Ribosome Footprint Profiling of Translation throughout the Genome

Toxic effects and transcriptome analysis of the early life stages of Larimichthys crocea exposed to the bloom-forming dinoflagellate Alexandrium tamarense

This study investigated the effects of the bloom-forming dinoflagellate Alexandrium tamarense and its potentially associated paralytic shellfish toxins on the early life stages of Larimichthys crocea (large yellow croaker) by integrating physiological effects with transcriptomic analysis to explore the molecular mechanisms underlying these harmful impacts. The results showed that 48-h acute exposure to A. tamarense culture and cell-free filtrate significantly reduced the heart rate in embryos and increased mortality rates in both embryos and larvae. Transcriptome sequencing of the filtrate-exposed group identified 130 differentially expressed genes in the embryo group and 884 in the juvenile group. Further analysis revealed that algal exposure triggered the activation of innate immunity in embryos, as evidenced by the significant upregulation of immune-related cytokines such as CCL20, IL11, and ILRA10. These genes were enriched in the cytokine-cytokine receptor interaction pathway and may induce immune responses through their respective downstream pathways. Additionally, the downregulation of the RNA polymerase and ribosome pathways suggests that protein synthesis was affected during the embryo stress response induced by A. tamarense. In juveniles, genes related to cardiac function, particularly those associated with myocardial contraction and calcium ion regulation, were downregulated after exposure to algal filtrate, further suggesting that A. tamarense, possibly through paralytic shellfish toxins, inhibits the heart function of L. crocea. The findings of this study elucidate the toxicological mechanisms of A. tamarense on the early life stages of L. crocea, providing scientific evidence for the impact of harmful algal blooms on marine life health and offering valuable insights for management strategies in aquaculture.

The m6A demethylase FTO promotes C/EBPβ-LIP translation to perform oncogenic functions in breast cancer cells

N6-methyladenosine (m6A) is a prevalent posttranscriptional mRNA modification involved in the regulation of transcript turnover, translation, and other aspects of RNA fate. The modification is mediated by multicomponent methyltransferase complexes (so-called writers) and is reversed through the action of the m6A-demethylases fat mass and obesity-associated (FTO) and alkB homolog 5 (ALKBH5) (so-called erasers). FTO promotes cell proliferation, colony formation and metastasis in models of triple-negative breast cancer (TNBC). However, little is known about genome-wide or specific downstream regulation by FTO. Here, we examined changes in the genome-wide transcriptome and translatome following FTO knockdown in TNBC cells. Unexpectedly, FTO knockdown had a limited effect on the translatome, while transcriptome analysis revealed that genes related to extracellular matrix (ECM) and epithelial-mesenchymal transition (EMT) are regulated through yet unidentified mechanisms. Differential translation of CEBPB mRNA into the C/EBPβ transcription factor isoform C/EBPβ-LIP is known to act in a pro-oncogenic manner in TNBC cells through regulation of EMT genes. Here we show that FTO is required for efficient C/EBPβ-LIP expression, suggesting that FTO has oncogenic functions through regulation of C/EBPβ-LIP.

Ribo-seq guided design of enhanced protein secretion in Komagataellaphaffii

The production of recombinant proteins requires the precise coordination of various biological processes, including protein synthesis, folding, trafficking, and secretion. The overproduction of a heterologous protein can impose various bottlenecks on these networks. Identifying and alleviating these bottlenecks can guide strain engineering efforts to enhance protein production. The methylotrophic yeast Komagataella phaffii is used for its high capacity to produce recombinant proteins. Here, we use ribosome profiling to identify bottlenecks in protein secretion during heterologous expression of human serum albumin (HSA). Validation of this analysis showed that the knockout of non-essential genes whose gene products target the ER, through co- and post-translational mechanisms, and have high ribosome utilization can increase production of a heterologous protein, HSA. A triple knockout in co-translationally translocated carbohydrate and acetate transporter Gal2p, cell wall maintenance protein Ydr134cp, and the post-translationally translocated cell wall protein Aoa65896.1 increased HSA production by 35 %. This data-driven strain engineering approach uses cell-level information to identify gene targets for phenotype improvement. This specific case identifies hits and creates strains with improved HSA production, with Ribo-seq and bioinformatic analysis to identify non-essential ER targeted proteins that are high ribosome utilizers.

Current Analytical Strategies for mRNA-Based Therapeutics

Recent advancements in mRNA technology, utilized in vaccines, immunotherapies, protein replacement therapies, and genome editing, have emerged as promising and increasingly viable treatments. The rapid, potent, and transient properties of mRNA-encoded proteins make them attractive tools for the effective treatment of a variety of conditions, ranging from infectious diseases to cancer and single-gene disorders. The capability for rapid and large-scale production of mRNA therapeutics fueled the global response to the COVID-19 pandemic. For effective clinical implementation, it is crucial to deeply characterize and control important mRNA attributes such as purity/integrity, identity, structural quality features, and functionality. This implies the use of powerful and advanced analytical techniques for quality control and characterization of mRNA. Improvements in analytical techniques such as electrophoresis, chromatography, mass spectrometry, sequencing, and functionality assessments have significantly enhanced the quality and detail of information available for product and process characterization, as well as for routine stability and release testing. Here, we review the latest advancements in analytical techniques for the characterization of mRNA-based therapeutics, typically employed by the biopharmaceutical industry for eventual market release.

Micropeptides derived from long non-coding RNAs: Computational analysis and functional roles in breast cancer and other diseases

Long non-coding RNAs (lncRNAs), once thought to be mere transcriptional noise, are now revealing a hidden code. Recent advancements like ribosome sequencing have unveiled that many lncRNAs harbor small open reading frames and can potentially encode functional micropeptides. Emerging research suggests these micropeptides, not the lncRNAs themselves, play crucial roles in regulating homeostasis, inflammation, metabolism, and especially in breast cancer progression. This review delves into the rapidly evolving computational tools used to predict and validate lncRNA-encoded micropeptides. We then explore the diverse functions and mechanisms of action of these micropeptides in breast cancer pathogenesis, with a focus on their roles in various species. Ultimately, this review aims to illuminate the functional landscape of lncRNA-encoded micropeptides and their potential as therapeutic targets in cancer.

Genome-wide changes of protein translation levels for cell and organelle proliferation in a simple unicellular alga

Cell proliferation is a fundamental characteristic of organisms, driven by the holistic functions of multiple proteins encoded in the genome. However, the individual contributions of thousands of genes and the millions of protein molecules they express to cell proliferation are still not fully understood, even in simple eukaryotes. Here, we present a genome-wide translation map of cells during proliferation in the unicellular alga Cyanidioschyzon merolae, based on the sequencing of ribosome-protected messenger RNA fragments. Ribosome profiling has revealed both qualitative and quantitative changes in protein translation for each gene during cell division, driven by the large-scale reallocation of ribosomes. Comparisons of ribosome footprints from non-dividing and dividing cells allowed the identification of proteins involved in cell proliferation. Given that in vivo experiments on two selected candidate proteins identified a division-phase-specific mitochondrial nucleoid protein and a mitochondrial division protein, further analysis of the candidate proteins may offer key insights into the comprehensive mechanism that facilitate cell and organelle proliferation.

