WTAP regulates DDX3Y mRNA via m6A modification to promote high glucose-induced podocytes injury and diabetic nephropathy progression.

Apoptosis of vascular smooth muscle cells (SMC) is a culprit event in atherosclerotic plaque destabilization. We recently discovered that Wilms’ tumor 1-associating protein (WTAP) is a dynamically expressed transcriptional regulator that can be pro-apoptotic for human SMCs (Circ Res, 2006). To identify upstream regulators of this nuclear protein, we screened growth factors for their capacity to impact WTAP expression and found that insulin-like growth factor-1 (IGF-1), a potent survival factor for SMCs, stimulated a striking decline in WTAP protein abundance, to 10% at 12 h. We further determined that this decline in WTAP was due specifically to WTAP protein degradation, established by pulse-chase analysis of 35 S-labeled WTAP and the absence of an acute effect of IGF-1 on WTAP mRNA abundance. IGF-1-mediated WTAP degradation was blocked by two mechanistically distinct IGF-1 receptor inhibitors (picropodophyllin and PQ401) and by inhibition of phosphatidylinositol 3 (PI3)-kinase but not by MEK inhibition. In addition, IGF-1 induced the association of WTAP with ubiquitin, established by coimmunoprecipitation, and the downregulation of WTAP by IGF-1 was abrogated by inhibiting 26S proteasome activity with lactacystin or MG132. Interestingly, IGF-1 also stimulated phosphorylation of WTAP, that preceded the association of WTAP with ubiquitin, and hyperphosphorylation of WTAP through phosphatase-inhibition further accelerated WTAP degradation. Finally, to determine if WTAP downregulation was necessary for IGF-1-mediated SMC survival, surface expression of phosphatidylserine was quantified by flow cytometry of SMCs infected with retrovirus containing WTAP cDNA. Whereas IGF-1 enhanced the survival of vector-infected SMCs this was completely abrogated in WTAP-overexpressing SMCs. Conclusions: IGF-1-mediated SMC survival is dependent on the rapid depletion of WTAP from the nucleus, a degradation cascade that is heralded by WTAP phosphorylation. This WTAP phosphorylation and clearance response represents a novel consequence of PI3-kinase activation and highlights WTAP as a key negative regulator of SMC survival during vascular remodeling.

Modification of the hepatitis C virus (HCV) positive-strand RNA genome by N6-methyladenosine (m6A) regulates the viral life cycle. This life cycle takes place solely in the cytoplasm, while m6A addition on cellular mRNA takes place in the nucleus. Thus, the mechanisms by which m6A is deposited on the viral RNA have been unclear. In this work, we find that m6A modification of HCV RNA by the m6A-methyltransferase proteins methyltransferase-like 3 and 14 (METTL3 and METTL14) is regulated by Wilms' tumor 1-associating protein (WTAP). WTAP, a predominantly nuclear protein, is an essential member of the cellular mRNA m6A-methyltransferase complex and known to target METTL3 to mRNA. We found that HCV infection induces localization of WTAP to the cytoplasm. Importantly, we found that WTAP is required for both METTL3 interaction with HCV RNA and m6A modification across the viral RNA genome. Further, we found that WTAP, like METTL3 and METTL14, negatively regulates the production of infectious HCV virions, a process that we have previously shown is regulated by m6A. Excitingly, WTAP regulation of both HCV RNA m6A modification and virion production was independent of its ability to localize to the nucleus. Together, these results reveal that WTAP is critical for HCV RNA m6A modification by METTL3 and METTL14 in the cytoplasm. IMPORTANCE Positive-strand RNA viruses such as HCV represent a significant global health burden. Previous work has described that HCV RNA contains the RNA modification m6A and how this modification regulates viral infection. Yet, how this modification is targeted to HCV RNA has remained unclear due to the incompatibility of the nuclear cellular processes that drive m6A modification with the cytoplasmic HCV life cycle. In this study, we present evidence for how m6A modification is targeted to HCV RNA in the cytoplasm by a mechanism in which WTAP recruits the m6A-methyltransferase METTL3 to HCV RNA. This targeting strategy for m6A modification of cytoplasmic RNA viruses is likely relevant for other m6A-modified positive-strand RNA viruses with cytoplasmic life cycles such as enterovirus 71 and SARS-CoV-2 and provides an exciting new target for potential antiviral therapies.

