title: The unique and cooperative roles of the Grainy head-like transcription factors in epidermal development reflect unexpected target gene specificity.
abstract: The Grainy head-like 3 (Grhl3) gene encodes a transcription factor that plays essential roles in epidermal morphogenesis during embryonic development, with deficient mice exhibiting failed skin barrier formation, defective wound repair, and loss of eyelid fusion. Despite sharing significant sequence homology, overlapping expression patterns, and an identical core consensus DNA binding site, the other members of the Grhl family (Grhl1 and -2) fail to compensate for the loss of Grhl3 in these processes. Here, we have employed diverse genetic models, coupled with biochemical studies, to define the inter-relationships of the Grhl factors in epidermal development. We show that Grhl1 and Grhl3 have evolved complete functional independence, as evidenced by a lack of genetic interactions in embryos carrying combinations of targeted alleles of these genes. In contrast, compound heterozygous Grhl2/Grhl3 embryos displayed failed wound repair, and loss of a single Grhl2 allele in Grhl3-null embryos results in fully penetrant eyes open at birth. Expression of Grhl2 from the Grhl3 locus in homozygous knock-in mice corrects the wound repair defect, but these embryos still display a complete failure of skin barrier formation. This functional dissociation is due to unexpected differences in target gene specificity, as both GRHL2 and GRHL3 bind to and regulate expression of the wound repair gene Rho GEF 19, but regulation of the barrier forming gene, Transglutaminase 1 (TGase1), is unique to GRHL3. Our findings define the mechanisms underpinning the unique and cooperative roles of the Grhl genes in epidermal development.
authors.affiliation: Bone Marrow Research Laboratories, Melbourne Health Research Directorate, c/o Royal Melbourne Hospital Post Office, Parkville, Victoria 3050, Australia.
authors.forename: Yeliz
authors.initials: Y
authors.lastname: Boglev
authors.forename: Tomasz
authors.initials: T
authors.lastname: Wilanowski
authors.forename: Jacinta
authors.initials: J
authors.lastname: Caddy
authors.forename: Vishwas
authors.initials: V
authors.lastname: Parekh
authors.forename: Alana
authors.initials: A
authors.lastname: Auden
authors.forename: Charbel
authors.initials: C
authors.lastname: Darido
authors.forename: Nikki R
authors.initials: NR
authors.lastname: Hislop
authors.forename: Michael
authors.initials: M
authors.lastname: Cangkrama
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Ting
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Jane
mesh_terms: D000818:Animals; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004817:Epidermis / Q000196:embryology* / Q000648:ultrastructure; D055879:Gene Knock-In Techniques; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D008855:Microscopy, Electron, Scanning; D009024:Morphogenesis / Q000502:physiology*; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D011503:Transglutaminases / Q000378:metabolism; D014945:Wound Healing / Q000502:physiology
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; C528337:Grhl1 protein, mouse; C499942:Grhl3 protein, mouse; D012097:Repressor Proteins; D014157:Transcription Factors; C552738:grainy head-like 2 protein, mouse; D011503:Transglutaminases; C105804:transglutaminase 1