Meeting Abstract
The avian appendicular skeleton arises from a cartilage template that is in turn prefigured by aggregations of mesenchymal cells (known as condensations) within the limb bud. The pattern that determines where condensation form, and how they are spaced apart is generated by a pair of endogenously expressed lectins, Galectin-1A and -8 and their glycoconjugate receptors. Galectin-1A (Gal-1A) is responsible for cell adhesion that leads to condensation formation whereas Gal-8 inhibits the same. Their positive regulation of each other’s gene expression and opposite effect on cell aggregation has led us to construct a reaction-diffusion-adhesion model for limb patterning. What remains unclear is how this local mechanism is spatially synchronized across the morphogenetic field, i.e., the high density micromass in vitro and the digital plate in vivo. I will discuss new experimental observations that implicate the role of oscillatory expression of Notch signaling in the global entrainment of condensation formation. Integrating these findings within our theoretical framework allows us to predict the effects of Notch signaling on the pattern formation and differentiation of limb precartilage mesenchymal cells.
