Project description:Systems biological approaches to study the Arabidopsis thaliana circadian clock have mainly focused on transcriptomics while little is known about the proteome, and even less about post-translational modifications. Evidence has emerged that post-translational protein modifications, in particular phosphorylation, play an important role for the clock and its output. Phosphoproteomics is the method of choice for a large scale approach to gain more knowledge about rhythmic protein phosphorylation. Recent plant phosphoproteomics publications have identified several thousand phosphopeptides. However, the methods used in these studies are very labour-intensive and therefore not suitable to apply to a well-replicated circadian time series. To address this issue, we present and compare different strategies for sample preparation for phosphoproteomics that are compatible with large numbers of samples. Methods are compared regarding number of identifications, variability of quantitation and functional categorization. We focus on the type of detergent used for protein extraction as well as methods for its removal. We also test a simple two-fraction separation of the protein extract.
Project description:The molecular circadian clock, which controls rhythmic 24-hour oscillation of genes, proteins, and metabolites, is disrupted across many human cancers. Deregulated expression of MYC oncoprotein has been shown to alter expression of molecular clock genes, leading to a disruption of molecular clock oscillation across cancer types. However, it remained unclear how this loss of molecular clock oscillation impacted global gene expression and metabolism in cancer, and what benefit cancer cells might gain from suppressing clock oscillation. We hypothesized that MYC suppresses oscillation of gene expression and metabolism to instead upregulate pathways involved in biosynthesis in a static, non-oscillatory fashion. To test this, we utilized cells from distinct cancer types with inducible MYC or the closely related N-MYC to determine, using detailed time-series RNA-sequencing and metabolomics, the extent to which MYC activation disrupts global oscillation of genes, gene expression, programs, and metabolites. We focused our analyses on genes, pathways, and metabolites that changed in common across multiple cancer cell line models. We report here that MYC disrupted over 85% of oscillating genes, while instead promoting enhanced ribosomal and mitochondrial biogenesis and suppressed cell attachment pathways. Notably, when MYC is activated, biosynthetic programs that were formerly circadian flipped to being upregulated in an oscillation-free manner. Further, activation of MYC ablates the oscillation of nutrient transporter glycosylation while greatly upregulating transporter expression, cell surface localization, and intracellular amino acid pools. Finally, we report that MYC disrupts metabolite oscillations and the temporal segregation of amino acid metabolism from nucleotide metabolism. Our results demonstrate that MYC disruption of the molecular circadian clock releases metabolic and biosynthetic processes from circadian control, which may provide a distinct advantage to cancer cells.
Project description:The molecular circadian clock, which controls rhythmic 24-hour oscillation of genes, proteins, and metabolites, is disrupted across many human cancers. Deregulated expression of MYC oncoprotein has been shown to alter expression of molecular clock genes, leading to a disruption of molecular clock oscillation across cancer types. It remains unclear what benefit cancer cells gain from suppressing clock oscillation, and how this loss of molecular clock oscillation impacts global gene expression and metabolism in cancer. We hypothesized that MYC suppresses oscillation of gene expression and metabolism to instead upregulate pathways involved in biosynthesis in a static, non-oscillatory fashion. To test this, cells from distinct cancer types with inducible MYC or the closely related N-MYC were examined, using detailed time-series RNA-sequencing and metabolomics, to determine the extent to which MYC activation disrupts global oscillation of genes, gene expression, programs, and metabolites. We focused our analyses on genes, pathways, and metabolites that changed in common across multiple cancer cell line models. We report here that MYC disrupted over 85% of oscillating genes, while instead promoting enhanced ribosomal and mitochondrial biogenesis and suppressed cell attachment pathways. Notably, when MYC is activated, biosynthetic programs that were formerly circadian flipped to being upregulated in an oscillation-free manner. Further, activation of MYC ablates the oscillation of nutrient transporter proteins while greatly upregulating transporter expression, cell surface localization, and intracellular amino acid pools. Finally, we report that MYC disrupts metabolite oscillations and the temporal segregation of amino acid metabolism from nucleotide metabolism. Our results demonstrate that MYC disruption of the molecular circadian clock releases metabolic and biosynthetic processes from circadian control, which may provide a distinct advantage to cancer cells.
Project description:The molecular circadian clock, which controls rhythmic 24-hour oscillation of genes, proteins, and metabolites, is disrupted across many human cancers. Deregulated expression of MYC oncoprotein has been shown to alter expression of molecular clock genes, leading to a disruption of molecular clock oscillation across cancer types. However, it remained unclear how this loss of molecular clock oscillation impacted global gene expression and metabolism in cancer, and what benefit cancer cells might gain from suppressing clock oscillation. We hypothesized that MYC suppresses oscillation of gene expression and metabolism to instead upregulate pathways involved in biosynthesis in a static, non-oscillatory fashion. To test this, we utilized cells from distinct cancer types with inducible MYC or the closely related N-MYC to determine, using detailed time-series RNA-sequencing and metabolomics, the extent to which MYC activation disrupts global oscillation of genes, gene expression, programs, and metabolites. We focused our analyses on genes, pathways, and metabolites that changed in common across multiple cancer cell line models. We report here that MYC disrupted over 85% of oscillating genes, while instead promoting enhanced ribosomal and mitochondrial biogenesis and suppressed cell attachment pathways. Notably, when MYC is activated, biosynthetic programs that were formerly circadian flipped to being upregulated in an oscillation-free manner. Further, activation of MYC ablates the oscillation of nutrient transporter glycosylation while greatly upregulating transporter expression, cell surface localization, and intracellular amino acid pools. Finally, we report that MYC disrupts metabolite oscillations and the temporal segregation of amino acid metabolism from nucleotide metabolism. Our results demonstrate that MYC disruption of the molecular circadian clock releases metabolic and biosynthetic processes from circadian control, which may provide a distinct advantage to cancer cells.
Project description:Meal timing is essential in synchronization of circadian rhythms in different organ systems through clock-dependent and -independent mechanisms. The liver is a critical metabolic organ whose circadian clock and transcriptome can be readily reset by meal timing. However, it remains largely unexplored how circadian rhythms in the liver are organized in time-restricted feeding that intervenes meal timing. Here, we applied data-independent acquisition proteomics to characterize circadian features associated with day/sleep- (DRF) and night/wake (NRF)-time restricted feeding in nocturnal female mice. The transcriptomics and metabolomics datasets are public (see www.circametdb.org.cn).