Lila Kim

Analysis of a genome-wide set of gene deletions in the fission yeast Schizosaccharomyces pombe.

We report the construction and analysis of 4,836 heterozygous diploid deletion mutants covering 98.4% of the fission yeast genome providing a tool for studying eukaryotic biology. Comprehensive gene dispensability comparisons with budding yeast—the only other eukaryote for which a comprehensive knockout library exists—revealed that 83% of single-copy orthologs in the two yeasts had conserved dispensability. Gene dispensability differed for certain pathways between the two yeasts, including mitochondrial translation and cell cycle checkpoint control. We show that fission yeast has more essential genes than budding yeast and that essential genes are more likely than nonessential genes to be present in a single copy, to be broadly conserved and to contain introns. Growth fitness analyses determined sets of haploinsufficient and haploproficient genes for fission yeast, and comparisons with budding yeast identified specific ribosomal proteins and RNA polymerase subunits, which may act more generally to regulate eukaryotic cell growth.

Activation of PKCβII and PKCθ is essential for LDL-induced cell proliferation of human aortic smooth muscle cells via Gi-mediated Erk1/2 activation and Egr-1 upregulation

Native LDL may be a mitogenic stimulus of VSMC proliferation in lesions where endothelial disruption occurs. Recent studies have demonstrated that the mitogenic effects of LDL are accompanied by Erk1/2 activation via an unknown G-protein-coupled receptor (GPCR). In this article, we report that LDL translocated PKCbeta(II) and PKCtheta from cytosol to plasma membrane, and inhibition of PKCbeta(II) and PKCtheta decreased LDL effects via the deactivation of Erk1/2. Moreover, pertussis toxin, but not cholera toxin or heparin, inhibited LDL-induced translocation of PKCbeta(II) and PKCtheta, suggesting that Gi protein plays a role in LDL effects. Of LPA, S1P, and LDL, whose signaling is conveyed via Gi/o proteins, only LDL induced translocation of PKCbeta(II) and PKCtheta. Inhibition of PKCbeta(II) or PKCtheta, as well as of Erk1/2 and GPCR, decreases LDL-induced upregulation of Egr-1, which is critical for cell proliferation. This is the first report, to our knowledge, that the participation of PKCtheta in VSMC proliferation is unique.