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Gelatinase B(MMP-9) an apoptotic factor in diabetic transgenic mice
T M Camp1, S C Tyagi, R M Senior
1Department of Physiology and Biophysics, University of Louisville, 500 South Preston Street, Louisville, KY 40292, USA.
Aims/Hypothesis:
Although matrix metalloproteinase-9 (MMP-9) is specifically induced and apoptosis of endothelial cells is evidenced in diabetes mellitus, the mechanism of endocardial endothelial dysfunction in diabetes mellitus is not clear. The increase in MMP-9 activity is associated with endocardial endothelial apoptosis and dysfunction in diabetes mellitus.
Methods:
Diabetes was created by injecting 65 mg/kg alloxan in tail vein of MMP-9 knockout (-/-) and wild-type (WT, C57BL/J6) mice. At 8 weeks mice were grouped: (i) WT+saline; (ii) WT+alloxan; (iii) MMP+saline; (iv) MMP+alloxan. The MMP-9 genotype was determined by observing single PCR product of different mobility than the PCR product from wild-type in blood from tail vein.
Results:
MMP-9 activity, measured by zymography, increased in plasma and in the left ventricle of alloxan-induced diabetic wild-type mice. The concentrations of cardiac inhibitor of metalloproteinase, that blocks MMP-9 activity, were decreased in diabetic MMP-9 knockouts as well as in wild-type mice. Diabetes induced apoptosis, detected by TUNEL assays, in wild-type but not in MMP-9 knockouts. Endocardial endothelial function was severely impaired in diabetic wild-type mice compared with normoglycaemic animals, while non-diabetic MMP-9 knockout mice showed partial endocardial endothelial dysfunction which was not further exacerbated by the developments of diabetes.
Conclusion/Interpretation:
The results suggest an association between increased MMP-9 activity and endocardial endothelial apoptosis in diabetic mice, while genetic ablation of MMP-9 correlated with amelioration of endocardial endothelial dysfunction and apoptosis.
Insights
Increased matrix metalloproteinase-9 (MMP-9) activity contributes to heart endothelial cell apoptosis and dysfunction in diabetes. Genetic removal of MMP-9 protected against these diabetes-induced complications.
Area of Science:
- Cardiovascular Biology
- Diabetes Research
- Molecular Medicine
Background:
- Diabetes mellitus is associated with endothelial cell apoptosis and dysfunction.
- Matrix metalloproteinase-9 (MMP-9) is implicated in these processes, but its precise role in endocardial endothelial dysfunction remains unclear.
Purpose of the Study:
- To investigate the role of MMP-9 in diabetes-induced endocardial endothelial dysfunction and apoptosis.
- To determine if genetic ablation of MMP-9 can ameliorate these diabetic complications.
Main Methods:
- Diabetes was induced in wild-type (WT) and MMP-9 knockout mice using alloxan.
- Mice were grouped into WT+saline, WT+alloxan, MMP-9 knockout+saline, and MMP-9 knockout+alloxan.
- MMP-9 activity, cardiac inhibitor of metalloproteinase levels, apoptosis (TUNEL assay), and endocardial endothelial function were assessed.
Main Results:
- Alloxan-induced diabetes increased MMP-9 activity in WT mice plasma and left ventricle.
- Diabetes led to apoptosis in WT mice but not in MMP-9 knockout mice.
- Endocardial endothelial function was impaired in diabetic WT mice, while MMP-9 knockout mice showed partial dysfunction not exacerbated by diabetes.
Conclusions:
- Increased MMP-9 activity is associated with endocardial endothelial apoptosis and dysfunction in diabetic mice.
- Genetic deletion of MMP-9 ameliorates diabetes-induced endocardial endothelial dysfunction and apoptosis.
