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1.
Mol Cell ; 78(1): 127-140.e7, 2020 04 02.
Artículo en Inglés | MEDLINE | ID: mdl-32035037

RESUMEN

As cells enter mitosis, the genome is restructured to facilitate chromosome segregation, accompanied by dramatic changes in gene expression. However, the mechanisms that underlie mitotic transcriptional regulation are unclear. In contrast to transcribed genes, centromere regions retain transcriptionally active RNA polymerase II (Pol II) in mitosis. Here, we demonstrate that chromatin-bound cohesin is necessary to retain elongating Pol II at centromeres. We find that WAPL-mediated removal of cohesin from chromosome arms during prophase is required for the dissociation of Pol II and nascent transcripts, and failure of this process dramatically alters mitotic gene expression. Removal of cohesin/Pol II from chromosome arms in prophase is important for accurate chromosome segregation and normal activation of gene expression in G1. We propose that prophase cohesin removal is a key step in reprogramming gene expression as cells transition from G2 through mitosis to G1.


Asunto(s)
Proteínas de Ciclo Celular/fisiología , Proteínas Cromosómicas no Histona/fisiología , Regulación de la Expresión Génica , Mitosis/genética , Transcripción Genética , Anafase/genética , Animales , Aurora Quinasa B/análisis , Ciclo Celular , Proteínas de Ciclo Celular/análisis , Línea Celular , Centrómero/enzimología , Segregación Cromosómica , Fase G1/genética , Puntos de Control de la Fase G2 del Ciclo Celular/genética , Humanos , Metafase/genética , Profase , ARN Polimerasa II/metabolismo , Xenopus laevis , Cohesinas
2.
J Biol Chem ; 296: 100202, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33334895

RESUMEN

Elongin A (EloA) is an essential transcription factor that stimulates the rate of RNA polymerase II (Pol II) transcription elongation in vitro. However, its role as a transcription factor in vivo has remained underexplored. Here we show that in mouse embryonic stem cells, EloA localizes to both thousands of Pol II transcribed genes with preference for transcription start site and promoter regions and a large number of active enhancers across the genome. EloA deletion results in accumulation of transcripts from a subset of enhancers and their adjacent genes. Notably, EloA does not substantially enhance the elongation rate of Pol II in vivo. We also show that EloA localizes to the nucleoli and associates with RNA polymerase I transcribed ribosomal RNA gene, Rn45s. EloA is a highly disordered protein, which we demonstrate forms phase-separated condensates in vitro, and truncation mutations in the intrinsically disordered regions (IDR) of EloA interfere with its targeting and localization to the nucleoli. We conclude that EloA broadly associates with transcribed regions, tunes RNA Pol II transcription levels via impacts on enhancer RNA synthesis, and interacts with the rRNA producing/processing machinery in the nucleolus. Our work opens new avenues for further investigation of the role of this functionally multifaceted transcription factor in enhancer and ribosomal RNA biology.


Asunto(s)
Elonguina/metabolismo , Elementos de Facilitación Genéticos , Células Madre Embrionarias de Ratones/metabolismo , ARN/genética , Activación Transcripcional , Animales , Línea Celular , Elonguina/genética , Eliminación de Gen , Ratones , ARN Polimerasa II/genética , ARN Polimerasa II/metabolismo , Sitio de Iniciación de la Transcripción
3.
RNA ; 26(3): 324-344, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31896558

RESUMEN

Most cells change patterns of gene expression through transcriptional regulation. In contrast, oocytes are transcriptionally silent and regulate mRNA poly(A) tail length to control protein production. However, the genome-wide relationship of poly(A) tail changes to mRNA translation during vertebrate oocyte maturation is not known. We used Tail-seq and polyribosome analysis to measure poly(A) tail and translational changes during oocyte maturation in Xenopus laevis We identified large-scale poly(A) and translational changes during oocyte maturation, with poly(A) tail length changes preceding translational changes. Proteins important for completion of the meiotic divisions and early development exhibited increased polyadenylation and translation during oocyte maturation. A family of U-rich sequence elements was enriched near the polyadenylation signal of polyadenylated and translationally activated mRNAs. We propose that changes in mRNA polyadenylation are a conserved mechanism regulating protein expression during vertebrate oocyte maturation and that these changes are controlled by a spatial code of cis-acting sequence elements.