Evaluation of Eukaryotic mRNA Coding Potential

It is widely discussed that eukaryotic mRNAs can encode several functional polypeptides. Recent progress in NGS and proteomics techniques has resulted in a huge volume of information on potential alternative translation initiation sites and open reading frames (altORFs). However, these data are still incomprehensive, and the vast majority of eukaryotic mRNAs annotated in conventional databases (e.g., GenBank) contain a single ORF (CDS) encoding a protein larger than some arbitrary threshold (commonly 100 amino acid residues). Indeed, some gene functions may relate to the polypeptides encoded by unannotated altORFs, and insufficient information in nucleotide sequence databanks may limit the interpretation of genomics and transcriptomics data. However, despite the need for special experiments to predict altORFs accurately, there are some simple methods for their preliminary mapping.

Proteomics Can Rise to the Challenge of Pseudogenes' Coding Nature

Throughout the past decade, technological advances in genomics and transcriptomics have revealed pervasive translation throughout mammalian genomes. These putative proteins are usually excluded from proteomics analyses, as they are absent from common protein repositories. A sizable portion of these noncanonical proteins is translated from pseudogenes. Pseudogenes are commonly termed defective copies of coding genes unable to produce proteins. Here, we suggest that proteomics can help in their annotation. First, we define important terms and review specific examples underlining the caveats in pseudogene annotation and their coding potential. Then, we will discuss the challenges inherent to pseudogenes that have thus far rendered complex their confidence in omics data. Finally, we identify recent developments in experimental procedures, instrumentation, and computational methods in proteomics that put the field in a unique position to solve the pseudogene annotation conundrum.

Selenocysteine tRNA methylation promotes oxidative stress resistance in melanoma metastasis

Selenocysteine-containing proteins play a central role in redox homeostasis. Their translation is a highly regulated process and is dependent on two tRNASec isodecoders differing by a single 2'-O-ribose methylation called Um34. Here we characterized FTSJ1 as the Um34 methyltransferase and show that its activity is required for efficient selenocysteine insertion at the UGA stop codon during translation. Specifically, loss of Um34 leads to ribosomal stalling and decreased UGA recoding. FTSJ1-deficient cells are more sensitive to oxidative stress and show decreased metastatic colonization in xenograft models of melanoma metastasis. We found that FTSJ1 mediates efficient translation of selenoproteins essential for the cellular antioxidant response. Our findings uncover a role for tRNASec Um34 modification in oxidative stress resistance and highlight FTSJ1 as a potential therapeutic target specific for metastatic disease.

The early transcriptional and post-transcriptional responses to fluconazole in sensitive and resistant Candida albicans

Candida albicans is a leading cause of fungal infections in immunocompromised patients. Management of candidemia relies on a few antifungal agents, with fluconazole being first line therapy. The emergence of fluconazole-resistant strains highlights the pressing need to improve our molecular understanding of the drug response mechanisms. By sequencing the 5'P mRNA degradation intermediates, we establish that co-translational mRNA decay occurs in C. albicans and characterize how in vivo 5´-3´ exonuclease degradation trails the last translating ribosome. Thus, the study of the 5' Phosphorylated mRNA degradome (5PSeq) offers a simple and affordable way to measure ribosome dynamics and identify codon specific ribosome stalls in response to drugs and amino acid deprivation. Building upon this, we combine RNA-Seq and 5PSeq to study the early response of sensitive and resistant C. albicans isolates to fluconazole. Our results highlight that transcriptional responses, rather than changes in ribosome dynamics, are the main driver of Candida resistance to fluconazole.

Re-appraising the evidence for the source, regulation and function of p53-family isoforms

The p53 family of proteins evolved from a common ancestor into three separate genes encoding proteins that act as transcription factors with distinct cellular roles. Isoforms of each member that lack specific regions or domains are suggested to result from alternative transcription start sites, alternative splicing or alternative translation initiation, and have the potential to exponentially increase the functional repertoire of each gene. However, evidence supporting the presence of individual protein variants at functional levels is often limited and is inferred by mRNA detection using highly sensitive amplification techniques. We provide a critical appraisal of the current evidence for the origins, expression, functions and regulation of p53-family isoforms. We conclude that despite the wealth of publications, several putative isoforms remain poorly established. Future research with improved technical approaches and the generation of isoform-specific protein detection reagents is required to establish the physiological relevance of p53-family isoforms in health and disease. In addition, our analyses suggest that p53-family variants evolved partly through convergent rather than divergent evolution from the ancestral gene.

A mild case of Cockayne syndrome with a novel start-loss variant of ERCC8

Cockayne syndrome (CS) is a progressive multisystem disorder characterized by growth failure, microcephaly, developmental delay, and photosensitivity. The characteristic symptoms appear during early childhood in most patients with CS. Herein, we report a mild case of CS with a novel start-loss variant in ERCC8 that did not show the characteristic symptoms of CS during early childhood and exhibited sudden growth failure after the age of 10 years.

Long non-coding RNA-encoded micropeptides: functions, mechanisms and implications

Long non-coding RNAs (lncRNAs) are typically described as RNA transcripts exceeding 200 nucleotides in length, which do not code for proteins. Recent advancements in technology, including ribosome RNA sequencing and ribosome nascent-chain complex sequencing, have demonstrated that many lncRNAs retain small open reading frames and can potentially encode micropeptides. Emerging studies have revealed that these micropeptides, rather than lncRNAs themselves, are responsible for vital functions, including but not limited to regulating homeostasis, managing inflammation and the immune system, moderating metabolism, and influencing tumor progression. In this review, we initially outline the rapidly advancing computational analytical methods and public tools to predict and validate the potential encoding of lncRNAs. We then focus on the diverse functions of micropeptides and their underlying mechanisms in the pathogenesis of disease. This review aims to elucidate the functions of lncRNA-encoded micropeptides and explore their potential applications as therapeutic targets in cancer.

Uncovering the small proteome of Methanosarcina mazei using Ribo-seq and peptidomics under different nitrogen conditions

The mesophilic methanogenic archaeal model organism Methanosarcina mazei strain Gö1 is crucial for climate and environmental research due to its ability to produce methane. Here, we establish a Ribo-seq protocol for M. mazei strain Gö1 under two growth conditions (nitrogen sufficiency and limitation). The translation of 93 previously annotated and 314 unannotated small ORFs, coding for proteins ≤ 70 amino acids, is predicted with high confidence based on Ribo-seq data. LC-MS analysis validates the translation for 62 annotated small ORFs and 26 unannotated small ORFs. Epitope tagging followed by immunoblotting analysis confirms the translation of 13 out of 16 selected unannotated small ORFs. A comprehensive differential transcription and translation analysis reveals that 29 of 314 unannotated small ORFs are differentially regulated in response to nitrogen availability at the transcriptional and 49 at the translational level. A high number of reported small RNAs are emerging as dual-function RNAs, including sRNA154, the central regulatory small RNA of nitrogen metabolism. Several unannotated small ORFs are conserved in Methanosarcina species and overproducing several (small ORF encoded) small proteins suggests key physiological functions. Overall, the comprehensive analysis opens an avenue to elucidate the function(s) of multitudinous small proteins and dual-function RNAs in M. mazei.

