SET Domain Protein Regulates S. pombe Cytokinesis Figure 7. The expression levels of cytokinesis related genes are not differentially regulated. (A) Cells of the indicated genotypes were grown to mid-log phase at 30uC in YES, and then treated with DMSO (A) or 0.5 mM LatA (B) for 3 hours. Total RNA was extracted and used in expression profiling using Affymetrix Yeast 2.0. Genechips. Graphs shows scatter plot analysis comparing the expression of cytokinesis related genes in wild-type and set3D strains. Green lines represent the threshold for a 1.5 fold change in transcript levels. The color of the squares indicates the level of expression of that gene in DMSO (A) or LatA (B) treated wild-type cells. doi:10.1371/journal.pone.0031224.g007 identifying three components of a histone de-acetylase complex (Hif2p, Set3p, and Snt1p) whose function is required to ensure the successful completion of cytokinesis upon perturbation of the cell division machinery (Figures 1 and 2). Moreover, through the creation of set3D lsk1D and set3D clp1D double mutants, we demonstrate that the complex functions through a novel branch of control, independently of both Lsk1p and Clp1p (Figure 3). This is consistent with genetic data indicating that, unlike the lsk1 gene deletion [13], set3D mutations are incapable of suppressing the lethal cytokinesis phenotype associated with SIN hyperactivation (data not shown). Lastly, through phenotypic analysis, co-immunoprecipita- tion data, and the analysis of intracellular localization, we provide support for a model in which Hif2p, Set3p, and Snt1p act together in a physical complex (Figures 2 and 4). PLoS ONE | www.plosone.org 9 February 2012 | Volume 7 | Issue 2 | e31224