FIGURE 11.
Effects of oleate on Swe1 levels in isc1Δ cells treated with HU. A, Western blot to monitor the levels of Swe1 protein was performed in WT and isc1Δ cells treated with HU ± oleate at 4, 8, and 12 h. Anti-Myc antibody was used to detect Swe1-myc. B, using anti-Swe1 antibody, the levels of the Swe1 protein were evaluated in the absence of CDC55 and in the double mutant isc1Δ,cdc55Δ treated with HU with or without oleate. PSTAIR antibody was used as a loading control. C, schematic description of our findings proposing the following events: when cells are treated with HU, Isc1 activity increases leading to an increase of phytoceramides, specifically C18:1. These ceramides activate Cdc55/PP2A phosphatase, which in turn induces the decrease of Swe1 levels leading to dephosphorylation of Clb2-Cdc28 leading to a G2/M cell cycle progression. Experiments in A and B were independently repeated three times.