The eukaryotic translation initiation factor eIF4E regulates flowering and circadian rhythm in Arabidopsis

Translation initiation is a critical, rate-limiting step in protein synthesis. The eukaryotic translation initiation factor 4E (eIF4E) plays an essential role in this process. However, the mechanisms by which eIF4E-dependent translation initiation regulates plant growth and development remain not fully understood. In this study, we found that Arabidopsis eIF4E proteins are distributed in both the nucleus and cytoplasm, with only the cytoplasmic eIF4E being involved in the control of photoperiodic flowering. Genome-wide translation profiling using Ribo-tag sequencing reveals that eIF4E may regulate plant flowering by maintaining the homeostatic translation of components in the photoperiodic flowering pathway. eIF4E not only regulates the translation of flowering genes such as FLOWERING LOCUS T (FT) and FLOWERING LOCUS D (FLD) but also influences the translation of circadian genes like CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and PSEUDO-RESPONSE REGULATOR 9 (PRR9). Consistently, our results show that the eIF4E modulates the rhythmic oscillation of the circadian clock. Together, our study provides mechanistic insights into how the protein translation regulates multiple developmental processes in Arabidopsis, including the circadian clock and photoperiodic flowering.

Mutant NPM1 marginally impacts ribosome footprint in acute myeloid leukemia cells

Background

NPM1-mutated acute myeloid leukemia (AML) is the most frequent AML subtype. As wild-type NPM1 is known to orchestrate ribosome biogenesis, it has been hypothesized that altered translation may contribute to leukemogenesis and leukemia maintenance in NPM1-mutated AML. However, this hypothesis has never been investigated. We reasoned that if mutant NPM1 (NPM1c) directly impacts translation in leukemic cells, loss of NPM1c would result in acute changes in the ribosome footprint.

Methods

Here, we performed ribosome footprint profiling (Ribo-seq) and bulk messenger RNA (mRNA) sequencing in two NPM1-mutated cell lines engineered to express endogenous NPM1c fused to the FKBP (F36V) degron tag (degron cells).

Results and discussion

Incubation of degron cells with the small compound dTAG-13 enables highly specific degradation of NPM1c within 4 hours. As expected, RNA-sequencing data showed early loss of homeobox gene expression following NPM1c degradation, confirming the reliability of our model. In contrast, Ribo-seq data showed negligible changes in the ribosome footprint in both cell lines, implying that the presence of NPM1c does not influence ribosome abundance and positioning on mRNA. While it is predictable that NPM1c exerts its leukemogenic activity at multiple levels, ribosome footprint does not seem influenced by the presence of mutant NPM1.

Genome-wide impact of codon usage bias on translation optimization in Drosophila melanogaster

Accuracy and efficiency are fundamental to mRNA translation. Codon usage bias is widespread across species. Despite the long-standing association between optimized codon usage and improved translation, our understanding of its evolutionary basis and functional effects remains limited. Drosophila is widely used to study codon usage bias, but genome-scale experimental data are scarce. Using high-resolution mass spectrometry data from Drosophila melanogaster, we show that optimal codons have lower translation errors than nonoptimal codons after accounting for these biases. Genomic-scale analysis of ribosome profiling data shows that optimal codons are translated more rapidly than nonoptimal codons. Although we find no long-term selection favoring synonymous mutations in D. melanogaster after diverging from D. simulans, we identify signatures of positive selection driving codon optimization in the D. melanogaster population. These findings expand our understanding of the functional consequences of codon optimization and serve as a foundation for future investigations.

Microscale marvels: unveiling the macroscopic significance of micropeptides in human health

Non-coding RNA encodes micropeptides from small open reading frames located within the RNA. Interestingly, these micropeptides are involved in a variety of functions within the body. They are emerging as the resolving piece of the puzzle for complex biomolecular signaling pathways within the body. Recent studies highlight the pivotal role of small peptides in regulating important biological processes like DNA repair, gene expression, muscle regeneration, immune responses, etc. On the contrary, altered expression of micropeptides also plays a pivotal role in the progression of various diseases like cardiovascular diseases, neurological disorders and several types of cancer, including colorectal cancer, hepatocellular cancer, lung cancer, etc. This review delves into the dual impact of micropeptides on health and pathology, exploring their pivotal role in preserving normal physiological homeostasis and probing their involvement in the triggering and progression of diseases.

Calorie restriction and rapamycin distinctly restore non-canonical ORF translation in the muscles of aging mice

Loss of protein homeostasis is one of the hallmarks of aging. As such, interventions that restore proteostasis should slow down the aging process and improve healthspan. Two of the most broadly used anti-aging interventions that are effective in organisms from yeast to mammals are calorie restriction (CR) and rapamycin (RM) treatment. To identify the regulatory mechanisms by which these interventions improve the protein homeostasis, we carried out ribosome footprinting in the muscle of mice aged under standard conditions, or under long-term treatment with CR or RM. We found that the treatments distinctly impact the non-canonical translation, RM primarily remodeling the translation of upstream open reading frames (uORFs), while CR restores stop codon readthrough and the translation of downstream ORFs. Proteomics analysis revealed the expression of numerous non-canonical ORFs at the protein level. The corresponding peptides may provide entry points for therapies aiming to maintain muscle function and extend health span.

Optimization of ribosome profiling in plants including structural analysis of rRNA fragments

BACKGROUND

Ribosome profiling (or Ribo-seq) is a technique that provides genome-wide information on the translational landscape (translatome). Across different plant studies, variable methodological setups have been described which raises questions about the general comparability of data that were generated from diverging methodologies. Furthermore, a common problem when performing Ribo-seq are abundant rRNA fragments that are wastefully incorporated into the libraries and dramatically reduce sequencing depth. To remove these rRNA contaminants, it is common to perform preliminary trials to identify these fragments because they are thought to vary depending on nuclease treatment, tissue source, and plant species.

RESULTS

Here, we compile valuable insights gathered over years of generating Ribo-seq datasets from different species and experimental setups. We highlight which technical steps are important for maintaining cross experiment comparability and describe a highly efficient approach for rRNA removal. Furthermore, we provide evidence that many rRNA fragments are structurally preserved over diverse nuclease regimes, as well as across plant species. Using a recently published cryo-electron microscopy (cryo-EM) structure of the tobacco 80S ribosome, we show that the most abundant rRNA fragments are spatially derived from the solvent-exposed surface of the ribosome.

CONCLUSION

The guidelines presented here shall aid newcomers in establishing ribosome profiling in new plant species and provide insights that will help in customizing the methodology for individual research goals.

Experimental approaches to studying translation in plant semi-autonomous organelles

Plant mitochondria and chloroplasts are semi-autonomous organelles originated from free-living bacteria that have retained reduced genomes during evolution. As a consequence, relatively few of the mitochondrial and chloroplast proteins are encoded in the organellar genomes and synthesized by the organellar ribosomes. Since both organellar genomes encode mainly components of the energy transduction systems, oxidative phosphorylation in mitochondria and photosynthetic apparatus in chloroplasts, understanding organellar translation is critical for a thorough comprehension of key aspects of mitochondrial and chloroplast activity affecting plant growth and development. Recent studies have clearly shown that translation is a key regulatory node in the expression of plant organellar genes, underscoring the need for an adequate methodology to study this unique stage of gene expression. The organellar translatome can be analysed by studying newly synthesized proteins or the mRNA pool recruited to the organellar ribosomes. In this review, we present experimental approaches used for studying translation in plant bioenergetic organelles. Their benefits and limitations, as well as the critical steps, are discussed. Additionally, we briefly mention several recently developed strategies to study organellar translation that have not yet been applied to plants.

