WD Repeat Domain Research Articles

Up-regulated WDR5 promotes gastric cancer formation by induced cyclin D1 expression.

Gastric cancer (GC) is the fourth common cancer and second leading cause of cancer-related mortality in the world. WD repeat domain 5 (WDR5) has been identified that its functions as an important role in various biological functions through the epigenetic regulation of gene transcription. However, the oncogenic effect of WDR5 in gastric cancer remains largely unknown. In this study, we investigated the role of WDR5 in gastric cancer genesis. We found that WDR5 expression is increased in gastric cancer patients. Through survival analysis, we found that high expression of WDR5 is associated with high risk gastric cancer; patients who with WDR5 high expression have poor survival rate compared with those who with WDR5 low expression. To make further investigation, we identified that WDR5 is targeted for cell cycle arrest by the Cyclin D1 in a process that is regulated by H3K4me3. Moreover, over-expression of WDR5 promotes cell proliferation, induces S/G2/M arrest in cell cycle, and promotes the expression of WDR5 targets, as well as that of H3K4me3 on the promoter of its targets. Inversely, WDR5 knockdown by shRNA inhibits cell proliferation, reverses S/G2/M arrest in cell cycle, and suppresses the expression of WDR5 targets, as well as that of H3K4me3. We also observed the positive correlation of WDR5 expression with its target in the cohort study of gastric patients. Taken together, our data reveal that WDR5 may have oncogenic effect and WDR5-mediated H3K4 methylation plays an important role in gastric cancer.

Adenomatoid tumors of the male and female genital tract are defined by TRAF7 mutations that drive aberrant NF-kB pathway activation.

Adenomatoid tumors are the most common neoplasm of the epididymis, and histologically similar adenomatoid tumors also commonly arise in the uterus and fallopian tube. To investigate the molecular pathogenesis of these tumors, we performed genomic profiling on a cohort of 31 adenomatoid tumors of the male and female genital tracts. We identified that all tumors harbored somatic missense mutations in the TRAF7 gene, which encodes an E3 ubiquitin ligase belonging to the family of tumor necrosis factor receptor-associated factors (TRAFs). These mutations all clustered into one of five recurrent hotspots within the WD40 repeat domains at the C-terminus of the protein. Functional studies in vitro revealed that expression of mutant but not wildtype TRAF7 led to increased phosphorylation of nuclear factor-kappa B (NF-kB) and increased expression of L1 cell adhesion molecule (L1CAM), a marker of NF-kB pathway activation. Immunohistochemistry demonstrated robust L1CAM expression in adenomatoid tumors that was absent in normal mesothelial cells, malignant peritoneal mesotheliomas, and multilocular peritoneal inclusion cysts. Together, these studies demonstrate that adenomatoid tumors of the male and female genital tract are genetically defined by TRAF7 mutation that drives aberrant NF-kB pathway activation.

WD40 repeat domain proteins: a novel target class?

Antagonism of protein-protein interactions (PPIs) with small molecules is becoming more feasible as a therapeutic approach. Successful PPI inhibitors tend to target proteins containing deep peptide-binding grooves or pockets rather than the more common large, flat protein interaction surfaces. Here, we review one of the most abundant PPI domains in the human proteome, the WD40 repeat (WDR) domain, which has a central peptide-binding pocket and is a member of the β-propeller domain-containing protein family. Recently, two WDR domain-containing proteins, WDR5 and EED, as well as other β-propeller domains have been successfully targeted by potent, specific, cell-active, drug-like chemical probes. Could WDR domains be a novel target class for drug discovery? Although the research is at an early stage and therefore not clinically validated, cautious optimism is justified, as WDR domain-containing proteins are involved in multiple disease-associated pathways. The druggability and structural diversity of WDR domain binding pockets suggest that understanding how to target this prevalent domain class will open up areas of disease biology that have so far resisted drug discovery efforts.

Whole Genome Sequencing-Based Mapping and Candidate Identification of Mutations from Fixed Zebrafish Tissue.

