Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
1.
Cell ; 167(5): 1201-1214.e15, 2016 11 17.
Artículo en Inglés | MEDLINE | ID: mdl-27863241

RESUMEN

Chromatin dynamics play an essential role in regulating DNA transaction processes, but it is unclear whether transcription-associated chromatin modifications control the mRNA ribonucleoparticles (mRNPs) pipeline from synthesis to nuclear exit. Here, we identify the yeast ISW1 chromatin remodeling complex as an unanticipated mRNP nuclear export surveillance factor that retains export-incompetent transcripts near their transcription site. This tethering activity of ISW1 requires chromatin binding and is independent of nucleosome sliding activity or changes in RNA polymerase II processivity. Combination of in vivo UV-crosslinking and genome-wide RNA immunoprecipitation assays show that Isw1 and its cofactors interact directly with premature mRNPs. Our results highlight that the concerted action of Isw1 and the nuclear exosome ensures accurate surveillance mechanism that proofreads the efficiency of mRNA biogenesis.


Asunto(s)
Adenosina Trifosfatasas/metabolismo , Proteínas de Unión al ADN/metabolismo , Ribonucleoproteínas/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Ensamble y Desensamble de Cromatina , Complejo Multienzimático de Ribonucleasas del Exosoma/metabolismo , Exosomas/metabolismo , Complejos Multiproteicos/metabolismo , ARN Polimerasa II/metabolismo
2.
Cell ; 142(2): 256-69, 2010 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-20619447

RESUMEN

The endoplasmic reticulum (ER) plays an essential role in the production of lipids and secretory proteins. Because the ER cannot be generated de novo, it must be faithfully transmitted or divided at each cell division. Little is known of how cells monitor the functionality of the ER during the cell cycle or how this regulates inheritance. We report here that ER stress in S. cerevisiae activates the MAP kinase Slt2 in a new ER stress surveillance (ERSU) pathway, independent of the unfolded protein response. Upon ER stress, ERSU alters the septin complex to delay ER inheritance and cytokinesis. In the absence of Slt2 kinase, the stressed ER is transmitted to the daughter cell, causing the death of both mother and daughter cells. Furthermore, Slt2 is activated via the cell surface receptor Wsc1 by a previously undescribed mechanism. We conclude that the ERSU pathway ensures inheritance of a functional ER.


Asunto(s)
Retículo Endoplásmico/metabolismo , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/metabolismo , Pared Celular/metabolismo , Proteínas del Citoesqueleto/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Fosforilación , Proteínas de Saccharomyces cerevisiae/metabolismo , Transducción de Señal , Estrés Fisiológico
3.
Nat Immunol ; 10(5): 504-13, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19363483

RESUMEN

Foxo transcription factors regulate cell cycle progression, cell survival and DNA-repair pathways. Here we demonstrate that deficiency in Foxo3 resulted in greater expansion of T cell populations after viral infection. This exaggerated expansion was not T cell intrinsic. Instead, it was caused by the enhanced capacity of Foxo3-deficient dendritic cells to sustain T cell viability by producing more interleukin 6. Stimulation of dendritic cells mediated by the coinhibitory molecule CTLA-4 induced nuclear localization of Foxo3, which in turn inhibited the production of interleukin 6 and tumor necrosis factor. Thus, Foxo3 acts to constrain the production of key inflammatory cytokines by dendritic cells and to control T cell survival.


Asunto(s)
Células Dendríticas/inmunología , Factores de Transcripción Forkhead/inmunología , Activación de Linfocitos/inmunología , Linfocitos T/inmunología , Animales , Presentación de Antígeno/inmunología , Antígenos CD/inmunología , Antígenos CD/metabolismo , Infecciones por Arenaviridae/inmunología , Western Blotting , Antígeno CTLA-4 , Células Dendríticas/metabolismo , Citometría de Flujo , Proteína Forkhead Box O3 , Factores de Transcripción Forkhead/metabolismo , Interleucina-6/inmunología , Interleucina-6/metabolismo , Virus de la Coriomeningitis Linfocítica/inmunología , Ratones , Ratones Congénicos , Ratones Transgénicos , Transporte de Proteínas/inmunología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Linfocitos T/metabolismo , Factor de Necrosis Tumoral alfa/inmunología , Factor de Necrosis Tumoral alfa/metabolismo
4.
Mol Cell ; 45(1): 132-9, 2012 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-22244335

