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Mesenchymal stromal cells (MSC) may exert their functions by the release of extracellular vesicles (EV). Our aim was to analyze changes induced in CD34 + cells after the incorporation of MSC-EV. MSC-EV were characterized by flow cytometry (FC), Western blot, electron microscopy, and nanoparticle tracking analysis. EV incorporation into CD34 + cells was confirmed by FC and confocal microscopy, and then reverse transcription polymerase chain reaction and arrays were performed in modified CD34 + cells. Apoptosis and cell cycle were also evaluated by FC, phosphorylation of signal activator of transcription 5 (STAT5) by WES Simple, and clonal growth by clonogenic assays. Human engraftment was analyzed 4 weeks after CD34 + cell transplantation in nonobese diabetic/severe combined immunodeficient mice. Our results showed that MSC-EV incorporation induced a downregulation of proapoptotic genes, an overexpression of genes involved in colony formation, and an activation of the Janus kinase (JAK)-STAT pathway in CD34 + cells. A significant decrease in apoptosis and an increased CD44 expression were confirmed by FC, and increased levels of phospho-STAT5 were confirmed by WES Simple in CD34 + cells with MSC-EV. In addition, these cells displayed a higher colony-forming unit granulocyte/macrophage clonogenic potential. Finally, the in vivo bone marrow lodging ability of human CD34 + cells with MSC-EV was significantly increased in the injected femurs. In summary, the incorporation of MSC-EV induces genomic and functional changes in CD34 + cells, increasing their clonogenic capacity and their bone marrow lodging ability. Stem Cells 2019;37:1357-1368., (©2019 The Authors. Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press 2019.)

Gene expression is generally regulated by recruitment of transcription factors and RNA polymerase II (RNAP II) to specific sequences in the gene promoter region. The Integrator complex mediates processing of small nuclear RNAs (snRNAs) as well as the initiation and release of paused RNAP II at specific genes in response to growth factors. Here we show that in C. elegans, disruption of the Integrator complex leads to transcription of genes located downstream of the snRNA loci via a non-conventional transcription mechanism based on the lack of processing of the snRNAs. RNAP II read-through generates long chimeric RNAs containing snRNA, the intergenic region and the mature mRNA of the downstream gene located in sense. These chimeric sn-mRNAs remain as untranslated long non-coding RNAs, in the case of U1- and U2-derived sn-mRNAs, but can be translated to proteins in the case of SL-derived sn-mRNAs. The transcriptional effect caused by disruption of the Integrator complex is not restricted to genes located downstream of the snRNA loci but also affects key regulators of signal transduction such as kinases and phosphatases. Our findings highlight that these transcriptional alterations may be behind the correlation between mutations in the Integrator complex and tumor transformation., Competing Interests: The authors have declared that no competing interests exist.

Small GTPases in the Rho family act as major nodes with functions beyond cytoskeletal rearrangements shaping the Caenorhabditis elegans embryo during development. These small GTPases are key signal transducers that integrate diverse developmental signals to produce a coordinated response in the cell. In C. elegans, the best studied members of these highly conserved Rho family small GTPases, RHO-1/RhoA, CED-10/Rac, and CDC-42, are crucial in several cellular processes dealing with cytoskeletal reorganization. In this review, we update the functions described for the Rho family small GTPases in spindle orientation and cell division, engulfment, and cellular movements during C. elegans embryogenesis, focusing on the Rho subfamily Rac. Please also see the video abstract here., (© 2016 The Authors BioEssays Published by WILEY Periodicals, Inc.)