title: PI3-K/Akt/JNK/NF-κB is essential for MMP-9 expression and outgrowth in human limbal epithelial cells on intact amniotic membrane.
abstract: Matrix metalloproteinase-9 (MMP-9) plays an important role in the outgrowth of expanded human limbal epithelial cells on intact amniotic membranes (AM). The mechanisms of MMP-9 expression and cell outgrowth remain unknown. Here, we demonstrated that MMP-9 is preferentially expressed at the leading edge of limbal epithelial outgrowth. Treatment with the inhibitors of PI3-K (LY294002), Akt (SH-5), MEK1/2 (U0126), and JNK1/2 (SP600125) attenuated the outgrowth area, indicating that PI3-K/Akt, p42/p44 MAPK, and JNK1/2 are involved in the outgrowth of intact AM-expanded limbal epithelial cells. However, MMP-9 expression at both transcriptional and translational levels was attenuated by treatment with SP600125, LY294002, or SH-5, not by U0126 and SB202190, suggesting that JNK1/2 and PI3-K/Akt participate in MMP-9 expression. Moreover, NF-κB phosphorylation and nuclear translocation was especially noted at the leading edge, which was attenuated by treatment with SP600125 or LY294002. Helenalin, a selective NF-κB inhibitor, reduced both the limbal epithelial outgrowth and MMP-9 expression. Finally, the data reveal that PI3-K/Akt is an upstream component of the JNK1/2 pathway in MMP-9 expression. Thus, both MAPKs and PI3-K/Akt are required for limbal epithelial outgrowth on intact AM, only the PI3-K/Akt/JNK is essential for MMP-9 expression mediated through activation of transcriptional factor NF-κB in this model.
authors.affiliation: Department of Biomedical Engineering, Chung Yuan Christian University, Tao-Yuan, Taiwan.
authors.forename: Ching-Yi
authors.initials: CY
authors.lastname: Cheng
authors.forename: Hsi-Lung
authors.initials: HL
authors.lastname: Hsieh
authors.forename: Li-Der
authors.initials: LD
authors.lastname: Hsiao
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
mesh_terms: D000650:Amnion / Q000166:cytology*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016850:Limbus Corneae / Q000201:enzymology*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D048031:JNK Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9