Regulation of a Dynamic Interaction between Two Microtubule-binding Proteins,EB1 and TIP150, by the Mitotic p300/CBP-associated Factor (PCAF) Orchestrates Kinetochore Microtubule Plasticity and Chromosome Stability during Mitosis

The microtubule cytoskeleton network orchestrates cellular dynamics and chromosome stability in mitosis. Although tubulin acetylation is essential for cellular plasticity, it has remained elusive how kinetochore microtubule plus-end dynamics are regulated by p300/CBP-associated factor (PCAF) acetylation in mitosis. Here, we demonstrate that the plus-end tracking protein, TIP150, regulates dynamic kinetochore-microtubule attachments by promoting the stability of spindle microtubule plus-ends. Suppression of TIP150 by siRNA results in metaphase alignment delays and perturbations in chromosome biorientation. TIP150 is a tetramer that binds an end-binding protein (EB1) dimer through the C-terminal domains, and overexpression of the C-terminal TIP150 or disruption of the TIP150-EB1 interface by a membrane-permeable peptide perturbs chromosome segregation. Acetylation of EB1-PCAF regulates the TIP150 interaction, and persistent acetylation perturbs EB1-TIP150 interaction and accurate metaphase alignment, resulting in spindle checkpoint activation. Suppression of the mitotic checkpoint serine/threonine protein kinase, BubR1, overrides mitotic arrest induced by impaired EB1-TIP150 interaction, but cells exhibit whole chromosome aneuploidy. Thus, the results identify a mechanism by which the TIP150-EB1 interaction governs kinetochore microtubule plus-end plasticity and establish that the temporal control of the TIP150-EB1 interaction by PCAF acetylation ensures chromosome stability in mitosis.     

Aberrant spindle dynamics and cytokinesis in Dictyostelium discoideum cells that lack glycogen synthase kinase 3

Eukaryotic cell division requires the co-ordinated assembly and disassembly of the mitotic spindle, accurate chromosome segregation and temporal control of cytokinesis to generate two daughter cells. While the absolute details of these processes differ between organisms, there are evolutionarily conserved core components common to all eukaryotic cells, whose identification will reveal the key processes that control cell division. Glycogen synthase kinase 3 (GSK-3) is a major protein kinase found throughout the eukaryotes and regulates many processes, including cell differentiation, growth, motility and apoptosis. In animals, GSK-3 associates with mitotic spindles and its inhibition causes mis-regulation of chromosome segregation. Two suppressor screens in yeast point to a more general effect of GSK-3 on cell division, however the direct role of GSK-3 in control of mitosis has not been explored outside the animal kingdom. Here we report that the Dictyostelium discoideum GSK-3 orthologue, GskA, associates with the mitotic spindle during cell division, as seen for its mammalian counterparts. Dictyostelium possesses only a single GSK-3 gene that can be deleted to eliminate all GSK-3 activity. We found that gskA-null mutants failed to elongate their mitotic spindle and were unable to divide in shaking culture, but have no chromosome segregation defect. These results suggest further conservation for the role of GSK-3 in the regulation of spindle dynamics during mitosis, but also reveal differences in the mechanisms ensuring accurate chromosome segregation.     

WEE1 激酶及其抑制剂在抗肿瘤治疗中的应用进展

WEE1激酶是一种细胞周期调节蛋白,能调控细胞周期蛋白依赖性激酶1(cyclin-dependent kinase 1,CDK1)的磷酸化状态,从而调节CDK1与细胞周期蛋白B(cyclin B)复合物的活性从而实现对细胞周期的调控,且对DNA损伤检查点具有重要的调节作用。WEE1是G2/M期阻滞的关键基因,起着重要的监测作用,在一些癌症中过表达,抑制或下调WEE1激酶均能引发有丝分裂灾难,因此WEE1激酶抑制剂可能在抗癌治疗中有关键作用。在癌症的治疗过程中,WEE1抑制剂与DNA损伤剂、化学药物等联合使用会得到比单独使用更为有效,且在p53缺失的癌细胞中能发挥更好的效果。目前WEE1已成为许多癌症治疗的关键靶点之一,其抑制剂MK-1775已处于临床研究阶段,且能增强一些DNA损伤剂对p53缺失的癌细胞的杀伤能力。本文就WEE1激酶及其抑制剂在抗癌治疗中的应用作一综述。     

Spatio-temporal expression of Prospero is finely tuned to allow the correct development and function of the nervous system in Drosophila melanogaster

