April 1, 1989Journal of Clinical Investigation157 citationsOpen Access
Molecular cloning and characterization of a Ca2+ + Mg2+-dependent adenosine triphosphatase from rat cardiac sarcoplasmic reticulum. Regulation of its expression by pressure overload and developmental stage.
Key Result
Pressure overload markedly decreased cardiac Ca2+-ATPase mRNA levels to 32% of sham levels at 1 month, suggesting regulation at the pretranslational level.
Key Points
- The aim is to understand how cardiac Ca2+-ATPase expression is regulated in the heart under different conditions.
- Isolated cDNA encoding Ca2+-ATPase from rat cardiac sarcoplasmic reticulum (N=2311 nucleotides).
- Performed Northern blot analyses to assess mRNA levels of Ca2+-ATPase under pressure overload and developmental stages.
- Correlated mRNA levels with corresponding protein levels.
- mRNA levels of Ca2+-ATPase decreased to 32% of control levels after one month of pressure overload.
- Fetal mRNA levels were low, sharply increasing around birth, indicating developmental regulation.
- Protein levels corresponded to the observed mRNA levels, suggesting regulation at the pretranslational level.
Structured PICO
P
Population
Male Wistar rats and embryos/neonates evaluated for cardiac Ca2+-ATPase expression during pressure overload-induced hypertrophy and developmental stages.
E
Exposure
Pressure overload
C
Comparator
Sham operation
O
Outcome
mRNA and protein levels of Ca2+-ATPasesurrogate
Cardiac Ca2+-ATPase expression in the sarcoplasmic reticulum is regulated at the pretranslational level by pressure overload and developmental stage.
Main Result
Absolute Event Rate: 32% vs 100%
p-value: p=<0.001
Limitations
- Whether changes in Ca2+-ATPase mRNA levels are due to changes in transcriptional rate or mRNA stability remains to be proven.
Abstract
To investigate the regulation of expression of cardiac Ca2+ + Mg2+-dependent ATPase (Ca2+-ATPase) in sarcoplasmic reticulum (SR), we isolated cDNA (pHA6) encoding a Ca2+-ATPase of rat cardiac SR. The clone consisted of 2,311 mRNA-derived nucleotides, which covered half the coding region and the entire 3'-untranslated regions. The nucleotides and deduced amino acid sequences of pHA6 showed striking homology, 89 and 98%, respectively, to those of rabbit Ca2+-ATPase of the slow-twitch form. Northern blot analyses revealed that the mRNA levels of Ca2+-ATPase were decreased by pressure overload and became 32% of sham in 1 mo. During the developmental stage the mRNA levels were very low in the fetal period and steeply increased around birth. These changes in mRNA levels were correlated with the corresponding protein levels. These results suggest that the expression of cardiac Ca2+-ATPase in SR is regulated by pressure overload and the developmental stage, at least in part, at the pretranslational level.