As forward genetic screens in zebrafish become more common, the number of mutants that cannot be identified by gross morphology or through transgenic approaches, such as many nervous system defects, has also increased. Screening for these difficult-to-visualize phenotypes demands techniques such as whole-mount in situ hybridization (WISH) or antibody staining, which require tissue fixation. To date, fixed tissue has not been amenable for generating libraries for whole genome sequencing (WGS). Here, we describe a method for using genomic DNA from fixed tissue and a bioinformatics suite for WGS-based mapping of zebrafish mutants. We tested our protocol using two known zebrafish mutant alleles, gpr126st49 and egr2bfh227, both of which cause myelin defects. As further proof of concept we mapped a novel mutation, stl64, identified in a zebrafish WISH screen for myelination defects. We linked stl64 to chromosome 1 and identified a candidate nonsense mutation in the F-box and WD repeat domain containing 7 (fbxw7) gene. Importantly, stl64 mutants phenocopy previously described fbxw7vu56 mutants, and knockdown of fbxw7 in wild-type animals produced similar defects, demonstrating that stl64 disrupts fbxw7. Together, these data show that our mapping protocol can map and identify causative lesions in mutant screens that require tissue fixation for phenotypic analysis.

FBXW7 expression affects the response to chemoradiotherapy and overall survival among patients with oral squamous cell carcinoma: A single-center retrospective study.

FBXW7 (F-box and WD repeat domain containing-7) is a tumor suppressor protein that regulates the degradation of various oncoproteins in several malignancies. However, limited information is available regarding FBXW7 expression in oral squamous cell carcinoma. Therefore, this study aimed to determine the clinical significance of FBXW7 expression in oral squamous cell carcinoma. The FBXW7 expression patterns in oral squamous cell carcinoma and adjacent normal tissues from 15 patients who underwent radical resection were evaluated using quantitative real-time polymerase chain reaction and immunohistochemical staining. In addition, immunohistochemistry was performed using paraffin-embedded sections from biopsy specimens obtained from 110 patients with oral squamous cell carcinoma who underwent surgery after 5 fluorouracil-based chemoradiotherapy. The associations of FBXW7 expression with various clinicopathological features and prognosis were evaluated in these patients. As a results, in the 15 matched samples, the FBXW7 expression was significantly decreased in the oral squamous cell carcinoma tissues compared to that in the adjacent normal tissues. In the clinicopathological analysis, compared to high protein expression, low FBXW7 expression was found to significantly associate with a poor histological response to preoperative chemoradiotherapy. Kaplan-Meier curve analysis revealed that low FBXW7 expression was significantly associated with a poor prognosis, and FBXW7 expression was found to be an independent predictor of overall survival in the multivariate analysis. Our results suggest that FBXW7 may function as a tumor suppressor protein in oral squamous cell carcinoma. In addition, FBXW7 could be a potential biomarker for predicting not only the clinical response to chemoradiotherapy but also overall survival in patients with oral squamous cell carcinoma.

Crystal structure of the WD40 domain of human PRPF19

Human Pre-mRNA Processing factor 19 (hPRPF19) is an important component in human spliceosome machinery. hPRPF19 contains a WD40 repeats domain at its C-terminus, which is also conserved in yeast. Here we determined the crystal structure of the C-terminal WD40 repeat domain of hPRPF19 by X-ray crystallography. Our structural analysis revealed some significantly different structure features between the human and yeast Prp19 WD40 repeat domain. However, there are also conserved clusters of residues at the bottom surface of the fourth and the fifth WD40 repeats, which provides the important implication for the conserved Prp19 proteins in both human and yeast.

Disease Association and Druggability of WD40 Repeat Proteins.

WD40 repeat (WDR) domains are protein interaction scaffolds that represent one of the largest protein families in human, and a first WDR inhibitor-an allosteric antagonist of polycomb repressive complex 2-just entered the clinic. A systematic analysis of the CORUM database of protein complexes shows that WDR is the most represented domain in transcriptional regulation and one of the most prevalent in the ubiquitin proteasome system, two pathways of high relevance to drug discovery. Parsing the literature and the vulnerability of cancer cell lines to CRISPR knockout indicates that WDR proteins are targets of interest in oncology and other disease areas. A quantitative analysis of WDR structures reveals that druggable binding pockets can be found on multiple surfaces of these multifaceted protein interaction platforms. These data support the development of chemical probes to further interrogate WDR proteins as an emerging therapeutic target class.

