RESUMEN
Protein-protein interactions (PPIs) stabilization with molecular glues plays a crucial role in drug discovery, albeit with significant challenges. In this study, we propose a dual-site approach, targeting the PPI region and its dynamic surroundings. We conduct molecular dynamics simulations to identify critical sites on the PPI that stabilize the cyclin-dependent kinase 12 - DNA damage-binding protein 1 (CDK12-DDB1) complex, resulting in further cyclin K degradation. This exploration leads to the creation of LL-K12-18, a dual-site molecular glue, which enhances the glue properties to augment degradation kinetics and efficiency. Notably, LL-K12-18 demonstrates strong inhibition of gene transcription and anti-proliferative effects in tumor cells, showing significant potency improvements in MDA-MB-231 (88-fold) and MDA-MB-468 cells (307-fold) when compared to its precursor compound SR-4835. These findings underscore the potential of dual-site approaches in disrupting CDK12 function and offer a structural insight-based framework for the design of cyclin K molecular glues.
Asunto(s)
Quinasas Ciclina-Dependientes , Unión Proteica , Humanos , Línea Celular Tumoral , Proliferación Celular , Quinasas Ciclina-Dependientes/metabolismo , Ciclinas , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/química , Simulación de Dinámica MolecularRESUMEN
Ubiquitination is a crucial posttranslational modification required for the proper repair of DNA double-strand breaks (DSBs) induced by ionizing radiation (IR). DSBs are mainly repaired through homologous recombination (HR) when template DNA is present and nonhomologous end joining (NHEJ) in its absence. In addition, microhomology-mediated end joining (MMEJ) and single-strand annealing (SSA) provide backup DSBs repair pathways. However, the mechanisms controlling their use remain poorly understood. By using a high-resolution CRISPR screen of the ubiquitin system after IR, we systematically uncover genes required for cell survival and elucidate a critical role of the E3 ubiquitin ligase SCFcyclin F in cell cycle-dependent DSB repair. We show that SCFcyclin F-mediated EXO1 degradation prevents DNA end resection in mitosis, allowing MMEJ to take place. Moreover, we identify a conserved cyclin F recognition motif, distinct from the one used by other cyclins, with broad implications in cyclin specificity for cell cycle control.
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Ciclo Celular , Ciclinas , Roturas del ADN de Doble Cadena , Reparación del ADN , Exodesoxirribonucleasas , Humanos , Ciclo Celular/genética , Exodesoxirribonucleasas/metabolismo , Exodesoxirribonucleasas/genética , Ciclinas/metabolismo , Ciclinas/genética , Enzimas Reparadoras del ADN/metabolismo , Enzimas Reparadoras del ADN/genética , Reparación del ADN por Unión de Extremidades , Ubiquitinación , Radiación IonizanteRESUMEN
KEY MESSAGE: BIG regulates ground tissue formative divisions by bridging the auxin gradient with SHR abundance in Arabidopsis roots. The formative divisions of cortex/endodermis initials (CEIs) and CEI daughter cells (CEIDs) in Arabidopsis roots are coordinately controlled by the longitudinal auxin gradient and the radial SHORT ROOT (SHR) abundance. However, the mechanism underlying this coordination remains poorly understood. In this study, we demonstrate that BIG regulates ground tissue formative divisions by bridging the auxin gradient with SHR abundance. Mutations in BIG gene repressed cell cycle progression, delaying the formative divisions within the ground tissues and impairing the establishment of endodermal and cortical identities. In addition, we uncovered auxin's suppressive effect on BIG expression, triggering CYCLIND6;1 (CYCD6;1) activation in an SHR-dependent fashion. Moreover, the degradation of RETINOBLASTOMA-RELATED (RBR) is jointly regulated by BIG and CYCD6;1. The loss of BIG function led to RBR protein accumulation, detrimentally impacting the SHR/SCARECROW (SCR) protein complex and the CEI/CEID formative divisions. Collectively, these findings shed light on a fundamental mechanism wherein BIG intricately coordinates the interplay between SHR/SCR and auxin, steering ground tissue patterning within Arabidopsis root tissue.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Regulación de la Expresión Génica de las Plantas , Ácidos Indolacéticos , Raíces de Plantas , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/citología , Ácidos Indolacéticos/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Raíces de Plantas/citología , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Raíces de Plantas/genética , División Celular Asimétrica , Mutación/genética , Células Madre/metabolismo , Células Madre/citología , Ciclinas/metabolismo , Ciclinas/genética , Proteínas de Unión a Calmodulina , Factores de TranscripciónRESUMEN
