title: Genetic screen identifies microRNA cluster 99b/let-7e/125a as a regulator of primitive hematopoietic cells.
abstract: Hematopoietic stem/progenitor cell (HSPC) traits differ between genetically distinct mouse strains. For example, DBA/2 mice have a higher HSPC frequency compared with C57BL/6 mice. We performed a genetic screen for micro-RNAs that are differentially expressed between LSK, LS(-)K(+), erythroid and myeloid cells isolated from C57BL/6 and DBA/2 mice. This analysis identified 131 micro-RNAs that were differentially expressed between cell types and 15 that were differentially expressed between mouse strains. Of special interest was an evolutionary conserved miR cluster located on chromosome 17 consisting of miR-99b, let-7e, and miR-125a. All cluster members were most highly expressed in LSKs and down-regulated upon differentiation. In addition, these microRNAs were higher expressed in DBA/2 cells compared with C57BL/6 cells, and thus correlated with HSPC frequency. To functionally characterize these microRNAs, we overexpressed the entire miR-cluster 99b/let-7e/125a and miR-125a alone in BM cells from C57BL/6 mice. Overexpression of the miR-cluster or miR-125a dramatically increased day-35 CAFC activity and caused severe hematopoietic phenotypes upon transplantation. We showed that a single member of the miR-cluster, namely miR-125a, is responsible for the majority of the observed miR-cluster overexpression effects. Finally, we performed genome-wide gene expression arrays and identified candidate target genes through which miR-125a may modulate HSPC fate.
authors: Department of Cell Biology, Section Stem Cell Biology, University Medical Center Groningen, University of Groningen, The Netherlands.
authors: Alice
authors: A
authors: Gerrits
authors: Marta A
authors: MA
authors: Walasek
authors: Sandra
authors: S
authors: Olthof
authors: Ellen
authors: E
authors: Weersing
authors: Martha
authors: M
authors: Ritsema
authors: Erik
authors: E
authors: Zwart
authors: Ronald
authors: R
authors: van Os
authors: Leonid V
authors: LV
authors: Bystrykh
authors: Gerald
authors: G
authors: de Haan
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002478:Cells, Cultured; D041905:Erythroid Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D035683:MicroRNAs / Q000235:genetics*; D022423:Myeloid Cells / Q000166:cytology / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; C531888:MIRN125 microRNA, human; C561679:MIRN99 microRNA, human; D035683:MicroRNAs; C487931:mirnlet7 microRNA, human