X-ROS Signaling: Rapid Mechano-Chemo Transduction in Heart

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Science  09 Sep 2011:
Vol. 333, Issue 6048, pp. 1440-1445
DOI: 10.1126/science.1202768

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We report that in heart cells, physiologic stretch rapidly activates reduced-form nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) to produce reactive oxygen species (ROS) in a process dependent on microtubules (X-ROS signaling). ROS production occurs in the sarcolemmal and t-tubule membranes where NOX2 is located and sensitizes nearby ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR). This triggers a burst of Ca2+ sparks, the elementary Ca2+ release events in heart. Although this stretch-dependent “tuning” of RyRs increases Ca2+ signaling sensitivity in healthy cardiomyocytes, in disease it enables Ca2+ sparks to trigger arrhythmogenic Ca2+ waves. In the mouse model of Duchenne muscular dystrophy, hyperactive X-ROS signaling contributes to cardiomyopathy through aberrant Ca2+ release from the SR. X-ROS signaling thus provides a mechanistic explanation for the mechanotransduction of Ca2+ release in the heart and offers fresh therapeutic possibilities.

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