Polycombs and microRNA-223 regulate human granulopoiesis by transcriptional control of target gene expression.
Epigenetic modifications regulate developmental genes involved in stem cell identity and lineage choice. NFI-A is a posttranscriptional microRNA-223 (miR-223) target directing human hematopoietic progenitor lineage decision: NFI-A induction or silencing boosts erythropoiesis or granulopoiesis, respectively. Here we show that NFI-A promoter silencing, which allows granulopoiesis, is guaranteed by epigenetic events, including the resolution of opposing chromatin "bivalent domains," hypermethylation, recruitment of polycomb (PcG)-RNAi complexes, and miR-223 promoter targeting activity. During granulopoiesis, miR-223 localizes inside the nucleus and targets the NFI-A promoter region containing PcGs binding sites and miR-223 complementary DNA sequences, evolutionarily conserved in mammalians. Remarkably, both the integrity of the PcGs-RNAi complex and DNA sequences matching the seed region of miR-223 are required to induce NFI-A transcriptional silencing. Moreover, ectopic miR-223 expression in human myeloid progenitors causes heterochromatic repression of NFI-A gene and channels granulopoiesis, whereas its stable knockdown produces the opposite effects. Our findings indicate that, besides the regulation of translation of mRNA targets, endogenous miRs can affect gene expression at the transcriptional level, functioning in a critical interface between chromatin remodeling complexes and the genome to direct fate lineage determination of hematopoietic progenitors.
San Raffaele Bio-medical Park Foundation, Rome, Italy. zardo@bce.uniroma1.it
Giuseppe
G
Zardo
Alberto
A
Ciolfi
Laura
L
Vian
Linda M
LM
Starnes
Monia
M
Billi
Serena
S
Racanicchi
Carmen
C
Maresca
Francesco
F
Fazi
Lorena
L
Travaglini
Nelida
N
Noguera
Marco
M
Mancini
Mauro
M
Nanni
Giuseppe
G
Cimino
Francesco
F
Lo-Coco
Francesco
F
Grignani
Clara
C
Nervi
D001483:Base Sequence; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D057890:Epigenomics; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006098:Granulocytes / Q000166:cytology*; D006410:Hematopoiesis / Q000502:physiology; D006570:Heterochromatin / Q000235:genetics; D006801:Humans; D047468:Immunoprecipitation; D007938:Leukemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008156:Luciferases / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D038042:Myelopoiesis / Q000502:physiology; D051839:NFI Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D063146:Polycomb-Group Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012097:Repressor Proteins / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D006570:Heterochromatin; D008156:Luciferases; D035683:MicroRNAs; D051839:NFI Transcription Factors; D063146:Polycomb-Group Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012097:Repressor Proteins; C525067:MIR223, human; C497592:NFIA protein, human