Translational Regulation of Duplicated Gene Expression Evolution in Allopolyploid Cotton

Polyploidy, a prevalent event in plant evolution, drives phenotypic diversification and speciation. While transcriptional changes and regulation in polyploids have been extensively studied, the translational level impact remains largely unexplored. To address this gap, we conducted a comparative transcriptomic and translatomic analysis of cotton leaves from allopolyploid species G. hirsutum (AD1) and G. barbadense (AD2) relative to their model A-genome and D-genome diploid progenitors. Our data revealed that while allopolyploidization significantly affects the transcriptional landscape, its impact on translation was relatively modest, evidenced by a narrower expression range and fewer expression changes in ribosome-protected fragments than in mRNA levels. Allopolyploid-specific changes commonly identified in both AD1 and AD2 were observed in 7393 genes at either transcriptional or translational levels. Interestingly, the majority of translational changes exhibited concordant down-regulation in both ribosome-protected fragments and mRNA, particularly associated with terpenoid synthesis and metabolism (352 genes). Regarding translational efficiency (TE), at least one-fifth of cotton genes exhibit translational level regulation, with a general trend of more down-regulation (13.9-15.1%) than up-regulation (7.3-11.2%) of TE. The magnitude of translational regulation was slightly reduced in allopolyploids compared with diploids, and allopolyploidy tends to have a more profound impact on genes and functional associations with ultra-low TE. Moreover, we demonstrated a reduced extent of homeolog expression biases during translation compared with transcription. Our study provides insights into the regulatory consequences of allopolyploidy post-transcription, contributing to a comprehensive understanding of regulatory mechanisms of duplicated gene expression evolution.

Legume-rhizobia symbiosis: Translatome analysis

Leguminous plants can establish endosymbiotic relationships with nitrogen-fixing soil rhizobacteria. Bacterial infection and nodule organogenesis are two independent but highly coordinated genetic programs that are active during this interaction. These genetic programs can be regulated along all the stages of gene expression. Most of the studies, for both eukaryotes and prokaryotes, focused on the transcriptional regulation level determining the abundance of mRNAs. However, it has been demonstrated that mRNA levels only sometimes correlate with the abundance or activity of the coded proteins. For this reason, in the past two decades, interest in the role of translational control of gene expression has increased, since the subset of mRNA being actively translated outperforms the information gained only by the transcriptome. In the case of legume-rhizobia interactions, the study of the translatome still needs to be explored further. Therefore, this review aims to discuss the methodologies for analyzing polysome-associated mRNAs at the genome-scale and their contribution to studying translational control to understand the complexity of this symbiotic interaction. Moreover, the Dual RNA-seq approach is discussed for its relevance in the context of a symbiotic nodule, where intricate multi-species gene expression networks occur.

Beyond traditional translation: ncRNA derived peptides as modulators of tumor behaviors

Within the intricate tapestry of molecular research, noncoding RNAs (ncRNAs) were historically overshadowed by a pervasive presumption of their inability to encode proteins or peptides. However, groundbreaking revelations have challenged this notion, unveiling select ncRNAs that surprisingly encode peptides specifically those nearing a succinct 100 amino acids. At the forefront of this epiphany stand lncRNAs and circRNAs, distinctively characterized by their embedded small open reading frames (sORFs). Increasing evidence has revealed different functions and mechanisms of peptides/proteins encoded by ncRNAs in cancer, including promotion or inhibition of cancer cell proliferation, cellular metabolism (glucose metabolism and lipid metabolism), and promotion or concerted metastasis of cancer cells. The discoveries not only accentuate the depth of ncRNA functionality but also open novel avenues for oncological research and therapeutic innovations. The main difficulties in the study of these ncRNA-derived peptides hinge crucially on precise peptide detection and sORFs identification. Here, we illuminate cutting-edge methodologies, essential instrumentation, and dedicated databases tailored for unearthing sORFs and peptides. In addition, we also conclude the potential of clinical applications in cancer therapy.

Nuclear release of eIF1 globally increases stringency of start-codon selection to preserve mitotic arrest physiology

Regulated start-codon selection has the potential to reshape the proteome through the differential production of uORFs, canonical proteins, and alternative translational isoforms. However, conditions under which start-codon selection is altered remain poorly defined. Here, using transcriptome-wide translation initiation site profiling, we reveal a global increase in the stringency of start-codon selection during mammalian mitosis. Low-efficiency initiation sites are preferentially repressed in mitosis, resulting in pervasive changes in the translation of thousands of start sites and their corresponding protein products. This increased stringency of start-codon selection during mitosis results from increased interactions between the key regulator of start-codon selection, eIF1, and the 40S ribosome. We find that increased eIF1-40S ribosome interactions during mitosis are mediated by the release of a nuclear pool of eIF1 upon nuclear envelope breakdown. Selectively depleting the nuclear pool of eIF1 eliminates the changes to translational stringency during mitosis, resulting in altered mitotic proteome composition. In addition, preventing mitotic translational rewiring results in substantially increased cell death and decreased mitotic slippage following treatment with anti-mitotic chemotherapeutics. Thus, cells globally control translation initiation stringency with critical roles during the mammalian cell cycle to preserve mitotic cell physiology.

Rules and impacts of nonsense-mediated mRNA decay in the degradation of long noncoding RNAs

Nonsense-mediated mRNA decay (NMD) is a quality-control process that selectively degrades mRNAs having premature termination codon, upstream open reading frame, or unusually long 3'UTR. NMD detects such mRNAs and rapidly degrades them during initial rounds of translation in the eukaryotic cells. Since NMD is a translation-dependent cytoplasmic mRNA surveillance process, the noncoding RNAs were initially believed to be NMD-resistant. The sequence feature-based analysis has revealed that many putative long noncoding RNAs (lncRNAs) have short open reading frames, most of which have translation potential. Subsequent transcriptome-based molecular studies showed an association of a large set of such putative lncRNAs with translating ribosomes, and some of them produce stable and functionally active micropeptides. The translationally active lncRNAs typically have relatively longer and unprotected 3'UTR, which can induce their NMD-dependent degradation. This review defines the mechanism and regulation of NMD-dependent degradation of lncRNAs and its impact on biological processes related to the functions of lncRNAs or their encoded micropeptides. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Turnover and Surveillance > Regulation of RNA Stability RNA in Disease and Development > RNA in Disease.

