Project description:As recently reported by our group, we performed miRNA and gene expression profiling of CD34+ hematopoietic stem/progenitor cells (HSPCs) isolated from 42 PMF patient samples compared with 31 healthy controls. Integrative analysis of these profiles by means of Ingenuity Pathway Analysis (IPA) allowed the identification of several aberrantly regulated miRNA-mRNA target pairs organized in interaction networks. In particular, our results highlighted the up-regulation of miR-494-3p in CD34+ cells from PMF patients (Norfo R et al, Blood, 2014). Interestingly, among the most upregulated miRNAs, miR-494-3p emerges as being associated to the highest number of downregulated target mRNAs. In order to understand the biological role of miR-494-3p during the hematopoietic commitment and differentiation, we overexpressed this miRNA in cord blood (CB) derived-CD34+ cells. Cells were electroporated with either miR-494-3p miRNA mimic (mimic miR-494) or a negative control mimic (mimic Neg CTR). qRT-PCR confirmed miR-494-3p overexpression 24h and 4 days after transfection (RQ ± SEM, 512.60 ± 137.37, p<.01, and 20.63 ± 3.03, p<.01, respectively). Immunophenotypic analysis of CD41 and CD42b megakaryocyte (MK) lineage differentiation markers, performed on serum-free megakaryocytic ultilineage culture at day 3, 5, 8, 10 and 12, demonstrated that miR-494-3p overexpression induces a significant increase in the MK fraction compared to control samples. Accordingly, morphological analysis of May-Grünwald-Giemsa stained cytospins revealed an expansion of megakaryocytic lineage in samples overexpressing miR-494-3p. These data were further confirmed by collagen-based clonogenic assays which showed a significant increase in the percentage of megakaryocytic colonies in miR-494-3p overexpressing samples compared with controls. In order to better characterize the molecular mechanisms underlying the effects of miR-494-3p on HSPCs differentiation, we performed gene expression analysis of miR-494-3p overexpressing cells 24 hours after the last nucleofection.
Project description:High expression of miR-494-3p have been associated with poor prognosis in non-small cell lung cancer (NSCLC). However, the role of miR-494-3p in the development and progression of NSCLC remains elusive. In this study, we found that miR-494-3p was overexpressed in both lung adenocarcinoma and lung squamous cell carcinoma in the Clinical Proteomic Tumor Analysis Consortium and Cancer Genome Atlas databases. A bioinformatic analysis revealed that representative pathways associated with cancer metastasis were enriched in the genes positively correlated with miR-494-3p expression levels, suggesting the potential involvement of miR-494-3p in aggressive properties of NSCLC. To identify potential targets of miR-494-3p, we explored genes inversely correlated with miR-494-3p in the mRNA expression datasets of NSCLC cell lines obtained from the Cancer Dependency Map. Integration of RNA sequencing analysis of NSCLC cells with miR-494-3p inhibition and a bioinformatic search of miRNA target prediction algorithms resulted in identification of SET/I2PP2A as a direct target of miR-494-3p. We found that suppression of SET/I2PP2A by miR-494-3p promoted cell migration and invasion, but not cell viability, in NSCLC cells, indicative of miR-494-3p and its downstream molecules as potential therapeutic targets in NSCLC with aggressive phenotypes.
Project description:The transcription factor c-Myb plays a key role in human primary CD34+ hematopoietic progenitor cells (HPCs) lineage choice, by enhancing erythropoiesis at the expense of megakaryopoiesis. We previously demonstrated that c-Myb affects erythroid versus megakaryocyte lineage decision in part by transactivating KLF1 and LMO2 expression. To further unravel the molecular mechanisms through which c-myb affects lineage fate decision, we profiled the miRNA and mRNA changes in myb-silenced CD34+ HPCs. The integrative analysis of miRNA/mRNA expression changes upon c-myb silencing in human CD34+ HPCs highlighted a set of 19 miRNA with 150 anticorrelated putative target mRNAs. Among the miRNAs downregulated in myb-silenced progenitors with the highest number of predicted target mRNAs, we selected hsa-miR-486-3p based on the in vitro effects of its overexpression on HPCs commitment. Indeed, morphological and flow cytometric analyses after liquid culture showed that hsa-miR-486-3p overexpression in HPCs enhanced erythroid and granulocyte differentiation while restraining megakaryocyte and macrophage differentiation. Moreover, collagen-based clonogenic assay demonstrated a strong impairement megakaryocyte commitment upon hsa-miR-486-3p overexpression in CD34+ cells. Moreover, in order to identify the mRNA target through which hsa-miR-486-3p affects lineage fate decision, we profiled the mRNA changes in mimic transfected CD34+ HPC by means of Affymetrix GeneAtlas U219 strip array. Gene expression profiling of hsa-miR-486-3p overexpressing CD34+ cells enabled us to identify a set of 8 genes downregulated and computationally predicted, putative hsa-miR-486-3p targets. Among them, we selected c-maf transcript as upregulated upon myb silencing. Worth of note, c-maf silencing in CD34+ progenitor cells was able to reverse the affects of myb silencing on erythroid versus megakaryocyte lineage choice. Integrative miRNA/mRNA analysis highlighted a set of miRNAs and anticorrelated putative target mRNAs modulated upon myb silencing, therefore potential players in myb-driven HPCs lineage choice. Among them, we demonstrated the hsa-miR-486-3p/c-maf pair as partially contributing to the effects of myb on HPCs commitment. Therefore, our data collectively identified myb-driven hsa-miR-486-3p upregulation and subsequent c-maf downregulation as a new molecular mechanism through which cMyb favours erythropoiesis while restraining megakaryopoiesis. Gene expression profile (GEP) was performed on total RNA derived from three independent experiments at 24h after the last nucleofection.
Project description:Defects in stress responses are important contributors in many chronic conditions including cancer, cardiovascular disease, diabetes, and obesity-driven pathologies like non-alcoholic steatohepatitis (NASH). Specifically, endoplasmic reticulum (ER) stress is linked with these pathologies and control of ER stress can ameliorate tissue damage. MicroRNAs have a critical role in regulating diverse stress responses including ER stress. Here we show that miR-494-3p plays a functional role during ER stress. ER stress inducers (tunicamycin and thapsigargin) robustly increase the expression of miR-494 in vitro in an ATF6 dependent manner. Surprisingly, miR-494 pretreatment dampens the induction and magnitude of ER stress in response to tunicamycin in endothelial cells. Conversely, inhibition of miR-494 increases ER stress de novo and amplifies the effects of ER stress inducers. Using Mass Spectrometry (TMT-MS) we identified many proteins that are downregulated by both tunicamycin and miR-494 in cultured human umbilical vein endothelial cells (HUVECs). Among these, we found 6 transcripts which harbor a putative miR-494 binding site. Our data indicates that ER stress driven miR-494 may act in a feedback inhibitory loop to dampen downstream ER stress signaling. We propose that RNA-based approaches targeting miR-494 or its targets may be attractive candidates for inhibiting ER stress dependent pathologies in human disease.