Project description:We addressed the role of cell cycle regulator CDK1 during differentiation by either inhibiting its activity with the specific inhibitor RO3306 (10µM) or by knocking its expression down using specific shRNAs, during mesendoderm differentiation. Human pluripotent stem cells (H9 cells) were synchronized in their cell cycle and then induced to differentiate into mesendoderm for 24h. shRNAs against CDK1 were induced 4 days before starting the differentiation. The CDK1 inhibitor was added to the medium 8h after the induction of differentiation. At the end of the experiment, the cells were harvested and processed for total RNA extraction. RNA-IP was carried out using RiboCluster Profiler RIP-Assay Kit (MBL) following the manufacture’s recommendations.
Project description:We show that Arid1a maintains tissue homeostasis through promoting cell cycle exit and differentiation of TACs by inhibiting the Aurka-Cdk1 axis.
Project description:tRNA genes are transcribed by RNA polymerase III (RNAPIII). During recent years it has become clear that RNAPIII activity is strictly regulated by the cell in response to environmental cues and the homeostatic status of the cell. However, the molecular mechanisms that control RNAPIII activity to regulate the amplitude of tDNA transcription in normally cycling cells are not well understood. Here, we show that tRNA levels fluctuate during the cell cycle and reveal the underlying molecular mechanism. The cyclin Clb5 recruits the cyclin dependent kinase Cdk1 to tRNA genes to boost tDNA transcription during S phase. At tDNA genes, Cdk1 promotes the recruitment of TFIIIC, stimulates the interaction between TFIIIB and TFIIIC, and increases the dynamics of RNA polymerase III in vivo. Furthermore, we identified Bdp1 as an important Cdk1 substrate in this process. Preventing Bdp1 phosphorylation prevented cell cycle-dependent recruitment of TFIIIC and abolished the cell cycle-induced increase in tDNA transcription. Our findings demonstrate that under optimal growth conditions Cdk1 gates tRNA synthesis in S phase by regulating the RNAPIII machinery, revealing a direct link between the cell cycle and RNAPIII activity.
Project description:Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive Schwann cell-derived sarcomas that are sporadic or associated with NF1 gene mutations. Traditional therapies are `usually ineffective for treating MPNSTs, so new targets need to be identified for the treatment of MPNSTs. In the present study, the role of the mitochondrial translocator protein (TSPO) in the regulation of cell proliferation and the cell cycle in MPNSTs was investigated. TSPO expression was lower in MPNSTs than in NFs. Loss-of-function experiments revealed that TSPO deficiency promoted MPNST cell growth, migration, and invasion and influenced the cell cycle in vitro and in vivo. In addition, TSPO depletion suppressed cell apoptosis by downregulating the expression of caspase-3, caspase-8, HSP60, p27, p53, and BCL-2 and suppressed the cell cycle by upregulating CDK1, CDK2, CCNB1 and CCNA2. Furthermore, CDK1 was determined to be an upstream target of TSPO-mediated regulation via RNA-seq, qPCR, and Western blotting. Specifically, depletion of CDK1 weakened the effect of TSPO deficiency on cell proliferation and migration. More importantly, CDK1 knockdown induced significant cell cycle arrest in the G2/M phase. In summary, TSPO deficiency regulates the cell cycle in MPNSTs by targeting CDK1, which may be an effective molecular target for prognosis evaluation and treatment.
Project description:Dihydroartemisinin (DHA), a well-known antimalarial drug, has been widely investigated as its anti-tumor effects in multiple malignancies. However, its effects and regulatory mechanisms in colorectal cancer (CRC) are still unproved. In this study, the in vitro experiments including CCK8, EdU, Transwell, flow cytometry analyses and in vivo tumorigenesis model were conducted to assess the effects of DHA on the bio-behaviors of CRC cells. Additionally, RNA-seq combined with gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses was used to obtain the targets of DHA and these were verified by molecular docking, qRT-PCR and Western blot. As a result, we found that DHA significantly suppressed the proliferation, DNA synthesis and invasive capabilities, and induced cell apoptosis and cell cycle arrest in HCT116, DLD1 and RKO cells in vitro and in vivo. Further analyses indicated that the targets of DHA were predominantly enriched in cell cycle-associated pathways, including CDK1, CCNB1 and PLK1, and DHA could bind with CDK1/CCNB1 complex and inhibit the activation of CDK1/CCNB1/PLK1 signaling. Moreover, cucurbitacin E, a specific inhibitor of CDK1/CCNB1 axis enhanced the inhibitory effects of DHA on DNA synthesis and colony formation in HCT116 and DLD1 cells. In short, DHA could suppress the tumorigenesis and cycle progression of CRC cells by targeting CDK1/CCNB1/PLK1 signaling.