The FOXA2 transcription factor is frequently somatically mutated in uterine carcinosarcomas and carcinomas.

Uterine carcinosarcomas (UCSs) are a rare but clinically aggressive form of cancer. They are biphasic tumors consisting of both epithelial and sarcomatous components. The majority of uterine carcinosarcomas are clonal, with the carcinomatous cells undergoing metaplasia to give rise to the sarcomatous component. The objective of the current study was to identify novel somatically mutated genes in UCSs. We whole exome sequenced paired tumor and nontumor DNAs from 14 UCSs and orthogonally validated 464 somatic variants using Sanger sequencing. Fifteen genes that were somatically mutated in at least 2 tumor exomes were Sanger sequenced in another 39 primary UCSs. Overall, among 53 UCSs in the current study, the most frequently mutated of these 15 genes were tumor protein p53 (TP53) (75.5%), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) (34.0%), protein phosphatase 2, regulatory subunit A, alpha (PPP2R1A) (18.9%), F-box and WD repeat domain containing 7 (FBXW7) (18.9%), chromodomain helicase DNA binding protein 4 (CHD4) (17.0%), and forkhead box A2 (FOXA2) (15.1%). FOXA2 has not previously been implicated in UCSs and was predominated by frameshift and nonsense mutations. One UCS with a FOXA2 frameshift mutation expressed truncated FOXA2 protein by immunoblotting. Sequencing of FOXA2 in 160 primary endometrial carcinomas revealed somatic mutations in 5.7% of serous, 22.7% of clear cell, 9% of endometrioid, and 11.1% of mixed endometrial carcinomas, the majority of which were frameshift mutations. Collectively, the findings of the current study provide compelling genetic evidence that FOXA2 is a pathogenic driver gene in the etiology of primary uterine cancers, including UCSs. Cancer 2018;124:65-73. © 2017 American Cancer Society.

Association of genetic variations in the lipid regulatory pathway genes FBXW7 and SREBPs with coronary artery disease among Han Chinese and Uygur Chinese populations in Xinjiang, China.

BackgroundHyperlipidemia is a major risk factor for coronary artery disease (CAD). The current study was designed to explore the possible correlation between single nucleotide polymorphisms (SNPs) in the lipid homeostasis regulatory genes F-box and WD repeat domain–containing 7 (FBXW7) and sterol regulatory element-binding proteins (SREBPs) with CAD among Han Chinese and Uygur Chinese populations in Xinjiang, China.ResultsIn the Uygur Chinese population, rs9902941 in SREBP-1 and rs10033601 in FBXW7 were found to be associated with CAD in a recessive model (TT vs. CT + CC, P = 0.032; GG vs. AG + AA, P = 0.010, respectively), and rs7288536 in SREBP-2 was found to be associated with CAD in an additive model (CT vs. CC + TT, P = 0.045). The difference was statistically significant in the Uygur Chinese population after multivariate adjustments [Odds ratio (OR) = 1.803, 95% confidence interval (CI): 1.036~3.137, P = 0.037; OR = 1.628, 95% CI: 1.080~2.454, P = 0.020; OR = 1.368; and 95% CI: 1.018~1.837, P = 0.037, respectively]. There were also significant interactions between the above-mentioned models in the Uygur Chinese population. However, these relationships were not observed before or after multivariate adjustment in the Han Chinese population.Materials and MethodsA total of 1,312 Han Chinese (650 CAD patients and 662 controls) and 834 Uygur Chinese (414 CAD patients and 420 controls) were enrolled in this case-control study. Three SNPs (rs9902941 in SREBP-1, rs7288536 in SREBP-2 and rs10033601 in FBXW7) were selected and genotyped using the improved multiplex ligase detection reaction (iMLDR) method.ConclusionsThe results of this study indicate that variations in the lipid regulatory pathway genes FBXW7 and SREBPs (rs9902941 in SREBP-1, rs7288536 in SREBP-2 and rs10033601 in FBXW7) are associated with CAD in the Uygur Chinese population in Xinjiang, China.

Cardiac transcriptome profiling of diabetic Akita mice using microarray and next generation sequencing.

