Mitochondrial ROS versus ER ROS: Which Comes First in Myocardial Calcium Dysregulation?

[摘要] Cardiomyocyte excitation–contraction coupling is tightly regulated through coordinated calcium release and uptake that is facilitated by two proteins in the sarco/endoplasmic reticulum (SR/ER) membrane, the ryanodine receptor (Ryr), and the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), respectively. Dysregulated calcium handling is a hallmark in cardiac dysfunction (1–3). Our understanding of the molecular mechanisms that underlie these calcium handling anomalies and their precise role in the associated pathologies remains incomplete. A growing body of indirect evidence has implicated a role for redox signaling, and the mitochondria have been thought to be the primary source of reactive oxygen species (ROS) (4–10). Research in this area suggests that ROS generated from the mitochondria alters the redox milieu around the SR/ER–mitochondria interface causing excessive oxidation of the cysteine residues in Ryr and SERCA that results in an increase in calcium release and decrease in uptake, respectively, thus depleting the SR/ER Ca2+ stores and causing dysregulated downstream signaling (4–10). However, many questions remain unanswered, and the source of the ROS has not been directly validated.

[学科分类] 心脏病和心血管学

[关键词] heart failure;endoplasmic reticulum stress;mitochondrial ROS;calcium dysregulation;unfolded protein response