PRAS: Predicting functional targets of RNA binding proteins based on CLIP-seq peaks.

RNA-protein interaction plays important roles in post-transcriptional regulation. Recent advancements in cross-linking and immunoprecipitation followed by sequencing (CLIP-seq) technologies make it possible to detect the binding peaks of a given RNA binding protein (RBP) at transcriptome scale. However, it is still challenging to predict the functional consequences of RBP binding peaks. In this study, we propose the Protein-RNA Association Strength (PRAS), which integrates the intensities and positions of the binding peaks of RBPs for functional mRNA targets prediction. We illustrate the superiority of PRAS over existing approaches on predicting the functional targets of two related but divergent CELF (CUGBP, ELAV-like factor) RBPs in mouse brain and muscle. We also demonstrate the potential of PRAS for wide adoption by applying it to the enhanced CLIP-seq (eCLIP) datasets of 37 RNA decay related RBPs in two human cell lines. PRAS can be utilized to investigate any RBPs with available CLIP-seq peaks. PRAS is freely available at http://ouyanglab.jax.org/pras/

Detection and analysis of RNA methylation [version 1; peer review: 2 approved]

Our understanding of the expanded genetic alphabet has been growing rapidly over the last two decades, and many of these developments came more than 80 years after the original discovery of a modified guanine in tuberculosis DNA. These new understandings, leading to the field of epigenetics, have led to exciting new fundamental and applied knowledge and to the development of novel classes of drugs exploiting this new biology. The number of methyl modifications to RNA is about seven times greater than those found on DNA, and our ability to interrogate these enigmatic nucleobases has lagged significantly until recent years as an explosion in technologies and understanding has revealed the roles and regulation of RNA methylation in several fundamental and disease-associated biological processes. Here, we outline how the technology has evolved and which strategies are commonly used in the modern epitranscriptomics revolution and give a foundation in the understanding and application of the rich variety of these methods to novel biological questions

Monitored eCLIP: high accuracy mapping of RNA-protein interactions

International audienceCLIP-seq methods provide transcriptome-wide snapshots of RNA-protein interactions in live cells. Reverse transcriptases stopping at cross-linked nucleotides sign for RNA-protein binding sites. Reading through cross-linked positions results in false binding site assignments. In the 'monitored enhanced CLIP' (meCLIP) method, a barcoded biotiny-lated linker is ligated at the 5 end of cross-linked RNA fragments to purify RNA prior to the reverse transcription. cDNAs keeping the barcode sequence correspond to reverse transcription read-throughs. Read through occurs in unpredictable proportions, representing up to one fourth of total reads. Filtering out those reads strongly improves reliability and precision in protein binding site assignment

microRNA-seq of cartilage reveals an over-abundance of miR-140-3p which contains functional isomiRs

miR-140 is selectively expressed in cartilage. Deletion of the entire Mir140 locus in mice results in growth retardation and early-onset osteoarthritis-like pathology; however, the relative contribution of miR-140-5p or miR-140-3p to the phenotype remains to be determined. An unbiased small RNA sequencing approach identified miR-140-3p as significantly more abundant (>10-fold) than miR-140-5p in human cartilage. Analysis of these data identified multiple miR-140-3p isomiRs differing from the miRBase annotation at both the 5' and 3' end, with >99% having one of two seed sequences (5' bases 2-8). Canonical (miR-140-3p.2) and shifted (miR-140-3p.1) seed isomiRs were overexpressed in chondrocytes and transcriptomics performed to identify targets. miR-140-3p.1 and miR-140-3p.2 significantly down-regulated 694 and 238 genes, respectively, of which only 162 genes were commonly down-regulated. IsomiR targets were validated using 3'UTR luciferase assays. miR-140-3p.1 targets were enriched within up-regulated genes in rib chondrocytes of Mir140- null mice and within down-regulated genes during human chondrogenesis. Finally, through imputing the expression of miR-140 from the expression of the host gene WWP2 in 124 previously published data sets, an inverse correlation with miR-140-3p.1 predicted targets was identified. Together these data suggest the novel seed containing isomiR miR-140- 3p.1 is more functional than original consensus miR-140-3p seed containing isomiR

