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Haematologica 2019 Volume 104(9):1744-1755
Hematopoiesis
MicroRNA-127-3p controls murine hematopoietic stem cell maintenance by limiting differentiation
Laura Crisafulli,1,2 Sharon Muggeo,1,2 Paolo Uva,3 Yulei Wang,4
Masayuki Iwasaki,5 Silvia Locatelli,6 Achille Anselmo,7 Federico S. Colombo,7 Carmelo Carlo-Stella,6,8 Michael L. Cleary,5 Anna Villa,1,9 Bernhard Gentner9 and Francesca Ficara1,2
1UOS Milan Unit, Istituto di Ricerca Genetica e Biomedica (IRGB), CNR, Milan, Italy;
2Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy; 3CRS4, Science and
4
Technology Park Polaris, Pula, Cagliari, Italy; Genentech Inc., South San Francisco, CA,
USA; 5Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA; 6Department of Oncology and Hematology, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy; 7Flow Cytometry Core, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy; 8Humanitas Huniversity, Department of Biomedical Sciences, Pieve Emanuele, Milan, Italy and 9San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), IRCCS San Raffaele Scientific Institute, Milan, Italy
ABSTRACT
The balance between self-renewal and differentiation is crucial to ensure the homeostasis of the hematopoietic system, and is a hall- mark of hematopoietic stem cells. However, the underlying molec- ular pathways, including the role of micro-RNA, are not completely under- stood. To assess the contribution of micro-RNA, we performed micro- RNA profiling of hematopoietic stem cells and their immediate down- stream progeny multi-potent progenitors from wild-type control and Pbx1-conditional knockout mice, whose stem cells display a profound self- renewal defect. Unsupervised hierarchical cluster analysis separated stem cells from multi-potent progenitors, suggesting that micro-RNA might reg- ulate the first transition step in the adult hematopoietic development. Notably, Pbx1-deficient and wild-type cells clustered separately, linking micro-RNAs to self-renewal impairment. Differential expression analysis of micro-RNA in the physiological stem cell-to-multi-potent progenitor transition and in Pbx1-deficient stem cells compared to control stem cells revealed miR-127-3p as the most differentially expressed. Furthermore, miR-127-3p was strongly stem cell-specific, being quickly down-regulated upon differentiation and not re-expressed further downstream in the bone marrow hematopoietic hierarchy. Inhibition of miR-127-3p function in Lineage-negative cells, achieved through a lentiviral-sponge vector, led to severe stem cell depletion, as assessed with serial transplantation assays. miR-127-3p-sponged stem cells displayed accelerated differentiation, which was uncoupled from proliferation, accounting for the observed stem cell reduction. miR-127-3p overexpression in Lineage-negative cells did not alter stem cell pool size, but gave rise to lymphopenia, likely due to lack of miR-127-3p physiological downregulation beyond the stem cell stage. Thus, tight regulation of miR-127-3p is crucial to preserve the self- renewing stem cell pool and homeostasis of the hematopoietic system.
Introduction
Hematopoietic stem cells (HSC) are characterized by their ability to give rise to all blood lineages for the entire lifespan of an individual. In order to preserve this capability throughout life, a reservoir of quiescent stem cells is maintained in the bone marrow (BM) microenvironment.1 This occurs through transcriptional and epigenetic mechanisms that actively repress cell cycling, differentiation, apoptosis, and senescence, or protect from oxidative stress. To generate the progenitors that
Correspondence:
FANCESCA FICARA
francesca.ficara@humanitasresearch.it
Received: May 24, 2018. Accepted: February 14, 2019. Pre-published: February 21, 2019.
doi:10.3324/haematol.2018.198499
Check the online version for the most updated information on this article, online supplements, and information on authorship & disclosures: www.haematologica.org/content/104/9/1744
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