title: Involvement of AP-1 in interleukin-1alpha-stimulated MMP-3 expression in human trabecular meshwork cells.
abstract: OBJECTIVE
  Stromelysin-1 (MMP-3) degrades extracellular matrix and increases aqueous outflow. In the trabecular meshwork (TM), interleukin (IL)-1alpha is a potent inducer of MMP-3 expression. In different cells, IL-1alpha activates different signaling pathways, such as nuclear factor (NF)-kappaB-mediated protein expression, the phospholipase A(2) (PLA(2))-activated arachidonate cascade, and activator protein (AP)-1-associated transcription. In the present study, pharmacological tools were used to delineate the signaling mechanism involved in the effect of IL-1alpha on MMP-3 production in human TM cells compared with other ocular cells.
  
  
  METHODS
  Human TM and three other ocular cells (ciliary muscle, corneoscleral fibroblast, and lamina cribrosa) were cultured in 24-well plates in the presence or absence of IL-1alpha, with or without specific inhibitors of selected signaling pathways. Secreted proMMP-3 was quantified by ELISA, and MMP-3 activity was assayed by casein zymography.
  
  
  RESULTS
  IL-1alpha (5 ng/mL) increased proMMP-3 levels in human TM cells to 10- to 38-fold of control (P < 0.001). The effect of IL-1alpha was blocked by Gö6976, a protein kinase C micro (PKC micro ) inhibitor; PD98059, a mitogen-activated protein kinase kinase (MEK) inhibitor; SB202190, a p38 inhibitor; and SR11302, an AP-1 inhibitor; but not by inhibitors of casein kinase II, NFkappaB, PLA(2), phospholipase D (PLD), cyclooxygenases, lipoxygenase, or sphingomyelinase. SR11302 did not inhibit the effect of IL-1alpha on MMP-3 production in the other ocular cells tested.
  
  
  CONCLUSIONS
  Based on the pharmacological effects of the inhibitors, the data indicate that activation of PKC micro, MEK, and p38 leading to the activation of AP-1 is critical to the IL-1alpha-stimulated upregulation of MMP-3 in human TM cells. Therefore, it is likely that compounds that activate the AP-1 pathway would upregulate the production of MMP-3 and improve aqueous outflow.
authors.affiliation: Alcon Research, Ltd., Fort Worth, Texas 76134, USA. iok-hou.pang@alconlabs.com
authors.forename: Debra L
authors.initials: DL
authors.lastname: Fleenor
authors.forename: Iok-Hou
authors.initials: IH
authors.lastname: Pang
authors.forename: Abbot F
authors.initials: AF
authors.lastname: Clark
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D002460:Cell Line; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007223:Infant; D007375:Interleukin-1 / Q000494:pharmacology*; D048728:MAP Kinase Kinase Kinase 1; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis*; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D014129:Trabecular Meshwork / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004791:Enzyme Inhibitors; D007375:Interleukin-1; D018808:Transcription Factor AP-1; C089212:protein kinase D; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human; D020778:Matrix Metalloproteinase 2