RNA

The SARS-CoV-2 pandemic underscored the need for early, rapid, and widespread pathogen detection tests that are readily accessible. Many existing rapid isothermal detection methods employ the recombinase polymerase amplification (RPA), which exhibits PCR-like sensitivity, specificity, and even higher speed. However, coupling RPA to other enzymatic reactions has proven difficult. For the first time, we demonstrate that with tuning of buffer conditions and optimization of reagent concentrations, RPA can be cascaded into an in vitro transcription reaction, enabling detection using fluorescent aptamers in a one-pot reaction...

The sequence-specific RNA-binding protein Pumilio controls Drosophila development; however, the network of mRNAs that it regulates remains incompletely characterized. In this study, we utilize knockdown and knockout approaches coupled with RNA-Seq to measure the impact of Pumilio on the transcriptome of Drosophila cells in culture. We also use an improved RNA co-immunoprecipitation method to identify Pumilio-bound mRNAs in Drosophila embryos. Integration of these datasets with the locations of Pumilio binding motifs across the transcriptome reveal novel direct Pumilio target genes involved in neural, muscle, wing, and germ cell development, and cellular proliferation...

The Prp19 complex (Prp19C) also named NineTeen Complex (NTC) is conserved from yeast to human and functions in many different processes such as genome stability, splicing and transcription elongation. In the latter, Prp19C ensures TREX occupancy at transcribed genes. TREX in turn couples transcription to nuclear mRNA export by recruiting the mRNA exporter to transcribed genes and consequently to nascent mRNAs. Here, we assess the function of the nonessential Prp19C subunit Syf2 and the nonessential Prp19C-associated protein Cwc15 in the interaction of Prp19C and TREX with the transcription machinery, Prp19C and TREX occupancy as well as transcription elongation...

Several enzymes of intermediary metabolism have been identified to bind RNA in 2 cells, with potential consequences for the bound RNAs and/or the enzyme. In this 3 study, we investigate the RNA-binding activity of the mitochondrial enzyme malate 4 dehydrogenase 2 (MDH2), which functions in the tricarboxylic acid (TCA) cycle and 5 the malate-aspartate shuttle. We confirmed in cellulo RNA-binding of MDH2 using 6 orthogonal biochemical assays and performed enhanced crosslinking and 7 immunoprecipitation (eCLIP) to identify the cellular RNAs associated with endogenous 8 MDH2...

Ribosomes translate mRNA into proteins and are essential for every living organism. In eukaryotes both ribosomal subunits are rapidly assembled in a strict hierarchical order, starting in the nucleolus with transcription of a common precursor ribosomal RNA (pre-rRNA). This pre-rRNA encodes three of the four mature rRNAs which are formed by several, consecutive endonucleolytic and exonucleolytic processing steps. Historically, Northern Blots are used to analyze the variety of different pre-rRNA species, only allowing rough length estimations...

Forkhead box P3 (FOXP3) is the master fate-determining transcription factor in regulatory T (Treg) cells and is essential for their development, function and homeostasis. Mutations in FOXP3 cause immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome, and aberrant expression of FOXP3 has been implicated in other diseases such as multiple sclerosis and cancer. We previously demonstrated that pre-mRNA splicing of FOXP3 RNAs is highly sen-sitive to levels of DExD-box polypeptide 39B (DDX39B) and here we investigate the mechanism of this sensitivity...

Cancer cells can manipulate immune cells and escape from the immune system response. Quantifying the molecular changes that occur when an immune cell is touching a tumor cell can increase our understanding of the underlying mechanisms. Recently, it became possible to perform such measurements in situ, for example using expansion sequencing, which enabled in situ sequencing of genes with super-resolution. We systematically examined whether individual immune cells from specific cell types express genes differently when in physical proximity to individual tumor cells...

30S subunits become inactive upon exposure to low Mg2+ concentration, due to a reversible conformational change that entails nucleotides (nt) in the neck helix (h28) and 3' tail of 16S rRNA. This active-to-inactive transition involves partial unwinding of h28 and re-pairing of nt 921-923 with nt 1532-1534, which requires flipping of the 3' tail by ~180 degrees. Growing evidence suggests that immature 30S particles adopt the inactive conformation in the cell, and transition to the active state occurs at a late stage of maturation...

RNA thermometers are highly structured noncoding RNAs located in the 5' untranslated regions (UTR) of genes that regulate expression by undergoing conformational changes in response to temperature. The discovery of RNA thermometers through bioinformatics is difficult because there is little sequence conservation among their structural elements. Thus, the abundance of these thermo-sensitive regulatory structures remains unclear. Herein, to advance the discovery and validation of RNA thermometers, we developed Robo-Therm, a pipeline that combines an adaptive and user-friendly in silico motif search with a well-established reporter system...

