Project description:miR-92 enhances c-Myc induced apoptosis. In the R26MER/MER mouse embryonic fibroblasts (MEFs), a switchable variant of Myc, MycERT2, was knocked into the genomic region downstream of the constitutive Rosa26 promoter, allowing acute activation of c-Myc by 4-OHT-induced nuclear translocation. This in vitro system nicely recapitulates c-Myc-induced apoptosis, as activated MycERT2 induces strong p53-dependent apoptosis in response to serum starvation. Enforced miR-92 expression in three independent R26MER/MER MEF lines significantly enhanced Myc-induced apoptosis. We used microarrays to investigate the molecular mechanism underlying miR-92 functions. Three independent R26MER/MER MEF lines were infected by MSCV vector alone or by MSCV vector encoding miR-92. These MEFs were serum starved and 4-OHT treated to trigger strong Myc-induced apoptosis.
Project description:miR-92 enhances c-Myc induced apoptosis. In the R26MER/MER mouse embryonic fibroblasts (MEFs), a switchable variant of Myc, MycERT2, was knocked into the genomic region downstream of the constitutive Rosa26 promoter, allowing acute activation of c-Myc by 4-OHT-induced nuclear translocation. This in vitro system nicely recapitulates c-Myc-induced apoptosis, as activated MycERT2 induces strong p53-dependent apoptosis in response to serum starvation. Enforced miR-92 expression in three independent R26MER/MER MEF lines significantly enhanced Myc-induced apoptosis. We used microarrays to investigate the molecular mechanism underlying miR-92 functions.
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:miR-17-92 mediates the MYC oncogene addiction in a conditional mouse lymphoma model. To identify targets of miR-17-92 in this model, miR-17-92 was expressed in the conditional lymphoma cell lines using MSCV-puro. Both control and miR-17-92-expressing conditional lymphoma cell lines were treated with doxycycline (DOX) (20ng/ml) for 48 hours to shut off MYC expression.
Project description:Analysis of JNK-dependent fibroblast-derived soluble factors at gene expression level. The hypothesis tested in the present study was that loss of c-Jun N-terminal kinases 1 and 2, JNK1 and JNK2, in MEFs causes a strong alteration of the gene expression program coding for soluble factors, which promote an efficient keratinocyte differentiation. Results provide important information of the repertoire of fibroblast transcripts encoding secreted proteins, which is severely disarranged upon loss of JNK activity under the in vitro co-culture conditions applied. In vitro transwell co-culture experiments were performed using jnk1-/-jnk2-/- or wildtype immortalized mouse embryonic fibroblasts (MEFs) and differentiating primary normal human epidermal keratinocytes (NHEK) over a time course of 6 days. Every second day, fibroblast-loaded inserts were changed resulting in 3 triads (triads 1, 2, and 3). Total RNA was obtained from jnk1-/-jnk2-/- and wildtype immortalized mouse embryonic fibroblasts (MEFs) prior to co-cultivation (day 0) and of each triad 1, 2, or 3.
Project description:The Tgf-b signaling pathway plays an important role in both embryonic development and epithelial to mesenchymal transition (EMT), but the influence of this pathway and its relationship with EMT in fibroblast reprogramming is not defined. Using Affymetrix mouse genome array and mouse embryonic fibroblast cells (MEFs), we analyzed the expression profiles of Tgf-b1 and one of its important mediators in EMT, Snail, regulated genes at Day 10 during the process of reprogramming. A total of 535 genes were differentially expressed (2-fold change) in cells activated by Tgf-b1 and 970 genes were differentially expressed in cells over-expressing Snail. Among them, 170 genes were shared in both categories. The differentially expressed genes involve in many biological processes, including Tgf-b signaling pathway, cell communication, ECM-receptor interaction, cell adhesion, focal adhersion, and Hedgehog signaling pathway
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.