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Project description:RNA splicing dysregulation is a hallmark of cancers, promoting the onset and progression of disease. In chronic lymphocytic leukemia (CLL), spliceosome mutations leading to aberrant splicing occur in ~20% of patients. However, the underlying mechanism for splicing defects in spliceosome unmutated CLL cases remains elusive. Through an integrative transcriptomic and proteomic analysis, we discover proteins involved in RNA splicing are post-transcriptionally upregulated in CLL cells, resulting in splicing dysregulation. The abundance of splicing (factors) complexes is an independent risk factor and associated with poor prognosis in CLL. Moreover, increased splicing factor expression is highly correlated with METTL3, an RNA methyltransferase that modifies N6-methyladenosine (m6A) on mRNA. METTL3 is essential for cell growth in vitro and in vivo, and controls splicing factor protein expression in a methyltransferase-dependent manner through m6A modification mediated ribosome recycling and decoding process. Our results uncover a novel regulatory axis of METTL3 for splicing dysregulation in CLL and highlight m6A modification as a major contributor to spliceosome mutation-independent splicing defects that lead to CLL progression.
2023-03-03 | GSE223730 | GEO
Project description:RNA splicing dysregulation is a hallmark of cancers, promoting the onset and progression of disease. In chronic lymphocytic leukemia (CLL), spliceosome mutations leading to aberrant splicing occur in ~20% of patients. However, the underlying mechanism for splicing defects in spliceosome unmutated CLL cases remains elusive. Through an integrative transcriptomic and proteomic analysis, we discover proteins involved in RNA splicing are post-transcriptionally upregulated in CLL cells, resulting in splicing dysregulation. The abundance of splicing (factors) complexes is an independent risk factor and associated with poor prognosis in CLL. Moreover, increased splicing factor expression is highly correlated with METTL3, an RNA methyltransferase that modifies N6-methyladenosine (m6A) on mRNA. METTL3 is essential for cell growth in vitro and in vivo, and controls splicing factor protein expression in a methyltransferase-dependent manner through m6A modification mediated ribosome recycling and decoding process. Our results uncover a novel regulatory axis of METTL3 for splicing dysregulation in CLL and highlight m6A modification as a major contributor to spliceosome mutation-independent splicing defects that lead to CLL progression.
2023-03-03 | GSE223729 | GEO
Project description:RNA splicing dysregulation is a hallmark of cancers, promoting the onset and progression of disease. In chronic lymphocytic leukemia (CLL), spliceosome mutations leading to aberrant splicing occur in ~20% of patients. However, the underlying mechanism for splicing defects in spliceosome unmutated CLL cases remains elusive. Through an integrative transcriptomic and proteomic analysis, we discover proteins involved in RNA splicing are post-transcriptionally upregulated in CLL cells, resulting in splicing dysregulation. The abundance of splicing (factors) complexes is an independent risk factor and associated with poor prognosis in CLL. Moreover, increased splicing factor expression is highly correlated with METTL3, an RNA methyltransferase that modifies N6-methyladenosine (m6A) on mRNA. METTL3 is essential for cell growth in vitro and in vivo, and controls splicing factor protein expression in a methyltransferase-dependent manner through m6A modification mediated ribosome recycling and decoding process. Our results uncover a novel regulatory axis of METTL3 for splicing dysregulation in CLL and highlight m6A modification as a major contributor to spliceosome mutation-independent splicing defects that lead to CLL progression.
2023-03-03 | GSE223728 | GEO
Project description:Background: Osteosarcoma (OS) is the most prevalent bone cancer among children and adolescents, with relatively high mortality rates. RNA N6-methyladenosine (m6A) is the most common human mRNA modification with diverse functions in a variety of biological processes. Previous studies indicated that methyltransferase-like 3 (METTL3), the first methyltransferase to be identified, acted as an oncogene or tumor suppressor in multiple human cancers. However, its functions and underlying mechanisms in OS progression remain unclear; therefore, we explored these processes. Methods: We used real-time quantitative PCR (RT-qPCR) and Western blot assays to explore METTL3 expression in OS tumor tissues and five OS cell lines to assess its clinical significance. To further examine the functional role of METTL3 during OS progression, CCK-8 analyses, transwell assays, and xenograft model studies were conducted after silencing METTL3. Additionally, underlying mechanisms were also explored using RIP-seq and RIP-qPCR approaches. Results: METTL3 was upregulated in OS tumor tissues and cell lines and was associated with a worse prognosis. Moreover, METTL3 silencing suppressed OS cell proliferation, migration, and invasion. Also, in vivo METTL3 oncogenic functions were confirmed in the xenograft model. Comprehensive mechanistic analyses identified long non-coding RNA (lncRNA) DANCR as a potential target of METTL3, as indicated by reduced DANCR levels after METTL3 silencing. Also, lncRNA DANCR knockdown repressed OS cell proliferation, migration, and invasion. Furthermore, both METTL3 and lncRNA DANCR silencing significantly suppressed OS growth and metastasis. Finally, we hypothesized that METTL3 regulated DANCR expression via m6A modification-mediated DANCR mRNA stability. Conclusion: METTL3 contributes to OS progression by increasing DANCR mRNA stability via m6A modification, meaning that METTL3 may be a promising therapeutic target for OS treatment.
