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Growth factor for cardiac hypertrophy
1Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan.
Insights
Researchers isolated five cardiac growth proteins from hypertensive rat hearts. These proteins, particularly a 27 kD form, stimulate cardiac myocyte growth and DNA synthesis, crucial for regulating heart size.
Area of Science:
- Cardiology
- Molecular Biology
- Biochemistry
Background:
- Cardiac size is regulated by growth factors and inhibitors (chalones).
- Understanding cardiac growth factors is key to managing cardiac hypertrophy.
Purpose of the Study:
- To identify and purify cardiac growth factors from hypertrophied hearts.
- To investigate the role of these factors in cardiac myocyte proliferation.
Main Methods:
- Utilized hypertrophied rat hearts from renovascular hypertension models.
- Purified proteins using isoelectric focusing chromatography and HPLC.
- Assessed growth effects on cultured chicken embryonic cardiac myocytes.
- Analyzed cell cycle progression via DNA flow cytometry.
Main Results:
- Identified five proteins (isoelectric point 8.3) that significantly increased cardiac myocyte growth.
- Confirmed a 27 kD molecular weight is essential for growth-promoting activity.
- Observed increased BrdU incorporation in S and G2 phases, indicating stimulated DNA synthesis.
Conclusions:
- Hypertension-induced cardiac overload increases specific cardiac growth proteins.
- These purified proteins, especially the 27 kD form, directly stimulate cardiac myocyte DNA synthesis and growth.
- Findings provide insights into molecular mechanisms regulating cardiac size.
Abstract:
Cardiac size can be regulated by the balance in activity between cardiac growth factors and inhibiting factors, chalones. This study was undertaken to verify the role of the cardiac growth factor and its purification from hypertrophied hearts. For this propose the hypertrophied hearts of renovascular hypertensive rats were used. The purification was made by using an isoelectric focusing chromatography and the HPLC method. We examined the cardiac growth effect of the isolated fractions with cultured chicken embryonic cardiac myocytes. Simultaneously, the influence of these fractions on the cardiac cell cycle was examined by DNA analysis with the flow cytometric method. If the hearts were overloaded due to hypertension, the growth of the cardiac size could be induced by increased the level of five proteins with different molecular weight and with an isoelectric point of 8.3. The significant growth activities were observed at these five proteins compared to the absence of the fractions. For the appearance of these growth effect, it is necessary that the structure of the protein is there fundamentally as a form with a molecular weight of 27 k dalton. After addition of these isolated fractions, BrdU content is S and G2 phases by flow cytometry was increased. This change indicates that the cardiac myocytes are stimulated in form DNA synthesis.