Micropeptides: potential treatment strategies for cancer

Some noncoding RNAs (ncRNAs) carry open reading frames (ORFs) that can be translated into micropeptides, although noncoding RNAs (ncRNAs) have been previously assumed to constitute a class of RNA transcripts without coding capacity. Furthermore, recent studies have revealed that ncRNA-derived micropeptides exhibit regulatory functions in the development of many tumours. Although some of these micropeptides inhibit tumour growth, others promote it. Understanding the role of ncRNA-encoded micropeptides in cancer poses new challenges for cancer research, but also offers promising prospects for cancer therapy. In this review, we summarize the types of ncRNAs that can encode micropeptides, highlighting recent technical developments that have made it easier to research micropeptides, such as ribosome analysis, mass spectrometry, bioinformatics methods, and CRISPR/Cas9. Furthermore, based on the distribution of micropeptides in different subcellular locations, we explain the biological functions of micropeptides in different human cancers and discuss their underestimated potential as diagnostic biomarkers and anticancer therapeutic targets in clinical applications, information that may contribute to the discovery and development of new micropeptide-based tools for early diagnosis and anticancer drug development.

The role of molecular chaperone CCT/TRiC in translation elongation: A literature review

Protein synthesis from mRNA is an energy-intensive and strictly controlled biological process. Translation elongation is a well-coordinated and multifactorial step in translation that ensures the accurate and efficient addition of amino acids to a growing nascent-peptide chain encoded in the sequence of messenger RNA (mRNA). Which undergoes dynamic regulation due to cellular state and environmental determinants. An expanding body of research points to translational elongation as a crucial process that controls the translation of an mRNA through multiple feedback mechanisms. Molecular chaperones are key players in protein homeostasis to keep the balance between protein synthesis, folding, assembly, and degradation. Chaperonin-containing tailless complex polypeptide 1 (CCT) or tailless complex polypeptide 1 ring complex (TRiC) is an essential eukaryotic molecular chaperone that plays an essential role in assisting cellular protein folding and suppressing protein aggregation. In this review, we give an overview of the factors that influence translation elongation, focusing on different functions of molecular chaperones in translation elongation, including how they affect translation rates and post-translational modifications. We also provide an understanding of the mechanisms by which the molecular chaperone CCT plays multiple roles in the elongation phase of eukaryotic protein synthesis.

Translation velocity determines the efficacy of engineered suppressor tRNAs on pathogenic nonsense mutations

Nonsense mutations - the underlying cause of approximately 11% of all genetic diseases - prematurely terminate protein synthesis by mutating a sense codon to a premature stop or termination codon (PTC). An emerging therapeutic strategy to suppress nonsense defects is to engineer sense-codon decoding tRNAs to readthrough and restore translation at PTCs. However, the readthrough efficiency of the engineered suppressor tRNAs (sup-tRNAs) largely varies in a tissue- and sequence context-dependent manner and has not yet yielded optimal clinical efficacy for many nonsense mutations. Here, we systematically analyze the suppression efficacy at various pathogenic nonsense mutations. We discover that the translation velocity of the sequence upstream of PTCs modulates the sup-tRNA readthrough efficacy. The PTCs most refractory to suppression are embedded in a sequence context translated with an abrupt reversal of the translation speed leading to ribosomal collisions. Moreover, modeling translation velocity using Ribo-seq data can accurately predict the suppression efficacy at PTCs. These results reveal previously unknown molecular signatures contributing to genotype-phenotype relationships and treatment-response heterogeneity, and provide the framework for the development of personalized tRNA-based gene therapies.

N-Acetyltransferase 10 represses Uqcr11 and Uqcrb independently of ac4C modification to promote heart regeneration

Translational control is crucial for protein production in various biological contexts. Here, we use Ribo-seq and RNA-seq to show that genes related to oxidative phosphorylation are translationally downregulated during heart regeneration. We find that Nat10 regulates the expression of Uqcr11 and Uqcrb mRNAs in mouse and human cardiomyocytes. In mice, overexpression of Nat10 in cardiomyocytes promotes cardiac regeneration and improves cardiac function after injury. Conversely, treating neonatal mice with Remodelin-a Nat10 pharmacological inhibitor-or genetically removing Nat10 from their cardiomyocytes both inhibit heart regeneration. Mechanistically, Nat10 suppresses the expression of Uqcr11 and Uqcrb independently of its ac4C enzyme activity. This suppression weakens mitochondrial respiration and enhances the glycolytic capacity of the cardiomyocytes, leading to metabolic reprogramming. We also observe that the expression of Nat10 is downregulated in the cardiomyocytes of P7 male pig hearts compared to P1 controls. The levels of Nat10 are also lower in female human failing hearts than non-failing hearts. We further identify the specific binding regions of Nat10, and validate the pro-proliferative effects of Nat10 in cardiomyocytes derived from human embryonic stem cells. Our findings indicate that Nat10 is an epigenetic regulator during heart regeneration and could potentially become a clinical target.

Modeling neurodevelopmental disorder-associated human AGO1 mutations in Caenorhabditis elegans Argonaute alg-1

MicroRNAs (miRNA) associate with Argonaute (AGO) proteins and repress gene expression by base pairing to sequences in the 3' untranslated regions of target genes. De novo coding variants in the human AGO genes AGO1 and AGO2 cause neurodevelopmental disorders (NDD) with intellectual disability, referred to as Argonaute syndromes. Most of the altered amino acids are conserved between the miRNA-associated AGO in Homo sapiens and Caenorhabditis elegans, suggesting that the human mutations could disrupt conserved functions in miRNA biogenesis or activity. We genetically modeled four human AGO1 mutations in C. elegans by introducing identical mutations into the C. elegans AGO1 homologous gene, alg-1. These alg-1 NDD mutations cause phenotypes in C. elegans indicative of disrupted miRNA processing, miRISC (miRNA silencing complex) formation, and/or target repression. We show that the alg-1 NDD mutations are antimorphic, causing developmental and molecular phenotypes stronger than those of alg-1 null mutants, likely by sequestrating functional miRISC components into non-functional complexes. The alg-1 NDD mutations cause allele-specific disruptions in mature miRNA profiles, accompanied by perturbation of downstream gene expression, including altered translational efficiency and/or messenger RNA abundance. The perturbed genes include those with human orthologs whose dysfunction is associated with NDD. These cross-clade genetic studies illuminate fundamental AGO functions and provide insights into the conservation of miRNA-mediated post-transcriptional regulatory mechanisms.

Riboformer: a deep learning framework for predicting context-dependent translation dynamics

Translation elongation is essential for maintaining cellular proteostasis, and alterations in the translational landscape are associated with a range of diseases. Ribosome profiling allows detailed measurements of translation at the genome scale. However, it remains unclear how to disentangle biological variations from technical artifacts in these data and identify sequence determinants of translation dysregulation. Here we present Riboformer, a deep learning-based framework for modeling context-dependent changes in translation dynamics. Riboformer leverages the transformer architecture to accurately predict ribosome densities at codon resolution. When trained on an unbiased dataset, Riboformer corrects experimental artifacts in previously unseen datasets, which reveals subtle differences in synonymous codon translation and uncovers a bottleneck in translation elongation. Further, we show that Riboformer can be combined with in silico mutagenesis to identify sequence motifs that contribute to ribosome stalling across various biological contexts, including aging and viral infection. Our tool offers a context-aware and interpretable approach for standardizing ribosome profiling datasets and elucidating the regulatory basis of translation kinetics.