| S-EPMC8790117 | biostudies-literature
Project description:N6-methyladenosine (m6A) RNA methylation is the most abundant modification on mRNAs and plays important roles in various biological processes. The formation of m6A is catalyzed by a methyltransferase complex including methyltransferase-like 3 (METTL3) as a key factor. However, the in vivo functions of METTL3 and m6A modification in mammalian development remain unclear. Here, we show that specific inactivation of Mettl3 in mouse nervous system causes severe developmental defects in the brain. Mettl3 conditional knockout (cKO) mice manifest cerebellar hypoplasia caused by drastically enhanced apoptosis of newborn cerebellar granule cells (CGCs) in the external granular layer (EGL). METTL3 depletion-induced loss of m6A modification causes extended RNA half-lives and aberrant splicing events, consequently leading to dysregulation of transcriptome-wide gene expression and premature CGC death. Our findings reveal a critical role of METTL3-mediated m6A in regulating the development of mammalian cerebellum.
| S-EPMC6021109 | biostudies-literature
Project description:The occurrence of distant metastasis is one of the leading causes of death in patients with prostate cancer (PCa). It is confirmed that kinesin protein is associated with a variety of malignancies, and the KIF3 family is related to cancer, but the relationship between KIF3C and prostate cancer is not clear. Our experiments have confirmed that KIF3C is highly expressed in prostate cancer tissues and cell lines. Further, functional tests have proven that KIF3C can promote the growth migration and invasion of PCa. We used Starbase 3.0 to discover that methyltransferase like 3 (METTL3) interacts with KIF3C. Our hypothesis and experiments concluded that METTL3 induced m6A modification on KIF3C, promoting the stabilization of KIF3C-mRNA by IGF2 binding protein 1 (IGF2BP1). The prediction that miR-320d inhibits KIF3C expression by targeting METTL3 using the miRmap website, was later confirmed experimentally. Further, a recovery experiment was used to confirm that miR-320d inhibited the progression of prostate cancer. KIF3C was overexpressed in prostate cancer, promoting its growth migration and invasion was induced by miR-320d/METTL3 in an m6A dependent process.
| S-EPMC8507285 | biostudies-literature
Project description:Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of lymphoma, whose treatment still has a major challenge of achieving a satisfactory curative effect. The underlying mechanisms also have not been fully illustrated. N 6-Methyladenosine (m6A) has been identified as the most prevalent internal modification of mRNAs present in eukaryotes, which is involved in the pathogenesis of cancers. It remains unclear how m6A mRNA methylation is functionally linked to the pathogenesis of DLBCL. In this study, we sought to explore the roles of METTL3 on DLBCL development. The results showed that m6A level for RNA methylation and the expression level of METTL3 were upregulated in DLBCL tissues and cell lines. Functionally, downregulated METTL3 expression in DLBCL cells inhibited the cell proliferation ability. Further mechanism analysis indicated that METTL3 knockdown abates the m6A methylation and total mRNA level of pigment epithelium-derived factor (PEDF). However, Wnt/β-catenin signaling was not thus activated. Overexpressed PEDF abrogates the inhibition of cell proliferation in DLBCL cells that is caused by METTL3 silence. In summary, the above-mentioned results demonstrated that the METTL3 promotes DLBCL progression by regulating the m6A level of PEDF.
