MicroRNAs (miRNAs) are short noncoding RNA molecules regulating the expression of mRNAs. Target identification of miRNAs is computationally difficult due to the relatively low homology between miRNAs and their targets. We present here an experimental approach to target identification where the cartilage-specific miR-140 was overexpressed and silenced in cells it is normally expressed in separate experiments. Expression of mRNAs was profiled in both experiments and the intersection of mRNAs repressed by miR-140 overexpression and derepressed by silencing of miR-140 was identified. The intersection contained only 49 genes, although both treatments affected the accumulation of hundreds of mRNAs. These 49 genes showed a very strong enrichment for the miR-140 seed sequence implying that the approach is efficient and specific. 21 of these 49 genes were predicted to be direct targets based on the presence of the seed sequence. Interestingly, none of these were predicted by the published target prediction methods we used. One of the potential target mRNAs, Cxcl12, was experimentally validated by Northern blot analysis and a luciferase reporter assay.
Experimental identification of microRNA-140 targets by silencing and overexpressing miR-140.
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View SamplesThe transcription factor Evi1 is essential for the formation and maintenance of hematopoietic stem cells, and induces clonal dominance with malignant progression upon constitutive activation by chromosomal rearrangements or transgene integration events. To understand the immediate and adaptive response of primary murine hematopoietic cells to the transcriptional upregulation of Evi1, we developed an inducible lentiviral vector system with a robust expression switch. We found that Evi1 delays differentiation and promotes survival in myeloid culture conditions, orchestrating a battery of genes involved in stemness (Aldh1a1, Ly6a [Sca1], Abca1, Epcam, among others). Importantly, Evi1 suppresses Cyclins and Cyclin-dependent kinases (Cdk), while it upregulates Cdk inhibitors, inducing quiescence in various proliferation-inducing cytokine conditions and operating in a strictly dose-dependent manner. Hematopoietic cells with persisting Evi1-induction tend to adopt a relatively low expression level. We thus classify Evi1 as a dormancy-inducing oncogene, likely requiring epigenetic and genetic compensation for cell expansion and malignant progression.
Activation of Evi1 inhibits cell cycle progression and differentiation of hematopoietic progenitor cells.
Specimen part
View SamplesThe specific contribution of the two TNF-receptors Tnfr1 and Tnfr2 to TNF-induced inflammation in the glomerulus is unknown. In mice, TNF exposure induces glomerular expression of inflammatory mediators like adhesion molecules and chemokines in vivo, and glomerular accumulation of leukocytes.
Distinct contributions of TNF receptor 1 and 2 to TNF-induced glomerular inflammation in mice.
Specimen part, Treatment
View SamplesThe cellular heterogeneity of the brain confounds efforts to elucidate the biological properties of distinct neuronal populations.
A translational profiling approach for the molecular characterization of CNS cell types.
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View SamplesThe cellular heterogeneity of the brain confounds efforts to elucidate the biological properties of distinct neuronal populations.
A translational profiling approach for the molecular characterization of CNS cell types.
No sample metadata fields
View SamplesThe cellular heterogeneity of the brain confounds efforts to elucidate the biological properties of distinct neuronal populations.
A translational profiling approach for the molecular characterization of CNS cell types.
No sample metadata fields
View SamplesAlpha-synuclein is an abundant protein implicated in synaptic function and plasticity, but the molecular mechanism of its action is not understood. Missense mutations and gene duplication/triplication events result in Parkinson's disease, a neurodegenerative disorder of old age with impaired movement and emotion control. Here, we systematically investigated the striatal as well as the cerebellar transcriptome profile of alpha-synuclein-deficient mice via a genome-wide microarray survey in order to gain hypothesis-free molecular insights into the physiological function of alpha-synuclein. A genotype-dependent, specific and strong downregulation of forkhead box P1 (Foxp1) transcript levels was observed in all brain regions from postnatal age until old age and could be validated by qPCR. In view of the co-localization and heterodimer formation of FOXP1 with FOXP2, a transcription factor with a well established role for vocalization, and the reported regulation of both alpha-synuclein and FOXP2 expression during avian song learning, we performed a detailed assessment of mouse movements and vocalizations in the postnatal period. While there was no difference in isolation-induced behavioral activity in these animals, the alpha-synuclein-deficient mice exhibited an increased production of isolation-induced ultrasonic vocalizations (USVs). This phenotype might also reflect the reduced expression of the anxiety-related GABA-A receptor subunit gamma 2 (Gabrg2) we observed. Taken together, we identified an early behavioral consequence of alpha-synuclein deficiency and accompanying molecular changes, which supports the notion that the neural connectivity of sound or emotion control systems is affected.
Alpha-synuclein deficiency affects brain Foxp1 expression and ultrasonic vocalization.
Age, Specimen part
View SamplesUniparental parthenotes are considered an unwanted byproduct of in vitro fertilization. In utero parthenote development is severely compromised by defective organogenesis and in particular by defective cardiogenesis. Although developmentally compromised, apparently pluripotent stem cells can be derived from parthenogenetic blastocysts. Here we hypothesized that nonembryonic parthenogenetic stem cells (PSCs) can be directed toward the cardiac lineage and applied to tissue-engineered heart repair. We first confirmed similar fundamental properties in murine PSCs and embryonic stem cells (ESCs), despite notable differences in genetic (allelic variability) and epigenetic (differential imprinting) characteristics. Haploidentity of major histocompatibility complexes (MHCs) in PSCs is particularly attractive for allogeneic cell-based therapies. Accordingly, we confirmed acceptance of PSCs in MHC-matched allotransplantation. Cardiomyocyte derivation from PSCs and ESCs was equally effective. The use of cardiomyocyte-restricted GFP enabled cell sorting and documentation of advanced structural and functional maturation in vitro and in vivo. This included seamless electrical integration of PSC-derived cardiomyocytes into recipient myocardium. Finally, we enriched cardiomyocytes to facilitate engineering of force-generating myocardium and demonstrated the utility of this technique in enhancing regional myocardial function after myocardial infarction. Collectively, our data demonstrate pluripotency, with unrestricted cardiogenicity in PSCs, and introduce this unique cell type as an attractive source for tissue-engineered heart repair.
Parthenogenetic stem cells for tissue-engineered heart repair.
Specimen part
View SamplesNotch signaling regulates a variety of developmental cell fates decisions in a cell-context dependent manner. Although Notch signaling directly regulates transcription via the RBP-J/CSL DNA binding protein, little is known about the genes in the respective tissues that are directly activated by Notch.
Activated Notch1 target genes during embryonic cell differentiation depend on the cellular context and include lineage determinants and inhibitors.
Specimen part
View SamplesJoMa1 cells are pluripotent precursor cells, derived from the neural crest of mice transgenic for tamoxifen-inducible c-Myc. Following transfection with a cDNA encoding for MYCN, cells become immortlized even in the absence of tamoxifen.
MYCN and ALKF1174L are sufficient to drive neuroblastoma development from neural crest progenitor cells.
Specimen part, Cell line
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