Discussion
Findings highlight PAR2 and PAR2-driven PKA/MEK1/2 in control of VSM cell growth and provide evidence for continued investigation of PAR2 in VSM pathology.
Methods
Rat clonal low (PLo; P3-P6) and high passage (PHi; P10-P15) VSM cells were established as respective models of quiescent and proliferative cells, based on reduced PKG-1 and VASP. Western blotting determined expression of cytoskeletal/contractile proteins, PAR2, and select protein kinases. DNA synthesis and cell proliferation were measured 24-72 h following PAR2 agonism (SLIGRL; 100 nM-10 μ<sc>m</sc>) with/without PKA (PKI; 10 μ<sc>m</sc>), MEK1/2 (PD98059; 10 μ<sc>m</sc>), and PI3K (LY294002; 1 μ<sc>m</sc>) blockade.
Results
PKG-1, VASP, SM22α, calponin, cofilin, and PAR2 were reduced in PHi versus PLo cells. Following PAR2 agonism, DNA synthesis and cell proliferation increased in PLo cells but decreased in PHi cells. Western analyses showed reduced PKA, MEK1/2, and PI3K in PHi versus PLo cells, and kinase blockade revealed PAR2 controls VSM cell proliferation through PKA/MEK1/2.