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Dense RNA motif modifications enable robust in vivo prime editing and enhance efficiencies of diverse editing systems.

Prime editing holds promise for therapeutic applications. However, viral delivery of the prime editor presents challenges for clinical translation due to concerns regarding long-term expression. Meanwhile, systemic delivery using non-viral vectors has been limited by low efficiency, the need for repeated injections and reliance on doses that exceed clinically translatable levels. Here we develop engineered prime editing guide RNAs (pegRNAs) with densely modified RNA motifs and demonstrate their application for efficient in vivo prime editing. By systemically delivering the prime editor in RNA format via a single injection of lipid nanoparticles, we achieved nearly 70% editing efficiency in the bulk mouse liver, indicating successful editing of the majority of hepatocytes. Notably, a single injection at a clinically translatable lipid nanoparticle dose was sufficient to suppress target protein expression in vivo, resulting in a near 80-fold increase in editing efficiency compared with conventional end-modified pegRNAs. Furthermore, incorporating densely modified RNA motifs, including the widely used MS2 motif, proved broadly applicable across various RNA sequences and split RNA-guided genome editing platforms, resulting in up to an 11-fold increase in base editing efficiency. These findings present a generalizable approach for enhancing the therapeutic potential of prime editing and expanding the utility of RNA-based therapeutics.

Journal Article

An expanded realm of anti-CRISPR-associated proteins and regulatory mechanisms.

Many bacteriophages encode anti-CRISPR (Acr) proteins that inhibit bacterial CRISPR-Cas immune systems. Rapid acr gene expression upon phage entry enables CRISPR-Cas neutralization but can impact phage fitness if unregulated. Therefore, Acr production is often controlled by distinct families of co-encoded anti-CRISPR-associated (Aca) proteins, which are usually helix-turn-helix (HTH) regulators that bind DNA within acr-aca operon promoters. Previously, we demonstrated that the Aca2 family additionally represses Acr production translationally by binding structured RNA motifs within the 5' untranslated region (UTR) of the acr-aca mRNA. Here, through systematic bioinformatic analyses, we provide evidence of structured RNA motifs in the 5' UTRs of operons encoding members of other Aca families and show that Aca1 also specifically binds its cognate RNA motif. Additionally, many Aca proteins are predicted to regulate not only their own but also adjacent operons with potential anti-defence genes. Indeed, we show that Aca14, newly identified in this study, represses two predicted anti-defence operons. Aca14 is a ribbon-helix-helix domain protein, revealing regulatory diversity beyond the canonical HTH Aca family members. Collectively, our findings expand our understanding of acr regulation in mobile genetic elements and reveal novel mechanisms by which phages fine-tune anti-defence gene expression.

5' Untranslated Regions

EWS-RNA Binding Protein 1: Structural Insights into Ewing Sarcoma by Conformational Dynamics Investigations.

BACKGROUND: Prior research has demonstrated that proteins play a significant role in the prognosis and treatments of various sarcomas, including Ewing sarcoma through the interplay of downstream signaling cascades. However, there is limited understanding about the strcucture conformation of EWSR1 and its structural implication in the prognosis of Ewsing Sarcoma by interaction with RNA molecules. AIMS: The primary goal of ongoing research is to determine how EWSR1 contributes to Ewing sarcoma. OBJECTIVE: The current study explores the complexity of EWSR1 structure and its conformational interactions with RNA in relation to Ewing sarcoma. METHODS: Here, we employed a comparative modeling approach to predict EWSR1 domains separately and assembled them into one structural unit using a DEMO server. Additionally, the RNA motifs interacting with EWSR1 were predicted, and the 3D model was built using RNAComposer. Protein-RNA docking and MD simulation studies were carried out to check the intermolecular interactions and stability behavior of docked EWSR1-RNA complexes. RESULTS: The overall results explore the structural insights into EWSR1 and their interactions with RNA, which may play a momentous role in co- and post-transcriptional regulation to control gene expression. CONCLUSION: Taken togather, our findings suggest that EWSR1 may be a useful therapeutic target for the diagnosis and management of Ewing sarcoma.

