Depletion of UBA protein 2-like protein inhibits growth and induces apoptosis of human colorectal carcinoma cells

UBAP2L ensures homeostasis of nuclear pore complexes at the intact nuclear envelope

Assembly of macromolecular complexes at correct cellular sites is crucial for cell function. Nuclear pore complexes (NPCs) are large cylindrical assemblies with eightfold rotational symmetry, built through hierarchical binding of nucleoporins (Nups) forming distinct subcomplexes. Here, we uncover a role of ubiquitin-associated protein 2-like (UBAP2L) in the assembly and stability of properly organized and functional NPCs at the intact nuclear envelope (NE) in human cells. UBAP2L localizes to the nuclear pores and facilitates the formation of the Y-complex, an essential scaffold component of the NPC, and its localization to the NE. UBAP2L promotes the interaction of the Y-complex with POM121 and Nup153, the critical upstream factors in a well-defined sequential order of Nups assembly onto NE during interphase. Timely localization of the cytoplasmic Nup transport factor fragile X-related protein 1 (FXR1) to the NE and its interaction with the Y-complex are likewise dependent on UBAP2L. Thus, this NPC biogenesis mechanism integrates the cytoplasmic and the nuclear NPC assembly signals and ensures efficient nuclear transport, adaptation to nutrient stress, and cellular proliferative capacity, highlighting the importance of NPC homeostasis at the intact NE.

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.

Ubiquitin Binding Protein 2-Like (UBAP2L): is it so NICE After All?

Ubiquitin Binding Protein 2-like (UBAP2L, also known as NICE-4) is a ubiquitin- and RNA-binding protein, highly conserved in metazoans. Despite its abundance, its functions have only recently started to be characterized. Several studies have demonstrated the crucial involvement of UBAP2L in various cellular processes such as cell cycle regulation, stem cell activity and stress-response signaling. In addition, UBAP2L has recently emerged as a master regulator of growth and proliferation in several human cancers, where it is suggested to display oncogenic properties. Given that this versatile protein is involved in the regulation of multiple and distinct cellular pathways, actively contributing to the maintenance of cell homeostasis and survival, UBAP2L might represent a good candidate for future therapeutic studies. In this review, we discuss the current knowledge and latest advances on elucidating UBAP2L cellular functions, with an aim to highlight the importance of targeting UBAP2L for future therapies.

UBAP2L promotes gastric cancer metastasis by activating NF-κB through PI3K/AKT pathway

Ubiquitin-associated protein 2-like (UBAP2L) is highly expressed in various types of tumors and has been shown to participate in tumor growth and metastasis; however, its role in gastric cancer (GC) remains unknown. In this study, we observed that UBAP2L expression was markedly elevated in GC tissues and five GC cell lines. Higher expression of UBAP2L was associated with poor prognosis as revealed by bioinformatics analysis on online websites and laboratory experiments. Knockdown of UBAP2L impeded the migration and invasion abilities of GC cell lines. In contrast, its overexpression enhanced the migration and invasion abilities of GC cell lines. Overexpression of UBAP2L also increased the number and size of lung metastatic nodules in vivo. According to the results of mass spectrometry and pathway annotation of the identified proteins, the PI3K/AKT pathway was found to be related to UBAP2L regulation. Further exploration and rescue experiments revealed that UBAP2L stimulates the expression and nuclear aggregation of p65 and promotes the expression of SP1 by activating the PI3K/AKT pathway. In summary, our findings indicate that UBAP2L regulates GC metastasis through the PI3K/AKT/SP1/NF-κB axis. Thus, targeting UBAP2L may be a potential therapeutic strategy for GC.

