Kelli H. Nielson، نويسنده , , Cari A. Olsen، نويسنده , , Darin V. Allred، نويسنده , , Kim L. O’Neill، نويسنده , , Gregory F. Burton، نويسنده , , John D. Bell، نويسنده ,

1601575

Susceptibility of S49 lymphoma cell membranes to hydrolysis by secretory phospholipase A2 during early phase of apoptosis

12165

During cell death, plasma membranes of cells become vulnerable to attack by extracellular secretory phospholipase A2. The purpose of this study was to identify the timing of this phenomenon relative to other events that occur during the process of cell death. Death was induced in S49 murine lymphoma cells by treatment with dexamethasone, dibutyryl cAMP, ionomycin, thapsigargin, or heat shock (1 h at 43°C). The appearance of membrane susceptibility to secretory phospholipase A2 was compared to the following apoptotic events: loss of mitochondrial membrane potential, phosphatidylserine exposure in the outer leaflet of the cell membrane, early DNA damage assessed by the comet assay, and changes in cell size and internal complexity assessed by flow cytometry. Each inducer of death was distinct in the time course of events produced. Although dead cells were susceptible to the action of phospholipase A2, live cells (impermeable to propidium iodide) also became vulnerable to the enzyme during characteristic time courses after exposure to each inducer. In fact, susceptibility to sPLA2 was observed in each case prior to or concurrent with the earliest of the markers of apoptosis. These results demonstrate that the onset of susceptibility to sPLA2 is an early event in apoptosis suggesting that changes in membrane structure may be relevant to initial aspects of the apoptotic process.

163

Phospholipid hydrolysis , cell death , Comet assay , Phosphatidylserine exposure

Studia Iranica

174

174