Sarcoma, Ewing

Ebola virus VP35 NNLNS motif modulates viral RNA synthesis and MIB2-mediated signaling.

Ebola virus (EBOV) is a nonsegmented, negative-sense virus (NNSV) with a single-stranded RNA genome. EBOV encodes for a limited number of proteins and thus depends on host factors to facilitate viral replication and pathogenesis. Of the virus-encoded proteins, multifunctional EBOV VP35 (eVP35) is necessary for host immune evasion and viral RNA synthesis. Previous proteomics studies identified an interaction between eVP35 and the host E3 ubiquitin ligase Mindbomb 2 (MIB2). Here, we show how an NNLNS (Asn-Asn-Leu-Asn-Ser) motif (residues 201 to 205) within eVP35 serves as a binding site for MIB2. This motif is critical for eVP35-dependent inhibition of MIB2-mediated interferon induction. It is also important for EBOV RNA synthesis as MIB2 binding to eVP35 inhibited EBOV minigenome activity. Altogether, these findings highlight the importance of the eVP35 protein and the role of host factors in EBOV infection.

Ebolavirus

TRIM63 Overexpression in FISH-Negative MiTF Family Altered Renal Cell Carcinoma (MiTF RCC).

TFE3 and TFEB break-apart fluorescent in situ hybridization (FISH) assays are the "gold standard" for diagnostic confirmation of microphthalmia-associated transcription factor (MiTF) family-altered renal cell carcinoma (MiTF RCC), which includes TFE3-rearranged RCC and TFEB-altered RCC. However, FISH assays, for multiple reasons, may lead to equivocal or false-negative results, especially in cryptic fusions resulting from intrachromosomal inversions involving 5' partner genes, such as non-POU domain-containing octamer-binding protein (NONO); GRIPI-associated protein 1 (GRIPAP1); RNA-binding motif protein, X chromosome (RBMX); and RNA-binding motif protein 10 (RBM10). When FISH results are negative in cases with strong morphological suspicion of the listed tumor entities, pathologists may recommend targeted RT-PCR or panel-based RNA fusion sequencing for diagnostic confirmation. Our recent RNA in situ hybridization (RNA ISH)-based study demonstrated RNA expression of the tripartite motif containing 63 (TRIM63) to be highly enriched in TFE3-rearranged RCC and TFEB-altered RCC, including 2 FISH false-negative RCC cases harboring RBM10::TFE3 fusion. Based on these observations, we hypothesized that TRIM63 positivity could aid in diagnosing cases that are negative by conventional FISH assay but remain morphologically suspicious, representing an unmet clinical need in this area. We collected 20 RCC cases with morphological suspicion (with equivocal/indeterminate immunohistochemistry panel) of MiTF RCC, which were TRIM63 positive, negative/equivocal for TFE3/TFEB gene rearrangement by FISH, and underwent next-generation sequencing (NGS). On NGS correlation, 14 of 20 (70%) FISH-negative TRIM63-positive tumors harbored an MiTF gene rearrangement. In the remaining 6 cases, we were unable to fully ascertain the MiTF rearrangement status due to the inherent limitation of the NGS panel utilized. The cases with MiTF gene rearrangement include TFE3 rearrangement in 60% (12/20) and TFEB low-level copy gains (with an additional missense mutation in 1 case) in 10% (2/20) of samples. RBM10:TFE3 fusion was seen in 67% (8/12) of TFE3-rearranged RCC in this cohort. TRIM63 RNA ISH assay could aid in identifying cases that harbor TFE3 or TFEB rearrangement associated with false-negative or equivocal TFE3/TFEB FISH results, especially those involving gene fusions with a paracentric Xp11 inversion. Overall, employment of TRIM63 RNA ISH coupled with TFE3/TFEB FISH assays and follow-up genomic interrogation enhanced diagnostic accuracy for patients with MiTF RCC.

