Project description:Medulloblastoma is the most common malignant pediatric brain tumor, and mechanisms underlying its development are poorly understood. We identified recurrent amplification of the miR-17/92 polycistron proto-oncogene in 6% of pediatric medulloblastomas by high-resolution single-nucleotide polymorphism genotyping arrays and subsequent interphase fluorescence in situ hybridization on a human medulloblastoma tissue microarray. Profiling the expression of 427 mature microRNAs (miRNA) in a series of 90 primary human medulloblastomas revealed that components of the miR-17/92 polycistron are the most highly up-regulated miRNAs in medulloblastoma. Expression of miR-17/92 was highest in the subgroup of medulloblastomas associated with activation of the sonic hedgehog (Shh) signaling pathway compared with other subgroups of medulloblastoma. Medulloblastomas in which miR-17/92 was up-regulated also had elevated levels of MYC/MYCN expression. Consistent with its regulation by Shh, we observed that Shh treatment of primary cerebellar granule neuron precursors (CGNP), proposed cells of origin for the Shh-associated medulloblastomas, resulted in increased miR-17/92 expression. In CGNPs, the Shh effector N-myc, but not Gli1, induced miR-17/92 expression. Ectopic miR-17/92 expression in CGNPs synergized with exogenous Shh to increase proliferation and also enabled them to proliferate in the absence of Shh. We conclude that miR-17/92 is a positive effector of Shh-mediated proliferation and that aberrant expression/amplification of this miR confers a growth advantage to medulloblastomas.
Project description:During acute viral infections, effector CD8+ T cells differentiate into memory precursors or short-lived terminal effectors. miR-17-92a over-expression skews CD8+ effector cells to the terminal differentiation. We used microarray to identify the genes that are differentially expressed caused by miR-17-92a over-expression. CD8+ T cells from P14 TCR transgenic mice were infected with miR-17-92a-MSCV-IRES-Thy1.1 vector and transfer to C57BL6 recipients. Chimeras were infected with LCMV Armstrong. Thy1.1+ miR-17-92a-MSCV-IRES-Thy1.1 transduced P14 cells and Thy1.1- non-transduced P14 cells were sorted by FACS. RNA was extracted from samples, labeled, and hybridized to Affymetrix microarrays.
Project description:Medulloblastoma is the most common malignant pediatric brain tumor, and mechanisms underlying its development are poorly understood. We identified recurrent amplification of the miR-17/92 polycistron proto-oncogene in 6% of pediatric medulloblastomas by high-resolution single-nucleotide polymorphism genotyping arrays and subsequent interphase fluorescence in situ hybridization on a human medulloblastoma tissue microarray. Profiling the expression of 427 mature microRNAs (miRNA) in a series of 90 primary human medulloblastomas revealed that components of the miR-17/92 polycistron are the most highly up-regulated miRNAs in medulloblastoma. Expression of miR-17/92 was highest in the subgroup of medulloblastomas associated with activation of the sonic hedgehog (Shh) signaling pathway compared with other subgroups of medulloblastoma. Medulloblastomas in which miR-17/92 was up-regulated also had elevated levels of MYC/MYCN expression. Consistent with its regulation by Shh, we observed that Shh treatment of primary cerebellar granule neuron precursors (CGNP), proposed cells of origin for the Shh-associated medulloblastomas, resulted in increased miR-17/92 expression. In CGNPs, the Shh effector N-myc, but not Gli1, induced miR-17/92 expression. Ectopic miR-17/92 expression in CGNPs synergized with exogenous Shh to increase proliferation and also enabled them to proliferate in the absence of Shh. We conclude that miR-17/92 is a positive effector of Shh-mediated proliferation and that aberrant expression/amplification of this miR confers a growth advantage to medulloblastomas. A total of 90 primary medulloblastoma specimens were profiled by Affymetrix exon array and gene-level analysis was performed.
Project description:During acute viral infections, effector CD8+ T cells differentiate into memory precursors or short-lived terminal effectors. miR-17-92a over-expression skews CD8+ effector cells to the terminal differentiation. We used microarray to identify the genes that are differentially expressed caused by miR-17-92a over-expression.
Project description:Adult beta cells in the pancreas are the sole source of insulin in our body. Beta cell loss or increased demand for insulin, impose metabolic challenges because adult beta cells are generally quiescent and infrequently re-enter the cell division cycle. miR-17-92/106b is a family of proto-oncogene microRNAs, that regulate proliferation in normal tissues and in cancer. Here, we employ mouse genetics to demonstrate a critical role for miR-17-92/106b in glucose homeostasis and in controlling insulin secretion. Mass spectrometry analysis was performed on miR-17-92LoxP/LoxP;106-25-/- MEF lysate, without or with CRE-Adenovirus. miR-17-92LoxP/LoxP;106-25+/+ MEFs with GFP-Adenovirus served as controls. We demonstrate that miR-17-92/106b regulate the adult beta cell mitotic checkpoint and that miR-17-92/106b deficiency results in reduction in beta cell mass in-vivo. Furthermore, protein kinase A (PKA) is a new relevant molecular pathway downstream of miR-17-92/106b in control of adult beta cell division and glucose homeostasis. Therefore, contributes to the understanding of proto-oncogene miRNAs in the normal, untransformed endocrine pancreas, and illustrates new genetic means for regulation of beta cell mitosis and function by non-coding RNAs.