| S-EPMC7481464 | biostudies-literature
Project description:BackgroundColorectal carcinoma (CRC) is the third most common cancer and second most common cause of cancer-related deaths worldwide. Ribonucleic acid (RNA) N6-methyladnosine (m6A) and methyltransferase-like 3 (METTL3) play key roles in cancer progression. However, the roles of m6A and METTL3 in CRC progression require further clarification.MethodsAdenoma and CRC samples were examined to detect m6A and METTL3 levels, and tissue microarrays were performed to evaluate the association of m6A and METTL3 levels with the survival of patients with CRC. The biological functions of METTL3 were investigated through cell counting kit-8, wound healing, and transwell assays. M6A epitranscriptomic microarray, methylated RNA immunoprecipitation-qPCR, RNA stability, luciferase reporter, and RNA immunoprecipitation assays were performed to explore the mechanism of METTL3 in CRC progression.ResultsM6A and METTL3 levels were substantially elevated in CRC tissues, and patients with CRC with a high m6A or METTL3 levels exhibited shorter overall survival. METTL3 knockdown substantially inhibited the proliferation, migration, and invasion of CRC cells. An m6A epitranscriptomic microarray revealed that the cell polarity regulator Crumbs3 (CRB3) was the downstream target of METTL3. METTL3 knockdown substantially reduced the m6A level of CRB3, and inhibited the degradation of CRB3 mRNA to increase CRB3 expression. Luciferase reporter assays also showed that the transcriptional level of wild-type CRB3 significantly increased after METTL3 knockdown but not its level of variation. Knockdown of YT521-B homology domain-containing family protein 2 (YTHDF2) substantially increased CRB3 expression. RNA immunoprecipitation assays also verified the direct interaction between the YTHDF2 and CRB3 mRNA, and this direct interaction was impaired after METTL3 inhibition. In addition, CRB3 knockdown significantly promoted the proliferation, migration, and invasion of CRC cells. Mechanistically, METTL3 knockdown activated the Hippo pathway and reduced nuclear localization of Yes1-associated transcriptional regulator, and the effects were reversed by CRB3 knockdown.ConclusionsM6A and METTL3 levels were substantially elevated in CRC tissues relative to normal tissues. Patients with CRC with high m6A or METTL3 levels exhibited shorter overall survival, and METTL3 promoted CRC progression. Mechanistically, METTL3 regulated the progression of CRC by regulating the m6A-CRB3-Hippo pathway.
| S-EPMC8744223 | biostudies-literature
Project description:Objective:This study aims to uncover the progression of thyroid carcinoma influenced by the m6A methyltransferase METTL3 through regulating m6A methylation on TCF1 mRNA and the activated Wnt pathway. Methods:Thyroid carcinoma tissues and paracancerous ones were collected for detecting levels of METTL3 and TCF1. Potential correlation between levels of METTL3 and TCF1 was analyzed by Pearson analysis. Survival of thyroid carcinoma patients influenced by METTL3 level was assessed by Kaplan-Meier method. Regulatory effect of METTL3 on migratory ability in TPC-1 cells was examined by wound healing assay. The interaction between METTL3 with TCF1 and IGF2BP2 was verified by RNA-Binding Protein Immunoprecipitation (RIP) assay. Meanwhile, the activity of the Wnt pathway was reflected by TOP/FOP-Flash. At last, rescue experiments were conducted to clarify the involvement of TCF1 in phenotype changes of thyroid carcinoma cells that were regulated by METTL3. Results:METTL3 and TCF1 were upregulated in thyroid carcinoma. Similarly, METTL3 was highly expressed in thyroid carcinoma cells as well. Kaplan-Meier method uncovered poor prognosis in thyroid carcinoma patients expressing a high level of METTL3. Silence of METTL3 inhibited migratory ability and Wnt activity in TPC-1 cells. RIP assay confirmed the interaction between TCF1 and METTL3 or IGF2BP2. Moreover, METTL3 positively regulated the enrichment abundance of TCF1 in anti-IGF2BP2. Rescue experiments demonstrated that TCF1 was responsible for METTL3-regulated thyroid carcinoma progression via the m6A methylation. Conclusion:Upregulated m6A methyltransferase METTL3 promotes the progression of thyroid carcinoma through m6A methylation on TCF1.
| S-EPMC7044742 | biostudies-literature
Project description:Nuclear stress bodies (nSBs) are nuclear membraneless organelles formed around stress-inducible HSATIII architectural long noncoding RNAs (lncRNAs). nSBs repress splicing of hundreds of introns during thermal stress recovery, which are partly regulated by CLK1 kinase phosphorylation of temperature-dependent Ser/Arg-rich splicing factors (SRSFs). Here we report a distinct mechanism for this splicing repression through protein sequestration by nSBs. Comprehensive identification of RNA-binding proteins revealed HSATIII association with proteins related to N6-methyladenosine (m6A) RNA modification. 11% of the first adenosine in the repetitive HSATIII sequence were m6A-modified. nSBs sequester the m6A writer complex to methylate HSATIII, leading to subsequent sequestration of the nuclear m6A reader, YTHDC1. Sequestration of these factors from the nucleoplasm represses m6A modification of pre-mRNAs, leading to repression of m6A-dependent splicing during stress recovery phase. Thus, nSBs serve as a common platform for regulation of temperature-dependent splicing through dual mechanisms employing two distinct ribonucleoprotein modules with partially m6A-modified architectural lncRNAs.
| S-SCDT-EMBOJ-2021-107976 | biostudies-other