Research ArticleDevelopment

The Balance of WNT and FGF Signaling Influences Mesenchymal Stem Cell Fate During Skeletal Development

Science Signaling  25 May 2010:
Vol. 3, Issue 123, pp. ra40
DOI: 10.1126/scisignal.2000727

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A Delicate Balance in Skull Development

When skull bones initially form, they are separated by sites called sutures, and, in humans, the skull bones fuse after birth. Skull bone growth occurs through a process called intramembranous ossification, in which mesenchymal cells differentiate directly into bone-forming osteoblasts that deposit the bone matrix. Maruyama et al. found that, in mice, one layer of the posterior frontal suture closed through a process called endochondral ossification in which skeletal precursors differentiate into cartilage cells called chondrocytes before bone matrix deposition. Furthermore, they found that, when β-catenin signaling was increased and fibroblast growth factor signaling was simultaneously reduced, aberrant closure of another suture occurred through a process involving chondrogenesis. Their data suggest that, in addition to excessive osteoblastogenesis, aberrant chondrogenesis may be a mechanism by which premature closure of the skull bones, causing the disorder craniosynostosis, can occur.