RÉSUMÉ
Two different models have been proposed to explain how the endpoints of chromatin looped domains ('TADs') in eukaryotic chromosomes are determined. In the first, a cohesin complex extrudes a loop until it encounters a boundary element roadblock, generating a stem-loop. In this model, boundaries are functionally autonomous: they have an intrinsic ability to halt the movement of incoming cohesin complexes that is independent of the properties of neighboring boundaries. In the second, loops are generated by boundary:boundary pairing. In this model, boundaries are functionally non-autonomous, and their ability to form a loop depends upon how well they match with their neighbors. Moreover, unlike the loop-extrusion model, pairing interactions can generate both stem-loops and circle-loops. We have used a combination of MicroC to analyze how TADs are organized, and experimental manipulations of the even skipped TAD boundary, homie, to test the predictions of the 'loop-extrusion' and the 'boundary-pairing' models. Our findings are incompatible with the loop-extrusion model, and instead suggest that the endpoints of TADs in flies are determined by a mechanism in which boundary elements physically pair with their partners, either head-to-head or head-to-tail, with varying degrees of specificity. Although our experiments do not address how partners find each other, the mechanism is unlikely to require loop extrusion.
Sujet(s)
Drosophila , Animaux , Drosophila/génétique , Drosophila melanogaster/génétique , Chromatine/composition chimique , Chromatine/métabolisme , , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/composition chimique , Protéines chromosomiques nonhistones/génétique , Structures de chromosome , Protéines du cycle cellulaire/métabolisme , Protéines du cycle cellulaire/génétique , Protéines du cycle cellulaire/composition chimique , Protéines de Drosophila/métabolisme , Protéines de Drosophila/génétique , Protéines de Drosophila/composition chimiqueRÉSUMÉ
The ring-shaped Cohesin complex, consisting of core subunits Smc1, Smc3, Scc1, and SA2 (or its paralog SA1), topologically entraps two duplicated sister DNA molecules to establish sister chromatid cohesion in S-phase. It remains largely elusive how the Cohesin release factor Wapl binds the Cohesin complex, thereby inducing Cohesin disassociation from mitotic chromosomes to allow proper resolution and separation of sister chromatids. Here, we show that Wapl uses two structural modules containing the FGF motif and the YNARHWN motif, respectively, to simultaneously bind distinct pockets in the extensive composite interface between Scc1 and SA2. Strikingly, only when both docking modules are mutated, Wapl completely loses the ability to bind the Scc1-SA2 interface and release Cohesin, leading to erroneous chromosome segregation in mitosis. Surprisingly, Sororin, which contains a conserved FGF motif and functions as a master antagonist of Wapl in S-phase and G2-phase, does not bind the Scc1-SA2 interface. Moreover, Sgo1, the major protector of Cohesin at mitotic centromeres, can only compete with the FGF motif but not the YNARHWN motif of Wapl for binding Scc1-SA2 interface. Our data uncover the molecular mechanism by which Wapl binds Cohesin to ensure precise chromosome segregation.
Sujet(s)
Protéines du cycle cellulaire , Protéines chromosomiques nonhistones , Ségrégation des chromosomes , , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Protéines du cycle cellulaire/métabolisme , Protéines du cycle cellulaire/génétique , Humains , Liaison aux protéines , Protéines nucléaires/métabolisme , Protéines nucléaires/génétique , Motifs d'acides aminés , Mitose , Chromatides/métabolisme , Protéines de transport , Protéines proto-oncogènesRÉSUMÉ
Functional crosstalk between DNA methylation, histone H3 lysine-9 trimethylation (H3K9me3) and heterochromatin protein 1 (HP1) is essential for proper heterochromatin assembly and genome stability. However, how repressive chromatin cues guide DNA methyltransferases for region-specific DNA methylation remains largely unknown. Here, we report structure-function characterizations of DNA methyltransferase Defective-In-Methylation-2 (DIM2) in Neurospora. The DNA methylation activity of DIM2 requires the presence of both H3K9me3 and HP1. Our structural study reveals a bipartite DIM2-HP1 interaction, leading to a disorder-to-order transition of the DIM2 target-recognition domain that is essential for substrate binding. Furthermore, the structure of DIM2-HP1-H3K9me3-DNA complex reveals a substrate-binding mechanism distinct from that for its mammalian orthologue DNMT1. In addition, the dual recognition of H3K9me3 peptide by the DIM2 RFTS and BAH1 domains allosterically impacts the DIM2-substrate binding, thereby controlling DIM2-mediated DNA methylation. Together, this study uncovers how multiple heterochromatin factors coordinately orchestrate an activity-switching mechanism for region-specific DNA methylation.
