Ki-67 is a PP1-interacting protein that organises the mitotic chromosome periphery

Copyright @ 2014 Booth et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.When the nucleolus disassembles during open mitosis, many nucleolar proteins and RNAs associate with chromosomes, establishing a perichromosomal compartment coating the chromosome periphery. At present nothing is known about the function of this poorly characterised compartment. In this study, we report that the nucleolar protein Ki-67 is required for the assembly of the perichromosomal compartment in human cells. Ki-67 is a cell-cycle regulated protein phosphatase 1-binding protein that is involved in phospho-regulation of the nucleolar protein B23/nucleophosmin. Following siRNA depletion of Ki-67, NIFK, B23, nucleolin, and four novel chromosome periphery proteins all fail to associate with the periphery of human chromosomes. Correlative light and electron microscopy (CLEM) images suggest a near-complete loss of the entire perichromosomal compartment. Mitotic chromosome condensation and intrinsic structure appear normal in the absence of the perichromosomal compartment but significant differences in nucleolar reassembly and nuclear organisation are observed in post-mitotic cells

Increased Anion Channel Activity Is an Unavoidable Event in Ozone-Induced Programmed Cell Death

Ozone is a major secondary air pollutant often reaching high concentrations in urban areas under strong daylight, high temperature and stagnant high-pressure systems. Ozone in the troposphere is a pollutant that is harmful to the plant. generation by salicylic and abscisic acids. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during programmed cell death.-induced programmed cell death. Because ion channels and more specifically anion channels assume a crucial position in cells, an understanding about the underlying role(s) for ion channels in the signalling pathway leading to programmed cell death is a subject that warrants future investigation

Nucleophosmin/B23 activates Aurora A at the centrosome through phosphorylation of serine 89.: Activation of Aurora-A by Nucleophosmin

International audienceAurora A (AurA) is a major mitotic protein kinase involved in centrosome maturation and spindle assembly. Nucleophosmin/B23 (NPM) is a pleiotropic nucleolar protein involved in a variety of cellular processes including centrosome maturation. In the present study, we report that NPM is a strong activator of AurA kinase activity. NPM and AurA coimmunoprecipitate and colocalize to centrosomes in G2 phase, where AurA becomes active. In contrast with previously characterized AurA activators, NPM does not trigger autophosphorylation of AurA on threonine 288. NPM induces phosphorylation of AurA on serine 89, and this phosphorylation is necessary for activation of AurA. These data were confirmed in vivo, as depletion of NPM by ribonucleic acid interference eliminated phosphorylation of CDC25B on S353 at the centrosome, indicating a local loss of AurA activity. Our data demonstrate that NPM is a strong activator of AurA kinase activity at the centrosome and support a novel mechanism of activation for AurA

Comparative Genomics for the Elucidation of Multidrug Resistance in Candida lusitaniae

Multidrug resistance (MDR) has emerged in hospitals due to the use of several agents administered in combination or sequentially to the same individual. We reported earlier MDR in Candida lusitaniae during therapy with amphotericin B (AmB), azoles, and candins. Here, we used comparative genomic approaches between the initial susceptible isolate and 4 other isolates with different MDR profiles. From a total of 18 nonsynonymous single nucleotide polymorphisms (NSS) in genome comparisons with the initial isolate, six could be associated with MDR. One of the single nucleotide polymorphisms (SNPs) occurred in a putative transcriptional activator (MRR1) resulting in a V668G substitution in isolates resistant to azoles and 5-fluorocytosine (5-FC). We demonstrated by genome editing that MRR1 acted by upregulation of MFS7 (a multidrug transporter) in the presence of the V668G substitution. MFS7 itself mediated not only azole resistance but also 5-FC resistance, which represents a novel resistance mechanism for this drug class. Three other distinct NSS occurred in FKS1 (a glucan synthase gene that is targeted by candins) in three candin-resistant isolates. Last, two other NSS in ERG3 and ERG4 (ergosterol biosynthesis) resulting in nonsense mutations were revealed in AmB-resistant isolates, one of which accumulated the two ERG NSS. AmB-resistant isolates lacked ergosterol and exhibited sterol profiles, consistent with ERG3 and ERG4 defects. In conclusion, this genome analysis combined with genetics and metabolomics helped decipher the resistance profiles identified in this clinical case. MDR isolates accumulated six different mutations conferring resistance to all antifungal agents used in medicine. This case study illustrates the capacity of C. lusitaniae to rapidly adapt under drug pressure within the host.IMPORTANCE Antifungal resistance is an inevitable phenomenon when fungal pathogens are exposed to antifungal drugs. These drugs can be grouped in four distinct classes (azoles, candins, polyenes, and pyrimidine analogs) and are used in different clinical settings. Failures in therapy implicate the sequential or combined use of these different drug classes, which can result in some cases in the development of multidrug resistance (MDR). MDR is particularly challenging in the clinic since it drastically reduces possible treatment alternatives. In this study, we report the rapid development of MDR in Candida lusitaniae in a patient, which became resistant to all known antifungal agents used until now in medicine. To understand how MDR developed in C. lusitaniae, whole-genome sequencing followed by comparative genome analysis was undertaken in sequential MDR isolates. This helped to detect all specific mutations linked to drug resistance and explained the different MDR patterns exhibited by the clinical isolates

