Metalloproteinase blockade by local overexpression of TIMP-1 increases elastin accumulation in rat carotid artery intima.
We have recently demonstrated that the blockade of matrix metalloproteinases by local overexpression of the intrinsic inhibitor tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) reduces intimal hyperplasia. We now report a major change in the elastin content of the intima of rat carotid arteries seeded with TIMP-1-overexpressing smooth muscle cells. To understand the mechanism responsible for elastin accumulation, synthesis and degradation of elastin in TIMP-1 and control cell-seeded rats were measured. There were no differences in elastin mRNA or elastin synthesis, as documented by 14[C]proline incorporation between TIMP-1 and control cell-seeded arteries. In contrast, there was an increase in cross-linked elastin in the TIMP-1 group. In addition, in TIMP-1 and control rats, an elastase activity of approximately 28 kD was detected by elastin zymography and was decreased in TIMP-1 cell-seeded vessels. The 28 kD elastolytic activity was inhibited by exogenously added TIMP-1 and EDTA but not by PMSF, suggesting that it was a metalloelastase. Therefore, we have demonstrated that a shift of the proteolytic balance toward protease inhibition by TIMP-1 overexpression does not change elastin synthesis but rather changes posttranslational processing, resulting in increased elastin accumulation.
Forough
R
R
Department of Surgery, University of Washington School of Medicine, Seattle 98195, USA.
Lea
H
H
Starcher
B
B
Allaire
E
E
Clowes
M
M
Hasenstab
D
D
Clowes
A W
AW
D000818:Animals; D002339:Carotid Arteries / Q000378:metabolism* / Q000473:pathology; D020212:Carotid Artery Injuries; D004549:Elastin / Q000096:biosynthesis* / Q000235:genetics; D008666:Metalloendopeptidases / Q000378:metabolism*; D010196:Pancreatic Elastase / Q000378:metabolism; D010215:Papio; D011480:Protease Inhibitors / Q000378:metabolism*; D012333:RNA, Messenger; D051381:Rats; D011916:Rats, Inbred F344; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000096:biosynthesis*
D011480:Protease Inhibitors; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D004549:Elastin; D010196:Pancreatic Elastase; D008666:Metalloendopeptidases