title: The role of eIF5A in epidermal growth factor-induced proliferation of corneal epithelial cell association with PI3-k/Akt activation.
abstract: OBJECTIVE
  After excimer laser surgery, epidermal growth factor (EGF) plays an important role in injured corneal epithelial cell on myofibroblastic cell formation in corneal stroma. The purpose of the study is to investigate the precise mechanism of EGF on corneal wound healing, particularly on epithelial proliferation and migration.
  
  
  METHODS
  In this study we applied small interference RNA (siRNA) to knock down the expression of eukaryotic translation initiation factor 5A (eIF5A) in corneal epithelial cells. The relative mRNA and protein expression of matrix metallopeptidase 9 (MMP9) and proliferating cell nuclear antigen (PCNA) was determined via real-time PCR and western blot analysis. The proliferative potential of EGF was evaluated via a proliferation assay using the measurement of (3)H-thymidine incorporation ((3)H-TdR). HCEpiC apoptosis was subjected to flow cytometric analysis.
  
  
  RESULTS
  The results showed eIF5A expression was enhanced and there was a statistically significant increase in EGF treatment compared to the control group. Real-time PCR, western blot analysis, and the proliferation assay demonstrated significantly lower MMP9 and PCNA expression and proliferation cell counts in eIF5A siRNA-treated groups versus significantly higher levels in EGF plus eIF5A siRNA-treated groups. The data analysis showed that eIF5A, MMP9, and PCNA expression decreased as a result of the inhibitor LY294002. Apoptotic cells were increased in the EGF plus eIF5A siRNA, EGF plus LY294002, and EGF plus eIF5A siRNA plus LY294002 groups as compared with the EGF siRNA group.
  
  
  CONCLUSIONS
  These results indicate that EGF-induced upregulation of eIF5A stimulates corneal epithelial cell proliferation in vitro. EGF stimulation of corneal epithelial proliferation was through the phosphatidylinositol 3-kinase (PI3-k)/protein kinase B (Akt) signaling pathway.
authors.affiliation: Department of Ophthalmology, EENT Hospital, Fudan University, Shanghai, P.R. of China.
authors.forename: Lan
authors.initials: L
authors.lastname: Ding
authors.forename: Ling-Juan
authors.initials: LJ
authors.lastname: Gao
authors.forename: Ping-Qing
authors.initials: PQ
authors.lastname: Gu
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Guo
authors.forename: You-Qun
authors.initials: YQ
authors.lastname: Cai
authors.forename: Xing-Tao
authors.initials: XT
authors.lastname: Zhou
mesh_terms: D017209:Apoptosis; D049109:Cell Proliferation; D003315:Cornea / Q000166:cytology*; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology*; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000235:genetics* / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000502:physiology*; D015398:Signal Transduction; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D004815:Epidermal Growth Factor; D020780:Matrix Metalloproteinase 9; D010448:Peptide Initiation Factors; D019869:Phosphatidylinositol 3-Kinases; D018809:Proliferating Cell Nuclear Antigen; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A