The nucleoporin ALADIN regulates Aurora A localization to ensure robust mitotic spindle formation

The formation of the mitotic spindle is a complex process that requires massive cellular reorganization. Regulation by mitotic kinases controls this entire process. One of these mitotic controllers is Aurora A kinase, which is itself highly regulated. In this study, we show that the nuclear pore protein ALADIN is a novel spatial regulator of Aurora A. Without ALADIN, Aurora A spreads from centrosomes onto spindle microtubules, which affects the distribution of a subset of microtubule regulators and slows spindle assembly and chromosome alignment. ALADIN interacts with inactive Aurora A and is recruited to the spindle pole after Aurora A inhibition. Of interest, mutations in ALADIN cause triple A syndrome. We find that some of the mitotic phenotypes that we observe after ALADIN depletion also occur in cells from triple A syndrome patients, which raises the possibility that mitotic errors may underlie part of the etiology of this syndrome

Infections néonatales bactériennes précoces et immersion dans le bain pendant le travail dans un contexte de rupture des membranes à terme : Revue systématique de la littérature

Introduction / Objective: There are many advantages of immersion in warm water and many women choose to bath during labor. However, midwives have different opinions on its use when women have ruptured membranes especially because there is no recommendation on this practice, and there are concerns about the infectious risk for the newborn. Our objective is to determine if there is an increase of neonatal infections and their infectious morbidity during labor in this context. Methods: A systematic review of the literature has been carried out by searching the PubMed and Cochrane Library databases from July 2019 to April 2020, and using the Guide d’analyse de la littérature et gradation des recommandations written by the french authority HAS and the CONSORT and STROBE Reporting Guidelines. The study included articles written in English or French, discussing immersion in water during labor after rupture of the membranes at term and infectious neonatal morbidity (infections, Apgar score, admission in NICU, neonatal distress…). Results: A total of 7 studies has been included in this review. No significant increase of neonatal infections was observed within the immersion group. However, infectious morbidity was observed like a 5 min Apgar score significantly lower when the rupture is prolonged, a greater number of neonatal distress, or a greater number of hospitalized newborns for which their mother had premature rupture of the membranes at term within the immersion group. Nevertheless, these criteria were not specific of neonatal infections and can be criteria of asphyxia or other diseases. Conclusion: Our study does not allow us to give an opinion about immersion in water when the membranes are ruptured because of the bias and low levels of evidence of the studies included in this review. However, we do not recommend to bath during labor when the rupture of membranes is prolonged for more than 24 hours or when there is a premature rupture of the membranes.Introduction / Objectifs : L’immersion dans le bain a plusieurs avantages et nombreuses sont les femmes à l’utiliser durant le travail. Pourtant, les sages-femmes ont des avis divergents sur son utilisation une fois les membranes fœtales rompues et certaines craignent un risque infectieux pour le nouveau-né, notamment en l’absence de recommandation. Notre objectif est de déterminer s’il existe une augmentation des infections néonatales bactériennes et de la morbidité infectieuse pendant le travail dans ce contexte. Matériel et méthodes : Une revue systématique de la littérature a été réalisée sur les bases de données PubMed et Cochrane Library entre juillet 2019 et avril 2020 à l’aide du Guide d’analyse de la littérature et gradation des recommandations de la HAS et des lignes directrices CONSORT et STROBE. L’étude incluait des articles écrits en anglais ou en français, portant sur l’immersion dans le bain pendant le travail, avec rupture des membranes à terme et sur la morbidité infectieuse néonatale (infections, Apgar, taux d’hospitalisation, détresses respiratoires…). Résultats : Au total, 7 études ont été incluses. Aucune augmentation significative du taux d’infections néonatales bactériennes précoces pour le groupe avec immersion n’a été observée mais quelques retentissements ont été observés : score d’Apgar significativement plus bas en cas rupture prolongée, taux plus élevé de détresses respiratoires, taux d’hospitalisation plus élevé de nouveau-nés dont les mères avaient une rupture prématurée des membranes à terme dans le groupe immersion. Ces variables sont cependant non spécifiques des infections néonatales et peuvent être des signes d’hypoxie ou autres pathologies.Conclusion : Notre étude ne nous permet pas de nous positionner en faveur ou non de recommandation au vu des biais et du faible niveau de preuve des études. Néanmoins, nous ne pouvons pas recommander l’immersion dans le bain en cas de rupture des membranes prolongée supérieure à 24 heure ou de rupture prématurée des membranes à terme