RESUMEN

Histone H2B ubiquitylation is a transcription-dependent modification that not only regulates nucleosome dynamics but also controls the trimethylation of histone H3 on lysine 4 by promoting ubiquitylation of Swd2, a component of both the histone methyltransferase COMPASS complex and the cleavage and polyadenylation factor(CPF). We show that preventing either H2B ubiquitylation or H2B-dependent modification of Swd2 results in nuclear accumulation of poly(A) RNA due to a defect in the integrity and stability of APT, a subcomplex of the CPF. Ubiquitin-regulated APT complex dynamics is required for the correct recruitment of the mRNA export receptor Mex67 to nuclear mRNPs. While H2B ubiquitylation controls the recruitment of the different Mex67 adaptors to mRNPs, the effect of Swd2 ubiquitylation is restricted to Yra1 and Nab2, which, in turn, controls poly(A) tail length. Modification of H2B thus participates in the crosstalk between cotranscriptional events and assembly of mRNPs linking nuclear processing and mRNA export.


Asunto(s)
Histonas/metabolismo , Ribonucleoproteínas/metabolismo , Ubiquitinación , Transporte Activo de Núcleo Celular , Núcleo Celular/metabolismo , N-Metiltransferasa de Histona-Lisina/metabolismo , Proteínas Nucleares/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismo , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/metabolismo
5.
Biochim Biophys Acta ; 1819(6): 521-30, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22240387

RESUMEN

The production of mature and export competent mRNP (mRNA ribonucleoprotein) complexes depends on a series of highly coordinated processing reactions. RNA polymerase II (RNAPII) plays a central role in this process by mediating the sequential recruitment of mRNA maturation and export factors to transcribing genes, thereby establishing a strong functional link between transcription and export through nuclear pore complexes (NPC). Growing evidence indicates that post-translational modifications participate in the dynamic association of processing and export factors with mRNAs ensuring that the transitions and rearrangements undergone by the mRNP occur at the right time and place. This review mainly focuses on the role of ubiquitin conjugation in controlling mRNP assembly and quality control from transcription down to export through the NPC. It emphasizes the central role of ubiquitylation in organizing the chronology of events along this highly dynamic pathway. This article is part of a Special Issue entitled: Nuclear Transport and RNA Processing.


Asunto(s)
Poro Nuclear , ARN Mensajero , Ribonucleoproteínas , Ubiquitina , Núcleo Celular/genética , Núcleo Celular/metabolismo , Humanos , Poro Nuclear/genética , Poro Nuclear/metabolismo , Procesamiento Proteico-Postraduccional , ARN Polimerasa II/genética , ARN Polimerasa II/metabolismo , Transporte de ARN/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo , Transcripción Genética , Ubiquitina/genética , Ubiquitina/metabolismo , Ubiquitinación/genética
6.
J Cell Biol ; 177(6): 1017-27, 2007 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-17562790

RESUMEN

The unfolded protein response (UPR) pathway helps cells cope with endoplasmic reticulum (ER) stress by activating genes that increase the ER's functional capabilities. We have identified a novel role for the UPR pathway in facilitating budding yeast cytokinesis. Although other cell cycle events are unaffected by conditions that disrupt ER function, cytokinesis is sensitive to these conditions. Moreover, efficient cytokinesis requires the UPR pathway even during unstressed growth conditions. UPR-deficient cells are defective in cytokinesis, and cytokinesis mutants activate the UPR. The UPR likely achieves its role in cytokinesis by sensing small changes in ER load and making according changes in ER capacity. We propose that cytokinesis is one of many cellular events that require a subtle increase in ER function and that the UPR pathway has a previously uncharacterized housekeeping role in maintaining ER plasticity during normal cell growth.


Asunto(s)
Citocinesis , Retículo Endoplásmico/metabolismo , Ciclo Celular , Retículo Endoplásmico/genética , Chaperonas Moleculares , Pliegue de Proteína , Saccharomycetales
7.
Nat Commun ; 13(1): 6331, 2022 10 25.
Artículo en Inglés | MEDLINE | ID: mdl-36284099

RESUMEN

Cellular homeostasis is maintained by surveillance mechanisms that intervene at virtually every step of gene expression. In the nucleus, the yeast chromatin remodeler Isw1 holds back maturing mRNA ribonucleoparticles to prevent their untimely export, but whether this activity operates beyond quality control of mRNA biogenesis to regulate gene expression is unknown. Here, we identify the mRNA encoding the central effector of the unfolded protein response (UPR) HAC1, as an Isw1 RNA target. The direct binding of Isw1 to the 3' untranslated region of HAC1 mRNA restricts its nuclear export and is required for accurate UPR abatement. Accordingly, ISW1 inactivation sensitizes cells to endoplasmic reticulum (ER) stress while its overexpression reduces UPR induction. Our results reveal an unsuspected mechanism, in which binding of ER-stress induced Isw1 to HAC1 mRNA limits its nuclear export, providing a feedback loop that fine-tunes UPR attenuation to guarantee homeostatic adaptation to ER stress.