Utilizing high-resolution ribosome profiling for the global investigation of gene expression in Chlamydomonas

Ribosome profiling (Ribo-seq) is a powerful method for the deep analysis of translation mechanisms and regulatory circuits during gene expression. Extraction and sequencing of ribosome-protected fragments (RPFs) and parallel RNA-seq yields genome-wide insight into translational dynamics and post-transcriptional control of gene expression. Here, we provide details on the Ribo-seq method and the subsequent analysis with the unicellular model alga Chlamydomonas reinhardtii (Chlamydomonas) for generating high-resolution data covering more than 10 000 different transcripts. Detailed analysis of the ribosomal offsets on transcripts uncovers presumable transition states during translocation of elongating ribosomes within the 5' and 3' sections of transcripts and characteristics of eukaryotic translation termination, which are fundamentally distinct for chloroplast translation. In chloroplasts, a heterogeneous RPF size distribution along the coding sequence indicates specific regulatory phases during protein synthesis. For example, local accumulation of small RPFs correlates with local slowdown of psbA translation, possibly uncovering an uncharacterized regulatory step during PsbA/D1 synthesis. Further analyses of RPF distribution along specific cytosolic transcripts revealed characteristic patterns of translation elongation exemplified for the major light-harvesting complex proteins, LHCs. By providing high-quality datasets for all subcellular genomes and attaching our data to the Chlamydomonas reference genome, we aim to make ribosome profiles easily accessible for the broad research community. The data can be browsed without advanced bioinformatic background knowledge for translation output levels of specific genes and their splice variants and for monitoring genome annotation.

A ubiquitous GC content signature underlies multimodal mRNA regulation by DDX3X

The road from transcription to protein synthesis is paved with many obstacles, allowing for several modes of post-transcriptional regulation of gene expression. A fundamental player in mRNA biology is DDX3X, an RNA binding protein that canonically regulates mRNA translation. By monitoring dynamics of mRNA abundance and translation following DDX3X depletion, we observe stabilization of translationally suppressed mRNAs. We use interpretable statistical learning models to uncover GC content in the coding sequence as the major feature underlying RNA stabilization. This result corroborates GC content-related mRNA regulation detectable in other studies, including hundreds of ENCODE datasets and recent work focusing on mRNA dynamics in the cell cycle. We provide further evidence for mRNA stabilization by detailed analysis of RNA-seq profiles in hundreds of samples, including a Ddx3x conditional knockout mouse model exhibiting cell cycle and neurogenesis defects. Our study identifies a ubiquitous feature underlying mRNA regulation and highlights the importance of quantifying multiple steps of the gene expression cascade, where RNA abundance and protein production are often uncoupled.

Innovative computational tools provide new insights into the polyploid wheat genome

Bread wheat (Triticum aestivum) is an important crop and serves as a significant source of protein and calories for humans, worldwide. Nevertheless, its large and allopolyploid genome poses constraints on genetic improvement. The complex reticulate evolutionary history and the intricacy of genomic resources make the deciphering of the functional genome considerably more challenging. Recently, we have developed a comprehensive list of versatile computational tools with the integration of statistical models for dissecting the polyploid wheat genome. Here, we summarize the methodological innovations and applications of these tools and databases. A series of step-by-step examples illustrates how these tools can be utilized for dissecting wheat germplasm resources and unveiling functional genes associated with important agronomic traits. Furthermore, we outline future perspectives on new advanced tools and databases, taking into consideration the unique features of bread wheat, to accelerate genomic-assisted wheat breeding.

Translatome and Transcriptome Analyses Reveal the Mechanism that Underlies the Enhancement of Salt Stress by the Small Peptide Ospep5 in Plants

Salt stress significantly impedes plant growth and the crop yield. This study utilized de novo transcriptome assembly and ribosome profiling to explore mRNA translation's role in rice salt tolerance. We identified unrecognized translated open reading frames (ORFs), including 42 upstream transcripts and 86 unannotated transcripts. A noteworthy discovery was the role of a small ORF, Ospep5, in conferring salt tolerance. Overexpression of Ospep5 in plants increased salt tolerance, while its absence led to heightened sensitivity. This hypothesis was corroborated by the findings that exogenous application of the synthetic small peptide Ospep5 bolstered salt tolerance in both rice and Arabidopsis. We found that the mechanism underpinning the Ospep5-mediated salt tolerance involves the maintenance of intracellular Na+/K+ homeostasis, facilitated by upregulation of high-affinity potassium transporters (HKT) and Na+/H+ exchangers (SOS1). Furthermore, a comprehensive multiomics approach, particularly ribosome profiling, is instrumental in uncovering unannotated ORFs and elucidating their functions in plant stress responses.

No country for old methods: New tools for studying microproteins

Microproteins encoded by small open reading frames (sORFs) have emerged as a fascinating frontier in genomics. Traditionally overlooked due to their small size, recent technological advancements such as ribosome profiling, mass spectrometry-based strategies and advanced computational approaches have led to the annotation of more than 7000 sORFs in the human genome. Despite the vast progress, only a tiny portion of these microproteins have been characterized and an important challenge in the field lies in identifying functionally relevant microproteins and understanding their role in different cellular contexts. In this review, we explore the recent advancements in sORF research, focusing on the new methodologies and computational approaches that have facilitated their identification and functional characterization. Leveraging these new tools hold great promise for dissecting the diverse cellular roles of microproteins and will ultimately pave the way for understanding their role in the pathogenesis of diseases and identifying new therapeutic targets.

Deficiency of the ribosomal protein uS10 (RPS20) reorganizes human cells translatome according to the abundance, CDS length and GC content of mRNAs

Ribosomal protein uS10, a product of the RPS20 gene, is an essential constituent of the small (40S) subunit of the human ribosome. Disruptive mutations in its gene are associated with a predisposition to hereditary colorectal carcinoma. Here, using HEK293T cells, we show that a deficiency of this protein leads to a decrease in the level of ribosomes (ribosomal shortage). RNA sequencing of the total and polysome-associated mRNA samples reveals hundreds of genes differentially expressed in the transcriptome (t)DEGs and translatome (p)DEGs under conditions of uS10 deficiency. We demonstrate that the (t)DEG and (p)DEG sets partially overlap, determine genes with altered translational efficiency (TE) and identify cellular processes affected by uS10 deficiency-induced ribosomal shortage. We reveal that translated mRNAs of upregulated (p)DEGs and genes with altered TE in uS10-deficient cells are generally more abundant and that their GC contents are significantly lower than those of the respective downregulated sets. We also observed that upregulated (p)DEGs have longer coding sequences. Based on our findings, we propose a combinatorial model describing the process of reorganization of mRNA translation under conditions of ribosomal shortage. Our results reveal rules according to which ribosomal shortage reorganizes the transcriptome and translatome repertoires of actively proliferating cells.

Molecular bases for strong phenotypic effects of single synonymous codon substitutions in the E. coli ccdB toxin gene

BACKGROUND

Single synonymous codon mutations typically have only minor or no effects on gene function. Here, we estimate the effects on cell growth of ~ 200 single synonymous codon mutations in an operonic context by mutating almost all positions of ccdB, the 101-residue long cytotoxin of the ccdAB Toxin-Antitoxin (TA) operon to most degenerate codons. Phenotypes were assayed by transforming the mutant library into CcdB sensitive and resistant E. coli strains, isolating plasmid pools, and subjecting them to deep sequencing. Since autoregulation is a hallmark of TA operons, phenotypes obtained for ccdB synonymous mutants after transformation in a RelE toxin reporter strain followed by deep sequencing provided information on the amount of CcdAB complex formed.