Carcinoma, Renal Cell

The cellular protein TIAR mediates rapid initiation of West Nile virus genome RNA synthesis.

During the intracellular replication cycle of West Nile virus (WNV), genome RNA synthesis is initially inefficient but increases exponentially as viral replication complexes are sequestered in invaginations in the endoplasmic reticulum. In this study, we investigated the functional role of the cellular protein TIAR (T-cell intracellular antigen-related protein) in the transcription of WNV genome RNA. Close colocalization of cytoplasmic TIAR with viral double-stranded RNA was detected by a proximity ligation assay in WNV-infected cells. TIAR binds specifically to the WNV 3'(-) SL but not to the complementary WNV 5'(+) SL in in vitro RNA binding assays. Only the 3' end of the WNV minus-strand RNA was enriched by immunoprecipitation of infected cell lysates with anti-TIAR antibody. Stable overexpression of TIAR in clonal A549 cells increased the ratio of intracellular viral plus-strand to minus-strand RNA in a dose-dependent manner. TIAR contains three RNA recognition motifs (RRMs). Biophysical data indicated that only RRM2 directly contacts RNA and that up to three TIAR molecules can bind cooperatively to the WNV 3'(-) SL RNA. These data provide additional evidence that TIAR functions as a proviral host factor facilitating exponential amplification of WNV genome production in infected cells.IMPORTANCEWest Nile virus (WNV) is a mosquito-borne orthoflavivirus associated with increasing global human disease incidence. The molecular mechanisms underlying viral replication are not fully understood. In early stages of infection, viral genome transcription is inefficient; however, in late stages, viral genome transcription increases exponentially. T-cell intracellular antigen-related (TIAR) protein is a cellular protein that has been shown to interact with the 3' end of the WNV negative-sense antigenomic RNA. We obtained data showing colocalization of cellular TIAR with viral replication complexes in infected cells and an increased ratio of intracellular genomic to antigenomic viral RNA in TIAR-overexpressing cells, and confirmed preferential binding of TIAR to the 3' end of the WNV antigenome both in vitro and in infected cell extracts. We also demonstrated that multiple TIAR proteins can bind cooperatively to the WNV 3'(-) stem-loop RNA. These data provide supporting evidence for a model of TIAR-mediated rapid initiation of nascent genome RNA synthesis in infected cells.

TIAR

An Intrinsically Disordered RNA Binding Protein Modulates mRNA Translation and Storage.

Proteins with intrinsically disordered regions (IDR) play diverse functions in regulating gene expression in the cell. Many of these proteins interact with cytoplasmic ribosomes. However, the molecular functions related to the interactions are largely unclear. In this study, using an abundant RNA-binding protein, Sbp1, with a structurally well-defined RNA recognition motif and an intrinsically disordered RGG domain as a model system, we investigated how an RNA binding protein with IDR modulates mRNA storage and translation. Using genomic and molecular approaches, we show that Sbp1 slows ribosome movement on cellular mRNAs and promotes polysome stacking or aggregation. Sbp1-associated polysomes display a ring-shaped structure in addition to a beads-on-string morphology visualized under the electron microscope, likely to be an intermediate slow translation state between actively translating polysomes and the translation-sequestered RNA granule. Moreover, the binding of Sbp1 to the 5'UTRs of mRNAs represses both cap-dependent and cap-independent translation initiation of proteins, many are functionally important for general protein synthesis in the cell. Finally, post-translational modifications at the arginine in the RGG motif change the Sbp1 protein interactome and play important roles in directing cellular mRNAs to either translation or storage. Taken together, our study demonstrates that under physiological conditions, intrinsically disordered RNA binding proteins promote polysome aggregation and regulate mRNA translation and storage using multiple distinctive mechanisms. This research also establishes a framework with which functions of other IDR-containing proteins can be investigated and defined.

