MicroRNA-130a-mediated down-regulation of Smad4 contributes to reduced sensitivity to TGF-β1 stimulation in granulocytic precursors.
Smad4 is important in the TGF-β pathway and required for transcriptional activation and inhibition of cell growth after TGF-β1 stimulation. We demonstrate that miR-130a is differentially expressed during granulopoiesis and targets Smad4 mRNA. The transcript for Smad4 is present throughout neutrophil maturation, but Smad4 protein is undetectable in the most immature cells, where miR-130a is highly expressed. Two miR-130a binding sites were identified in the 3'-untranslated region of the Smad4 mRNA. Overexpression of miR-130a in HEK293, A549, and 32Dcl3 cells repressed synthesis of Smad4 protein without affecting Smad4 mRNA level. Repression of Smad4 synthesis in a granulocytic cell line by miR-130a reduced its sensitivity to TGF-β1-induced growth inhibition. This effect was reversed by inhibiting the activity of miR-130a with an antisense probe or by expressing a Smad4 mRNA lacking miR-130a binding sites. High endogenous miR-130a and Smad4 mRNA levels and low expression of Smad4 protein were found in the t(8;21)(q22;q22) acute myelogenous leukemia-derived cell line Kasumi-1. When miR-130a was inhibited by an antisense RNA, the amount of Smad4 protein increased in Kasumi-1 cells and rendered it susceptible for TGF-β1-mediated cell growth inhibition. Our data indicate that miR-130a is involved in cell cycle regulation of granulocytic cells through engagement of Smad4 in the TGF-β pathway.
Granulocyte Research Laboratory, Department of Haematology, Rigshospitalet, Blegdamsvej 9, Copenhagen, Denmark
Mattias
M
Häger
Corinna Cavan
CC
Pedersen
Maria Torp
MT
Larsen
Mette Klarskov
MK
Andersen
Christoffer
C
Hother
Kirsten
K
Grønbæk
Hanne
H
Jarmer
Niels
N
Borregaard
Jack Bernard
JB
Cowland
D020413:3' Untranslated Regions / Q000235:genetics; D000208:Acute Disease; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D042381:Granulocyte Precursor Cells / Q000187:drug effects* / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051901:Smad4 Protein / Q000235:genetics* / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
D020413:3' Untranslated Regions; C554019:MIRN130 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D053773:Transforming Growth Factor beta1