Effect of hypericin on the activity of protein kinase C in cultured human retinal pigment epithelial cells in vitro / 中华眼底病杂志

ABSTRACT

Objective To investigate the effect of hypericin on the activity of protein kinase C (PKC) in cultured human retinal pigment epithelium (RPE) cells in vitro. Methods RPE cells were cultured in standard medium with 10% serum concentrations containing 0.5 to 5.0 ?mol/L hypericin with or without preincubation of phorbol 12 myristate 13 acetate (PMA). The activities of cytosolic PKC (c PKC) and membranous PKC (m PKC) were assayed by PKC kit. Results The original activities of c PKC and m PKC of RPE cells were (35.34?4.10) pmol?min 1 ?mg 1 and (62.52?8.80) pmol?min 1 ?mg 1 . The activity of c PKC in RPE cells with PMA preincubation decreased rapidly in 5 minutes, with a subsequent slow decrease after 20 minutes and a decrease to 18% of the activity of c PKC in RPE cells without PMA preinubation after 60 minutes. While the activity of m PKC in RPE cells with PMA preincubation increased gradually after 5 minutes and reduced after reached the peak at 40 minutes, and then returned to baseline after 60 minutes, eventually decreased below 30% of the control group. When RPE cells were cultured with PMA for 48 hours, the activities of c PKC and m PKC were hardly detectable, while RPE cells were cultured with both PMA and hypericin, hypericin could counteract most of down regulation by PMA. Conclusion Hypericin may inhibit the translocation of PKC in RPE cells,change the activity of PKC, promote the apoptosis of RPE cells likely,and then prevent proliferative vitreoretinopathy.