Asunto(s)
Oogénesis/genética , Poliadenilación/genética , Biosíntesis de Proteínas/genética , ARN Mensajero/genética , Animales , Regulación del Desarrollo de la Expresión Génica/genética , Genoma/genética , Oocitos/crecimiento & desarrollo , Oocitos/metabolismo , Secuencias Reguladoras de Ácidos Nucleicos/genética , Xenopus laevis/genética , Xenopus laevis/crecimiento & desarrollo
4.
J Biol Chem ; 293(32): 12593-12605, 2018 08 10.
Artículo en Inglés | MEDLINE | ID: mdl-29903915

RESUMEN

RNA-binding proteins (RBP) are critical regulators of gene expression. Recent studies have uncovered hundreds of mRNA-binding proteins that do not contain annotated RNA-binding domains and have well-established roles in other cellular processes. Investigation of these nonconventional RBPs is critical for revealing novel RNA-binding domains and may disclose connections between RNA regulation and other aspects of cell biology. The endosomal sorting complex required for transport II (ESCRT-II) is a nonconventional RNA-binding complex that has a canonical role in multivesicular body formation. ESCRT-II was identified previously as an RNA-binding complex in Drosophila oocytes, but whether its RNA-binding properties extend beyond Drosophila is unknown. In this study, we found that the RNA-binding properties of ESCRT-II are conserved in Xenopus eggs, where ESCRT-II interacted with hundreds of mRNAs. Using a UV cross-linking approach, we demonstrated that ESCRT-II binds directly to RNA through its subunit, Vps25. UV cross-linking and immunoprecipitation (CLIP)-Seq revealed that Vps25 specifically recognizes a polypurine (i.e. GA-rich) motif in RNA. Using purified components, we could reconstitute the selective Vps25-mediated binding of the polypurine motif in vitro Our results provide insight into the mechanism by which ESCRT-II selectively binds to mRNA and also suggest an unexpected link between endosome biology and RNA regulation.


Asunto(s)
Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Óvulo/metabolismo , Purinas/metabolismo , Proteínas de Unión al ARN/metabolismo , ARN/metabolismo , Xenopus laevis/metabolismo , Animales , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Femenino , Subunidades de Proteína , Purinas/química , ARN/química , ARN/genética , Proteínas de Unión al ARN/genética , Xenopus laevis/genética
5.
RNA ; 23(4): 504-520, 2017 04.
Artículo en Inglés | MEDLINE | ID: mdl-28031481

RESUMEN

Piwi proteins utilize small RNAs (piRNAs) to recognize target transcripts such as transposable elements (TE). However, extensive piRNA sequence diversity also suggests that Piwi/piRNA complexes interact with many transcripts beyond TEs. To determine Piwi target RNAs, we used ribonucleoprotein-immunoprecipitation (RIP) and cross-linking and immunoprecipitation (CLIP) to identify thousands of transcripts associated with the Piwi proteins XIWI and XILI (Piwi-protein-associated transcripts, PATs) from early stage oocytes of X. laevis and X. tropicalis Most PATs associate with both XIWI and XILI and include transcripts of developmentally important proteins in oogenesis and embryogenesis. Only a minor fraction of PATs in both frog species displayed near perfect matches to piRNAs. Since predicting imperfect pairing between all piRNAs and target RNAs remains intractable, we instead determined that PAT read counts correlate well with the lengths and expression levels of transcripts, features that have also been observed for oocyte mRNAs associated with Drosophila Piwi proteins. We used an in vitro assay with exogenous RNA to confirm that XIWI associates with RNAs in a length- and concentration-dependent manner. In this assay, noncoding transcripts with many perfectly matched antisense piRNAs were unstable, whereas coding transcripts with matching piRNAs were stable, consistent with emerging evidence that Piwi proteins both promote the turnover of TEs and other RNAs, and may also regulate mRNA localization and translation. Our study suggests that Piwi proteins play multiple roles in germ cells and establishes a tractable vertebrate system to study the role of Piwi proteins in transcript regulation.


Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Oocitos/metabolismo , ARN Interferente Pequeño/genética , Transcriptoma , Proteínas de Xenopus/genética , Xenopus/genética , Animales , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Bioensayo , Elementos Transponibles de ADN , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Desarrollo Embrionario/genética , Femenino , Oocitos/crecimiento & desarrollo , Oogénesis/genética , Filogenia , Unión Proteica , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Interferente Pequeño/metabolismo , Xenopus/clasificación , Xenopus/crecimiento & desarrollo , Xenopus/metabolismo , Proteínas de Xenopus/metabolismo
6.
Genes Dev ; 25(11): 1159-72, 2011 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-21576258

RESUMEN

Variants in the IMP2 (insulin-like growth factor 2 [IGF2] mRNA-binding protein 2) gene are implicated in susceptibility to type 2 diabetes. We describe the ability of mammalian target of rapamycin (mTOR) to regulate the cap-independent translation of IGF2 mRNA through phosphorylation of IMP2, an oncofetal RNA-binding protein. IMP2 is doubly phosphorylated in a rapamycin-inhibitable, amino acid-dependent manner in cells and by mTOR in vitro. Double phosphorylation promotes IMP2 binding to the IGF2 leader 3 mRNA 5' untranslated region, and the translational initiation of this mRNA through eIF-4E- and 5' cap-independent internal ribosomal entry. Unexpectedly, the interaction of IMP2 with mTOR complex 1 occurs through mTOR itself rather than through raptor. Whereas depletion of mTOR strongly inhibits IMP2 phosphorylation in cells, comparable depletion of raptor has no effect; moreover, the ability of mTOR to phosphorylate IMP2 in vitro is unaffected by the elimination of raptor. Dual phosphorylation of IMP2 at the mTOR sites is evident in the mouse embryo, likely coupling nutrient sufficiency to IGF2 expression and fetal growth. Doubly phosphorylated IMP2 is also widely expressed in adult tissues, including islets of Langerhans.


Asunto(s)
Regulación de la Expresión Génica , Factor II del Crecimiento Similar a la Insulina/metabolismo , Proteínas de Unión al ARN/metabolismo , Ribosomas/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Regiones no Traducidas 5' , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Antibacterianos/farmacología , Línea Celular , Regulación de la Expresión Génica/efectos de los fármacos , Células HEK293 , Humanos , Factor II del Crecimiento Similar a la Insulina/genética , Ratones , Mutación , Fosforilación , Unión Proteica/efectos de los fármacos , Unión Proteica/genética , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/genética , Proteína Reguladora Asociada a mTOR , Transducción de Señal , Sirolimus/farmacología
7.
RNA ; 21(2): 279-95, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25519486

RESUMEN

ADAR (adenosine deaminase acting on RNA) is an RNA-editing enzyme present in most metazoans that converts adenosines in double-stranded RNA targets into inosines. Although the RNA targets of ADAR-mediated editing have been extensively cataloged, our understanding of the cellular function of such editing remains incomplete. We report that long, double-stranded RNA added to Xenopus laevis egg extract is incorporated into an ADAR-containing complex whose protein components resemble those of stress granules. This complex localizes to microtubules, as assayed by accumulation on meiotic spindles. We observe that the length of a double-stranded RNA influences its incorporation into the microtubule-localized complex. ADAR forms a similar complex with endogenous RNA, but the endogenous complex fails to localize to microtubules. In addition, we characterize the endogenous, ADAR-associated RNAs and discover that they are enriched for transcripts encoding transcriptional regulators, zinc-finger proteins, and components of the secretory pathway. Interestingly, association with ADAR correlates with previously reported translational repression in early embryonic development. This work demonstrates that ADAR is a component of two, distinct ribonucleoprotein complexes that contain different types of RNAs and exhibit diverse cellular localization patterns. Our findings offer new insight into the potential cellular functions of ADAR.


