title: The novel function of advanced glycation end products in regulation of MMP-9 production.
abstract: BACKGROUND
  Advanced glycation end products (AGEs), formed from proteins and peptides by nonenzymatic glycoxidation after contact with aldose sugars, have been implicated in the pathogenesis of age-related cardiac and vascular dysfunction. Our previous study demonstrated significantly elevated levels of AGE and the receptor for AGE (RAGE) in human abdominal aortic aneurysm (AAA) tissues. Inhibition of AGE signaling by targeted gene deletion of RAGE markedly reduced the development of aneurysm in a mouse model of AAA. We also showed that AGE may stimulate aneurysm formation by promoting metalloproteinase (MMP)-9 expression. In this study, we investigated the molecular mechanism underlying this novel function of AGE.
  
  
  METHODS
  The murine macrophage cell line RAW 264.7 was pretreated with AGE, TGF-β, and MAPK inhibitors. The protein was collected for Western blot analysis. Culture supernatants were collected to determine MMP-9 activity by gelatin zymography.
  
  
  RESULTS
  We found that AGE induced the production of MMP-9 in macrophages in a dose-dependent manner. This induction of MMP-9 was markedly diminished by pretreatment with TGF-β. To delineate the underlying molecular mechanism, we showed that AGE increased phosphorylation of p44/42 ERK, p38, JNK, and PI3K in macrophages. Moreover, AGE induced active p65 subunit of NF- κB. Inhibition of ERK (UO126) or p38 (SB203580), but not PI3K (LY294002 or wortmannin), blocked AGE-induced MMP-9 expression. In contrast, inhibition of JNK (SP-600125) significantly enhanced the stimulatory effect of AGE on MMP-9. Furthermore, TGF-β suppressed AGE-induced expression of the active p65 subunit of NF-κB.
  
  
  CONCLUSIONS
  Our data indicate that AGE induces MMP-9 through activation of ERK, p38 mitogen-activated protein and NF-κB, a pathway that is antagonized by TGF-β. This finding in conjunction with previously reported AGE functions in inflammation suggests that anti-AGE therapies could be effective in the prevention of human AAA development and progression.
authors.affiliation: Department of Surgery, Division of Vascular Surgery, University of Wisconsin School of Medicine, Madison, Wisconsin 53705, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Greg
authors.initials: G
authors.lastname: Banker
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Liu
authors.forename: Pasithorn A
authors.initials: PA
authors.lastname: Suwanabol
authors.forename: Justin
authors.initials: J
authors.lastname: Lengfeld
authors.forename: Dai
authors.initials: D
authors.lastname: Yamanouchi
authors.forename: K Craig
authors.initials: KC
authors.lastname: Kent
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
mesh_terms: D000818:Animals; D017544:Aortic Aneurysm, Abdominal / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D017737:Macrophages, Peritoneal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D017127:Glycation End Products, Advanced; D016328:NF-kappa B; D016212:Transforming Growth Factor beta; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse