MIR-23A microRNA cluster inhibits B-cell development.
OBJECTIVE
The transcription factor PU.1 (encoded by Sfpi1) promotes myeloid differentiation, but it is unclear what downstream genes are involved. Micro RNAs (miRNAs) are a class of small RNAs that regulate many cellular pathways, including proliferation, survival, and differentiation. The objective of this study was to identify miRNAs downstream of PU.1 that regulate hematopoietic development.


METHODS
miRNAs that change expression in a PU.1-inducible cell line were identified with microarrays. The promoter for an miRNA cluster upregulated by PU.1 induction was analyzed for PU.1 binding by electrophoretic mobility shift and chromatin immunoprecipitation assays. Retroviral transduction of hematopoietic progenitors was performed to evaluate the effect of miRNA expression on hematopoietic development in vitro and in vivo.


RESULTS
We identified an miRNA cluster whose pri-transcript is regulated by PU.1. The pri-miRNA encodes three mature miRNAs: miR-23a, miR-27a, and miR-24-2. Each miRNA is more abundant in myeloid cells compared to lymphoid cells. When hematopoietic progenitors expressing the 23a cluster miRNAs were cultured in B-cell-promoting conditions, we observed a dramatic decrease in B lymphopoiesis and an increase in myelopoiesis compared to control cultures. In vivo, hematopoietic progenitors expressing the miR-23a cluster generate reduced numbers of B cells compared to control cells.


CONCLUSIONS
The miR-23a cluster is a downstream target of PU.1 involved in antagonizing lymphoid cell fate acquisition. Although miRNAs have been identified downstream of PU.1 in mediating development of monocytes and granulocytes, the 23a cluster is the first downstream miRNA target implicated in regulating development of myeloid vs lymphoid cells.
Kong
Kimi Y
KY
Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM.
Owens
Kristin S
KS
Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM.
Rogers
Jason H
JH
Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM.
Mullenix
Jason
J
Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM.
Velu
Chinavenmeni S
CS
Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.
Grimes
H Leighton
HL
Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.
Dahl
Richard
R
Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM.|Department of Internal Medicine, Health Sciences Center, University of New Mexico, Albuquerque, NM.
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D005786:Gene Expression Regulation / Q000502:physiology*; D006412:Hematopoietic Stem Cells; D038041:Lymphopoiesis / Q000502:physiology*; D051379:Mice; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D022423:Myeloid Cells / Q000166:cytology / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D000099232:Proto-Oncogene Protein Spi-1
D035683:MicroRNAs; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C534062:Mirn23b microRNA, mouse; C529080:Mirn24 microRNA, mouse; C540674:Mirn27 microRNA, mouse
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