Project description:In eukaryotes, RNA is synthesized in the nucleus, spliced, and exported to the cytoplasm where it is translated and finally degraded. Any of these steps could be subject to temporal regulation during the circadian cycle, generating daily fluctuations of RNA accumulation and impacting the distribution of transcripts in different subcellular compartments. Here, we performed a comprehensive analysis of nuclear and cytoplasmic, polyA and total, transcriptomes of mouse livers sampled along the daily cycle. These data provide a genome-wide temporal inventory of RNA subcellular enrichments, and revealed specific signatures of splicing, nuclear export and cytoplasmic mRNA stability related to transcript and gene lengths. Combined with a mathematical model describing rhythmic RNA profiles , we could test the rhyhtmicity of export rates and cytoplasmic degradation rates of ~1400 genes. While nuclear export times are usually much shorter than cytoplasmic half-lives, we found that that nuclear export contributes to the modulation and generation of rhythmic profiles of ~10% of the cycling nuclear mRNAs. This study provides an estimation of the nuclear and cytoplasmic life times in the liver and contributes to a better understanding of the dynamic regulation of the transcriptome during the feeding-fasting cycle.
Project description:Dynamic change in subcellular localization of signaling proteins is a general concept that eukaryotic cells evolved for responding and elicit a coordinated response to stimuli. Mass spectrometry (MS)-based proteomics in combination with subcellular fractionation can provide comprehensive maps of spatio-temporal regulation of cells but this is highly challenging involving laborious workflows that do not cover the phosphoproteome level. Here we present a high-throughput workflow based on sequential cell fractionation to profile the global (phospho)proteome dynamics across six distinct subcellular fractions. We benchmarked the workflow by studying spatio-temporal EGFR phospho-signaling dynamics in-vitro in HeLa cells and in-vivo in mouse tissues. Finally, we investigated the spatio-temporal stress signaling, revealing cellular relocation of ribosomal proteins in response to hypertonicity and muscle contraction.
Project description:To determine the downstream regulatory network of HNF4A and HNF1A, two transcription factors that play important roles in the pancreas and liver and that are associated with diabetes, we generated a comprehensive genome-wide map of the binding targets of HNF4A and HNF1A in hiPSC-derived pancreatic and hepatic cells and relevant cell lines using ChIP-Seq and molecular validation. We report binding targets of HNF4A and HNF1A that map to both known and novel gene promoters, that are common or differentially bound across different cell types and developmental stages. Overall, the detailed characterisation of the regulatory roles of HNF4A and HNF1A in pancreatic beta cells and hepatic cells will potentially shed light on how dysregulation of these factors can contribute to altered tissue development and function, and thus pathogenesis of both monogenic diabetes and T2D.
Project description:Prospective study of accuracy of colonic polyp characterisation in vivo using high resolution white light endoscopy, narrow band imaging and chromoendoscopy.
Project description:Existing methods to analyse RNA localisation are constrained to specific RNAs or subcellular niches, precluding the cell-wide mapping of RNA. We present Localisation of RNA (LoRNA), which maps, at once, RNAs to membranous (nucleus, ER and mitochondria) and membraneless compartments (cytosol, nucleolus and phase-separated granules). Simultaneous interrogation of all RNA locations allows the system-wide quantification of RNA proportional distribution and the comprehensive analysis of RNA subcellular dynamics. Moreover, we have re-engineered the LOPIT (Localisation Of Proteins by Isotope Tagging) method, enabling integration with LoRNA, to jointly map RNA and protein subcellular localisation. Applying this framework, we obtain a global re-localisation map for 31839 transcripts and 5314 proteins during the unfolded protein response, uncovering that ER-localised transcripts are more efficiently recruited to stress granules than cytosolic RNAs, and revealing eIF3d is key to sustain cytoskeletal function. Overall, we provide the most exhaustive map to date of RNA and protein subcellular dynamics.