Phenotypic characterization of miR-92a-/- mice reveals an important function of miR-92a in skeletal development.

Daniela Penzkofer,Ariane Fischer,Stefanie Dimmeler,Andreas M Zeiher,Ralf P Brandes,Alexander Tups,Angelika Bonauer,Annarosa Leri

doi:10.1371/journal.pone.0101153

Abstract

MicroRNAs (miRNAs, miRs) emerged as key regulators of gene expression. Germline hemizygous deletion of the gene that encodes the miR-17∼92 miRNA cluster was associated with microcephaly, short stature and digital abnormalities in humans. Mice deficient for the miR-17∼92 cluster phenocopy several features such as growth and skeletal development defects and exhibit impaired B cell development. However, the individual contribution of miR-17∼92 cluster members to this phenotype is unknown. Here we show that germline deletion of miR-92a in mice is not affecting heart development and does not reduce circulating or bone marrow-derived hematopoietic cells, but induces skeletal defects. MiR-92a−/− mice are born at a reduced Mendelian ratio, but surviving mice are viable and fertile. However, body weight of miR-92a−/− mice was reduced during embryonic and postnatal development and adulthood. A significantly reduced body and skull length was observed in miR-92a−/− mice compared to wild type littermates. µCT analysis revealed that the length of the 5th mesophalanx to 5th metacarpal bone of the forelimbs was significantly reduced, but bones of the hindlimbs were not altered. Bone density was not affected. These findings demonstrate that deletion of miR-92a is sufficient to induce a developmental skeletal defect.

Highlights

MicroRNAs are key regulators of gene expression by binding to target mRNAs thereby inducing RNA degradation or blocking translation
We demonstrate that genetic deletion of miR-92a does not affect heart and lung development or B cell survival, but reflects the skeletal development defects observed in full cluster knockouts
MiR-92a2/2 mice showed a moderate, but significant decrease in miR-19a, miR19b, and miR-20a in the heart, whereas only miR-19b and miR20a were significantly decreased in muscle and miR-18a was significantly reduced in skeletal tissue (Figure 1C, Figure S1A/B)

Summary

Introduction

MicroRNAs (miRNAs, miRs) are key regulators of gene expression by binding to target mRNAs thereby inducing RNA degradation or blocking translation. Deletion of the miR-17,92 cluster resulted in defects of heart and lung development, and homozygote mice postnatally died [6]. A germline hemizygous deletions of MIR17HG, encoding the miR-17,92 polycistronic miRNA cluster, was observed in patients with Feingold syndrome [7], which is an autosomal dominant syndrome whose core features are microcephaly, relative short stature and digital anomalies, brachymesophalangy of the second and fifth fingers and brachysyndactyly of the toes [8]. Several key features of this phenotype were mimicked in mice harboring targeted deletion of the miR-17,92 cluster [7]. MiR-17-92D/+ mice showed a reduced body mass, skull size and a reduced length of the 5th mesophalanx to 5th metacarpal bone [7]

Methods

Results

Conclusion