Circadian Clock - Regulation of Circadian Oscillators

Regulation of Circadian Oscillators

Circadian oscillators are simply oscillators with a period of approximately 24 hours. In response to light stimulus the body corresponds with a system and network of pathways that work together to determine the biological day and night. The regulatory networks involved in keeping the clock precise span over a range of post-translation regulation mechanisms. Circadian oscillators may be regulated by phosphorylation, SUMOylation, ubiquitination, and histone acetylation and deacetylation, the covalent modification of the histone tail which controls the level of chromatin structures causing the gene to be expressed more readily. Methylation of a protein structure adds a methyl group and regulates the protein function or gene expression and in histone methylation gene expression is either suppressed or activated through changing the DNA sequence. Histones go through an acetylation, methylation and phosphorylation process but the major structural and chemical changes are when enzymes histone acetyltransferases (HAT) and histone deacetylases (HDAC) add or remove acetyl groups from the histone causing a major change in DNA expression. By changing DNA expression, histone acetylation and methylation regulate how the circadian oscillator operates.