Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A C6 beta-chemokine, CKbeta8-1, suppressed the colony formation of CD34+ cells of human cord blood (CB). Molecular mechanisms involved in CKbeta8-1-medicated suppression of colony formation of CD34+ cells are not known. To address this issue, the level of various G1/S cell cycle regulating proteins in CKbeta8-1-treated CD34+ cells were compared with those in untreated CD34+ cells. CKbeta8-1 did not significantly alter the expression of the G1/S cycle regulation proteins (cyclin D1, D3, and E), CDK inhibitor (p27and Rb), and other cell proliferation regulation protein (p53) in CB CD34+ cells. Here we describe an in vitro system in which CB CD34+ cells were committed to a multipotent progenitor lineage of colony forming units-granulocyte/macrophage (CFU-GM) by a simple combination of recombinant human (rh) GM-CSF and rhIL-3. In this culture system, we found that cyclin E protein appeared later and disappeared faster in the CKbeta8-1-treated cells than in the control cells during CFU-GM lineage development. These findings suggested that cyclin E may play a role in suppressing the colony formation of CFU-GM by CKbeta8-1.
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PMID:CKbeta8-1 alters expression of cyclin E in colony forming units-granulocyte macrophage (CFU-GM) lineage from human cord blood CD34+ cells. 1639 23

The abrupt activation of CDK1 during mitotic entry requires suppression of CDK activity until a threshold concentration of cyclin B is synthesized, triggering the activation of a large pool of CDK. The cellular mechanisms that define the concentration of cyclin B at which the threshold occurs are unknown. Here we demonstrate that this threshold is regulated by Aurora-A kinase and phosphatase Inhibitor-2. In Xenopus CSF extracts that actively translate cyclin B1, immunodepletion of either endogenous xInhibitor-2 or endogenous xAurora-A caused delayed mitotic entry and normal timing was restored by addition of the respective recombinant proteins. Aurora-A depleted extracts also could be rescued by the addition of full-length xInhibitor-2, but not an xInhibitor-2 truncated of its PP1 binding motif. This demonstrates that inhibition of PP1 was required to compensate for the absence of Aurora-A. To test the hypothesis that the delays in mitotic entry in CSF extracts were due to increases in cyclin B thresholds, we employed interphase extracts, which are driven into mitosis by the addition of recombinant cyclin B in a nonlinear (threshold) dose-response. Neutralization of endogenous xInhibitor-2 or xAurora with antibodies increased the cyclin B threshold concentration. Alternatively, the addition of exogenous Aurora-A or Inhibitor-2 lowered the concentration of cyclin B that triggered CDK activation. Because the cyclin B threshold could be raised or lowered by changing the amount of either Aurora-A or Inhibitor-2, the results demonstrate these regulatory proteins are involved in a signaling loop required to create the switching behavior characteristic of mitotic entry.
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PMID:Aurora-A kinase and inhibitor-2 regulate the cyclin threshold for mitotic entry in Xenopus early embryonic cell cycles. 1696 36

Fertilization in mammals is accompanied by Ca(2+) oscillations in the egg cytoplasm, leading to exit from meiosis and entry into the first embryonic cell cycle. The signal transduction pathway linking these Ca(2+) changes to cell-cycle related kinases has not yet been fully elucidated, but involves activation of calmodulin-dependent kinase II (CaMKII). Here, we develop a computational model to investigate the mechanism by which cell cycle resumption can be sensitive to the temporal pattern of Ca(2+) increases. Using a model for CaMKII activation that reproduces the frequency sensitivity of this kinase, simulations confirm that Ca(2+) spikes are accompanied by in phase variations in the level of CaMKII activity and suggest that in most mammalian species, Ca(2+) spikes are well suited to maximize CaMKII activation. The full model assumes that CaMKII brings about a decrease in the level of cyclinB-cdk1 by two pathways, only one of which is CSF-dependent. Parameters are selected to account for the experimental observations where mouse eggs were artificially activated by different Ca(2+) stimulatory protocols. The model is then used in the context of 'assisted oocyte activation (AOA)' to investigate why the best rates of successful activation are obtained when eggs are submitted to two applications of Ca(2+) ionophores.
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PMID:Oscillatory Ca2+ dynamics and cell cycle resumption at fertilization in mammals: a modelling approach. 2020 38


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