Acute myeloid leukemia (AML) is a heterogenous disease and the survival of AML patients is largely attributed to the improvement of supportive treatment. Wilms' tumor 1-associated protein (WTAP) is a nuclear protein functions in many physiological and pathological processes. Although its expression and function in many malignant diseases have been reported, its prognostic and epigenetic roles in AML are largely unknown. Peripheral blood or bone marrow samples were collected from AML patients. The WTAP expression was detected by western blot. WTAP expression level and patients clinical features were analyzed using statistical methods. WTAP knockdown AML cells were constructed. The experiments on proliferation, tumorigenic ability, cell cycle, and apoptosis were performed. Transcriptome sequencing was performed and analyzed. M6A methylation level was measured and m6A-RIP was performed to quantify m6A methylation level of MYC mRNA. RNA stability assay was performed to measure the half-life of mRNA. WTAP was overexpressed in AML patients and was an independent poor-risk factor in AML (p = 0.0140). Moreover, we found that WTAP regulated proliferation, tumorigenesis, cell cycle, and differentiation of AML cells. Furthermore, WTAP made AML cells resistant to daunorubicin. In further investigations, m6A methylation level was downregulated when knocking down WTAP, and c-Myc was upregulated due to the decreased m6A methylation of MYC mRNA. High WTAP expression predicts poor prognosis in AML and WTAP plays an epigenetic role in AML.

Aim: Wilms' tumor 1-associating protein (WTAP), plays a part in colorectal cancer (CRC) progression. However, it is not yet known how WTAP affects cancer progression by influencing leukocyte rich repeat containing proteins (NLR) - family members 3 (NLRP3) - related inflammasomes.Materials & methods: We first validated the expression of WTAP in CRC at the tissue and cellular levels. Subsequently, by transfecting si-NC and si-WTAP into cells, we verified functions of WTAP in proliferation, invasion, migration and apoptosis of CRC cells. Finally, we analyzed the N6-methyladenosine (m6A) modification of NLRP3 by WTAP using methylated RNA immunoprecipitation (MeRIP)-qPCR technology, confirming that WTAP mediated the repression of NLRP3 inflammasome and the malignant progression of tumor cells.Results: WTAP was substantially upregulated in CRC tissues and cells. WTAP reinforced the migration, proliferation and invasion ability of CRC cells, and repressed apoptosis. Mechanistically, WTAP mediated the m6A modification of NLRP3, which suppressed the expression of NLRP3 and dampened the NLRP3/Caspase-1/GSDMD axis activation as well as pyroptosis, thereby facilitating the malignant progression of CRC.Conclusion: WTAP mediates m6A modification to modulate the repression of the NLRP3/Caspase-1/GSDMD axis in pyroptosis, reinforcing the malignant progression of CRC.

