Chromosome condensation is a hallmark of mitosis in eukaryotes and is a prerequisite for faithful segregation of genetic material to daughter cells. Here we show that condensin, which is essential for assembling condensed chromosomes, helps to preclude the detrimental effects of gene transcription on mitotic condensation. ChIP-seq profiling reveals that the fission yeast condensin preferentially binds to active protein-coding genes in a transcription-dependent manner during mitosis. Pharmacological and genetic attenuation of transcription largely rescue bulk chromosome segregation defects observed in condensin mutants. We also demonstrate that condensin is associated with and reduces unwound DNA segments generated by transcription, providing a direct link between an in vitro activity of condensin and its in vivo function. The human condensin isoform condensin I also binds to unwound DNA regions at the transcription start sites of active genes, implying that our findings uncover a fundamental feature of condensin complexes.

Sister chromatid cohesion is mediated by cohesin and is essential for accurate chromosome segregation. The cohesin subunits SMC1, SMC3, and Rad21 form a tripartite ring within which sister chromatids are thought to be entrapped. This event requires the acetylation of SMC3 and the association of sororin with cohesin by the acetyltransferases Esco1 and Esco2 in humans, but the functional mechanisms of these acetyltransferases remain elusive. Here, we showed that Esco1 requires Pds5, a cohesin regulatory subunit bound to Rad21, to form cohesion via SMC3 acetylation and the stabilization of the chromatin association of sororin, whereas Esco2 function was not affected by Pds5 depletion. Consistent with the functional link between Esco1 and Pds5, Pds5 interacted exclusively with Esco1, and this interaction was dependent on a unique and conserved Esco1 domain. Crucially, this interaction was essential for SMC3 acetylation and sister chromatid cohesion. Esco1 localized to cohesin localization sites on chromosomes throughout interphase in a manner that required the Esco1-Pds5 interaction, and it could acetylate SMC3 before and after DNA replication. These results indicate that Esco1 acetylates SMC3 via a mechanism different from that of Esco2. We propose that, by interacting with a unique domain of Esco1, Pds5 recruits Esco1 to chromatin-bound cohesin complexes to form cohesion. Furthermore, Esco1 acetylates SMC3 independently of DNA replication.

The effects of six lipophilic vitamins: tretinoin (ATRA), vitamin D(3) (VD(3)), VE, VK(1), VK(3), and VK(5) on cell proliferation and apoptosis in human A375 melanoma cells were investigated. VD(3), VK(3), and VK(5) were found to inhibit cell proliferation significantly at concentration ranges of 10-100 μmol/L (p<0.01), while the other vitamins did not show inhibitory effects at 100 μmol/L. VK(3) and VK(5) showed the strongest effects with IC(50) values of less than 10 μmol/L. Dacarbazine slightly inhibited the proliferation of A375 cells at a concentration range of 25-100 μmol/L, but the effects were not statistically significant. VK(3) and VK(5) increased annexin-V positive apoptotic cells, as well as activating caspase-3, in A375 cells. Our findings showed that VD(3), VK(3,) and VK(5) inhibited the growth of dacarbazine resistant human melanoma cells, while ATRA, VE, and VK(1) had little effect on the cell growth. The effects of VK(3) and VK(5) were observed at concentrations lower than 10 μmol/L, which are suggested to have resulted from apoptosis-induction in the melanoma cells.

At the onset of anaphase, a protease called separase breaks the link between sister chromatids by cleaving the cohesin subunit Scc1. This irreversible step in the cell cycle is promoted by degradation of the separase inhibitor, securin, and polo-like kinase (Plk) 1-dependent phosphorylation of the Scc1 subunit. Plk could recognize substrates through interaction between its phosphopeptide interaction domain, the polo-box domain, and a phosphorylated priming site in the substrate, which has been generated by a priming kinase beforehand. However, the physiological relevance of this targeting mechanism remains to be addressed for many of the Plk1 substrates. Here, we show that budding yeast Plk1, Cdc5, is pre-deposited onto cohesin engaged in cohesion on chromosome arms in G2/M phase cells. The Cdc5-cohesin association is mediated by direct interaction between the polo-box domain of Cdc5 and Scc1 phosphorylated at multiple sites in its middle region. Alanine substitutions of the possible priming phosphorylation sites (scc1-15A) impair Cdc5 association with chromosomal cohesin, but they make only a moderate impact on mitotic cell growth even in securin-deleted cells (pds1Δ), where Scc1 phosphorylation by Cdc5 is indispensable. The same scc1-15A pds1Δ double mutant, however, exhibits marked sensitivity to the DNA-damaging agent phleomycin, suggesting that the priming phosphorylation of Scc1 poses an additional layer of regulation that enables yeast cells to adapt to genotoxic environments.

The present analyses identified age > 65 years, BMI, ALT, eGFR <30 mL/min/1.73 m, PT-INR, and concomitant use of antithrombotic drugs as independent risk factors for warfarin-related bleeding. We should pay attention to the risk factors associated with warfarin-related bleeding when prescribing warfarin in patients with renal impairment.