The stem loop 2 motif (s2m) in SARS-CoV-2 (SCoV-2) is located in the 3'-UTR. Although s2m has been reported to display characteristics of a mobile genomic element that might lead to an evolutionary advantage, its function has remained unknown. The secondary structure of the original SCoV-2 RNA sequence (Wuhan-Hu-1) was determined by NMR in late 2020, delineating the base pairing pattern and revealing substantial differences in secondary structure compared to SARS-CoV-1 (SCoV-1). The existence of a single G29742-A29756 mismatch in the upper stem of s2m leads to its destabilization and impedes a complete NMR analysis...

3' end processing of most eukaryotic pre-mRNAs is a crucial co-transcriptional process that generally involves the cleavage and polyadenylation of the precursor transcripts. Within the human 3' end processing machinery, the 4-subunit mammalian polyadenylation specificity factor (mPSF) recognizes the polyadenylation signal (PAS) in the pre-mRNA and recruits the polyA polymerase α (PAPOA) to it. To shed light on the molecular mechanisms of PAPOA recruitment to mPSF, we used a combination of cryogenic-electron microscopy (cryo-EM) single-particle analysis, computational structure prediction and in vitro biochemistry to reveal an intricate interaction network...

In recent years, concerted efforts to map and understand epitranscriptomic modifications in mRNA have unveiled new complexities in the regulation of gene expression. These studies cumulatively point to diverse functions in mRNA metabolism, spanning pre-mRNA processing, mRNA degradation, and translation. However, this emerging landscape is not without its intricacies and sources of discrepancies. Disparities in detection methodologies, divergent interpretations of functional outcomes, and the complex nature of biological systems across different cell types pose significant challenges...

RNA 2'-O-methylation (Nm) is highly abundant in noncoding RNAs including ribosomal RNA (rRNA), transfer RNA (tRNA), and small nuclear RNA (snRNA), and occurs in the 5' cap of virtually all messenger RNAs (mRNAs) in higher eukaryotes. More recently, Nm has also been reported to occur at internal sites in mRNA. High-throughput methods have been developed for the transcriptome-wide detection of Nm. However, these methods have mostly been applied to abundant RNAs such as rRNA, and the validity of the internal mRNA Nm sites detected with these approaches remains controversial...

Inosine (I), resulting from the deamination of adenosine (A), is a prominent modification in the human transcriptome. The enzymes responsible for the conversion of adenosine to inosine in human mRNAs are the ADARs (adenosine deaminases acting on RNA). Inosine modification introduces a layer of complexity to mRNA processing and function, as it can impact various aspects of RNA biology, including mRNA stability, splicing, translation, and protein binding. The relevance of this process is emphasized in the growing number of human disorders associated with dysregulated A-to-I editing pathways...

In this article I recount my memories of key experiments that led to my entry into the RNA editing/modification field. I highlight initial observations made by the pioneers in the ADAR field, and how they fit into our current understanding of this family of enzymes. I discuss early mysteries that have now been solved, as well as those that still linger. Finally, I discuss important, outstanding questions and acknowledge my hope for the future of the RNA editing/modification field.

Pseudouridine is an abundant mRNA modification found in diverse organisms ranging from bacteria and viruses to multicellular plants and humans. New developments in pseudouridine profiling provide quantitative tools to map mRNA pseudouridylation sites. Sparse biochemical studies establish the potential for mRNA pseudouridylation to affect most stages of the mRNA life cycle from birth to death. This recent progress sets the stage for deeper investigations into the molecular and cellular functions of specific mRNA pseudouridines, including in disease...

No abstract text is available yet for this article.

Over the past decade, advancements in epitranscriptomics have significantly enhanced our understanding of mRNA metabolism and its role in human development and diseases. This period has witnessed breakthroughs in sequencing technologies, and the identification of key proteins involved in RNA modification processes. Besides the extensively studied m6A, Ψ and m1A modifications have risen as important epitranscriptomic marks. Alongside the well-studied m6A, Ψ and m1A have emerged as key epitranscriptomic markers...

N 1 -methyl adenosine (m1 A) is a wide-spread RNA modification present in tRNA, rRNA and mRNA. m1 A modification sites in tRNAs are evolutionary conserved and its formation on tRNA is catalyzed by methyltransferase TRMT61A and TRMT6 complex. m1 A promotes translation initiation and elongation. Due to its positive charge under physiological conditions, m1 A can notably modulate RNA structure. It also blocks Watson-Crick-Franklin base pairing and causes mutation and truncation during reverse transcription. Several misincorporation-based high throughput sequencing methods have been developed to sequence m1 A...

N6-methyladenosine (m6A) is the most prevalent modified nucleotide in mRNA and it has important functions in mRNA regulation. However, our understanding of the specific functions of m6A along with its cytosolic readers, the YTHDF proteins, has changed substantially in recent years. The original view was that different m6A sites within an mRNA could have different functions depending on which YTHDF paralog was bound to it, with bound YTHDF1 inducing translation while bound YTHDF2 inducing mRNA degradation. More recent data has called much of this into question, showing that all m6A sites bind all YTHDF proteins with equal ability, with a single primary function of all three YTHDF proteins to mediate mRNA degradation...