Project description:The circadian clock drives daily changes of physiology, including sleep-wake cycles, by regulating transcription, protein abundance and function. Circadian phosphorylation controls cellular processes in peripheral organs, but little is known about its role in brain function and synaptic activity. We applied advanced quantitative phosphoproteomics to mouse forebrain synaptoneurosomes isolated across 24h, accurately quantifying almost 8,000 phosphopeptides. Remarkably, half of the synaptic phosphoproteins, including numerous kinases, had large-amplitude rhythms peaking at rest-activity and activity-rest transitions. Bioinformatic analyses revealed global temporal control of synaptic function via phosphorylation, including synaptic transmission, cytoskeleton reorganization and excitatory/inhibitory balance. Remarkably, sleep deprivation abolished 98% of all phosphorylation cycles in synaptoneurosomes, indicating that sleep-wake cycles rather than circadian signals are main drivers of synaptic phosphorylation, responding to both sleep and wake pressures.
Project description:The taxonomic relationship of Lentzea atacamensis and Lentzea deserti were re-evaluated using comparative genome analysis. The 16S rRNA gene sequence analysis indicated that the type strains of L. atacamensis and L. deserti shared 99.7% sequence similarity. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between the genomes of two type strains were 88.6% and 98.8%, respectively, greater than the two recognized thresholds values of 70% dDDH and 95-96% ANI for bacterial species delineation. These results suggested that L. atacamensis and L. deserti should share the same taxonomic position. And this conclusion was further supported by similar phenotypic and chemotaxonomic features between them. Therefore, we propose that L. deserti is a later heterotypic synonym of L. atacamensis.
Project description:Circadian rhythms are present across almost all species and affect several physiological and behavioral aspects of living organisms. The evolutionary advantage conferred by these rhythms could be their anticipatory properties. In the nervous system, anticipation is particularly interesting due to the spatiotemporal constraints derived by the highly compartmentalized neuronal structure. Previous work has confirmed that 900 genes are expressed in the mouse forebrain in robustly rhythmic fashion, and 180 transcripts are equally robustly circadian at the synapse. Interestingly, mRNAs are found in higher amounts at the end of the dark phase, and decrease exponentially during the first hours of light. This pattern resembles the “sawtooth” pattern of homeostatic sleep pressure. To further characterize this phenotype we propose to compare the synaptic transcriptome of sleep deprived mice to its control base line. This work would shed light into the emerging field of synaptic RNA transport and translation and its regulatory inputs. Hopefully, the results will yield to two different findings: the circadian and activity potential to regulate synaptic transport of RNA and the classification of transcripts deferentially regulated by both processes.
Project description:Loc1 RIP-chip Experimental procedure: C-terminally TAP-tagged Loc1p from yeast S. cerevisiae was purified from 1 L of cells grown in YPD medium as previously described (Gerber et al. 2004, PLoS Biol. 2, E79). Untagged control cells (BY4741) cells served as a negative control. cDNA was synthesized from 3 μg of total RNA derived from the extract and 500 ng of affinity-isolated RNA and labeled with Cy3 and Cy5 fluorescent dyes, respectively. Samples were mixed and hybridized to cDNA microarrays. Publication: Niedner-Boblenz A. et al. 2024, Nucleic Acids Res, in press. Title: Intrinsically disordered RNA-binding motifs cooperate to catalyze RNA folding and drive phase separation Abstract: RNA-binding proteins are essential for gene regulation and the spatial organization of cells. Here, we report that the yeast ribosome biogenesis factor Loc1p is an intrinsically disordered RNA-binding protein with eight repeating positively charged, unstructured nucleic acid binding (PUN) motifs. While a single of these previously undefined motifs stabilizes folded RNAs, multiple copies strongly cooperate to catalyze RNA folding. In the presence of RNA, these multivalent PUN motifs drive phase separation. Proteome-wide searches in pro- and eukaryotes for proteins with similar arrays of PUN motifs reveal a strong enrichment in RNA-mediated processes and DNA remodeling. Thus, PUN motifs are potentially involved in a large variety of RNA- and DNA-related processes by concentrating them in membrane-less organelles. The general function and wide distribution of PUN motifs across species suggests that in an ancient “RNA world” PUN-like motifs may have supported the correct folding of early ribozymes.
Project description:Alignment of fasting and feeding with the sleep/wake cycle is coordinated by hypothalamic neurons, though the underlying molecular programs remain incompletely understood. Here we demonstrate that the clock transcription pathway maximizes eating during wakefulness and glucose production during sleep through transcription pathway maximizes eating during autonomous circadian regulation of NPY/AgRP neurons. Tandem profiling of whole cell and ribosome-bound mRNAs in morning and evening under dynamic fasting and fed conditions identified temporal control of activity-dependent gene repertoires in AgRP neurons central to synaptogenesis, bioenergetics, and neurotransmitter and peptidergic signaling. Synaptic and circadian pathways were specific to whole cell RNA analyses, while bioenergetic pathways were selectively enriched in the ribosome-bound transcriptome. Finally, we demonstrate that the AgRP clock mediates the transcriptional food acquisition with sleep/wake state. response to leptin. Our results reveal that time-of-day restriction in transcriptional control of energy-sensing neurons underlies the alignment of hunger and day restriction in transcriptional control of energy-sensing neurons underlies the alignment of hunger and food acquisition with sleep/wake state.
Project description:Purpose: To determine the specific effects of 6 hours sleep deprivation after a learning event on the transcriptomes of microglia. Sleep deprivation can generate inflammatory responses in the neuronal environment. In turn, this inflammation increases sleep drive, leading to a rebound in sleep duration. Microglia, a type of support cell found exclusively in the brain, have previously been found to release of inflammatory signals and exhibit altered characteristics in response to sleep deprivation. Together, this suggests microglia may be partially responsible for the brain’s response to sleep deprivation through their inflammatory activity. In this study, we fully and selectively ablated microglia from the mouse brain and assessed resulting sleep, circadian, and sleep deprivation phenotypes. We find microglia are dispensable for both homeostatic sleep and circadian function and the sleep rebound response to sleep deprivation. However, we uncover a phenomenon by which microglia appear to be essential for the protection of synapses and associated memories formed during a period of sleep deprivation, further expanding the list of known functions for microglia in synaptic modulation.
Project description:Comparative genomic hybridization experiments comparing DNA from experimentally evolved yeast strains to DNA from a euploid control.