Asunto(s)
Proteínas de Saccharomyces cerevisiae , Regiones no Traducidas 3' , Adenosina Trifosfatasas/metabolismo , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Cromatina/metabolismo , Proteínas de Unión al ADN/metabolismo , Retículo Endoplásmico/genética , Retículo Endoplásmico/metabolismo , Proteínas Represoras/metabolismo , Empalme del ARN , ARN Mensajero/genética , ARN Mensajero/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Respuesta de Proteína Desplegada/genética , Estrés del Retículo Endoplásmico
8.
Nature ; 430(6995): 35-44, 2004 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-15229592

RESUMEN

Identifying the mechanisms of eukaryotic genome evolution by comparative genomics is often complicated by the multiplicity of events that have taken place throughout the history of individual lineages, leaving only distorted and superimposed traces in the genome of each living organism. The hemiascomycete yeasts, with their compact genomes, similar lifestyle and distinct sexual and physiological properties, provide a unique opportunity to explore such mechanisms. We present here the complete, assembled genome sequences of four yeast species, selected to represent a broad evolutionary range within a single eukaryotic phylum, that after analysis proved to be molecularly as diverse as the entire phylum of chordates. A total of approximately 24,200 novel genes were identified, the translation products of which were classified together with Saccharomyces cerevisiae proteins into about 4,700 families, forming the basis for interspecific comparisons. Analysis of chromosome maps and genome redundancies reveal that the different yeast lineages have evolved through a marked interplay between several distinct molecular mechanisms, including tandem gene repeat formation, segmental duplication, a massive genome duplication and extensive gene loss.


Asunto(s)
Evolución Molecular , Genes Fúngicos/genética , Genoma Fúngico , Levaduras/clasificación , Levaduras/genética , Cromosomas Fúngicos/genética , Secuencia Conservada/genética , Duplicación de Gen , Datos de Secuencia Molecular , ARN Ribosómico/genética , ARN de Transferencia/genética , Proteínas de Saccharomyces cerevisiae/genética , Sintenía/genética , Secuencias Repetidas en Tándem/genética
9.
Nucleus ; 8(5): 482-488, 2017 09 03.
Artículo en Inglés | MEDLINE | ID: mdl-28816581

RESUMEN

The first step of gene expression results in the production of mRNA ribonucleoparticles (mRNPs) that are exported to the cytoplasm via the NPC for translation into the cytoplasm. During this process, the mRNA molecule synthesized by RNA polymerase II (Pol II) undergoes extensive maturation, folding and packaging events that are intimately coupled to its synthesis. All these events take place in a chromatin context and it is therefore not surprising that a growing number of studies recently reported specific contributions of chromatin dynamics to various steps of mRNP biogenesis. In this extra view, we replace our recent findings highlighting the contribution of the yeast chromatin remodeling complex ISW1 to nuclear mRNA quality control in the context of the recent literature.


Asunto(s)
Cromatina/metabolismo , Transcripción Genética , Animales , Cromatina/genética , Ensamble y Desensamble de Cromatina , Histonas/metabolismo , Humanos , Empalme del ARN , ARN Mensajero/biosíntesis , ARN Mensajero/genética
10.
J Cell Biol ; 196(1): 19-27, 2012 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-22213798

RESUMEN

Nuclear pore complexes (NPCs) correspond to large protein transport complexes responsible for selective nucleocytoplasmic exchange. Although research has revealed much about the molecular architecture and roles of the NPC subcomplexes, little is known about the regulation of NPC functions by posttranslational modifications. We used a systematic approach to show that more than half of NPC proteins were conjugated to ubiquitin. In particular, Nup159, a nucleoporin exclusively located on the cytoplasmic side of the NPC, was monoubiquitylated by the Cdc34/SCF (Skp1-Cdc53-F-box E3 ligase) enzymes. Preventing this modification had no consequences on nuclear transport or NPC organization but strongly affected the ability of Nup159 to target the dynein light chain to the NPC. This led to defects in nuclear segregation at the onset of mitosis. Thus, defining ubiquitylation of the yeast NPC highlights yet-unexplored functions of this essential organelle in cell division.


