SNORA69 is up-regulated in the lateral habenula of individuals with major depressive disorder
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ABSTRACT: 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, and the first study to investigate snoRNA expression in MDD. Future studies characterizing SNORA69’s role in MDD pathology is warranted.
Project description:Ribosome biosynthesis plays a crucial role in regulating protein translation and is essential for cell growth and development in physiological progress. The progression and recurrence of Pterygia mainly occur due to the abnormal proliferation and migration of stromal Pterygia fibroblasts. Small nucleolar RNA U3 (U3 snoRNA), harboring the atypical C/D boxes, is involved in 18S ribosomal RNA (18S rRNA) synthesis; however, the mechanism of U3 snoRNA in Pterygia remains unclear. Methods: Primary HCFs and HPFs were separated and cultured from fresh conjunctival grafts and Pterygia tissues. The PLKO.1 lentiviral system and CRISPR/Cas9 recombinant construct were, respectively, used to overexpress and silence U3 snoRNA in HPF and HCF cells for further specific phenotypes analysis. RNA-seq and TMT-labeled quantitative protein mass spectrometry were utilized to evaluate the effect of U3 snoRNA on mRNA transcripts and protein synthesis. Results: Reduced U3 snoRNA in Pterygia promotes HCF or HPF cells' proliferation, migration, and cell cycle but has no significant effect on apoptosis. U3 snoRNA modulates 18S rRNA synthesis through shearing precursor ribosomal RNA 47S rRNA at the 5′ external transcribed spacer (5′ ETS). Moreover, the altered U3 snoRNA causes mRNA and protein differential expression in HCF or HPF cells. Conclusion: The atypical U3 snoRNA regulates the translation of specific proteins to exert a suppressive function in Pterygia through modulating the 18S RNA synthesis. Here, we uncover a novel insight into U3 snoRNA biology in the development of Pterygia.
Project description:Non-coding RNAs including small nucleolar RNAs (snoRNAs) play important roles in leukemogenesis but the relevant mechanisms remain incompletely understood. We performed snoRNA focused CRISPR-Cas9 knockout library screenings which targeted the entire snoRNAnome and corresponding host genes. The C/D box containing SNORD42A was identified as an essential modulator for AML cell survival and proliferation in multiple human leukemia cell lines. In line, SNORD42A was consistently expressed at high levels in primary AML patient samples. Functionally, knockout of SNORD42A reduced colony formation capability and inhibited proliferation. The SNORD42A acts as a C/D box snoRNA and directs 2´-O-methylation at Uridine 116 of 18S rRNA. Deletion of SNORD42A decreased 18S-U116 2´-O-methylation which was associated with a specific decrease in the translation of ribosomal proteins. In line, the cell size of SNORD42A deletion carrying leukemia cells was decreased. Taken together, these findings establish that high level expression of SNORD42A with concomitant U116 18S rRNA 2´-O-methylation is essential for leukemia cell growth and survival.
Project description:SIRT7 is an NAD+-dependent protein deacetylase with important roles in ribosome biogenesis and cell proliferation. Previous studies have established that SIRT7 is associated with RNA polymerase I, interacts with pre-rRNA and promotes rRNA synthesis. Here we show that SIRT7 is also associated with snoRNAs that are involved in pre-rRNA processing and rRNA maturation. Knockdown of SIRT7 impairs U3 snoRNA-dependent early cleavage steps that are necessary for generation of 18S rRNA. Mechanistically, SIRT7 deacetylates U3-55k, a core component of the U3 snoRNP complex, and reversible acetylation of U3-55k modulates the association of U3-55k with U3 snoRNA. Deacetylation by SIRT7 enhances U3-55k binding to U3 snoRNA, which is a prerequisite for pre-rRNA processing. Under stress conditions, SIRT7 is released from nucleoli, leading to hyperacetylation of U3-55k and attenuation of prerRNA processing. The results reveal a multifaceted role of SIRT7 in ribosome biogenesis, regulating both transcription and processing of rRNA. CLIP-seq was performed in Flag-SIRT7-293T cells.
