Knockout Mouse in Circadian Rhythm Study

Scientists Discover a Faster and More Accurate Method of Studying the Circadian Rhythm

Nearly all animals that follow a 24-hour cycle are subject to the famous circadian rhythms – the physiological shifts that regulate our biology at a cellular level.

These inner biological clocks are affected by numerous genetic factors that have a strong impact on our behavior. Many of them are now easier to study and adjust thanks to advanced genetics and a brand new knockout rescue mouse designed to help researchers study the key elements and parts of the CRY1 protein responsible for regulating the length of the circadian period – at least in the case of mice.

A Whole New Method for Creating KO Mice

Published in Molecular Cell, the breakthroughs achieved by Professor Hiroki Ueda at the RIKEN Biology Center have been duly noted as revolutionary among many scientific circles worldwide. Professor Ueda, together with an expert team of researchers, has managed to create a new gene knockout mouse without the need to backcross or breed it.

The new technique was made possible with the help of KO stem cells. After the insertion of the rescue genes, the mouse’s behavior and response could easily be evaluated and studied in a single generation, as it grew up.

Since the circadian rhythms normally required a far more time-consuming and difficult course of action in the past, the new method of creating knockin and knockout mice is no longer as problematic. With the new genetically engineered mouse models, Professor Ueda’s group was far more easily able to study and understand the physiological functions regulated by environmental light that are most impacted by the 24-hour cycle.

How the New Technique Works

The new knockout rescue technique was adopted to help scientists understand proteins known as cryptochromes, which are closely associated with CRY1 functions.

The physiological roles adopted by cryptochromes are very different in animals when compared to plants. This comes despite the fact that the proteins are closely related to the circadian rhythms in both cases. To study them more closely in mammals, the CRY1 cryptochrome gene is crucial, however, its complete role still eludes scientists today.

Ueda and his team of researchers managed to identify at least ten areas that have a clear impact in affecting the circadian clock’s cycle in cultured cells. Using a mass spectrometry-based identification process, identifying and analyzing the gene’s specific sites, as well as its various mutations at each sites, became far more straightforward. The process was also accelerated by implementing 17 distinctive CRY1 mutation into separate mouse embryonic stem cells that came without the cryptochrome genes.

Results That Defy Expectation

The results showed that any of the mice that lacked these genes also lacked a circadian rhythm. However, as the scientists were able to reintroduce the CRY1 gene in the mice, it was possible to return the circadian rhythm, and the lengths of the restored periods depended on each specific mutation that the genes have undergone.

This find not only presents Dr. Ueda’s scientists with a significant amount of exciting data that will take some time to study, but also marks the first time that researchers were able to analyze the real time impact genetic intervention can have on the circadian rhythm, along with the CRY1 gene’s most fascinating uncharted qualities.