Adaptive animal behaviors depend upon the precise development of the nervous system that underlies them. In Drosophila melanogaster, the pan-neural prospero gene (pros), is involved in various aspects of neurogenesis including cell cycle control, axonal outgrowth, neuronal and glial cell differentiation. As these results have been generally obtained with null pros mutants inducing embryonic lethality, the role of pros during later development remains poorly known. Using several pros-Voila (prosV) alleles, that induce multiple developmental and behavioral anomalies in the larva and in adult, we explored the relationship between these phenotypes and the variation of pros expression in 5 different neural regions during pre-imaginal development. We found that the quantity of pros mRNA spliced variants and of Pros protein varied between these alleles in a tissue-specific and developmental way. Moreover, in prosV1 and prosV13 alleles, the respective decrease or increase of pros expression, affected (i) neuronal and glial cell composition, (ii) cell proliferation and death and (iii) axonal-dendritic outgrowth in a stage and cellular context dependant way. The various phenotypic consequences induced during development, related to more or less subtle differences in gene expression, indicate that Pros level needs a precise and specific adjustment in each neural organ to allow its proper function.     

全麻联合椎旁神经阻滞在胸腔镜下肺叶切除术中的麻醉效果及对术后认知功能和炎症反应的影响

摘要 目的：研究全身麻醉联合椎旁神经阻滞在胸腔镜下肺叶切除术患者的应用效果,探讨其对患者术后认知功能和炎 症反应的影响。方法：选取2017年-2021年在我院接受胸腔镜下肺叶切除术治疗的患者100例,根据其麻醉方式的不同分为对照组（50例）和研究组（50例）,对照组给予全身麻醉,研究组给予全身麻醉联合椎旁神经阻滞。比较两组患者手术时间、麻醉时间、术中出血量、舒芬太尼和瑞芬太尼用量、术后疼痛情况、简易智力状态检查量表（MMSE）评分和血清C-反应蛋白（CRP）、白介素-6（IL-6）水平。结果：两组患者手术时间、麻醉时间和术中出血量比较无显著差异（P>0.05）,而研究组患者舒芬太尼用量和瑞芬太尼用量均低于对照组（P<0.05）;研究组患者术后6、12、24和48小时疼痛评分均较对照组患者低（P<0.05）;两组患者术前MMSE评分无差异（P>0.05）,研究组患者术后6、12、24和48小时MMSE评分均较对照组高（P<0.05）;两组患者术前血清CRP和IL-6水平无显著差异,但研究组患者术后24小时血清CRP和IL-6水平均显著低于对照组（P<0.05）。结论：全身麻醉联合椎旁神经阻滞用于胸腔镜下肺叶切除术患者可有效减少手术中麻醉药物用量,术后镇痛效果更好,对患者认知功能损伤更低,并且术后炎症更低。     

超声引导下髂筋膜神经阻滞联合全麻对老年股骨近端骨折患者术后血清疼痛介质PGE2、SP和认知功能及睡眠质量的影响

摘要 目的：观察超声引导下髂筋膜神经阻滞联合全麻对老年股骨近端骨折患者术后血清疼痛介质前列腺素E₂（PGE₂）、P物质（SP）和认知功能及睡眠质量的影响。方法：选取2018年8月~2021年9月期间我院收治的择期行手术治疗的老年股骨近端骨折患者80例,根据随机数字表法分为对照组（40例,常规全麻方案）和观察组（40例,超声引导下髂筋膜神经阻滞联合全麻方案）,对比两组麻醉效果、血流动力学、疼痛情况、认知功能和睡眠质量,观察不同模式麻醉下的安全性。结果：观察组的苏醒及拔管时间均短于对照组,丙泊酚使用量少于对照组（P<0.05）。两组置入喉罩时（T1）~术毕时（T3）心率（HR）先升高后下降,平均动脉压（MAP）先下降后升高（P<0.05）;观察组T1~T3时点HR低于对照组,MAP高于对照组（P<0.05）。两组术后24 h血清PGE₂、SP水平和视觉疼痛模拟量表（VAS）评分均升高,但观察组低于对照组（P<0.05）。两组术后1 d、2 d、3 d 蒙特利尔认知评估量表（MoCA）评分较术前先下降后升高（P<0.05）;观察组术后2 d、3 d MoCA评分高于对照组（P<0.05）。两组术后1 d、2 d、3 d匹兹堡睡眠质量评估量表（PSQI）评分较术前先升高后下降（P<0.05）;观察组术后1 d、2 d、3 d PSQI评分低于对照组（P<0.05）。两组不良反应发生率对比无差异（P>0.05）。结论：老年股骨近端骨折患者术中选用超声引导下髂筋膜神经阻滞联合全麻,镇痛效果显著,可稳定机体血流动力学,减少对认知功能和睡眠质量的影响,且安全性良好。     