Project description:Major depressive disorder (MDD) is a severe psychiatric disorder, characterized by deficits in GABAergic and glutamatergic signaling in cortical brain regions. Unpredictable chronic mild stress (UCMS), a murine stress model, induces behavioural and neurobiological changes reminiscent of MDD. Despite increasing knowledge of the cellular complexity of the cortical microcircuitry, our understanding of how distinct cell-types are impacted by UCMS is extremely limited. We thus endeavoured to determine the effect of UCMS on Pyramidal (PYR) cells and three classes of interneurons: Somatostatin (SST), Parvalbumin (PV), and Vasoactive intestinal peptide-expressing (VIP) cells in the medial prefrontal cortex. C57Bl/6 mice, exposed to UCMS or control housing for five weeks, were assessed with a battery of anxiety- and depressive-like behavioural tests. Laser-capture microdissection was used to isolate samples of microcircuit cell-types, which underwent RNA-sequencing. UCMS-exposed mice showed significantly elevated emotionality, and isolate cell-types showed robust specificity. Cell-types exhibited unique transcriptomic profiles after UCMS. Briefly, PYR-cells showed decreased signaling and post-synaptic receptor expression, SST-cells showed increased activation of the unfolded protein response, PV-cells showed increased axonal microtubule expression, and VIP-cells showed increased apoptotic signaling and altered cytoskeletal gene expression. Co-expression analyses revealed that these changes were largely correlated across cell-types and that UCMS increased transcriptome-wide co-expression between PYR and both PV and SST cells. Overall, these findings suggest decreased PYR, SST, and VIP-cell function, elevated PV-cell function, and identify the dysregulation of PYR-cells as a central locus of UCMS-induced transcriptomic change. Further studies interrogating potential antidepressant-like activity of compounds reversing these cell-specific changes are warranted.
Project description:In eukaryotes, ribosomal RNA biogenesis consists of ribosomal DNA transcription to pre-rRNA, which must be modified and processed in the nucleus resulting in the 18S, 5.8S, and 28S ribosomal units. Molecular components involved in this process comprise the catalytic ribonucleoproteins complexes (snoRNPs) formed by non-coding RNAs classified as box C/D and box H/ACA snoRNA that associates to at least four proteins highly conserved through evolution and combined to multiple transient proteins. Taking advantage of computational and multidisciplinary experimental approaches, we determine that the orphan EhARPv2, a member of the Actin-related family from Entamoeba histolytica, interacts with nucleolar proteins. EhARPv2 and its partners here identified colocalize in the nuclear periphery, considered the nucleolus, and interact with both box C/D and H/ACA snoRNAs. Moreover, we find the reassortment of some components of snoRNPs from C/D- or H/ACA complexes mixed in vitro and in entire cells indicating that in E. histolytica snoRNP of C/D or H/ACA machineries alternate using common elements and that EhARPv2 is a part of this peculiar snoRNP. Our findings substantiate a role for EhARPv2 in the biogenesis of ribosomal RNA.
Project description:Osteoarthritis (OA) is a chronic debilitating joint disease which is strongly associated with ageing. OA involves pathological cellular processes in all joint structures and affects articular cartilage integrity, leading to dysfunctional joint articulation. The biomolecular processes that catalyze the disturbances in the articular chondrocyte phenotype leading to OA are poorly understood, and it is expected that a comprehensive understanding of the avenues leading to catabolic changes and disruption of articular chondrocyte homeostasis will provide important cues for future treatments of the condition. Chondrocytes are specialized secretory cells with highly active protein translational machinery, enabling the synthesis and maintenance of the protein-rich cartilage extracellular matrix (ECM). Disturbances in chondrocyte protein translation in cartilage development and OA are connected to mTOR activity, ER stress, unfolded protein response (UPR)and CHOP-mediated apoptosis. These responses change the downstream translational activity of the biosynthesized ribosome. The assembled mammalian ribosome is built from ribosomal RNAs (rRNAs), together with more than 80 different protein subunits. At the heart of the ribosome, the 18S rRNA guides the decoding of the mRNA message, while an ancient ribozyme activity in the 28S rRNA forms the core of the peptidyltransferase center that polymerizes the amino acid sequence encoded by the mRNA into functional proteins. Post-transcriptional maturation of rRNAs is an integral part of the biosynthesis of ribosomes and ribonucleolytic processing of the major 47S rRNA precursor into mature 18S, 5.8S, and 28S rRNAs is rate limiting for ribosome biogenesis. The U3 small nucleolar RNA (snoRNA) is an evolutionarily highly conserved box C/D-class snoRNA which catalyzes the endoribonucleolytic processing of the 5’ external transcribed spacer (ETS) of the 47S pre-rRNA by base complementarity-guided pre-rRNA substrate recognition and plays a crucial role in the maturation of 18S rRNA. Although extensively studied in yeast, it was only recently demonstrated that U3 snoRNA is indispensable for rRNA maturation in human cells. Pathways controlling ribosome activity have previously been described in the regulation of chondrocyte homeostasis. We here now postulate that not only ribosome activity is involved in chondrocyte homeostasis, but that OA pathophysiological situations can also cause alterations in chondrocyte ribosome biogenesis with consequences for cellular protein translation. Since U3 snoRNA-driven rRNA production is rate-limiting in ribosome biogenesis, we hypothesized that the U3 snoRNA is critical for chondrocyte homeostasis. In this study we therefor aimed to determine whether OA pathophysiological conditions interact with chondrocyte U3 snoRNA levels, thereby influencing rRNA levels and chondrocyte translation capacity.
Project description:Background: Small nucleolar RNAs (snoRNAs) are mid-size non-coding RNAs required for ribosomal RNA modification, implying a ubiquitous tissue distribution linked to ribosome synthesis. However, increasing numbers of studies identify extra-ribosomal roles of snoRNAs in modulating gene expression, suggesting more complex snoRNA abundance patterns. Therefore, there is a great need for mapping the snoRNome in different human tissues as the blueprint for snoRNA functions. Results: We used a low structure bias RNA-Seq approach to accurately quantify snoRNAs and compare them to the entire transcriptome in seven healthy human tissues (breast, ovary, prostate, testis, skeletal muscle, liver and brain). We identify 475 expressed snoRNAs categorized in two abundance classes that differ significantly in their function, conservation level and correlation with their host gene: 390 snoRNAs are uniformly expressed and 85 are enriched in the brain or reproductive tissues. Most tissue-enriched snoRNAs are embedded in lncRNAs and display strong correlation of abundance with them, whereas uniformly expressed snoRNAs are mostly embedded in protein-coding host genes and are mainly non- or anticorrelated with them. 59% of the non-correlated or anticorrelated protein-coding host gene/snoRNA pairs feature dual-initiation promoters, compared to only 16% of the correlated non-coding host gene/snoRNA pairs. Conclusions: Our results demonstrate that snoRNAs are not a single homogeneous group of housekeeping genes but include highly regulated tissue-enriched RNAs. Indeed, our work indicates that the architecture of snoRNA host genes varies to uncouple the host and snoRNA expressions in order to meet the different snoRNA abundance levels and functional needs of human tissues.
Project description:SIRT7 is an NAD+-dependent protein deacetylase with important roles in ribosome biogenesis and cell proliferation. Previous studies have established that SIRT7 is associated with RNA polymerase I, interacts with pre-rRNA and promotes rRNA synthesis. Here we show that SIRT7 is also associated with snoRNAs that are involved in pre-rRNA processing and rRNA maturation. Knockdown of SIRT7 impairs U3 snoRNA-dependent early cleavage steps that are necessary for generation of 18S rRNA. Mechanistically, SIRT7 deacetylates U3-55k, a core component of the U3 snoRNP complex, and reversible acetylation of U3-55k modulates the association of U3-55k with U3 snoRNA. Deacetylation by SIRT7 enhances U3-55k binding to U3 snoRNA, which is a prerequisite for pre-rRNA processing. Under stress conditions, SIRT7 is released from nucleoli, leading to hyperacetylation of U3-55k and attenuation of prerRNA processing. The results reveal a multifaceted role of SIRT7 in ribosome biogenesis, regulating both transcription and processing of rRNA.
Project description:We evaluated the profile of miRNA and snoRNA expression in 7 solitary CRC and matched normal colorectal tissues using the Affymetrix GeneChip miRNA 1.0 array. We found that global dysregulated miRNAs and snoRNAs between cancer tissue and normal mucosa in solitary CRC. Our findings firstly implicates that dysregulation of snoRNAs and miRNA may play important role in the cancinogenesis and present therapeutic targets for solitary CRC. Examination of microRNA and snoRNA expression in cancer and matched normal tissues of solitary CRC
Project description:Small nucleolar RNAs (snoRNA) are non-coding RNAs known for guiding RNA modifications including 2ʹ-O-methylation (Nm) and pseudouridine (Ψ). While snoRNAs may also interact with other RNAs such as mRNA, the full repertoire of RNAs targeted by snoRNA remains elusive due to the lack of effective technologies that identify snoRNA targets transcriptome-wide. Here we develop a chemical crosslinking-based approach that comprehensively detects cellular RNA targets of snoRNAs, yielding thousands of previously unrecognized snoRNA-mRNA interactions in human cells and mouse brain tissues. Many interactions occur outside of snoRNA-guided rRNA modification sites, hinting at non-canonical functions beyond RNA modification. We find that one of these snoRNAs, SNORA73, targets mRNAs that encode secretory proteins and membrane proteins. SNORA73 also interacts with 7SL RNA, part of the signal recognition particle (SRP) required for protein secretion. The mRNA-SNORA73-7SL RNA interactions enhance the association of the SNORA73-target mRNAs with SRP, thereby facilitating secretion of the encoded proteins.