Project description:We introduce APEX-seq, a method for RNA sequencing based on direct proximity labeling of RNA using the peroxidase enzyme APEX2. APEX-seq in nine distinct subcellular locales produced a nanometer-resolution spatial map of the human transcriptome as a resource, revealing extensive patterns of localization for diverse RNA classes and transcript isoforms. We uncover a radial organization of the nuclear transcriptome, which is gated at the inner surface of the nuclear pore for cytoplasmic export of processed transcripts. We identify two distinct pathways of messenger RNA localization to mitochondria, each associated with specific sets of transcripts for building complementary macromolecular machines within the organelle. APEX-seq should be widely applicable to many systems, enabling comprehensive investigations of the spatial transcriptome.
Project description:The distribution of RNA in human embryonic stem cells (hESC) and the function of RNA localization in maintaining hESC pluripotency and differentiation are currently unknown. Here, by isolating five subcellular components of hESCs and differentiated cells, we uncovered the global subcellular RNA localization in hESC. For protein-coding mRNA, different transcripts of the same gene exhibit an “isoform switch” between subcellular components, which is regulated by localization cis-elements in their variable regions. For noncoding RNA, multiple sequence features such as polyA tail, length, and GC content jointly regulate their subcellular localization. In addition, we found that some developmental genes can be transcribed in advance and confined to chromatin in undifferentiated hESCs. Finally, we revealed significant changes in overall RNA distribution, mapped RNA dynamic localization atlas, and characterized different dynamic RNA localization patterns during hESC differentiation into mesoderm. The multiple RNA localization patterns we revealed will provide some new enlightenment for hESC stemness maintenance and differentiation.
Project description:An integrating APEX proximity labeling and chemical cross-linking coupled with mass spectrometry (CXMS) platform named APEX-CXMS for spatially resolved subcellular interactome profiling in a high-throughput ma
Project description:We present MERR APEX-seq, a method for newly transcribed RNAs subcellular profiling combined metabolic incorporation of electron-rich ribonucleosides, 6-thioguanosine and 4-thiouridine, with the peroxidase-mediated RNA labeling method, APEX-seq. MERR APEX-seq offers both high spatial specificity and high coverage in the mitochondrial matrix and at the endoplasmic reticulum membrane. Application of MERR APEX-seq at nuclear lamina of human cells reveals that the mRNA components tend to encode for transcripts processing related proteins. MERR APEX-seq with high spatial specificity and high coverage could be widely used to expand our knowledge of RNA localization and function at subcellular compartments.
Project description:Subcellular organization of RNAs and proteins is critical for cell function, but we still lack global maps and conceptual frameworks for how these molecules are localized in cells and tissues. Here we introduce ATLAS-Seq, which generates transcriptomes and proteomes from detergent-free tissue lysates fractionated across a sucrose gradient. Proteomic analysis of fractions confirmed separation of subcellular compartments. Unexpectedly, RNAs tended to co-sediment with other RNAs in similar protein complexes, cellular compartments, or biological functions. With the exception of those encoding secreted proteins, most RNAs sedimented differently than their encoded protein counterparts. To identify RNA binding proteins potentially driving these patterns, we correlated their sedimentation profiles to all RNAs, confirming known interactions and predicting new associations. Hundreds of alternative RNA isoforms exhibited distinct sedimentation patterns across the gradient, despite sharing most of their coding sequence. These observations suggest that transcriptomes can be organized into networks of co-segregating mRNAs encoding functionally related proteins, and provide insights into the establishment and maintenance of subcellular organization.
Project description:In the preimplantation mouse embryo TEAD4 is critical to establishing the trophectoderm (TE)-specific transcriptional program and segregating TE from the inner cell mass (ICM). However, TEAD4 is expressed both in the TE and the ICM. Thus, differential function of TEAD4 rather than expression itself regulates specification of the first two cell lineages. We used ChIP-seq to define genome-wide TEAD4 target genes and asked how transcription of TEAD4 target genes is specifically maintained in the TE. Our analyses revealed an evolutionarily conserved mechanism, in which lack of nuclear localization of TEAD4 impairs the TE-specific transcriptional program in inner blastomeres, thereby allowing their maturation towards the ICM lineage. Restoration of TEAD4 nuclear localization maintains the TE-specific transcriptional program in the inner blastomeres and prevents segregation of the TE and ICM lineages and blastocyst formation. We propose that altered subcellular localization of TEAD4 in blastomeres dictates first mammalian cell fate specification. ChIPseq profiles of TEAD4, IgG, Input in Mouse trophoblast stem cells using Illumina HiSeq 2000 and Illumina Genome Analyzer IIx
Project description:Objective: To assess the role of aldoketoreductases and other doxorubicin pharmacokinetic or pharmacogenomic genes in doxorubicin cytotoxicity, resistance, DNA binding activity, and subcellular localization, Methods: We conducted a whole genome microarray study to identify differences in between doxorubicin-sensitive MCF-7cc cells and doxorubicin-resistant MCF-7Dox2-12 cells in terms of their expression of genes related to doxorubicin pharmacokinetics or pharmacodynamics. Targets were then validated by pharmacologic inhibition in conjunction with drug metabolite profiling, drug localization, drug cytotoxicity, and drug DNA binding studies. Results: 2063 differentially expressed transcripts were identified, including 17% and 43% of genes or gene families associated with doxorubicin pharmacokinetics or pharmacodynamics (p values of significance of 0.05 and <0.0001, respectively). The largest changes in the expression of genes associated with doxorubicin pharmacokinetics and pharmacodynamics were chiefly among the aldo-keto reductases (AKRs) Akr1c2, Akr1c3 and Akr1b10 which convert doxorubicin to doxorubicinol. We observed that doxorubicinol exhibits dramatically reduced drug toxicity, reduced drug DNA-binding activity, and altered drug subcellular localization to lysosomes. Pharmacologic inhibition of these AKRs in MCF-7Dox2-12 cells restored drug cytotoxicity, and drug localization to the nucleus. Conclusion: These findings demonstrate the utility of using curated pharmacokinetic and pharmacodynamic knowledgebases to identify highly relevant genes associated with doxorubicin resistance. The products of one or more of these genes could effectively be shown to alter the drug’s properties, while inhibiting them restored drug DNA binding, cytotoxicity, and subcellular localization. Doxorubicin resistant cell lines of breast MCF-7 cells were generated for gene expression profilling. Two colour microarray of Agilent whole human genome nucleotide arrays was conducted with four labelling replicates of both forward and reverse labellings plus another set of 8 arrays with forward labelling. Sixteen arrays were used for this experiments. The co-cultured control cells MCF-7cc12 was generated by parallel selection process in the absence of drug.