title: MCS9.7 enhancer activity is highly, but not completely, associated with expression of Irf6 and p63.
abstract: BACKGROUND
  DNA variation in Interferon Regulatory Factor 6 (IRF6) contributes risk for orofacial clefting, including a common DNA variant rs642961. This DNA variant is located in a multi-species conserved sequence that is 9.7 kb upstream from the IRF6 transcriptional start site (MCS9.7). The MCS9.7 element was shown to possess enhancer activity that mimicked the expression of endogenous Irf6 at embryonic day 11.5 in transient transgenic embryos, and also contains a p63 binding site that transactivates IRF6 expression. To analyze whether the MCS9.7 enhancer is sufficient to drive IRF6 expression, we generated stable transgenic murine lines that carry a MCS9.7-lacZ transgene. We hypothesized that MCS9.7 was sufficient to recapitulate the endogenous expression of Irf6 at other time-points during embryonic development.
  
  
  RESULTS
  We observed that MCS9.7 activity recapitulated endogenous Irf6 expression in most tissues, but not in the medial edge epithelium (MEE) at E14.5, when Irf6 expression was high during secondary palatal fusion. Also, while MCS9.7 activity and Irf6 expression were associated with p63 expression, we observed MCS9.7 activity and Irf6 expression in periderm, although p63 was absent.
  
  
  CONCLUSIONS
  These data suggest that MCS9.7 enhancer activity is not sufficient to recapitulate IRF6 expression, and that p63 expression is not always necessary nor sufficient for transactivation of IRF6.
authors: Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48823, USA.
authors: Walid D
authors: WD
authors: Fakhouri
authors: Lindsey
authors: L
authors: Rhea
authors: Tianli
authors: T
authors: Du
authors: Eileen
authors: E
authors: Sweezer
authors: Harris
authors: H
authors: Morrison
authors: David
authors: D
authors: Fitzpatrick
authors: Baoli
authors: B
authors: Yang
authors: Martine
authors: M
authors: Dunnwald
authors: Brian C
authors: BC
authors: Schutte
mesh_terms: D000818:Animals; D002971:Cleft Lip / Q000235:genetics; D002972:Cleft Palate / Q000235:genetics; D004742:Enhancer Elements, Genetic; D004817:Epidermis / Q000196:embryology*; D004848:Epithelium / Q000196:embryology; D018507:Gene Expression Regulation, Developmental; D050835:Interferon Regulatory Factors / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D010159:Palate / Q000196:embryology* / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics*; D024363:Transcription Initiation Site; D015533:Transcriptional Activation; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: C528250:IRF6 protein, mouse; D050835:Interferon Regulatory Factors; D010750:Phosphoproteins; D015534:Trans-Activators; C486419:Trp63 protein, mouse; D001616:beta-Galactosidase