Although diabetes mellitus (DM) causes cardiomyopathy and exacerbates heart failure, the underlying molecular mechanisms for diabetic cardiomyopathy/heart failure are poorly understood. Insulin2 mutant (Ins2+/-) Akita is a mouse model of T1DM, which manifests cardiac dysfunction. However, molecular changes at cardiac transcriptome level that lead to cardiomyopathy remain unclear. To understand the molecular changes in the heart of diabetic Akita mice, we profiled cardiac transcriptome of Ins2+/- Akita and Ins2+/+ control mice using next generation sequencing (NGS) and microarray, and determined the implications of differentially expressed genes on various heart failure signaling pathways using Ingenuity pathway (IPA) analysis. First, we validated hyperglycemia, increased cardiac fibrosis, and cardiac dysfunction in twelve-week male diabetic Akita. Then, we analyzed the transcriptome levels in the heart. NGS analyses on Akita heart revealed 137 differentially expressed transcripts, where Bone Morphogenic Protein-10 (BMP10) was the most upregulated and hairy and enhancer of split-related (HELT) was the most downregulated gene. Moreover, twelve long non-coding RNAs (lncRNAs) were upregulated. The microarray analyses on Akita heart showed 351 differentially expressed transcripts, where vomeronasal-1 receptor-180 (Vmn1r180) was the most upregulated and WD Repeat Domain 83 Opposite Strand (WDR83OS) was the most downregulated gene. Further, miR-101c and H19 lncRNA were upregulated but Neat1 lncRNA was downregulated in Akita heart. Eleven common genes were upregulated in Akita heart in both NGS and microarray analyses. IPA analyses revealed the role of these differentially expressed genes in key signaling pathways involved in diabetic cardiomyopathy. Our results provide a platform to initiate focused future studies by targeting these genes and/or non-coding RNAs, which are differentially expressed in Akita hearts and are involved in diabetic cardiomyopathy.

MicroRNA-223 promotes proliferation and migration of pancreatic cancer cell lines through downregulating F-box and WD repeat domain containing 7 expression

MicroRNA-223 promotes proliferation and migration of pancreatic cancer cell lines through downregulating F-box and WD repeat domain containing 7 expression

Long non-coding RNA CASC2 suppresses epithelial-mesenchymal transition of hepatocellular carcinoma cells through CASC2/miR-367/FBXW7 axis

BackgroundRecently, it has been reported that long non-coding RNA (lncRNA) cancer susceptibility candidate 2 (CASC2), a novel tumor suppressor, participates in regulating the carcinogenesis and suppresses tumor progression by sponging microRNAs (miRNAs). However, the expression and function of CASC2 in hepatocellular carcinoma (HCC) remain unclear.MethodsThe expression of CASC2 and miR-367 in HCC specimens and cell lines were detected by real-time PCR. Western blotting and immunohistochemistry were carried out for detection of epithelial-to-mesenchymal transition (EMT) markers in HCC. Transwell assays were used to determine migration and invasion of HCC cells. A mouse model for lung metastasis was established to evaluated HCC metastasis in vivo. The correlation among CASC2, miR-367 and F-box and WD repeat domain containing 7 (FBXW7) were disclosed by a dual-luciferase reporter assay, RIP assay and biotin pull-down assay.ResultsHere, CASC2 expression was significantly downregulated in HCC tissues, especially in aggressive and recurrent cases. In accordance, CASC2 underexpression was observed in HCC cell lines compared to LO2. In vitro and in vivo experiments revealed that CASC2 inhibited migration and invasion of HCC cells. Additionally, CASC2 repressed EMT process of HCC cells. Further studies demonstrated that CASC2 could function as a competing endogenous RNA (ceRNA) by sponging miR-367 in HCC cells. Functionally, gain- and loss-of-function studies showed that miR-367 promoted migration, invasion and EMT progression of HCC cells. Moreover, further investigations disclosed that FBXW7 was a downstream target of miR-367 and CASC2 prohibited EMT progression and subsequently exerted its anti-metastatic effects via CASC2/miR-367/FBXW7 axis in HCC cells. Clinically, CASC2 underexpression and miR-367 overexpression were closely correlated with the metastasis-associated clinicopathologic features. Notably, CASC2 low-expressing and miR-367 high-expressing HCC patients showed the poorest clinical outcome.ConclusionsOverall, we conclude that the CASC2/miR-367/FBXW7 axis may be a ponderable and promising therapeutic target for HCC.

