Project description:To investigate differences in gene expression after overexpression miR-218 in U251MG 2 Samples, one transduced with miR-control and one with miR-218.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Receptor tyrosine kinase pathway signalings plays a central role in the growth and progression of glioblastoma, a highly aggressive group of brain tumors. We recently reported that miR-218 repression, an essentially uniform feature of human GBM, directly promotes RTK hyperactivation by increasing the expression of key positive signaling effectors, including EGFR, PLCr1, PIK3CA and ARAF. However, enhanced RTK signaling is known to activate compensatory inhibitory feedback mechanisms in both normal and cancer cells. We demonstrate here that miR-218 repression in GBM cells also increases the abundance of additional up stream and downstream signaling mediators, including PDGFRa, RSK2, and S6K1, which collectively funciton to alleviate inhibitory RTK feedback regulation. In turn, RTK signaling suppresses miR-218 expression via STAT3, which binds to the miR-218 locus, along with BCLAF1, to repress its expression. These data identify novel interacting feedback loops by which miR-218 repression promotes increased RTK signaling in high-grade gliomas.
Project description:The assembly of the mammalian brain is orchestrated by temporally coordinated waves of gene expression. Post-transcriptional regulation of gene expression by microRNAs (miRNAs) is a key aspect of this program. Indeed, deletion of neuron-enriched miRNAs induces strong developmental phenotypes, and miRNA levels are altered in patients with neurodevelopmental disorders. However, the mechanisms used by miRNAs to instruct brain development remain largely unexplored. Here, we identified miR-218 as a critical regulator of hippocampal assembly. MiR-218 is highly expressed in the hippocampus and enriched in both excitatory principal neurons (PNs) and GABAergic inhibitory interneurons (INs). Early life inhibition of miR-218 results in an adult brain with a predisposition to seizures. Changes in gene expression in the absence of miR-218 suggest that network assembly is impaired. Indeed, we find that miR-218 inhibition results in the disruption of early depolarizing GABAergic signaling, structural defects in dendritic spines, and altered intrinsic membrane excitability. Conditional knockout of miR-218 in INs, but not PNs, is sufficient to recapitulate long-term instability. Finally, de-repressing Kif21b and Syt13, two miR-218 targets, phenocopies the effects on early synchronous network activity induced by miR-218 inhibition. Taken together, the data suggest that miR-218 orchestrates formative events in PNs and INs to produce stable networks.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
Project description:Motor-neuron specific microRNA-218 (miR-218) was recently put in the spotlight because of its striking roles in mouse development. However, miR-218 relevance to human motor neuron disease was not yet explored. Here, we demonstrate by neuropathology that miR-218 is abundant in healthy human motor neurons. However, in amyotrophic lateral sclerosis (ALS) motor neurons miR-218 is downregulated and its mRNA targets are reciprocally upregulated (de-repressed). We further identify the potassium channel Kv10.1 as a new miR-218 direct target that controls neuronal activity. In addition, we screened thousands of ALS genomes and identified six rare variants in the human miR-218-2 sequence. Intriguingly, miR-218 gene variants fail to regulate neuron activity, suggesting the importance of this small endogenous RNA for neuronal robustness. The underlying mechanisms involve inhibition of miR-218 biogenesis and reduced processing by DICER. Therefore, miR-218 activity uncovers a previously unappreciated facet of motor neuron specificity that may be particularly susceptible to failure in human ALS, contributes to a view of ALS as a disease with a prominent RNA component and suggests that miR-218 is a potential therapeutic target for motor neuron disease.