OBJECTIVE: To investigate the fate and underlying mechanisms of G2 phase arrest in cancer cells elicited by ionizing radiation (IR). METHODS: Human melanoma A375 and 92-1 cells were treated with X-rays radiation or Aurora A inhibitor MLN8237 (MLN) and/or p21 depletion by small interfering RNA (siRNA). Cell cycle distribution was determined using flow cytometry and a fluorescent ubiquitin-based cell cycle indicator (FUCCI) system combined with histone H3 phosphorylation at Ser10 (pS10 H3) detection. Senescence was assessed using senescence-associated-β-galactosidase (SA-β-Gal), Ki67, and γH2AX staining. Protein expression levels were determined using western blotting. RESULTS: Tumor cells suffered severe DNA damage and underwent G2 arrest after IR treatment. The damaged cells did not successfully enter M phase nor were they stably blocked at G2 phase but underwent mitotic skipping and entered G1 phase as tetraploid cells, ultimately leading to senescence in G1. During this process, the p53/p21 pathway is hyperactivated. Accompanying p21 accumulation, Aurora A kinase levels declined sharply. MLN treatment confirmed that Aurora A kinase activity is essential for mitosis skipping and senescence induction. CONCLUSION Persistent p21 activation during IR-induced G2 phase blockade drives Aurora A kinase degradation, leading to senescence <i>viai> mitotic skipping.
Humans ; Aurora Kinase A/metabolism* ; Cell Line, Tumor ; Mitosis ; Cell Cycle ; Radiation, Ionizing ; RNA, Small Interfering/metabolism* ; Cyclin-Dependent Kinase Inhibitor p21/metabolism*

Meiotic initiation is a critical step in gametogenesis. Recently, some genes required for meiotic initiation have been identified. However, meiosis-initiating factors and the underlying mechanisms are far from being fully understood. We have established a long-term culture system of spermatogonial stem cells (SSCs) and an <i>in vitroi> model of meiotic initiation using mouse SSCs. Our previous study revealed that the RNA-binding protein RBFOX2 may regulate meiotic initiation, but the role and the mechanism need to be further elucidated. In this study, we constructed RBFOX2 knockdown SSC lines by using lentivirus-mediated gene delivery method, and found that the knockdown SSCs underwent normal self-renewal, mitosis and differentiation. However, they were unable to initiate meiosis when treated with retinoic acid, and they underwent apoptosis. These results indicate that RBFOX2 plays an essential role in meiotic initiation of spermatogonia. This work provides new clues for understanding the functions of RNA-binding proteins in meiotic initiation.
Mice ; Male ; Animals ; Spermatogonia/metabolism* ; Meiosis/genetics* ; Cell Differentiation ; Tretinoin/pharmacology* ; Mitosis ; Testis/metabolism*

Spindle assembly checkpoint (SAC) is a protective mechanism for cells to undergo accurate mitosis. SAC prevented chromosome segregation when kinetochores were not, or incorrectly attached to microtubules in the anaphase of mitosis, thus avoiding aneuploid chromosomes in daughter cells. Aneuploidy and altered expression of SAC component proteins are common in different cancers, including lung cancer. Therefore, SAC is a potential new target for lung cancer therapy. Five small molecule inhibitors of monopolar spindle 1 (MPS1), an upstream component protein of SAC, have entered clinical trials. This article introduces the biological functions of SAC, summarizes the abnormal expression of SAC component proteins in various cancers and the research progress of MPS1 inhibitors, and expects to provide a reference for the future development of lung cancer therapeutic strategies targeting SAC components.
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Humans ; Cell Cycle Proteins/metabolism* ; Spindle Apparatus/metabolism* ; Protein Serine-Threonine Kinases/metabolism* ; M Phase Cell Cycle Checkpoints/genetics* ; Lung Neoplasms/metabolism*

CUDC-101, an effective and multi-target inhibitor of epidermal growth factor receptor (EGFR), histone deacetylase (HDAC), and human epidermal growth factor receptor 2 (HER2), has been reported to inhibit many kinds of cancers, such as acute promyelocytic leukemia and non-Hodgkin's lymphoma. However, no studies have yet investigated whether CUDC-101 is effective against myeloma. Herein, we proved that CUDC-101 effectively inhibits the proliferation of multiple myeloma (MM) cell lines and induces cell apoptosis in a time- and dose-dependent manner. Moreover, CUDC-101 markedly blocked the signaling pathway of EGFR/phosphoinositide-3-kinase (PI3K) and HDAC, and regulated the cell cycle G2/M arrest. Moreover, we revealed through in vivo experiment that CUDC-101 is a potent anti-myeloma drug. Bortezomib is one of the important drugs in MM treatment, and we investigated whether CUDC-101 has a synergistic or additive effect with bortezomib. The results showed that this drug combination had a synergistic anti-myeloma effect by inducing G2/M phase blockade. Collectively, our findings revealed that CUDC-101 could act on its own or in conjunction with bortezomib, which provides insights into exploring new strategies for MM treatment.
Humans ; Antineoplastic Agents/therapeutic use* ; Apoptosis ; Bortezomib/pharmacology* ; Cell Line, Tumor ; Cell Proliferation ; ErbB Receptors/antagonists & inhibitors* ; G2 Phase Cell Cycle Checkpoints ; Histone Deacetylase Inhibitors/pharmacology* ; Histone Deacetylases/metabolism* ; M Cells ; Multiple Myeloma/drug therapy*