Sujet(s)
Homologue-5 de la protéine chromobox , Protéines chromosomiques nonhistones , Méthylation de l'ADN , Protéines fongiques , Hétérochromatine , Histone , Hétérochromatine/métabolisme , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Histone/métabolisme , Histone/génétique , Protéines fongiques/métabolisme , Protéines fongiques/génétique , Liaison aux protéines , Neurospora crassa/génétique , Neurospora crassa/métabolismeSujet(s)
Tumeurs du cerveau , Protéines de liaison à l'ARN , Humains , Mâle , Femelle , Tumeurs du cerveau/anatomopathologie , Tumeurs du cerveau/métabolisme , Tumeurs du cerveau/génétique , Enfant d'âge préscolaire , Études rétrospectives , Protéines de liaison à l'ARN/métabolisme , Protéines de liaison à l'ARN/génétique , Protéine gliofibrillaire acide/métabolisme , Protéine gliofibrillaire acide/génétique , Nestine/métabolisme , Nestine/génétique , Lobe pariétal/anatomopathologie , Lobe pariétal/métabolisme , Protéines de tissu nerveux/métabolisme , Protéines de tissu nerveux/génétique , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Tumeurs du tronc cérébral/anatomopathologie , Tumeurs du tronc cérébral/génétique , Tumeurs du tronc cérébral/métabolisme , Tumeurs du tronc cérébral/chirurgie , Facteurs de transcription/métabolisme , Facteurs de transcription/génétique , Protéine SMARCB1/métabolisme , Protéine SMARCB1/génétique , Lobe frontal/anatomopathologie , Lobe frontal/métabolisme , Test des rosettes , Études de suivi , Antigène KI-67/métabolisme , Protéines de liaison à l'ADN/métabolisme , Protéines de liaison à l'ADN/génétiqueRÉSUMÉ
The localization of the meiotic specific regulatory molecule Moa1 to the centromere is regulated by the kinetochore protein CENP-C, and participates in the cohesion of sister chromatids in the centromere region mediated by the cohesin Rec8. To examine the interaction of these proteins, we analyzed the interactions between Moa1 and Rec8, CENP-C by yeast two-hybrid assays and identified several amino acid residues in Moa1 required for the interaction with CENP-C and Rec8. The results revealed that the interaction between Moa1 and CENP-C is crucial for the Moa1 to participate in the regulation of monopolar attachment of sister kinetochores. However, mutation at S143 and T150 of Moa1, which are required for interaction with Rec8 in the two-hybrid assay, did not show significant defects. Mutations in amino acid residues may not be sufficient to interfere with the interaction between Moa1 and Rec8 in vivo. Further research is needed to determine the interaction domain between Moa1 and Rec8. This study revealed specific amino acid sites at which Moa1 affects the meiotic homologous chromosome segregation, providing a deeper understanding of the mechanism of meiotic chromosome segregation.
Sujet(s)
Protéines chromosomiques nonhistones , Méiose , Protéines de Schizosaccharomyces pombe , Schizosaccharomyces , Schizosaccharomyces/génétique , Schizosaccharomyces/métabolisme , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Protéines de Schizosaccharomyces pombe/génétique , Protéines de Schizosaccharomyces pombe/métabolisme , Liaison aux protéines , Kinétochores/métabolisme , Protéines du cycle cellulaire/métabolisme , Protéines du cycle cellulaire/génétique , Techniques de double hybride , Ségrégation des chromosomes , , PhosphoprotéinesRÉSUMÉ
HP1 proteins are essential for establishing and maintaining transcriptionally silent heterochromatin. They dimerize, forming a binding interface to recruit diverse chromatin-associated factors. Although HP1 proteins are known to rapidly evolve, the extent of variation required to achieve functional specialization is unknown. To investigate how changes in amino acid sequence impacts heterochromatin formation, we performed a targeted mutagenesis screen of the S. pombe HP1 homolog, Swi6. Substitutions within an auxiliary surface adjacent to the HP1 dimerization interface produce Swi6 variants with divergent maintenance properties. Remarkably, substitutions at a single amino acid position lead to the persistent gain or loss of epigenetic inheritance. These substitutions increase Swi6 chromatin occupancy in vivo and altered Swi6-protein interactions that reprogram H3K9me maintenance. We show how relatively minor changes in Swi6 amino acid composition in an auxiliary surface can lead to profound changes in epigenetic inheritance providing a redundant mechanism to evolve HP1-effector specificity.
