Gαq G proteins modulate MMP-9 gelatinase during remodeling of the murine femoral artery

Abstract

Background Vessels heal after injury and G protein-coupled receptors are involved in the vascular smooth muscle cell (VSMC) proliferation required to form intimal hyperplasia. We have previously identified the role of Gαq in VSMC proliferation in vitro. This study now examines the role of Gαq in the developing intimal hyperplasia in a murine model and the impact of disruption of Gαq signaling on intimal hyperplasia development. Methods The murine femoral wire injury model was employed in which a micro wire is passed through a branch of the femoral artery and used to denude the common femoral artery. Specimens were perfusion-fixed and sections were stained with H&E and Movat’s stains such that morphometric analysis could be performed using an Image-Pro system. Additional specimens of femoral artery were also harvested and snap frozen for western blotting or zymography to allow for the study of G protein expression and both protease expression and activity. Contralateral vessels were used as controls. Additional vessels were immersed in pluronic gel containing the chemical Gαq G protein inhibitors GP-2A, siRNA to Gαq or advenovirus containing mutant inactive Gαq. Results Gαq expression increased in a time-dependent manner after femoral artery injury. Sham operated on vessels did not produce such a response. Inhibition of Gαq reduced cell proliferation without affecting cell migration. Interruption of Gαq signaling also inhibited the development of intimal hyperplasia. Inhibition of Gαq did not alter peak uPA activity and expression but did increase early PAI-1 activity and expression. Inhibition of Gαq reduced peak MMP-9 activity at day 3 but did not influence peak MMP-2 activity at day 7. Protein expression for MMP-9 was also decreased but that of MMP-2 was not affected. There were no changes in the expression or the activity of the respective inhibitors for MMP-9 and MMP-2, TIMP-1 and TIMP-2. Conclusions These data demonstrate that femoral wire injury in the mouse is associated with a time-dependent increase in Gαq expression. Inhibition of Gαq alters cell proliferation and is associated with decreased MMP-9 expression and activity.

Effect of metabolic syndrome on the response to arterial injury

“…Sham operated vessels did not produce such a response (18, 19). Cell apoptosis peaked within 3 days and cell proliferation peaked at 7 days after injury.…”

“…We had previously demonstrated that under normal circumstances, murine injured femoral arteries developed intimal hyperplasia, which is maximal at 28 days and does not change substantially between day 28 and day 56 (18, 19). Sham operated vessels did not produce such a response (18, 19).…”