Transcriptome-wide RNA structure probing reveals the structural basis of Dicer binding and cleavage
Ontology highlight
ABSTRACT: RNA structure is vital for its function. Current transcriptome-wide RNA structure probing methods only capture partial structure information. Measuring RNA structure in full length is critical to the function and regulation study of small RNAs and short fragments of functional sites. Here, we present icSHAPE-MaP, an approach combining in vivo click selective 2′-hydroxyl acylation and mutational profiling to probe intact RNA structures. We further showcase the RNA structural landscape of substrates bound by human Dicer, by combining RNA immunoprecipitation pull-down and small RNA structure profiling through icSHAPE-MaP. Structural categories of Dicer substrates were unveiled with distinct patterns in correlation to their binding affinity and cleavage efficiency. And by tertiary structural modeling for pre-miRNAs, one of the major binding and cleavage substrates for Dicer, we find the spatial distance measuring as an important parameter for Dicer cleavage-site selection.
Project description:we resolved precusor let7 (pre-let-7) and human Dicer-TRBP complex bound precusor let7 (hDicer-TRBP-pre-let-7) secondary structure based on in vivo click selective 2'-hydroxyl acylation and profiling experiment (icSHAPE). We found the free pre-let-7 RNA is more flexible comparing with hDicer-TRBP-pre-7 in the double strand region [10-20nt and 50- 60 nt].
Project description:Dicer plays a key role in small RNA biogenesis by processing double-stranded RNAs (dsRNAs). Human DICER (hDICER) is specialized in processing of small hairpins such as pre-microRNAs (pre-miRNAs) with a limited activity towards long dsRNAs, unlike its homologs in lower eukaryotes and plants which cleave long dsRNAs. While the mechanism of long dsRNA cleavage has been well documented, our understanding of pre-miRNA processing is limited due to lack of the structure of hDICER in a catalytic state. Here we report the cryo-electron microscopy structure of hDICER bound to pre-miRNA in a dicing state, uncovering the structural basis for pre-miRNA processing.
Project description:Dicer plays a key role in small RNA biogenesis by processing double-stranded RNAs (dsRNAs). Human DICER (hDICER) is specialized in processing of small hairpins such as pre-microRNAs (pre-miRNAs) with a limited activity towards long dsRNAs, unlike its homologs in lower eukaryotes and plants which cleave long dsRNAs. While the mechanism of long dsRNA cleavage has been well documented, our understanding of pre-miRNA processing is limited due to lack of the structure of hDICER in a catalytic state. Here we report the cryo-electron microscopy structure of hDICER bound to pre-miRNA in a dicing state, uncovering the structural basis for pre-miRNA processing.
Project description:Ribonuclease Dicer generates small RNAs for RNA interference (RNAi) and microRNA (miRNA) pathways. Mammalian Dicer produces miRNAs but its tripartite N-terminal helicase domain inhibits processing of double-stranded RNA for RNAi. Mouse oocytes express Dicer, which enhances RNAi because it lacks the helicase’s proximal subdomain HEL1. Here we show that genetic removal of HEL1 in mice causes embryonic growth retardation, defects in the cardiopulmonary system, and perinatal lethality. HEL1 suppresses biogenesis of mirtrons, a non-canonical low-abundant class of miRNAs, and is required for high-fidelity cleavage and strand selection during biogenesis of canonical miRNAs. Essential is the HEL1 structure, not its helicase activity, because mutations of critical aminoacids do not affect viability or fertility and have minimal impact on miRNA biogenesis. Altogether, HEL1 is a critical structural component of Dicer in its role of a highly conserved structural “mold” that ensures high-fidelity processing and adaptive evolution of mammalian miRNA precursors.
Project description:we resolved the RNA secondary structure of SARS-CoV-2 infected in Huh7.5.1 cells, in vitro structure of SARS-CoV-2 RNA purified from infected cells and refolded in test tube and viral RNA fragments of 7 coronaviruses including SARS-CoV-2, SARS-CoV and MERS-CoV based on in vivo click selective 2'-hydroxyl acylation and profiling experiment (icSHAPE). We built RNA structural model of SARS-CoV-2, found some functional structural elements, analysed the RNA structure conservation among different coronavirus. Also, we predicted RBP binding sites and identified some potential drug for CoVID-19 therapy.