KARR-seq reveals cellular higher-order RNA structures and RNA–RNA interactions

RNA fate and function are affected by their structures and interactomes. However, how RNA and RNA-binding proteins (RBPs) assemble into higher-order structures and how RNA molecules may interact with each other to facilitate functions remain largely unknown. Here we present KARR-seq, which uses N3-kethoxal labeling and multifunctional chemical crosslinkers to covalently trap and determine RNA–RNA interactions and higher-order RNA structures inside cells, independent of local protein binding to RNA. KARR-seq depicts higher-order RNA structure and detects widespread intermolecular RNA–RNA interactions with high sensitivity and accuracy. Using KARR-seq, we show that translation represses mRNA compaction under native and stress conditions. We determined the higher-order RNA structures of respiratory syncytial virus (RSV) and vesicular stomatitis virus (VSV) and identified RNA–RNA interactions between the viruses and the host RNAs that potentially regulate viral replication

RNA analysis of nasopharyngeal swab

The nasopharyngeal swab is a very heterogeneous easily available sample which is used to diagnose infectious diseases of the upper respiratory tract. Recently, the swab is increasingly used in biomedical research. The nasopharynx is the place of contact between the external and internal surrounding of an individual and the first immune response to the intrusion of pathogens. Mucosal damage initiates inflammatory and regenerative processes. The nasopharyngeal mucosa is permanently inhabited by a large group of microorganisms which influence the process of the disease. Therefore, the nasopharyngeal swab is a very rich source of host cells and its microbiome. The introduction of the method of massive parallel sequencing, has developed and automated methods for DNA and RNA isolation. It also led to a significant reduction in the cost of their analysis and provides an information about the host genome, the presence of microorganisms and the current level of expression of host and pathogen genes as well. Thanks to the introduction of the single cell sequencing method, it is possible to monitor the interactions of individual cell types under physiological conditions and during the immune response. The aim of this work is to provide an overview of the biological function of the nasopharynx, its cellular...Nosohltanový stěr je velmi heterogenní snadno dostupný biologický materiál, který se využívá především k diagnostice infekčních onemocnění horních cest dýchacích. V poslední době je však čím dál více využíván i v biomedicínském výzkumu. Nosohltan je místem styku zevního a vnitřního prostředí jedince, je místem první imunitní odpovědi při vniknutí cizorodých látek či patogenů do dýchacích cest. Poškození sliznice spouští zánětlivé, reparační a regenerační procesy, kterých se účastní celá řada buněk imunitního systému. Sliznice nosohltanu jsou trvale osídleny rozsáhlou skupinou mikroorganismů, které mají vliv na propuknutí a průběh onemocnění. Nosohltanový stěr je tak velmi bohatým zdrojem širokého spektra buněk hostitele a jeho mikrobiomu. Zavedením metody masivního paralelního sekvenování došlo k rozvoji a automatizaci metod izolace DNA a RNA. Dále vedla k výraznému snížení nákladů na jejich analýzu a poskytuje řadu informací o genomu hostitele, zastoupení mikroorganismů, přítomnosti patogenů a také o aktuální výši exprese genů hostitele i patogenu. Díky zavedení metody single cell sekvenování je možné sledovat interakci jednotlivých buněčných typů za fyziologického stavu i během imunitní odpovědi. Cílem práce je poskytnout přehled o biologické funkci nosohltanu, jeho buněčném složení a metod RNA...Department of Genetics and MicrobiologyKatedra genetiky a mikrobiologieFaculty of SciencePřírodovědecká fakult

Trans-cellular control of synapse properties by a cell type-specific splicing regulator

