Cell cycle components

Tumor-suppressor genes encode proteins that directly or indirectly slow progression through the cell cycle, checkpoint-control proteins that arrest the cell cycle, components of growth-inhibiting signaling pathways, pro-apoptotlc proteins, and DNA-repalr enzymes. 

Thus, the suppression of cell cycle components by natural polyphenol compounds could be an effective strategy in abating the proliferation of tumor cells in vivo. 

Whether the DNA replication checkpoint directly affects the Plxl activation pathway for Cdc25C has not yet been established. It is possible that the replication checkpoint arrests the cell cycle prior to initiation of the Plxl kinase cascade. Further characterization of upstream components of the cascade should reveal whether it is directly regulated by replication checkpoint activation. Such a characterization will also have importance for other M phase events, inasmuch as Plxl also regulates bipolar spindle formation, APC activation and cytokinesis (Qian et al 1998, 1999). These multiple functions of Plxl are associated with changes in localization of Plxl, and are most likely mediated by protein—protein interaction with the polo box motif in the non-catalytic C-terminal half of Plxl. 

It is uncertain whether the intrinsic timer in OPCs primarily controls the onset of differentiation, the cessation of proliferation, or both. It seems likely, however, that the timer at some point interacts with the cell-cycle control system that regulates progress through the cell cycle. As the cells stop dividing and differentiate in Gl, it is the part of the control system that operates in G1 that is most likely to be relevant. In principle, the components of the cell-cycle control system could be components of the timer. The timer, for example, could depend on a decrease in one or more positive intracellular regulators, such as a cyclin or a Cdk... 

Amhros No one has looked at that directly. Ideally, one would like to monitor the phosphorylation state of different components of the signalling pathway and the status of key transcription factors, and so on. In principle this is feasible, and we would predict that we might find a cell cycle gating of one of those steps. 

A narrow beam, attainable with Raman, was used by Schuster et al.4 to characterize the population distribution in Clostridium cultures. The technique was applied to the acetone-butanol (ABE) fermentation process in which the solventogenic Clostridia go through a complex cell cycle. After drying the cells on calcium fluoride carriers, single-cell spectra were obtained. Cells of different morphology showed different spectra. A number of cell components could be detected and varied in quantity. The approach was seen to be far faster than conventional methods. 

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