Targeting FBW7 as a Strategy to Overcome Resistance to Targeted Therapy in Non-Small Cell Lung Cancer.

Inhibition of EGFR and anaplastic lymphoma kinase (ALK) signaling is highly effective in a subgroup of non-small cell lung cancer (NSCLC) patients with distinct clinicopathologic features. However, resistance to EGFR and ALK inhibitors inevitably occurs, and the molecular mechanism underlying resistance is not fully understood. In this study, we report a PI3K/Akt- and MEK/ERK-independent resistance mechanism by which loss of the E3 ubiquitin ligase F-box and WD repeat domain containing 7 (FBW7α) leads to targeted therapy resistance via stabilization of antiapoptotic protein MCL-1. Using a panel of in vitro and in vivo studies, we showed that the regulatory machinery responsible for MCL-1 protein degradation was a step-wise event involving phosphorylation and nucleus translocation. ERK cooperated with GSKβ to phosphorylate MCL-1 Ser159 residue, which enabled MCL-1 to translocate into the nucleus and bind FBW7. Defects in this sequence impaired MCL-1 degradation and cell apoptosis, recapitulating phenotypes observed in FBW7 deficiency. Downregulation of FBW7 was found in EGFR inhibitor-resistant human NSCLC specimens and correlated with increased MCL-1 protein expression. Reactivation of FBW7 sensitized resistant cells to targeted therapy and facilitated MCL-1 degradation. Overall, our study provides proof-of-principle insight into a PI3K/Akt- and MEK/ERK-independent resistant model and suggests that targeting FBW7 can overcome resistance to targeted therapy. Cancer Res; 77(13); 3527-39. ©2017 AACR.

Remarkable Evolutionary Conservation of Antiobesity ADIPOSE/WDTC1 Homologs in Animals and Plants.

ASG2 (Altered Seed Germination 2) is a prenylated protein in Arabidopsis thaliana that participates to abscisic acid signaling and is proposed to act as a substrate adaptor for the DDB1 (DNA damage-binding protein 1)-CUL4 (Cullin 4) E3 ubiquitin ligase complex. ASG2 harbors WD40 and TetratricoPeptide Repeat (TPR) domains, and resembles the well-conserved animal gene called ADP (antiobesity factor ADIPOSE) in fly and WDTC1 (WD40 and TPR 1) in humans. Loss of function of WDTC1 results in an increase in adipocytes, fat accumulation, and obesity. Antiadipogenic functions of WDTC1 involve regulation of fat-related gene transcription, notably through its binding to histone deacetylases (HDACs). Our sequence and phylogenetic analysis reveals that ASG2 belongs to the ADP/WDTC1 cluster. ASG2 and WDTC1 share a highly conserved organization that encompasses structural and functional motifs: seven WD40 domains and WD40 hotspot-related residues, three TPR protein-protein interaction domains, DDB1-binding elements [H-box and DWD (DDB1-binding WD40 protein)-box], and a prenylatable C-terminus. Furthermore, ASG2 involvement in fat metabolism was confirmed by reverse genetic approaches using asg2 knockout Arabidopsis plants. Under limited irradiance, asg2 mutants produce "obese" seeds characterized by increased weight, oil body density, and higher fatty acid contents. In addition, considering some ASG2- and WDTC1-peculiar properties, we show that the WDTC1 C-terminus is prenylated in vitro and HDAC-binding capability is conserved in ASG2, suggesting that the regulation mechanism and targets of ADP/WDTC1-like proteins may be conserved features. Our findings reveal the remarkable evolutionary conservation of the structure and the physiological role of ADIPOSE homologs in animals and plants.

LRWD1 Regulates Microtubule Nucleation and Proper Cell Cycle Progression in the Human Testicular Embryonic Carcinoma Cells.