Sujet(s)
Protéines chromosomiques nonhistones , Épigenèse génétique , Hétérochromatine , Protéines de Schizosaccharomyces pombe , Schizosaccharomyces , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Protéines de Schizosaccharomyces pombe/métabolisme , Protéines de Schizosaccharomyces pombe/génétique , Schizosaccharomyces/métabolisme , Schizosaccharomyces/génétique , Hétérochromatine/métabolisme , Hétérochromatine/génétique , Homologue-5 de la protéine chromobox , Histone/métabolisme , Histone/génétique , Séquence d'acides aminés , Substitution d'acide aminé , Liaison aux protéines , Chromatine/métabolisme ,Sujet(s)
Centromère , Centromère/métabolisme , Protéines d'Arabidopsis/métabolisme , Protéines d'Arabidopsis/génétique , Arabidopsis/génétique , Arabidopsis/physiologie , Arabidopsis/croissance et développement , Arabidopsis/métabolisme , Développement embryonnaire , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétiqueRÉSUMÉ
Regulatory T (Treg) cells play a critical regulatory role in the immune system by suppressing excessive immune responses and maintaining immune balance. The effective migration of Treg cells is crucial for controlling the development and progression of inflammatory diseases. However, the mechanisms responsible for directing Treg cells into the inflammatory tissue remain incompletely elucidated. In this study, we identified BAF60b, a subunit of switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complexes, as a positive regulator of Treg cell migration that inhibits the progression of inflammation in experimental autoimmune encephalomyelitis (EAE) and colitis animal models. Mechanistically, transcriptome and genome-wide chromatin-landscaped analyses demonstrated that BAF60b interacts with the transcription factor RUNX1 to promote the expression of CCR9 on Treg cells, which in turn affects their ability to migrate to inflammatory tissues. Our work provides insights into the essential role of BAF60b in regulating Treg cell migration and its impact on inflammatory diseases.
Sujet(s)
Mouvement cellulaire , Inflammation , Souris de lignée C57BL , Lymphocytes T régulateurs , Lymphocytes T régulateurs/immunologie , Lymphocytes T régulateurs/métabolisme , Animaux , Souris , Inflammation/anatomopathologie , Inflammation/métabolisme , Assemblage et désassemblage de la chromatine , Protéines chromosomiques nonhistones/métabolisme , Encéphalomyélite auto-immune expérimentale/immunologie , Encéphalomyélite auto-immune expérimentale/anatomopathologie , Encéphalomyélite auto-immune expérimentale/métabolisme , Encéphalomyélite auto-immune expérimentale/génétique , Humains , Facteurs de transcription/métabolisme , Sous-unité alpha 2 du facteur CBF/métabolisme , Sous-unité alpha 2 du facteur CBF/génétique , Colite/métabolisme , Colite/anatomopathologie , Colite/immunologie , Colite/génétiqueRÉSUMÉ
DNA-loop extrusion is considered to be a universal principle of structural maintenance of chromosome (SMC) proteins with regard to chromosome organization. Despite recent advancements in structural dynamics studies that involve the use of cryogenic-electron microscopy (Cryo-EM), atomic force microscopy (AFM), etc., the precise molecular mechanism underlying DNA-loop extrusion by SMC proteins remains the subject of ongoing discussions. In this context, we propose a scrunching model that incorporates the anisotropic motion of SMC folding with a baton-pass mechanism, offering a potential explanation of how a "DNA baton" is transferred from the hinge domain to a DNA pocket via an anisotropic hinge motion. This proposed model provides insights into how SMC proteins unidirectionally extrude DNA loops in the direction of loop elongation while also maintaining the stability of a DNA loop throughout the dynamic process of DNA-loop extrusion.