Project description:In this study, we found that in ES cells the majority of Cdk1 substrates are localized on chromatin. Cdk1 phosphorylates a large number of proteins involved in epigenetic regulation, including writers and erasers of all major histone marks. High levels of Cdk1 in ES cells phosphorylate and partially inactivate Dot1l, the histone H3 lysine 79 methyltransferase responsible for placing activating H3K79 marks on gene bodies. Decrease of Cdk1 activity during ES cell differentiation de-represses Dot1l, thereby allowing coordinated expression of differentiation genes. These analyses indicate that Cdk1 functions to maintain the epigenetic identity of ES cells.
Project description:Analysis of gene expression across the cell cycle from wild type cells, and cells expressing alleles of Yox1, Yhp1, Hcm1, and Tos4 that cannot be phosphorylated by Cdk1. Expression of S-phase and M/G1 transcripts are downregulated when phosphorylation of these factors is blocked, demonstrating that Cdk1 promotes expression of late cell cycle genes.
Project description:Analysis of gene expression across the cell cycle from wild type cells, and cells expressing alleles of Yox1, Yhp1, Hcm1, and Tos4 that cannot be phosphorylated by Cdk1. Expression of S-phase and M/G1 transcripts are downregulated when phosphorylation of these factors is blocked, demonstrating that Cdk1 promotes expression of late cell cycle genes. These experiments are two-color hybridizations of RNA isolated from synchronized wild type (WT) or phosphomutant (4P) cells, compared to RNA from asyncrhonous wild type cells in mid-log phase. Wild type and mutant cells were synchronized in G1 phase, released into the cell cycle and samples collected at 15 minute intervals. Each time course was carried out in duplicate, the replicate experiment was performed as a dye swap.
Project description:Purpose: Determine whether Cdk1 only regulates a specific subset of tDNAs, or whether Cdk1 has a more global impact on tDNA expression; Method: We study the expression of tRNA genes in WT cells and cdk1-as1 mutants during S phase by small-RNAseq; Result: We found that expression of at least 77% of all tDNAs is significantly downregulated in S-phase in the cdk1-as1 mutant compared with the WT strain; Conclussions: Cdk1 promotes transcription of the majority of tRNA genes during the cell cycle.
Project description:Molecular programs involved in embryogenesis are frequently upregulated in oncogenic dedifferentiation and metastasis. However, their precise roles and regulatory mechanisms remain elusive. Here, we showed that CDK1 phosphorylation of TFCP2L1, a pluripotency-associated transcription factor, orchestrated pluripotency and cell-cycling in embryonic stem cells (ESCs) and was aberrantly activated in aggressive bladder cancers (BCs). In murine ESCs, the protein interactome and transcription targets of Tfcp2l1 indicated its involvement in cell-cycle regulation. Tfcp2l1 was phosphorylated at Thr177 by Cdk1, which affected ESC cell-cycle progression, pluripotency, and differentiation. LC-MS was used to characterize thr177 phosphorylation in TFCP2L1 protein obtained by IP experiment and kinase assay. The CDK1-TFCP2L1 pathway was activated in human BC cells, stimulating their proliferation, self-renewal, and invasion. Lack of TFCP2L1 phosphorylation impaired the tumorigenic potency of BC cells in a xenograft model. In patients with BC, high co-expression of TFCP2L1 and CDK1 was associated with unfavorable clinical characteristics including tumor grade, lymphovascular and muscularis propria invasion, and distant metastasis and was an independent prognostic factor for cancer specific survival. These findings demonstrate the molecular and clinical significance of CDK1-mediated TFCP2L1 phosphorylation in stem-cell pluripotency and in the tumorigenic stemness features associated with BC progression.