Leucine-rich repeats and WD repeat domain containing protein 1 (LRWD1) is a testis-specific protein that mainly expressed in the sperm neck where centrosome is located. By using microarray analysis, LRWD1 is identified as a putative gene that involved in spermatogenesis. However, its role in human male germ cell development has not been extensively studied. When checking in the semen of patients with asthenozoospermia, teratozoospermia, and asthenoteratozoospermia, the level of LRWD1 in the sperm neck was significantly reduced with a defective neck or tail. When checking the sub-cellular localization of LRWD1 in the cells, we found that LRWD1 resided in the centrosome and its centrosomal residency was independent of microtubule transportation in NT2/D1, the human testicular embryonic carcinoma, cell line. Depletion of LRWD1 did not induce centrosome re-duplication but inhibited microtubule nucleation. In addition, the G1 arrest were observed in LRWD1 deficient NT2/D1 cells. Upon LRWD1 depletion, the levels of cyclin E, A, and phosphorylated CDK2, were reduced. Overexpression of LRWD1 promoted cell proliferation in NT2/D1, HeLa, and 239T cell lines. In addition, we also observed that autophagy was activated in LRWD1 deficient cells and inhibition of autophagy by chloroquine or bafilomycin A1 promoted cell death when LRWD1 was depleted. Thus, we found a novel function of LRWD1 in controlling microtubule nucleation and cell cycle progression in the human testicular embryonic carcinoma cells. J. Cell. Biochem. 119: 314-326, 2018. © 2017 Wiley Periodicals, Inc.

Evaluation of urinary autophagy transcripts expression in diabetic kidney disease

BackgroundWe identified and validated novel urinary autophagy markers in diabetic kidney disease (DKD) based on bioinformatics analysis and clinical validation. Patients & methodsWe retrieved three novel autophagy genes related to DKD from public microarray databases, namely; microtubule-associated protein light chain (MAP1LC3A), WD Repeat Domain, Phosphoinositide Interacting 2 (WIPI2), and RB1-Inducible Coiled-Coil 1 (RB1CC1). Secondly we assessed the expression of the chosen autophagy transcript in urine sediment of 86 patients with DKD and 74 (age and sex matched) controls by reverse transcription quantitative real-time PCR. ResultsThe urinary expression levels of MAP1LC3A, WIPI, RB1CC1 were significantly lower in DKD than control group (P<0.001).The receiver-operating characteristic curve (ROC) analyses that each urinary autophagy transcript showed high sensitivity and specificity for distinguishing DKD from control (MAP1LC3A, 81.4% and 81.1%; WIPI, 74.4% and 67.6%, and RB1CC1, 81.4%,70.3%, respectively). Notably, a negative correlation was found between these autophagy markers, serum creatinine and urinary albumin creatinine ratio. The sensitivity and specificity of this urinary autophagy based panel reached 90.6% and 60% in diagnosis of DKD. ConclusionWe identified and validated a novel diagnostic urinary autophagy based panel with high sensitivity and moderate specificity representing a vital player in the pathogenesis of DKD.

Discovery of a Highly Potent, Cell-Permeable Macrocyclic Peptidomimetic (MM-589) Targeting the WD Repeat Domain 5 Protein (WDR5)-Mixed Lineage Leukemia (MLL) Protein-Protein Interaction.

We report herein the design, synthesis, and evaluation of macrocyclic peptidomimetics that bind to WD repeat domain 5 (WDR5) and block the WDR5-mixed lineage leukemia (MLL) protein-protein interaction. Compound 18 (MM-589) binds to WDR5 with an IC50 value of 0.90 nM (Ki value <1 nM) and inhibits the MLL H3K4 methyltransferase (HMT) activity with an IC50 value of 12.7 nM. Compound 18 potently and selectively inhibits cell growth in human leukemia cell lines harboring MLL translocations and is >40 times better than the previously reported compound MM-401. Cocrystal structures of 16 and 18 complexed with WDR5 provide structural basis for their high affinity binding to WDR5. Additionally, we have developed and optimized a new AlphaLISA-based MLL HMT functional assay to facilitate the functional evaluation of these designed compounds. Compound 18 represents the most potent inhibitor of the WDR5-MLL interaction reported to date, and further optimization of 18 may yield a new therapy for acute leukemia.

