Abstract
Nutrient-driven O-GlcNAcylation has been linked to epigenetic regulation of gene expression in metazoans. In C. elegans, O-GlcNAc marks the promoters of over 800 developmental, metabolic, and stress-related genes; these O-GlcNAc marked genes show a strong 5′, promoter-proximal bias in the distribution of RNA Polymerase II (Pol II). In response to starvation or feeding, the steady state distribution of O-GlcNAc at promoters remain nearly constant presumably due to dynamic cycling mediated by the transferase OGT-1 and the O-GlcNAcase OGA-1. However, in viable mutants lacking either of these enzymes of O-GlcNAc metabolism, the nutrient-responsive GlcNAcylation of promoters is dramatically altered. Blocked O-GlcNAc cycling leads to a striking nutrient-dependent accumulation of O-GlcNAc on RNA Pol II. O-GlcNAc cycling mutants also show an exaggerated, nutrient-responsive redistribution of promoter-proximal RNA Pol II isoforms and extensive transcriptional deregulation. Our findings suggest a complex interplay between the O-GlcNAc modification at promoters, the kinase-dependent “CTD-code,” and co-factors regulating RNA Pol II dynamics. Nutrient-responsive O-GlcNAc cycling may buffer the transcriptional apparatus from dramatic swings in nutrient availability by modulating promoter activity to meet metabolic and developmental needs.
Highlights
Animals have evolved under conditions of fluctuating nutrient availability, requiring them to adapt in order to balance growth and survival
Antibodies that recognize the O-GlcNAc epitope were used in chromatin immunoprecipitation (ChIP) experiments with synchronous, first larval stage (L1) wild type animals under starved and fed conditions [Experimental Procedures; [32]]
We have found that our Chromatin immunoprecipitation (ChIP)-chip data provided a less biased, hybridization-based signal across genes compared with new technology, such as ChIP-seq, and allows direct comparisons with previous work, including our own studies in Drosophila melanogaster [33] and C. elegans [32]
Summary
Animals have evolved under conditions of fluctuating nutrient availability, requiring them to adapt in order to balance growth and survival. Transcriptional regulation can occur at many different levels, including recruitment of RNA Polymerase II (Pol II) to the promoter and the transcription events of initiation, elongation, splicing, and termination All of these activities are influenced by the differential phosphorylation of the C-terminal domain (CTD) of Pol II [1] and its associated factors. RNA Pol II has been shown to be GlcNAcylated on the CTD [34,35,36], including on Ser and Ser-5 residues of the CTD heptad repeat [37,38,39], and the O-GlcNAcase (OGA) shown to be part of the Pol II elongation complex interacting with Pol II pausing factors [40] Much of this previous work has been performed in vitro using recombinant OGT and OGA and examining the impact of these activities on template-driven transcription of model reporter constructs. The post-translational modification of chromatinassociated substrates by nutrient responsive GlcNAcylation provides a direct link between the cellular metabolic state and Pol II promoter-proximal dynamics with epigenetic implications for the organism
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