Sujet(s)
ADN , ADN/composition chimique , ADN/génétique , Anisotropie , Protéines du cycle cellulaire/métabolisme , Protéines du cycle cellulaire/génétique , Protéines du cycle cellulaire/composition chimique , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/composition chimique , Protéines chromosomiques nonhistones/génétique , Conformation d'acide nucléique , Modèles moléculaires , Cryomicroscopie électronique , Microscopie à force atomiqueRÉSUMÉ
Meiotic cohesion loss underlies elevated rates of infertility and chromosome abnormalities in children of older women. A new study shows that cohesins are turned over throughout meiotic prophase, suggesting that cohesion loss is likely not solely due to early establishment of cohesion.
Sujet(s)
Protéines chromosomiques nonhistones , Ovocytes , Ovocytes/physiologie , Femelle , Humains , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , , Protéines du cycle cellulaire/métabolisme , Protéines du cycle cellulaire/génétique , Méiose , AnimauxRÉSUMÉ
The CRL4-DCAF15 E3 ubiquitin ligase complex is targeted by the aryl-sulfonamide molecular glues, leading to neo-substrate recruitment, ubiquitination, and proteasomal degradation. However, the physiological function of DCAF15 remains unknown. Using a domain-focused genetic screening approach, we reveal DCAF15 as an acute myeloid leukemia (AML)-biased dependency. Loss of DCAF15 results in suppression of AML through compromised replication fork integrity and consequent accumulation of DNA damage. Accordingly, DCAF15 loss sensitizes AML to replication stress-inducing therapeutics. Mechanistically, we discover that DCAF15 directly interacts with the SMC1A protein of the cohesin complex and destabilizes the cohesin regulatory factors PDS5A and CDCA5. Loss of PDS5A and CDCA5 removal precludes cohesin acetylation on chromatin, resulting in uncontrolled chromatin loop extrusion, defective DNA replication, and apoptosis. Collectively, our findings uncover an endogenous, cell autonomous function of DCAF15 in sustaining AML proliferation through post-translational control of cohesin dynamics.
Sujet(s)
Protéines du cycle cellulaire , Protéines chromosomiques nonhistones , , Altération de l'ADN , Réplication de l'ADN , Leucémie aigüe myéloïde , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Humains , Protéines du cycle cellulaire/métabolisme , Protéines du cycle cellulaire/génétique , Leucémie aigüe myéloïde/métabolisme , Leucémie aigüe myéloïde/génétique , Leucémie aigüe myéloïde/anatomopathologie , Lignée cellulaire tumorale , Acétylation , Animaux , Protéines nucléaires/métabolisme , Protéines nucléaires/génétique , Souris , Chromatine/métabolisme , Ubiquitin-protein ligases/métabolisme , Ubiquitin-protein ligases/génétique , Apoptose , Prolifération cellulaire , Cellules HEK293RÉSUMÉ
Retrotransposon control in mammals is an intricate process that is effectuated by a broad network of chromatin regulatory pathways. We previously discovered ChAHP, a protein complex with repressive activity against short interspersed element (SINE) retrotransposons that is composed of the transcription factor ADNP, chromatin remodeler CHD4, and HP1 proteins. Here we identify ChAHP2, a protein complex homologous to ChAHP, in which ADNP is replaced by ADNP2. ChAHP2 is predominantly targeted to endogenous retroviruses (ERVs) and long interspersed elements (LINEs) via HP1ß-mediated binding of H3K9 trimethylated histones. We further demonstrate that ChAHP also binds these elements in a manner mechanistically equivalent to that of ChAHP2 and distinct from DNA sequence-specific recruitment at SINEs. Genetic ablation of ADNP2 alleviates ERV and LINE1 repression, which is synthetically exacerbated by additional depletion of ADNP. Together, our results reveal that the ChAHP and ChAHP2 complexes function to control both nonautonomous and autonomous retrotransposons by complementary activities, further adding to the complexity of mammalian transposon control.
