title: Angiotensin II signals mechanical stretch-induced cardiac matrix metalloproteinase expression via JAK-STAT pathway.
abstract: BACKGROUND
  Mechanical stress induces many pathophysiological effects in cardiomyocytes. The objective of this study was to test the hypothesis that angiotensin II is a potential mediator of stretch-induced activation of matrix metalloproteinases (MMP).
  
  
  METHODS
  Neonatal rat cardiomyocytes grown on a flexible membrane were cyclically stretched achieving up to 20% elongation at 60 cycles/min (using a vacuum). We explored the signaling pathways involved in cyclical stretch-induced expression of MMP-14 and MMP-2.
  
  
  RESULTS
  Cyclical mechanical stretch significantly increased mRNA expression and protein synthesis for MMP-14 and MMP-2 from the 6(th) to 24(th) h. The increase in MMP-14 and -2 proteins after stretch was completely blocked after the pretreatment with losartan (an angiotensin II AT1 receptor antagonist, 200 nM) and AG-490 (a Janus kinase 2 tyrosine kinase inhibitor, 100 nM) but not with PD 98059 (an inhibitor of p42/p44 mitogen-activated protein kinase, 50 microM) or wortmannin (a phosphatidylinositol 3-kinase, 30 nM). By zymography, MMP-2 activity was increased by cyclical stretch that was significantly attenuated by losartan and AG-490. The mechanical strain also increased the immunohistochemical labeling of MMP-14 and -2 that was attenuated by adding losartan. Cyclical stretch increased the expression of STAT-1 that was abolished by pretreating with losartan or AG-490 (50 microM and 100 microM).
  
  
  CONCLUSIONS
  These findings indicate that cyclical stretch induces MMP-14 and -2 expression in neonatal rat cardiomyocytes and that the induction is mediated by the angiotensin II-JAK-STAT1 pathway.
authors.affiliation: Department of Emergency Department, Shin-Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.
authors.forename: Tzong-Luen
authors.initials: TL
authors.lastname: Wang
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Yang
authors.forename: Hang
authors.initials: H
authors.lastname: Chang
authors.forename: Chi-Ren
authors.initials: CR
authors.lastname: Hung
mesh_terms: D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D053614:Janus Kinase 2; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis*; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D032383:Myocytes, Cardiac / Q000502:physiology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013314:Stress, Mechanical; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D050794:STAT1 Transcription Factor; C494081:Stat1 protein, rat; D015534:Trans-Activators; D000804:Angiotensin II; D011505:Protein-Tyrosine Kinases; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2