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Evolution of matrix metalloprotease and tissue inhibitor expression during heart failure progression in the infarcted
1Department of Cardiovascular Therapeutics, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, 2800 Plymouth Road, Ann Arbor, MI 48105, USA. tom.peterson@wl.com
Objective:
Characterize the timecourse of matrix metalloproteinase (MMP-1, -2, -3, -7, -9, -11, -12, -13, and -14) and endogenous tissue inhibitors of MMPs (TIMP-1, -2, -3, and -4) upregulation during left ventricular (LV) remodeling following myocardial infarction (MI) in rats.
Methods:
The descending left coronary artery of male rats (Rattus norvegicus) was ligated to produce a MI. LV function and dilation were assessed from 1 day to 16 weeks post-MI. Protein and mRNA extraction was done on LV samples containing scar and myocardium together. Gelatinase activity was measured by zymography. Westerns were run on the MMPs known to cleave fibrillar collagen in the rat (MMP-8, -13, and -14) as well as TIMP-1, -2, and -4.
Results:
Average infarct size was 38.6+/-1.1%, and produced LV dysfunction and progressive LV dilation. Thoracic ascites, a marker of congestive heart failure (HF), was not present until 12 weeks post-MI. Upregulation of MMP-2, -8, -9, -13, and -14 and TIMP-1 and TIMP-2 was detected at different timepoints during HF progression. Increased MMP protein levels occurred sometimes without a corresponding elevation in mRNA levels, and increased TIMP mRNA levels without increased protein levels. MMP-13 active form was elevated during the first 2 weeks post-MI while TIMP-1 and TIMP-2 protein levels were not significantly elevated until 2 weeks post-MI. MMP-8 and MMP-14 protein levels increased later during heart failure progression.
Conclusion:
MMP/TIMP upregulation evolves over time following infarction in the rat LV. Some MMPs were significantly elevated during the first week post-MI (MMP-13, -2, and -9) and another was not until 16 weeks post-MI (MMP-14). The dissociation between LV MMP/TIMP mRNA and protein levels shows that post-translation processing occurs in the rat heart.
Insights
Matrix metalloproteinase (MMP) and tissue inhibitor of MMP (TIMP) upregulation evolves over time following myocardial infarction (MI) in rats. Dissociation between MMP/TIMP mRNA and protein levels indicates post-translational processing in the rat heart.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Proteomics
Background:
- Left ventricular (LV) remodeling is a critical process following myocardial infarction (MI).
- Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) play significant roles in cardiac remodeling.
- Understanding the temporal expression of MMPs and TIMPs is crucial for therapeutic development.
Purpose of the Study:
- To characterize the time-dependent upregulation of specific MMPs (MMP-1, -2, -3, -7, -9, -11, -12, -13, -14) and TIMPs (TIMP-1, -2, -3, -4) in rat LV post-MI.
- To correlate MMP/TIMP expression patterns with functional and structural changes in the LV.
- To investigate potential post-transcriptional regulation of MMPs and TIMPs.
Main Methods:
- Myocardial infarction (MI) was induced in male rats via coronary artery ligation.
- LV function and dimensions were assessed serially from 1 day to 16 weeks post-MI.
- MMP and TIMP protein and mRNA levels were quantified using zymography and Western blotting.
Main Results:
- MI induced progressive LV dysfunction and dilation, with heart failure markers appearing at 12 weeks.
- Upregulation of MMP-2, -8, -9, -13, -14 and TIMP-1, -2 was observed at various stages of heart failure progression.
- Dissociation between mRNA and protein levels for MMPs and TIMPs suggests post-translational regulation.
Conclusions:
- MMP and TIMP expression profiles change dynamically during LV remodeling after MI in rats.
- Specific MMPs (MMP-13, -2, -9) were elevated early post-MI, while others (MMP-14) showed later increases.
- The observed discrepancies in mRNA and protein levels highlight the importance of post-translational modifications in regulating MMP/TIMP activity in the infarcted rat heart.