Regeneration of specific innervation in Xenopus pectoralis muscle

We investigated the motor unit organization and precision of reinnervation in the Xenopus pectoralis muscle following different manipulations, including crush or section of the posterior pectoralis nerve, foreign nerve innervation, and crush coupled with activity modulation or block. Most fibers have two neuromuscular junctions, and multielectrode recordings were used to identify the axonal origin of all inputs to both junctions on most or all fibers covering about 25% of the muscle surface. Following simple nerve crush, a highly organized innervation pattern was restored, indistinguishable from the normal pattern, including selective innervation of fibers of similar input resistance (R_in), compact motor unit organization, and high incidence of exclusive innervation of both end plates on each fiber by the same axon (distributed mononeuronal innervation, or a/a pattern). Initial reinnervation was equally precise when nerve conduction in the regenerating nerve was blocked by tetrodotoxin. More distant or repeated nerve crush or nerve section delayed and reduced the precision of reinnervation, but the majority of fibers still received input to both end plates by the same axon, often in combination with others. A foreign nerve, the pectoralis sternalis, which in its own muscle forms only single end plates, showed less precise reinnervation, but still had an incidence of a/a innervation far above chance. These data imply the expression and recognition of remarkably precise chemospecific cues even in mature animals, superimposed on which is a further refinement by synapse elimination, probably based on an activity-dependent process. © 1996 John Wiley & Sons, Inc.     

ED50 G Na Block Predictions for Phenyl Substituted and Unsubstituted n-Alkanols

To study the role the phenyl group plays in producing local anesthetic block, a sequence of n-alkanols and phenyl-substituted alkanols (Φ-alkanols) were characterized in their ability to block Na channels. The sequence of n-alkanols studied possess 3–5 carbons (propanol-pentanol). The action of phenol and 3-Φ-alkanols (benzyl alcohol, phenethyl alcohol, 3-phenyl-1-propanol) were also studied. Na currents (I _Na ) were recorded from single frog skeletal muscle fibers using the Vaseline-gap voltage clamp technique. I _Na s were recorded prior to, during, and following the removal of the solutes in Ringer's solution. All alkanols and phenol acted to block I _Na in a dose-dependent manner. Effective doses to produce half block (ED₅₀) of I _Na or Na conductance (G _Na ) were obtained from dose-response relations for all solutes used. The block of G _Na depended on voltage, and could be separated into voltage-dependent and -independent components. Each solute acted to shift G _Na -V relations in a depolarized direction and reduce the maximum G _Na and slope of the relation. All solutes acted to speed up I _Na kinetics and cause hyperpolarizing shifts in steady-state inactivation. The magnitude of the kinetic changes increased with dose. Size was an important variable in determining the magnitude of the changes in I _Na ; however, size alone was not sufficient to predict the changes in I _Na . ED₅₀s for G _Na and AP block could be predicted as a function of intrinsic molar volume, hydrogen bond acceptor basicity (β) and donor acidity (α), and polarity (P) of the solutes. The equivalency of ED₅₀ predictions for AP and G _Na block can be explained by the fact that AP block arises from channel block and solute-induced changes in I _Na kinetics. Φ-alkanols were more effective at blocking and inactivating Na channels than their unsubstituted counterparts. Phenyl-substituted alkanols are more likely to interact with the channel than their unsubstituted counterparts. Received: 11 August 2000/Revised: 21 December 2000     

Stereospecific synthesis of "para-hydroxymexiletine" and sodium channel blocking activity evaluation

Both enantiomers of "para-hydroxymexiletine" (PHM), one of the main metabolites of mexiletine, were synthesized and fully characterized. Properties of (R)- and (S)-PHM, in terms of blocking potency and stereoselectivity on frog skeletal muscle Na(+) channels, were evaluated. The presence of a hydroxy group on the aryloxy moiety in the 4-position, as in PHM, reduced potency with respect to mexiletine in reducing I(Na max). However, PHM showed clear use-dependent behavior similar to that of mexiletine and, in contrast with what is observed with the parent compound, maintained its stereoselectivity during the use-dependent block. Chirality 16:72-78, 2004.