title: An autocrine linkage between matrix metalloproteinase-14 and Tie-2 via ectodomain shedding modulates angiopoietin-1-dependent function in endothelial cells.
abstract: OBJECTIVE
  The angiopoietin (Ang)-Tie-2 system plays a critical role during fetal and adult angiogenesis. Herein, we explored the Tie-2 shedding-related molecular mechanisms and the pathophysiological significance.
  
  
  RESULTS
  By using a mouse hindlimb ischemia model, we observed dissociated expression between the full-length Tie-2 (fTie-2) protein and Tie-2 mRNA in thigh muscles 1 day after an ischemic operation, suggesting that fTie-2 expression was modified through the posttranscriptional regulation in vivo. A soluble form of Tie-2 produced in human umbilical vein endothelial cells was dramatically suppressed by treatment with siRNA-matrix metalloproteinase (MMP) 14 or tissue inhibitor of metalloproteinase 3, resulting in an increase in cellular fTie-2 and thereby enhancing Ang-1-dependent Akt phosphorylation and Akt-dependent endothelial functions, such as Ang-2 downregulation or an increase of endothelial viability. Phorbol-12-myristate-13 acetate (PMA) upregulates MMP-14 mRNA via protein kinase C-extracellular signal-regulated kinase pathways, and enhanced soluble Tie-2 production in an MMP-14-dependent manner, resulting in a reduction of cellular fTie-2. In addition, the PMA-induced soluble Tie-2 was mediated by the protein kinase C-extracellular signal-regulated kinase signaling pathways. Finally, downregulation of tissue inhibitor of metalloproteinase 3 and upregulation of MMP-14 mRNA were confirmed in ischemic thigh muscles 1 day after the operation.
  
  
  CONCLUSIONS
  An autocrine linkage between the endothelial protein kinase C-MMP-14 axis and Tie-2 shedding was shown to be a novel regulatory mechanism for the Ang-Tie-2 system and may play a role in modulating endothelial function during angiogenesis.
authors.affiliation: Division of Pathophysiological and Experimental Pathology, Department of Pathology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. onimaru@pathol1.med.kyushu-u.ac.jp
authors.forename: Mitsuho
authors.initials: M
authors.lastname: Onimaru
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Yonemitsu
authors.forename: Hanako
authors.initials: H
authors.lastname: Suzuki
authors.forename: Takaaki
authors.initials: T
authors.lastname: Fujii
authors.forename: Katsuo
authors.initials: K
authors.lastname: Sueishi
mesh_terms: D042683:Angiopoietin-1 / Q000378:metabolism*; D000818:Animals; D019898:Autocrine Communication / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D006614:Hindlimb; D006801:Humans; D007511:Ischemia / Q000201:enzymology* / Q000503:physiopathology; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000235:genetics / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000098:blood supply*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D011480:Protease Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D042787:Receptor, TIE-2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism; D014162:Transfection
chemical_list: C467630:ANGPT1 protein, human; D042683:Angiopoietin-1; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D020794:Receptor Protein-Tyrosine Kinases; D042787:Receptor, TIE-2; C079086:Tek protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; C507086:MMP14 protein, human; D053511:Matrix Metalloproteinase 14; D013755:Tetradecanoylphorbol Acetate