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Increased expression of biglycan mRNA in pressure-overloaded rat heart
Y Ayada1, S Kusachi, T Murakami
1Department of Internal Medicine I, Okayama University Medical School, Japan.
Abstract:
Biglycan mRNA expression in rat myocardium after abdominal aortic banding with renal ischemia was examined. The Northern blot analysis demonstrated that expression of biglycan mRNA in the pressure-overloaded hearts on days 2, 7, 14 and 28 was 2.88 +/- 0.89, 2.32 +/- 0.49, 2.17 +/- 0.57 and 1.81 +/- 0.46-fold higher, respectively, than that in the sham-operated hearts. In situ hybridization showed an increased density of biglycan mRNA signal-positive cells in the pressure-overloaded hearts. The cells with positive signals were spindle-shaped mesenchymal cells in the myocardial interstitium. A marked increase in biglycan mRNA signal expression was also observed in endothelial cells and smooth muscle cells of the thickened myocardial capillary wall. These results demonstrated an increase in biglycan mRNA in the pressure-overloaded heart in mesenchymal cells in the myocardial interstitium, and in endothelial and smooth muscle cells of the capillaries, indicating that biglycan contributes to the ventricular and vascular remodeling in response to pressure overload.
Insights
Biglycan mRNA expression significantly increased in rat hearts subjected to pressure overload. This suggests biglycan plays a key role in cardiac and vascular remodeling following pressure-induced heart conditions.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Extracellular Matrix Research
Background:
- Pressure overload is a major cause of cardiac remodeling and heart failure.
- The role of specific extracellular matrix proteins, like biglycan, in this process requires further elucidation.
Purpose of the Study:
- To investigate biglycan mRNA expression in the rat myocardium following abdominal aortic banding with renal ischemia.
- To determine the cellular localization of biglycan mRNA in pressure-overloaded hearts.
Main Methods:
- Northern blot analysis to quantify biglycan mRNA levels.
- In situ hybridization to identify the location of biglycan mRNA expression within cardiac tissue.
Main Results:
- Biglycan mRNA expression was significantly elevated (2- to 3-fold) in pressure-overloaded hearts compared to sham-operated controls at multiple time points (days 2, 7, 14, 28).
- Increased biglycan mRNA signals were observed in mesenchymal cells within the myocardial interstitium.
- Enhanced biglycan mRNA expression was also detected in endothelial and smooth muscle cells of thickened myocardial capillaries.
Conclusions:
- Biglycan mRNA is upregulated in the myocardium in response to pressure overload.
- Biglycan expression in interstitial mesenchymal cells and vascular cells suggests its involvement in both ventricular and vascular remodeling.
- These findings highlight biglycan as a potential contributor to the cardiac and vascular adaptations to sustained pressure overload.