Ubiquitin-associated Protein 2-like Research Articles

UBAP2L contributes to formation of P-bodies and modulates their association with stress granules.

Stress triggers the formation of two distinct cytoplasmic biomolecular condensates: stress granules (SGs) and processing bodies (PBs), both of which may contribute to stress-responsive translation regulation. Though PBs can be present constitutively, stress can increase their number and size and lead to their interaction with stress-induced SGs. The mechanism of such interaction, however, is largely unknown. Formation of canonical SGs requires the RNA binding protein Ubiquitin-Associated Protein 2-Like (UBAP2L), which is a central SG node protein in the RNA-protein interaction network of SGs and PBs. UBAP2L binds to the essential SG and PB proteins G3BP and DDX6, respectively. Research on UBAP2L has mostly focused on its role in SGs, but not its connection to PBs. We find that UBAP2L is not solely an SG protein but also localizes to PBs in certain conditions, contributes to PB biogenesis and SG-PB interactions, and can nucleate hybrid granules containing SG and PB components in cells. These findings inform a new model for SG and PB formation in the context of UBAP2L's role.

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.

ALS-linked FUS R521C disrupts arginine methylation of UBAP2L and stress granule dynamics

Mutations in the fused-in-sarcoma (FUS) gene have been linked to familial amyotrophic lateral sclerosis (fALS). FUS aggregates in the cytosol and associates with stress granules (SGs) in pathological cases, whereas FUS is normally found in the nucleus. However, little is known about how FUS mutations cause neurodegeneration in ALS, which is distinguished by FUS-positive inclusion and stress granules. In this study, we investigated the mechanism of abnormal cytoplasmic aggregate formation caused by ALS-linked FUS mutations. FUS R521C interacted more with ubiquitin-associated protein 2-like (UBAP2L) and protein arginine methyltransferase 1 (PRMT1) than FUS WT, and PRMT1 and UBAP2L are sequestered into FUS R521C-positive stress granules under oxidative stress. PRMT1 asymmetrically demethylates UBAP2L, which is required for both SG assembly and disassembly. Furthermore, in FUS R521C, arginine methylation of UBAP2L is reduced, and the loss of PRMT1 increases FUS-positive SGs in oxidative stress. These results imply that an aberrant interaction between FUS-R521C and PRMT1 causes insufficient arginine methylation of UBAP2L, resulting in abnormal FUS-R521C-positive SGs remaining in the cytoplasm. This study could lead to the identification of a new pathogenic mechanism and therapeutic targets for the FUS mutation, which has been associated with abnormally increased protein interactions in ALS.Graphical abstract

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.

UBAP2L promotes gastric cancer metastasis by activating NF-\u03baB 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.

Ubiquitin-associated protein 2 like (UBAP2L) enhances growth and metastasis of gastric cancer cells

ABSTRACT Ubiquitin-proteasome pathway has emerged as therapeutic targets for cancer. GEPIA database analysis showed that the expression of ubiquitin-associated protein 2 like (UBAP2L) in gastric cancer specimens was significantly higher than that in non-tumor tissue, and its high expression is associated with poor survival of gastric cancer patients. This study aims to investigate the role of UBAP2L in gastric cancer. Real-time PCR and western blot results showed that UBAP2L expression was upregulated in gastric cancer cell lines. Loss- and gain-of-function experiments demonstrated that silencing of UBAP2L inhibited proliferation, migration and invasion, and induced apoptosis of gastric cancer cells, and overexpression of UBAP2L played opposite roles. Nude mice inoculated with UBAP2L-silenced gastric cancer cells generated smaller xenografted tumors in vivo. Furthermore, UBAP2L activated Wnt/β-catenin signaling – the accumulation of nuclear β-catenin and the expression of its downstream targets (cyclin D1, AXIN-2 and c-MYC) was facilitated, whereas knockdown of UBAP2L deactivated this signaling. The tumor-suppressing effect of UBAP2L silencing was abolished by forced activation of β-cateninS33A. UBAP2L has been confirmed as a novel and direct target of miR-148b-3p. The anti-tumor effect of miR-148b-3p was partly reversed by UBAP2L overexpression. The expression of miR-148b-3p was negatively correlated with that of UBAP2L in gastric cancer samples. Overall, our study indicates that UBAP2L is required to maintain malignant behavior of gastric cancer cells, which involves the activation of Wnt/β-catenin signaling pathway. We propose UBAP2L as a potential therapeutic target against gastric cancer.

