Human Fetal Retinal Pigment Epithelium Induced Apoptosis of Jurkat T-cells Involves Caspase Activation and PARP Cleavage

Abstract

Abstract: : Purpose:To characterize the mechanisms involved in human fetal retinal pigment epithelium (HFRPE) induced apoptosis in human T-cells, we analyzed the caspase cascade in apoptotic Jurkat T-cells (Jkt) which were incubated with supernatant of HFRPE cells. Methods:Pure cultures of HFRPE cells were isolated. Jkt cells were incubated with the supernatant isolated from non-activated or IFN-g activated HFRPE cells for 12 to 36 hours. The activation of procaspase-3, procaspase-7, procaspase-8, and procaspase-10 as well as cleavage of the caspase-3 substrate poly (ADP-ribose) polymerase (PARP), was evaluated with Western-blott of whole cell lysates. Results:Incubation of Jkt cells with the supernatant isolated from IFN-g activated HFRPE cells induced cleavage of procaspase-3 and -7, but not of procaspase-8 and -10. Cleavage of PARP was also observed. Although incubation of Jkt cells with supernatant from non-activated HFRPE cells also showed similar results, the kinetics of procaspase and PARP cleavage showed significantly higher activity in IFN-g activated supernatant. Conclusion:Human fetal retinal pigment epithelium induced apoptosis in Jurkat cells involves caspase-3 and -7 activation as well as PARP cleavage, but not activation of the death receptor-associated initiator caspases: caspase-8 and -10. These data are in agreement with our previous published report indicating HFRPE cell-induced loss of mitochondrial membrane potential in Jkt cells and the absence of FasL and TRAIL involvement in HFRPE cell-mediated apoptosis.

Keywords: 435 immunomodulation/immunoregulation • 567 retinal pigment epithelium • 323 apoptosis/cell death