Sujet(s)
Rétroéléments , Animaux , Humains , Souris , Homologue-5 de la protéine chromobox , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Rétrovirus endogènes/génétique , Régulation de l'expression des gènes/génétique , Histone/métabolisme , Histone/génétique , Éléments LINE/génétique , Liaison aux protéines , Rétroéléments/génétique , Facteurs de transcription/métabolisme , Facteurs de transcription/génétique , Complexes multiprotéiques/métabolismeRÉSUMÉ
Centromeres are specialized chromosomal domains where the kinetochores assemble during cell division to ensure accurate transmission of the genetic information to the two daughter cells. The centromeric function is evolutionary conserved and, in most organisms, centromeres are epigenetically defined by a unique chromatin containing the histone H3 variant CENP-A. The canonical regulators of CENP-A assembly and maintenance are well-known, yet some of the molecular mechanisms regulating this complex process have only recently been unveiled. We review the most recent advances on the topic, including the emergence of new and unexpected factors that favor and regulate CENP-A assembly and/or maintenance.
Sujet(s)
Protéine A du centromère , Centromère , Protéines chromosomiques nonhistones , Centromère/métabolisme , Humains , Animaux , Protéine A du centromère/métabolisme , Protéines chromosomiques nonhistones/métabolisme , Autoantigènes/métabolisme , Histone/métabolisme , Chromatine/métabolisme , Kinétochores/métabolismeRÉSUMÉ
Glycine- and arginine-rich (GAR) motifs, commonly found in RNA-binding and -processing proteins, can be symmetrically (SDMA) or asymmetrically (ADMA) dimethylated at the arginine residue by protein arginine methyltransferases. Arginine-methylated protein motifs are usually read by Tudor domain-containing proteins. Here, using a GFP-Trap, we identify a non-Tudor domain protein, squamous cell carcinoma antigen recognized by T cells 3 (SART3), as a reader for SDMA-marked GAR motifs. Structural analysis and mutagenesis of SART3 show that aromatic residues lining a groove between two adjacent aromatic-rich half-a-tetratricopeptide (HAT) repeat domains are essential for SART3 to recognize and bind to SDMA-marked GAR motif peptides, as well as for the interaction between SART3 and the GAR-motif-containing proteins fibrillarin and coilin. Further, we show that the loss of this reader ability affects RNA splicing. Overall, our findings broaden the range of potential SDMA readers to include HAT domains.
Sujet(s)
Motifs d'acides aminés , Arginine , Glycine , Arginine/métabolisme , Arginine/composition chimique , Humains , Glycine/métabolisme , Glycine/composition chimique , Protéines de liaison à l'ARN/métabolisme , Protéines de liaison à l'ARN/composition chimique , Protéines de liaison à l'ARN/génétique , Liaison aux protéines , Épissage des ARN , Cellules HEK293 , Méthylation , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/composition chimique , Protein-arginine N-methyltransferases/métabolisme , Protein-arginine N-methyltransferases/composition chimiqueRÉSUMÉ
The function of glioma stem cells (GSCs) is closely related to the progression of glioblastoma multiforme (GBM). Centromere protein A (CENPA) has been confirmed to be related to the poor prognosis of GBM patients. However, whether CENPA regulates GSCs function to mediate GBM progression is still unclear. GSCs were isolated from GBM cells. The expression of CENPA and guanylate-binding protein 2 (GBP2) was examined by quantitative real-time PCR and western blot. GSCs proliferation and stemness were assessed using EdU assay and sphere formation assay. Cell ferroptosis was evaluated by detecting related factors. The interaction between CENPA and GBP2 was analyzed by ChIP assay and dual-luciferase reporter assay. Animal experiments were conducted to measure the effect of CENPA knockdown on the tumorigenicity of GSCs in vivo. CENPA was upregulated in GBM tissues and GSCs. CENPA knockdown inhibited GSCs proliferation, stemnness, and promoted ferroptosis. GBP2 was overexpressed in GBM tissues and GSCs, and CENPA enhanced GBP2 transcription by binding to its promoter region. CENPA overexpression accelerated GSCs proliferation and stemnness and suppressed ferroptosis, while GBP2 knockdown reversed these effects. Downregulation of CENPA reduced the tumorigenicity of GSCs by decreasing GBP2 expression in vivo. In conclusion, CENPA enhanced GBP2 transcription to increase its expression, thus accelerating GSCs proliferation and stemnness and repressing ferroptosis. Our findings promote a new idea for GBM treatment.