MAIN CONCLUSION: We studied the D3-type cyclin function during gynoecium development in Arabidopsis and how they are related to the hormone cytokinin and the transcription factor SPATULA. Growth throughout the life of plants is sustained by cell division and differentiation processes in meristematic tissues. In Arabidopsis, gynoecium development implies a multiphasic process where the tissues required for pollination, fertilization, and seed development form. The Carpel Margin Meristem (CMM) is a mass of undifferentiated cells that gives rise to the gynoecium internal tissues, such as septum, ovules, placenta, funiculus, transmitting tract, style, and stigma. Different genetic and hormonal factors, including cytokinin, control the CMM function. Cytokinin regulates the cell cycle transitions through the activation of cell cycle regulators as cyclin genes. D3-type cyclins are expressed in proliferative tissues, favoring the mitotic cell cycle over the endoreduplication. Though the role of cytokinin in CMM and gynoecium development is highly studied, its specific role in regulating the cell cycle in this tissue remains unclear. Additionally, despite extensive research on the relationship between CYCD3 genes and cytokinin, the regulatory mechanism that connects them remains elusive. Here, we found that D3-type cyclins are expressed in proliferative medial and lateral tissues. Conversely, the depletion of the three CYCD3 genes showed that they are not essential for gynoecium development. However, the addition of exogenous cytokinin showed that they could control the division/differentiation balance in gynoecium internal tissues and outgrowths. Finally, we found that SPATULA can be a mechanistic link between cytokinin and the D3-type cyclins. The data suggest that the role of D3-type cyclins in gynoecium development is related to the cytokinin response, and they might be activated by the transcription factor SPATULA.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Citocininas , Flores , Regulación de la Expresión Génica de las Plantas , Citocininas/metabolismo , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Flores/crecimiento & desarrollo , Flores/genética , Flores/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Ciclina D3/metabolismo , Ciclina D3/genética , Meristema/genética , Meristema/crecimiento & desarrollo , Meristema/metabolismo , CiclinasRESUMEN
Regulated cell cycle progression ensures homeostasis and prevents cancer. In proliferating cells, premature S phase entry is avoided by the E3 ubiquitin ligase anaphasepromoting complex/cyclosome (APC/C), although the APC/C substrates whose degradation restrains G1-S progression are not fully known. The APC/C is also active in arrested cells that exited the cell cycle, but it is not clear whether APC/C maintains all types of arrest. Here, by expressing the APC/C inhibitor, EMI1, we show that APC/C activity is essential to prevent S phase entry in cells arrested by pharmacological cyclin-dependent kinases 4 and 6 (CDK4/6) inhibition (Palbociclib). Thus, active protein degradation is required for arrest alongside repressed cell cycle gene expression. The mechanism of rapid and robust arrest bypass from inhibiting APC/C involves CDKs acting in an atypical order to inactivate retinoblastoma-mediated E2F repression. Inactivating APC/C first causes mitotic cyclin B accumulation which then promotes cyclin A expression. We propose that cyclin A is the key substrate for maintaining arrest because APC/C-resistant cyclin A, but not cyclin B, is sufficient to induce S phase entry. Cells bypassing arrest from CDK4/6 inhibition initiate DNA replication with severely reduced origin licensing. The simultaneous accumulation of S phase licensing inhibitors, such as cyclin A and geminin, with G1 licensing activators disrupts the normal order of G1-S progression. As a result, DNA synthesis and cell proliferation are profoundly impaired. Our findings predict that cancers with elevated EMI1 expression will tend to escape CDK4/6 inhibition into a premature, underlicensed S phase and suffer enhanced genome instability.