Project description:we resolved the RNA secondary structure of human (HEK293, HeLa, K562, HepG2, H9) and mouse (mES) cells based on optimized in vivo click selective 2'-hydroxyl acylation and profiling experiment (icSHAPE). we describe a deep discriminative neural network (PrismNet) that integrates big data of RBP binding and RNA secondary structure from matched living cells and accurately models the RNA sequence and structural preferences of protein-RNA interactions in vivo, enabling precise prediction of the perturbation effects of genetic variants.
Project description:IRE1 is an unfolded protein response (UPR) sensor with kinase and endonuclease activity. It plays a central role in the endoplasmic reticulum (ER) stress response through unconventional splicing of XBP1 mRNA and regulated IRE1-dependent decay (RIDD), which cleaves RNA at an XBP1-like consensus sequence (CUGCAG) accompanied by a stem-loop structure. MM cells are known to exhibit an elevated level of baseline ER stress, but RIDD activity has not been well studied in this disease. To investigate novel RIDD targets of possible relevance to the survival/proliferation of MM cells we combined in vitro cleavage assay with RNA sequencing. Bioinformatic analysis revealed hundreds of putative IRE1 substrates, 32 of which were chosen for validation. Looking into the secondary structure of IRE1 substrates, we found that the consensus sequences of IRF4, PRDM1, IKZF1, KLF13, NOTCH1, ATR, DICER, RICTOR, CDK12, FAM168B, and CENPF mRNAs were accompanied by a stem-loop structure essential for IRE1-mediated cleavage. We show that mRNA and protein levels corresponding to these targets were attenuated in an IRE1-dependent manner by treatment with ER-stress-inducing agents. Our results demonstrate for the first time that IRE1 is a key regulator of several proteins of importance in MM survival and proliferation.
Project description:Visualizing the physical basis for molecular behavior inside living cells is a grand challenge in biology. RNAs are central to biological regulation, and RNA’s ability to adopt specific structures intimately controls every step of the gene expression program.1 However, our understanding of physiological RNA structures is limited; current in vivo RNA structure profiles predominantly viewed only two of four nucleotides that make up RNA.2,3 Here we present a novel biochemical approach, In Vivo Click SHAPE (icSHAPE), that enables the first global view of RNA secondary structures of all four bases in living cells. icSHAPE of embryonic stem cell transcriptome versus purified RNA folded in vitro shows that the structural dynamics of RNA in the cellular environment distinguishes different classes of RNAs and regulatory elements. Structural signatures at translational start sites and ribosome pause sites are conserved in vitro, suggesting that these RNA elements are programmed by sequence. In contrast, focal structural rearrangements in vivo reveal precise interfaces of RNA with RNA binding or modification proteins that are consistent with atomic-resolution structural data. Such dynamic structural footprints enable accurate prediction of RNA-protein interactions and N6-methyladenosine (m6A) modification genome-wide. These results open the door for structural genomics of RNA in living cells and reveal key physiological structures controlling gene expression.
Project description:Visualizing the physical basis for molecular behavior inside living cells is a grand challenge in biology. RNAs are central to biological regulation, and RNA’s ability to adopt specific structures intimately controls every step of the gene expression program.1 However, our understanding of physiological RNA structures is limited; current in vivo RNA structure profiles predominantly viewed only two of four nucleotides that make up RNA.2,3 Here we present a novel biochemical approach, In Vivo Click SHAPE (icSHAPE), that enables the first global view of RNA secondary structures of all four bases in living cells. icSHAPE of embryonic stem cell transcriptome versus purified RNA folded in vitro shows that the structural dynamics of RNA in the cellular environment distinguishes different classes of RNAs and regulatory elements. Structural signatures at translational start sites and ribosome pause sites are conserved in vitro, suggesting that these RNA elements are programmed by sequence. In contrast, focal structural rearrangements in vivo reveal precise interfaces of RNA with RNA binding or modification proteins that are consistent with atomic-resolution structural data. Such dynamic structural footprints enable accurate prediction of RNA-protein interactions and N6-methyladenosine (m6A) modification genome-wide. These results open the door for structural genomics of RNA in living cells and reveal key physiological structures controlling gene expression.