Asunto(s)
Adenosina Desaminasa/metabolismo , ARN Bicatenario/metabolismo , Proteínas de Xenopus/metabolismo , Animales , Oocitos/enzimología , Transporte de ARN , Ribonucleoproteínas/metabolismo , Huso Acromático/metabolismo , Xenopus laevis
8.
Cell Mol Life Sci ; 73(1): 79-94, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26433683

RESUMEN

The endoplasmic reticulum (ER) is a large, dynamic structure that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism. The diverse functions of the ER are performed by distinct domains; consisting of tubules, sheets and the nuclear envelope. Several proteins that contribute to the overall architecture and dynamics of the ER have been identified, but many questions remain as to how the ER changes shape in response to cellular cues, cell type, cell cycle state and during development of the organism. Here we discuss what is known about the dynamics of the ER, what questions remain, and how coordinated responses add to the layers of regulation in this dynamic organelle.


Asunto(s)
Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/ultraestructura , Animales , Calcio/metabolismo , Retículo Endoplásmico/química , Fertilización , Humanos , Metabolismo de los Lípidos , Mitosis , Biosíntesis de Proteínas , Pliegue de Proteína , Proteínas/química , Proteínas/metabolismo , Transducción de Señal , Respuesta de Proteína Desplegada
9.
Proc Natl Acad Sci U S A ; 111(24): 8985-90, 2014 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-24889638

RESUMEN

The mitochondrial calcium uniporter is a highly selective calcium channel distributed broadly across eukaryotes but absent in the yeast Saccharomyces cerevisiae. The molecular components of the human uniporter holocomplex (uniplex) have been identified recently. The uniplex consists of three membrane-spanning subunits--mitochondrial calcium uniporter (MCU), its paralog MCUb, and essential MCU regulator (EMRE)--and two soluble regulatory components--MICU1 and its paralog MICU2. The minimal components sufficient for in vivo uniporter activity are unknown. Here we consider Dictyostelium discoideum (Dd), a member of the Amoebazoa outgroup of Metazoa and Fungi, and show that it has a highly simplified uniporter machinery. We show that D. discoideum mitochondria exhibit membrane potential-dependent calcium uptake compatible with uniporter activity, and also that expression of DdMCU complements the mitochondrial calcium uptake defect in human cells lacking MCU or EMRE. Moreover, expression of DdMCU in yeast alone is sufficient to reconstitute mitochondrial calcium uniporter activity. Having established yeast as an in vivo reconstitution system, we then reconstituted the human uniporter. We show that coexpression of MCU and EMRE is sufficient for uniporter activity, whereas expression of MCU alone is insufficient. Our work establishes yeast as a powerful in vivo reconstitution system for the uniporter. Using this system, we confirm that MCU is the pore-forming subunit, define the minimal genetic elements sufficient for metazoan and nonmetazoan uniporter activity, and provide valuable insight into the evolution of the uniporter machinery.


