The regulatory roles of small nucleolar RNAs within their host locus.

Small nucleolar RNAs (snoRNAs) are a class of conserved noncoding RNAs forming complexes with proteins to catalyse site-specific modifications on ribosomal RNA. Besides this canonical role, several snoRNAs are now known to regulate diverse levels of gene expression. While these functions are carried out in trans by mature snoRNAs, evidence has also been emerging of regulatory roles of snoRNAs in cis, either within their genomic locus or as longer transcription intermediates during their maturation. Herein, we review recent findings that snoRNAs can interact in cis with their intron to regulate the expression of their host gene. We also explore the ever-growing diversity of longer host-derived snoRNA extensions and their functional impact across the transcriptome. Finally, we discuss the role of snoRNA duplications into forging these new layers of snoRNA-mediated regulation, as well as their involvement in the genomic imprinting of their host locus.

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.

HMGB1 prefers to interact with structural RNAs and regulates rRNA methylation modification and translation in HeLa cells.

BACKGROUND: High-mobility group B1 (HMGB1) is both a DNA binding nuclear factor modulating transcription and a crucial cytokine that mediates the response to both infectious and noninfectious inflammation such as autoimmunity, cancer, trauma, and ischemia reperfusion injury. HMGB1 has been proposed to control ribosome biogenesis, similar as the other members of a class of HMGB proteins. RESULTS: Here, we report that HMGB1 selectively promotes transcription of genes involved in the regulation of transcription, osteoclast differentiation and apoptotic process. Improved RNA immunoprecipitation by UV cross-linking and deep sequencing (iRIP-seq) experiment revealed that HMGB1 selectively bound to mRNAs functioning not only in signal transduction and gene expression, but also in axon guidance, focal adhesion, and extracellular matrix organization. Importantly, HMGB1-bound reads were strongly enriched in specific structured RNAs, including the domain II of 28S rRNA, H/ACA box snoRNAs including snoRNA63 and scaRNAs. RTL-P experiment showed that overexpression of HMGB1 led to a decreased methylation modification of 28S rRNA at position Am2388, Cm2409, and Gm2411. We further showed that HMGB1 overexpression increased ribosome RNA expression levels and enhanced protein synthesis. CONCLUSION: Taken together, our results support a model in which HMGB1 binds to multiple RNA species in human cancer cells, which could at least partially contribute to HMGB1-modulated rRNA modification, protein synthesis function of ribosomes, and differential gene expression including rRNA genes. These findings provide additional mechanistic clues to HMGB1 functions in cancers and cell differentiation.

NAP-seq reveals multiple classes of structured noncoding RNAs with regulatory functions.

Up to 80% of the human genome produces "dark matter" RNAs, most of which are noncapped RNAs (napRNAs) that frequently act as noncoding RNAs (ncRNAs) to modulate gene expression. Here, by developing a method, NAP-seq, to globally profile the full-length sequences of napRNAs with various terminal modifications at single-nucleotide resolution, we reveal diverse classes of structured ncRNAs. We discover stably expressed linear intron RNAs (sliRNAs), a class of snoRNA-intron RNAs (snotrons), a class of RNAs embedded in miRNA spacers (misRNAs) and thousands of previously uncharacterized structured napRNAs in humans and mice. These napRNAs undergo dynamic changes in response to various stimuli and differentiation stages. Importantly, we show that a structured napRNA regulates myoblast differentiation and a napRNA DINAP interacts with dyskerin pseudouridine synthase 1 (DKC1) to promote cell proliferation by maintaining DKC1 protein stability. Our approach establishes a paradigm for discovering various classes of ncRNAs with regulatory functions.

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.

Comprehensive map of ribosomal 2'-O-methylation and C/D box snoRNAs in Drosophila melanogaster.