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Quinasa 4 Dependiente de la Ciclina , Quinasa 6 Dependiente de la Ciclina , Humanos , Quinasa 6 Dependiente de la Ciclina/metabolismo , Quinasa 6 Dependiente de la Ciclina/genética , Quinasa 4 Dependiente de la Ciclina/metabolismo , Quinasa 4 Dependiente de la Ciclina/genética , Quinasa 4 Dependiente de la Ciclina/antagonistas & inhibidores , Ciclosoma-Complejo Promotor de la Anafase/metabolismo , Ciclosoma-Complejo Promotor de la Anafase/genética , Línea Celular Tumoral , Fase S/efectos de los fármacos , Piridinas/farmacología , Piperazinas/farmacología , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Factores de Transcripción E2F/metabolismo , Factores de Transcripción E2F/genética , Puntos de Control del Ciclo Celular/efectos de los fármacos , Ciclinas/metabolismo , Ciclinas/genética , Proteínas F-BoxRESUMEN
Acute kidney injury (AKI) strongly upregulates the transcription factor Foxm1 in the proximal tubule in vivo, and Foxm1 drives epithelial proliferation in vitro. Here, we report that deletion of Foxm1 either with a nephron-specific Cre driver or by inducible global deletion reduced proximal tubule proliferation after ischemic injury in vivo. Foxm1 deletion led to increased AKI to chronic kidney disease transition, with enhanced fibrosis and ongoing tubule injury 6 weeks after injury. We report ERK mediated FOXM1 induction downstream of the EGFR in primary proximal tubule cells. We defined FOXM1 genomic binding sites by cleavage under targets and release using nuclease (CUT&RUN) and compared the genes located near FOXM1 binding sites with genes downregulated in primary proximal tubule cells after FOXM1 knockdown. The aligned data sets revealed the cell cycle regulator cyclin F (CCNF) as a putative FOXM1 target. We identified 2 cis regulatory elements that bound FOXM1 and regulated CCNF expression, demonstrating that Ccnf is strongly induced after kidney injury and that Foxm1 deletion abrogates Ccnf expression in vivo and in vitro. Knockdown of CCNF also reduced proximal tubule proliferation in vitro. These studies identify an ERK/FOXM1/CCNF signaling pathway that regulates injury-induced proximal tubule cell proliferation.
Asunto(s)
Lesión Renal Aguda , Proliferación Celular , Células Epiteliales , Proteína Forkhead Box M1 , Túbulos Renales Proximales , Animales , Proteína Forkhead Box M1/metabolismo , Proteína Forkhead Box M1/genética , Ratones , Proliferación Celular/genética , Lesión Renal Aguda/metabolismo , Lesión Renal Aguda/patología , Lesión Renal Aguda/genética , Túbulos Renales Proximales/metabolismo , Túbulos Renales Proximales/patología , Túbulos Renales Proximales/citología , Células Epiteliales/metabolismo , Células Epiteliales/patología , Masculino , Ciclinas/metabolismo , Ciclinas/genética , Ratones Noqueados , Modelos Animales de Enfermedad , Regulación de la Expresión GénicaRESUMEN
Protein synthesis is metabolically costly and must be tightly coordinated with changing cellular needs and nutrient availability. The cap-binding protein eIF4E makes the earliest contact between mRNAs and the translation machinery, offering a key regulatory nexus. We acutely depleted this essential protein and found surprisingly modest effects on cell growth and recovery of protein synthesis. Paradoxically, impaired protein biosynthesis upregulated genes involved in the catabolism of aromatic amino acids simultaneously with the induction of the amino acid biosynthetic regulon driven by the integrated stress response factor GCN4. We further identified the translational control of Pho85 cyclin 5 (PCL5), a negative regulator of Gcn4, that provides a consistent protein-to-mRNA ratio under varied translation environments. This regulation depended in part on a uniquely long poly(A) tract in the PCL5 5' UTR and poly(A) binding protein. Collectively, these results highlight how eIF4E connects protein synthesis to metabolic gene regulation, uncovering mechanisms controlling translation during environmental challenges.