Molecular Insights into the Recruiting Between UCP2 and DDX5/UBAP2L in the Metabolic Plasticity of Non-Small-Cell Lung Cancer.

Mitochondrial uncoupling protein 2 (UCP2) is distributed in tumor cells with a link to the support of systemic metabolic deregulation, and the downregulation of UCP2 has been unveiled as a biomarker of oncogenesis and chemoresistance in non-small-cell lung cancer (NSCLC) cells. However, the underlying mechanism of how UCP2 cooperates with other proteins in this metabolic reprogramming remains largely unsolved. We employed a combined computational and experimental strategy to explore into the recruiting of DDX5 with other proteins, and we unraveled the underlying structural mechanisms. We found that recruiting by ATP-dependent RNA helicase DDX5 (DDX5)/ubiquitin-associated protein 2-like (UBAP2L) might help UCP2 to play the pathological roles in NSCLC cells. According to the view of thermodynamics in physics, UCP2 tends to recruit DDX5 rather than UBAP2L, as shown by the ensemble-based docking, molecular dynamics simulations and molecular mechanics generalized Born surface area (MM/GBSA) approach. Cellular immunofluorescence assays further demonstrated that UCP2 associate with DDX5, and the recruiting of DDX5 with UCP2 at least partially contribute to the metabolic plasticity of NSCLCs via the AKT/mTOR pathway. Our study proposed an efficient way for detecting the protein-protein association via the experimentally validated molecular simulation. Our results shed light on the functional annotation of UCP and DDX family proteins in dysregulated metabolism, and the identification of candidate therapeutic targets for NSCLC.

Norcantharidin-blocked ANXA2P2 inhibits fibroblast proliferation by increasing UBAP2L mRNA stability through LIN28B

AimsNorcantharidin (NCTD) exhibits antitumor, anti-inflammatory, and anti-fibrosis properties, which makes NCTD an attractive candidate for the treatment of pathological scars. This study was designed to investigate the potential effects of NCTD on fibroblast proliferation and explore the underlying mechanisms. Materials and methodsFirst, cell viability and cell apoptosis were evaluated to determine the effects of NCTD on human skin fibroblasts, at 10, 50, and 100 μM. To explore the mechanism, bioinformatics analyses, chromatin immunoprecipitation, RNA immunoprecipitation, and RNA pulldown assays, and luciferase reporter assays were performed to verify the relationships among NCTD, signal transducer and activator of transcription 3 (STAT3), annexin A2 pseudogene 2 (ANXA2P2), and ubiquitin-associated protein 2-like (UBAP2L) mRNA in fibroblasts. Loss-of-function experiments were performed to investigate the roles played by STAT3, ANXA2P2, and UBAP2L in the proliferation and apoptosis of fibroblasts. Key findingsWe found that NCTD administration induced fibroblast apoptosis and inhibited fibroblast proliferation in a dose-dependent manner. Mechanistically, NCTD inhibited ANXA2P2 transcription through the inhibition of STAT3 phosphorylation. Subsequently, ANXA2P2 was found to enhance the physical interaction between UBAP2L mRNA and lin-28 homolog B (LIN28B), which increased the stability and levels of UBAP2L mRNA. Loss-of-function assays demonstrated that ANXA2P2 and UBAP2L knockdown induced fibroblast apoptosis and suppressed fibroblast proliferation. SignificanceIn conclusion, we confirmed that NCTD inhibits fibroblast proliferation by inhibiting the STAT3/ANXA2P2/UBAP2L axis, which suggested that NCTD could represent a new candidate for the treatment of pathological scars.

Large-scale tethered function assays identify factors that regulate mRNA stability and translation

The molecular functions of the majority of RNA-binding proteins (RBPs) remain unclear, highlighting a major bottleneck to a full understanding of gene expression regulation. Here, we develop a plasmid resource of 690 human RBPs that we subject to luciferase-based 3'-untranslated-region tethered function assays to pinpoint RBPs that regulate RNA stability or translation. Enhanced UV-cross-linking and immunoprecipitation of these RBPs identifies thousands of endogenous mRNA targets that respond to changes in RBP level, recapitulating effects observed in tethered function assays. Among these RBPs, the ubiquitin-associated protein 2-like (UBAP2L) protein interacts with RNA via its RGG domain and cross-links to mRNA and rRNA. Fusion of UBAP2L to RNA-targeting CRISPR-Cas9 demonstrates programmable translational enhancement. Polysome profiling indicates that UBAP2L promotes translation of target mRNAs, particularly global regulators of translation. Our tethering survey allows rapid assignment of the molecular activity of proteins, such as UBAP2L, to specific steps of mRNA metabolism.

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.

Clinical Significance of Ubiquitin-associated Protein 2-like in Patients With Uterine Cervical Cancer

Ubiquitin-associated protein 2-like (UBAP2L) has been demonstrated to be associated with the progression of multiple types of cancer. However, the function of UBAP2L in uterine cervical cancer remains unclear. Between 2005 and 2015, 84 patients who underwent surgery were included in this study. The patients were stratified into two groups on the basis of immunohistochemical staining for UBAP2L, and survival analysis was performed. Moreover, loss-of-function analysis was performed using the cervical cancer cell lines CaSki and SiHa. Based on immunohistochemistry, the overall survival in patients with low UBAP2L expression was significantly longer than that of those with high UBAP2L expression (p=0.045). The in vitro experiment revealed that knockdown of UBAP2L remarkably inhibited cell proliferation in both live cell imaging and the MTS assay. Patients with high UBAP2L expression had unfavorable prognosis and UBAP2L appears to play an important role in proliferation.

UBAP2L arginine methylation by PRMT1 modulates stress granule assembly

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.

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

BackgroundThe 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/MethodsUBAP2L 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.ResultsCompared 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.ConclusionsUBAP2L 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.

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

BackgroundRecently, 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/MethodsBioinformatics 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.ResultsCompared 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).ConclusionsUBAP2L 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.

Downregulation of UBAP2L Inhibits the Epithelial-Mesenchymal Transition via SNAIL1 Regulation in Hepatocellular Carcinoma Cells

Background/Aims: Dysregulation of ubiquitin-associated protein 2-like (UBAP2L) has been reported in tumors, but its role in hepatocellular carcinoma (HCC) progression is unclear. Methods: The expression levels of UBAP2L in HCC tissues and HCC cell lines were detected by western blot and quantitative real-time (qRT) PCR. The effects of UBAP2L expression on HCC cell biological traits, including migration and invasion, were investigated by wound healing assay and matrigel transwell assay. Simultaneously, the expression of epithelial-mesenchymal transition (EMT) markers including E-cadherin, CK-18, N-cadherin, Vimentin, Claudin7 and the promoter activity of E-cadherin were detected by western blot and qRT-PCR. Subsequently, role of SNAIL1 in UBAP2L-mediated EMT and the mechanism underlying UBAP2L-mediated SNAIL1 expression were further investigated. Results: UBAP2L was overexpressed in human HCC tissues compared with peri-tumoral tissues. Downregulation of UBAP2L inhibited migration, invasion and the EMT in highly metastatic HCC cell lines. Furthermore, UBAP2L knockdown inhibited expression of the transcriptional repressor SNAIL1 and its ability to bind to the E-cadherin promoter via SMAD2 signaling pathway, which in turn resulted in increased E-cadherin expression. Additionally, bioinformatics analysis showed that expression of UBAP2L is correlated with poor prognosis in patients with HCC. Conclusions: UBAP2L plays a critical role in maintenance of the metastatic ability of HCC cells via SNAIL1 Regulation and is predictive of a poor clinical outcome.

Arginine methylation of ubiquitin-associated protein 2-like is required for the accurate distribution of chromosomes.

Proper bioriented attachment of microtubules and kinetochores is essential for the precise distribution of duplicated chromosomes to each daughter cell. An aberrant kinetochore-microtubule attachment results in chromosome instability, which leads to cellular transformation or apoptosis. In this article, we show that ubiquitin-associated protein 2-like (UBAP2L) is necessary for correct kinetochore-microtubule attachment. Depletion of UBAP2L inhibited chromosome alignment in metaphase and delayed progression to anaphase by activating spindle assembly checkpoint signaling. In addition, UBAP2L knockdown increased side-on attachment of kinetochores along the microtubules and suppressed stable kinetochore fiber formation. A proteomics analysis identified protein arginine methyltransferase (PRMT)1 as a direct interaction partner of UBAP2L. UBAP2L has an arginine- and glycine-rich motif called the RGG/RG or GAR motif in the N terminus. Biochemical analysis confirmed that arginine residues in the RGG/RG motif of UBAP2L were directly methylated by PRMT1. Finally, we demonstrated that the RGG/RG motif of UBAP2L is essential for the proper alignment of chromosomes in metaphase for the accurate distribution of chromosomes. Our results show a possible role for arginine methylation in UBAP2L for the progression of mitosis.

Downregulation of ubiquitin-associated protein 2-like with a short hairpin RNA inhibits human glioma cell growth invitro.

Ubiquitin-associated protein 2-like (UBAP2L), which contains a ubiquitin-associated (UBA) domain near its N-terminus, has been indicated in the pathogenesis of several human cancers, including multiple myeloma, hepatocellular carcinoma and malignant ovarian tumors. However, the role of UBAP2L in human glioma remains unknown. In the present study, UBAP2L was widely expressed in multiple glioma cell lines. To further examine the effects of UBAP2L on glioma growth, lentivirus-mediated short hairpin RNA (shRNA) was employed to knockdown UBAP2L expression in the glioblastoma cell lines. Depletion of UBAP2L significantly inhibited the proliferation and colony formation ability, as determined by MTT and colony formation assays. Cell cycle analysis showed that UBAP2L knockdown induced G0/G1 phase arrest in U251 and U373 cells, while S phase arrest was induced in A172 cells. These results suggest that UBAP2L has a key role in glioma cell growth, and may act as an oncogene to promote malignant glioma development.

Knockdown of ubiquitin associated protein 2-like inhibits the growth and migration of prostate cancer cells.

The ubiquitin-proteasome system(UPS) is involved in the development of cancer in various functions. Inhibition of the ubiquitin-proteasome has been revealed to be a powerful therapeutic method for carcinoma. Ubiquitin associated protein 2-like(UBAP2L) is believed to be involved in the ubiquitin‑proteasome pathway; however, the role of UBAP2L in human prostate cancer is still unknown. In the present study, we found that UBAP2L was expressed in a number of prostate carcinoma cell lines. Using lentiviral-mediated RNA interference(RNAi), we efficiently knocked down endogenous UBAP2L expression at the mRNA and protein levels. After UBAP2L disruption, the proliferation and colony formation ability were significantly reduced in the PC-3 and DU145 cells. Flow cytometric analysis showed that UBAP2L knockdown blocked cell cycle progression. Downregulation of UBAP2L inhibited the migration of PC-3 and DU145 cells, as determined by Transwell assay. Moreover, depletion of UBAP2L blocked the AMPKα, Bad and PRAS40 signaling pathways. In conclusion, our results suggest that UBAP2L may play a role in prostate cancer growth and metastasis, and knockdown of UBAP2L by RNAi may serve as a potential therapeutic approach for prostate cancer.

Proteomic Characterization of Aggregating Proteins after the Inhibition of the Ubiquitin Proteasome System

Protein aggregation, which is associated with the impairment of the ubiquitin proteasome system, is a hallmark of many neurodegenerative diseases. To better understand the contribution of proteasome inhibition in aggregation, we analyzed which proteins may potentially localize in chemically induced aggregates in human neuroblastoma tissue culture cells. We enriched for proteins in high-density structures by using a sucrose gradient in combination with stable isotope labeling with amino acids in cell culture (SILAC). The quantitative analysis allowed us to distinguish which proteins were specifically affected by the proteasome inhibition. We identified 642 potentially aggregating proteins, including the p62/sequestosome 1 and NBR1 ubiquitin-binding proteins involved in aggregation. We also identified the ubiquitin-associated protein 2 like (UBAP2L). We verified that it cofractionated with ubiquitin in the high-density fraction and that it was colocalized in the ubiquitin-containing aggregates after proteasome inhibition. In addition, we identified several chaperone proteins and used data from protein interaction networks to show that they potentially interact with distinct subgroups of proteins within the aggregating structures. Several other proteins associated with neurodegenerative diseases, like UCHL1, were identified, further underlining the potential of our analysis to better understand the aggregation process and proteotoxic stress caused by proteasome inhibition.