Project description:To identify the effects of hypoxia on stem cell populations, we subjected human mesenchymal stem cells to a pO2 of 4 mmHg and analyzed global gene expression and alternative splicing (AS) by genome-exon microarray. Hypoxia induced gene expression in human mesenchymal stem cells was measured at 24 hours after exposure to 0.5% oxygen or normal 21% oxygen. Three independent experiments were performed per condition (Hypoxia or Normoxia).
Project description:miRNA microarray expression analysis of Human Bone Marrow Stem Cells from healthy (BM) and end-stage critical limb ischemia (CLI) patients (PZ) in normal and hypoxic conditions
Project description:DEAD-box RNA-binding proteins (RBPs) play a significant role in RNA metabolism to achieve cellular homeostasis, including miRNA biogenesis and transcription. Hypoxia induces stemness cell-like characteristics in cancer cells and promotes malignant progression. Despite the fact that hypoxia can induce the changes in protein and RNA modification, thereby regulating downstream gene expressions, how modifications at different molecular layers interplay with each other are poorly understood. Here we show that hypoxia induces HectH9-mediated K63-linked polyubiquitination of the DEAD-box protein DDX17 as well as reduces N6-methyladenosine (m6A) marks in pri-miRNAs. While m6A potentiates DDX17 binding to pri-miRNAs, decreased m6A modifications of pri-miRNAs and increased polyubiquitination of DDX17 under hypoxia lead to decreased DDX17 binding to pri-miRNAs binding. These events enhance the association of DDX17 with the ubiquitin receptor p300 and lead to a decrease in miRNA biogenesis, especially for miRNAs regulating stemness and stemness-related genes. In addition, polyubiquitinated DDX17 together with p300 upregulates H3K56Ac levels on the stemness and stemness-related genes, resulting in enhancement of tumor initiating ability. Post-transcriptionally, decreased miRNA production, including those targeting stemness genes or stemness-related genes, also facilitates tumor initiation. Together, hypoxia triggers DDX17 poly-ubiquitination, which orchestrates dual mechanisms to increase tumor initiating ability and promote tumor progression.
Project description:Human mesenchymal/stromal stem cells (hMSC) are the most promising cell source for adult cell therapies in regenerative medicine. Many clinical trials have reported the use of autologous transplantation of hMSCs in several disorders, but with limited results. To exert their potential, hMSCs could exhibit efficient homing and migration toward lesion sites among other effects, but the underlying process is not clear enough. To further increase the knowledge, we studied the co-regulation between hypoxia-regulated genes and miRNAs. To this end, we investigated the miRNA expression profile of healthy hMSCs in low oxygen/nutrient conditions to mimic ischemia and compared with cells of patients suffering from critical limb ischemia (CLI). miRNAs are small, highly conserved, non-coding RNAs, skilled in the control of the target's expression level in a fine-tuned way. After analyzing the miRNOme in CLI-derived hMSC cells and healthy controls, and intersecting the results with the mRNA expression dataset under hypoxic conditions, we identified two miRNAs potentially relevant to the disease: miR-29b as a pathological marker of the disease and miR-638 as a therapeutic target. This study yielded a deeper understanding of stem cell biology and ischemic disorders, opening new potential treatments in the future.
Project description:To identify the effects of hypoxia on stem cell populations, we subjected human mesenchymal stem cells to a pO2 of 4 mmHg and analyzed global gene expression and alternative splicing (AS) by genome-exon microarray.
Project description:Differentiation of mesenchymal stem cells relies on precise control of tightly controlled genetic programme where specific sets of genes are up-regulated. Identification of miRNAs that are modulated during this process should help to better understand cho
Project description:Human adipose-derived mesenchymal stem cells were cultured either in hypoxia (Hx; <0.1% oxygen) or standard culture conditions (normoxia, Nx) over 48 hours in serum-free medium. Human tympanic membrane keratinocytes were cultured in standard culture conditions over 48 hours in serum-free medium.
Project description:To determine whether hypoxia augments the activity of exosomes by modulating miRNAs, we use miRNA array profile to find the differential expression of miRNAs of exosomes in different culture conditions (normoxia, hypoxia, hypoxia supplemented with GW4869 which is an inhibitor of exosomes generation).