Most organisms from bacteria to humans exhibit 24-hours rhythms in their biochemistry, physiology and behavior. Best exemplified by the sleep/wake cycle, these rhythms are remarkably widespread and include in humans hormonal (e.g., melatonin, insulin, cortisol), metabolic (e.g., glucose, cholesterol), physiological and behavioral oscillations. In fact, most biological functions are rhythmic and are set to perform optimally at the most appropriate time of the day. For example, the human digestion process performs better during the day when we are supposed to eat.
These circadian rhythms are generated by "molecular clocks", which consist of a few "clock genes" interacting in feedback loops, and which drive the rhythmic expression of a large number of genes, i.e. ~10% of the transcriptome in any tissues. This wide impact of clock genes in regulating gene expression is underscored by the surprisingly large number of pathologies developed by clock-deficient mice. In addition to being arrhythmic, these mice indeed develop pathologies as diverse as mania-like behaviors, learning and memory defects, depression, drug addiction, insomnia, metabolic diseases, arthropathy, hematopoiesis defects and cancers.
Research in our lab aims at characterizing how circadian clocks and clock genes regulate gene expression to provide insights into how and why clock dysfuntion leads to a wide spectra of pathologies. To this end, we are using a wide-range of molecular and biochemical techniques to investigate the circadian clock function at the genome-wide level (e.g., next-generation sequencing). We are currently extending some of our recent results and focus on 1) how clock genes rhythmically regulate chromatin environment and 2) the mechanisms involved in rhythmic post-transcriptional regulation of gene expression.