STIMulating blood pressure

Abstract

The protein STIM1 helps to maintain membrane coupling sites in smooth muscle cells that regulate arterial contractility and blood pressure.

Keywords: STIM1; Stromal Interaction Molecules; blood pressure; molecular biophysics; mouse; peripheral coupling sites; smooth muscle; store-operated calcium entry; structural biology.

Figure 1.. STIM1 performs distinct functions in contractile and proliferative arterial smooth muscle cells.

In contractile smooth muscle cells (left), local increases in intracellular calcium concentration occur at peripheral coupling sites, allowing signaling to take place between proteins located in the SR/ER membrane and the plasma membrane without interfering with the rest of the cell. This signaling mechanism regulates smooth muscle cells within the walls of arteries, which contract and relax to modulate how much blood can flow to organs, controlling systemic blood pressure. Krishnan et al. found that loss of STIM1 reduces peripheral coupling sites in contractile arterial smooth muscle cells. This affects local signaling mechanisms, leading to over-dilated vessels and a decrease in blood pressure. Injury or disease of the vasculature (right) can shift arterial smooth muscle cells into a non-contractile, proliferative and migratory state. In this state, STIM1 does not maintain peripheral coupling sites, and instead takes on its canonical role inducing store-operated calcium entry (SOCE), which stimulates cells to multiply and migrate, altering the structure of blood vessels.