During their maturation, ribosomal RNAs (rRNAs) are decorated by hundreds of chemical modifications that participate in proper folding of rRNA secondary structures and therefore in ribosomal function. Along with pseudouridine, methylation of the 2'-hydroxyl ribose moiety (Nm) is the most abundant modification of rRNAs. The majority of Nm modifications in eukaryotes are placed by Fibrillarin, a conserved methyltransferase belonging to a ribonucleoprotein complex guided by C/D box small nucleolar RNAs (C/D box snoRNAs). These modifications impact interactions between rRNAs, tRNAs and mRNAs, and some are known to fine tune translation rates and efficiency. In this study, we built the first comprehensive map of Nm sites in Drosophila melanogaster rRNAs using two complementary approaches (RiboMethSeq and Nanopore direct RNA sequencing) and identified their corresponding C/D box snoRNAs by whole-transcriptome sequencing. We de novo identified 61 Nm sites, from which 55 are supported by both sequencing methods, we validated the expression of 106 C/D box snoRNAs and we predicted new or alternative rRNA Nm targets for 31 of them. Comparison of methylation level upon different stresses show only slight but specific variations, indicating that this modification is relatively stable in D. melanogaster. This study paves the way to investigate the impact of snoRNA-mediated 2'-O-methylation on translation and proteostasis in a whole organism.

GPATCH4 regulates rRNA and snRNA 2'-O-methylation in both DHX15-dependent and DHX15-independent manners.

Regulation of RNA helicase activity, often accomplished by protein cofactors, is essential to ensure target specificity within the complex cellular environment. The largest family of RNA helicase cofactors are the G-patch proteins, but the cognate RNA helicases and cellular functions of numerous human G-patch proteins remain elusive. Here, we discover that GPATCH4 is a stimulatory cofactor of DHX15 that interacts with the DEAH box helicase in the nucleolus via residues in its G-patch domain. We reveal that GPATCH4 associates with pre-ribosomal particles, and crosslinks to the transcribed ribosomal DNA locus and precursor ribosomal RNAs as well as binding to small nucleolar- and small Cajal body-associated RNAs that guide rRNA and snRNA modifications. Loss of GPATCH4 impairs 2'-O-methylation at various rRNA and snRNA sites leading to decreased protein synthesis and cell growth. We demonstrate that the regulation of 2'-O-methylation by GPATCH4 is both dependent on, and independent of, its interaction with DHX15. Intriguingly, the ATPase activity of DHX15 is necessary for efficient methylation of DHX15-dependent sites, suggesting a function of DHX15 in regulating snoRNA-guided 2'-O-methylation of rRNA that requires activation by GPATCH4. Overall, our findings extend knowledge on RNA helicase regulation by G-patch proteins and also provide important new insights into the mechanisms regulating installation of rRNA and snRNA modifications, which are essential for ribosome function and pre-mRNA splicing.

Intron Editing Reveals SNORD-Dependent Maturation of the Small Nucleolar RNA Host Gene GAS5 in Human Cells.

The GAS5 gene encodes a long non-coding RNA (lncRNA) and intron-located small nucleolar RNAs (snoRNAs). Its structure, splice variants, and diverse functions in mammalian cells have been thoroughly investigated. However, there are still no data on a successful knockout of GAS5 in human cells, with most of the loss-of-function experiments utilizing standard techniques to produce knockdowns. By using CRISPR/Cas9 to introduce double-strand breaks in the terminal intronic box C/D snoRNA genes (SNORDs), we created monoclonal cell lines carrying continuous deletions in one of the GAS5 alleles. The levels of GAS5-encoded box C/D snoRNAs and lncRNA GAS5 were assessed, and the formation of the novel splice variants was analyzed. To comprehensively evaluate the influence of specific SNORD mutations, human cell lines with individual mutations in SNORD74 and SNORD81 were obtained. Specific mutations in SNORD74 led to the downregulation of all GAS5-encoded SNORDs and GAS5 lncRNA. Further analysis revealed that SNORD74 contains a specific regulatory element modulating the maturation of the GAS5 precursor transcript. The results demonstrate that the maturation of GAS5 occurs through the m6A-associated pathway in a SNORD-dependent manner, which is a quite intriguing epitranscriptomic mechanism.

