized. Independently of PKC, DLX3 expression specifically modulates regulatory networks such as Wnt signaling, phosphatase activity and cell adhesion. Chromatin immunoprecipitation sequencing analysis of primary suprabasal keratinocytes showed binding of DLX3 to the proximal promoter regions of genes associated with cell cycle regulation, and of structural proteins and transcription factors involved in epidermal differentiation. These results indicate that Dlx3 potentially regulates a set of crucial genes necessary during the epidermal differentiation process. Altogether, we demonstrate the existence of a robust DLX3–PKCα signaling pathway in keratinocytes that is crucial to epidermal differentiation control and cutaneous homeostasis.

No MeSH data available.


Related in: MedlinePlus

DLX3-dependent regulation of epidermal homeostasis-related signaling pathways. (a) Heatmaps showing the DLX3-dependent upregulation of the 'Regulation of Transcription' and 'Wnt Signaling' pathways between DLX3cKO and WT skin treated with GF109203X or acetone (control). Bottom: Heatmaps showing the DLX3-dependent downregulation of the 'Phosphatase Activity' and 'Cell Adhesion' signaling pathways between DLX3cKO and WT skin treated with TPA or GF109203X or acetone (control). Expression values are colored based on their z-score after normalization across treatments. (b) Schematic representation by Venny diagrams of the significantly upregulated (left) or downregulated (right) genes in DLX3cKO skin after treatment with GF109203X prior to TPA (GF-TPA), TPA or acetone (control). Top significant GO Biological Process (BP) terms are indicated in tables: GF-TPA unique (orange), TPA unique (light blue) and GF-TPA and TPA common (green)
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fig7: DLX3-dependent regulation of epidermal homeostasis-related signaling pathways. (a) Heatmaps showing the DLX3-dependent upregulation of the 'Regulation of Transcription' and 'Wnt Signaling' pathways between DLX3cKO and WT skin treated with GF109203X or acetone (control). Bottom: Heatmaps showing the DLX3-dependent downregulation of the 'Phosphatase Activity' and 'Cell Adhesion' signaling pathways between DLX3cKO and WT skin treated with TPA or GF109203X or acetone (control). Expression values are colored based on their z-score after normalization across treatments. (b) Schematic representation by Venny diagrams of the significantly upregulated (left) or downregulated (right) genes in DLX3cKO skin after treatment with GF109203X prior to TPA (GF-TPA), TPA or acetone (control). Top significant GO Biological Process (BP) terms are indicated in tables: GF-TPA unique (orange), TPA unique (light blue) and GF-TPA and TPA common (green)

Mentions: The analysis of differentially expressed genes between DLX3cKO and WT skin, both treated with TPA or GF, or untreated, allowed the identification of specific signaling pathways within cutaneous homeostasis whose regulation is DLX3 dependent and not linked to PKC activity (Figure 7a).


A novel DLX3 – PKC integrated signaling network drives keratinocyte differentiation
DLX3-dependent regulation of epidermal homeostasis-related signaling pathways. (a) Heatmaps showing the DLX3-dependent upregulation of the 'Regulation of Transcription' and 'Wnt Signaling' pathways between DLX3cKO and WT skin treated with GF109203X or acetone (control). Bottom: Heatmaps showing the DLX3-dependent downregulation of the 'Phosphatase Activity' and 'Cell Adhesion' signaling pathways between DLX3cKO and WT skin treated with TPA or GF109203X or acetone (control). Expression values are colored based on their z-score after normalization across treatments. (b) Schematic representation by Venny diagrams of the significantly upregulated (left) or downregulated (right) genes in DLX3cKO skin after treatment with GF109203X prior to TPA (GF-TPA), TPA or acetone (control). Top significant GO Biological Process (BP) terms are indicated in tables: GF-TPA unique (orange), TPA unique (light blue) and GF-TPA and TPA common (green)
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5384032&req=5

fig7: DLX3-dependent regulation of epidermal homeostasis-related signaling pathways. (a) Heatmaps showing the DLX3-dependent upregulation of the 'Regulation of Transcription' and 'Wnt Signaling' pathways between DLX3cKO and WT skin treated with GF109203X or acetone (control). Bottom: Heatmaps showing the DLX3-dependent downregulation of the 'Phosphatase Activity' and 'Cell Adhesion' signaling pathways between DLX3cKO and WT skin treated with TPA or GF109203X or acetone (control). Expression values are colored based on their z-score after normalization across treatments. (b) Schematic representation by Venny diagrams of the significantly upregulated (left) or downregulated (right) genes in DLX3cKO skin after treatment with GF109203X prior to TPA (GF-TPA), TPA or acetone (control). Top significant GO Biological Process (BP) terms are indicated in tables: GF-TPA unique (orange), TPA unique (light blue) and GF-TPA and TPA common (green)
Mentions: The analysis of differentially expressed genes between DLX3cKO and WT skin, both treated with TPA or GF, or untreated, allowed the identification of specific signaling pathways within cutaneous homeostasis whose regulation is DLX3 dependent and not linked to PKC activity (Figure 7a).

View Article: PubMed Central - PubMed

ABSTRACT

Epidermal homeostasis relies on a well-defined transcriptional control of keratinocyte proliferation and differentiation, which is critical to prevent skin diseases such as atopic dermatitis, psoriasis or cancer. We have recently shown that the homeobox transcription factor DLX3 and the tumor suppressor p53 co-regulate cell cycle-related signaling and that this mechanism is functionally involved in cutaneous squamous cell carcinoma development. Here we show that DLX3 expression and its downstream signaling depend on protein kinase C α (PKCα) activity in skin. We found that following 12-O-tetradecanoyl-phorbol-13-acetate (TPA) topical treatment, DLX3 expression is significantly upregulated in the epidermis and keratinocytes from mice overexpressing PKCα by transgenic targeting (K5-PKCα), resulting in cell cycle block and terminal differentiation. Epidermis lacking DLX3 (DLX3cKO), which is linked to the development of a DLX3-dependent epidermal hyperplasia with hyperkeratosis and dermal leukocyte recruitment, displays enhanced PKCα activation, suggesting a feedback regulation of DLX3 and PKCα. Of particular significance, transcriptional activation of epidermal barrier, antimicrobial peptide and cytokine genes is significantly increased in DLX3cKO skin and further increased by TPA-dependent PKC activation. Furthermore, when inhibiting PKC activity, we show that epidermal thickness, keratinocyte proliferation and inflammatory cell infiltration are reduced and the PKC-DLX3-dependent gene expression signature is normalized. Independently of PKC, DLX3 expression specifically modulates regulatory networks such as Wnt signaling, phosphatase activity and cell adhesion. Chromatin immunoprecipitation sequencing analysis of primary suprabasal keratinocytes showed binding of DLX3 to the proximal promoter regions of genes associated with cell cycle regulation, and of structural proteins and transcription factors involved in epidermal differentiation. These results indicate that Dlx3 potentially regulates a set of crucial genes necessary during the epidermal differentiation process. Altogether, we demonstrate the existence of a robust DLX3–PKCα signaling pathway in keratinocytes that is crucial to epidermal differentiation control and cutaneous homeostasis.

No MeSH data available.


Related in: MedlinePlus