Accurate nuclear position is essential for each daughter cell to receive one DNA complement. In budding yeast, a surveillance mechanism known as the spindle position checkpoint ensures that exit from mitosis only occurs when the anaphase nucleus is positioned along the mother-bud axis. We identified the protein kinase Kin4 as a component of the spindle position checkpoint. KIN4 prevents exit from mitosis in cells with mispositioned nuclei by inhibiting the mitotic exit network (MEN), a GTPase signaling cascade that promotes exit from mitosis. Kin4 is active in cells with mispositioned nuclei and predominantly localizes to mother cells, where it is ideally situated to inhibit MEN signaling at spindle pole bodies (SPBs) when anaphase spindle elongation occurs within the mother cell.

mRNA alternative polyadenylation (APA) plays a critical role in post-transcriptional gene control and is highly regulated during development and disease. However, the regulatory mechanisms and functional consequences of APA remain poorly understood. Here, we show that an mRNA 3 0 processing factor, Fip1, is essential for embryonic stem cell (ESC) self-renewal and somatic cell reprogramming. Fip1 promotes stem cell maintenance, in part, by activating the ESC-specific APA profiles to ensure the optimal expression of a specific set of genes, including critical self-renewal factors. Fip1 expression and the Fip1-dependent APA program change during ESC differentiation and are restored to an ESC-like state during somatic reprogramming. Mechanistically, we provide evidence that the specificity of Fip1-mediated APA regulation depends on multiple factors, including Fip1-RNA interactions and the distance between APA sites. Together, our data highlight the role for post-transcriptional control in stem cell self-renewal, provide mechanistic insight on APA regulation in development, and establish an important function for APA in cell fate specification.

Recent work has identified several posttranslational modifications (PTMs) on chromatin-remodeling complexes. Compared with our understanding of histone PTMs, significantly less is known about the functions of PTMs on remodeling complexes, because identification of their specific roles often is hindered by the presence of redundant pathways. Remodels the Structure of Chromatin (RSC) is an essential, multifunctional ATP-dependent chromatin-remodeling enzyme of Saccharomyces cerevisiae that preferentially binds acetylated nucleosomes. RSC is itself acetylated by Gcn5 on lysine 25 (K25) of its Rsc4 subunit, adjacent to two tandem bromodomains. It has been shown that an intramolecular interaction between the acetylation mark and the proximal bromodomain inhibits binding of the second bromodomain to acetylated histone H3 tails. We report here that acetylation does not significantly alter the catalytic activity of RSC or its ability to recognize histone H3-acetylated nucleosomes preferentially in vitro. However, we find that Rsc4 acetylation is crucial for resistance to DNA damage in vivo. Epistatic miniarray profiling of the rsc4-K25R mutant reveals an interaction with mutants in the INO80 complex, a mediator of DNA damage and replication stress tolerance. In the absence of a core INO80 subunit, rsc4-K25R mutants display sensitivity to hydroxyurea and delayed S-phase progression under DNA damage. Thus, Rsc4 helps promote resistance to replication stress, and its single acetylation mark regulates this function. These studies offer an example of acetylation of a chromatin-remodeling enzyme controlling a biological output of the system rather than regulating its core enzymatic properties. R egulation of DNA accessibility within chromatin is enabled by the combined action of ATP-dependent chromatin-remodeling complexes and histone-modifying enzymes. Histone-modifying enzymes introduce covalent posttranslational modifications (PTMs) at specific locations. These PTMs either affect chromatin conformation directly or act as a signal for the recruitment of specific factors (1). ATP-dependent chromatin-remodeling complexes noncovalently alter chromatin conformation and composition using the energy of ATP (2). Intriguingly, these complexes also contain several different PTMs including acetylation and phosphorylation (2). However, compared with the functional effects of PTMs on histones, the functional effects of these PTMs are less well understood.Subunits of ATP-dependent chromatin-remodeling complexes often contain domains capable of recognizing specific PTMs. This phenomenon has been best studied in the context of histone tail acetylation, which is recognized by protein modules, called "bromodomains" (1, 2). In the SWI/SNF subfamily of remodelers, many subunits contain bromodomains (2), which have been shown to facilitate recruitment of these complexes to acetylated nucleosomes (3-7). Recent work has shown that bromodomains can bind acetylation marks in cis. Specifically, an acetylation mark on Rsc4, a subunit of RSC, the maj...

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Fundamento: A segurança e a eficácia da varfarina dependem da qualidade do controle da anticoagulação. Estudos observacionais associam controle deficiente com aumento de morbidade, mortalidade e custos com saúde. Objetivos: Desenvolver um perfil de pacientes com fibrilação atrial não valvar (FANV) tratados com varfarina em ambiente hospitalar privado brasileiro, avaliar a qualidade do controle da anticoagulação e sua associação com resultados clínicos e econômicos. Métodos: Este estudo retrospectivo, por meio de um grande conjunto de dados de seguros privados de saúde no Brasil, identificou pacientes com FANV tratados com varfarina entre 01 de maio de 2014 a 30 de abril de 2016, descreveu seu manejo da anticoagulação e quantificou os custos relacionados à doença. Foram recuperados dados demográficos, histórico clínico, medicação concomitante e tempo na faixa terapêutica (TTR) dos valores da razão normalizada internacional (RNI). Os pacientes foram agrupados em quartis de TTR, com um bom controle sendo definido como TTR ≥65% (método de Rosendaal). Sangramentos maiores e custos médicos diretos por todas as causas foram calculados e comparados entre subgrupos de controle bons e ruins. Valores de p < 0,05 foram considerados estatisticamente significantes. Resultados: A análise incluiu 1220 pacientes (mediana de seguimento: 1,5 anos; IIQ: 0,5–2,0). Em média, cada paciente recebeu 0,95 medidas mensais de RNI (RNI média: 2,60 ± 0,88, com 26,1% dos valores < 2 e 24,8% > 3), (mediana de TTR: 58%; IIQ: 47-68%), (TTR médio: 56,6% ± 18,9%). Apenas 31% dos pacientes estavam bem controlados (TTR médio: 78% ± 10%), com 1,6% apresentando grandes sangramentos na mediana do seguimento e custos médicos diretos por membro por ano (PMPY) de R$25.352 (± R$37.762). Pacientes mal controlados (69%) foram associados a 3,3 vezes mais sangramentos graves (5,3% vs. 1,6%; p <0,01) e custos 40% maiores (R$35.384 vs. R$25.352; p < 0,01). Conclusões: Mais de 60% dos pacientes estavam abaixo da meta desejada e os custos associados foram maiores. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)