Asunto(s)
Canales de Calcio/química , Calcio/química , Mitocondrias/metabolismo , Saccharomyces cerevisiae/metabolismo , Calcio/metabolismo , Línea Celular , Dictyostelium , Técnicas Genéticas , Células HEK293 , Humanos , Membranas Intracelulares/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/metabolismo
10.
bioRxiv ; 2024 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-39314300

RESUMEN

SAF-A is conserved throughout vertebrates and has emerged as an important factor regulating a multitude of nuclear functions, including lncRNA localization, gene expression, and splicing. SAF-A has several functional domains, including an N-terminal SAP domain that binds directly to DNA. Phosphorylation of SAP domain serines S14 and S26 are important for SAF-A localization and function during mitosis, however whether these serines are involved in interphase functions of SAF-A is not known. In this study we tested for the role of the SAP domain, and SAP domain serines S14 and S26 in X chromosome inactivation, protein dynamics, gene expression, splicing, and cell proliferation. Here we show that the SAP domain serines S14 and S26 are required to maintain XIST RNA localization and polycomb-dependent histone modifications on the inactive X chromosome in female cells. In addition, we present evidence that an Xi localization signal resides in the SAP domain. We found that that the SAP domain is not required to maintain gene expression and plays only a minor role in mRNA splicing. In contrast, the SAF-A SAP domain, in particular serines S14 and S26, are required for normal protein dynamics, and to maintain normal cell proliferation. We propose a model whereby dynamic phosphorylation of SAF-A serines S14 and S26 mediates rapid turnover of SAF-A interactions with DNA during interphase.

11.
EMBO J ; 28(19): 2945-58, 2009 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-19713941

RESUMEN

Piwi proteins and Piwi-interacting RNAs (piRNAs) are essential for germ cell development, but analysis of the molecular mechanisms of these ribonucleoproteins remains challenging in most animal germ cells. To address this challenge, we systematically characterized Xiwi, a Xenopus Piwi homologue, and piRNAs from Xenopus eggs and oocytes. We used the large size of Xenopus eggs to analyze small RNAs at the single cell level, and find abundant piRNAs and large piRNA clusters in the Xenopus tropicalis genome, some of which resemble the Drosophila piRNA-generating flamenco locus. Although most piRNA clusters are expressed simultaneously in an egg, individual frogs show distinct profiles of cluster expression. Xiwi is associated with microtubules and the meiotic spindle, and is localized to the germ plasm--a cytoplasmic determinant of germ cell formation. Xiwi associates with translational regulators in an RNA-dependent manner, but Xenopus tudor interacts with Xiwi independently of RNA. Our study adds insight to piRNA transcription regulation by showing that individual animals can have differential piRNA expression profiles. We suggest that in addition to regulating transposable elements, Xiwi may function in specifying RNA localization in vertebrate oocytes.


Asunto(s)
Óvulo/metabolismo , ARN Interferente Pequeño/genética , Xenopus/genética , Animales , Drosophila/genética , Meiosis , Proteínas Asociadas a Microtúbulos/análisis , Proteínas Asociadas a Microtúbulos/metabolismo , Oocitos/citología , Oocitos/metabolismo , Oogénesis , Biosíntesis de Proteínas , ARN Interferente Pequeño/metabolismo , Xenopus/embriología , Xenopus/metabolismo , Proteínas de Xenopus/análisis , Proteínas de Xenopus/metabolismo
12.
Mol Biol Cell ; 34(4): ar32, 2023 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-36790906

RESUMEN

Mitosis results in a dramatic reorganization of chromatin structure to promote chromosome compaction and segregation to daughter cells. Consequently, mitotic entry is accompanied by transcriptional silencing and removal of most chromatin-bound RNA from chromosomes. As cells exit mitosis, chromatin rapidly decondenses and transcription restarts as waves of differential gene expression. However, little is known about the fate of chromatin-bound RNAs following cell division. Here we explored whether nuclear RNA from the previous cell cycle is present in G1 nuclei following mitosis. We found that half of all nuclear RNA is inherited in a transcription-independent manner following mitosis. Interestingly, the snRNA U2 is efficiently inherited by G1 nuclei, while the lncRNAs NEAT1 and MALAT1 show no inheritance following mitosis. We found that the nuclear protein SAF-A, which is hypothesized to tether RNA to DNA, did not play a prominent role in nuclear RNA inheritance, indicating that the mechanism for RNA inheritance may not involve RNA chaperones that have chromatin-binding activity. Instead, we observe that the timing of RNA inheritance indicates that a select group of nuclear RNAs are reimported into the nucleus after the nuclear envelope has reassembled. Our work demonstrates that there is a fraction of nuclear RNA from the previous cell cycle that is reimported following mitosis and suggests that mitosis may serve as a time to reset the interaction of lncRNAs with chromatin.


