Circadian Regulation of ATP Release in Astrocytes

Abstract

Circadian clocks sustain daily oscillations in gene expression, physiology and behavior, relying on transcription-translation feedback loops of clock genes for rhythm generation. Cultured astrocytes display daily oscillations of extracellular ATP, suggesting that ATP release is a circadian output. We hypothesized that the circadian clock modulates ATP release via mechanisms that regulate acute ATP release from glia. To test the molecular basis for circadian ATP release, we developed methods to measure in real-time ATP release and Bmal1::dLuc circadian reporter expression in cortical astrocyte cultures from mice of different genotypes. Daily rhythms of gene expression required functional Clock and Bmal1, both Per1 and Per2, and both Cry1 and Cry2 genes. Similarly, high level, circadian ATP release also required a functional clock mechanism. Whereas blocking IP3 signaling significantly disrupted ATP rhythms with no effect on Bmal1::dLuc cycling, blocking vesicular release did not alter circadian ATP release or gene expression. We conclude that astrocytes depend on circadian clock genes and IP3 signaling to express daily rhythms in ATP release.

Adenosinergic Regulation of Striatal Clock Gene Expression and Ethanol Intake During Constant Light

“…Caffeine, an adenosine A1 receptor (A1R)/A2A receptor (A2AR) antagonist, lengthens (Oike et al, 2011), whereas ethanol shortens (Seggio et al, 2009), free-running (endogenous) circadian period. Circadian variation in astrocytic ATP release, extracellular adenosine concentration, and ENT1 and A1R expression has been reported in sleep/wake-promoting areas of the brain (Alanko et al, 2003;Marpegan et al, 2011;Murillo-Rodriguez et al, 2004;Virus et al, 1984). Together, this evidence suggests that adenosine may regulate cellular circadian timekeeping.…”

Forkhead Box O1 (FOXO1) Protein, but Not p53, Contributes to Robust Induction of p21 Expression in Fasted Mice

“…All images were initiated within 45 min of organ isolation. To allow for imaging multiple tissues from within one mouse, three low light imaging systems were utilized and kept consistent for each region: a Versarray back-thinned illuminated CCD camera (Princeton Instruments), and an iXon DU-897E EM CCD camera (Andor Technology), each coupled to TE-2000 Nikon inverted microscopes were equipped with custom light tight environmental chambers (InVivo Scientific) that prevented light leaks and allowed maintenance of a constant temperature of 37°C, or in a light tight box with an intensified CCD camera (XR/Mega-10Z; Stanford Photonics Inc.) (5). Image acquisition was controlled with Winview32 and Micro-Manager (www.Micro-Manager.org) software packages.…”

Astrocytic Adenosine 5′-Triphosphate Release Regulates the Proliferation of Neural Stem Cells in the Adult Hippocampus

“…Because IP 3 R2 is the only astrocyte-specific functional IP 3 receptor isoform [27,[29][30][31][32][33], we used IP 3 R2 À/À mice, which have been documented to be a valid tool for the study of the functional role of astrocytes in situ [29,33] to modulate ATP release from astrocytes in vivo. Previous data showed that the deletion of IP 3 R2 selectively disrupted the Gprotein-coupled receptor-dependent [Ca 2þ ] i responses in astrocytes [29,33].…”