Asunto(s)
Aminoácidos , Factor 4E Eucariótico de Iniciación , Regulación Fúngica de la Expresión Génica , Biosíntesis de Proteínas , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Factor 4E Eucariótico de Iniciación/metabolismo , Factor 4E Eucariótico de Iniciación/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Aminoácidos/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , ARN Mensajero/metabolismo , ARN Mensajero/genética , Regiones no Traducidas 5' , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Ciclinas/genética , Ciclinas/metabolismo , Proteínas de Unión a Poli(A)/metabolismo , Proteínas de Unión a Poli(A)/genéticaRESUMEN
The study of the physiological and pathophysiological processes under extreme conditions facilitates a better understanding of the state of a healthy organism and can also shed light on the pathogenesis of diseases. In recent years, it has become evident that gravitational stress affects both the whole organism and individual cells. We have previously demonstrated that simulated microgravity inhibits proliferation, induces apoptosis, changes morphology, and alters the surface marker expression of megakaryoblast cell line MEG-01. In the present work, we investigate the expression of cell cycle cyclins in MEG-01 cells. We performed several experiments for 24 h, 72 h, 96 h and 168 h. Flow cytometry and Western blot analysis demonstrated that the main change in the levels of cyclins expression occurs under conditions of simulated microgravity after 96 h. Thus, the level of cyclin A expression showed an increase in the RPM group during the first 4 days, followed by a decrease, which, together with the peak of cyclin D, may indicate inhibition of the cell cycle in the G2 phase, before mitosis. In addition, based on the data obtained by PCR analysis, we were also able to see that both cyclin A and cyclin B expression showed a peak at 72 h, followed by a gradual decrease at 96 h. STED microscopy data also confirmed that the main change in cyclin expression of MEG-01 cells occurs at 96 h, under simulated microgravity conditions, compared to static control. These results suggested that the cell cycle disruption induced by RPM-simulated microgravity in MEG-01 cells may be associated with the altered expression of the main regulators of the cell cycle. Thus, these data implicate the development of cellular stress in MEG-01 cells, which may be important for proliferating human cells exposed to microgravity in real space.
Asunto(s)
Ciclo Celular , Ciclinas , Simulación de Ingravidez , Humanos , Línea Celular , Ciclinas/metabolismo , Ciclinas/genética , Células Progenitoras de Megacariocitos/metabolismo , Células Progenitoras de Megacariocitos/citología , Ciclina A/metabolismo , Ciclina A/genética , Proliferación Celular , Ciclina B/metabolismo , Ciclina B/genéticaRESUMEN
Protein synthesis underpins cell growth and controls when cells commit to a new round of cell division at a point in late G1 of the cell cycle called Start. Passage through Start also coincides with the duplication of the microtubule-organizing centers, the yeast spindle pole bodies, which will form the 2 poles of the mitotic spindle that segregates the chromosomes in mitosis. The conserved Mps1p kinase governs the duplication of the spindle pole body (SPB) in Saccharomyces cerevisiae. Here, we show that the MPS1 transcript has a short upstream open reading frame (uORF) that represses the synthesis of Mps1p. Mutating the MPS1 uORF makes the cells smaller, accelerates the appearance of Mps1p in late G1, and promotes completion of Start. Monitoring the SPB in the cell cycle using structured illumination microscopy revealed that mutating the MPS1 uORF enabled cells to duplicate their SPB earlier at a smaller cell size. The accelerated Start of MPS1 uORF mutants depends on the G1 cyclin Cln3p and the transcriptional repressor Whi5p but not on the Cln1,2p G1 cyclins. These results identify growth inputs in mechanisms that control duplication of the microtubule-organizing center and implicate these processes in the coupling of cell growth with division.
Asunto(s)
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Cuerpos Polares del Huso , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Cuerpos Polares del Huso/metabolismo , Cuerpos Polares del Huso/genética , Ciclinas/metabolismo , Ciclinas/genética , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Sistemas de Lectura Abierta , Biosíntesis de Proteínas , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , División Celular/genética , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Regulación Fúngica de la Expresión GénicaRESUMEN
OBJECTIVE: The F-box protein (FBXO) family plays a key role in the malignant progression of tumors. However, the biological functions and clinical value of the FBXO family in liver cancer remain unclear. Our study comprehensively assessed the clinical value of the FBXO family in hepatocellular carcinoma (HCC) and constructed a novel signature based on the FBXO family to predict prognosis and guide precision immunotherapy. METHODS: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) databases were utilized to investigate the expression characteristics and prognostic value of the FBXO family in HCC. A predictive model based on the FBXO family using TCGA database; and its predictive ability was validated using the ICGC database. Further analyses revealed that this predictive model can independently predict the overall survival (OS) rate of patients with HCC. We further analyzed the association of this predictive model with signaling pathways, clinical pathological features, somatic mutations, and immune therapy responses. Finally, we validated the biological functions of cyclin F (CCNF) through in vitro experiments. RESULTS: A predictive model involving three genes (CCNF, FBXO43, and FBXO45) was constructed, effectively identifying high and low-risk patients with differences in OS, clinicopathological characteristics, somatic mutations, and immune cell infiltration status. Additionally, knock-down of CCNF in HCC cell lines reduced cell proliferation in vitro, suggesting that CCNF may be a potential therapeutic target for HCC. CONCLUSIONS: The predictive model based on the FBXO family can effectively predict OS and the immune therapy response in HCC. Additionally, CCNF is a potential therapeutic target for HCC.
