An essential role for stromal interaction molecule 1 in neointima formation following arterial injury

There is evidence to suggest that stromal interaction molecule 1 (STIM1) functions as a Ca2+ sensor on the endoplasmic reticulum, leading to transduction of signals to the plasma membrane and opening of store-operated Ca2+ channels (SOC). SOC have been detected in vascular smooth muscle cells (VSMCs) and are thought to have an essential role in the regulation of contraction and cell proliferation. We hypothesized that knockdown of STIM1 inhibits VSMC proliferation and suppresses neointimal hyperplasia. We examined the effect of the knockdown of STIM1 using a rat balloon injury model and cultured rat aortic VSMCs. Interestingly, knockdown of rat STIM1 by adenovirus delivery of small interfering RNA (siRNA) significantly suppressed neointimal hyperplasia in a rat carotid artery balloon injury model at 14 days after injury. The re-expression of human STIM1 to smooth muscle reversed the effect of STIM1 knockdown on neointimal formation. Rat aortic VSMCs were used for the in vitro assays. Knockdown of endogenous STIM1 significantly inhibited proliferation and migration of VSMCs. Moreover, STIM1 knockdown induced cell-cycle arrest in G0/G1 and resulted in a marked decrease in SOC. Replenishment with recombinant human STIM1 reversed the effect of siRNA knockdown. These results suggest STIM1 has a critical role in neointimal formation in a rat model of vascular injury. STIM1 may represent a novel therapeutic target in the prevention of restenosis after vascular interventions.