Project description:MicroRNAs (miRNAs) are conserved small non-coding RNAs that regulate gene expression at the posttranscriptional level by pairing to the 3’ UTR of other genes. miR-17-92 is a key regulator of lymphocyte biology, controlling e.g. cell proliferation, survival as well as differentiation and function of different T cell subsets. miR-17-92 is amplified in human lymphomas and other malignancies and is also involved in additional disorders including immune, cardiovascular and neurodegenerative diseases as well as in aging. Given the importance of miR-17-92 in such a variety of diseases we aim at exploiting it as a therapeutic target. miRNAs can be inhibited through the administration of nucleotide-based inhibitors. Major disadvantages are their transient effect, instability and poor in vivo delivery. In contrast, small molecules permeate cells easily, are intracellularly stable and large libraries are available for high-throughput screening. We screened 60’000 compounds using a luciferase reporter assay and identified small molecules which modulate miR-17 reporter activity. Treatment of mouse naïve CD4 or CD8 T cells with one of the hit compounds resulted in similar phenotypes as in miR-17-92 deficient mice (different target derepression and reduced in vitro T cell differentiation). Screening of 172 chemically related compounds identified 2 analogs with improved potency. Treatment of primary human CD4 or CD8 cells as well as different tumor cell lines overexpressing the miR-17-92 cluster resulted in reduced proliferation and activation and increased cell death.
Project description:MicroRNAs (miRNAs) are conserved small non-coding RNAs that regulate gene expression at the posttranscriptional level by pairing to the 3’ UTR of other genes. miR-17-92 is a key regulator of lymphocyte biology, controlling e.g. cell proliferation, survival as well as differentiation and function of different T cell subsets. miR-17-92 is amplified in human lymphomas and other malignancies and is also involved in additional disorders including immune, cardiovascular and neurodegenerative diseases as well as in aging. Given the importance of miR-17-92 in such a variety of diseases we aim at exploiting it as a therapeutic target. miRNAs can be inhibited through the administration of nucleotide-based inhibitors. Major disadvantages are their transient effect, instability and poor in vivo delivery. In contrast, small molecules permeate cells easily, are intracellularly stable and large libraries are available for high-throughput screening. We screened 60’000 compounds using a luciferase reporter assay and identified small molecules which modulate miR-17 reporter activity. Treatment of mouse naïve CD4 or CD8 T cells with one of the hit compounds resulted in similar phenotypes as in miR-17-92 deficient mice (different target derepression and reduced in vitro T cell differentiation). Screening of 172 chemically related compounds identified 2 analogs with improved potency. Treatment of primary human CD4 or CD8 cells as well as different tumor cell lines overexpressing the miR-17-92 cluster resulted in reduced proliferation and activation and increased cell death.
2026-05-21 | GSE203620 | GEO
Project description:Temporal expression of miR-17-92a regulates effector and memory CD8+ T cell differentiation
Project description:Neonates often generate incomplete immunity against intracellular pathogens, although the mechanism of this defect is poorly understood. An important question is whether the impaired development of memory CD8+ T cells in neonates is due to an immature priming environment or lymphocyte-intrinsic defects. Here we show that neonatal and adult CD8+ T cells adopted different fates when responding to equal amounts of stimulation in the same host. While adult CD8+ T cells differentiated into a heterogeneous pool of effector and memory cells, neonatal CD8+ T cells preferentially gave rise to short-lived effector cells and exhibited a distinct gene expression profile. Surprisingly, impaired neonatal memory formation was not due to a lack of responsiveness, but instead because neonatal CD8+ T cells expanded more rapidly than adult cells and quickly became terminally differentiated. Collectively, these findings demonstrate that neonatal CD8+ T cells exhibit an imbalance in effector and memory CD8+ T cell differentiation, which impairs the formation of memory CD8+ T cells in early life mRNA profiles of effector CD8+ T cells from neonatal and adult mice
Project description:A network of gene regulatory factors such as transcription factors and microRNAs establish and maintain the gene expression pattern during hematopoiesis. In this network transcription factors regulate each other and are involved in regulatory loops with microRNAs.The microRNA cluster miR-17-92 is located within the MIR17HG gene and encodes for six mature microRNAs. It is important for hematopoietic differentiation and plays a central role in malignant disease. However, the transcription factors downstream of miR-17-92 are largely elusive and the transcriptional regulation of miR-17-92 is not fully understood. Here we show that miR-17-92 forms a regulatory loop with the transcription factor TAL1. The miR-17-92 cluster inhibits expression of TAL1 and indirectly leads to decreased stability of the TAL1 transcriptional complex. We found that TAL1 and its heterodimerization partner E47 regulate miR-17-92 transcriptionally. Furthermore, miR-17-92 negatively influences erythroid differentiation, a process that depends on gene activation by the TAL1 complex. Our data give example of how transcription factor activity is fine-tuned during normal hematopoiesis. We postulate that disturbance of the regulatory loop between TAL1 and the miR-17-92 cluster could be an important step in cancer development and progression.