BackgroundN6-methyladenosine (m6A) methylation, a well-known modification with new epigenetic functions, has been reported to participate in the tumorigenesis of hepatocellular carcinoma (HCC), providing novel insights into the molecular pathogenesis of this disease. However, as the key component of m6A methylation, Wilms tumor 1-associated protein (WTAP) has not been well studied in HCC. Here we investigated the biological role and underlying mechanism of WTAP in liver cancer.MethodsWe determined the expression of WTAP and its correlation with clinicopathological features using tissue microarrays and the Cancer Genome Atlas (TCGA) dataset. And we clarified the effects of WTAP on HCC cells using cell proliferation assay, colony formation, Edu assay and subcutaneous xenograft experiments. We then applied RNA sequencing combined with gene expression omnibus (GEO) data to screen candidate targets of WTAP. Finally, we investigated the regulatory mechanism of WTAP in HCC by m6A dot blot assay, methylated RNA immunoprecipitation (MeRIP) assay, dual luciferase reporter assay, RNA immunoprecipitation (RIP) assay and Chromatin immunoprecipitation (ChIP) assay.ResultsWe demonstrated that WTAP was highly expressed in HCC which indicated the poor prognosis, and that WTAP expression served as an independent predictor of HCC survival. Functionally, WTAP promoted the proliferation capability and tumor growth of HCC cells in vitro and in vivo. Furthermore, ETS proto-oncogene 1 (ETS1) was identified as the downstream effector of WTAP. The m6A modification regulated by WTAP led to post-transcriptional suppression of ETS1, with the implication of Hu-Antigen R (HuR) as an RNA stabilizer. Then ETS1 was found to inhibit the progression of HCC and could rescue the phenotype induced by WTAP deficiency. Moreover, WTAP modulated the G2/M phase of HCC cells through a p21/p27-dependent pattern mediated by ETS1.ConclusionWe have identified that WTAP is significantly up-regulated in HCC and promotes liver cancer development. WTAP-guided m6A modification contributes to the progression of HCC via the HuR-ETS1-p21/p27 axis. Our study is the first to report that WTAP-mediated m6A methylation has a crucial role in HCC oncogenesis, and highlights WTAP as a potential therapeutic target of HCC treatment.

Esophageal squamous cell carcinoma (ESCC) represents a frequently seen malignancy with high prevalence worldwide. Although current studies have shown that Wilms' tumor 1-associated protein (WTAP), a major part in the methyltransferase complex, is involved in various tumor pathological processes, its specific role in ESCC remains unclear. Therefore, the present work focused on exploring WTAP's function and mechanism in ESCC progression using clinical ESCC specimens, ESCC cells, and mammalian models. Firstly, we proved WTAP was significantly upregulated within ESCC, and WTAP mRNA expression showed a good diagnostic performance for ESCC. Functionally, WTAP positively regulated in-vivo and in-vitro ESCC cells' malignant phenotype through the AKT-mTOR signaling pathway. Meanwhile, WTAP positively regulated the N6-methyladenosine (m6A) modification levels in ESCC cells. Protein tyrosine phase type IVA member 1 (PTP4A1) was confirmed to be the m6A target of WTAP, and WTAP positively regulated the expression of PTP4A1. Further study revealed that PTP4A1 showed high expression within ESCC. Silencing PTP4A1 inhibited the AKT-mTOR signaling pathway to suppress ESCC cells' proliferation. Rescue experiments showed that silencing PTP4A1 partially reversed the WTAP-promoting effect on ESCC cells' proliferation ability. Mechanistically, WTAP regulated PTP4A1 expression to activate the AKT-mTOR pathway, promoting the proliferation of ESCC cells. Our study demonstrated that WTAP regulates the progression of ESCC through the m6A-PTP4A1-AKT-mTOR signaling axis and that WTAP is a potential target for diagnosing and treating ESCC.

Purpose: Wilms' tumor 1-associating protein (WTAP) which is known for its role in RNA methylation machinery, is highly upregulated in the necrotic region of glioblastoma multiforme (GBM). The highly heterogenic nature of GBM is associated with the necrotic region within the brain, where many types of cells such as the stromal cell, immune cells, and cancer stem cells co-localize. The complex cellular network within the necrotic region is believed to cause the resistance of the conventional chemotherapy and radiotherapy. Here we attempted to identify the role of WTAP in GBM and what kind of RNA modification is associated with the proliferation and stemness in GBM. Improvement of our understanding about post-transcriptional regulation in GBM will allow us to find out the key oncogenic switch in GBM, and development of therapeutics targeting this mechanism will provide better survival benefits. Methods: 23 Patient-derived cell lines, two established GBM cell lines, and astrocyte was arrayed to find out the correlation between WTAP and cancer stem cells. shWTAP and WTAP overexpression vector were infected into patient-derived GBM cancer stem cell lines to test the effect of WTAP. Western blot and polymerase chain reaction analysis was performed to find out the change in genes which are related to cell proliferation and stemness. Limiting dilution assay was performed to validate the function of WTAP in sphere-forming ability. RNA sequencing was performed on shWTAP infected patient-derived cancer stem cell to identify the type of RNA modification made by knocking down WTAP. Results: Knocking down of WTAP using shWTAP in patient-derived cancer stem cell lines, we were able to see the decrease in cell proliferation and stemness-related genes while overexpressing WTAP in these cells slightly increased cell proliferation and stemness. WTAP knockdown cells had a significant decrease in sphere-forming ability. RNA sequencing of shWTAP cells has revealed the increase in intron retention and the decrease in exon skipping, which shows that WTAP has a role in decreasing intron retention while increasing exon skipping. Conclusion: We have revealed that WTAP has an important role in increasing proliferation and maintaining stemness in GBM. We have also identified that WTAP decreases intron retention and increasing exon skipping. Citation Format: Sae Whan Park, Young Taek Oh, Jong Bae Park, Jong Heon Kim. Wilms' tumor 1-associating protein increases cancer cell proliferation and stem-cell like properties through RNA modification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4442.

