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Molecular and Cellular Biology, May 2009, p. 2762-2776, Vol. 29, No. 10
0270-7306/09/$08.00+0 doi:10.1128/MCB.01393-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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Stavros Milatos,1,
Anthie Yiakouvaki,1
Nikos Sgantzis,1
Anastasia Kotsoni,1
Maria Alexiou,1
Vaggelis Harokopos,1
Vassilis Aidinis,1
Myriam Hemberger,2 and
Dimitris L. Kontoyiannis1*
Institute of Immunology, Biomedical Sciences Research Center Alexander Fleming, 16672 Vari, Greece,1 Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom2
Received 5 September 2008/ Returned for modification 20 October 2008/ Accepted 10 March 2009
HuR is an RNA-binding protein implicated in a diverse array of pathophysiological processes due to its effects on the posttranscriptional regulation of AU- and U-rich mRNAs. Here we reveal HuR's requirement in embryonic development through its genetic ablation. Obligatory HuR-null embryos exhibited a stage retardation phenotype and failed to survive beyond midgestation. By means of conditional transgenesis, we restricted HuR's mutation in either embryonic or endothelial compartments to demonstrate that embryonic lethality is consequent to defects in extraembryonic placenta. HuR's absence impaired the invagination of allantoic capillaries into the chorionic trophoblast layer and the differentiation of syncytiotrophoblast cells that control the morphogenesis and vascularization of the placental labyrinth and fetal support. HuR-null embryos rescued from these placental defects proceeded to subsequent developmental stages but displayed defects in skeletal ossification, fusions in limb elements, and asplenia. By coupling gene expression measurements, data meta-analysis, and HuR-RNA association assays, we identified transcription and growth factor mRNAs controlled by HuR, primarily at the posttranscriptional level, to guide morphogenesis, specification, and patterning. Collectively, our data demonstrate the dominant role of HuR in organizing gene expression programs guiding placental labyrinth morphogenesis, skeletal specification patterns, and splenic ontogeny.
Published ahead of print on 23 March 2009.
Supplemental material for this article may be found at http://mcb.asm.org/.
These authors contributed equally.
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