Université de Fribourg

Lack of Calbindin-D28k alters response of the murine circadian clock to light

Stadler, Frédéric ; Schmutz, Isabelle ; Schwaller, Beat ; Albrecht, Urs

In: Chronobiology International, 2010, vol. 27, no. 1, p. 68-82

A strong stimulus adjusting the circadian clock to the prevailing light-dark cycle is light. However, the circadian clock is reset by light only at specific times of the day. The mechanisms mediating such gating of light input to the CNS are not well understood. There is evidence that Ca²⁺ ions play an important role in intracellular signaling mechanisms, including signaling cascades...

Université de Fribourg

The mammalian circadian timing system: organization and coordination of central and peripheral clocks

Dibner, Charna ; Schibler, Ueli ; Albrecht, Urs

In: Annual Review of Physiology, 2010, vol. 72, p. 517-549

Most physiology and behavior of mammalian organisms follow daily oscillations. These rhythmic processes are governed by environmental cues (e.g., fluctuations in light intensity and temperature), an internal circadian timing system, and the interaction between this timekeeping system and environmental signals. In mammals, the circadian timekeeping system has a complex architecture, composed of a...

Université de Fribourg

Behavioural food-anticipation in clock genes deficient mice: confirming old phenotypes, describing new phenotypes

Mendoza, Jorge ; Albrecht, Urs ; Challet, Etienne

In: Genes, Brain and Behavior, 2010, vol. 9, p. -

Animals fed daily at the same time exhibit circadian food-anticipatory activity (FAA), which has been suggested to be driven by one or several food-entrainable oscillators (FEOs). FAA is altered in mice lacking some circadian genes essential for timekeeping in the main suprachiasmatic clock (SCN). Here we confirmed that single mutations of clock genes Per1−/− and...

Université de Fribourg

The mammalian clock component PERIOD2 coordinates circadian output by interaction with nuclear receptors

Schmutz, Isabelle ; Ripperger, Jürgen A. ; Baeriswyl-Aebischer, Stéphanie ; Albrecht, Urs

In: Genes & Development, 2010, vol. 24, p. 345-357

Mammalian circadian clocks provide a temporal framework to synchronize biological functions. To obtain robust rhythms with a periodicity of about a day, these clocks use molecular oscillators consisting of two interlocked feedback loops. The core loop generates rhythms by transcriptional repression via the Period (PER) and Cryptochrome (CRY) proteins, whereas the stabilizing loop establishes...

Université de Fribourg

Role of mutation of the circadian clock gene Per2 in cardiovascular circadian rhythms

Vukolic, Ana ; Antic, Vladan ; Vliet, Bruce N. Van ; Yang, Zhihong ; Albrecht, Urs ; Montani, Jean-Pierre

In: American Journal of Physiology Regulatory, Integrative and Comparative Physiolology, 2010, p. -

Alterations in the circadian blood pressure pattern are frequently observed in hypertension and lead to increased cardiovascular morbidity. However, there are no studies that have investigated a possible implication of the Period2 gene, a key component of the molecular circadian clock, on the circadian rhythms of blood pressure and heart rate. To address this question, we monitored blood...

Université de Fribourg

Age-dependent alterations in human PER2 levels after early morning blue light exposure

Jud, Corinne ; Chappuis, Sylvie ; Revell, Victoria L. ; Sletten, Tracey L. ; Saaltink, Dirk-Jan ; Cajochen, Christian ; Skene, Debra J. ; Albrecht, Urs

In: Chronobiology International, 2009, vol. 26, no. 7, p. 1462-1469

In our modern society, we are exposed to different artificial light sources that could potentially lead to disturbances of circadian rhythms and, hence, represent a risk for health and welfare. Investigating the acute impact of light on clock-gene expression may thus help us to better understand the mechanisms underlying disorders rooted in the circadian system. Here, we show an overall...

Université de Fribourg

cGMP-dependent protein kinase I, the circadian clock, sleep, and learning

Feil, Robert ; Hölter, Sabine M. ; Weindl, Karin ; Wurst, Wolfgang ; Langmesser, Sonja ; Gerling, Andrea ; Feil, Susanne ; Albrecht, Urs

In: Communicative & Integrative Biology, 2009, vol. 2, no. 4, p. 298 - 301

The second messenger cGMP controls cardiovascular and gastrointestinal homeostasis in mammals. However, its physiological relevance in the nervous system is poorly understood. Now, we have reported that the cGMP-dependent protein kinase type I (PRKG1) is implicated in the regulation of the timing and quality of sleep and wakefulness. Prkg1 mutant mice showed altered distribution of sleep and...

Université de Fribourg

cGMP-dependent protein kinase type I is implicated in the regulation of the timing and quality of sleep and wakefulness

Langmesser, Sonja ; Franken, Paul ; Feil, Susanne ; Emmenegger, Yann ; Albrecht, Urs ; Feil, Robert

In: PLoS ONE, 2009, vol. 4, no. 1, p. e4238

Many effects of nitric oxide (NO) are mediated by the activation of guanylyl cyclases and subsequent production of the second messenger cyclic guanosine-3′,5′-monophosphate (cGMP). cGMP activates cGMP-dependent protein kinases (PRKGs), which can therefore be considered downstream effectors of NO signaling. Since NO is thought to be involved in the regulation of both sleep and circadian...

Université de Fribourg

Period 2 regulates neural stem/progenitor cell proliferation in the adult hippocampus

Borgs, Laurence ; Beukelaers, Pierre ; Vandenbosch, Renaud ; Nguyen, Laurent ; Moonen, Gustave ; Maquet, Pierre ; Albrecht, Urs ; Belachew, Shibeshih ; Malgrange, Brigitte

In: BMC Neuroscience, 2009, vol. 10, p. 30

Background: Newborn granule neurons are generated from proliferating neural stem/progenitor cells and integrated into mature synaptic networks in the adult dentate gyrus of the hippocampus. Since light/dark variations of the mitotic index and DNA synthesis occur in many tissues, we wanted to unravel the role of the clock-controlled Period2 gene (mPer2) in timing cell cycle kinetics and...