Pancreatic cancer (PC) is a common malignant tumor of the digestive system, and its 5-year survival rate is only 4%. N6-methyladenosine (m6A) RNA methylation is the most common post-transcriptional modification and dynamically regulates cancer development, while its role in PC treatment remains unclear. We treated PC cells with gemcitabine and quantified the overall m6A level with m6A methylation quantification. Real-time quantitative reverse transcription polymerase chain reaction and Western blot analyses were used to detect expression changes of m6A regulators. We verified the m6A modification on the target genes through m6A-immunoprecipitation (IP), and further in vivo experiments and immunofluorescence (IF) assays were applied to verify regulation of gemcitabine on Wilms' tumor 1-associated protein (WTAP) and MYC. Gemcitabine inhibited the proliferation and migration of PC cells and reduced the overall level of m6A modification. Additionally, the expression of the "writer" WTAP was significantly downregulated after gemcitabine treatment. We knocked down WTAP in cells and found target gene MYC expression was significantly downregulated, m6A-IP also confirmed the m6A modification on MYC. Our experiments showed that m6A-MYC may be recognized by the "reader" IGF2BP1. In vivo experiments revealed gemcitabine inhibited the tumorigenic ability of PC cells. IF analysis also showed that gemcitabine inhibited the expression of WTAP and MYC, which displayed a significant trend of co-expression. Our study confirmed that gemcitabine interferes with WTAP protein expression in PC, reduces m6A modification on MYC and RNA stability, thereby inhibiting the downstream pathway of MYC, and inhibits the progression of PC.

BackgroundOsteoarthritis (OA) poses a significant risk to the mobility of patients. Carbonic anhydrase 12 (CA12) can boost apoptosis and inflammation in several cancers, but its role in OA is unknown.MethodsDifferentially expressed genes in OA were analyzed using the GEO database (GSE169077). RT-qPCR and western blot estimated relative mRNA and protein levels of CA12. Cell viability and apoptosis were estimated by cell counting and flow cytometry assays. Oxidative stress (OxS) was determined by detecting with ROS and MDA levels, as well as CAT and SOD activities. Cytokine levels of IL-6 and TNF-α were detected by ELISA. Parameters associated with apoptosis and extracellular matrix (ECM) were detected by western blot. The m6A modification profile was determined by methylated RNA immunoprecipitation assays.ResultsRelative CA12 and wilms’ tumor 1-associating protein (WTAP) mRNA and protein levels were overexpressed in OA articular cartilages and IL-1β-challenged chondrocytes CHON-001. CA12 silencing impaired IL-1β-induced cell apoptosis, inflammation, OxS, and ECM degradation in chondrocytes. Yet, CA12 overexpression exerted an opposing function. WTAP reinforced the stability of CA12 mRNA depending on the m6A modification. Furthermore, WTAP knockdown weakened cell apoptosis, inflammation, OxS, and ECM degradation in chondrocytes induced by IL-1β, but these changes were impaired after CA12 overexpression. In addition, WTAP knockdown mitigates cartilage degeneration in DMM-induced mouse models.ConclusionIL-1β-induced WTAP enhances CA12 mRNA stability depending on m6A modification, thus promoting chondrocyte apoptosis, inflammatory response, OxS, and ECM degradation, providing evidence to support the possibility of WTAP and CA12 as potential targets for OA treatment.