A single pseudouridine on rRNA regulates ribosome structure and function in the mammalian parasite Trypanosoma brucei.

Trypanosomes are protozoan parasites that cycle between insect and mammalian hosts and are the causative agent of sleeping sickness. Here, we describe the changes of pseudouridine (Ψ) modification on rRNA in the two life stages of the parasite using four different genome-wide approaches. CRISPR-Cas9 knock-outs of all four snoRNAs guiding Ψ on helix 69 (H69) of the large rRNA subunit were lethal. A single knock-out of a snoRNA guiding Ψ530 on H69 altered the composition of the 80S monosome. These changes specifically affected the translation of only a subset of proteins. This study correlates a single site Ψ modification with changes in ribosomal protein stoichiometry, supported by a high-resolution cryo-EM structure. We propose that alteration in rRNA modifications could generate ribosomes preferentially translating state-beneficial proteins.

A prognostic signature based on snoRNA predicts the overall survival of lower-grade glioma patients.

Introduction: Small nucleolar RNAs (snoRNAs) are a group of non-coding RNAs enriched in the nucleus which direct post-transcriptional modifications of rRNAs, snRNAs and other molecules. Recent studies have suggested that snoRNAs have a significant role in tumor oncogenesis and can be served as prognostic markers for predicting the overall survival of tumor patients. Methods: We screened 122 survival-related snoRNAs from public databases and eventually selected 7 snoRNAs that were most relevant to the prognosis of lower-grade glioma (LGG) patients for the establishment of the 7-snoRNA prognostic signature. Further, we combined clinical characteristics related to the prognosis of glioma patients and the 7-snoRNA prognostic signature to construct a nomogram. Results: The prognostic model displayed greater predictive power in both validation set and stratification analysis. Results of enrichment analysis revealed that these snoRNAs mainly participated in the post-transcriptional process such as RNA splicing, metabolism and modifications. In addition, 7-snoRNA prognostic signature were positively correlated with immune scores and expression levels of multiple immune checkpoint molecules, which can be used as potential biomarkers for immunotherapy prediction. From the results of bioinformatics analysis, we inferred that SNORD88C has a major role in the development of glioma, and then performed in vitro experiments to validate it. The results revealed that SNORD88C could promote the proliferation, invasion and migration of glioma cells. Discussion: We established a 7-snoRNA prognostic signature and nomogram that can be applied to evaluate the survival of LGG patients with good sensitivity and specificity. In addition, SNORD88C could promote the proliferation, migration and invasion of glioma cells and is involved in a variety of biological processes related to DNA and RNA.

Maturation of small nucleolar RNAs: from production to function.

Small Nucleolar RNAs (snoRNAs) are an abundant group of non-coding RNAs with well-defined roles in ribosomal RNA processing, folding and chemical modification. Besides their classic roles in ribosome biogenesis, snoRNAs are also implicated in several other cellular activities including regulation of splicing, transcription, RNA editing, cellular trafficking, and miRNA-like functions. Mature snoRNAs must undergo a series of processing steps tightly regulated by transiently associating factors and coordinated with other cellular processes including transcription and splicing. In addition to their mature forms, snoRNAs can contribute to gene expression regulation through their derivatives and degradation products. Here, we review the current knowledge on mechanisms of snoRNA maturation, including the different pathways of processing, and the regulatory mechanisms that control snoRNA levels and complex assembly. We also discuss the significance of studying snoRNA maturation, highlight the gaps in the current knowledge and suggest directions for future research in this area.

A snoRNA-tRNA modification network governs codon-biased cellular states.