RNA-Binding Proteins

The DND1-NANOS3 complex shapes the primordial germ cell transcriptome via a heptanucleotide sequence in mRNA 3' UTRs.

The RNA-binding proteins DND1 and NANOS3 are essential for primordial germ cell survival1-5. Their co-immunoprecipitation and overlapping loss-of-function phenotypes suggest joint function6-8, yet how they co-regulate target mRNAs remains unclear. Here, we developed Tandem PAR-CLIP and identified a DND1-NANOS3 ribonucleoprotein that specifically recognizes an AUGAAUU heptanucleotide on target mRNAs, termed the NANOS3-dependent DND1 Recognition Element (N3-DRE). mRNAs containing 3'-UTR N3-DREs are aberrantly upregulated in DND1- or NANOS3-deficient germ cells and encode key cell-cycle and epigenome regulators, such as CDK1. Genome editing showed that the N3-DRE is essential for Cdk1 repression in mouse PGCs in vivo. A 1.7-Å crystal structure of the ternary complex of DND1, NANOS3, and CDK1-N3-DRE RNA revealed a continuous RNA-binding surface that confers high-affinity, sequence-specific recognition. Together, these findings define the molecular and functional basis of N3-DRE-mediated mRNA regulation in germ cell development. Moreover, we provide a paradigm of two RNA-binding proteins with low (DND1) or no (NANOS3) intrinsic sequence-specificity, jointly building a high-information-content RNA sequence motif that is different from the sum of their individual preferences. Because RNA-binding protein specificities are typically studied individually9-13, rather than in the context of ribonucleoproteins, this type of "two-factor authorization" may be an underappreciated mechanism to protect posttranscriptional gene regulatory networks from aberrant expression of an individual ribonucleoprotein component.

Journal Article

SUMOylation controls Hu antigen R posttranscriptional activity in liver cancer.

The posttranslational modification of proteins critically influences many biological processes and is a key mechanism that regulates the function of the RNA-binding protein Hu antigen R (HuR), a hub in liver cancer. Here, we show that HuR is SUMOylated in the tumor sections of patients with hepatocellular carcinoma in contrast to the surrounding tissue, as well as in human cell line and mouse models of the disease. SUMOylation of HuR promotes major cancer hallmarks, namely proliferation and invasion, whereas the absence of HuR SUMOylation results in a senescent phenotype with dysfunctional mitochondria and endoplasmic reticulum. Mechanistically, SUMOylation induces a structural rearrangement of the RNA recognition motifs that modulates HuR binding affinity to its target RNAs, further modifying the transcriptomic profile toward hepatic tumor progression. Overall, SUMOylation constitutes a mechanism of HuR regulation that could be potentially exploited as a therapeutic strategy for liver cancer.

Animals

Structural Features of DNA in TATA-Containing and TATA-Less Core Promoters of RNA Polymerase II Differ.

Nucleotide motifs in the core promoters of eukaryotic protein-coding genes transcribed by RNA polymerase II (Pol II) play an important role in the transcription process. We analyzed the role of an octanucleotide located in the TATA box position. Depending on whether this octanucleotide can form a complex with the TATA-binding protein (TBP), the promoter is classified as either TATA-containing or TATA-less. We analyzed the differences in the primary and spatial structures, as well as their dynamics, in TATA-containing and TATA-less promoters of mammals and plants. We divided the complete promoter sets of six organisms (H. sapiens, M. musculus, C. familiaris, A. thaliana, Z. mays, and H. vulgare) from the EPDnew database into TATA-containing and TATA-less fractions. The sizes of the TATA-containing promoter fractions are significantly smaller than those of the TATA-less fractions in all studied organisms, except in A. thaliana, where the sizes of both fractions are approximately equal. We characterized promoter architecture using variation profiles of various base-pair step parameters, minor-groove width, and the conformational dynamics of native DNA. The architectures of TATA-containing and TATA-less promoters differ significantly. The possible mechanistic influence of DNA structural features on the formation of the pre-initiation complex (PIC) in both types of promoters is discussed.

Promoter Regions, Genetic

Using the Tether Function Assay to Identify Potential Regulators of mRNA Translation and mRNA Decay.

RNA binding proteins (RBPs) and their associated partners are key factors of posttranscriptional control of gene expression. To study and manipulate the functional consequences of binding of these regulators to their targets, several tethering assays have been developed, in which a protein of interest is brought to a reporter mRNA through heterologous RNA-protein interaction motifs. The effect of such constrained binding is then monitored by measuring the accumulation of the reporter protein and mRNA. This chapter describes a protocol for the λN-BoxB tether system in transiently transfected mammalian cells. Combining the luciferase reporter technology to quantify protein amounts by light measurement and RNA amounts by RT-qPCR, this assay provides a simple and robust way to analyze the consequences of any protein binding in a controlled and defined manner.

RNA, Messenger

Genetic haplotypes in VWA8, OSBPL6, and ADAMTS9-AS2 are associated with immune-related adverse effects in ICI-treated patients with cancer.

BACKGROUND: Immune-related adverse events (irAEs) remain largely unpredictable, potentially affecting multiple organ systems and occurring at almost any point during and even occasionally after immune checkpoint inhibitor (ICI) treatment. To identify populations at risk for these immune-mediated toxicities, we analyzed genetic characteristics and immune markers associated with clinically significant irAEs. METHODS: We carried out a genome-wide association study on 373 white patients receiving ICI treatment. We identified single nucleotide polymorphisms associated with irAEs. Blood cytokine profiling and peripheral blood mononuclear cell RNA sequencing were performed at pretreatment baseline and 6-8 weeks after ICI initiation. Findings were validated in two external cohorts. RESULTS: We identified genetic haplotypes in VWA8 (Von Willebrand Factor A Domain Containing 8), OSBPL6 (Oxysterol Binding Protein Like 6), and ADAMTS9-AS2 (ADAM Metallopeptidase With Thrombospondin Type 1 Motif 9 Antisense RNA 2) associated with grade &#x2265;2 irAEs. Patients carrying risk haplotypes for one or more genes exhibited significantly greater rates of grade &#x2265;2 (OR 3.02; 95%&#x2009;CI 1.83 to 5.02; p<0.001), grade &#x2265;3 (OR 3.59; 95%&#x2009;CI 1.93 to 6.64; p<0.001), and multiple type irAE (OR 2.60; 95%&#x2009;CI 1.53 to 4.39; p<0.001). Serum CCL3 levels were significantly elevated in individuals carrying risk haplotypes (p=0.03). Gene expression analysis demonstrated activated autoimmune and inflammatory pathways in the genetic risk group. CONCLUSIONS: Novel polymorphisms in VWA8, OSBPL6, and ADAMTS9-AS2 may impact immune pathways, promote inflammation, potentiate autoimmune phenotypes, and convey risk of irAE in ICI-treated patients.

Humans

Genome-Wide Impact of Human DBR1 Depletion on RNA Processing Networks Reveal a Connection Between Pre-mRNA Splicing, mRNA Surveillance and Stress Granule Dynamics.

The RNA lariat debranching enzyme DBR1 is essential for intron turnover and RNA metabolism, yet its broader impact on transcriptome regulation remains incompletely defined. To elucidate the consequences of DBR1 depletion, we performed transcriptome-wide RNA sequencing of DBR1-knockdown and wild-type HEK293 cells. Differential expression analysis revealed widespread perturbations in pathways linked to RNA splicing, mRNA surveillance, translational control, and stress-granule biology. Many of the most significantly altered transcripts encode splicing factors and RNA quality-control components, underscoring DBR1's influence on post-transcriptional regulation. Alternative splicing analysis showed changes across multiple event types, with exon skipping accounting for >50% of events, followed by mutually exclusive exons, alternative 5' and 3' splice sites, and retained introns, indicating that DBR1 depletion induces pervasive splicing defects. Direct spliceosome inhibition using isoginkgetin (blocks tri-snRNP recruitment) and pladienolide B (targets SF3B1) reproduced the DBR1-KD mis-splicing patterns of cell signaling genes and factors involved in RNA metabolism, supporting a functional link between DBR1 activity and alternative splicing. Notably, DBR1 knockdown revealed a subset of transcripts that are both NMD-sensitive and enriched within stress granules. Consistent with this observation, G3BP1 immunopurification and confocal microscopy further support a role for DBR1 and UPF1 in stress-granule dynamics, suggesting that these factors may participate at distinct stages to influence mRNA fate under stress conditions. Together, these findings indicate that DBR1 functions beyond lariat RNA turnover as a common regulator of RNA processing, transcriptome stability, and stress granule homeostasis, revealing intricate crosstalk between RNA splicing and RNA quality control pathways in human cells.

Humans

Disruption of a six-nucleotide miRNA motif improves PKD1 dosage and ameliorates polycystic kidney disease.

Disrupting microRNA interactions to restore protein expression from haploinsufficient genes offers a promising precision-therapy strategy for monogenic disorders. PKD1 heterozygosity underlies autosomal dominant polycystic kidney disease (ADPKD), a disorder affecting nearly 12 million people worldwide, where reduced PKD1 dosage drives progressive cyst formation and kidney failure. We previously identified a 55-bp cis-repressive element in the PKD1 3'UTR. Here, we define a six-nucleotide miR-17 seed match within this element that is sufficient to reproduce PKD1 repression. In vivo base substitution of this motif stabilizes Pkd1 messenger RNA and increases polycystin-1 (PC1) protein levels, producing a robust reduction in cyst growth and preservation of kidney function in mouse models. To therapeutically recapitulate this effect, we developed a steric-blocking oligonucleotide that occludes the motif, stabilizes&#xa0;PKD1 transcript levels, increases PC1 expression, and mitigates cyst-pathogenic events in both murine and patient-derived ADPKD cells. Together, these findings establish a minimal, targetable cis-regulatory motif and provide proof of concept for oligonucleotide-mediated PKD1 derepression, while offering a potentially generalizable strategy to restore other haploinsufficient genes.

Animals

The structured mRNA element 45ABC mediates auto- and cross-regulation of RBP45 genes via alternative splicing.

Alternative splicing (AS) is a common gene regulatory mechanism involving distinct interactions between trans-acting factors and cis-regulatory elements on the precursor messenger RNA (pre-mRNA). In this study, we have functionally characterized the structured motif 45ABC, which is located in the pre-mRNAs of RNA-binding protein (RBP) 45 genes in many plant species. Our data revealed that this element mediates a negative auto- and cross-regulatory feedback loop via AS of the three 45ABC-containing RBP45 genes in Arabidopsis thaliana. We identified a G-rich stretch within the first stem as a potential RBP45 binding site and observed increased RBP45-dependent AS upon structural weakening of this pairing element. The second stem includes the alternative 5' splice site being activated in the presence of RBP45. Based on the known interaction between RBP45 homologs and U1 snRNP components required for 5' splice site recognition, we propose that RBP45 recruitment to stem I of 45ABC may induce usage of the alternative 5' splice site in stem II. The resulting splicing variant is unproductive, thereby diminishing RBP45 expression. Analysing the splicing-regulatory impact of the three At-RBP45 genes in auto- and cross-regulation and a transcriptome-wide manner revealed unequal genetic redundancy with a major role of RBP45B. Furthermore, phenotypical analysis of single- and higher-order rbp45 mutants pointed at these genes' functions in controlling primary root growth and flowering time. Taken together, we demonstrated that both sequence and structural features of 45ABC are critical for proper splicing control, balancing RBP45 expression and functions in plants via a conserved mRNA motif.

Alternative Splicing

Clinical outcomes and genomic features of uncommon EGFR exon 19 deletion subtypes in osimertinib-treated non-small cell lung cancer.

