Identification and dynamic changes of RNAs isolated from RALY-containing ribonucleoprotein complexes

Proteomic Mendelian randomization to identify protein biomarkers of telomere length

Shortening of telomere length (TL) is correlated with many age-related disorders and is a hallmark of biological aging. This study used proteome-wide Mendelian randomization to identify the protein biomarkers associated with telomere length. Protein quantitative trait loci (pQTL) were derived from two studies, the deCODE Health study (4907 plasma proteins) and the UK Biobank Pharma Proteomics Project (2923 plasma proteins). Summary data from genome-wide association studies (GWAS) for TL were obtained from the UK Biobank (472,174 cases) and GWAS Catalog (418,401 cases). The association between proteins and TL was further assessed using colocalization and summary data-based Mendelian randomization (SMR) analyses. The protein-protein network, druggability assessment, and phenome-wide MR were used to further evaluate the potential biological effects, druggability, and safety of the target proteins. Proteome-wide MR analysis identified 22 plasma proteins that were causally associated with telomere length. Five of these proteins (APOE, SPRED2, MAX, RALY, and PSMB1) had the highest evidence of association with TL and should be prioritized. This study revealed telomere length-related protein biomarkers, providing new insights into the development of new treatment targets for chronic diseases and anti-aging intervention strategies.

O-GlcNAcylated RALY Contributes to Hepatocellular Carcinoma Cells Proliferation by Regulating USP22 mRNA Nuclear Export

Hepatocellular carcinoma (HCC) is one of the most prevalent and deadly tumors; however, its pathogenic mechanism remains largely elusive. In-depth researches are needed to reveal the expression regulatory mechanisms and functions of the RNA-binding protein RALY in HCC. Here, we identify RALY as a highly expressed oncogenic factor that affects HCC cells proliferation both in vitro and in vivo. O-GlcNAcylation of RALY at Ser176 enhances its stability by protecting RALY from TRIM27-mediated ubiquitination, thus maintaining hyper-expression of the RALY protein. Mechanistically, RALY interacts with USP22 messenger RNA, as revealed by RNA immunoprecipitation, to increase their cytoplasmic localization and protein expression, thereby promoting the proliferation of HCC cells. Furthermore, we develop a novel RALY protein degrader based on peptide proteolysis-targeting chimeras, named RALY-PROTAC, which we chemically synthesize by linking a RALY-targeting peptide with the E3 ubiquitin ligase recruitment ligand pomalidomide. In conclusion, our findings demonstrate a novel mechanism by which O-GlcNAcylation/RALY/USP22 mRNA axis aggravates HCC cells proliferation. RALY-PROTACs as degraders of the RALY protein exhibit potential as therapeutic drugs for RALY-overexpressing HCC.

MEF2D facilitates liver metastasis of gastric cancer cells through directly inducing H1X under IL-13 stimulation

Liver metastasis is the most common metastatic occurrence in gastric cancer patients, although the precise mechanism behind it remains unclear. Through a combination of proteomics and quantitative RT-PCR, our study has revealed a significant correlation between the upregulation of myocyte enhancer factor-2D (MEF2D) and both distant metastasis and poor prognosis in gastric cancer patients. In mouse models, we observed that overexpressing or knocking down MEF2D in gastric cancer cells respectively promoted or inhibited liver metastasis. Furthermore, our research has demonstrated that MEF2D regulates the transcriptional activation of H1X by binding to the H1X promoter. This regulation leads to the upregulation of H1X, which, in turn, promotes the in vivo metastasis of gastric cancer cells along with the upregulation of the downstream gene β-CATENIN. Additionally, we found that the expression of MEF2D and H1X at both mRNA and protein levels can be induced by the inflammatory factor IL-13, and this induction exhibits a time gradient dependence. In human gastric cancer tissues, the expression of IL13RA1, the receptor for IL-13, positively correlates with the expression of MEF2D and H1X. IL13RA1 has been identified as an intermediate receptor through which IL-13 regulates MEF2D. In conclusion, our findings suggest that MEF2D plays a crucial role in promoting liver metastasis of gastric cancer by upregulating H1X and downstream target β-CATENIN in response to IL-13 stimulation. Targeting MEF2D could therefore be a promising therapeutic strategy for the clinical management of gastric cancer. STATEMENT OF SIGNIFICANCE: MEF2D promotes its transcriptional activation in gastric cancer cells by binding to the H1X promoter and is upregulated by IL-13-IL13RA1, thereby promoting distant metastasis of gastric cancer.

