title: Fenretinide-induced neuronal differentiation of ARPE-19 human retinal pigment epithelial cells is associated with the differential expression of Hsp70, 14-3-3, pax-6, tubulin beta-III, NSE, and bag-1 proteins.
abstract: OBJECTIVE
  We reported earlier that fenretinide can induce neuronal differentiation of ARPE-19 human retinal pigment epithelial cells in culture. The purpose of this study was to investigate the potential involvement of key proteins involved in gene transcription, signal transduction, cell cycle check point, differentiation, neuronal cell survival, and stress response in the neuronal differentiation of ARPE-19 cells by fenretinide.
  
  
  METHODS
  Cells in culture were treated with 1.0 microM fenretinide. Cells were analyzed using antibodies against pax-6, neuronal specific enolase (NSE), tubulin beta-III, 14-3-3, bag-1, and Hsp-70 proteins using immunocytochemistry, western blot and ELISA methodologies.
  
  
  RESULTS
  We found that pax-6 and NSE were both expressed in the control ARPE-19 cells. Fenretinide induced neuronal differentiation of ARPE-19 cells led to a decrease in pax-6 protein and an increase in tubulin beta-III protein expression after 5 days fenretinide treatment. There was a translocation of 14-3-3 from the cytoplasm to the nucleus, and an increase in nuclear expression of bag-1 after treatment. We also found a time-dependent increase in Hsp70 protein expression in ARPE-19 cells treated with fenretinide. D-407, another human retinal pigment epithelial cell line, but not either Y-79 or PC-12 cells, was also able to be induced into neuronal morphologies by fenretinide.
  
  
  CONCLUSIONS
  The fenretinide-induced neuronal differentiation of ARPE-19 cells is associated with an increase in expression of the neuronal specific protein tubulin beta-III, and a decrease in expression of the progenitor cell marker pax-6. Neuronal differentiation of ARPE-19 cells is also associated with nuclear translocation of 14-3-3, a protein involved in signal transduction, cell cycle check point and cell growth, and an increase in expression of bag-1, a protein involved in neuronal cell survival and axon elongation. These results suggest that ARPE-19 cells could be a progenitor cell line that can be differentiated into neuronal cells when treated with factors such as fenretinide.
authors.affiliation: Biochemistry Section, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-0706, USA.
authors.forename: Shanyi
authors.initials: S
authors.lastname: Chen
authors.forename: Robert N
authors.initials: RN
authors.lastname: Fariss
authors.forename: R Krishnan
authors.initials: RK
authors.lastname: Kutty
authors.forename: Ralph
authors.initials: R
authors.lastname: Nelson
authors.forename: Barbara
authors.initials: B
authors.lastname: Wiggert
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000378:metabolism; D017313:Fenretinide / Q000494:pharmacology*; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D009474:Neurons / Q000166:cytology*; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; C091732:BCL2-associated athanogene 1 protein; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; C000605733:Pax6 protein, rat; D011506:Proteins; D012097:Repressor Proteins; C498585:TUBB3 protein, human; D014157:Transcription Factors; D014404:Tubulin; D017313:Fenretinide