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Carcinoma Hepatocelular , Proteínas F-Box , Neoplasias Hepáticas , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patología , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patología , Proteínas F-Box/genética , Proteínas F-Box/metabolismo , Pronóstico , Masculino , Femenino , Línea Celular Tumoral , Persona de Mediana Edad , Regulación Neoplásica de la Expresión Génica , Ciclinas/genética , Ciclinas/metabolismo , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Proliferación Celular/genética , Bases de Datos GenéticasRESUMEN
The canonical mitotic cell cycle coordinates DNA replication, centriole duplication and cytokinesis to generate two cells from one1. Some cells, such as mammalian trophoblast giant cells, use cell cycle variants like the endocycle to bypass mitosis2. Differentiating multiciliated cells, found in the mammalian airway, brain ventricles and reproductive tract, are post-mitotic but generate hundreds of centrioles, each of which matures into a basal body and nucleates a motile cilium3,4. Several cell cycle regulators have previously been implicated in specific steps of multiciliated cell differentiation5,6. Here we show that differentiating multiciliated cells integrate cell cycle regulators into a new alternative cell cycle, which we refer to as the multiciliation cycle. The multiciliation cycle redeploys many canonical cell cycle regulators, including cyclin-dependent kinases (CDKs) and their cognate cyclins. For example, cyclin D1, CDK4 and CDK6, which are regulators of mitotic G1-to-S progression, are required to initiate multiciliated cell differentiation. The multiciliation cycle amplifies some aspects of the canonical cell cycle, such as centriole synthesis, and blocks others, such as DNA replication. E2F7, a transcriptional regulator of canonical S-to-G2 progression, is expressed at high levels during the multiciliation cycle. In the multiciliation cycle, E2F7 directly dampens the expression of genes encoding DNA replication machinery and terminates the S phase-like gene expression program. Loss of E2F7 causes aberrant acquisition of DNA synthesis in multiciliated cells and dysregulation of multiciliation cycle progression, which disrupts centriole maturation and ciliogenesis. We conclude that multiciliated cells use an alternative cell cycle that orchestrates differentiation instead of controlling proliferation.
Asunto(s)
Ciclo Celular , Diferenciación Celular , Cilios , Animales , Femenino , Masculino , Ratones , Ciclo Celular/genética , Centriolos/metabolismo , Cilios/metabolismo , Quinasas Ciclina-Dependientes/metabolismo , Ciclinas/metabolismo , Replicación del ADN/genética , Factor de Transcripción E2F7/metabolismo , Ratones Endogámicos C57BL , MitosisRESUMEN
Progression through the cell cycle depends on the phosphorylation of key substrates by cyclin-dependent kinases. In budding yeast, these substrates include the transcriptional inhibitor Whi5 that regulates G1/S transition. In early G1 phase, Whi5 is hypo-phosphorylated and inhibits the Swi4/Swi6 (SBF) complex that promotes transcription of the cyclins CLN1 and CLN2. In late G1, Whi5 is rapidly hyper-phosphorylated by Cln1 and Cln2 in complex with the cyclin-dependent kinase Cdk1. This hyper-phosphorylation inactivates Whi5 and excludes it from the nucleus. Here, we set out to determine the molecular mechanisms responsible for Whi5's multi-site phosphorylation and how they regulate the cell cycle. To do this, we first identified the 19 Whi5 sites that are appreciably phosphorylated and then determined which of these sites are responsible for G1 hypo-phosphorylation. Mutation of 7 sites removed G1 hypo-phosphorylation, increased cell size, and delayed the G1/S transition. Moreover, the rapidity of Whi5 hyper-phosphorylation in late G1 depends on "priming" sites that dock the Cks1 subunit of Cln1,2-Cdk1 complexes. Hyper-phosphorylation is crucial for Whi5 nuclear export, normal cell size, full expression of SBF target genes, and timely progression through both the G1/S transition and S/G2/M phases. Thus, our work shows how Whi5 phosphorylation regulates the G1/S transition and how it is required for timely progression through S/G2/M phases and not only G1 as previously thought.