Asunto(s)
ARN Largo no Codificante , ARN Nuclear , Transporte Activo de Núcleo Celular , ARN Nuclear/metabolismo , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Mitosis , Cromatina
13.
J Cell Biol ; 176(6): 765-70, 2007 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-17339377

RESUMEN

The African clawed frog Xenopus laevis has been instrumental to investigations of both development and cell biology, but the utility of this model organism for genetic and proteomic studies is limited by its long generation time and unsequenced pseudotetraploid genome. Xenopus tropicalis, which is a small, faster-breeding relative of X. laevis, has recently been adopted for research in developmental genetics and functional genomics, and has been chosen for genome sequencing. We show that X. tropicalis egg extracts reconstitute the fundamental cell cycle events of nuclear formation and bipolar spindle assembly around exogenously added sperm nuclei. Interestingly, X. tropicalis spindles were approximately 30% shorter than X. laevis spindles, and mixing experiments revealed a dynamic, dose-dependent regulation of spindle size by cytoplasmic factors. Measurements of microtubule dynamics revealed that microtubules polymerized slower in X. tropicalis extracts compared to X. laevis, but that this difference is unlikely to account for differences in spindle size. Thus, in addition to expanding the range of developmental and cell biological experiments, the use of X. tropicalis provides novel insight into the complex mechanisms that govern spindle morphogenesis.


Asunto(s)
Óvulo/química , Huso Acromático/ultraestructura , Animales , Extractos Celulares/química , Microtúbulos/metabolismo , Microtúbulos/ultraestructura , Óvulo/ultraestructura , Huso Acromático/metabolismo , Xenopus
14.
Dev Cell ; 10(3): 303-15, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16516834

RESUMEN

The centromere-specific histone variant CENP-A (CID in Drosophila) is a structural and functional foundation for kinetochore formation and chromosome segregation. Here, we show that overexpressed CID is mislocalized into normally noncentromeric regions in Drosophila tissue culture cells and animals. Analysis of mitoses in living and fixed cells reveals that mitotic delays, anaphase bridges, chromosome fragmentation, and cell and organismal lethality are all direct consequences of CID mislocalization. In addition, proteins that are normally restricted to endogenous kinetochores assemble at a subset of ectopic CID incorporation regions. The presence of microtubule motors and binding proteins, spindle attachments, and aberrant chromosome morphologies demonstrate that these ectopic kinetochores are functional. We conclude that CID mislocalization promotes formation of ectopic centromeres and multicentric chromosomes, which causes chromosome missegregation, aneuploidy, and growth defects. Thus, CENP-A mislocalization is one possible mechanism for genome instability during cancer progression, as well as centromere plasticity during evolution.


Asunto(s)
Centrómero/metabolismo , Proteínas de Unión al ADN/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Histonas/metabolismo , Cinetocoros/metabolismo , Animales , Animales Modificados Genéticamente , Proteínas de Ciclo Celular/metabolismo , Proteína A Centromérica , Proteínas Cromosómicas no Histona/metabolismo , Segregación Cromosómica , Proteínas de Unión al ADN/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/anatomía & histología , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/fisiología , Histonas/genética , Larva/anatomía & histología , Larva/fisiología , Microtúbulos/metabolismo , Mitosis/fisiología , Proteínas Motoras Moleculares/metabolismo , Fenotipo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo
15.
Trends Cell Biol ; 31(9): 760-773, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-33766521