The dynamic balance between tRNA supply and codon usage demand is a fundamental principle in the cellular translation economy. However, the regulation and functional consequences of this balance remain unclear. Here, we use PARIS2 interactome capture, structure modeling, conservation analysis, RNA-protein interaction analysis, and modification mapping to reveal the targets of hundreds of snoRNAs, many of which were previously considered orphans. We identify a snoRNA-tRNA interaction network that is required for global tRNA modifications, including 2'-O-methylation and others. Loss of Fibrillarin, the snoRNA-guided 2'-O-methyltransferase, induces global upregulation of tRNA fragments, a large group of regulatory RNAs. In particular, the snoRNAs D97/D133 guide the 2'-O-methylation of multiple tRNAs, especially for the amino acid methionine (Met), a protein-intrinsic antioxidant. Loss of D97/D133 snoRNAs in human HEK293 cells reduced target tRNA levels and induced codon adaptation of the transcriptome and translatome. Both single and double knockouts of D97 and D133 in HEK293 cells suppress Met-enriched proliferation-related gene expression programs, including, translation, splicing, and mitochondrial energy metabolism, and promote Met-depleted programs related to development, differentiation, and morphogenesis. In a mouse embryonic stem cell model of development, knockdown and knockout of D97/D133 promote differentiation to mesoderm and endoderm fates, such as cardiomyocytes, without compromising pluripotency, consistent with the enhanced development-related gene expression programs in human cells. This work solves a decades-old mystery about orphan snoRNAs and reveals a function of snoRNAs in controlling the codon-biased dichotomous cellular states of proliferation and development.

What is the Role of SNORA42 in Carcinogenesis? A Systematic Review.

OBJECTIVE: Perform a systematic literature review on SNORA42 in carcinogenesis in order to elucidate its importance, its potential use as a biomarker and as a therapeutic target. METHODS: Using PubMed, SciELO and Science Direct databases as search means, articles that are in line with the scope of the study, written in English, that were published between 2012 and 2022, were selected using the following keywords: "small nucleolar RNA 42", "snoRNA 42" and "SNORA42", as well as searches for the synonyms of this snoRNA (SNORA80E, box H/ACA 42 and ACA42). RESULT: From a total of 131 studies, seven were selected, in which it was possible to identify that SNORA42 interferes in several biological processes, such as proliferation, migration, invasion, metastasis, apoptosis, and signaling pathways. Among the signaling pathways, the p53 and NF-KappaB pathways stand out. Moreover, it is a potential biomarker for diagnosis, prognosis, and treatment of cancer. CONCLUSION: The summary of the main information about SNORA42 in the process of carcinogenesis and cancer progression shows that the use of this snoRNA is ideal for future applications in the field of oncology, in which it can be used as a biomarker and therapeutic target. Thus, it is of fundamental importance to carry out new studies to consolidate the applicability of this molecule.

Intronic small nucleolar RNAs regulate host gene splicing through base pairing with their adjacent intronic sequences.

BACKGROUND: Small nucleolar RNAs (snoRNAs) are abundant noncoding RNAs best known for their involvement in ribosomal RNA maturation. In mammals, most expressed snoRNAs are embedded in introns of longer genes and produced through transcription and splicing of their host. Intronic snoRNAs were long viewed as inert passengers with little effect on host expression. However, a recent study reported a snoRNA influencing the splicing and ultimate output of its host gene. Overall, the general contribution of intronic snoRNAs to host expression remains unclear. RESULTS: Computational analysis of large-scale human RNA-RNA interaction datasets indicates that 30% of detected snoRNAs interact with their host transcripts. Many snoRNA-host duplexes are located near alternatively spliced exons and display high sequence conservation suggesting a possible role in splicing regulation. The study of the model SNORD2-EIF4A2 duplex indicates that the snoRNA interaction with the host intronic sequence conceals the branch point leading to decreased inclusion of the adjacent alternative exon. Extended SNORD2 sequence containing the interacting intronic region accumulates in sequencing datasets in a cell-type-specific manner. Antisense oligonucleotides and mutations that disrupt the formation of the snoRNA-intron structure promote the splicing of the alternative exon, shifting the EIF4A2 transcript ratio away from nonsense-mediated decay. CONCLUSIONS: Many snoRNAs form RNA duplexes near alternative exons of their host transcripts, placing them in optimal positions to control host output as shown for the SNORD2-EIF4A2 model system. Overall, our study supports a more widespread role for intronic snoRNAs in the regulation of their host transcript maturation.