RESULTS

Synonymous mutations in the N-terminal region involved in translation initiation showed the strongest non-neutral phenotypic effects. We observe an interplay of numerous factors, namely, location of the codon, codon usage, t-RNA abundance, formation of anti-Shine Dalgarno sequences, predicted transcript secondary structure, and evolutionary conservation in determining phenotypic effects of ccdB synonymous mutations. Incorporation of an N-terminal, hyperactive synonymous mutation, in the background of the single synonymous codon mutant library sufficiently increased translation initiation, such that mutational effects on either folding or termination of translation became more apparent. Introduction of putative pause sites not only affects the translational rate, but might also alter the folding kinetics of the protein in vivo.

CONCLUSION

In summary, the study provides novel insights into diverse mechanisms by which synonymous mutations modulate gene function. This information is useful in optimizing heterologous gene expression in E. coli and understanding the molecular bases for alteration in gene expression that arise due to synonymous mutations.

SARS-CoV-2 infection engenders heterogeneous ribonucleoprotein interactions to impede translation elongation in the lungs

Translational regulation in tissue environments during in vivo viral pathogenesis has rarely been studied due to the lack of translatomes from virus-infected tissues, although a series of translatome studies using in vitro cultured cells with viral infection have been reported. In this study, we exploited tissue-optimized ribosome profiling (Ribo-seq) and severe-COVID-19 model mice to establish the first temporal translation profiles of virus and host genes in the lungs during SARS-CoV-2 pathogenesis. Our datasets revealed not only previously unknown targets of translation regulation in infected tissues but also hitherto unreported molecular signatures that contribute to tissue pathology after SARS-CoV-2 infection. Specifically, we observed gradual increases in pseudoribosomal ribonucleoprotein (RNP) interactions that partially overlapped the trails of ribosomes, being likely involved in impeding translation elongation. Contemporaneously developed ribosome heterogeneity with predominantly dysregulated 5 S rRNP association supported the malfunction of elongating ribosomes. Analyses of canonical Ribo-seq reads (ribosome footprints) highlighted two obstructive characteristics to host gene expression: ribosome stalling on codons within transmembrane domain-coding regions and compromised translation of immunity- and metabolism-related genes with upregulated transcription. Our findings collectively demonstrate that the abrogation of translation integrity may be one of the most critical factors contributing to pathogenesis after SARS-CoV-2 infection of tissues.

A ubiquitous GC content signature underlies multimodal mRNA regulation by DDX3X

The road from transcription to protein synthesis is paved with many obstacles, allowing for several modes of post-transcriptional regulation of gene expression. A fundamental player in mRNA biology is DDX3X, an RNA binding protein that canonically regulates mRNA translation. By monitoring dynamics of mRNA abundance and translation following DDX3X depletion, we observe stabilization of translationally suppressed mRNAs. We use interpretable statistical learning models to uncover GC content in the coding sequence as the major feature underlying RNA stabilization. This result corroborates GC content-related mRNA regulation detectable in other studies, including hundreds of ENCODE datasets and recent work focusing on mRNA dynamics in the cell cycle. We provide further evidence for mRNA stabilization by detailed analysis of RNA-seq profiles in hundreds of samples, including a Ddx3x conditional knockout mouse model exhibiting cell cycle and neurogenesis defects. Our study identifies a ubiquitous feature underlying mRNA regulation and highlights the importance of quantifying multiple steps of the gene expression cascade, where RNA abundance and protein production are often uncoupled.

Transcriptome-wide profiling of acute stress induced changes in ribosome occupancy level using external standards

Acute cellular stress is known to induce a global reduction in mRNA translation through suppression of cap dependent translation. Selective translation in response to acute stress has been shown to play important roles in regulating the stress response. However, accurately profiling translational changes transcriptome-wide in response to acute cellular stress has been challenging. Commonly used data normalization methods operate on the assumption that any systematic shifts are experimental artifacts. Consequently, if applied to profiling acute cellular stress-induced mRNA translation changes, these methods are expected to produce biased estimates. To address this issue, we designed, produced, and evaluated a panel of 16 oligomers to serve as external standards for ribosome profiling studies. Using Sodium Arsenite treatment-induced oxidative stress in lymphoblastoid cell lines as a model system, we applied spike-in oligomers as external standards. We found our spike-in oligomers to display a strong linear correlation between the observed and the expected quantification, with small ratio compression at the lower concentration range. Using the expected fold changes constructed from spike-in controls, we found in our dataset that TMM normalization, a popular global scaling normalization approach, produced 87.5% false positives at a significant cutoff that is expected to produce only 10% false positive discoveries. In addition, TMM normalization produced a systematic shift of fold change by 3.25 fold. These results highlight the consequences of applying global scaling approaches to conditions that clearly violate their key assumptions. In contrast, we found RUVg normalization using spike-in oligomers as control genes recapitulated the expected stress induced global reduction of translation and resulted in little, if any, systematic shifts in the expected fold change. Our results clearly demonstrated the utility of our spike-in oligomers, both for constructing expected results as controls and for data normalization.

Workability of mRNA Sequencing for Predicting Protein Abundance

Transcriptomics methods (RNA-Seq, PCR) today are more routine and reproducible than proteomics methods, i.e., both mass spectrometry and immunochemical analysis. For this reason, most scientific studies are limited to assessing the level of mRNA content. At the same time, protein content (and its post-translational status) largely determines the cell's state and behavior. Such a forced extrapolation of conclusions from the transcriptome to the proteome often seems unjustified. The ratios of "transcript-protein" pairs can vary by several orders of magnitude for different genes. As a rule, the correlation coefficient between transcriptome-proteome levels for different tissues does not exceed 0.3-0.5. Several characteristics determine the ratio between the content of mRNA and protein: among them, the rate of movement of the ribosome along the mRNA and the number of free ribosomes in the cell, the availability of tRNA, the secondary structure, and the localization of the transcript. The technical features of the experimental methods also significantly influence the levels of the transcript and protein of the corresponding gene on the outcome of the comparison. Given the above biological features and the performance of experimental and bioinformatic approaches, one may develop various models to predict proteomic profiles based on transcriptomic data. This review is devoted to the ability of RNA sequencing methods for protein abundance prediction.

VeloPro: A pipeline integrating Ribo-seq and AlphaFold deciphers association patterns between translation velocity and protein structure features

VeloPro integrates Ribo-seq data and AlphaFold2-predicted 3D protein structure information for characterization of the association patterns between translation velocity and many protein structure features in prokaryotic and eukaryotic organisms across different taxonomical clades such as bacteria, fungi, protozoa, nematode, plants, insect, and mammals. We illustrated that association patterns between translation velocity and protein structure features differ across organisms, partially reflecting their taxonomical relationship.

mRNA vaccine quality analysis using RNA sequencing

The success of mRNA vaccines has been realised, in part, by advances in manufacturing that enabled billions of doses to be produced at sufficient quality and safety. However, mRNA vaccines must be rigorously analysed to measure their integrity and detect contaminants that reduce their effectiveness and induce side-effects. Currently, mRNA vaccines and therapies are analysed using a range of time-consuming and costly methods. Here we describe a streamlined method to analyse mRNA vaccines and therapies using long-read nanopore sequencing. Compared to other industry-standard techniques, VAX-seq can comprehensively measure key mRNA vaccine quality attributes, including sequence, length, integrity, and purity. We also show how direct RNA sequencing can analyse mRNA chemistry, including the detection of nucleoside modifications. To support this approach, we provide supporting software to automatically report on mRNA and plasmid template quality and integrity. Given these advantages, we anticipate that RNA sequencing methods, such as VAX-seq, will become central to the development and manufacture of mRNA drugs.

