Redox Signaling in Human Brain Vascular Smooth Muscle Cells

Background Stroke is a leading cause of death in the U.S. and worldwide. Ischemic stroke is the major type of stroke, in which blood vessels in the brain become blocked. Thickening of the vascular wall narrows the lumen of the brain vessel and increases the incidence of ischemic stroke. Smooth muscle cell (SMC) growth contributes to the thickening of the vascular wall. Therapeutic strategies to inhibit and/or reverse brain vascular SMC growth, therefore, should reduce the incidence of ischemic stroke. However, the mechanism of brain vascular SMC growth is not well understood. Redox processes through the generation of reactive oxygen species (ROS) regulate cell signaling in various biological processes. The present study examined redox signaling, in particular, iron‐dependent protein carbonylation signaling in brain vascular SMCs. Methods & Results Treatment of cultured human brain vascular SMCs with deferoxamine (an iron chelator) resulted in a dose‐dependent reduction of cell growth induced by serum or by platelet‐derived growth factor (PDGF) as monitored by CCK8 colorimetric cell viability assay. As our laboratory previously discovered that iron‐catalyzed protein carbonylation mediates cell signaling in other cell types, we tested the effects of PDGF on protein carbonylation in human brain vascular SMCs. Treatment with PDGF promoted transient carbonylation of various proteins with a peak at 10 min. U0126, an inhibitor of the MEK/ERK pathway suppressed PDGF‐induced growth of human brain vascular SMCs and deferoxamine reduced ERK phosphorylation and activation in response to PDGF, suggesting that redox signaling occurs upstream from the ERK activation. The immunohistochemistry detection of malondialdehyde in brain tissues from human patients who died of stroke indicated the production of ROS in the vascular smooth muscle layer. Conclusions We demonstrate that redox signaling mediates the growth of brain vascular SMCs, opening up the possibility for targeting redox processes to improve therapeutic strategies to reduce the incidence of ischemic stroke. Support or Funding Information Supported by NIH