Project description:We investigated the relative expression levels of these miRs in a series of meningioma and normal meningeal tissues. The effects of miR-16 and miR-519 on cell growth and transcriptome were assessed in vitro using two human cell lines (Ben-Men-1 and IOMM-Lee). Both miR-16 and miR-519 were significantly downregulated in meningioma compared with normal meningeal tissue. Overexpression of either miR in IOMM-Lee and Ben-Men-1 cells significantly reduced cell growth. The transfection of miR-16 and miR-519 significantly downregulated HuR mRNA, and genes involved in various functions such as pre-replicative complex, mitotic recombination, S phase and M phase of cell cycle, and upregulated genes implicated in cell junction, and positive regulation of cell death. Cell-cycle-related genes associated cluster included HuR mRNA (ELAVL1), and was highly enriched with HuR gene targets.
Project description:Meningiomas are common intracranial tumors in adults. Abnormal miRNA expression plays a role in their pathogenesis. Change in miRNA expression level can be caused by impaired epigenetic regulation of miRNA-encoding genes. We found genomic region covering MIR193B gene as DNA hypermethylated in meningiomas based on analysis of genome-wide methylation (HM450k Illumina arrays). Hypermethylation of MIR193B was as also confirmed by bisulfite pyrosequencing. Both hsa-miR-193b-3p and hsa-miR-193b-5p are downregulated in meningiomas as found with qRT-PCR. Lower expression of hsa-miR-193b-3p and higher MIR193b methylation was observed in WHO GII/GIII as compared to GI meningiomas. 3’UTR of CCND1 mRNA was identified as target of hsa-miR-193b-3p as further validated with luciferase reporter assay in IOMM-Lee meningioma cells. IOMM-Lee cells transfected with hsa-miR-193b-3p mimic showed decreased cyclin D1 level and lower cell viability and proliferation, confirming suppressive nature of this miRNA. Cyclin D1 protein expression (immunoreactivity) was higher in atypical than in benign meningiomas, accordingly to observation of lower hsa-miR-193b-3p level in GII tumors. The commonly observed hypermethylation of MIR193B in meningiomas apparently contributes to downregulation of hsa-miR-193b-3p. Since hsa-miR-193b-3p regulates proliferation of meningioma cells through negative regulation of cyclin D1 expression, it seems to be an important tumor suppressor in meningiomas.
Project description:Meningiomas, one of the most common human brain tumors, are derived from arachnoidal cells associated with brain meninges, usually benign and frequently associated with neurofibromatosis type 2. Here we define a human meningioma-typical miRNA profile and characterize effects of one down-regulated miRNA, miR-200a, on tumor growth. Elevated levels of miR-200a inhibited meningioma cell growth in culture and in a tumor model in vivo. Up-regulation of miR-200a decreased expression of transcription factors, ZEB1 and SIP1, with consequently increased expression of E-cadherin, an adhesion protein associated with cell differentiation. Down-regulation of miR-200a in meningiomas and arachnoidal cells resulted in increased expression of β -catenin and cyclin D1 involved in cell proliferation. miR-200a was found to directly target β -catenin mRNA, thereby inhibiting its translation and blocking β -catenin-Wnt signaling, frequently involved in cancer. A direct correlation was found between down-regulation of miR-200a and up-regulation of β-catenin in human meningioma samples. Thus, miR-200a appears to act as a multi-functional tumor suppressor miRNA in meningiomas through effects on the E-cadherin and β -catenin-Wnt signaling pathways. This reveals a previously unrecognized signaling cascade involved in meningioma tumor development and highlights a novel molecular interaction between miR-200a and Wnt signaling, thereby providing insights into novel therapies for meningiomas. 14 meningioma tumor samples were compared to 3 arachnoidal tissue control samples. Two technical replicates were performed for each sample. Normalization and processing included combining the data from technical replicates. The below table contains quantile-normalized data.