Diabetic nephropathy (DN) is one of the common microvascular complications in diabetic patients. Marrow mesenchymal stem cells (MSCs) have attracted attention in DN therapy but the underlying mechanism remains unclear. Here, we show that MSC administration alleviates high glucose (HG)-induced human kidney tubular epithelial cell (HK-2 cell) injury and ameliorates renal injury in DN mice. We identify that Smad2/3 is responsible for MSCs-regulated DN progression. The activity of Smad2/3 was predominantly upregulated in HG-induced HK-2 cell and DN mice and suppressed with MSC administration. Activation of Smad2/3 via transforming growth factor-β1 (TGF-β1) administration abrogates the protective effect of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Smad2/3 has been reported to interact with methyltransferase of N6-methyladenosine (m6A) complex and we found a methyltransferase, Wilms' tumor 1-associating protein (WTAP), is involved in MSCs-Smad2/3-regulated DN development. Moreover, WTAP overexpression abrogates the improvement of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Subsequently, α-enolase (ENO1)is the downstream target of WTAP-mediated m6A modification and contributes to the MSCs-mediated regulation. Collectively, these findings reveal a molecular mechanism in DN progression and indicate that Smad2/3/WTAP/ENO1 may present a target for MSCs-mediated DN therapy.

Myocardial infarction (MI) is one of the leading causes of death. Wilms' tumor 1-associating protein (WTAP), one of the components of the m6A methyltransferase complex, has been shown to affect gene expression via regulating mRNA modification. Although WTAP has been implicated in various diseases, its role in MI is unclear. In this study, we found that hypoxia/reoxygenation (H/R) time-dependently increased WTAP expression, which in turn promoted endoplasmic reticulum (ER) stress and apoptosis, in human cardiomyocytes (AC16). H/R effects on ER stress and apoptosis were all blocked by silencing of WTAP, promoted by WTAP overexpression, and ameliorated by administration of ER stress inhibitor, 4-PBA. We then investigated the underlying molecular mechanism and found that WTAP affected m6A methylation of ATF4 mRNA to regulate its expression, and that the inhibitory effects of WTAP on ER stress and apoptosis were ATF4 dependent. Finally, WTAP’s effects on myocardial I/R injury were confirmed in vivo. WTAP promoted myocardial I/R injury through promoting ER stress and cell apoptosis by regulating m6A modification of ATF4 mRNA. These findings highlight the importance of WTAP in I/R injury and provide new insights into therapeutic strategies for MI.

The N6 -methyladenosine (m6 A) modification is one of the most prevalent methylations in eukaryotic messenger RNA (mRNA), and it is essential for the development of many important biological processes such as multiple types of tumors. One of the most important enzymes catalyzing generation of m6 A on mRNA is Wilms' tumor 1-associating protein (WTAP); however, the potential role of WTAP in endometrial cancer (EC) still remains unknown. Here, we investigated WTAP expression level in cancer tissue and paracancerous tissue from an EC patient. Subsequently, WTAP was knocked down by small interfering RNA in EC cell line of Ishikawa and HEC-1A, respectively. Cell proliferation, migration, and invasion were studied. The expression of caveolin-1 (CAV-1) was detected by quantitative polymerase chain reaction (qPCR). The enrichments of m6 A and METTL3 on CAV-1 were detected using RNA immunoprecipitation-qPCR. The activity of nuclear factor-κB (NF-κB) was studied using Western blot. We observed that WTAP was dramatically upregulated in the cancer tissue, and there was an enhancement in cell proliferation, migration, and invasion and adecreasein ECapoptosis in vivo and in vitro, which indicated higher tumor malignancy and worse survival outcome. After WTAP was knocked down in EC cells, CAV-1 was significantly upregulatedand the enrichments of m6 A and METTL3 at 3'-untranslated region (UTR) region of CAV-1 were decreased. Moreover, the activity of NF-κB signaling pathway was inhibited by its regulator CAV-1. Taken together, we concluded that WTAP could methylate 3'-UTR of CAV-1 and downregulate CAV-1 expression to activate NF-κB signaling pathway in EC, which promoted EC progression.