RBM46 is a germ cell-specific RNA-binding protein required for gametogenesis, but the targets and molecular functions of RBM46 remain unknown. Here, we demonstrate that RBM46 binds at specific motifs in the 3'UTRs of mRNAs encoding multiple meiotic cohesin subunits and show that RBM46 is required for normal synaptonemal complex formation during meiosis initiation. Using a recently reported, high-resolution technique known as LACE-seq and working with low-input cells, we profiled the targets of RBM46 at single-nucleotide resolution in leptotene and zygotene stage gametes. We found that RBM46 preferentially binds target mRNAs containing GCCUAU/GUUCGA motifs in their 3'UTRs regions. In <i>Rbm46i> knockout mice, the RBM46-target cohesin subunits displayed unaltered mRNA levels but had reduced translation, resulting in the failed assembly of axial elements, synapsis disruption, and meiotic arrest. Our study thus provides mechanistic insights into the molecular functions of RBM46 in gametogenesis and illustrates the power of LACE-seq for investigations of RNA-binding protein functions when working with low-abundance input materials.
Animals ; Mice ; 3' Untranslated Regions/genetics* ; Cell Cycle Proteins/metabolism* ; Gametogenesis/genetics* ; Meiosis/genetics* ; Nuclear Proteins/genetics* ; RNA-Binding Proteins/genetics*

Cell Cycle Checkpoints/genetics* ; Checkpoint Kinase 1/metabolism* ; Heterozygote ; Humans ; Mitosis/genetics* ; Mutation ; Zygote/metabolism*

Aurora kinase A (AURKA),a family member of aurora kinases,is involved in mitotic entry,maturation and separation of centrosome,assembly and stabilization of bipolar spindle,and condensation and separation of chromosome.Studies have demonstrated that AURKA plays a similar role in meiosis,while the specific mechanism and the similarities and differences in its role between meiosis and mitosis remain unclear.Therefore,we reviewed the studies about the localization and activation of AURKA in oocyte meiosis,and compared the role of AURKA in regulating spindle formation,activating spindle assembly checkpoint,and correcting the kinetochore-microtubule attachment between the meiosis of oocytes and the mitosis of somatic cells.This review will lay a theoretical foundation for revealing the mechanism of AURKA in the regulation of cell division and for the clinical research related to cancer and reproduction.
Aurora Kinase A/genetics* ; Cell Cycle Proteins/genetics* ; Chromosome Segregation ; Humans ; Meiosis ; Oocytes

During mitosis, the allocation of genetic material concurs with organelle transformation and distribution. The coordination of genetic material inheritance with organelle dynamics directs accurate mitotic progression, cell fate determination, and organismal homeostasis. Small GTPases belonging to the Ras superfamily regulate various cell organelles during division. Being the key regulators of membrane dynamics, the dysregulation of small GTPases is widely associated with cell organelle disruption in neoplastic and non-neoplastic diseases, such as cancer and Alzheimer's disease. Recent discoveries shed light on the molecular properties of small GTPases as sophisticated modulators of a remarkably complex and perfect adaptors for rapid structure reformation. This review collects current knowledge on small GTPases in the regulation of cell organelles during mitosis and highlights the mediator role of small GTPase in transducing cell cycle signaling to organelle dynamics during mitosis.
Humans ; Mitosis ; Monomeric GTP-Binding Proteins ; Neoplasms ; Organelles/physiology* ; Signal Transduction

The development of female germ cells can be mainly divided into two stages: fetal germ cells and oocytes in folliculogenesis after puberty. Mitosis-meiosis transition, meiosis arrest and re-activation are the key phases of the development. Several phases may be characterized by their distinct molecular events, which involve precise regulation of gene expression and interaction with corresponding gonadal niche cells. In recent years, single-cell transcriptome studies have clarified phase-specific patterns of gene expression, signaling pathways and epigenetic modification during oogenesis and folliculogenesis. These works have provided important insights into the development of female germ cells and pathogenesis of germ-cell related diseases, which may promote clinical application of reproductive genetic research.
Female ; Germ Cells ; Humans ; Meiosis ; Oocytes ; Oogenesis/genetics* ; Signal Transduction

Oocyte cryopreservation is widely used for clinical and social reasons. Previous studies have demonstrated that conventional slow-freezing cryopreservation procedures, but not storage time, can alter the gene expression profiles of frozen oocytes. Whether vitrification procedures and the related frozen storage durations have any effects on the transcriptomes of human metaphase II oocytes remain unknown. Four women (30-32 years old) who had undergone IVF treatment were recruited for this study. RNA-Seq profiles of 3 fresh oocytes and 13 surviving vitrified-thawed oocytes (3, 3, 4, and 3 oocytes were cryostored for 1,2, 3, and 12 months) were analyzed at a single-cell resolution. A total of 1987 genes were differentially expressed in the 13 vitrified-thawed oocytes. However, no differentially expressed genes were found between any two groups among the 1-, 2-, 3-, and 12-month storage groups. Further analysis revealed that the aberrant genes in the vitrified oocytes were closely related to oogenesis and development. Our findings indicated that the effects of vitrification on the transcriptomes of mature human oocytes are induced by the procedure itself, suggesting that long-term cryostorage of human oocytes is safe.
Adult ; Cryopreservation ; Female ; Humans ; Metaphase ; Oocytes ; RNA-Seq ; Vitrification