Sujet(s)
Tumeurs du cerveau , Ferroptose , Glioblastome , Cellules souches tumorales , Ferroptose/génétique , Ferroptose/physiologie , Humains , Glioblastome/anatomopathologie , Glioblastome/génétique , Glioblastome/métabolisme , Cellules souches tumorales/anatomopathologie , Cellules souches tumorales/métabolisme , Tumeurs du cerveau/anatomopathologie , Tumeurs du cerveau/génétique , Tumeurs du cerveau/métabolisme , Animaux , Protéines G/métabolisme , Protéines G/génétique , Évolution de la maladie , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Régulation de l'expression des gènes tumoraux/génétique , Souris , Prolifération cellulaire/génétique , Lignée cellulaire tumorale , Souris nudeRÉSUMÉ
The contrast between the disruption of genome topology after cohesin loss and the lack of downstream gene expression changes instigates intense debates regarding the structure-function relationship between genome and gene regulation. Here, by analyzing transcriptome and chromatin accessibility at the single-cell level, we discover that, instead of dictating population-wide gene expression levels, cohesin supplies a general function to neutralize stochastic coexpression tendencies of cis-linked genes in single cells. Notably, cohesin loss induces widespread gene coactivation and chromatin co-opening tens of million bases apart in cis. Spatial genome and protein imaging reveals that cohesin prevents gene co-bursting along the chromosome and blocks spatial mixing of transcriptional hubs. Single-molecule imaging shows that cohesin confines the exploration of diverse enhancer and core promoter binding transcriptional regulators. Together, these results support that cohesin arranges nuclear topology to control gene coexpression in single cells.
Sujet(s)
Protéines du cycle cellulaire , Chromatine , Protéines chromosomiques nonhistones , , Protéines du cycle cellulaire/métabolisme , Protéines du cycle cellulaire/génétique , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Chromatine/métabolisme , Chromatine/génétique , Régulation de l'expression des gènes , Régions promotrices (génétique) , Analyse sur cellule unique , Saccharomyces cerevisiae/génétique , Saccharomyces cerevisiae/métabolisme , TranscriptomeRÉSUMÉ
Small cell lung cancers (SCLCs) are composed of heterogeneous subtypes marked by lineage-specific transcription factors, including ASCL1, NEUROD1, and POU2F3. POU2F3-positive SCLCs, â¼12% of all cases, are uniquely dependent on POU2F3 itself; as such, approaches to attenuate POU2F3 expression may represent new therapeutic opportunities. Here using genome-scale screens for regulators of POU2F3 expression and SCLC proliferation, we define mSWI/SNF complexes as top dependencies specific to POU2F3-positive SCLC. Notably, chemical disruption of mSWI/SNF ATPase activity attenuates proliferation of all POU2F3-positive SCLCs, while disruption of non-canonical BAF (ncBAF) via BRD9 degradation is effective in pure non-neuroendocrine POU2F3-SCLCs. mSWI/SNF targets to and maintains accessibility over gene loci central to POU2F3-mediated gene regulatory networks. Finally, clinical-grade pharmacologic disruption of SMARCA4/2 ATPases and BRD9 decreases POU2F3-SCLC tumor growth and increases survival in vivo. These results demonstrate mSWI/SNF-mediated governance of the POU2F3 oncogenic program and suggest mSWI/SNF inhibition as a therapeutic strategy for POU2F3-positive SCLCs.