The recognition of synaptic partners and specification of synaptic properties are fundamental for the function of neuronal circuits. ‘Terminal selector’ transcription factors coordinate the expression of terminal gene batteries that specify cell type-specific properties. Moreover, pan-neuronal alternative splicing regulators have been implicated in directing neuronal differentiation. However, the cellular logic of how splicing regulators instruct specific synaptic properties remains poorly understood. Here, we combine genome-wide mapping of mRNA targets and cell type-specific loss-of-function studies to uncover the contribution of the nuclear RNA binding protein SLM2 to hippocampal synapse specification. Focusing on hippocampal pyramidal cells and SST-positive GABAergic interneurons, we find that SLM2 preferentially binds and regulates alternative splicing of transcripts encoding synaptic proteins, thereby generating cell type-specific isoforms. In the absence of SLM2, cell type-specification, differentiation, and viability are unaltered and neuronal populations exhibit normal intrinsic properties. By contrast, cell type-specific loss of SLM2 results in highly selective, non-cell autonomous synaptic phenotypes, altered synaptic transmission, and associated defects in a hippocampus-dependent memory task. Thus, alternative splicing provides a critical layer of gene regulation that instructs specification of neuronal connectivity in a trans-synaptic manner

An mRNA processing pathway suppresses metastasis by governing translational control from the nucleus

Cancer cells often co-opt post-transcriptional regulatory mechanisms to achieve pathologic expression of gene networks that drive metastasis. Translational control is a major regulatory hub in oncogenesis; however, its effects on cancer progression remain poorly understood. Here, to address this, we used ribosome profiling to compare genome-wide translation efficiencies of poorly and highly metastatic breast cancer cells and patient-derived xenografts. We developed dedicated regression-based methods to analyse ribosome profiling and alternative polyadenylation data, and identified heterogeneous nuclear ribonucleoprotein C (HNRNPC) as a translational controller of a specific mRNA regulon. We found that HNRNPC is downregulated in highly metastatic cells, which causes HNRNPC-bound mRNAs to undergo 3′ untranslated region lengthening and, subsequently, translational repression. We showed that modulating HNRNPC expression impacts the metastatic capacity of breast cancer cells in xenograft mouse models. In addition, the reduced expression of HNRNPC and its regulon is associated with the worse prognosis in breast cancer patient cohorts

A Stress-Induced TRNA Depletion Response Mediates Codon-Based Translational Repression and Growth Suppression

Eukaryotic transfer RNAs (tRNAs) can become fragmented upon various cellular stresses, generating tRNA-derived RNA fragments (tRFs). Though this process has been observed for numerous cellular stresses and in many species ranging from plant cells to yeast and human cells, it is still poorly characterized and understood. Such tRNA fragmentation has previously been thought to affect a small fraction of the tRNA pool and was thus presumed to not affect the role of tRNAs in translation. We report that in human cells, oxidative stress can rapidly generate tRFs derived from tyrosyl tRNAGUA—resulting in a significant depletion of the precursor tRNA molecule and mature tRNA while also leading to elevated levels of the tRF. Proteomic and ribosomal profiling of tyrosyl tRNAGUA-depleted cells revealed impaired expression of proteins enriched in its cognate tyrosine codons, comprising growth and metabolic genes. Consistent with these affected pathways, depletion of tyrosyl tRNAGUA or its downstream targets, EPCAM, SCD, or USP3, repressed growth—revealing a tRNA-dependent growth suppressive pathway for oxidative stress response. A synthetic mimetic of the tRF induced upon oxidative stress was used to identify interactions with RNA binding proteins through mass spectrometry. High-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) of hnRNPA1 and SSB confirmed the mass spectrometry results and identified endogenous reciprocal interactions between the protein and tRF. Binding of this tRF to hnRNPA1 inhibits destabilization of endogenous targets of this RNA binding protein, leading to increased mRNA expression of DNA damage response and cell cycle regulatory genes. Thus, tRNA fragmentation can both deplete a precursor tRNA molecule with codon-dependent regulatory consequences and also generate small-RNAs that can interact with and regulate RNA binding proteins