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Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...
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Parallel Measurement of Circadian Clock Gene Expression and Hormone Secretion in Human Primary Cell Cultures
06:53

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Published on: November 11, 2016

Clock genes display rhythmic expression in human hearts.

Valentin Leibetseder1, Susanne Humpeler, Martin Svoboda

  • 1Center of Physiology and Pharmacology, University Vienna, Austria. valentin.leibetseder@meduniwien.ac.at

Chronobiology International
|May 16, 2009
PubMed
Summary
This summary is machine-generated.

Human heart cells express key circadian clock genes (PER1, PER2, BMAL1), with distinct daily rhythms that differ from rodents. These myocardial clock gene patterns may link to heart condition timing.

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Area of Science:

  • Cardiovascular Biology
  • Chronobiology
  • Molecular Cardiology

Background:

  • Circadian clock genes regulate physiological processes in mammals.
  • Previous studies identified clock genes in rodent hearts, linking their disruption to myocardial dysfunction.
  • Limited data existed on clock gene expression and function in human hearts.

Purpose of the Study:

  • To investigate the expression and circadian rhythmicity of core clock genes (PER1, PER2, BMAL1, CRY1) in human heart tissue.
  • To compare clock gene expression patterns between patients with coronary heart disease, cardiomyopathy, and healthy individuals.
  • To determine if human myocardial clock gene rhythms differ from those observed in rodents.

Main Methods:

  • Real-time PCR was used to quantify mRNA levels of PER1, PER2, BMAL1, and CRY1.
  • Circadian expression patterns were analyzed using sliding means and Cosinor functions.
  • Statistical analyses (ANOVAs) compared rhythmic patterns across patient groups and healthy donors.

Main Results:

  • All four clock genes (PER1, PER2, BMAL1, CRY1) were expressed in human heart tissue.
  • PER1, PER2, and BMAL1 exhibited significant circadian rhythms, with distinct acrophases (peak times) in the morning and evening.
  • CRY1 did not show a detectable circadian rhythm. Rhythmic patterns were consistent across all patient groups.
  • Human myocardial clock gene staging was found to be in antiphase compared to rodents.

Conclusions:

  • The human heart possesses robust circadian clock gene oscillations, particularly for PER1, PER2, and BMAL1.
  • These myocardial circadian rhythms are more pronounced than in other human tissues.
  • The timing of PER and BMAL1 rhythm peaks and troughs aligns with periods of increased myocardial events, suggesting a potential role in cardiovascular health.