Increased MMP-9 expression and activity by aortic smooth muscle cells after nitric oxide synthase inhibition is associated with increased nuclear factor-kappaB and activator protein-1 activity.
OBJECTIVE
To determine the mechanism underlying increased expression and activity of matrix metalloproteinase 9 (MMP-9) by rat aortic smooth muscle cells (RA-SMC) after inhibition of inducible nitric oxide synthase (iNOS).


RESULTS
Treatment of interleukin-1beta-stimulated RA-SMC with aminoguanidine led to an increase of 96% in MMP-9 activity (P = 0.003) by gelatin zymography, a 40% increase in pro-MMP-9 protein (P = 0.018) by Western blot, and a 155% increase in MMP-9 mRNA (P = 0.06) by reverse transcription polymerase chain reaction. Aminoguanidine also caused a 26% decrease in cytosolic IkappaB levels (P = 0.014) by Western blot, as well as a 97% increase in nuclear factor-kappaB binding and a 216% increase in activator protein-1 binding as measured by electrophoretic mobility shift assay. No significant changes were noted in MMP-2 or TIMP-1 expression, protein levels, or activity after aminoguanidine administration.


CONCLUSIONS
MMP-9 expression and activity is increased in cytokine stimulated RA-SMCs after iNOS inhibition, coincident with activation of the nuclear factor-kappaB and activator protein-1 pathways. We speculate that local derangements in iNOS may favor MMP-9-dependent vessel wall damage in vivo via an inflammatory cascade mechanism.
Knipp
Brian S
BS
Jobst Vascular Research Laboratories, Section of Vascular Surgery, Ann Arbor, Michigan 48109-0329, USA. riversu@umich.edu
Ailawadi
Gorav
G
Ford
John W
JW
Peterson
David A
DA
Eagleton
Matthew J
MJ
Roelofs
Karen J
KJ
Hannawa
Kevin K
KK
Deogracias
Michael P
MP
Ji
Baoan
B
Logsdon
Craig
C
Graziano
Kathleen D
KD
Simeone
Diane M
DM
Thompson
Robert W
RW
Henke
Peter K
PK
Stanley
James C
JC
Upchurch
Gilbert R
GR
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000201:enzymology*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D006146:Guanidines / Q000494:pharmacology; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000201:enzymology*; D016328:NF-kappa B / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D052247:Nitric Oxide Synthase Type II; D011498:Protein Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism*
D006146:Guanidines; D016328:NF-kappa B; D011498:Protein Precursors; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D018808:Transcription Factor AP-1; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D019278:Matrix Metalloproteinase 3; D020778:Matrix Metalloproteinase 2; C004479:pimagedine