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Nuclear Ca2+ regulates cardiomyocyte function.

Silvia Guatimosim¹, Maria Jimena Amaya, Mateus T Guerra

¹Department of Physiology and Biophysics, Federal University of Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte CEP: 31270-901, Brazil.

|January 19, 2008

Summary

This summary is machine-generated.

Nuclear calcium (Ca2+) signals in heart cells are crucial for cardiomyocyte function. Buffering nuclear Ca2+ impacts cell contraction, protein expression, and action potential duration, revealing a novel regulatory mechanism in the heart.

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Area of Science:

Cardiology
Cell Biology
Molecular Biology

Background:

Cytosolic calcium (Ca2+) signals regulate cardiomyocyte contraction.
The role of nuclear Ca2+ in cardiomyocyte function is not well understood.

Purpose of the Study:

To investigate the functional consequences of buffering nuclear Ca2+ in cardiomyocytes.
To explore the presence and function of nuclear Ca2+ signaling pathways in the heart.

Main Methods:

Utilized adenovirus constructs to deliver parvalbumin (a Ca2+ buffer) to either the nucleus or cytoplasm of neonatal cardiomyocytes.
Measured global Ca2+ transients, protein expression (RyR-II, calcineurin, NFAT), cell beating rate, and action potential duration.

Main Results:

Buffering nuclear Ca2+ altered global Ca2+ transients, RyR-II expression, and increased cell beating rate.
Nuclear Ca2+ buffering led to nuclear enlargement, increased calcineurin expression, NFAT translocation, and atrial natriuretic peptide redistribution.
Prolonged action potential duration was observed in adult ventricular myocytes.

Conclusions:

Nuclear Ca2+ levels regulate specific protein targets, modulating cardiomyocyte function.
Cardiomyocytes possess a nucleoplasmic reticulum with RyR and InsP3R, enabling active nuclear Ca2+ regulation.
Nuclear Ca2+ signaling represents a novel regulatory motif in cardiac function.