PQN-59 antagonizes microRNA-mediated repression during post-embryonic temporal patterning and modulates translation and stress granule formation in C. elegans

microRNAs (miRNAs) are potent regulators of gene expression that function in a variety of developmental and physiological processes by dampening the expression of their target genes at a post-transcriptional level. In many gene regulatory networks (GRNs), miRNAs function in a switch-like manner whereby their expression and activity elicit a transition from one stable pattern of gene expression to a distinct, equally stable pattern required to define a nascent cell fate. While the importance of miRNAs that function in this capacity are clear, we have less of an understanding of the cellular factors and mechanisms that ensure the robustness of this form of regulatory bistability. In a screen to identify suppressors of temporal patterning phenotypes that result from ineffective miRNA-mediated target repression, we identified pqn-59, an ortholog of human UBAP2L, as a novel factor that antagonizes the activities of multiple heterochronic miRNAs. Specifically, we find that depletion of pqn-59 can restore normal development in animals with reduced lin-4 and let-7-family miRNA activity. Importantly, inactivation of pqn-59 is not sufficient to bypass the requirement of these regulatory RNAs within the heterochronic GRN. The pqn-59 gene encodes an abundant, cytoplasmically-localized, unstructured protein that harbors three essential "prion-like" domains. These domains exhibit LLPS properties in vitro and normally function to limit PQN-59 diffusion in the cytoplasm in vivo. Like human UBAP2L, PQN-59's localization becomes highly dynamic during stress conditions where it re-distributes to cytoplasmic stress granules and is important for their formation. Proteomic analysis of PQN-59 complexes from embryonic extracts indicates that PQN-59 and human UBAP2L interact with orthologous cellular components involved in RNA metabolism and promoting protein translation and that PQN-59 additionally interacts with proteins involved in transcription and intracellular transport. Finally, we demonstrate that pqn-59 depletion reduces protein translation and also results in the stabilization of several mature miRNAs (including those involved in temporal patterning). These data suggest that PQN-59 may ensure the bistability of some GRNs that require miRNA functions by promoting miRNA turnover and, like UBAP2L, enhancing protein translation.

Stress granules in colorectal cancer: Current knowledge and potential therapeutic applications

Stress granules (SGs) represent important non-membrane cytoplasmic compartments, involved in cellular adaptation to various stressful conditions (e.g., hypoxia, nutrient deprivation, oxidative stress). These granules contain several scaffold proteins and RNA-binding proteins, which bind to mRNAs and keep them translationally silent while protecting them from harmful conditions. Although the role of SGs in cancer development is still poorly known and vary between cancer types, increasing evidence indicate that the expression and/or the activity of several key SGs components are deregulated in colorectal tumors but also in pre-neoplastic conditions (e.g., inflammatory bowel disease), thus suggesting a potential role in the onset of colorectal cancer (CRC). It is therefore believed that SGs formation importantly contributes to various steps of colorectal tumorigenesis but also in chemoresistance. As CRC is the third most frequent cancer and one of the leading causes of cancer mortality worldwide, development of new therapeutic targets is needed to offset the development of chemoresistance and formation of metastasis. Abolishing SGs assembly may therefore represent an appealing therapeutic strategy to re-sensitize colon cancer cells to anti-cancer chemotherapies. In this review, we summarize the current knowledge on SGs in colorectal cancer and the potential therapeutic strategies that could be employed to target them.

CacyBP/SIP promotes tumor progression by regulating apoptosis and arresting the cell cycle in osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone tumor in pediatric and adolescent patients. The calcyclin-binding protein/Siah-1-interacting protein (CacyBP/SIP) performs an essential function in cell proliferation and apoptosis. The present study investigated the effect of CacyBP/SIP in OS cell proliferation and apoptosis. CacyBP/SIP mRNA expression levels were evaluated in four OS cell lines by quantitative PCR. CacyBP/SIP expression was downregulated in Saos-2 cells using a lentivirus transfection system and the transfection efficiency was analyzed. The effects of CacyBP/SIP downregulation on Saos-2 cell proliferation and colony-formation ability were evaluated by MTT and colony-formation assays. The effect of CacyBP/SIP knockdown on Saos-2 cell cycle and apoptosis was analyzed by flow cytometry cell sorting. The Cancer Genome Atlas (TCGA) data was analyzed for validation. Human OS cell lines Saos-2, MG-63, HOS and U20S expressed CacyBP/SIP mRNA. CacyBP/SIP knockdown significantly inhibited cell proliferation and colony-formation ability. G₁/S phase arrest was induced by CacyBP/SIP downregulation, which also resulted in the downregulation of CDK and cyclins and the upregulation of p21. In addition, CacyBP/SIP downregulation induced Saos-2 cell apoptosis mediated by Bax and Bcl-2. High expression of CacyBP/SIP was significantly associated with poor prognosis in TCGA sarcoma database. Thus, CacyBP/SIP performs important functions in the proliferation and apoptosis of human OS cells.

