Investigating the behavioural and molecular functions of Cry1 and Cry2 using mouse mutants

Abstract

Endogenous circadian clocks generate rhythms of physiology and behaviour that are synchronised to the environment, principally through the light-dark cycle. In mammals, the circadian clock is dependent on interlocked feedback loops that involve several clock elements such as cryptochromes (Cryl and Cry2). Post-translational modifications control intracellular trafficking, functionality and degradation of CRY proteins which are keys to the functioning of the clock. CRY protein levels are dependent upon their timely degradation by F-box proteins. This has recently been shown in the afterhours (Afh) mutant carrying a mutation in the F -box gene, Fbxl3. Afh has been shown to lengthen circadian period by stabilising levels of CRY proteins across the circadian cycle. To understand the specific roles of each of the two CRY proteins in circadian regulation, we generated compound mouse mutants to investigate the behavioural and molecular consequences of stabilising either CRY1 or CRY2 protein levels in mice lacking the alternative form of Cry. The circadian wheel-running activity assessed in light:dark and constant environmental conditions for both Cryrl-;FbxI3Afh/Afh and Cry[I-;FbxI3Afh/Afh (stabilising CRY2 and CRY1 protein levels respectively); clearly show a gradual increase in period length in constant darkness as the dosage of Fbxl3Afh is increased. This would suggest that stabilisation of either CRY protein can lengthen the clock, presumably as a result of a prolonged phase of transcriptional repression by either protein. This effect seen in the compound mutants was confirmed at the gene and protein levels.EThOS - Electronic Theses Online ServiceGBUnited Kingdo