title: CTCF-Mediated and Pax6-Associated Gene Expression in Corneal Epithelial Cell-Specific Differentiation.
abstract: BACKGROUND
  The purpose of the study is to elicit the epigenetic mechanism involving CCCTC binding factor (CTCF)-mediated chromatin remodeling that regulates PAX6 gene interaction with differentiation-associated genes to control corneal epithelial differentiation.
  
  
  METHODS
  Cell cycle progression and specific keratin expressions were measured to monitor changes of differentiation-induced primary human limbal stem/progenitor (HLS/P), human corneal epithelial (HCE) and human telomerase-immortalized corneal epithelial (HTCE) cells. PAX6-interactive and differentiation-associated genes in chromatin remodeling mediated by the epigenetic factor CTCF were detected by circular chromosome conformation capture (4C) and ChIP (Chromatin immunoprecipitation)-on-chip approaches, and verified by FISH (Fluorescent in situ hybridization). Furthermore, CTCF activities were altered by CTCF-shRNA to study the effect of CTCF on mediating interaction of Pax6 and differentiation-associated genes in corneal epithelial cell fate.
  
  
  RESULTS
  Our results demonstrated that differentiation-induced human corneal epithelial cells expressed typical corneal epithelial characteristics including morphological changes, increased keratin12 expression and G0/G1 accumulations. Expressions of CTCF and PAX6 were suppressed and elevated following the process of differentiation, respectively. During corneal epithelial cell differentiation, differentiation-induced RCN1 and ADAM17 were found interacting with PAX6 in the process of CTCF-mediated chromatin remodeling detected by 4C and verified by ChIP-on-chip and FISH. Diminished CTCF mRNA with CTCF-shRNA in HTCE cells weakened the interaction of PAX6 gene in controlling RCN1/ADAM17 and enhanced early onset of the genes in cell differentiation.
  
  
  CONCLUSIONS
  Our results explain how epigenetic factor CTCF-mediated chromatin remodeling regulates interactions between eye-specific PAX6 and those genes that are induced/associated with cell differentiation to modulate corneal epithelial cell-specific differentiation.
authors: Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Torrance, CA, 90502, United States of America.
authors: Shanli
authors: S
authors: Tsui
authors: Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Torrance, CA, 90502, United States of America.
authors: Jie
authors: J
authors: Wang
authors: Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Torrance, CA, 90502, United States of America.
authors: Ling
authors: L
authors: Wang
authors: Department of Environmental Medicine, New York University School of Medicine, Tuxedo, NY, 10987, United States of America.
authors: Wei
authors: W
authors: Dai
authors: Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Torrance, CA, 90502, United States of America.
authors: Luo
authors: L
authors: Lu
mesh_terms: D000076246:CCCTC-Binding Factor; D002453:Cell Cycle; D002454:Cell Differentiation; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D004843:Epistasis, Genetic; D019573:Epithelium, Corneal / Q000166:cytology* / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D007633:Keratins / Q000378:metabolism; D009928:Organ Specificity; D000071841:PAX6 Transcription Factor / Q000235:genetics* / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*
chemical_list: D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; D002843:Chromatin; D000071841:PAX6 Transcription Factor; D012097:Repressor Proteins; D007633:Keratins