Controlling circadian behavior in mice

Controlling circadian behavior in mice

The mammalian circadian clock is coordinated by the brain’s suprachiasmatic nucleus (SCN) and involves self-sustaining transcriptional–translational negative feedback loops (TTFLs) in which CLOCK and BMAL1 proteins drive expression of the negative regulator proteins Period and Cryptochrome (Cry). Globally deleting the genes for Cry1 and Cry2 disables the TTFL and disrupts circadian rhythms.
 
The researchers developed a translational switch based on genetic code expansion (GCE) that involved incorporating a noncanonical amino acid (ncAA) into Cry1, resulting in Cry1 translation and ncAA-dependent expression.
 
The authors found that ncAA-dependent activation of Cry1 translation in neurons of arrhythmic Cry-deficient SCN slices reversibly and dose-dependently initiated TTFL molecular rhythms. Using the ncAA to activate Cry1 translation in SCN neurons of arrhythmic Cry1- and Cry2-null mice rapidly and reversibly initiated circadian behavior, and the amplitude of the circadian rhythm was dependent on the number of transduced SCN neurons.
 
The results indicate that expression of Cry1 in SCN neurons is sufficient to initiate and sustain TTFLs and circadian timekeeping. The authors suggest that GCE-based translational switching might be used to reversibly control diverse mammalian behaviors.
 
http://www.pnas.org/content/early/2018/11/27/1811438115
 
http://sciencemission.com/site/index.php?page=news&type=view&id=publications%2Frapid-functional&filter=22

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