Sujet(s)
Régulation de l'expression des gènes tumoraux , Tumeurs du poumon , Carcinome pulmonaire à petites cellules , Facteurs de transcription , Humains , Carcinome pulmonaire à petites cellules/génétique , Carcinome pulmonaire à petites cellules/métabolisme , Carcinome pulmonaire à petites cellules/anatomopathologie , Carcinome pulmonaire à petites cellules/traitement médicamenteux , Tumeurs du poumon/génétique , Tumeurs du poumon/métabolisme , Tumeurs du poumon/anatomopathologie , Tumeurs du poumon/traitement médicamenteux , Animaux , Facteurs de transcription/métabolisme , Facteurs de transcription/génétique , Souris , Lignée cellulaire tumorale , Prolifération cellulaire , Protéines chromosomiques nonhistones/métabolisme , Protéines chromosomiques nonhistones/génétique , Facteur de transcription Oct-3/métabolisme , Facteur de transcription Oct-3/génétiqueRÉSUMÉ
A set of arylazopyrazole-based inhibitors targeting the mitotic motor protein CENP-E was discovered through the chemical platform using the quantitative cyclization of 1,3-diketone intermediate with various hydrazines under mild conditions. Through this efficient platform, the structure-activity relationship pertaining to the pyrazole photoswitch in photoswitchable CENP-E inhibitors not only in vitro but also in cells was successfully clarified.
Sujet(s)
Protéines chromosomiques nonhistones , Pyrazoles , Cyclisation , Pyrazoles/composition chimique , Pyrazoles/pharmacologie , Pyrazoles/synthèse chimique , Relation structure-activité , Humains , Protéines chromosomiques nonhistones/antagonistes et inhibiteurs , Protéines chromosomiques nonhistones/métabolisme , Structure moléculaire , Composés azoïques/composition chimique , Composés azoïques/pharmacologie , Composés azoïques/synthèse chimique , Relation dose-effet des médicamentsRÉSUMÉ
Centromeres are specific segments of chromosomes comprising two types of nucleosomes: canonical nucleosomes containing an octamer of H2A, H2B, H3, and H4 histones and CENP-A nucleosomes in which H3 is replaced with its analogue CENP-A. This modification leads to a difference in DNA wrapping (â¼121 bp), considerably less than 147 bp in canonical nucleosomes. We used atomic force microscopy (AFM) and high-speed AFM (HS-AFM) to characterize nanoscale features and dynamics for both types of nucleosomes. For both nucleosomes, spontaneous asymmetric unwrapping of DNA was observed, and this process occurs via a transient state with â¼100 bp DNA wrapped around the core, followed by a rapid dissociation of DNA. Additionally, HS-AFM revealed higher stability of CENP-A nucleosomes compared with H3 nucleosomes in which dissociation of the histone core occurs prior to the nucleosome dissociation. These results help elucidate the differences between these nucleosomes and the potential biological necessity for CENP-A nucleosomes.
Sujet(s)
Centromère , ADN , Histone , Microscopie à force atomique , Nucléosomes , Nucléosomes/composition chimique , Nucléosomes/métabolisme , Microscopie à force atomique/méthodes , Centromère/métabolisme , Centromère/composition chimique , Histone/composition chimique , Histone/métabolisme , ADN/composition chimique , ADN/métabolisme , Protéine A du centromère/composition chimique , Protéine A du centromère/métabolisme , Protéines chromosomiques nonhistones/composition chimique , Protéines chromosomiques nonhistones/métabolisme , Humains , AnimauxRÉSUMÉ
Cohesin, a chromatin-associated protein complex with four core subunits (Smc1a, Smc3, Rad21 and either Stag1 or 2), has a central role in cell proliferation and gene expression in metazoans. Human developmental disorders termed 'cohesinopathies' are characterized by germline variants of cohesin or its regulators that do not entirely eliminate cohesin function. However, it is not clear whether mutations in individual cohesin subunits have independent developmental consequences. Here, we show that zebrafish rad21 or stag2b mutants independently influence embryonic tailbud development. Both mutants have altered mesoderm induction, but only homozygous or heterozygous rad21 mutation affects cell cycle gene expression. stag2b mutants have narrower notochords and reduced Wnt signaling in neuromesodermal progenitors as revealed by single-cell RNA sequencing. Stimulation of Wnt signaling rescues transcription and morphology in stag2b, but not rad21, mutants. Our results suggest that mutations altering the quantity versus composition of cohesin have independent developmental consequences, with implications for the understanding and management of cohesinopathies.