Asunto(s)
Mitosis , Poro Nuclear/fisiología , Saccharomyces cerevisiae/citología , Ubiquitinación , Transporte Activo de Núcleo Celular , Ciclosoma-Complejo Promotor de la Anafase , Núcleo Celular/fisiología , Dineínas Citoplasmáticas/metabolismo , Poro Nuclear/metabolismo , Proteínas de Complejo Poro Nuclear/genética , Proteínas de Complejo Poro Nuclear/metabolismo , Proteínas de Complejo Poro Nuclear/fisiología , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/ultraestructura , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/fisiología , Enzimas Ubiquitina-Conjugadoras , Complejos de Ubiquitina-Proteína Ligasa/metabolismo
11.
Cell Logist ; 2(1): 43-45, 2012 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-22645709

RESUMEN

Covalent attachment of ubiquitin to target proteins, or ubiquitylation, has emerged as one of the most prevalent posttranslational modifications (PTMs), regulating nearly every cellular pathway. The diversity of functions associated with this particular PTM stems from the myriad ways in which a target protein can be modified by ubiquitin, e.g., monoubiquitin, multi-monoubiquitin, and polyubiquitin linkages. In the current study, we took a systematic approach to analyze the ubiquitylation profiles of the yeast Saccharomyces cerevisiae nuclear pore complex (NPC) proteins or nucleoporins. We found the yeast NPC to be extensively modified by ubiquitin with highly variable ubiquitylation profiles, suggesting that dissection of these modifications may provide new insights into the regulation of NPC functions and reveal additional roles for nucleoporins beyond nuclear transport.

12.
Curr Genet ; 53(6): 337-46, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18421459

RESUMEN

Following endoplasmic reticulum (ER) stress, eukaryotic cells trigger a conserved signal transduction pathway called the unfolded protein response (UPR) that regulates the ER's capacity to perform protein folding according to cellular demand. In Saccharomyces cerevisiae, the UPR is initiated by Ire1, a type I transmembrane serine/threonine kinase/endoribonuclease, that senses unfolded protein levels within the ER in collaboration with the ER Hsp70-family member, BiP/Kar2. Here, we report on the characterization of the Yarrowia lipolytica Ire1 ortholog. Our results show that Sls1, a nucleotide exchange factor for BiP, has important functions in regulating ER stress and the interaction of BiP and Ire1. They suggest that Sls1 regulates this interaction, by stimulating the conversion of BiP from the ADP-bound to the ATP-bound state, which favors its interaction with Ire1. Moreover, we identified known and new partners for Ire1 using the Tandem Affinity Purification (TAP) approach.


Asunto(s)
Proteínas Portadoras/metabolismo , Endorribonucleasas/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Yarrowia/metabolismo , Secuencia de Aminoácidos , Proteínas Portadoras/genética , Proteínas Fúngicas/genética , Regulación Fúngica de la Expresión Génica , Genes Fúngicos , Datos de Secuencia Molecular , Nucleótidos/genética , Nucleótidos/metabolismo , Pliegue de Proteína , Alineación de Secuencia , Yarrowia/enzimología , Yarrowia/genética
13.
J Cell Sci ; 115(Pt 24): 4947-56, 2002 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-12432081

RESUMEN

The core component of the translocation apparatus, Sec61p or alpha, was previously cloned in Yarrowia lipolytica. Using anti-Sec61p antibodies, we showed that most of the translocation sites are devoted to co-translational translocation in this yeast, which is similar to the situation in mammalian cells but in contrast to the situation in Saccharomyces cerevisiae, where post-translational translocation is predominant. In order to characterize further the minimal translocation apparatus in Y. lipolytica, the beta Sec61 complex subunit, Sbh1p, was cloned by functional complementation of a Deltasbh1, Deltasbh2 S. cerevisiae mutant. The secretion of the reporter protein is not impaired in the Y. lipolytica sbh1 inactivated strain. We screened the Y. lipolytica two-hybrid library to look for partners of this translocon component. The ER-membrane chaperone protein, calnexin, was identified as an interacting protein. By a co-immunoprecipitation approach, we confirmed this association in Yarrowia and then showed that the S. cerevisiae Sbh2p protein was a functional homologue of YlSbh1p. The interaction of Sbh1p with calnexin was shown to occur between the lumenal domain of both proteins. These results suggest that the beta subunit of the Sec61 translocon may relay folding of nascent proteins to their translocation.


Asunto(s)
Calnexina/metabolismo , Proteínas de la Membrana/metabolismo , Chaperonas Moleculares/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Yarrowia/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , Cartilla de ADN , ADN Complementario , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Unión Proteica , Pliegue de Proteína , Canales de Translocación SEC , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Homología de Secuencia de Aminoácido , Técnicas del Sistema de Dos Híbridos , Proteínas de Transporte Vesicular
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA