snoRNA Expression Research Articles

SnoRNA box C/D levels in leukemia cells in chromosomal abnormalities after irradiation

The study objective. This paper reviews the express of C/D box snoRNAs (small nucleolar RNAs) and possibility of their use as biomarkers of radioresistance in chromosomal abnormalities. Material and Methods. The study compared the values of log2FC express of snoRNA C/Dbox in radiosensitive (HL-60) and radioresistant (K562) cell lines with different levels of chromosomal abnormalities. The cells were irradiated with X-ray radiation once at a dose of 4 Gy. The expression of snoRNA C/D was evaluated 1, 4 and 24 hours after irradiation, using new generation sequencing (NGS) MiSeq. Results. Different log2FC values were obtained in HL-60 and K562 cell lines 1 hour, 4 and 24 hours after irradiation. Positive expression of C/D snoRNA prevails in HL-60 throughout the experiment. In K562, the predominance of positive values of C/D snoRNA expression was observed 4 hours after irradiation, and negative values of log2FC were observed 24 hours later. the more anomalies there were in the chromosome, the greater the difference in expression we observed. at the same time, the number of C/D snoRNA changed maximally 24 hours after irradiation in the studied cell lines. We noted a greater number of C/D snoRNAs in the HL-60 cell line, and only 3 expressed C/D snoRNAs in the 15th marker chromosome in K562 out of 16 in HL-60 in the same chromosome. Conclusion. Our study showed a low informative value of using C/D snoRNAs family as markers of radiosensitivity in the presence of chromosomal abnormalities in cancer cells.

Small Nucleolar RNAs in Head and Neck Squamous Cell Carcinomas

Small nucleolar RNAs (snoRNAs), a distinct class of noncoding RNAs, encompass highly diverse structures and have a range of 60 to 300 nucleotides in length. About 90% of human snoRNAs are intronic and embedded within introns of their host gene transcripts. Most snoRNAs enriched in specific tissue correlate in abundance with their parental host genes. Advancements in high-throughput sequencing have facilitated the discovery of dysregulated snoRNA expression in numerous human malignancies including head and neck squamous cell carcinoma (HNSCC). Hundreds of differentially expressed snoRNAs have been identified in HNSCC tissues. Among 1,524 snoRNA genes in a 567 HNSCC cohort, 113 snoRNAs were found to be survival related. As for snoRNA’s roles in HNSCC, based on the available evidence, dysregulated snoRNAs are closely associated with the carcinogenesis and development of HNSCC. Upregulated snoRNAs have been shown to augment the expression of other oncogenes or activate the Wnt/β-catenin signaling pathway, thereby promoting tumor cell viability, glycolysis, migration, and the epithelial-mesenchymal transition while inhibiting apoptosis in vitro. In vivo animal studies have further elucidated the functional roles of snoRNAs. Knockdown of host genes of these snoRNAs suppressed the Wnt/β-catenin signaling pathway and restrained tumor proliferation and aggressiveness in mice. The putative mechanisms underlying these observations are associated with the biological functions of snoRNAs, primarily involving microRNA-like functions through the generation of microRNA-like fragments and regulation of alternative splicing to yield diverse transcripts. While most of the snoRNAs are upregulated in HNSCC, 4 downregulated snoRNAs have been identified and annotated. SNORA36B (implicated in the regulation of DNA templates) and U3 (chr17, influencing cell proliferation) may serve as protective factors associated with prolonged overall survival. This review describes the viable structures of snoRNAs, endeavors to refine snoRNA sequencing technology, and summarizes snoRNAs’ expression profile as well as their role in HNSCC progression for potential diagnostic and therapeutic strategies for HNSCC management.

Small nucleolar RNA expression profiles: A potential prognostic biomarker for non-viral Hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a challenging cancer with high mortality rates, limited predictability, and a lack of effective prognostic indicators. The relationship between small nucleolar RNAs (snoRNAs) and HCC is poorly understood. Based on the literature data, snoRNA studies were primarily focused on viral-related causes of HCC, such as Hepatitis B or C viruses (HBV or HCV). According to these studies, we selected four snoRNAs (snoRA12, snoRA47, snoRA80E, and snoRD126) for exploration in the context of non-viral-related causes, including non-alcoholic steatohepatitis (NASH), non-alcoholic fatty liver diseases (NAFLD), and alcohol steatohepatitis. The primary goal of this study was to gain a deeper understanding of how snoRNA expression affects patient outcomes and whether it can serve as a prognostic tool for non-viral HCC. We conducted a study on tissue samples from 35 HCC patients who had undergone resection at Pilsen University Hospital. SnoRA12, snoRA47, snoRA80E, and snoRD126 were studied by quantitative real-time PCR (qRT-PCR) in tumor and non-tumor adjacent tissue (NTAT) samples. Kaplan-Meier analysis was performed to assess the association of snoRNAs expression levels with patient outcomes: time to recurrence (TTR), disease-free survival (DFS) and overall survival (OS). In tumor tissues, snoRA12, snoRA47 and snoRA80E were upregulated, while snoRD-126 was downregulated compared to NTAT. Low expression of snoRA47 and snoRD126 in patients was associated with longer TTR and DFS. The individual expression of snoRA12 and snoRA80E did not show associations with TTR and DFS. However, a combination of medium expression of snoRD126 and snoRA80E was associated with longer TTR and DFS, while high and low expressions of the combined snoRA126 and snoRA80E showed no significant association with TTR, DFS, and OS. Conversely, a combination of high expression of snoRA12 and snoRD126 was associated with shorter TTR. In conclusion, the results indicate that snoRA47 and snoRD126 exhibit good prognostic power specifically for non-viral related HCC. Both snoRA47 and snoRD126 showed favorable prognostication in single and combined analysis when assessing patient outcomes. Also, in combination analysis, snoRA80E and snoRA12 showed favorable prognosis, but not alone.

SNORA69 is up-regulated in the lateral habenula of individuals with major depressive disorder

Major depressive disorder (MDD) is a complex and potentially debilitating illness whose etiology and pathology remains unclear. Non-coding RNAs have been implicated in MDD, where they display differential expression in the brain and the periphery. In this study, we quantified small nucleolar RNA (snoRNA) expression by small RNA sequencing in the lateral habenula (LHb) of individuals with MDD (n = 15) and psychiatrically-healthy controls (n = 15). We uncovered five snoRNAs that exhibited differential expression between MDD and controls (FDR < 0.01). Specifically, SNORA69 showed increased expression in MDD and was technically validated via RT-qPCR. We further investigated the expression of Snora69 in the LHb and peripheral blood of an unpredicted chronic mild stress (UCMS) mouse model of depression. Snora69 was specifically up-regulated in mice that underwent the UCMS paradigm. SNORA69 is known to guide pseudouridylation onto 5.8S and 18S rRNAs. We quantified the relative abundance of pseudouridines on 5.8S and 18S rRNA in human post-mortem LHb samples and found increased abundance of pseudouridines in the MDD group. Overall, our findings indicate the importance of brain snoRNAs in the pathology of MDD. Future studies characterizing SNORA69’s role in MDD pathology is warranted.

Abstract 5446: The role of snoRNAs in GBM cells, GSCs, neuronal precursor cells (NPCs), astrocytes, and normal brain tissues

Abstract rRNA modification are a crucial step in ribosome assembly and function. Small nucleolar RNAs select which nucleotides in rRNAs get modified. Typically, C/D box snoRNAs are implicated in 2’-O-ribose methylation (2’Omet) while H/ACA box snoRNAs are responsible for pseudo-uridylations. Alterations in snoRNA expression have been described in multiple tumor types while distinct snoRNAs have been linked to cancer-relevant phenotypes. Our initial study on snoRNA expression using a dedicated Ampliseq platform revealed a specific glioma stem cell (GSC) signature. We propose this snoRNA signature creates a unique rRNA modification pattern that shapes the ribosome, favoring the translation of genes in pathways critical for GSC growth and survival. We will expand our study and characterize the expression profile of snoRNAs and 2’Omethylation in a large panel of GBM cells, GSCs, neuronal precursor cells (NPCs), astrocytes, and normal brain tissues. Next, we will select snoRNAs displaying differential expression in GSCs and determine if changes in their levels affect proliferation, viability, response to temozolomide and radiation, and translation. We and others have observed that the integrity of protein complexes that regulate ribosomal biogenesis depends on PolyADP-ribosylation (PARylation)and PAR-binding. In agreement, genomic screenings determined that multiple genes regulating ribosome biogenesis confer sensitivity to PARP inhibitors. These findings offer a therapeutic opportunity. We will investigate the functional impact of PARylation on rRNA modification by determining the effect of PARP inhibitors on snoRNP assembly and 2’Omethylation. Finally, we will test the hypothesis that PARP and ribosome biogenesis inhibitor combinations would be more effective than PARP inhibition alone in treating GBM. Citation Format: Sujash Chatterjee, Scott Kuersten, Christina Middle, Morgan Roos, Pedro A. Galante, Gabriela Guardia, Luiz Penalva. The role of snoRNAs in GBM cells, GSCs, neuronal precursor cells (NPCs), astrocytes, and normal brain tissues [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5446.

Abstract 5581: The DACH1 gene, frequently co-deleted with BRCA2 in prostate cancer, governs PARP inhibitor resistance

Abstract Background: Prostate cancer (PCa), the second leading cause of death in American men, includes distinct genetic subtypes with distinct therapeutic vulnerabilities (1,2). The DACH1 gene, in the 13q21.31-q21.33 region, encodes a winged helix/Forkhead DNA-binding protein that governs cell-fate determination that is deleted in ~ 18% of human PCa, where it is associated with poor prognosis (3). Prostate-specific deletion of the Dach1 gene enhanced prostatic intraepithelial neoplasia (PIN). Methods: Analysis of DACH1 gene deletion and expression was conducted from public data bases and human prostate cancer samples. Cells derived from Dach1 gene deletion mice and human prostate cancer cell lines with DACH1 overexpression were analyzed for PARP inhibitor responses and mechanisms of PARPi resistance. Transgenic prostate Oncomice were generated in which the Dach1 gene was deleted in the prostate. Results: Herein, DACH1 was shown to be co-deleted with BRCA2 in each of 8 separate cohorts (N=2,186 patients), in ~3-12% of patients. Dach1 gene deletion or knockdown conferred PARP inhibitor resistance (talazoparib &amp;gt; niraparib &amp;gt; olaparib &amp;gt; rucaparib &amp;gt; veliparib). DACH1 enhanced PARP sensitivity through several mechanisms affecting replication stress, PARP1 binding, inhibiting G9a (reducing H3K9me2), inhibiting CHK1p and CDK1p and inducing expression of snoRNA, specifically the snoRNA known to bind PARP. PARP1 has a BRCT (BRCA1 C-terminus 1) homology domain governing PARP1 dimerization and binding to intact DNA in a complex within a nucleosome. DACH1 binding to PARP1 requires the BRCT domain. Conclusions: There is a correlation between DACH1a-/- and PARPi resistance, correlating with PARPi trapping ability. As reduced Dach1a expression may define a subclass of PCa that warrants specific therapies, testing for DACH1a may be warranted.

Effects of Eribulin on the RNA Content of Extracellular Vesicles Released by Metastatic Breast Cancer Cells.

Extracellular vesicles (EVs) are small lipid particles secreted by almost all human cells into the extracellular space. They perform the essential function of cell-to-cell communication, and their role in promoting breast cancer progression has been well demonstrated. It is known that EVs released by triple-negative and highly aggressive MDA-MB-231 breast cancer cells treated with paclitaxel, a microtubule-targeting agent (MTA), promoted chemoresistance in EV-recipient cells. Here, we studied the RNA content of EVs produced by the same MDA-MB-231 breast cancer cells treated with another MTA, eribulin mesylate. In particular, we analyzed the expression of different RNA species, including mRNAs, lncRNAs, miRNAs, snoRNAs, piRNAs and tRNA fragments by RNA-seq. Then, we performed differential expression analysis, weighted gene co-expression network analysis (WGCNA), functional enrichment analysis, and miRNA-target identification. Our findings demonstrate the possible involvement of EVs from eribulin-treated cells in the spread of chemoresistance, prompting the design of strategies that selectively target tumor EVs.

Small nucleolar RNA and its potential role in the oncogenesis and development of colorectal cancer.

Small nucleolar RNAs (snoRNAs) represent a class of non-coding RNAs that play pivotal roles in post-transcriptional RNA processing and modification, thereby contributing significantly to the maintenance of cellular functions related to protein synthesis. SnoRNAs have been discovered to possess the ability to influence cell fate and alter disease progression, holding immense potential in controlling human diseases. It is suggested that the dysregulation of snoRNAs in cancer exhibits differential expression across various cancer types, stages, metastasis, treatment response and/or prognosis in patients. On the other hand, colorectal cancer (CRC), a prevalent malignancy of the digestive system, is characterized by high incidence and mortality rates, ranking as the third most common cancer type. Recent research indicates that snoRNA dysregulation is associated with CRC, as snoRNA expression significantly differs between normal and cancerous conditions. Consequently, assessing snoRNA expression level and function holds promise for the prognosis and diagnosis of CRC. Nevertheless, current comprehension of the potential roles of snoRNAs in CRC remains limited. This review offers a comprehensive survey of the aberrant regulation of snoRNAs in CRC, providing valuable insights into the discovery of novel biomarkers, therapeutic targets, and potential tools for the diagnosis and treatment of CRC and furnishing critical cues for advancing research into CRC and the judicious selection of therapeutic targets.

How snoRNAs can contribute to cancer at multiple levels.

snoRNAs are a class of non-coding RNAs known to guide site specifically RNA modifications such as 2'-O-methylation and pseudouridylation. Recent results regarding snoRNA alterations in cancer has been made available and suggest their potential evaluation as diagnostic and prognostic biomarkers. A large part of these data, however, was not consistently confirmed and failed to provide mechanistic insights on the contribution of altered snoRNA expression to the neoplastic process. Here, we aim to critically review the available literature on snoRNA in cancer focusing on the studies elucidating the functional consequences of their deregulation. Beyond the canonical guide function in RNA processing and modification we also considered additional roles in which snoRNA, in various forms and through different modalities, are involved and that have been recently reported.

SNORA56-mediated pseudouridylation of 28 S rRNA inhibits ferroptosis and promotes colorectal cancer proliferation by enhancing GCLC translation

BackgroundColorectal cancer (CRC) is one of the most common malignancies and is characterized by reprogrammed metabolism. Ferroptosis, a programmed cell death dependent on iron, has emerged as a promising strategy for CRC treatment. Although small nucleolar RNAs are extensively involved in carcinogenesis, it is unclear if they regulate ferroptosis during CRC pathogenesis.MethodsThe dysregulated snoRNAs were identified using published sequencing data of CRC tissues. The expression of the candidate snoRNAs, host gene and target gene were assessed by real-time quantitative PCR (RT-qPCR), fluorescence in situ hybridization (FISH), immunohistochemistry (IHC) and western blots. The biological function of critical molecules was investigated using in vitro and in vivo strategies including Cell Counting Kit-8 (CCK8), colony formation assay, flow cytometry, Fe2+/Fe3+, GSH/GSSG and the xenograft mice models. The ribosomal activities were determined by polysome profiling and O-propargyl-puromycin (OP-Puro) assay. The proteomics was conducted to clarify the downstream targets and the underlying mechanisms were validated by IHC, Pearson correlation analysis, protein stability and rescue assays. The clinical significance of the snoRNA was explored using the Cox proportional hazard model, receiver operating characteristic (ROC) and survival analysis.ResultsHere, we investigated the SNORA56, which was elevated in CRC tissues and plasma, and correlated with CRC prognosis. SNORA56 deficiency in CRC impaired proliferation and triggered ferroptosis, resulting in reduced tumorigenesis. Mechanistically, SNORA56 mediated the pseudouridylation of 28 S rRNA at the U1664 site and promoted the translation of the catalytic subunit of glutamate cysteine ligase (GCLC), an indispensable rate-limiting enzyme in the biosynthesis of glutathione, which can inhibit ferroptosis by suppressing lipid peroxidation.ConclusionsTherefore, the SNORA56/28S rRNA/GCLC axis stimulates CRC progression by inhibiting the accumulation of cellular peroxides, and it may provide biomarker and therapeutic applications in CRC.

RAM is upregulated during T cell activation and is required for RNA cap formation and gene expression.

On T cell activation, upregulation of gene expression produces the protein required for the differentiation and proliferation of effector cell populations. RAM (RNMT-Activating Mini protein/RAMAC/Fam103a1), the cofactor of the RNA cap methyltransferase RNMT (RNA guanosine N-7 cap methyltransferase), is upregulated following activation. Formation of the RNA cap protects RNA during synthesis and guides RNA processing and translation. Using conditional gene deletion, we found that Ram expression stabilizes RNMT protein in T cells and is required for its upregulation on activation. When the Ram gene is deleted in naïve T cells, there are major impacts on activation-induced RNA cap formation and gene expression. Activated T cell proliferation is dependent on increased ribosome production; in Ram knockout T cells, activation-induced expression of ribosomal protein genes and snoRNAs is most severely reduced. Consistent with these changes, Ram deletion resulted in reduced protein synthesis, and reduced growth and proliferation of CD4 T cells. Deletion of Ram results in a similar but milder phenotype to Rnmt deletion, supporting the role of RAM as a RNMT cofactor.

Analysis of the snoRNA profile in ischemic and dilated cardiomyopathy

Abstract Introduction In last decade, knowledge of how non-coding RNAs (ncRNAs) contribute to the pathogenesis of cardiovascular disease has increased exponentially. However, other than miRNAs, relatively little is known about how other small RNAs specifically contribute to heart failure. snoRNAs have been known for decades, mainly for their role in biogenesis and ribosomal modification. Moreover, recent studies have provided fundamental information on how snoRNA regulated non-coding RNA expression. However, the contribution of these non-coding RNAs to human disease is a relatively new area of research, with heart failure being relatively unknown and understudied. Purpose We aimed to investigate whether snoRNA expression is regulated during heart failure from dilated (DCM) and ischemic (ICM) origin, and how its biogenesis is affected by the pathophysiology of the disease. Methods Heart tissue samples from ICM (n=22) and DCM (n=20) patients and control (CNT, n=8) subjects were analyzed by non-coding RNA-Sequencing (ncRNA-Seq) to evaluate transcriptome changes in snoRNA/scaRNA. In addition, through mRNA sequencing we analyzed the biogenesis pathway of these ncRNA in ICM (n=13) and DCM (n=13) patients compared to CNT (n=10). Microarray analysis was used to validate the alterations found in the snoRNA/scaRNA expression (ICM, n=24; DCM, n=20; CNT, n=10). Results A generalized alteration of the snoRNA biogenesis pathway was not observed, we only found NOLC1 underexpression in ICM patients (FC=-1.42, p&amp;lt;0.05). NOLC1 encodes a nucleolar protein that acts as a regulator of RNA polymerase I and connects RNA polymerase I with enzymes responsible for ribosomal processing and modification. However, ncRNA-Seq data showed altered profiles of snoRNA/scaRNA in ICM and DCM patients. We identified 24 differentially expressed snoRNAs in ICM and 35 in DCM, while only 3 scaRNAs in DCM patients. We highlight SNORD14C that was upregulated in DCM patients (FC=2.37, p&amp;lt;0.01) and we confirmed in the microarray analysis (FC=1.10, p&amp;lt;0.05). Moreover, SNORD116-18 was related to ejection fraction in ICM patients (r=0.460, p&amp;lt;0.05). Conclusion Our data indicate that there are changes in the expression of snoRNA and scaRNA with a specific profile for each etiology, ICM and DCM. However, a marked alteration in its biogenesis is not observed. Taken together and given the relationship of SNORD116-18 to ventricular function, our results offer a novel and promising insight into the differential involvement of these molecules in the pathophysiology of ICM and DCM.

PSVI-7 Snorna Dysregulated Expression and Potential Roles in Bovine Sub-Clinical Mastitis Due to Staphylococcus Chromogenes

Abstract Staphylococcus chromogenes (SC), a frequent non-aureus staphylococcus on Canadian herds causes both clinical and subclinical forms of mastitis and contributes to large economic losses on Canadian farms. However, little research attention has been directed to uncovering the molecular mechanisms underlying SC mastitis pathogenesis, including the roles of small nucleolar RNAs (snoRNAs). SnoRNAs function to regulate host ribosomal RNAs (rRNAs) biogenesis and processing, and are known to have regulatory functions in several human diseases, but no study has examined their regulatory functions in bovine mastitis. To understand the regulatory roles of snoRNAs in cows with SC subclinical mastitis, the snoRNA transcriptome of milk somatic cells from three SC infected cows [positive for SC only, have high somatic cell counts (SCC ≥350,000 cells/mL) for ≥ 3 months consecutively, only one positive udder sampled], and four healthy cows [low SCC (&amp;lt; 100,000 cells/mL) for ≥3 months consecutively, compositive sample of all quarters] was characterized by sequencing and bioinformatics analysis. Among 232 known snoRNAs found in the samples, 33 were differentially expressed (DE; 14 downregulated and 19 upregulated; FDR &amp;lt; 0.05). Out of these, SnoRA3/snoRA45 (upregulated) belongs to H/ACA snoRNA box type while SNORD14 (downregulated) belongs to C/D box snoRNA box type. According to RNAsnoop analysis, SnoRA3/snoRA45 interacted with 18S-1667 rRNA [minimum free energy (MFE) = -36Kcal/Mol] while SNORD14 interacted with 28S-3926 rRNA (MFE = -15.40Kcal/Mol). The observed strong MFE suggests that SnoRA3/snoRA45 and SNORD14 might potentially participate in rRNA modifications which could affect important functional sites of the ribosome with implications on the pathogenesis of bovine SC mastitis. SnoRA3/snoRA45 have been reported to guide site specific pseudouridylation of rRNA by upregulating the ribosomal pathway as well as have important roles in cell cycle progression in human. SNORD14 is expressed from the intron of its host gene RPS13, which is a ribosomal protein involved in protein biosynthesis. Also, SNORD14 has been shown to be potentially involved in intracellular protein transport and positive regulation of MAPK cascade. Our results suggest that the DE snoRNAs could potentially regulate the host rRNA biogenesis and processing in response to mastitis due to SC. To the best of our knowledge, this is the first study to report dysregulated snoRNA expression and potential involvement in bovine SC subclinical mastitis.

The Role of Small Nucleolar RNAs As Putative Biomarkers of Chemoresistance in Pediatric Acute Lymphoblastic Leukemia

Background Many previous studies have focused on the molecular landscape of pediatric acute lymphoblastic leukemia (ALL) with the aim to identify genetic changes related to disease development and outcome. However, the functional role of non-coding RNAs (ncRNAs) in leukemogenesis and treatment response is not fully understood. A group of ncRNAs known as small nucleolar RNAs (snoRNAs) regulates ribosomal biosynthesis, RNA splicing, and performs microRNA-like functions that affect post-translational gene expression. These functionalities can be dysregulated in cancer. The aim of this study was to explore the relationship between snoRNA expression and ex-vivo drug resistance in a cohort of pediatric ALL patients enrolled in the Nordic Society of Pediatric Hematology and Oncology (NOPHO) protocols. Methods We analyzed 119 B-ALL patients who were treated according to two consecutive NOPHO protocols (1992 and 2000). B-cells (CD19+) and T-cells (CD3+) from healthy blood donors were used as controls (n = 10). We stratified patients into low-, medium-, and high-resistance groups by ex-vivo drug screening using 10 commonly used chemotherapeutic drugs with the fluorometric microculture cytotoxicity assay (FMCA). RNA sequencing (RNA-seq) data were generated for all patients. Pairwise comparisons (Benjamini-Hochberg (BH) corrected Mann-Whitney U test) were conducted between the low and high resistance groups to detect differentially expressed genes. We selectively retained the differentially expressed snoRNAs for downstream analysis. BH corrected Kruskal-Wallis H and Mann-Whitney U tests were performed to compare the snoRNA expression levels for the three drug resistance groups, and between the ALL and control samples, respectively. Results We identified a set of 23 unique significantly upregulated snoRNAs (p-adjusted value &amp;lt; 0.05 and absolute log2FC&amp;gt;1) in the high-resistance group for one or multiple drugs: amsacrine (ams, n = 10), etoposide (eto, n = 10), tioguanine (thio, n = 8) and mitoxantrone (mito, n = 1). Among these genes, five snoRNAs ( SNORA30, SNORA33, SNORA36C, SNORA62 and SNORA66) were overexpressed in patients resistant to ams and eto, and one snoRNA ( SNORD27) in patients resistant to ams and mito. Gene annotation revealed 22 significantly differentially expressed snoRNAs residing within the intronic region of 20 host genes, either protein coding (including ribosomal genes) or long ncRNAs. Three snoRNAs ( SNORD22-eto, SNORD26-ams and SNORD27-ams and mito) arise from the same host gene ( SNHG1). Of the 23 differentially expressed snoRNAs, the majority (n = 18) were not differentially expressed between the ALL and control samples (BH corrected Mann-Whitney U test p-value ≥ 0.05). The expression of the host genes did not differ among the resistance groups (BH corrected Kruskal-Wallis H test p-value ≥ 0.05). However, we found that 14 of the host genes were differentially expressed between the ALL samples and controls (BH corrected Mann-Whitney U test p-value &amp;lt; 0.05). Conclusions This study is one of the first to focus on the role of snoRNAs and ex-vivo drug resistance in pediatric ALL. Our findings highlight substantial variations in snoRNA expression across the three resistance groups, underscoring the potential role of snoRNAs in modulating drug response. Importantly, our analysis indicates that the differential expression of snoRNAs in the resistance groups cannot be solely attributed to host gene expression, implying that targeting pathways involving host genes might not be the most effective approach. Rather than concentrating on pathways involving host genes, our results suggest that understanding the mechanisms of action of snoRNAs could provide promising avenues for developing novel therapeutic targets to enhance drug response in pediatric ALL.

Imprinted small nucleolar RNAs: Missing link in development and disease?

The 14q32.2 (DLK1-DIO3) and 15q11-q13 (SNURF-SNRPN) imprinted gene loci harbor the largest known small nucleolar RNA clusters expressed from the respective maternal and paternal alleles. Recent studies have demonstrated significant roles for the 15q11-q13 located SNORD115-SNORD116 C/D box snoRNAs in Prader-Willi syndrome (PWS), a neurodevelopmental disorder. Even though the effect of SNORD116 deletion is apparent in the PWS phenotype, similar effects of a SNORD113-SNORD114 cluster deletion from the 14q32.2 locus in Kagami-Ogata syndrome (KOS14) and upregulation in Temple syndrome (TS14) remain to be explored. Moreover, apart from their probable involvement in neurodevelopmental disorders, snoRNAs from the SNORD113-SNORD114 cluster have been implicated in multiple biological processes, including pluripotency, development, cancers, and RNA modifications. Here we summarize the current understanding of the system to explore the possibility of a link between developmental disorders and C/D box snoRNA expression from the imprinted 14q32.2 locus. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development RNA Processing > Processing of Small RNAs.

SnoRNAs in hematopoiesis and blood malignancies: A comprehensive review.

Small nucleolar RNAs (snoRNAs)are noncoding RNA molecules of highly variable size, usually ranging from 60 to 150 nucleotides. They are classified into H/ACA box snoRNAs, C/D box snoRNAs, and scaRNAs. Their functional profile includes biogenesis of ribosomes, processing of rRNAs, 2'-O-methylation and pseudouridylation of RNAs, alternative splicing and processing of mRNAs and the generation of small RNA molecules like miRNA. The snoRNAs have been observed to have an important role in hematopoiesis and malignant hematopoietic conditions including leukemia, lymphoma, and multiple myeloma. Blood malignancies arise in immune system cells or the bone marrow due to chromosome abnormalities. It has been estimated that annually over 1.25 million cases of blood cancer occur worldwide. The snoRNAs often show a differential expression profile in blood malignancies. Recent reports associate the abnormal expression of snoRNAs with the inhibition of apoptosis, uncontrolled cell proliferation, angiogenesis, and metastasis. This implies that targeting snoRNAs could be a potential way to treat hematologic malignancies. In this review, we describe the various functions of snoRNAs, their role in hematopoiesis, and the consequences of their dysregulation in blood malignancies. We also evaluate the potential of the dysregulated snoRNAs as biomarkers and therapeutic targets for blood malignancies.

SNORA71C promotes development and metastasis of breast cancer by regulating RUNX1 and ferroptosis.

SNORA71C promotes development and metastasis of breast cancer by regulating RUNX1 and ferroptosis.

The association of UBAP2L and G3BP1 mediated by small nucleolar RNA is essential for stress granule formation

Stress granules (SGs) are dynamic, non-membranous structures composed of non-translating mRNAs and various proteins and play critical roles in cell survival under stressed conditions. Extensive proteomics analyses have been performed to identify proteins in SGs; however, the molecular functions of these components in SG formation remain unclear. In this report, we show that ubiquitin-associated protein 2-like (UBAP2L) is a crucial component of SGs. UBAP2L localized to SGs in response to various stresses, and its depletion significantly suppressed SG organization. Proteomics and RNA sequencing analyses found that UBAP2L formed a protein-RNA complex with Ras-GTP-activating protein SH3 domain binding protein 1 (G3BP1) and small nucleolar RNAs (snoRNAs). In vitro binding analysis demonstrated that snoRNAs were required for UBAP2L association with G3BP1. In addition, decreased expression of snoRNAs reduced the interaction between UBAP2L and G3BP1 and suppressed SG formation. Our results reveal a critical role of SG component, the UBAP2L/snoRNA/G3BP1 protein-RNA complex, and provide new insights into the regulation of SG assembly.

Motif conservation, stability, and host gene expression are the main drivers of snoRNA expression across vertebrates

Small nucleolar RNAs (snoRNAs) are structured noncoding RNAs present in multiple copies within eukaryotic genomes. snoRNAs guide chemical modifications on their target RNA and regulate processes like ribosome assembly and splicing. Most human snoRNAs are embedded within host gene introns, the remainder being independently expressed from intergenic regions. We recently characterized the abundance of snoRNAs and their host gene across several healthy human tissues and found that the level of most snoRNAs does not correlate with that of their host gene, with the observation that snoRNAs embedded within the same host gene often differ drastically in abundance. To better understand the determinants of snoRNA expression, we trained machine learning models to predict whether snoRNAs are expressed or not in human tissues based on more than 30 collected features related to snoRNAs and their genomic context. By interpreting the models' predictions, we find that snoRNAs rely on conserved motifs, a stable global structure and terminal stem, and a transcribed locus to be expressed. We observe that these features explain well the varying abundance of snoRNAs embedded within the same host gene. By predicting the expression status of snoRNAs across several vertebrates, we notice that only one-third of all annotated snoRNAs are expressed per genome, as in humans. Our results suggest that ancestral snoRNAs disseminated within vertebrate genomes, sometimes leading to the development of new functions and a probable gain in fitness and thereby conserving features favorable to the expression of these few snoRNAs, the large remainder often degenerating into pseudogenes.

Tumor-educated platelet SNORA58, SNORA68 and SNORD93 as novel diagnostic biomarkers for esophageal cancer.

Aim: The purpose of this study was to evaluate whether tumor-educated platelet (TEP) snoRNAs could be used as a diagnostic biomarker for esophageal cancer (ESCA). Methods: Platelet precipitates were obtained from platelet-rich plasma by low-speed centrifugation, and total RNA was extracted from platelets using Trizol™ reagent. RT-qPCR was used to detect snoRNA expression, and the receiver operating characteristic was used to assess its diagnostic potential. Results: SNORA58, SNORA68 and SNORD93 were significantly upregulated in TEPs from ESCA patients and early-stage patients compared with healthy controls. Importantly, the three snoRNAs were capable of serving as circulating biomarkers of diagnostics and early diagnosis of ESCA, possessing areas under the curveof 0.846and 0.857, respectively. Conclusion: TEP SNORA58, SNORA68 and SNORD93 could potentially serve as noninvasive biomarkers fordiagnosisand early diagnosis of ESCA.