Autophagy mediated degradation of MITA/TBK1/IRF3 by a hnRNP family member attenuates interferon production in fish

HnRNP A/B belongs to the heterogeneous nuclear ribonucleoprotein (hnRNP) family and plays an important role in regulating viral protein translation and genome replication. Here, we found that overexpression of hnRNP A/B promoted spring viremia of carp virus (SVCV) and cyprinid herpesvirus 3 (CyHV3) replication. Further, hnRNP A/B was shown to act as a negative regulator of type I interferon (IFN) response. Mechanistically, hnRNP A/B interacted with MITA, TBK1 and IRF3 to initiate their degradation. In addition, hnRNP A/B bound to the kinase domain of TBK1, the C terminal domain of MITA and IAD domain of IRF3, and the RRM1 domain of hnRNP A/B bound to TBK1, RRM2 domain bound to IRF3 and MITA. Our study provides novel insights into the functions of hnRNP A/B in regulating host antiviral response.

Nuclear ribonucleoprotein RALY downregulates foot-and-mouth disease virus replication but antagonized by viral 3C protease

The internal ribosome entry site (IRES) element constitutes a cis-acting RNA regulatory sequence that recruits the ribosomal initiation complex in a cap-independent manner, assisted by various RNA-binding proteins and IRES trans-acting factors. Foot-and-mouth disease virus (FMDV) contains a functional IRES element and takes advantage of this element to subvert host translation machinery. Our study identified a novel mechanism wherein RALY, a member of the heterogeneous nuclear ribonucleoproteins (hnRNP) family belonging to RNA-binding proteins, binds to the domain 3 of FMDV IRES via its RNA recognition motif residue. This interaction results in the downregulation of FMDV replication by inhibiting IRES-driven translation. Furthermore, our findings reveal that the inhibitory effect exerted by RALY on FMDV replication is not attributed to the FMDV IRES-mediated assembly of translation initiation complexes but rather to the impediment of 80S ribosome complex formation after binding with 40S ribosomes. Conversely, 3Cpro of FMDV counteracts RALY-mediated inhibition by the ubiquitin-proteasome pathway. Therefore, these results indicate that RALY, as a novel critical IRES-binding protein, inhibits FMDV replication by blocking the formation of 80S ribosome, providing a deeper understanding of how viruses recruit and manipulate host factors.

IMPORTANCE

The translation of FMDV genomic RNA driven by IRES element is a crucial step for virus infections. Many host proteins are hijacked to regulate FMDV IRES-dependent translation, but the regulatory mechanism remains unknown. Here, we report for the first time that cellular RALY specifically interacts with the IRES of FMDV and negatively regulates viral replication by blocking 80S ribosome assembly on FMDV IRES. Conversely, RALY-mediated inhibition is antagonized by the viral 3C protease by the ubiquitin-proteasome pathway. These results would facilitate further understanding of virus-host interactions and translational control during viral infection.

RALY participates in nerve trauma-induced nociceptive hypersensitivity through triggering Eif4g2 gene expression in primary sensory neurons

BACKGROUND AND PURPOSE

Peripheral nerve trauma-induced dysregulation of pain-associated genes in the primary sensory neurons of dorsal root ganglion (DRG) contributes to neuropathic pain genesis. RNA-binding proteins participate in gene transcription. We hypothesized that RALY, an RNA-binding protein, participated in nerve trauma-induced dysregulation of DRG pain-associated genes and nociceptive hypersensitivity.

