INDUCTION OF ANTIOXIDANT GENES BY KLOTHO AND SULFORAPHANE IN HUMAN AORTIC SMOOTH MUSCLE CELLS: ROLE OF NRF2 AND SULFORAPHANE

Aim: Vascular smooth muscle cell (SMC) dysfunction due to oxidative stress contributes to age-related cardiovascular diseases. Klotho, a protein associated with anti-ageing, can extend lifespan when overexpressed while deficiencies result in rapid ageing. Sulforaphane (SFN), an isothiocyanate in vegetables, can induce antioxidant genes mediated by the Nrf2 transcription pathway. This study investigates whether Klotho and SFN can increase heme oxygenase-1 (HO-1) and peroxiredoxin-1 (Prx-1) expression in human aortic SMC. Methods: Cells were treated (0-24h) with SFN (0-5μM) or Klotho (0-1nM) and HO-1/Prx-1 expression determined by immunoblotting. Nrf2 knock-down was achieved by siRNA transfection. Glutathione (GSH) levels and generation of reactive oxygen species (ROS) in response to Angiotensin II (200nM, 4h) were measured using fluorescence and luminescence assays respectively. Results: SFN and Klotho significantly enhanced HO-1 and Prx-1 expression in a Nrf2-dependent manner, and increased GSH levels at 24h (p<0.05, n=3). Treatment with Klotho (1nM, 24h) diminished Angiotensin II induced ROS generation. Our data also show that SFN (5uM, 24h) can enhance the induction of Klotho and HO-1. Conclusions: Taken together, these findings demonstrate that both SFN and Klotho can enhance antioxidant defences which may protect against vascular SMC dysfunction in age-related cardiovascular diseases.