PGF 2α-associated vascular smooth muscle hypertrophy is ROS dependent and involves the activation of mTOR, p70 S6k, and PTEN

Abstract

Prostaglandin F 2α (PGF 2α) increases reactive oxygen species (ROS) and induces vascular smooth muscle cell (VSMC) hypertrophy by largely unknown mechanism(s). To investigate the signaling events governing PGF 2α-induced VSMC hypertrophy we examined the ability of the PGF 2α analog, fluprostenol to elicit phosphorylation of Akt, the mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70 S6k), glycogen synthase kinase-3β (GSK-3β), phosphatase and tensin homolog (PTEN), extracellular signal-regulated kinase 1/2 (ERK1/2) and Jun N-terminal kinase (JNK) in growth arrested A7r5 VSMC. Fluprostenol-induced hypertrophy was associated with increased ROS, mTOR translocation from the nucleus to the cytoplasm, along with Akt, mTOR, GSK-3β, PTEN and ERK1/2 but not JNK phosphorylation. Whereas inhibition of phosphatidylinositol 3-kinase (PI3K) by LY-294002 blocked fluprostenol-induced changes in total protein content, pre-treatment with rapamycin or with the MEK1/2 inhibitor U0126 did not. Taken together, these findings suggest that fluprostenol-induced changes in A7r5 hypertrophy involve mTOR translocation and occur through PI3K-dependent mechanisms.