METHODS AND RESULTS

Immunohistochemistry staining showed that RALY was expressed exclusively in the nuclei of DRG neurons. Peripheral nerve trauma caused by chronic constriction injury (CCI) of unilateral sciatic nerve produced time-dependent increases in the levels of Raly mRNA and RALY protein in injured DRG. Blocking this increase through DRG microinjection of adeno-associated virus 5 (AAV5)-expressing Raly shRNA reduced the CCI-induced elevation in the amount of eukaryotic initiation factor 4 gamma 2 (Eif4g2) mRNA and Eif4g2 protein in injured DRG and mitigated the development and maintenance of CCI-induced nociceptive hypersensitivity, without altering basal (acute) response to noxious stimuli and locomotor activity. Mimicking DRG increased RALY through DRG microinjection of AAV5 expressing Raly mRNA up-regulated the expression of Eif4g2 mRNA and Eif4g2 protein in the DRG and led to hypersensitive responses to noxious stimuli in the absence of nerve trauma. Mechanistically, CCI promoted the binding of RALY to the promoter of Eif4g2 gene and triggered its transcriptional activity.

CONCLUSION AND IMPLICATIONS

Our findings indicate that RALY participates in nerve trauma-induced nociceptive hypersensitivity likely through transcriptionally triggering Eif4g2 expression in the DRG. RALY may be a potential target in neuropathic pain management.

Research Advances on Swine Acute Diarrhea Syndrome Coronavirus

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a virulent pathogen that causes acute diarrhea in piglets. The virus was first discovered in Guangdong Province, China, in 2017 and has since emerged in Jiangxi, Fujian, and Guangxi Provinces. The outbreak exhibited a localized and sporadic pattern, with no discernable temporal continuity. The virus can infect human progenitor cells and demonstrates considerable potential for cross-species transmission, representing a potential risk for zoonotic transmission. Therefore, continuous surveillance of and comprehensive research on SADS-CoV are imperative. This review provides an overview of the temporal and evolutionary features of SADS-CoV outbreaks, focusing on the structural characteristics of the virus, which serve as the basis for discussing its potential for interspecies transmission. Additionally, the review summarizes virus-host interactions, including the effects on host cells, as well as apoptotic and autophagic behaviors, and discusses prevention and treatment modalities for this viral infection.

SUMOylation of RALY promotes vasculogenic mimicry in glioma cells via the FOXD1/DKK1 pathway

Human malignant gliomas are the most common and aggressive primary malignant tumors of the human central nervous system. Vasculogenic mimicry (VM), which refers to the formation of a tumor blood supply system independently of endothelial cells, contributes to the malignant progression of glioma. Therefore, VM is considered a potential target for glioma therapy. Accumulated evidence indicates that alterations in SUMOylation, a reversible post-translational modification, are involved in tumorigenesis and progression. In the present study, we found that UBA2 and RALY were upregulated in glioma tissues and cell lines. Downregulation of UBA2 and RALY inhibited the migration, invasion, and VM of glioma cells. RALY can be SUMOylated by conjugation with SUMO1, which is facilitated by the overexpression of UBA2. The SUMOylation of RALY increases its stability, which in turn increases its expression as well as its promoting effect on FOXD1 mRNA. The overexpression of FOXD1 promotes DKK1 transcription by activating its promoter, thereby promoting glioma cell migration, invasion, and VM. Remarkably, the combined knockdown of UBA2, RALY, and FOXD1 resulted in the smallest tumor volumes and the longest survivals of nude mice in vivo. UBA2/RALY/FOXD1/DKK1 axis may play crucial roles in regulating VM in glioma, which may contribute to the development of potential strategies for the treatment of gliomas.

TERRA stability is regulated by RALY and polyadenylation in a telomere-specific manner

Telomeric repeat-containing RNA (TERRA) is a long non-coding RNA transcribed from telomeres that plays key roles in telomere maintenance. A fraction of TERRA is polyadenylated, and the presence of the poly(A) tail influences TERRA localization and stability. However, the mechanisms of TERRA biogenesis remain mostly elusive. Here, we show that the stability of TERRA transcripts is regulated by the RNA-binding protein associated with lethal yellow mutation (RALY). RALY depletion results in lower TERRA levels, impaired localization of TERRA at telomeres, and ultimately telomere damage. Importantly, we show that TERRA polyadenylation is telomere specific and that RALY preferentially stabilizes non-polyadenylated TERRA transcripts. Finally, we report that TERRA interacts with the poly(A)-binding protein nuclear 1 (PABPN1). Altogether, our results indicate that TERRA stability is regulated by the interplay between RALY and PABPN1, defined by the TERRA polyadenylation state. Our findings also suggest that different telomeres may trigger distinct TERRA-mediated responses.

