Cell cycle regulation of deoxycytidine kinase

Abstract

Deoxycytidine kinase enzyme activity and deoxycitidine kinase mRNA content were determined at different positions of the cell cycle in permanent cell lines. There was no variation of deoxycytidine kinase activity during the cell cycle in two cell lines, whereas in two other lines the enzyme activity was induced (IO-and 15-fold) at the GUS boundary. In contrast, the level of deoxycytidine kinase mRNA never displayed any cell cycle-dependent changes. The decay of enzymatic activity was measured after addition of cycloheximide in different phases of the cell cycle; the enzyme was much more stable in cells with constant activity. We suggest that post-transcriptional mechanisms account for the periodic behaviour of the enzyme activity, and that whether this regulation can be detected depends on the half-life of deoxycytidine kinase.

Expression of the cyclin‐dependent kinase inhibitor p16 during the ongoing cell cycle

“…3) (mean of all elutriations 78%). In general, the separation data were very comparable to earlier obtained results with the same or similar cells [18]. Since the quality of separation was that comparable, we concluded that any differences possibly occuring during the cell cycle regulation between the studied cell lines would not be caused by experimental variations.…”

“…Separation of cell cycle phases by centrifugal elutriation was performed as described [18]. The elutriation system consisted of a Beckman J2-21 M centrifuge and a JE-6B rotor eqipped with the standard separation chamber.…”

Conserved gene structure and transcription factor sites in the human and mouse deoxycytidine kinase genes1

“…This is in contrast to studies on crude protein extract of human muscle and brain that contain very low levels of dCK [5,6]. The reason for the discrepancy is not known, but it has been suggested that expression of dCK may be regulated at the post‐transcriptional level in certain cell types [19]. It is presently not known whether the lymphoblast predominant expression of dCK is regulated at the transcriptional or post‐transcriptional level and further studies will be required to clarify this issue.…”