The fission yeast methyl phosphate capping enzyme Bmc1 guides 2'-O-methylation of the U6 snRNA.

Splicing requires the tight coordination of dynamic spliceosomal RNAs and proteins. U6 is the only spliceosomal RNA transcribed by RNA Polymerase III and undergoes an extensive maturation process. In humans and fission yeast, this includes addition of a 5' γ-monomethyl phosphate cap by members of the Bin3/MePCE family as well as snoRNA guided 2'-O-methylation. Previously, we have shown that the Bin3/MePCE homolog Bmc1 is recruited to the S. pombe telomerase holoenzyme by the LARP7 family protein Pof8, where it acts in a catalytic-independent manner to protect the telomerase RNA and facilitate holoenzyme assembly. Here, we show that Bmc1 and Pof8 are required for the formation of a distinct U6 snRNP that promotes 2'-O-methylation of U6, and identify a non-canonical snoRNA that guides this methylation. We also show that the 5' γ-monomethyl phosphate capping activity of Bmc1 is not required for its role in promoting snoRNA guided 2'-O-methylation, and that this role relies on different regions of Pof8 from those required for Pof8 function in telomerase. Our results are consistent with a novel role for Bmc1/MePCE family members in stimulating 2'-O-methylation and a more general role for Bmc1 and Pof8 in guiding noncoding RNP assembly beyond the telomerase RNP.

Alternative Splicing of lncRNAs From SNHG Family Alters snoRNA Expression and Induces Chemoresistance in Hepatoblastoma.

BACKGROUND & AIMS: Hepatoblastoma (HB) is a common pediatric malignant liver tumor that is characterized by a low level of genetic mutations. Alternative splicing (AS) has been shown to be closely associated with cancer progression, especially in tumors with a low mutational burden. However, the role of AS in HB remains unknown. METHODS: Transcriptome sequencing was performed on 5 pairs of HB tissues and matched non-tumor tissues to delineate the AS landscape in HB. AS events were validated in 92 samples from 46 patients. RNA pull-down and RNA immunoprecipitation assays were carried out to identify splicing factors that regulate the AS of small nucleolar RNA host genes (SNHG). Patient-derived organoids (PDOs) were established to investigate the role of the splicing factor polyadenylate-binding nuclear protein 1 (PABPN1). RESULTS: This study uncovered aberrant alternative splicing in HB, including lncRNAs from SNHG family that undergo intron retention in HB. Further investigations revealed that PABPN1, a significantly upregulated RNA binding protein, interacts with splicing machinery in HB, inducing the intron retention of these SNHG RNAs and the downregulation of intronic small nucleolar RNAs (snoRNAs). Functionally, PABPN1 acts as an oncofetal splicing regulator in HB by promoting cell proliferation and DNA damage repair via inducing the intron retention of SNHG19. Knock-down of PABPN1 increases the cisplatin sensitivity of HB PDOs. CONCLUSIONS: Our findings revealed the role of intron retention in regulating snoRNA expression in hepatoblastoma, explained detailed regulatory mechanism between PABPN1 and the intron retention of SNHG RNAs, and provided insight into the development of new HB treatment options.

Molecular mechanisms of snoRNA-IL-15 crosstalk in adipocyte lipolysis and NK cell rejuvenation.

