The ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C) is activated at prometaphase by mitotic phosphorylation and binding of its activator, Cdc20. This initiates cyclin A degradation, whereas cyclin B1 is stabilized by the spindle checkpoint. Upon checkpoint release, the RXXL destruction box (D box) was proposed to direct cyclin B1 to core APC/C or Cdc20. In this study, we report th...

Protein complex of cyclin B1 and cyclin-dependent protein kinase 1 induces phosphorylation of key substrates that mediate cell cycle transition during the G(2)-M phase. It is believed that cyclin B1 accumulates in the S phase of the cell cycle and reaches the maximal level at mitosis but is absent in G(1)-phase cells. In the present study, we demonstrated that cyclin B1 was expressed in the arr...

BACKGROUND To better understand the relationship between mitotic delay and the disruption of cyclin B1 and p21 in x-irradiated fibroblasts, studies were carried out to establish correlations between the downregulation of cyclin B1 by the cyclin kinase inhibitor (CKI) p21 and the induction of mitotic delay in the NIH3T3 fibroblast. MATERIALS AND METHODS Cell cycle kinetics were used to analyze...

BACKGROUND At M phase, cyclin B1 is phosphorylated in the cytoplasmic retention sequence (CRS), which is required for nuclear export. During interphase, cyclin B1 shuttles between the nucleus and the cytoplasm because constitutive nuclear import is counteracted by rapid nuclear export. In M phase, cyclin B moves rapidly into the nucleus coincident with its phosphorylation, an overall movement t...

Cyclin B1 is a key mitotic cyclin in the G2-M phase transition of the cell cycle and is overexpressed in various malignant tumors. Numerous studies have reported contradictory evidences of the correlation between cyclin B1 expression and prognosis in human solid tumors. To address this discrepancy, we conducted a meta-analysis with 17 published studies searched from PubMed and Medline. Cyclin B...

OBJECTIVES Aberrant expression of cyclin B1, a cell cycle regulator, is related to prognosis in various human malignancies. Additionally, cytoplasmic expression of cyclin B1 in epithelial malignancies is associated with a specific T-cell response and presumably also a humoral immune response. We therefore investigated (i) whether a similar expression pattern could be detected in native human ac...

Within the mammalian ovary, oocytes remain arrested at G2 for several years. Then a peri-ovulatory hormonal cue triggers meiotic resumption by releasing an inhibitory phosphorylation on the kinase Cdk1. G2 arrest, however, also requires control in the concentrations of the Cdk1-binding partner cyclin B1, a process achieved by anaphase-promoting complex (APC(Cdh1)) activity, which ubiquitylates ...

Cyclin B1, a key component in the control of cell cycle progression from G(2) to M phase, has been implicated in tumorigenesis and the development of malignancy. However, the underlying mechanism by which cyclin B1 acts as an important oncogenic molecule remains largely unknown. Here we show that ectopic expression of cyclin B1 promotes cell proliferation, enhances cell motility and migration a...

Cyclin B1 tracking provides information on cell cycle progression and cell-cycle regulator dynamics. We have developed a mathematical model which describes the continuous tracking of cyclin B1 through the cell cycle at the single cell level, including interactions with the cyclin B1 inhibitor, p21. The cell line used is a cancer cell line, human osteosarcoma (U-2 OS). An examination of the sens...

We have studied changes in cyclin A- and B1-dependent kinases during apoptosis induced in human promyelocytic leukemia (HL60) cells treated with the topoisomerase I inhibitor camptothecin. We found that cyclin B1/Cdc2 kinase activity transiently increases within 30 min after camptothecin treatment. This increase is followed by a rapid inactivation of the cyclin B1/Cdc2 kinase that is associated...