Asunto(s)
Ciclo Celular , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Fosforilación , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Ciclinas/metabolismo , Ciclinas/genética , Proteínas Represoras/metabolismo , Proteínas Represoras/genéticaRESUMEN
A versatile division of apicomplexan parasites and a dearth of conserved regulators have hindered the progress of apicomplexan cell cycle studies. While most apicomplexans divide in a multinuclear fashion, Toxoplasma gondii tachyzoites divide in the traditional binary mode. We previously identified five Toxoplasma CDK-related kinases (Crk). Here, we investigated TgCrk4 and its cyclin partner TgCyc4. We demonstrated that TgCrk4 regulates conventional G2 phase processes, such as repression of chromosome rereplication and centrosome reduplication, and acts upstream of the spindle assembly checkpoint. The spatial TgCyc4 dynamics supported the TgCrk4-TgCyc4 complex role in the coordination of chromosome and centrosome cycles. We also identified a dominant TgCrk4-TgCyc4 complex interactor, TgiRD1 protein, related to DNA replication licensing factor CDT1 but played no role in licensing DNA replication in the G1 phase. Our results showed that TgiRD1 also plays a role in controlling chromosome and centrosome reduplication. Global phosphoproteome analyses identified TgCrk4 substrates, including TgORC4, TgCdc20, TgGCP2, and TgPP2ACA. Importantly, the phylogenetic and structural studies suggest the Crk4-Cyc4 complex is limited to a minor group of the binary dividing apicomplexans.
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Proteínas Protozoarias , Toxoplasma , Toxoplasma/metabolismo , Toxoplasma/genética , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genética , Fase G2/genética , Centrosoma/metabolismo , División Celular , Ciclinas/metabolismo , Ciclinas/genéticaRESUMEN
Cyclins and cyclin-dependent kinases (CDKs) localize to the centrosome, but their significance in the cell cycle is unclear. Recently, Roberts et al. revealed that centrosomal cyclin B-CDK is required for mitotic entry and phosphorylation of substrates. This suggests that the centrosome acts as a signaling hub controlling the cell cycle.
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Ciclo Celular , Centrosoma , Quinasas Ciclina-Dependientes , Centrosoma/metabolismo , Humanos , Animales , Quinasas Ciclina-Dependientes/metabolismo , Mitosis , Transducción de Señal , Fosforilación , Ciclinas/metabolismoRESUMEN
BACKGROUND: Response to oxidative stress is universal in almost all organisms and the mitochondrial membrane protein, BbOhmm, negatively affects oxidative stress responses and virulence in the insect fungal pathogen, Beauveria bassiana. Nothing further, however, is known concerning how BbOhmm and this phenomenon is regulated. RESULTS: Three oxidative stress response regulating Zn2Cys6 transcription factors (BbOsrR1, 2, and 3) were identified and verified via chromatin immunoprecipitation (ChIP)-qPCR analysis as binding to the BbOhmm promoter region, with BbOsrR2 showing the strongest binding. Targeted gene knockout of BbOsrR1 or BbOsrR3 led to decreased BbOhmm expression and consequently increased tolerances to free radical generating compounds (H2O2 and menadione), whereas the ΔBbOsrR2 strain showed increased BbOhmm expression with concomitant decreased tolerances to these compounds. RNA and ChIP sequencing analysis revealed that BbOsrR1 directly regulated a wide range of antioxidation and transcription-associated genes, negatively affecting the expression of the BbClp1 cyclin and BbOsrR2. BbClp1 was shown to localize to the cell nucleus and negatively mediate oxidative stress responses. BbOsrR2 and BbOsrR3 were shown to feed into the Fus3-MAPK pathway in addition to regulating antioxidation and detoxification genes. Binding motifs for the three transcription factors were found to partially overlap in the promoter region of BbOhmm and other target genes. Whereas BbOsrR1 appeared to function independently, co-immunoprecipitation revealed complex formation between BbClp1, BbOsrR2, and BbOsrR3, with BbClp1 partially regulating BbOsrR2 phosphorylation. CONCLUSIONS: These findings reveal a regulatory network mediated by BbOsrR1 and the formation of a BbClp1-BbOsrR2-BbOsrR3 complex that orchestrates fungal oxidative stress responses.