Ribosome profiling in the Symbiodiniacean dinoflagellate Fugacium kawagutii shows coordinated protein synthesis of enzymes in different pathways at different times of day

Dinoflagellates respond to daily changes in light and dark by changes in cellular metabolism, yet the mechanisms used are still unclear. For example, Fugacium (previously Symbiodinium) kawagutii shows little difference in the transcriptome between day and night suggesting little transcriptional control over gene expression. Here, we have performed ribosome profiling at 2 h intervals over a daily light-dark cycle to assess the degree to which protein synthesis rates might change over the daily cycle. The number of F. kawagutii coding sequences with significant differences in the number of ribosome-protected fragments (RPF) over the 24-h cycle was 2923 using JTK_Cycle and 3655 using ECHO. The majority of the regulated transcripts showed peak translation at the onset of the dark period. The regulated sequences were assigned to different KEGG pathways and transcripts that were translated at roughly the same time were termed concurrently regulated. Both analyses revealed concurrent regulation of many transcripts whose gene products were involved in spliceosome or lysosome biogenesis with peak translation rates around the onset of the dark period, while others, involved in nitrate metabolism and ribosomal proteins, were preferentially translated around the onset of the day phase or the end of the night phase, respectively. In addition, some sequences involved in DNA synthesis were preferentially translated at the end of the day. We conclude that light-dark cycles seem able to synchronize translation of some transcripts encoding proteins involved in a range of different cellular processes, and propose that these changes may help the cells adapt and alter their metabolism as a function of the time of day.

Detection of Known and Novel Small Proteins in Pseudomonas stutzeri Using a Combination of Bottom-Up and Digest-Free Proteomics and Proteogenomics

Small proteins of around 50 aa in length have been largely overlooked in genetic and biochemical assays due to the inherent challenges with detecting and characterizing them. Recent discoveries of their critical roles in many biological processes have led to an increased recognition of the importance of small proteins for basic research and as potential new drug targets. One example is CcoM, a 36 aa subunit of the cbb3-type oxidase that plays an essential role in adaptation to oxygen-limited conditions in Pseudomonas stutzeri (P. stutzeri), a model for the clinically relevant, opportunistic pathogen Pseudomonas aeruginosa. However, as no comprehensive data were available in P. stutzeri, we devised an integrated, generic approach to study small proteins more systematically. Using the first complete genome as basis, we conducted bottom-up proteomics analyses and established a digest-free, direct-sequencing proteomics approach to study cells grown under aerobic and oxygen-limiting conditions. Finally, we also applied a proteogenomics pipeline to identify missed protein-coding genes. Overall, we identified 2921 known and 29 novel proteins, many of which were differentially regulated. Among 176 small proteins 16 were novel. Direct sequencing, featuring a specialized precursor acquisition scheme, exhibited advantages in the detection of small proteins with higher (up to 100%) sequence coverage and more spectral counts, including sequences with high proline content. Three novel small proteins, uniquely identified by direct sequencing and not conserved beyond P. stutzeri, were predicted to form an operon with a conserved protein and may represent de novo genes. These data demonstrate the power of this combined approach to study small proteins in P. stutzeri and show its potential for other prokaryotes.

Simultaneous measurement of nascent transcriptome and translatome using 4-thiouridine metabolic RNA labeling and translating ribosome affinity purification

Regulation of gene expression in response to various biological processes, including extracellular stimulation and environmental adaptation requires nascent RNA synthesis and translation. Analysis of the coordinated regulation of dynamic RNA synthesis and translation is required to determine functional protein production. However, reliable methods for the simultaneous measurement of nascent RNA synthesis and translation at the gene level are limited. Here, we developed a novel method for the simultaneous assessment of nascent RNA synthesis and translation by combining 4-thiouridine (4sU) metabolic RNA labeling and translating ribosome affinity purification (TRAP) using a monoclonal antibody against evolutionarily conserved ribosomal P-stalk proteins. The P-stalk-mediated TRAP (P-TRAP) technique recovered endogenous translating ribosomes, allowing easy translatome analysis of various eukaryotes. We validated this method in mammalian cells by demonstrating that acute unfolded protein response (UPR) in the endoplasmic reticulum (ER) induces dynamic reprogramming of nascent RNA synthesis and translation. Our nascent P-TRAP (nP-TRAP) method may serve as a simple and powerful tool for analyzing the coordinated regulation of transcription and translation of individual genes in various eukaryotes.

Unlocking the potential of non-coding RNAs in cancer research and therapy

Non-coding RNAs (ncRNAs) have emerged as key regulators of gene expression, with growing evidence implicating their involvement in cancer development and progression. The potential of ncRNAs as diagnostic and prognostic biomarkers for cancer is promising, with emphasis on their use in liquid biopsy and tissue-based diagnostics. In a nutshell, the review comprehensively summarizes the diverse classes of ncRNAs implicated in cancer, including microRNAs, long non-coding RNAs, and circular RNAs, and their functions and mechanisms of action. Furthermore, we describe the potential therapeutic applications of ncRNAs, including anti-miRNA oligonucleotides, siRNAs, and other RNA-based therapeutics in cancer treatment. However, significant challenges remain in developing effective ncRNA-based diagnostics and therapeutics, including the lack of specificity, limited understanding of mechanisms, and delivery challenges. This review also covers the current state-of-the-art non-coding RNA research technologies and bioinformatic analysis tools. Lastly, we outline future research directions in non-coding RNA research in cancer, including developing novel biomarkers, therapeutic targets, and modalities. In summary, this review provides a comprehensive understanding of non-coding RNAs in cancer and their potential clinical applications, highlighting both the opportunities and challenges in this rapidly evolving field.

Spatially resolved single-cell translatomics at molecular resolution

The precise control of messenger RNA (mRNA) translation is a crucial step in posttranscriptional gene regulation of cellular physiology. However, it remains a challenge to systematically study mRNA translation at the transcriptomic scale with spatial and single-cell resolution. Here, we report the development of ribosome-bound mRNA mapping (RIBOmap), a highly multiplexed three-dimensional in situ profiling method to detect cellular translatome. RIBOmap profiling of 981 genes in HeLa cells revealed cell cycle-dependent translational control and colocalized translation of functional gene modules. We mapped 5413 genes in mouse brain tissues, yielding spatially resolved single-cell translatomic profiles for 119,173 cells and revealing cell type-specific and brain region-specific translational regulation, including translation remodeling during oligodendrocyte maturation. Our method detected widespread patterns of localized translation in neuronal and glial cells in intact brain tissue networks.