BACKGROUND: Epidermal growth factor receptor (EGFR) exon 19 deletion subtypes may be associated with differential survival outcomes following EGFR-tyrosine kinase inhibitor treatment. However, evidence remains scarce, particularly regarding osimertinib, and the underlying biological mechanisms are poorly understood. We aimed to compare survival outcomes among EGFR exon 19 deletion subtypes in patients with non-small cell lung cancer (NSCLC) treated with osimertinib. METHODS: In this multicenter retrospective study, patients with NSCLC were stratified according to exon 19 deletion subtypes. Whole-exome sequencing data from the American Association for Cancer Research Genomics Evidence Neoplasia Information Exchange registry and Memorial Sloan Kettering Clinicogenomic Harmonized Oncologic Real-World Dataset were analyzed to investigate co-occurring genomic alterations. RESULTS: Overall, 111 patients with advanced EGFR exon 19 deletion-positive NSCLC were analyzed and 86.5% received osimertinib as first-line therapy. Patients with non-E746_A750del (n&#xa0;=&#xa0;25) had shorter progression-free survival (PFS) than those with E746_A750del (n&#xa0;=&#xa0;86) (median: 14.3 vs. 20.6&#xa0;months; p&#xa0;<&#xa0;0.05). Among non-E746_A750del subtypes, L747_A750delinsP (n&#xa0;=&#xa0;4) had a particularly poor prognosis, with significantly worse survival than those with E746_A750del (median PFS: 3.5 vs. 20.6&#xa0;months; p&#xa0;<&#xa0;0.001, and median overall survival: 11.8 vs. 48.5&#xa0;months; p&#xa0;<&#xa0;0.001). In public database analyses, non-E746_A750del had a higher rate of RBM10 co-mutations, whereas L747_A750delinsP was characterized by frequent CDKN2A/B homozygous deletions and MYC amplifications. CONCLUSIONS: Non-E746_A750del was associated with poorer outcomes, with L747_A750delinsP potentially being a high-risk subtype. Differences in co-occurring genomic alterations may contribute to the prognostic heterogeneity among exon 19 deletion subtypes.

Humans

Machine learning analysis of the human initiator region reveals key features of different types of core promoters.

The initiator (Inr) is the starting point for the transcription of many genes. Here, we generated highly predictive machine learning models of the human Inr region, and determined that the Inr is present in &#x223c;60% of focused human promoters, identified a novel TATA-specific Inr, and detected the overlapping but functionally distinct TCT motif. Quantitative genome-wide analyses revealed a strict and synergistic interaction between the Inr and DPR, an inverse relationship between the TATA and DPR, a flexible and sometimes independent function of the TATA box in relation to the Inr, and different properties of the TCT motif in humans versus Drosophila.

Humans

Non-Coding c.*6C>T Variant in RBM8A Associated With Thrombocytopenia-Absent Radius (TAR) Syndrome in Three Indian Patients.

Thrombocytopenia-absent radius (TAR) syndrome is a rare genetic disorder characterized by the absence of radius in the forearms and a decrease in platelet count. The molecular basis of TAR syndrome is linked to a heterozygous minimal deletion within the 1q21.1 region spanning 200&#x2009;k bases (kb), resulting in a null allele and a nucleotide variation in RBM8A resulting in a hypomorphic allele. Previous studies have identified pathogenic variants in the coding regions of the RBM8A gene as the cause of TAR syndrome. However, the involvement of non-coding variants in disease pathogenesis remains largely unexplored. We investigated the association of a non-coding 3' UTR variant, c.*6C>T, in RBM8A with TAR syndrome in three individuals from two unrelated families of Indian origin. Our study provides evidence that this variant is associated with decreased stability of the transcript and is a hypomorphic allele with disease-causing impact when in trans with a null allele (1q21.1 deletion). The present work is the first application of an mRNA stability assay to directly detect RNA degradation in patients with non-coding RBM8A variants causing TAR syndrome.

Humans