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Ciclinas , Factores de Transcripción , Factores de Transcripción/genética , Peróxido de Hidrógeno , Ciclo Celular , Estrés Oxidativo , AntioxidantesRESUMEN
Cyclin F (encoded by CCNF gene) has been reported to be implicated in the pathobiology of several human cancers. However, its potential clinical significance in clear cell renal cell carcinoma (ccRCC) remains unknown. The present study aimed to evaluate the potential significance of cyclin F, assessed by immunohistochemical (IHC) staining and molecular (bioinformatics) techniques, as a prognostic marker in ccRCC in relation to clinicopathological features and outcomes. IHC staining was performed using two independent ccRCC tissue array cohorts, herein called tissue macroarray (TMA)_1 and tissue microarray (TMA)_2, composed of 108 ccRCCs and 37 histologically normal tissues adjacent to the tumor (NAT) and 192 ccRCCs and 16 normal kidney samples, respectively. The mRNA expression data were obtained from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) public datasets, followed by bioinformatics analysis of biological mechanisms underlying prognosis. The relationship between immune cell infiltration level and CCNF expression in ccRCC was investigated using the Tumor Immune Estimation Resource 2.0 (TIMER2) and Gene Expression Profiling Interactive Analysis 2 (GEPIA2). Cyclin F expression was significantly elevated in ccRCC lesions compared to both NAT and normal renal tissues. Likewise, CCNF mRNA was markedly increased in ccRCCs relative to non-cancerous tissues. In all analyzed cohorts, tumors with features of more aggressive behavior were more likely to display cyclin F/CCNF-high expression than low. Furthermore, patients with high cyclin F/CCNF expression had shorter overall survival (OS) times than those with low expression. In addition, multivariable analysis revealed that cyclin F/CCNF-high expression was an independent prognostic factor for poor OS in ccRCC. Enrichment analysis for mechanistically relevant processes showed that CCNF and its highly correlated genes initiate the signaling pathways that eventually result in uncontrolled cell proliferation. CCNF expression was also correlated with immune cell infiltration and caused poor outcomes depending on the abundance of tumor-infiltrating immune cells in ccRCC. Our findings suggest that cyclin F/CCNF expression is likely to have an essential role in ccRCC pathobiology through regulating multiple oncogenic signaling pathways and affecting the tumor immune microenvironment and may serve as prognostic biomarker and promising therapeutic target in ccRCC.
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Biomarcadores de Tumor , Carcinoma de Células Renales , Ciclinas , Regulación Neoplásica de la Expresión Génica , Neoplasias Renales , Femenino , Humanos , Masculino , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Carcinoma de Células Renales/genética , Carcinoma de Células Renales/mortalidad , Carcinoma de Células Renales/patología , Carcinoma de Células Renales/metabolismo , Ciclinas/metabolismo , Ciclinas/genética , Neoplasias Renales/genética , Neoplasias Renales/mortalidad , Neoplasias Renales/patología , Neoplasias Renales/metabolismo , PronósticoRESUMEN
Although mismatch repair (MMR) is essential for correcting DNA replication errors, it can also recognize other lesions, such as oxidized bases. In G0 and G1, MMR is kept in check through unknown mechanisms as it is error-prone during these cell cycle phases. We show that in mammalian cells, D-type cyclins are recruited to sites of oxidative DNA damage in a PCNA- and p21-dependent manner. D-type cyclins inhibit the proteasomal degradation of p21, which competes with MMR proteins for binding to PCNA, thereby inhibiting MMR. The ability of D-type cyclins to limit MMR is CDK4- and CDK6-independent and is conserved in G0 and G1. At the G1/S transition, the timely, cullin-RING ubiquitin ligase (CRL)-dependent degradation of D-type cyclins and p21 enables MMR activity to efficiently repair DNA replication errors. Persistent expression of D-type cyclins during S-phase inhibits the binding of MMR proteins to PCNA, increases the mutational burden, and promotes microsatellite instability.
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Ciclinas , Reparación de la Incompatibilidad de ADN , Animales , Ciclinas/genética , Antígeno Nuclear de Célula en Proliferación/genética , Antígeno Nuclear de Célula en Proliferación/metabolismo , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/genética , Interfase , Mamíferos/metabolismoRESUMEN
Meiosis is a complex variant of the mitotic cell cycle, and as such relies on many of the same proteins involved in mitosis, but utilizes these in novel ways. As in mitosis, Cdk1 and its cyclin partners, Cyclin A, B, and B3 are required at multiple steps in meiosis. Here, we study the effect of stabilized forms of the three mitotic cyclins to study the consequences of failure to degrade the cyclins in meiosis. We find that stabilized Cyclin B3 promotes ectopic microtubule polymerization throughout the egg, dependent on APC/C activity and apparently due to the consequent destruction of Cyclin A and Cyclin B. We present data that suggests CycB, and possibly CycA, can also promote APC/C activity at specific stages of meiosis. We also present evidence that in meiosis APC/CCort and APC/CFzy are able to target Cyclin B via a novel degron. Overall, our findings highlight the distinct functions of the three mitotic Cdk-cyclin complexes in meiosis.
