Introduction: AIntroduction: Activated Ras/MEK/MAPK signal transduction pathway has been implicated in vascular smooth musle cell (VSMC) proloferation induced by different hormons such as Norepinephrine and Angiotensin II (ANG II). It plays an important role in pathogenesis of different cardiovascular diseases. It has been shown that Angiotensin II directly activates phospholipase D (PLD) in VSMC.
Aim: to determine whether PLD activation is mediated by activated Ras/MEK/MAPK signal transduction pathway in Angiotensin II-induced VSMC proliferation.
Methods: PLD activity has been measured by PLD assay using rabbit polyclonal antibodies against PLD, MAPK activity by Western blotting analysis using antiphospho-MAPK antibody and VSMC proliferation by 3H-thymidine incorporation. All assays have been determined in VSMC treated by Angiotensin II in presence or absance of different Ras, MEK, MAPK and PLD inhibitors.
Results: Angiotensin II treatment significantly induced VSMC proliferation. PLD and Ras/MEK/MAPK activities have been highly elevated in Angiotensin treated cells. However, when cells have been treated by ANG II in presence of FPT III, a Ras inhibitor and PD-98059, a MAK-inhibitor, PLD activity was decreased.
Conclusion: Activated Ras/MEK/MAPK signal transduction pathway mediates PLD activation in Angiotensin II-induced VSMC proliferation.