Redox regulation of cysteine‐674 of SERCA 2 is critical for growth factor‐and ischemia‐induced angiogenesis

The sarco/endoplasmic reticulum Ca 2+ ATPase (SERCA) is key to Ca 2+ homeostasis and is regulated by post‐translational modification of the cysteine (C) 674 thiol on which glutathione adducts stimulate Ca 2+ uptake activity and endothelial cell (EC) angiogenic responses in vitro . We found that mouse hind limb muscle ischemia induced by femoral artery ligation irreversibly oxidizes EC SERCA. To determine the role of thiol oxidation, we used a SERCA2 C674S heterozygote knock‐in (SKI) mouse lacking the key thiol. Following hind limb ischemia, SKI animals had impaired blood flow recovery. Cultured SKI microvascular EC showed impaired migration and decreased tube formation. Fura‐2 Ca 2+ signaling studies revealed lower Ca 2+ stores and decreased VEGF‐ and NO‐induced Ca 2+ influx. While VEGF decreased ionomycin‐releasable stores in WT EC, it failed to do so in SKI. Also, hypoxia‐induced expression of pro‐angiogenic genes (VEGF, VEGF receptor and eNOS) was decreased in SKI EC. Taken together, our data indicate that impairing normal redox regulation of the C674 thiol alters EC Ca 2+ homeostasis and angiogenic gene expression, suggesting mechanisms by which irreversible SERCA oxidation contributes to worsened angiogenesis during ischemia.