Wilms' tumor 1-associated protein (WTAP) is a key N6-methyladenosine (m6A) methyltransferase that is upregulated in t(8;21) acute myeloid leukemia (AML) under hypoxia inducible factor 1α-mediated transcriptional activation, promoting leukemogenesis through transcriptome-wide m6A modifications. However, the specific substrates and intrinsic regulatory mechanisms of WTAP are not well understood. Here, we provide evidence that PHD finger protein 19 (PHF19) overexpression is regulated by WTAP-mediated m6A modification and promotes cell cycle progression by altering chromatin accessibility. At the same time, high expression of PHF19 and WTAP in t(8;21) AML patients indicates a worse prognosis. Furthermore, inhibition of PHF19 expression significantly suppresses the growth of t(8;21) AML cells in both in vitro and in vivo. Mechanistically, WTAP enhances the stability of PHF19 mRNA by binding to m6A sites in the 3'-untranslated region, thereby upregulating PHF19 expression. Conversely, WTAP suppression reduces m6A modification levels on the PHF19 transcript, leading to increased instability. Knockdown of PHF19 precipitates loss of H3K27 trimethylation and enhanced chromatin accessibility, ultimately resulting in upregulated expression of genes involved in the cell cycle and DNA damage checkpoints. Therefore, WTAP/m6A-dependent PHF19 upregulation accelerates leukemia progression by coordinating m6A modification and histone methylation, establishing its status as a novel therapeutic target for t(8;21) AML.

Wilms’ tumor 1-associating protein (WTAP) is required for N6-methyladenosine (m6A) RNA methylation modifications, which regulate biological processes such as RNA splicing, cell proliferation, cell cycle, and embryonic development. m6A is the predominant form of mRNA modification in eukaryotes. WTAP exerts m6A modification by binding to methyltransferase-like 3 (METTL3) in the nucleus to form the METTL3-methyltransferase-like 14 (METTL14)-WTAP (MMW) complex, a core component of the methyltransferase complex (MTC), and localizing to the nuclear patches. Studies have demonstrated that WTAP plays a critical role in various cancers, both dependent and independent of its role in m6A modification of methyltransferases. Here, we describe the recent findings on the structural features of WTAP, the mechanisms by which WTAP regulates the biological functions, and the molecular mechanisms of its functions in various cancers. By summarizing the latest WTAP research, we expect to provide new directions and insights for oncology research and discover new targets for cancer treatment.

Early-onset preeclampsia (ePE) originates from abnormal implantation and placentation that involves trophoblast invasion, but its pathophysiology is not entirely understood. N6-methyladenosine (m6A) regulators mediate the progression of various cancers. The invasiveness of trophoblast cells is similar to that of tumor cells. However, little is known regarding the potential role of m6A modification in ePE and the underlying mechanism. This study aimed to explore the m6A level in placental tissue samples collected from ePE patients and to investigate whether m6A modification was an essential part of PE pathogenesis. The m6A level in placental tissue samples of 80 PE participants was examined. MeRIP-microarray, RNA-Seq, luciferase reporter assay, and RNA immunoprecipitation chip (RIP) assay were performed. The m6A level in the ePE group was significantly reduced compared with the control group. Wilms' tumor 1-associating protein (WTAP) regulated trophoblast cell migration and invasion. Mechanistically, the high mobility group nucleosomal binding domain 3 (HMGN3) gene was a target gene of WTAP in trophoblast (p < .05). WTAP enhanced the stability of HMGN3 mRNA through binding with its 3'-UTR m6A site(+485A, +522A). HMGN3 was recognized by m6A recognition protein insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), which was inhibited when knocking down WTAP. Both m6A and WTAP levels were downregulated in ePE. The m6A modification mediated by WTAP/IGF2BP1/HMGN3 axis might contribute to abnormal trophoblast invasion. Our work provided a foundation for further exploration of RNA epigenetic regulatory patterns in ePE, and indicated a new treatment strategy for ePE.