MicroRNA-19a-3p inhibits the cellular proliferation and invasion of non-small cell lung cancer by downregulating UBAP2L

MicroRNAs (miRNAs) are increasingly recognized as important regulators of non-small cell lung cancer (NSCLC) progression by directly regulating their target genes. The aim of the present study was to assess the biological role of miR-19a-3p in NSCLC. It was revealed that miR-19a-3p expression was significantly downregulated in human NSCLC tissues and cell lines compared with normal tissues and lung epithelial cells. In addition, a lower miR-19a-3p expression was significantly associated with Tumor Node Metastasis stage and lymph node metastasis. Furthermore, the upregulation of miR-19a-3p in NSCLC cell lines significantly inhibited cell proliferation, migration and invasion, as determined using an MTT, colony formation, wound healing and transwell Matrigel invasion assays, respectively. A luciferase reporter assay and western blotting determined that ubiquitin associated protein 2 like (UBAP2L) was a direct target of miR-19a-3p and could be inhibited through the upregulation of miR-19a-3p in NSCLC. In addition, UBAP2L silencing induced similar effects to those observed following miR-19a-3p overexpression. The overexpression of UBAP2L partially reversed the effects of miR-19a-3p on NSCLC cell lines. Collectively, these data indicated that miR-19a-3p may serve as a tumor suppressor partly through the regulation of UBAP2L expression in NSCLC and that the targeting of miR-19a-3p may be a novel method for NSCLC treatment.

UBAP2L arginine methylation by PRMT1 modulates stress granule assembly. Cell Death Differ. 2020;27:227-241. [PMID: 31114027 PMCID: PMC7205891 DOI: 10.1038/s41418-019-0350-5]

Stress granules (SGs) are discrete assemblies of stalled messenger ribonucleoprotein complexes (mRNPs) that form when eukaryotic cells encounter environmental stress. RNA-binding proteins (RBPs) mediate their condensation by recruiting populations of mRNPs. However, the cellular and molecular mechanisms underlying the role of ubiquitin-associated protein 2-like (UBAP2L) in the regulation of SG dynamics remain elusive. Here, we show that UBAP2L is required for both SG assembly and disassembly. UBAP2L overexpression nucleated SGs under stress-null conditions. The UBAP2L Arg–Gly–Gly (RGG) motif was required for SG competence, and mediated the recruitment of SG components, including mRNPs, RBPs, and ribosomal subunits. The domain of unknown function (DUF) of UBAP2L-mediated interaction with ras GTPase-activating protein-binding protein (G3BP)1/2, and its deletion caused the cytoplasmic–nuclear transport of UBAP2L and G3BP1/2, thereby compromising SG formation. The protein arginine methyltransferase PRMT1 asymmetrically dimethylated UBAP2L by targeting the RGG motif. Increased arginine methylation blocked, whereas its decrease enhanced UBAP2L interactions with SG components, ablating and promoting SG assembly, respectively. These results provide new insights into the mechanisms by which UBAP2L regulates SG dynamics and RNA metabolism.

Upregulation of UBAP2L in Bone Marrow Mesenchymal Stem Cells Promotes Functional Recovery in Rats with Spinal Cord Injury

Post-translational modifications of cellular proteins with ubiquitin or ubiquitin-like proteins regulate many cellular processes, such as cell proliferation, differentiation, apoptosis, signal transduction, intercellular immune recognition, inflammatory response, stress response, and DNA repair. Nice4/UBAP2L is an important member in the family of ubiquitin-like proteins, and its biological function remains unknown. This study aimed to investigate the effect of UBAP2L on spinal cord injury (SCI). At first, rat bone marrow mesenchymal stem cells (BMSCs) were infected with adeno-associated virus to induce over-expression of Nice4. Subsequently, the infected BMSCs were transplanted into rats suffering from semi-sectioned SCI. The results showed that the over-expression of Nice4 significantly promoted the proliferation and differentiation of BMSCs. In addition, the transplantation of infected BMSCs into the injured area of SCI rats improved the function repair of SCI. Importantly, the immunohistochemical and hematoxylin-eosin staining and RT-PCR results showed that the number of neuronal cells, oligodendrocytes, and astrocytes was significantly increased in the injured area, along with significantly upregulated expression of cyclin D1 and p38 mitogen-activated protein kinase (MAPK). Meanwhile, the expression of caspase 3 protein was significantly down-regulated. In conclusion, the over-expression of Nice4 gene can promote the functional recovery in SCI rats by promoting cell proliferation and inhibiting apoptosis. The results of this study indicate an alternative option for the clinical treatment of SCI.

UBA2 promotes proliferation of colorectal cancer

Small ubiquitin-like modifier proteins are involved in tumorigenesis; however, the potential effects and functions of the family member ubiquitin-like modifier-activating enzyme 2 (UBA2) on colorectal cancer are not clear. The present study aimed to examine the effects of UBA2 on the proliferation of colorectal cancer cells in vitro and in vivo. The mRNA and protein expression levels of UBA2 in patients with colorectal cancer were measured by reverse transcription-quantitative polymerase chain reaction and immunohistochemistry, respectively. UBA2 expression levels in colorectal cancer tissues were significantly increased compared with the paracancerous normal tissues. The expression of UBA2 was also associated with higher stage colorectal cancer and poor prognosis. MTT and colony formation assays were used to examine proliferation in colorectal cancer cell lines. Flow cytometry was performed to examine the effects of UBA2 on the cell cycle and apoptosis of colorectal cancer cell lines and protein expression levels were examined by western blotting. Athymic nude mice were used to examine the ability of transfected colorectal cancer cells to form tumors in vivo. Downregulation of UBA2 inhibited the proliferation of colorectal cancer cell lines in vitro and in vivo through the regulation of cell cycle associated protein expression and apoptosis. Furthermore, downregulation of UBA2 decreased the expression levels of cyclin B1, B-cell lymphoma-2, phosphorylated protein kinase B and E3 ubiquitin-protein ligase MDM2 in colorectal cancer cells, whereas the expression levels of p21 and p27 were increased. UBA2 was demonstrated to serve an essential role in the proliferation of colorectal cancer and may be used as a potential biomarker to predict prognosis and as a therapeutic target in colorectal cancer.

Knockdown of Ubiquitin Associated Protein 2-Like (UBAP2L) Inhibits Growth and Metastasis of Hepatocellular Carcinoma

BACKGROUND The aim of this study was to explore the influence of ubiquitin associated protein 2-like (UBAP2L) on the growth and metastasis of hepatocellular carcinoma (HCC) and its potential underlying mechanism. MATERIAL AND METHODS UBAP2L gene was knocked down in SMMC-7721 by RNA interference and cell function experiments were performed. A subcutaneous xenograft tumor model was constructed to examine the effect of UBAP2L silence on HCC growth. Finally, the whole genomic microarrays were used to screen the potential mechanism of UBAP2L in regulating the biological function of HCC. RESULTS Compared with those in the control group, the cell proliferation and clone formation were significantly reduced, cell cycle was arrested in G2/M phase, the number of apoptotic cells was remarkably increased, and the abilities of vascular formation and cell migration and metastasis were dramatically weakened in the shUBAP2L group (All P<0.05). UBAP2L knockdown significantly suppressed the tumor growth of HCC in vivo. Moreover, a total of 320 genes changed significantly after UBAP2L knockdown, among which, 159 genes were upregulated and 161 genes were downregulated. Then, gene enrichment analysis revealed that PI3K/AKT and P53 signal pathway were the most significant in the top 10 enrichments. Finally, Western blot analysis verified that UBAP2L knockdown caused the increase of P21 and PTEN and decrease of CDK1, CCNB1, p-PI3K, and p-AKT. CONCLUSIONS UBAP2L plays an oncogenic role in HCC, and knockdown of its expression significantly inhibits HCC growth and metastasis, which may be related to the regulation of PI3K/AKT and P53 signaling pathways by UBAP2L.

UBAP2L silencing inhibits cell proliferation and G2/M phase transition in breast cancer

Background

Ubiquitin-associated protein 2-like (UBAP2L) contains a ubiquitin-associated domain near its N-terminus, which has been demonstrated to be overexpressed in multiple tumors, including hepatocellular carcinoma and colorectal carcinoma but its role has not been well studied in breast cancer. Thus, this study was designed to evaluate whether UBAP2L can serve as a potential molecular target for breast cancer therapy.

Methods

The expression of UBAP2L was determined in breast cancer tissues and cell lines by Western blotting and Oncomine database mining. Then the expression of UBAP2L was silenced using RNA interference and the effects of UBAP2L knockdown on breast cancer cell proliferation and cell cycle progression by MTT and colony formation assay, and Flow cytometry, respectively.

Results

We found the expression of UBAP2L was significantly up-regulated in breast cancer tissues and cell lines. Knockdown of UBAP2L suppressed cell proliferation, impaired colony formation ability and induced cell cycle arrest at G2/M phase. At molecular levels, knockdown of UBAP2L increased p21 expression, but decreased the expression of CDK1 and Cyclin B1 in breast cancer cells.

Conclusion

Our findings suggest that UBAP2L plays an important role in breast cancer cell proliferation and might serve as a potential target for breast cancer treatment.

Ubiquitin Associated Protein 2-Like (UBAP2L) Overexpression in Patients with Hepatocellular Carcinoma and its Clinical Significance

BACKGROUND Recently, accumulating studies have shown that ubiquitin associated protein 2-like (UBAP2L) is overexpressed in many kinds of malignant tumors, which is closely associated to tumor growth and metastasis. However, the correlations of UBAP2L expression with clinicopathological factors and prognosis of hepatocellular carcinoma (HCC) patients still remain unclear. MATERIAL AND METHODS Bioinformatics database (GEO and TCGA) and our own experimental results (including immunohistochemical staining, western blotting and real-time PCR) were analyzed to validate the expression levels of UBAP2L in HCC. Furthermore, Kaplan-Meier survival analysis and Cox multivariate regression model were used to demonstrate the associations of UBAP2L expression with clinicopathological factors and prognosis of HCC patients. Additionally, the potential underlying mechanisms associated to angiogenesis were preliminarily explored. RESULTS Compared to the normal group, UBAP2L was significantly highly expressed in HCC cell lines and tissues. Kaplan-Meier survival analysis revealed that patients with high UBAP2L expression level had dramatically less survival time than those with low UBAP2L expression level (p=0.000). Moreover, multivariate Cox regression analysis showed that UBAP2L high expression was an independently unfavorable prognostic parameter for OS of HCC patients (p=0.000). Additionally, Pearson correlation analysis showed that the relationship between UBAP2L expression and VEGF or MVD was significantly positive, respectively (r=0.460, p=0.000 and r=0.387, p=0.000). CONCLUSIONS UBAP2L was overexpressed in HCC, and patients with high UBAP2L expression had unfavorable prognosis. UBAP2L could be a new potential therapeutic target for HCC in the future.

UBAP2L is amplified in a large subset of human lung adenocarcinoma and is critical for epithelial lung cell identity and tumor metastasis

The ubiquitin-associated protein 2-like (UBAP2L) gene remains poorly studied in human and mouse development. UBAP2L interacts with the Polycomb group protein B lymphoma Mo-MLV insertion region 1 homolog (BMI1) and determines the activity of mouse hematopoietic stem cells in vivo Here we show that loss of Ubap2l leads to disorganized respiratory epithelium of mutant neonates, which die of respiratory failure. We also show that UBAP2L overexpression leads to epithelial-mesenchymal transition-like phenotype in a non-small cell lung carcinoma (NSCLC) cell line. UBAP2L is amplified in 15% of human primary lung adenocarcinoma specimens. Such patients express higher levels of UBAP2L and show a reduction in survival when compared with those who do not have this gene amplification. Supporting a possible role for UBAP2L in lung tumor progression, NSCLC cells engineered to express low levels of this gene produce much smaller tumors in vivo than wild-type control cells. Together, these results suggest that UBAP2L contributes to epithelial lung cell identity in mice and that it plays an important role in human lung adenocarcinoma.-Aucagne, R., Girard, S., Mayotte, N., Lehnertz, B., Lopes-Paciencia, S., Gendron, P., Boucher, G., Chagraoui, J., Sauvageau, G. UBAP2L is amplified in a large subset of human lung adenocarcinoma and is critical for epithelial lung cell identity and tumor metastasis.