title: Functional impact of ZEB1 mutations associated with posterior polymorphous and Fuchs' endothelial corneal dystrophies.
abstract: OBJECTIVE
  To assess the impact of zinc finger E-box binding homeobox 1 (ZEB1) gene mutations associated with posterior polymorphous corneal dystrophy 3 (PPCD3) and Fuchs' endothelial corneal dystrophy (FECD).
  
  
  METHODS
  Thirteen of the 27 previously reported ZEB1 truncating mutations associated with PPCD3 and the six previously reported ZEB1 missense mutations associated with FECD were generated and transiently transfected into a corneal endothelial cell line. Protein abundance was determined by immunoblotting, while intracellular localization was determined by fluorescence confocal microscopy.
  
  
  RESULTS
  Three of the 13 ZEB1 truncated mutants, and none of the missense mutants, showed significant decrease in mutant ZEB1 protein levels. Predominant nuclear localization was observed for truncated ZEB1 mutant proteins with a predicted molecular weight of less than 92 kilodaltons. The two largest mutant proteins that lacked a putative nuclear localization signal (NLS), p.(Ser638Cysfs*5) and p.(Gln884Argfs*37), primarily localized to the cytoplasm, while the NLS-containing mutant proteins, p.(Glu997Alafs*7) and p.(Glu1039Glyfs*6), primarily localized to the nucleus. All the missense ZEB1 mutant proteins were exclusively present in the nucleus.
  
  
  CONCLUSIONS
  ZEB1 truncating mutations result in a significant decrease and/or impaired nuclear localization of the encoded protein, indicating that ZEB1 haploinsufficiency in PPCD3 may result from decreased protein production and/or impaired cellular localization. Conversely, as the reported ZEB1 missense mutations do not significantly impact protein abundance or nuclear localization, the effect of these mutations on ZEB1 function and their relationship to FECD, if any, remain to be elucidated.
authors.affiliation: The Jules Stein Eye Institute, David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Duk-Won D
authors.initials: DW
authors.lastname: Chung
authors.affiliation: The Jules Stein Eye Institute, David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Ricardo F
authors.initials: RF
authors.lastname: Frausto
authors.affiliation: The Jules Stein Eye Institute, David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Lydia B
authors.initials: LB
authors.lastname: Ann
authors.affiliation: The Jules Stein Eye Institute, David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Jang
authors.affiliation: The Jules Stein Eye Institute, David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California, United States.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Aldave
mesh_terms: D002460:Cell Line; D004247:DNA / Q000235:genetics*; D004252:DNA Mutational Analysis; D004728:Endothelium, Corneal / Q000378:metabolism* / Q000473:pathology; D005642:Fuchs' Endothelial Dystrophy / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D018613:Microscopy, Confocal; D009154:Mutation; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D000071799:Zinc Finger E-box-Binding Homeobox 1
chemical_list: D018398:Homeodomain Proteins; D014157:Transcription Factors; C486307:ZEB1 protein, human; D000071799:Zinc Finger E-box-Binding Homeobox 1; D004247:DNA
keywords: Fuchs' endothelial corneal dystrophy; ZEB1; corneal endothelium; posterior polymorphous corneal dystrophy