Cell Cycle : Runs like "Clock" Work

Abstract

The circadian clock is the intrinsic timekeeping device that exists within all living organisms and whose function is to integrate information about the light and dark phases of a day into the biological processes that occur in order to sustain life. This integration manifests as oscillations in the expression of molecules or in the rhythmicity of certain processes with a period of ~24 hours. The master pacemaker resides in a region of the brain called the suprachiasmatic nucleus (SCN) and its job is to detect when it is light and dark and pass this information onto secondary oscillators that reside in almost all tissues of a body, which in turn modify the processes that take place in that tissue. On the molecular level, the circadian circuit consists of a network of transcriptional and translational autoregulatory feedback loops that result in the temporal expression of core clock proteins. Links have been found between the circadian clock and the progression of the cell cycle, indicating that cell division is, in part, regulated by day and night rhythms. Some of the proteins that mediate this connection have been identified. Due to this link, the deregulation of circadian rhythmicity may also lead to aberrant cell cycling and increased susceptibility to diseases such as cancer. On the other hand, this intertwinement of the two processes can be utilized in anticancer treatments, so that the efficacy can be maximized and the toxicity minimized by taking into account the time of day that they are administered.