title: A novel DLX3-PKC integrated signaling network drives keratinocyte differentiation.
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.
authors.affiliation: Laboratory of Skin Biology, NIAMS, NIH, Bethesda, MD 20892, USA.
authors.forename: Elisabetta
authors.identifier: 0000-0002-0812-5524
authors.initials: E
authors.lastname: Palazzo
authors.affiliation: Laboratory of Skin Biology, NIAMS, NIH, Bethesda, MD 20892, USA.
authors.forename: Meghan D
authors.initials: MD
authors.lastname: Kellett
authors.affiliation: Laboratory of Cancer Biology and Genetics, NCI, NIH, Bethesda, MD 20892, USA.
authors.forename: Christophe
authors.initials: C
authors.lastname: Cataisson
authors.affiliation: Laboratory of Skin Biology, NIAMS, NIH, Bethesda, MD 20892, USA.
authors.forename: Paul W
authors.identifier: 0000-0001-9969-4492
authors.initials: PW
authors.lastname: Bible
authors.affiliation: Laboratory of Skin Biology, NIAMS, NIH, Bethesda, MD 20892, USA.
authors.forename: Shreya
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Biodata Mining and Discovery Section, NIAMS, NIH, Bethesda, MD 20892, USA.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Sun
authors.affiliation: Laboratory of Skin Biology, NIAMS, NIH, Bethesda, MD 20892, USA.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Gormley
authors.affiliation: Laboratory of Cancer Biology and Genetics, NCI, NIH, Bethesda, MD 20892, USA.
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Yuspa
authors.affiliation: Laboratory of Skin Biology, NIAMS, NIH, Bethesda, MD 20892, USA.
authors.forename: Maria I
authors.initials: MI
authors.lastname: Morasso
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004817:Epidermis / Q000473:pathology / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006965:Hyperplasia; D007211:Indoles / Q000494:pharmacology; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D007962:Leukocytes / Q000166:cytology / Q000276:immunology; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C554292:12-O-tetradecanoylphorbol-1,3-acetate; D023181:Antimicrobial Cationic Peptides; D018925:Chemokines; D016207:Cytokines; C088334:Distal-less homeobox proteins; D018398:Homeodomain Proteins; D007211:Indoles; D008301:Maleimides; D014157:Transcription Factors; D051571:Protein Kinase C-alpha; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium