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METACLOCK Report Summary

Project ID: 281348
Funded under: FP7-IDEAS-ERC
Country: United Kingdom

Final Report Summary - METACLOCK (Metabolic oscillations and the 24 hour (circadian) clockwork)

We live in a world dominated by a “24 hour” mentality, with transatlantic air travel and shift-work being part of normal life for many people. These types of desynchronisations (e.g. “jet-lag” and shift-work) disrupt our daily physiology and are increasingly being linked to diseases such as diabetes, obesity and cancer. Clock disruption is thus widespread in modern society.

We know that every cell in the body has its own molecular clock, allowing it to coordinate its daily activities accurately, just as we would use a clock in our daily lives. At the start of the project we had recently discovered novel mechanisms about how the molecular clock works, centred around chemical oxidation and reduction reactions within proteins called peroxiredoxins.

We first characterised peroxiredoxin protein oscillations in a variety of clock model systems across phylogenetic kingdoms to see whether these oscillations are conserved. Our preliminary data suggested that post-translational redox oscillations of these proteins are shared between eukaryotic algae and humans, which evolved 1,000M years apart. We thus extended this and postulated that these oscillations may exist in any form of life, since they are expressed in virtually all known organisms. We tested this using samples from wild-type and “clock mutant” organisms (cyanobacteria, fungi, plants, flies and mammals) and related this to the known transcriptional clockwork in these organisms. This lead to a significant publication in the journal Nature.

Our second objective was to characterise metabolic (non-transcriptional) circadian oscillations in the cytoplasm and mitochondrion of mammalian cells. The experiments were challenging but we made good progress over the project to achieve real-time cell imaging of cells expressing fluorescent sensors that could report basic changes in the cell’s state (e.g. redox balance, cell cycle stage). Some elements of this work were recently published as part of a paper in the journal Proceedings of the National Academy of Sciences (PNAS).

The third objective was to characterise the metabolite profiles (metabolome) of mammalian cells and tissue using various methods including mass spectrometry and nuclear magnetic resonance spectroscopy (NMR). By determining the metabolite levels in core glucose-metabolising pathways (glycolysis and the pentose phosphate pathway), we were able to achieve an in depth view of the complex inter-relationships between different metabolic pathways (and the pentose phosphate pathway in particular) within the cells and the transcriptional networks governing the clockwork over the 24 hour cycle. A gene called NRF2, important in redox signalling to transcriptional networks, was found to be a key node linking redox pathways and transcriptional oscillations. This work was published recently in Cell Metabolism, a leading metabolism journal.

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United Kingdom
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