English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The skeleton is one of the most important features for the reconstruction of vertebrate phylogeny but few data are available to understand its molecular origin. In mammals the  Runt  genes are central regulators of skeletogenesis.  Runx2  was shown to be essential for osteoblast differentiation, tooth development, and bone formation. Both  Runx2  and  Runx3  are essential for chondrocyte maturation. Furthermore,  Runx2  directly regulates  Indian hedgehog  expression, a master coordinator of skeletal development. To clarify the correlation of  Runt  gene evolution and the emergence of cartilage and bone in vertebrates, we cloned the  Runt  genes from hagfish as representative of jawless fish ( MgRunxA ,  MgRunxB ) and from dogfish as representative of jawed cartilaginous fish ( ScRunx1–3 ). According to our phylogenetic reconstruction the stem species of chordates harboured a single  Runt  gene and thereafter  Runt  locus duplications occurred during early vertebrate evolution. All newly isolated  Runt  genes were expressed in cartilage according to quantitative PCR. In situ hybridisation confirmed high  MgRunxA  expression in hard cartilage of hagfish. In dogfish  ScRunx2  and  ScRunx3  were expressed in embryonal cartilage whereas all three  Runt  genes were detected in teeth and placoid scales. In cephalochordates (lancelets)  Runt ,  Hedgehog  and  SoxE  were strongly expressed in the gill bars and expression of  Runt  and  Hedgehog  was found in endo- as well as ectodermal cells. Furthermore we demonstrate that the lancelet Runt protein binds to  Runt  binding sites in the lancelet  Hedgehog  promoter and regulates its activity. Together, these results suggest that  Runt  and  Hedgehog  were part of a core gene network for cartilage formation, which was already active in the gill bars of the common ancestor of cephalochordates and vertebrates and diversified after  Runt  duplications had occurred during vertebrate evolution. The similarities in expression patterns of  Runt  genes support the view that teeth and placoid scales evolved from a homologous developmental module.

Evolution of a Core Gene Network for Skeletogenesis in Chordates