Multiple functions of heterogeneous nuclear ribonucleoproteins in the positive single-stranded RNA virus life cycle

The heterogeneous nuclear ribonucleoproteins (hnRNPs) are a diverse family of RNA binding proteins that are implicated in RNA metabolism, such as alternative splicing, mRNA stabilization and translational regulation. According to their different cellular localization, hnRNPs display multiple functions. Most hnRNPs were predominantly located in the nucleus, but some of them could redistribute to the cytoplasm during virus infection. HnRNPs consist of different domains and motifs that enable these proteins to recognize predetermined nucleotide sequences. In the virus-host interactions, hnRNPs specifically bind to viral RNA or proteins. And some of the viral protein-hnRNP interactions require the viral RNA or other host factors as the intermediate. Through various mechanisms, hnRNPs could regulate viral translation, viral genome replication, the switch of translation to replication and virion release. This review highlights the common features and the distinguish roles of hnRNPs in the life cycle of positive single-stranded RNA viruses.

Analysis of Interaction Network Between Host Protein and M Protein of Swine Acute Diarrhea Syndrome Coronavirus

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is an enterovirus that can cause acute diarrhea and death in piglets and cause serious economic losses to the pig industry. SADS-CoV membrane (M) protein mainly plays a key role in biological processes, such as virus assembly, budding, and host innate immune regulation. Understanding the interaction between M protein and host proteins is very important to define the molecular mechanism of cells at the protein level and to understand specific cellular physiological pathways. In this study, 289 host proteins interacting with M protein were identified by glutathione-S-transferase (GST) pull-down combined with liquid chromatography-mass spectrometry (LC-MS/MS), and the protein-protein interaction (PPI) network was established by Gene Ontology (GO) terms and Kyoto Encyclopedia of Gene and Genomes (KEGG) pathways analysis. Results showed that SADS-CoV M protein was mainly associated with the host metabolism, signal transduction, and innate immunity. The Co-Immunoprecipitation (CO-IP) validation results of six randomly selected proteins, namely, Rab11b, voltage-dependent anion-selective channel 1 (VDAC1), Ribosomal Protein L18 (RPL18), RALY, Ras Homolog Family Member A (RHOA), and Annexin A2 (ANXA2), were consistent with LC-MS results. In addition, overexpression of RPL18 and PHOA significantly promoted SADS-CoV replication, while overexpression of RALY antagonized viral replication. This work will help to clarify the function of SADS-CoV M protein in the life cycle of SADS-CoV.

RALY regulate the proliferation and expression of immune/inflammatory response genes via alternative splicing of FOS

RALY is a multifunctional RNA-binding protein involved in cancer metastasis, prognosis, and chemotherapy resistance in various cancers. However, the molecular mechanism of which is still unclear. We have established RALY overexpression cell lines and studied the effect of RALY on proliferation and apoptosis in HeLa cells. Then we used RNA-seq to analyze the transcriptomes data. Lastly, RT-qPCR experiments had performed to confirm the RNA-seq results. We found that the overexpression of RALY in HeLa cells inhibited proliferation. Moreover, the overexpression of RALY changed the gene expression profile, and the significant upregulation of genes involved immune/inflammatory response related biological process by NOD-like receptor signaling pathway cytokine-cytokine receptor interaction. The significant downregulation genes involved innate immune response by the Primary immunodeficiency pathway. Notably, IFIT1, IFIT2, IFTI3, IFI44, HERC4, and OASL expression had inhibited by the overexpression of RALY. Furthermore, RALY negatively regulates the expression of transcription factors FOS and FOSB. Notably, we found that 645 alternative splicing events had regulated by overexpression of RALY, which is highly enriched in transcription regulation, RNA splicing, and cell proliferation biological process by the metabolic pathway. We show that RALY regulates the expression of immune/inflammatory response-related genes via alternative splicing of FOS in HeLa cells. The novel role of RALY in regulating immune/inflammatory gene expression may explain its function in regulating chemotherapy resistance and provides novel insights into further exploring the molecular mechanism of RALY in regulating cancer immunity and chemo/immune therapies.

Studying RNP Composition with RIP

RNA is never left alone throughout its life cycle. Together with proteins, RNAs form membraneless organelles, called ribonucleoprotein particles (RNPs) where these two types of macromolecules strongly influence each other's functions and destinies. RNA immunoprecipitation is still one of the favorite techniques which allows to simultaneously study both the RNA and protein composition of the RNP complex.

DHX30 Coordinates Cytoplasmic Translation and Mitochondrial Function Contributing to Cancer Cell Survival

DHX30 was recently implicated in the translation control of mRNAs involved in p53-dependent apoptosis. Here, we show that DHX30 exhibits a more general function by integrating the activities of its cytoplasmic isoform and of the more abundant mitochondrial one. The depletion of both DHX30 isoforms in HCT116 cells leads to constitutive changes in polysome-associated mRNAs, enhancing the translation of mRNAs coding for cytoplasmic ribosomal proteins while reducing the translational efficiency of the nuclear-encoded mitoribosome mRNAs. Furthermore, the depletion of both DHX30 isoforms leads to higher global translation but slower proliferation and lower mitochondrial energy metabolism. Isoform-specific silencing supports a role for cytoplasmic DHX30 in modulating global translation. The impact on translation and proliferation was confirmed in U2OS and MCF7 cells. Exploiting RIP, eCLIP, and gene expression data, we identified fourteen mitoribosome transcripts we propose as direct DHX30 targets that can be used to explore the prognostic value of this mechanism in cancer. We propose that DHX30 contributes to cell homeostasis by coordinating ribosome biogenesis, global translation, and mitochondrial metabolism. Targeting DHX30 could, thus, expose a vulnerability in cancer cells.

Adenovirus-mediated ubiquitination alters protein-RNA binding and aids viral RNA processing

Viruses promote infection by hijacking the ubiquitin machinery of the host to counteract or redirect cellular processes. Adenovirus encodes two early proteins, E1B55K and E4orf6, that together co-opt a cellular ubiquitin ligase complex to overcome host defences and promote virus production. Adenovirus mutants lacking E1B55K or E4orf6 display defects in viral RNA processing and protein production, but previously identified substrates of the redirected ligase do not explain these phenotypes. Here, we used a quantitative proteomics approach to identify substrates of E1B55K/E4orf6-mediated ubiquitination that facilitate RNA processing. While all currently known cellular substrates of E1B55K and E4orf6 are degraded by the proteasome, we uncovered RNA-binding proteins as high-confidence substrates that are not decreased in overall abundance. We focused on two RNA-binding proteins, RALY and hnRNP-C, which we confirm are ubiquitinated without degradation. Knockdown of RALY and hnRNP-C increased levels of viral RNA splicing, protein abundance and progeny production during infection with E1B55K-deleted virus. Furthermore, infection with E1B55K-deleted virus resulted in an increased interaction of hnRNP-C with viral RNA and attenuation of viral RNA processing. These data suggest that viral-mediated ubiquitination of RALY and hnRNP-C relieves a restriction on viral RNA processing and reveal an unexpected role for non-degradative ubiquitination in the manipulation of cellular processes during virus infection.

Regulation of cellular sterol homeostasis by the oxygen responsive noncoding RNA lincNORS

We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG locus, entirely distinct from the previously described miR-193b-365a tandem. While inducible by low O₂ in a variety of cells and associated with hypoxia in vivo, our studies show that lincNORS is subject to multiple regulatory inputs, including estrogen signals. Biochemically, this lincRNA fine-tunes cellular sterol/steroid biosynthesis by repressing the expression of multiple pathway components. Mechanistically, the function of lincNORS requires the presence of RALY, an RNA-binding protein recently found to be implicated in cholesterol homeostasis. We also noticed the proximity between this locus and naturally occurring genetic variations highly significant for sterol/steroid-related phenotypes, in particular the age of sexual maturation. An integrative analysis of these variants provided a more formal link between these phenotypes and lincNORS, further strengthening the case for its biological relevance.

Alternative Splicing in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) accounts for the majority of primary liver cancer cases, with more than 850,000 new diagnoses per year globally. Recent trends in the United States have shown that liver cancer mortality has continued to increase in both men and women, while 5-year survival remains below 20%. Understanding key mechanisms that drive chronic liver disease progression to HCC can reveal new therapeutic targets and biomarkers for early detection of HCC. In that regard, many studies have underscored the importance of alternative splicing as a source of novel HCC prognostic markers and disease targets. Alternative splicing of pre-mRNA provides functional diversity to the genome, and endows cells with the ability to rapidly remodel the proteome. Genes that control fundamental processes, such as metabolism, cell proliferation, and apoptosis, are altered globally in HCC by alternative splicing. This review highlights the major splicing factors, RNA binding proteins, transcriptional targets, and signaling pathways that are of key relevance to HCC. We highlight primary research from the past 3-5 years involving functional interrogation of alternative splicing in rodent and human liver, using both large-scale transcriptomic and focused mechanistic approaches. Because this is a rapidly advancing field, we anticipate that it will be transformative for the future of basic liver biology, as well as HCC diagnosis and management.

RALY may cause an aggressive biological behavior and a dismal prognosis in non-small-cell lung cancer

RALY is a member of the heterogeneous nuclear ribonucleoprotein (hnRNP), an RNA-binding protein that plays a role in mRNA splicing and metabolism, may be involved in tumorigenesis and development. Some studies have shown that RALY plays a role in promoting cancer in a variety of tumors. However, the biological function and molecular mechanism of RALY in non-small cell lung cancer (NSCLC) remain unknown. TCGA databases were used to gather RALY expression data in NSCLC, the results indicate that RALY is highly expressed in cancer tissue of NSCLC patients. Then we demonstrated that RALY gene expression was notably upregulated in NSCLC tissue and cell lines (A549 and SK-MES-1), and was associated with lymph node metastasis (P = 0.007) and poorer overall survival in NSCLC patients. Subsequently, RALY in A549 and SK-MES-1 cells was knocked down by lentivirus to analyze the consequences of RALY on the biological behavior of NSCLC cell lines. Our results indicated that RALY knockdown impaired NSCLC cells proliferation, migration, and invasion, as well as arrested cells in G1 phase, and the reintroduction of RALY recused its biological phenotype. Furthermore, RALY knockdown down-regulated the expression levels of c-Myc, Cyclin D1, CDK4, MMP9, Rho A ,Rho C, N-cadherin and β-catenin, and up-regulated the expression levels of P27, Rho B and E-cadherin. Therefore, targeting RALY could be a promising molecular target for NSCLC treatment.

A Combined Multi-Cohort Approach Reveals Novel and Known Genome-Wide Selection Signatures for Wool Traits in Merino and Merino-Derived Sheep Breeds

Merino sheep represents a valuable genetic resource worldwide. In this study, we investigated selection signatures in Merino (and Merino-derived) sheep breeds using genome-wide SNP data and two different approaches: a classical FST-outlier method and an approach based on the analysis of local ancestry in admixed populations. In order to capture the most reliable signals, we adopted a combined, multi-cohort approach. In particular, scenarios involving four Merino breeds (Spanish Merino, Australian Merino, Chinese Merino, and Sopravissana) were tested via the local ancestry approach, while nine pair-wise breed comparisons contrasting the above breeds, as well as the Gentile di Puglia breed, with non-Merino breeds from the same geographic area were tested via the FST-outlier method. Signals observed using both methods were compared with genome-wide patterns of distribution of runs of homozygosity (ROH) islands. Novel and known selection signatures were detected. The most reliable signals were observed on OAR 3 (MSRB3 and LEMD3), OAR10 (FRY and RXFP2), OAR 13 (RALY), OAR17 (FAM101A), and OAR18 (NFKBIA, SEC23A, and PAX9). All the above overlapped with known QTLs for wool traits, and evidences from the literature of their involvement in skin/hair/wool biology, as well as gene network analysis, further corroborated these results. The signal on OAR10 also contains well known evidence for association with horn morphology and polledness. More elusive biological evidences of association with the Merino phenotype were observed for a number of other genes, notably LOC101120019 and TMEM132B (OAR17), LOC105609948 (OAR3), LOC101110773 (OAR10), and EIF2S2 (OAR17). Taken together, the above results further contribute to decipher the genetic basis underlying the Merino phenotype.

Long noncoding RNA EMS connects c-Myc to cell cycle control and tumorigenesis

Deregulated expression of c-Myc is an important molecular hallmark of cancer. The oncogenic function of c-Myc has been largely attributed to its intrinsic nature as a master transcription factor. Here, we report the long noncoding RNA (lncRNA) E2F1 messenger RNA (mRNA) stabilizing factor (EMS) as a direct c-Myc transcriptional target. EMS functions as an oncogenic molecule by promoting G1/S cell cycle progression. Mechanistically, EMS cooperates with the RNA binding protein RALY to stabilize E2F1 mRNA, and thereby increases E2F1 expression. Furthermore, EMS is able to connect c-Myc to cell cycle control and tumorigenesis via modulating E2F1 mRNA stability. Together, these findings reveal a previously unappreciated mechanism through which c-Myc induces E2F1 expression and also implicate EMS as an important player in the regulation of c-Myc function.

Mapping the Ku Interactome Using Proximity-Dependent Biotin Identification in Human Cells

The Ku heterodimer, composed of Ku70 and Ku80, is best characterized for its role in repairing double-stranded DNA breaks but is also known to participate in other regulatory processes. Despite our understanding of Ku protein interplay during DNA repair, the extent of Ku's protein interactions in other processes has never been fully determined. Using proximity-dependent biotin identification (BioID) and affinity purification coupled to mass spectrometry (AP-MS) with wild-type Ku70, we identified candidate proteins that interact with the Ku heterodimer in HEK293 cells, in the absence of exogenously induced DNA damage. BioID analysis identified approximately 250 nuclear proteins, appearing in at least two replicates, including known Ku-interacting factors such as MRE11A, WRN, and NCOA6. Meanwhile, AP-MS analysis identified approximately 50 candidate proteins. Of the novel protein interactors identified, many were involved in functions already suspected to involve Ku such as transcriptional regulation, DNA replication, and DNA repair, while several others suggest that Ku may be involved in additional functions such as RNA metabolism, chromatin-remodeling, and microtubule dynamics. Using a combination of BioID and AP-MS, this is the first report that comprehensively characterizes the Ku protein interaction landscape, revealing new cellular processes and protein complexes involving the Ku complex.

Overexpression of RALY promotes migration and predicts poor prognosis in hepatocellular carcinoma

Introduction

RALY plays a critical role in promoting invasiveness and is associated with poor prognosis in different types of cancers. However, the prognostic value of RALY and its precise role in hepatocellular carcinoma (HCC) remain unknown.

Materials and methods

We detected the expression of RALY in 127 clinical HCC tissue samples and seven HCC cell lines by immunohistochemical staining and Western blotting. The prognostic value of RALY expression was assessed using the Kaplan–Meier method. The expression and prognostic value of RALY were also studied by bioinformatics analysis of data from the Gene Expression Omnibus and The Cancer Genome Atlas. The biological influence of RALY on HCC cell lines was studied using proliferation, transwell migration, and invasion assays in vitro.

Results

The expression of RALY in HCC tissues was significantly higher than that in adjacent normal liver tissues. Abnormally high expression of RALY was associated with tumor size (P=0.031), TNM stage (P=0.026), presurgical serum AFP levels (P=0.025), and vascular invasion (P=0.001). Kaplan–Meier analysis demonstrated that higher expression of RALY correlated with poorer overall survival and disease-free survival in HCC patients. High RALY expression was an independent adverse prognostic factor for overall survival (HR =2.559, 95% CI: 1.710–3.827, P<0.001) and disease-free survival (HR =2.053, 95% CI: 1.384–3.047, P<0.001) in HCC. Moreover, knockdown of RALY expression using a specific shRNA suppressed the proliferation, migration, and invasion capabilities of HCC cells in vitro. Knockdown of RALY expression in HCC cell lines resulted in upregulation of E-cadherin and downregulation of N-cadherin, vimentin, and snail.

Conclusion

Taken together, our results indicate that RALY represents a biomarker for the prognosis of patients with HCC and highlight the importance of RALY as an oncogene in HCC.

The hnRNP RALY regulates PRMT1 expression and interacts with the ALS-linked protein FUS: implication for reciprocal cellular localization

The RBP associated with lethal yellow mutation (RALY) is a member of the heterogeneous nuclear ribonucleoprotein family whose transcriptome and interactome have been recently characterized. RALY binds poly-U rich elements within several RNAs and regulates the expression as well as the stability of specific transcripts. Here we show that RALY binds PRMT1 mRNA and regulates its expression. PRMT1 catalyzes the arginine methylation of Fused in Sarcoma (FUS), an RNA-binding protein that interacts with RALY. We demonstrate that RALY down-regulation decreases protein arginine N-methyltransferase 1 levels, thus reducing FUS methylation. It is known that mutations in the FUS nuclear localization signal (NLS) retain the protein to the cytosol, promote aggregate formation, and are associated with amyotrophic lateral sclerosis. Confirming that inhibiting FUS methylation increases its nuclear import, we report that RALY knockout enhances FUS NLS mutants’ nuclear translocation, hence decreasing aggregate formation. Furthermore, we characterize the RNA-dependent interaction of RALY with FUS in motor neurons. We show that mutations in FUS NLS as well as in RALY NLS reciprocally alter their localization and interaction with target mRNAs. These data indicate that RALY’s activity is impaired in FUS pathology models, raising the possibility that RALY might modulate disease onset and/or progression.

The hnRNP RALY regulates transcription and cell proliferation by modulating the expression of specific factors including the proliferation marker E2F1

The heterogeneous nuclear ribonucleoproteins (hnRNP) form a large family of RNA-binding proteins that exert numerous functions in RNA metabolism. RALY is a member of the hnRNP family that binds poly-U-rich elements within several RNAs and regulates the expression of specific transcripts. RALY is up-regulated in different types of cancer, and its down-regulation impairs cell cycle progression. However, the RALY's role in regulating RNA levels remains elusive. Here, we show that numerous genes coding for factors involved in transcription and cell cycle regulation exhibit an altered expression in RALY-down-regulated HeLa cells, consequently causing impairments in transcription, cell proliferation, and cell cycle progression. Interestingly, by comparing the list of RALY targets with the list of genes affected by RALY down-regulation, we found an enrichment of RALY mRNA targets in the down-regulated genes upon RALY silencing. The affected genes include the E2F transcription factor family. Given its role as proliferation-promoting transcription factor, we focused on E2F1. We demonstrate that E2F1 mRNA stability and E2F1 protein levels are reduced in cells lacking RALY expression. Finally, we also show that RALY interacts with transcriptionally active chromatin in both an RNA-dependent and -independent manner and that this association is abolished in the absence of active transcription. Taken together, our results highlight the importance of RALY as an indirect regulator of transcription and cell cycle progression through the regulation of specific mRNA targets, thus strengthening the possibility of a direct gene expression regulation exerted by RALY.

RNA binding protein RALY promotes Protein Arginine Methyltransferase 1 alternatively spliced isoform v2 relative expression and metastatic potential in breast cancer cells

Aberrant expression of Protein Arginine Methyltransferases (PRMTs) has been observed in several cancer types, including breast cancer. We previously reported that the PRMT1v2 isoform, which is generated through inclusion of alternative exon 2, is overexpressed in breast cancer cells and promotes their invasiveness. However, the precise mechanism by which expression of this isoform is controlled and how it is dysregulated in breast cancer remains unknown. Using a custom RNA interference-based screen, we identified several RNA binding proteins (RBP) which, when knocked down, altered the relative abundance of the alternatively spliced PRMT1v2 isoform. Amongst the top hits were SNW Domain containing 1 (SNW1) and RBP-associated with lethal yellow mutation (RALY), which both associated with the PRMT1 pre-mRNA and upon depletion caused an increase or decrease in the relative abundance of PRMT1v2 isoform mRNA and protein. Most importantly, a significant decrease in invasion was observed upon RALY knockdown in aggressive breast cancer cells, consistent with targeting PRMT1v2 directly, and this effect was rescued by the exogenous re-expression of PRMT1v2. We show that SNW1 expression is decreased, while RALY expression is increased in breast cancer cells and tumours, which correlates with decreased patient survival. This work revealed crucial insight into the mechanisms regulating the expression of the PRMT1 alternatively spliced isoform v2 and its dysregulation in breast cancer. It also provides proof-of-concept support for the development of therapeutic strategies where regulators of PRMT1 exon 2 alternative splicing are targeted as an approach to selectively reduce PRMT1v2 levels and metastasis in breast cancer.