Université de Fribourg

Changing the light schedule in late pregnancy alters birth timing in mice

Amano, Tomoko ; Ripperger, Jürgen A. ; Albrecht, Urs

In: Theriogenology, 2020, vol. 154, p. 212–222

In rats, birth timing is affected by changes in the light schedule until the middle of the pregnancy period. This phenomenon can be used to control birth timing in the animal industry and/or clinical fields. However, changes in the light schedule until the middle of the pregnancy period can damage the fetus by affecting the development of the major organs. Thus, we compared birth timing in...

Université de Fribourg

Cyclin-dependent kinase 5 (CDK5) regulates the circadian clock

Brenna, Andrea ; Olejniczak, Iwona ; Chavan, Rohit ; Ripperger, Jürgen A. ; Langmesser, Sonja ; Cameroni, Elisabetta ; Hu, Zehan ; De Virgilio, Claudio ; Dengjel, Jörn ; Albrecht, Urs

In: eLife, 2019, vol. 8, p. e50925

Circadian oscillations emerge from transcriptional and post-translational feedback loops. An important step in generating rhythmicity is the translocation of clock components into the nucleus, which is regulated in many cases by kinases. In mammals, the kinase promoting the nuclear import of the key clock component Period 2 (PER2) is unknown. Here, we show that the cyclin-dependent kinase 5...

Université de Fribourg

Circadian clocks and sleep: impact of rhythmic metabolism and waste clearance on the brain

Albrecht, Urs ; Ripperger, Jürgen A.

In: Trends in Neurosciences, 2018, vol. 41, no. 10, p. 677–688

The rotation of the Earth around its axis causes periodic exposure of half of its surface to sunlight. This daily recurring event has been internalized in most organisms in the form of cellular circadian clock mechanisms. These cellular clocks are synchronized with each other in various ways to establish circadian networks that build the circadian program in tissues and organs, coordinating...

Université de Fribourg

Circadian control of DRP1 activity regulates mitochondrial dynamics and bioenergetics

Schmitt, Karen ; Grimm, Amandine ; Dallmann, Robert ; Oettinghaus, Bjoern ; Restelli, Lisa Michelle ; Witzig, Melissa ; Ishihara, Naotada ; Mihara, Katsuyoshi ; Ripperger, Jürgen A. ; Albrecht, Urs ; Frank, Stephan ; Brown, Steven A. ; Eckert, Anne

In: Cell Metabolism, 2018, vol. 27, no. 3, p. 657-666.e5

Mitochondrial fission-fusion dynamics and mitochondrial bioenergetics, including oxidative phosphorylation and generation of ATP, are strongly clock controlled. Here we show that these circadian oscillations depend on circadian modification of dynamin-related protein 1 (DRP1), a key mediator of mitochondrial fission. We used a combination of in vitro and in vivo models, including human skin...

Université de Fribourg

REV-ERBα regulates Fgf21 expression in the liver via hepatic nuclear factor 6

Chavan, Rohit ; Preitner, Nadia ; Okabe, Takashi ; Mansencal Strittmatter, Laureen ; Xu, Cheng ; Ripperger, Jürgen A. ; Pitteloud, Nelly ; Albrecht, Urs

In: Biology Open, 2017, vol. 6, no. 1, p. 1–7

The circadian clock contributes to the timing of many body functions including metabolism and reproduction. The hepatokine fibroblast growth factor 21 (FGF21) is a critical metabolic regulator involved in modulation of fertility. Here we show that lack of the clock component REV-ERBα elevates FGF21 levels in liver and plasma. At the molecular level, REV-ERBα modulates the expression of...

Université de Fribourg

Rev‐erbα modulates the hypothalamic orexinergic system to influence pleasurable feeding behaviour in mice

Feillet, Céline A. ; Bainier, Claire ; Mateo, Maria ; Blancas-Velázquez, Aurea ; Salaberry, Nora L. ; Ripperger, Jürgen A. ; Albrecht, Urs ; Mendoza, Jorge

In: Addiction Biology, 2017, vol. 22, no. 2, p. 411–422

The drive to eat is regulated by two compensatory brain pathways termed as homeostatic and hedonic. Hypothalamic orexinergic (ORX) neurons regulate metabolism, feeding and reward, thus controlling physiological and hedonic appetite. Circadian regulation of feeding, metabolism and rhythmic activity of ORX cells are driven by the brain suprachiasmatic clock. How the circadian clock impacts on...

Université de Fribourg

Normalisation against circadian and age-related disturbances enables robust detection of gene expression changes in liver of aged mice

Costa, Sara S. Fonseca ; Wegmann, Daniel ; Ripperger, Jürgen A.

In: PLOS ONE, 2017, vol. 12, no. 1, p. e0169615

The expression of some genes is affected by age. To detect such age-related changes, their expression levels are related to constant marker genes. However, transcriptional noise increasing with advancing age renders difficult the identification of real age-related changes because it may affect the marker genes as well. Here, we report a selection procedure for genes appropriate to normalise...

Université de Fribourg

Reciprocal regulation of carbon monoxide metabolism and the circadian clock

Klemz, Roman ; Reischl, Silke ; Wallach, Thomas ; Witte, Nicole ; Jürchott, Karsten ; Klemz, Sabrina ; Lang, Veronika ; Lorenzen, Stephan ; Knauer, Miriam ; Heidenreich, Steffi ; Xu, Min ; Ripperger, Jürgen A. ; Schupp, Michael ; Stanewsky, Ralf ; Kramer, Achim

In: Nature Structural & Molecular Biology, 2017, vol. 24, no. 1, p. 15-22

Circadian clocks are cell-autonomous oscillators regulating daily rhythms in a wide range of physiological, metabolic and behavioral processes. Feedback of metabolic signals, such as redox state, NAD+/NADH and AMP/ADP ratios, or heme, modulate circadian rhythms and thereby optimize energy utilization across the 24-h cycle. We show that rhythmic heme degradation, which generates the signaling...

Université de Fribourg

REV-ERBα influences the stability and nuclear localization of the glucocorticoid receptor

Okabe, Takashi ; Chavan, Rohit ; Costa, Sara S. Fonseca ; Brenna, Andrea ; Ripperger, Jürgen A. ; Albrecht, Urs

In: Journal of Cell Science, 2016, vol. 129, no. 21, p. 4143–4154

REV-ERBα (encoded by Nr1d1) is a nuclear receptor that is part of the circadian clock mechanism and regulates metabolism and inflammatory processes. The glucocorticoid receptor (GR, encoded by Nr3c1) influences similar processes, but is not part of the circadian clock, although glucocorticoid signaling affects resetting of the circadian clock in peripheral tissues. Because of their similar...