RESUMEN

Beyond its originally discovered role tethering replicated sister chromatids, cohesin has emerged as a master regulator of gene expression. Recent advances in chromatin topology resolution and single-cell studies have revealed that cohesin has a pivotal role regulating highly dynamic chromatin interactions linked to transcription control. The dynamic association of cohesin with chromatin and its capacity to perform loop extrusion contribute to the heterogeneity of chromatin contacts. Additionally, different cohesin subcomplexes, with specific properties and regulation, control gene expression across the cell cycle and during developmental cell commitment. Here, we discuss the most recent literature in the field to highlight the role of cohesin in gene expression regulation during transcriptional shifts and its relationship with human diseases.


Asunto(s)
Proteínas de Ciclo Celular , Proteínas Cromosómicas no Histona , Proteínas de Ciclo Celular/genética , Cromátides , Cromatina/genética , Proteínas Cromosómicas no Histona/genética , Expresión Génica , Humanos , Cohesinas
16.
J Cell Biol ; 219(11)2020 11 02.
Artículo en Inglés | MEDLINE | ID: mdl-33053167

RESUMEN

During mitosis, the genome is transformed from a decondensed, transcriptionally active state to a highly condensed, transcriptionally inactive state. Mitotic chromosome reorganization is marked by the general attenuation of transcription on chromosome arms, yet how the cell regulates nuclear and chromatin-associated RNAs after chromosome condensation and nuclear envelope breakdown is unknown. SAF-A/hnRNPU is an abundant nuclear protein with RNA-to-DNA tethering activity, coordinated by two spatially distinct nucleic acid-binding domains. Here we show that RNA is evicted from prophase chromosomes through Aurora-B-dependent phosphorylation of the SAF-A DNA-binding domain; failure to execute this pathway leads to accumulation of SAF-A-RNA complexes on mitotic chromosomes, defects in metaphase chromosome alignment, and elevated rates of chromosome missegregation in anaphase. This work reveals a role for Aurora-B in removing chromatin-associated RNAs during prophase and demonstrates that Aurora-B-dependent relocalization of SAF-A during cell division contributes to the fidelity of chromosome segregation.


Asunto(s)
Aurora Quinasa B/metabolismo , Núcleo Celular/genética , Cromatina/química , Cromosomas Humanos/química , Ribonucleoproteína Heterogénea-Nuclear Grupo U/metabolismo , Mitosis , ARN/metabolismo , Aurora Quinasa B/genética , Cromatina/genética , Cromosomas Humanos/genética , Células HEK293 , Ribonucleoproteína Heterogénea-Nuclear Grupo U/genética , Humanos , Fosforilación , ARN/genética
17.
Dev Cell ; 2(3): 319-30, 2002 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11879637

RESUMEN

Recent studies have highlighted the importance of centromere-specific histone H3-like (CENP-A) proteins in centromere function. We show that Drosophila CID and human CENP-A appear at metaphase as a three-dimensional structure that lacks histone H3. However, blocks of CID/CENP-A and H3 nucleosomes are linearly interspersed on extended chromatin fibers, and CID is close to H3 nucleosomes in polynucleosomal preparations. When CID is depleted by RNAi, it is replaced by H3, demonstrating flexibility of centromeric chromatin organization. Finally, contrary to models proposing that H3 and CID/CENP-A nucleosomes are replicated at different times in S phase, we show that interspersed H3 and CID/CENP-A chromatin are replicated concurrently during S phase in humans and flies. We propose that the unique structural arrangement of CID/CENP-A and H3 nucleosomes presents centromeric chromatin to the poleward face of the condensing mitotic chromosome.