Cell cycle-dependent degradation of the methyltransferase SETD3 attenuates cell proliferation and liver tumorigenesis

Histone modifications, including lysine methylation, are epigenetic marks that influence many biological pathways. Accordingly, many methyltransferases have critical roles in various biological processes, and their dysregulation is often associated with cancer. However, the biological functions and regulation of many methyltransferases are unclear. Here, we report that a human homolog of the methyltransferase SET (SU(var), enhancer of zeste, and trithorax) domain containing 3 (SETD3) is cell cycle-regulated; SETD3 protein levels peaked in S phase and were lowest in M phase. We found that the β-isoform of the tumor suppressor F-box and WD repeat domain containing 7 (FBXW7β) specifically mediates SETD3 degradation. Aligning the SETD3 sequence with those of well known FBXW7 substrates, we identified six potential non-canonical Cdc4 phosphodegrons (CPDs), and one of them, CPD1, is primarily phosphorylated by the kinase glycogen synthase kinase 3 (GSK3β), which is required for FBXW7β-mediated recognition and degradation. Moreover, depletion or inhibition of GSK3β or FBXW7β resulted in elevated SETD3 levels. Mutations of the phosphorylated residues in CPD1 of SETD3 abolished the interaction between FBXW7β and SETD3 and prevented SETD3 degradation. Our data further indicated that SETD3 levels positively correlated with cell proliferation of liver cancer cells and liver tumorigenesis in a xenograft mouse model, and that overexpression of FBXW7β counteracts the SETD3's tumorigenic role. We also show that SETD3 levels correlate with cancer malignancy, indicated by SETD3 levels that the 54 liver tumors are 2-fold higher than those in the relevant adjacent tissues. Collectively, these data elucidated that a GSK3β-FBXW7β-dependent mechanism controls SETD3 protein levels during the cell cycle and attenuates its oncogenic role in liver tumorigenesis.

Identification and validation of a novel autophagy gene expression signature for human bladder cancer patients.

We sought to identify and validate a novel urinary autophagy transcript signature in patients with bladder cancer and evaluate its clinical utility. We performed an initial screening for seven autophagy transcript-based panel (autophagy-related protein 12 (ATG12); WD repeat domain, phosphoinositide interacting 2 (WIPI2); FYVE and coiled-coil domain-containing protein 1 (FYCO1); microtubule-associated protein light chain (MAPLC3); RB1-inducible coiled-coil 1 (RB1CC1); tachylectin-II-like beta-propeller domain 1 (TECPR1); and Unc-51-like kinase (ULK1)) that was identified based on bioinformatics analysis followed by SYBR Green-based polymerase chain reaction array validation in paired tissue and urine samples. Afterward, we evaluated the expression of differentially expressed autophagy transcripts in an independent validation set with reverse transcription quantitative real-time polymerase chain reaction in urine sediments of 140 patients with bladder cancer, 68 patients with benign urological lesions, and 74 healthy controls (age and sex matched). The expression levels of ATG12, FYCO1, TECPR1, and ULK1 in paired bladder tissue and urine samples were significantly lower in bladder cancer than in control group (p < 0.001). In the validation set, the receiver-operating characteristic curve analyses demonstrated that each urinary autophagy transcripts showed high sensitivity and specificity for distinguishing bladder cancer from non-bladder cancer patients (ATG12, 75.4% and 86.1%; FYCO1, 87% and 75.7%; ULK1, 85.5% and 75.6%; and TECPR1, 90% and 81.9%). We document and validate a novel autophagy transcript signature for human bladder cancer diagnosis: bilharzial and non-bilharzial types.

CCCTC-Binding Factor Transcriptionally Targets Wdr5 to Mediate Somatic Cell Reprogramming.

It was previously reported that WD repeat domain 5 (Wdr5), a core member of the mammalian Trithorax complex, is a key regulator for the maintenance of embryonic stem (ES) cell pluripotency and somatic cell reprogramming. However, it remains unclear whether other factors are also involved in this process. Here, we show that CTCF is an upstream regulator of Wdr5: It physically associates with Wdr5 and further transcriptionally controls its expression by directly targeting the Wdr5 gene promoter. As a downstream effector, overexpression of Wdr5 can rescue ES cells from growth defects and decreased formation of induced pluripotent stem cells caused by CTCF knockdown. Our results reveal the functional relevance of CTCF and Wdr5, and they connect them to the re-establishment of pluripotency.