Figure 5
From: S1P lyase regulates DNA damage responses through a novel sphingolipid feedback mechanism
ASMase is responsible for the effects of SPL on the DDR. (a) Control and SPLhi cells were left untreated or pretreated with Monensin (50 nM) for 3 h then cells were exposed to IR and caspase-3 activity was measured 24 h after radiation exposure. (b) SPLhi cells were either mock transfected or transfected with siRNA against human ASMase gene (SMPD1). After 48 h, cells were irradiated and harvested after 24 h. ASMase activity in knockdown and mock transfected cells was assayed. Caspase-3 activity was measured using DEVD-pNA as a substrate. Data represent mean±S.D. of three independent experiments. (*P<0.01; **P<0.001). (c and d) Control and SPLhi cells were pretreated with 20 μM desipramine or 250 nM monensin for 3 h. Cells were then exposed to IR and harvested 24 h after irradiation, and cell cycle distribution was examined by flow cytometry using PI staining. Histograms are representatives of three different experiments
