Elsevier

Developmental Biology

Volume 413, Issue 2, 15 May 2016, Pages 160-172
Developmental Biology

Osterix/Sp7 limits cranial bone initiation sites and is required for formation of sutures

https://doi.org/10.1016/j.ydbio.2016.03.011Get rights and content
Under a Creative Commons license
open access

Highlights

  • Zebrafish lacking Sp7 make bone, consistent with the human mutant phenotype.

  • Global gene expression correlates with delayed osteogenesis and poor mineralization.

  • The mutant skull has specific defects in shape and bones of the cranial vault.

  • Signaling from mature bone limits osteoblast recruitment during skull growth.

Abstract

During growth, individual skull bones overlap at sutures, where osteoblast differentiation and bone deposition occur. Mutations causing skull malformations have revealed some required genes, but many aspects of suture regulation remain poorly understood. We describe a zebrafish mutation in osterix/sp7, which causes a generalized delay in osteoblast maturation. While most of the skeleton is patterned normally, mutants have specific defects in the anterior skull and upper jaw, and the top of the skull comprises a random mosaic of bones derived from individual initiation sites. Osteoblasts at the edges of the bones are highly proliferative and fail to differentiate, consistent with global changes in gene expression. We propose that signals from the bone itself are required for orderly recruitment of precursor cells and growth along the edges. The delay in bone maturation caused by loss of Sp7 leads to unregulated bone formation, revealing a new mechanism for patterning the skull and sutures.

Keywords

Osterix/Sp7
Craniofacial skeleton
Sutures
Osteogenesis
Zebrafish mutant

Cited by (0)

1

Current address: Department of Genetics and Evolutionary Biology, University of São Paulo, SP, Brazil.

2

Current address: Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA.

3

Current address: Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA.