Regulation of epithelial cell differentiation by the Ubiquitous expressed transcript isoform 1 in ulcerative colitis.

BACKGROUND AND AIM: Mucosal healing has emerged as a desirable treatment goal for patients with ulcerative colitis (UC). Healing of mucosal wounds involves epithelial cell proliferation and differentiation, and Y-box transcription factor ZONAB has recently been identified as the key modulator of intestinal epithelial restitution. METHODS: We studied the characteristics of UXT-V1 expression in UC patients using immunohistochemistry and qPCR. The functional role of UXT-V1 in the colonic epithelium was investigated using lentivirus-mediated shRNA in vitro and ex vivo. Through endogenous Co-immunoprecipitation and LC-MS/MS, we identified ZONAB as a UXT-V1-interactive protein. RESULTS: Herein, we report that UXT-V1 promotes differentiation of intestinal epithelial cells by regulating the nuclear translocation of ZONAB. UXT-V1 was upregulated in the intestinal epithelia of UC patients compared with that of healthy controls. Knocking down UXT-V1 in NCM-460 cells led to the enrichment of pathways associated with proliferation and differentiation. Furthermore, the absence of UXT-V1 in cultured intestinal epithelial cells and colonic organoids inhibited differentiation to the goblet cell phenotype. Mechanistically, the loss of UXT-V1 in the intestinal epithelial cells allowed nuclear translocation of ZONAB, wherein it regulated the transcription of differentiation-related genes, including AML1 and KLF4. CONCLUSION: Taken together, our study reveals a potential role of UXT-V1 in regulating epithelial cell differentiation, proving a molecular basis for mucosal healing in UC.

MYB regulates the SUMO protease SENP1 and its novel interaction partner UXT, modulating MYB target genes and the SUMO landscape.

SUMOylation is a post-translational modification frequently found on nuclear proteins, including transcription factors (TFs) and coactivators. By controlling the activity of several TFs, SUMOylation may have far-reaching effects. MYB is an example of a developmental TF subjected to SUMO-mediated regulation, through both SUMO conjugation and SUMO binding. How SUMO affects MYB target genes is unknown. Here, we explored the global effect of reduced SUMOylation of MYB on its downstream gene programs. RNA-Seq in K562 cells after MYB knockdown and rescue with mutants having an altered SUMO status revealed a number of differentially regulated genes and distinct gene ontology term enrichments. Clearly, the SUMO status of MYB both quantitatively and qualitatively affects its regulome. The transcriptome data further revealed that MYB upregulates the SUMO protease SENP1, a key enzyme that removes SUMO conjugation from SUMOylated proteins. Given this role of SENP1 in the MYB regulome, we expanded the analysis, mapped interaction partners of SENP1, and identified UXT as a novel player affecting the SUMO system by acting as a repressor of SENP1. MYB inhibits the expression of UXT suggesting that MYB is able not only to control a specific gene program directly but also indirectly by affecting the SUMO landscape through SENP1 and UXT. These findings suggest an autoactivation loop whereby MYB, through enhancing SENP1 and reducing UXT, is itself being activated by a reduced level of repressive SUMOylation. We propose that overexpressed MYB, seen in multiple cancers, may drive this autoactivation loop and contribute to oncogenic activation of MYB.

UXT at the crossroads of cell death, immunity and neurodegenerative diseases.

The ubiquitous expressed transcript (UXT), a member of the prefoldin-like protein family, modulates regulated cell death (RCD) such as apoptosis and autophagy-mediated cell death through nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), P53, P62, and methylation, and is involved in the regulation of cell metabolism, thereby affecting tumor progression. UXT also maintains immune homeostasis and reduces proteotoxicity in neuro-degenerative diseases through selective autophagy and molecular chaperones. Herein, we review and further elucidate the mechanisms by which UXT affects the regulation of cell death, maintenance of immune homeostasis, and neurodegenerative diseases and discuss the possible UXT involvement in the regulation of ferroptosis and immunogenic cell death, and targeting it to improve cancer treatment outcomes by regulating cell death and immune surveillance.

UXT attenuates the CGAS-STING1 signaling by targeting STING1 for autophagic degradation.

STING1 (stimulator of interferon response cGAMP interactor 1), the pivotal adaptor protein of CGAS (cyclic GMP-AMP synthase)-STING1 signaling, is critical for type I IFN production of innate immunity. However, excessive or prolonged activation of STING1 is associated with autoinflammatory and autoimmune diseases. Thus, preventing STING1 from over-activation is important to maintain immune homeostasis. Here, we reported that UXT (ubiquitously expressed prefoldin like chaperone), a small chaperone-like protein, was essential to prevent the excessive activation of STING1-mediated type I IFN signaling through autophagic degradation of STING1 via SQSTM1 (sequestosome 1). Upon DNA mimics or cyclic GMP-AMP (cGAMP) stimulation, UXT specifically interacted with STING1 and promoted STING1 degradation through selective macroautophagy/autophagy. Moreover, UXT was required for more efficient autophagic degradation of STING1 by facilitating the interaction of SQSTM1 and STING1. The in vivo role of UXT in attenuating the CGAS-STING1 signaling was further confirmed in the mouse model of DNA-virus infection and the TMPD (2,6,10,14-tetramethylpentadecane)-induced murine lupus model. Intriguingly, the expression of UXT was consistently impaired and exhibited a remarkable inverse correlation with type I IFN signature in the leukocytes and PBMCs (peripheral blood mononuclear cells) of several large SLE (systemic lupus erythematosus) cohorts. Importantly, the replenishment of UXT effectively suppressed the production of IFNs and ISGs in the PBMCs of SLE patients. Taken together, our study reveals a novel regulatory role of UXT in autophagic degradation of STING1 to maintain immune homeostasis. UXT might be a potential therapeutic target for alleviating aberrant type I IFNs in autoimmune diseasesAbbreviations: 3-MA: 3-methyladenine; BMDMs: bone marrow-derived macrophages; cGAMP: cyclic GMP-AMP; CGAS: cyclic gmp-amp synthase; cKO: conditional knockout; CXCL10: C-X-C motif chemokine ligand 10; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HSV-1: herpes simplex virus type 1; HTDNA: herring testes DNA; IFIT1: interferon induced protein with tetratricopeptide repeats 1; IFNA4: interferon alpha 4; IFNB: interferon beta; IRF3: interferon regulatory factor 3; ISD: interferon stimulatory DNA; ISGs: IFN-stimulated genes; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MEFs: mouse embryonic fibroblasts; RNA-seq: RNA sequencing; PBMCs: peripheral blood mononuclear cells; RSAD2: radical S-adenosyl methionine domain containing 2; SLE: systemic lupus erythematosus; SQSTM1: sequestosome 1; STING1: stimulator of interferon response cGAMP interactor 1; TBK1: TANK binding kinase 1; TMPD: 2,6,10,14-tetramethylpentadecane; UXT: ubiquitously expressed prefoldin like chaperone.

The role of UXT in tumors and prospects for its application in hepatocellular carcinoma.

UXT is widely expressed in human and mouse tissues and aberrantly expressed in various tumor tissues. UXT may play a pro-cancer or tumor suppressor role in different tumor types and microenvironments with different mechanisms of action. Studies have shown that UXT can interact with related receptors to exert its functions and affect tumor proliferation and metastasis, leading to a poor prognosis when the biological functions of these tumors are changed. Interestingly, the signaling pathways and mechanism-related molecules that interact with UXT are closely related to the occurrence of hepatocellular carcinoma (HCC) during disease progression. This article reviews the research progress of UXT and prospects for its application in HCC, with the aim of providing possible scientific suggestions for the basic research, diagnosis and treatment of HCC.

Patients with hepatocellular carcinoma (HCC) have a poor overall prognosis. Surgical resection is the preferred treatment option for HCC; however, most patients are already in the middle and late stages of the disease at the time of diagnosis. Surgical resection cannot achieve a therapeutic effect, and targeted therapy has become a feasible alternative. In this review we summarize the expression and mechanisms of action of the protein UXT in a variety of tumors and discuss its potential for future development as a therapeutic target to further improve the targeted therapy of HCC.

UXT, a novel DNMT3b-binding protein, promotes breast cancer progression via negatively modulating lncRNA MEG3/p53 axis.

Overexpressed ubiquitously expressed transcript (UXT) in breast tumors and derived cell lines modulated the transcriptional activity of estrogen receptor alpha. However, how UXT exerts its biological functions in the tumorigenicity of breast cancer remains largely unknown. Expressions of UXT and maternally expressed gene 3 (MEG3) were examined by qRT-PCR and Western blot. The capacity of cell proliferation, apoptosis, migration, and invasion was assessed using CCK-8, flow cytometry, and transwell assays. Methylation-specific PCR (MS-PCR) was employed to evaluate the methylation of the MEG3 imprinting control region. Co-immunoprecipitation was performed to verify the UXT/DNMT3b interaction. RNA immunoprecipitation (RIP) was subjected to assess the regulation of MEG3 on p53 activity. A xenograft tumor model was further conducted to certify the molecular mechanism. UXT was upregulated, while MEG3 was downregulated in breast cancer tissues and cell lines. UXT knockdown or MEG3 overexpression inhibited cell proliferation, promoted apoptosis, and weakened cell migration and invasion. Hypermethylation of the MEG3 imprinting control region was modulated by highly expressed DNMT3b. UXT inhibited MEG3 expression via recruiting DNMT3b to its imprinting control region. MEG3 positively regulated p53 activity. UXT negatively regulated the MEG3/p53 axis in a DNMT3b-dependent manner to promote tumor growth. UXT, a novel DNMT3b-binding protein, aggravates the progression of breast cancer through MEG3/p53 axis.

HOXD9 transcriptionally induced UXT facilitate breast cancer progression via epigenetic modification of RND3.

BACKGROUND: Ubiquitously expressed transcript (UXT) is a prefoldin-like protein. It was reported that UXT played vital role in several cancer types. However, functional role of UXT in breast cancer need further investigation. METHODS: mRNA level or protein level of were determined by qRT-PCR or western blots. Proliferation of breast cancer cells was evaluated by CCK-8 assay and EdU assay. Migrative and invasive ability of cells were determined by wound healing assay and transwell assay. Transcriptional activation of UXT was determined by dual luciferase activity. The enrichment of H3K27me3 and EZH2 on the promoter of RND3 was evaluated by ChIP assay. The methylation of RND3 promoter was determined by MSP assay. In vivo function of UXT was evaluated by xenograft model. RESULTS: Our results indicated that UXT was elevated in breast cancer and associated with poor prognosis. HOXD9 elevated expression of UXT via transcriptional activation. UXT knockdown impaired the proliferation, migration and invasion. Rescue experiments suggested that UXT promoted malignant phenotypes of breast cancer cells via epigenetically repressing RND3. Moreover, UXT promoted tumorigeneses and metastasis of breast cancer cell in vivo. CONCLUSION: Inhibition of UXT impaired proliferation and metastasis of cancer cell via promoting RND3. Moreover, UXT epigenetically repressed the expression of RND3 via recruiting EZH2 in the promoter of RND3.

UXT antisense RNA 1 sever as a novel prognostic long non-coding RNA in early stage pancreatic ductal adenocarcinoma patients after receiving pancreaticoduodenectomy.

Objective: The principal objective of this project was to investigate the prognostic value of UXT antisense RNA 1 (UXT-AS1) in pancreatic ductal adenocarcinoma (PDAC), as well as its biological function mechanisms and the screening of targeted drugs using The Cancer Genome Atlas (TCGA) PDAC genome-wide RNA sequencing (RNA-seq) dataset. Methods: We used TCGA 112 early stage PDAC patients to screen the prognostic value of UXT-AS1. Biological functions and mechanisms of UXT-AS1 were investigated by co-expression analysis, differentially expressed genes (DEGs) and gene set enrichment analysis, while targeted drug screening was investigated by connectivity Map (CMap). Results: By analyzing the dataset from TCGA cohort, we found that UXT-AS1 was significantly up-regulated in pancreatic cancer tissues. Multivariate survival analysis demonstrated that PDAC patients with high UXT-AS1 expression had an unfavourable prognosis (adjusted P=0.033, HR=1.830, 95%CI=1.051-3.188). Genome-wide co-expression analysis and gene set enrichment analysis suggested that UXT-AS1 may act as a pivotal part in PDAC by participating in nuclear factor kappa beta, regulation of tumor necrosis factor, cell adhesion, T cell receptor signaling pathway, and numerous immune-related biological processes and signaling pathways. Functional enrichment analysis of DEGs between high- and low-UXT-AS1 expression groups suggested that these DEGs were significant enriched in B cell receptor complex, response to drug chemical carcinogenesis and drug metabolism-cytochrome P450. CMap analysis revealed that quipazine and terazosin may be targeted drugs for UXT-AS1 in PDAC. Conclusion: Our current study has identified UXT-AS1 as a novel biomarker for the prognosis of early stage PDAC. We also clarified its biological functional mechanisms and identified two targeted drugs of UXT-AS1 in PDAC.

Depletion of UXT, a novel TSG101 interaction protein, leads to enhanced CEP55 attenuation through lysosome degradation.

The expression level of CEP55, a centrosome and midbody-associated protein is pivotal for cell cytokinesis and is significantly correlated with tumor stage. Our previous study demonstrated that ectopic expression of TSG101 can decrease androgen receptor expression level through the lysosome degradation pathway. Here, we further extended the investigation of TSG101 in modulating protein levels through lysosomes, and identified ubiquitously expressed transcript (UXT) to be a novel TSG101 interaction partner associated with TSG101-containing cytoplasmic vesicles. We also demonstrated that CEP55 can be recruited to TSG101 cytoplasmic vesicles resulting in downregulation of CEP55 through lysosome degradation. Moreover, UXT depletion promoted TSG101 vesicle-lysosome association and elevated autophagic carrier flux to enhance CEP55 degradation upon TSG101 overexpression. In summary, we identified a novel CEP55 regulation pathway mediated by TSG101 overexpression via lysosome degradation and revealed that UXT plays a role in the late endosome/autophagosome-lysosome fusion event, engaging in TSG101-mediated lysosome degradation.

Mice deficient in UXT exhibit retinitis pigmentosa-like features via aberrant autophagy activation.

UXT (ubiquitously expressed prefoldin like chaperone), a small chaperone-like protein, is widely expressed in diverse human and mouse tissues and is more abundant in retina and kidney. However, the functional characterization of UXT at tissue level was largely unknown. Here, we reported that mice deficient in UXT exhibited salient features of retinal degenerative disease, similar to retinitis pigmentosa. Conditional knockout (CKO) of Uxt led to retinal degeneration and pigmentation in mice retina along with significant alterations of retinitis pigmentosa-related genes, which indicated UXT might be associated with retinal degenerative disease sharing key features to retinitis pigmentosa. Consistently, the electroretinogram (ERG) responses were dramatically impaired in uxt CKO retinas. Strong degenerative features were observed in uxt CKO retinas, including specific and progressive reduction of photoreceptor cells and increased numbers of apoptotic cells. Intriguingly, macroautophagic/autophagic flux was enhanced in uxt CKO retina. Mechanistically, we found UXT was indispensable to suppress photoreceptor apoptotic cell death by inhibiting autophagy through regulating the activity of MTOR (mechanistic target of rapamycin kinase), a key negative regulator of autophagy. Conversely, knockdown of UXT induced the robust expression of the canonical autophagy-related genes and boosted autophagic flux and apoptosis, finally resulting in severe retina degeneration in uxt CKO mice. Taken together, our study reveals a vital role of UXT in preventing retina from degeneration. The loss of UXT results in a hyper-autophagic state leading to massive retinal degeneration. Therefore, UXT may be a crucial target for retinal degenerative disease.Abbreviations: 3-ma: 3-methyladenine; casp3: caspase 3; cko: conditional knockout; erg: electroretinogram; gapdh: glyceraldehyde-3-phosphate dehydrogenase; map1lc3b/lc3b: microtubule-associated protein 1 light chain 3; mtor: mechanistic target of rapamycin kinase; parp: poly (adp-ribose) polymerase family; rna-seq: rna sequencing; rp: retinitis pigmentosa; rps6kb1/s6k: ribosomal protein s6 kinase b1; sqstm1: sequestosome 1; tunel: terminal deoxynucleotidyl transferase mediated dutp nick-end labeling; uxt: ubiquitously expressed prefoldin like chaperone.

The E3 ubiquitin ligase SCF(Fbxo7) mediates proteasomal degradation of UXT isoform 2 (UXT-V2) to inhibit the NF-κB signaling pathway.

BACKGROUND: Ubiquitously eXpressed Transcript isoform 2 (UXTV2) is a prefoldin-like protein involved in NF-κB signaling, apoptosis, and the androgen and estrogen response. UXT-V2 is a cofactor in the NF-κB transcriptional enhanceosome, and its knockdown inhibits TNF-α -induced NF-κB activation. Fbxo7 is an F-box protein that interacts with SKP1, Cullin1 and RBX1 proteins to form an SCF(Fbxo7) E3 ubiquitin ligase complex. Fbxo7 negatively regulates NF-κB signaling through TRAF2 and cIAP1 ubiquitination. METHODS: We combine co-immunoprecipitation, ubiquitination in vitro and in vivo, cycloheximide chase assay, ubiquitin chain restriction analysis and microscopy to investigate interaction between Fbxo7 and overexpressed UXT-V2-HA. RESULTS: The Ubl domain of Fbxo7 contributes to interaction with UXTV2. This substrate is polyubiquitinated by SCF(Fbxo7) with K48 and K63 ubiquitin chain linkages in vitro and in vivo. This post-translational modification decreases UXT-V2 stability and promotes its proteasomal degradation. We further show that UXTV1, an alternatively spliced isoform of UXT, containing 12 additional amino acids at the N-terminus as compared to UXTV2, also interacts with and is ubiquitinated by Fbxo7. Moreover, FBXO7 knockdown promotes UXT-V2 accumulation, and the overexpression of Fbxo7-ΔF-box protects UXT-V2 from proteasomal degradation and enhances the responsiveness of NF-κB reporter. We find that UXT-V2 colocalizes with Fbxo7 in the cell nucleus. CONCLUSIONS: Together, our study reveals that SCF(Fbxo7) mediates the proteasomal degradation of UXT-V2 causing the inhibition of the NF-κB signaling pathway. GENERAL SIGNIFICANCE: Discovering new substrates of E3 ubiquitin-ligase SCF(Fbxo7) contributes to understand its function in different diseases such as cancer and Parkinson.

Methylation Profile of X-Chromosome-Related Genes in Male Breast Cancer.

Background: Androgen receptor (AR) has been described to play a prominent role in male breast cancer (MBC). It maps on chromosome X, and recent reports indicate that X-chromosome polysomy is frequent in MBC. Since the response to anti-androgen therapy may depend on AR polysomy and on its overexpression similarly to prostate cancer, the aim of the present study was to investigate the DNA methylation level of AR and its coregulators, especially those mapped on the X-chromosome, that may influence the activity of AR in MBC. Methods: The DNA methylation level of AR, MAGEA2, MAGEA11, MAGEC1, MAGEC2, FLNA, HDAC6, and UXT, mapped on the X-chromosome, was evaluated by quantitative bisulfite-NGS. Bioinformatic analysis was performed in a Galaxy Project environment using BWA-METH, MethylDackel, and Methylation Plotter tools. The study population consisted of MBC (41 cases) compared with gynecomastia (17 cases). Results: MAGEA family members, especially MAGEA2, MAGEA11, MAGEC, and UXT and HDAC6 showed hypomethylation of several CpGs, reaching statistical significance by the Kruskal-Wallis test (p < 0.01) in MBC when compared to gynecomastia. AR showed almost no methylation at all. Conclusions: Our study demonstrated for the first time that MAGEA family members mapped on the X-chromosome and coregulators of AR are hypomethylated in MBC. This may lead to their overexpression, enhancing AR activity.

Ubiquitous expressed transcript promotes tumorigenesis by acting as a positive modulator of the polycomb repressive complex 2 in clear cell renal cell carcinoma.

BACKGROUND: The ubiquitous expressed transcript (UXT) plays a key role in various tumors by regulating transcriptional activity of multiple transcription factors, including androgen receptor (AR). However, the role of UXT in clear cell renal cell carcinoma (ccRCC) is still unknown. METHODS: Yeast two-hybrid screening, GST pull-down and co-immunoprecipitation assays were performed to detect the interacting protein of UXT. Chromatin immunoprecipitation (ChIP) was performed to investigate the levels of histone H3 lysine 27 trimethylation at the HOXA9 promoters. CCK-8 assays, colony formation assays and Transwell assays were performed to detect the proliferation, colony formation, migration and invasion of renal cancer cells. Quantitative PCR analysis was performed to detect the expressions of UXT in human ccRCC samples. RESULTS: The enhancer of zeste homolog 2 (EZH2) is a novel UXT interacting protein and UXT interacts with EZH2 in the nucleus. In addition, UXT interacts with the polycomb repressive complex 2 (PRC2) through directly binding to EZH2 and suppressor of zeste 12 homolog (SUZ12), but not to embryonic ectoderm development (EED). Moreover, the UXT activates EZH2 histone methyltransferase activity by facilitating EZH2 binding with SUZ12. We further provided striking evidences that knockdown of UXT inhibits proliferation, colony formation, migration and invasion of renal cancer cells, in an EZH2-dependent manner. Importantly, the upregulation of UXT expression was observed in clinical ccRCC samples, and the high expression level of UXT was associated with advanced stage, distant metastasis and poor overall survival in patients with ccRCC. CONCLUSION: The UXT is a novel regulator of the PRC2 and acts as a renal cancer oncogene that affects the progression and survival of ccRCC patients.

Prostate-specific loss of UXT promotes cancer progression.

Ubiquitously-expressed, prefoldin-like chaperone (UXT) also called Androgen Receptor Trapped clone-27 (ART-27) is widely expressed in human tissues. Our previous studies showed that UXT regulates transcription repression including androgen receptor (AR) signaling in prostate cancer. Here we analyzed a tissue microarray consisting of normal prostate, benign prostatic hyperplasia, high grade prostatic intraepithelial neoplasia (HGPIN) and primary prostate cancer cases for UXT protein expression. We found that HGPIN and malignant tumors have significantly decreased UXT expression compared to the normal prostate. Loss of UXT expression in primary prostate cancer is positively associated with high Gleason grade and poor relapse-free survival. We engineered prostate-specific Uxt KO mice that developed a hyperplastic phenotype with apparent prostate secretion fluid blockage as well as PIN by 4-6 months. Doubly mutant Uxt KO /Pten KO mice developed a more aggressive PIN phenotype. UXT depletion in prostate cancer cells also increased retroelements expression, including LINE-1 and Alu. Consistent with this finding Uxt KO mice have increased LINE-1 protein levels in the prostate compared to control mice. In addition, cancer cells with UXT depletion have increased retrotransposition activity and accumulated DNA damage. Our findings demonstrate that loss of UXT is an early event during prostate cancer progression, which may contribute to genome instability.

Functional Contributions of Prefoldin to Gene Expression.

Prefoldin is a co-chaperone that evolutionarily originates in archaea, is universally present in all eukaryotes and acts as a co-chaperone by facilitating the supply of unfolded or partially folded substrates to class II chaperonins. Eukaryotic prefoldin is known mainly for its functional relevance in the cytoplasmic folding of actin and tubulin monomers during cytoskeleton assembly. However, the role of prefoldin in chaperonin-mediated folding is not restricted to cytoskeleton components, but extends to both the assembly of other cytoplasmic complexes and the maintenance of functional proteins by avoiding protein aggregation and facilitating proteolytic degradation. Evolution has favoured the diversification of prefoldin subunits, and has allowed the so-called prefoldin-like complex, with specialised functions, to appear. Subunits of both canonical and prefoldin-like complexes have also been found in the nucleus of yeast and metazoan cells, where they have been functionally connected with different gene expression steps. Plant prefoldin has also been detected in the nucleus and is physically associated with a gene regulator. Here we summarise information available on the functional involvement of prefoldin in gene expression, and discuss the implications of these results for the relationship between prefoldin structure and function.

Role of the PAQosome in Regulating Arrangement of Protein Quaternary Structure in Health and Disease.

The PAQosome, formerly known as the R2TP/PFDL complex, is an eleven-subunit cochaperone complex that assists HSP90 in the assembly of numerous large multisubunit protein complexes involved in essential cellular functions such as protein synthesis, ribosome biogenesis, transcription, splicing, and others. In this review, we discuss possible mechanisms of action and role of phosphorylation in the assembly of client complexes by the PAQosome as well as its potential role in cancer, ciliogenesis and ciliopathies.

Role of the Unconventional Prefoldin Proteins URI and UXT in Transcription Regulation.

The Unconventional prefoldin RPB5 interacting protein (URI), also known as RPB5-Mediating Protein (RMP) has been shown to play several regulatory roles in different cellular compartments including the mitochondria, as a phosphatase binding protein; in the cytoplasm, as a chaperone-like protein; and in the nucleus, as a transcriptional regulator through binding to RPB5 and RNA polymerase II (polII). This chapter focuses on the role URI plays in transcriptional regulation in the prostate cell. In prostate cells, URI is tightly bound to another prefoldin-like protein called UXT, a known androgen receptor (AR) cofactor. Part of a multiprotein complex, URI and UXT act as transcriptional repressors, and URI regulates KAP1 through PP2A phosphatase activity. The discovery of the interaction of URI and UXT with KAP1, AR, and PP2A, as well as the numerous interactions between URI and components of the R2TP/prefoldin-like complex, RPB5, and nuclear proteins involved in DNA damage response, chromatin remodeling and gene transcription, reveal a pleiotropic effect of the URI/UXT complex on nuclear processes. The mechanisms by which URI/UXT affect transcription, chromatin structure and regulation, and genome stability, remain to be elucidated but will be of fundamental importance considering the many processes affected by alterations of URI/UXT and other prefoldins and prefoldin-like proteins.

UXT-AS1-induced alternative splicing of UXT is associated with tumor progression in colorectal cancer.

Increasing evidence indicates that long non-coding RNAs (lncRNAs) can act as crucial regulators of tumor progression. In the present study, UXT-AS1 was found to be significantly upregulated in colorectal cancer (CRC) and high expression levels of UXT-AS1 were significantly associated with poor prognosis in CRC patients. In addition, upregulation of UXT-AS1 resulted in inhibition of cell apoptosis and the promotion of cell proliferation. Moreover, by regulating the alternative splicing of UXT, upregulation of UXT-AS1 decreased the UXT1 transcript which promoted cell apoptosis and increased the UXT2 transcript which promoted cell proliferation. Thus, aberrant high expression of UXT-AS1 can promote CRC progression by changing the alternative splicing of UXT from the UXT1 transcript to the UXT2 transcript. In conclusion, our findings suggest that the regulation of CRC progression is by UXT-AS1-induced alternative splicing of UXT, and the expression level of UXT-AS1 may be a potential prognostic biomarker and therapy target in CRC patients.

UXT Is a LOX-PP Interacting Protein That Modulates Estrogen Receptor Alpha Activity in Breast Cancer Cells.

The lysyl oxidase proenzyme propeptide region (LOX-PP) is a tumor suppressor protein whose mechanism of action is not completely understood. Here, the Ubiquitously expressed Transcript (UXT) was identified in a yeast two-hybrid assay with LOX-PP as bait and confirmed as a novel LOX-PP associating protein. UXT, a prefoldin-like protein, is ubiquitous in human and mouse. Since UXT modulates androgen receptor transcriptional activity in prostate cancer, we studied its role in breast cancer. Breast tumors and derived cell lines overexpressed UXT. UXT was able to associate with the estrogen receptor alpha (ER) and decrease its transcriptional activity and target gene expression. Conversely, UXT knockdown increased ER element-dependent transcriptional activity. Ectopic LOX-PP relocalized UXT to the cytoplasm and decreased its stability. UXT ubiquitination and depletion in the presence of LOX-PP was rescued by a proteasomal inhibitor. In summary, proteasome-mediated turnover of UXT upon interaction with LOX-PP releases repression of ER transcriptional activity. J. Cell. Biochem. 118: 2347-2356, 2017. © 2017 Wiley Periodicals, Inc.

The EZH1-SUZ12 complex positively regulates the transcription of NF-κB target genes through interaction with UXT.

Unlike other members of the polycomb group protein family, EZH1 has been shown to positively associate with active transcription on a genome-wide scale. However, the underlying mechanism for this behavior still remains elusive. Here, we report that EZH1 physically interacts with UXT, a small chaperon-like transcription co-activator. UXT specifically interacts with EZH1 and SUZ12, but not EED. Similar to upon knockdown of UXT, knockdown of EZH1 or SUZ12 through RNA interference in the cell impairs the transcriptional activation of nuclear factor (NF)-κB target genes induced by TNFα. EZH1 deficiency also increases TNFα-induced cell death. Interestingly, chromatin immunoprecipitation and the following next-generation sequencing analysis show that H3K27 mono-, di- and tri-methylation on NF-κB target genes are not affected in EZH1- or UXT-deficient cells. EZH1 also does not affect the translocation of the p65 subunit of NF-κB (also known as RELA) from the cytosol to the nucleus. Instead, EZH1 and SUZ12 regulate the recruitment of p65 and RNA Pol II to target genes. Taken together, our study shows that EZH1 and SUZ12 act as positive regulators for NF-κB signaling and demonstrates that EZH1, SUZ12 and UXT work synergistically to regulate pathway activation in the nucleus.