Asunto(s)
Autoantígenos , Cromatina/química , Cromatina/fisiología , Proteínas de Drosophila , Cinetocoros/química , Cinetocoros/fisiología , Animales , Proteína A Centromérica , Proteínas Cromosómicas no Histona/análisis , Cromosomas/química , Cromosomas/fisiología , Proteínas de Unión al ADN , Drosophila , Evolución Molecular , Histonas/análisis , Histonas/metabolismo , Humanos , Metafase/fisiología , Nucleosomas/química , Fosforilación , Estructura Terciaria de Proteína
18.
PLoS Genet ; 2(7): e110, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16839185

RESUMEN

The centromere/kinetochore complex plays an essential role in cell and organismal viability by ensuring chromosome movements during mitosis and meiosis. The kinetochore also mediates the spindle attachment checkpoint (SAC), which delays anaphase initiation until all chromosomes have achieved bipolar attachment of kinetochores to the mitotic spindle. CENP-A proteins are centromere-specific chromatin components that provide both a structural and a functional foundation for kinetochore formation. Here we show that cells in Drosophila embryos homozygous for null mutations in CENP-A (CID) display an early mitotic delay. This mitotic delay is not suppressed by inactivation of the DNA damage checkpoint and is unlikely to be the result of DNA damage. Surprisingly, mutation of the SAC component BUBR1 partially suppresses this mitotic delay. Furthermore, cid mutants retain an intact SAC response to spindle disruption despite the inability of many kinetochore proteins, including SAC components, to target to kinetochores. We propose that SAC components are able to monitor spindle assembly and inhibit cell cycle progression in the absence of sustained kinetochore localization.


Asunto(s)
Proteínas de Ciclo Celular/genética , Proteínas de Unión al ADN/genética , Proteínas de Drosophila/genética , Histonas/genética , Cinetocoros/metabolismo , Mitosis , Mutación , Huso Acromático , Alelos , Animales , Proteína A Centromérica , Daño del ADN , Drosophila , Heterocigoto , Modelos Genéticos , Fenotipo
19.
Mol Cell Biol ; 38(18)2018 09 15.
Artículo en Inglés | MEDLINE | ID: mdl-29941491

RESUMEN

Accurate chromosome segregation is a fundamental process in cell biology. During mitosis, chromosomes are segregated into daughter cells through interactions between centromeres and microtubules in the mitotic spindle. Centromere domains have evolved to nucleate formation of the kinetochore, which is essential for establishing connections between chromosomal DNA and microtubules during mitosis. Centromeres are typically formed on highly repetitive DNA that is not conserved in sequence or size among organisms and can differ substantially between individuals within the same organism. However, transcription of repetitive DNA has emerged as a highly conserved property of the centromere. Recent work has shown that both the topological effect of transcription on chromatin and the nascent noncoding RNAs contribute to multiple aspects of centromere function. In this review, we discuss the fundamental aspects of centromere transcription, i.e., its dual role in chromatin remodeling/CENP-A deposition and kinetochore assembly during mitosis, from a cell cycle perspective.


Asunto(s)
Centrómero/genética , Centrómero/metabolismo , Transcripción Genética , Animales , Aurora Quinasa B/metabolismo , Proteína A Centromérica/metabolismo , Ensamble y Desensamble de Cromatina , Segregación Cromosómica , ADN/genética , ADN/metabolismo , Humanos , Cinetocoros/metabolismo , Mitosis , Modelos Genéticos , ARN Polimerasa II/metabolismo , ARN Nuclear/genética , ARN Nuclear/metabolismo
20.
Dev Cell ; 42(3): 201-202, 2017 08 07.
Artículo en Inglés | MEDLINE | ID: mdl-28787584

RESUMEN

Centromeric transcription is a common eukaryotic centromere feature, yet it is unclear how transcription is linked to underlying repetitive satellite sequences. In this issue of Developmental Cell, McNulty et al. (2017) show for human centromeres that all α-satellite sequences are transcribed into chromatin-bound RNAs and are required for centromere assembly.


Asunto(s)
Centrómero , Cromatina , ADN Satélite , Humanos , Secuencias Repetitivas de Ácidos Nucleicos
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