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Proc Natl Acad Sci U S A. 2015 Sep 1;112(35):E4884-93. doi: 10.1073/pnas.1512655112. Epub 2015 Aug 17.

Independent regulation of vertebral number and vertebral identity by microRNA-196 paralogs.

Author information

1
EMBL Australia, Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia;
2
Howard Hughes Medical Institute, Cambridge, MA 02142; Whitehead Institute for Biomedical Research, Cambridge, MA 02142; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139; Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA 02139;
3
Department of Genetics, Harvard Medical School, Boston, MA 02115; Department of Biological Sciences, Barnard College, New York, NY 10027;
4
Department of Developmental Biology and Genetics, Stanford School of Medicine, Stanford, CA 94305;
5
Department of Genetics, Harvard Medical School, Boston, MA 02115;
6
The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom;
7
Department of Genetics, Harvard Medical School, Boston, MA 02115; Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115.
8
Howard Hughes Medical Institute, Cambridge, MA 02142; Whitehead Institute for Biomedical Research, Cambridge, MA 02142; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139;
9
Department of Genetics, Harvard Medical School, Boston, MA 02115; tabin@genetics.med.harvard.edu edwina.mcglinn@emblaustralia.org.
10
EMBL Australia, Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia; Department of Genetics, Harvard Medical School, Boston, MA 02115; tabin@genetics.med.harvard.edu edwina.mcglinn@emblaustralia.org.

Abstract

The Hox genes play a central role in patterning the embryonic anterior-to-posterior axis. An important function of Hox activity in vertebrates is the specification of different vertebral morphologies, with an additional role in axis elongation emerging. The miR-196 family of microRNAs (miRNAs) are predicted to extensively target Hox 3' UTRs, although the full extent to which miR-196 regulates Hox expression dynamics and influences mammalian development remains to be elucidated. Here we used an extensive allelic series of mouse knockouts to show that the miR-196 family of miRNAs is essential both for properly patterning vertebral identity at different axial levels and for modulating the total number of vertebrae. All three miR-196 paralogs, 196a1, 196a2, and 196b, act redundantly to pattern the midthoracic region, whereas 196a2 and 196b have an additive role in controlling the number of rib-bearing vertebra and positioning of the sacrum. Independent of this, 196a1, 196a2, and 196b act redundantly to constrain total vertebral number. Loss of miR-196 leads to a collective up-regulation of numerous trunk Hox target genes with a concomitant delay in activation of caudal Hox genes, which are proposed to signal the end of axis extension. Additionally, we identified altered molecular signatures associated with the Wnt, Fgf, and Notch/segmentation pathways and demonstrate that miR-196 has the potential to regulate Wnt activity by multiple mechanisms. By feeding into, and thereby integrating, multiple genetic networks controlling vertebral number and identity, miR-196 is a critical player defining axial formulae.

KEYWORDS:

Hox genes; axial patterning; miR-196; microRNA; vertebral specification

PMID:
26283362
PMCID:
PMC4568285
DOI:
10.1073/pnas.1512655112
[Indexed for MEDLINE]
Free PMC Article

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