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Ciclina B , Ciclinas , Proteínas de Drosophila , Meiosis , Mitosis , Animales , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Ciclina B/metabolismo , Ciclina B/genética , Ciclinas/metabolismo , Ciclinas/genética , Ciclina A/metabolismo , Drosophila/metabolismo , Drosophila/genética , Microtúbulos/metabolismo , Ciclosoma-Complejo Promotor de la Anafase/metabolismo , Ciclosoma-Complejo Promotor de la Anafase/genética , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genéticaRESUMEN
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the degeneration of motor neurons. Mutations in the cyclin F (CCNF) and fused in sarcoma (FUS) genes have been associated with ALS pathology. In this study, we aimed to investigate the functional role of CCNF and FUS in ALS by using genome editing techniques to generate zebrafish models with genetic disruptions in these genes. Sequence comparisons showed significant homology between human and zebrafish CCNF and FUS proteins. We used CRISPR/Cas9 and TALEN-mediated genome editing to generate targeted disruptions in the zebrafish ccnf and fus genes. Ccnf-deficient zebrafish exhibited abnormal motor neuron development and axonal outgrowth, whereas Fus-deficient zebrafish did not exhibit developmental abnormalities or axonopathies in primary motor neurons. However, Fus-deficient zebrafish displayed motor impairments in response to oxidative and endoplasmic reticulum stress. The Ccnf-deficient zebrafish were only sensitized to endoplasmic reticulum stress, indicating that ALS genes have overlapping as well as unique cellular functions. These zebrafish models provide valuable platforms for studying the functional consequences of CCNF and FUS mutations in ALS pathogenesis. Furthermore, these zebrafish models expand the drug screening toolkit used to evaluate possible ALS treatments.
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Esclerosis Amiotrófica Lateral , Ciclinas , Enfermedades Neurodegenerativas , Proteína FUS de Unión a ARN , Pez Cebra , Animales , Humanos , Esclerosis Amiotrófica Lateral/metabolismo , Ciclinas/metabolismo , Neuronas Motoras/patología , Enfermedades Neurodegenerativas/metabolismo , Proteínas/metabolismo , Proteína FUS de Unión a ARN/genética , Proteína FUS de Unión a ARN/metabolismo , Pez Cebra/metabolismoRESUMEN
BACKGROUND: Tyrosine kinase inhibitors (TKIs) are crucial in the targeted treatment of advanced colorectal cancer (CRC). Anlotinib, a multi-target TKI, has previously been demonstrated to offer therapeutic benefits in previous studies. Circular RNAs (circRNAs) have been implicated in CRC progression and their unique structural stability serves as promising biomarkers. The detailed molecular mechanisms and specific biomarkers related to circRNAs in the era of targeted therapies, however, remain obscure. METHODS: The whole transcriptome RNA sequencing and function experiments were conducted to identify candidate anlotinib-regulated circRNAs, whose mechanism was confirmed by molecular biology experiments. CircHAS2 was profiled in a library of patient-derived CRC organoids (n = 22) and patient-derived CRC tumors in mice. Furthermore, a prospective phase II clinical study of 14 advanced CRC patients with anlotinib-based therapy was commenced to verify drug sensitivity (ClinicalTrials.gov identifier: NCT05262335). RESULTS: Anlotinib inhibits tumor growth in vitro and in vivo by downregulating circHAS2. CircHAS2 modulates CCNE2 activation by acting as a sponge for miR-1244, and binding to USP10 to facilitate p53 nuclear export as well as degradation. In parallel, circHAS2 serves as a potent biomarker predictive of anlotinib sensitivity, both in patient-derived organoids and xenograft models. Moreover, the efficacy of anlotinib inclusion into the treatment regimen yields meaningful clinical responses in patients with high levels of circHAS2. Our findings offer a promising targeted strategy for approximately 52.9% of advanced CRC patients who have high circHAS2 levels. CONCLUSIONS: CircHAS2 promotes cell proliferation via the miR-1244/CCNE2 and USP10/p53/CCNE2 bidirectional axes. Patient-derived organoids and xenograft models are employed to validate the sensitivity to anlotinib. Furthermore, our preliminary Phase II clinical study, involving advanced CRC patients treated with anlotinib, confirmed circHAS2 as a potential sensitivity marker.