Obesity, in which the functional importance of small nucleolar RNAs (snoRNAs) remains elusive, correlates with risk for many cancer types. Here, we identify that the serum copies of adipocyte-expressed SNORD46 correlate with body mass index (BMI), and serum SNORD46 antagonizes interleukin-15 (IL-15) signaling. Mechanically, SNORD46 binds IL-15 via G11, and G11A (a mutation that significantly enhances binding affinity) knockin drives obesity in mice. Functionally, SNORD46 blocks IL-15-induced, FER kinase-dependent phosphorylation of platelet glycoprotein 4 (CD36) and monoglyceride lipase (MGLL) in adipocytes, leading to inhibited lipolysis and browning. In natural killer (NK) cells, SNORD46 suppresses the IL-15-dependent autophagy, leading to reduced viability of obese NK. SNORD46 power inhibitors exhibit anti-obesity effects, concurring with improved viability of obese NK and anti-tumor immunity of CAR-NK cell therapy. Hence, our findings demonstrate the functional importance of snoRNAs in obesity and the utility of snoRNA power inhibitors for antagonizing obesity-associated immune resistance.

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.

SnoRNA and lncSNHG: Advances of nucleolar small RNA host gene transcripts in anti-tumor immunity.

The small nucleolar RNA host genes (SNHGs) are a group of genes that can be transcript into long non-coding RNA SNHG (lncSNHG) and further processed into small nucleolar RNAs (snoRNAs). Although lncSNHGs and snoRNAs are well established to play pivotal roles in tumorigenesis, how lncSNHGs and snoRNAs regulate the immune cell behavior and function to mediate anti-tumor immunity remains further illustrated. Certain immune cell types carry out distinct roles to participate in each step of tumorigenesis. It is particularly important to understand how lncSNHGs and snoRNAs regulate the immune cell function to manipulate anti-tumor immunity. Here, we discuss the expression, mechanism of action, and potential clinical relevance of lncSNHGs and snoRNAs in regulating different types of immune cells that are closely related to anti-tumor immunity. By uncovering the changes and roles of lncSNHGs and snoRNAs in different immune cells, we aim to provide a better understanding of how the transcripts of SNHGs participate in tumorigenesis from an immune perspective.

U3 snoRNA-mediated degradation of ZBTB7A regulates aerobic glycolysis in isocitrate dehydrogenase 1 wild-type glioblastoma cells.

AIMS: The isocitrate dehydrogenase (IDH) phenotype is associated with reprogrammed energy metabolism in glioblastoma (GBM) cells. Small nucleolar RNAs (snoRNAs) are known to exert an important regulatory role in the energy metabolism of tumor cells. The purpose of this study was to investigate the role of C/D box snoRNA U3 and transcription factor zinc finger and BTB domain-containing 7A (ZBTB7A) in the regulation of aerobic glycolysis and the proliferative capacity of IDH1 wild-type (IDH1WT ) GBM cells. METHODS: Quantitative reverse transcription PCR and western blot assays were utilized to detect snoRNA U3 and ZBTB7A expression. U3 promoter methylation status was analyzed via bisulfite sequencing and methylation-specific PCR. Seahorse XF glycolysis stress assays, lactate production and glucose consumption measurement assays, and cell viability assays were utilized to detect glycolysis and proliferation of IDH1WT GBM cells. RESULTS: We found that hypomethylation of the CpG island in the promoter region of U3 led to the upregulation of U3 expression in IDH1WT GBM cells, and the knockdown of U3 suppressed aerobic glycolysis and the proliferation ability of IDH1WT GBM cells. We found that small nucleolar-derived RNA (sdRNA) U3-miR, a small fragment produced by U3, was able to bind to the ZBTB4 3'UTR region and reduce ZBTB7A mRNA stability, thereby downregulating ZBTB7A protein expression. Furthermore, ZBTB7A transcriptionally inhibited the expression of hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA), which are key enzymes of aerobic glycolysis, by directly binding to the HK2 and LDHA promoter regions, thereby forming the U3/ZBTB7A/HK2 LDHA pathway that regulates aerobic glycolysis and proliferation of IDH1WT GBM cells. CONCLUSION: U3 enhances aerobic glycolysis and proliferation in IDH1WT GBM cells via the U3/ZBTB7A/HK2 LDHA axis.