Splicing Shifts - How the circadian clock senses and buffers temperature changes

11th May 2012

A new paper published recently in Plant Cell has demonstrated that alternative splicing is an important additional mechanism in the regulation of the circadian clock in Arabidopsis particularly in response to low temperatures.

The paper by the laboratories of Professor John Brown of the University of Dundee Division of Plant Sciences based at the James Hutton Institute and Professor Hugh Nimmo of the University of Glasgow was featured as Editor’s Choice in Science Magazine on 13 April.

Their research shows specific core clock genes undergo temperature-dependent alternative splicing to reduce the levels of functional mRNAs and protein in response to temperature changes.

Circadian rhythms are ubiquitous in nature with organisms exhibiting daily rhythms in biological processes, growth or behaviour. We are all familiar with our sleep/wake cycle which is set to local time and gives rise to jet lag when we move to new time-zones.

Rhythms are driven by 'circadian clocks' located in every living cell that continue to run even in the absence of external signals. The clocks contain a set of interlocked transcriptional feedback loops with imposed delays that generate a characteristic ~24h rhythm.

Circadian clocks allow organisms to anticipate predictable environmental changes such as the regular day to night transitions and to optimise the timing of key pathways (for example, metabolic, signalling, growth and development) through the day.

In plants, the clock is regulated by light and temperature reflecting the changing daily and seasonal conditions. In turn, it regulates over a third of genes and processes such as photosynthesis, leaf movement, flower opening, growth etc. and is important in regulating flowering time in barley and dormancy in potato.

Clocks are able to operate and maintain their oscillations in a range of temperatures which is particularly important for plants that are exposed to ever-changing environments. The research from the Brown/Nimmo labs opens a new avenue for investigating how the clock senses and buffers temperature changes.

Paper referred to: Alternative Splicing Mediates Responses of the Arabidopsis Circadian Clock to Temperature Changes, Plant Cell 24, 961-981. (doi: 10.1105/tpc.111.093948)

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