Implications des harpines HrpNea et HrpWea, protéines de pathogénie de la bactérie Erwinia amylovora dans les étapes précoces d'interaction avec la cellule végétale

Les harpines sont des effecteurs protéiques sécrétés par le système de sécrétion de type III de certaines bactéries phytopathogènes. L'objectif des travaux présentés dans cette thèse fut d'étudier l'implication des harpines HrpNea et HrpWea dans l'interaction entre Erwinia amylovora et la cellule végétale. Dans un premier temps, nous avons travaillé avec des cellules en suspension d'Arabidopsis thaliana, plante non-hôte d'E. amylovora (situation incompatible). Sur ce modèle, l'inhibition des canaux anioniques est un événement précoce déterminant conduisant à la mort cellulaire en réponse à HrpNea. Nous nous sommes ensuite intéressés aux effets de HrpWea, l'autre harpine d'E. amylovora. Nos résultats montrent que HrpWea est une harpine dont les effets sur la mort cellulaire sont doubles. A 200 nM, HrpWea induit la mort tandis qu'à 0,2 nM, HrpWea est capable d'inhiber la mort cellulaire induite par la harpine HrpNea. La modulation des canaux anioniques apparaît aussi comme un événement déterminant de l'effet " protecteur " de HrpWea. Plus largement, ces résultats suggèrent que HrpWea peut être considérée comme un inhibiteur des réactions de défense de la cellule végétale. Enfin, nous avons étudié les effets de HrpNea chez un modèle cellulaire hôte (situation compatible), les cellules en suspension de pommier. Nous avons montré que les réponses induites par HrpNea en contexte hôte et en contexte non-hôte sont différentes, ce qui explique vraisemblablement le fait qu'HrpNea n'induit pas la mort chez ses plantes hôtes.Considérées dans leur ensemble, ces données ont permis d'améliorer la compréhension de l'implication des harpines d'E. amylovora dans la pathogénie et la réponse hypersensible induites par cette bactérie. D'une façon plus générale, ils ont aussi permis d'apporter de nouvelles informations quant au rôle des canaux ioniques dans les phénomènes de mort cellulaire programmée.Harpins are protean effectors secreted by type III secretion system of phytopathogenic bacteria. The aim of the present work was to investigate the involvement of HrpNea and HrpWea harpins from Erwinia amylovora during the interaction between this bacteria and the plant cell. We first worked with suspension cells from the non-host plant Arabidopsis thaliana (incompatible situation). On this model, we showed that anion channel inhibition is a determinant event leading to cell death triggered by HrpNea. We then studied the effects of HrpWea. Our results showed that HrpWea has different effects depending on its concentration. At high concentration , HrpWea induced cell death, whereas at low concentration , HrpWea was able to inhibit HrpNea induced cell death. Anion channel modulation also appeared to be a determinant event of cell death inhibition. More widely, these results suggested that HrpWea could be a plant cell defense mechanism inhibitor. Finally, we studied the effects of HrpNea on the host apple cells (compatible situation). We showed differential responses between host and non-host plant cells, likely explaining that HrpNea did not trigger cell death in host plants.Taken together, these data allowed us to improve our knowledge concerning involvement of HrpNea and HrpWea in E. amylovora hypersensitive response and pathogenicity. Moreover, these results bring new data concerning the role of ion channels during cell death.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Aurora Kinases

International audienc