Project description:While microRNAs (miRs) have been extensively studied in the context of malignancy and tumor progression, their functions in regulating T cell activation are less clear. We found reduced levels of miR-15a/16 at 3-18 h post-T cell receptor (TCR) stimulation, suggesting a role in shaping T cell activation. An inducible miR15a/16 transgenic mouse model was developed to determine how elevating miR-15a/16 levels during early stages of activation would affect T cell proliferation and to identify TCR signaling pathways regulated by this miR pair. Doxycyclin (DOX) induced expression of miR-15a/16 from 0-18 h post-TCR stimulation decreased ex vivo proliferation as well as in vivo antigen-specific proliferation. Bioinformatic and proteomic approaches were combined to identify MEK1 as a target of miR-15a/16. MEK1 targeting by miR-15a/16 was confirmed using miR mimics that decreased MEK1 containing the 3’-UTR target nucleotide sequence (UGCUGCUA) but did not decrease MEK1 containing a mutated control sequence (AAAAAAAA). Phosphorylation of downstream signaling molecules ERK1/2 and Elk1 were decreased with DOX-induced miR-15a/16 expression. In addition to MEK1, ERK1 was subsequently found to be targeted by miR-15a/16, with DOX induced miR-15a/16 reducing total ERK1 levels in T cells. These findings show that TCR stimulation reduces miR-15a/16 levels at early stages of T cell activation to facilitate increased MEK1 and ERK1, and this promotes sustained MEK1-ERK1/2-Elk1 signaling required for optimal proliferation.
Project description:Meningiomas, one of the most common human brain tumors, are derived from arachnoidal cells associated with brain meninges, usually benign and frequently associated with neurofibromatosis type 2. Here we define a human meningioma-typical miRNA profile and characterize effects of one down-regulated miRNA, miR-200a, on tumor growth. Elevated levels of miR-200a inhibited meningioma cell growth in culture and in a tumor model in vivo. Up-regulation of miR-200a decreased expression of transcription factors, ZEB1 and SIP1, with consequently increased expression of E-cadherin, an adhesion protein associated with cell differentiation. Down-regulation of miR-200a in meningiomas and arachnoidal cells resulted in increased expression of β -catenin and cyclin D1 involved in cell proliferation. miR-200a was found to directly target β -catenin mRNA, thereby inhibiting its translation and blocking β -catenin-Wnt signaling, frequently involved in cancer. A direct correlation was found between down-regulation of miR-200a and up-regulation of β-catenin in human meningioma samples. Thus, miR-200a appears to act as a multi-functional tumor suppressor miRNA in meningiomas through effects on the E-cadherin and β -catenin-Wnt signaling pathways. This reveals a previously unrecognized signaling cascade involved in meningioma tumor development and highlights a novel molecular interaction between miR-200a and Wnt signaling, thereby providing insights into novel therapies for meningiomas.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192. RNA content was extracted following immunoprecipitation of HuR using a monoclonal antibody (3A2) and the levels of mRNA were compared to an IgG control in order to determine which transcripts were enriched in the HuR ribonucleoprotein complex.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192. RNA content was extracted following immunoprecipitation of HuR using a monoclonal antibody (3A2) and the levels of mRNA were compared to an IgG control in order to determine which transcripts were enriched in the HuR ribonucleoprotein complex.
Project description:The synergism between c-MYC and miR-17-19b, a truncated version of the miR-17-92 cluster, is well documented during tumor initiation. However, little is known about miR-17-19b function in established cancers. Here we investigate the role of miR-17-19b in c-MYC-driven lymphomas by integrating SILAC-based quantitative proteomics, transcriptomics and 3’ UTR analysis upon miR-17-19b overexpression. We identify over one hundred novel miR-17-19b targets, of which 40% are co-regulated by c-MYC. Down-regulation of a new miR-17/20 target Chek2 increases the recruitment of HuR to c-MYC transcripts, resulting in the inhibition of c-MYC translation and thus interfering with in vivo tumor growth. Hence, in established lymphomas, miR-17-19b fine-tunes c-MYC activity through a tight control of its function and expression, ultimately ensuring cancer cell homeostasis. Our data highlight the plasticity of miRNA function, reflecting changes in the mRNA landscape and 3’ UTR shortening at different stages of tumorigenesis.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192.
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192.