Characterization and expression of two matrix metalloproteinase genes during sea urchin development

Matrix metalloproteinases (MMPs) play an essential role in a variety of processes in development that require extracellular matrix remodeling and degradation. In this study, we characterize two MMPs from the sea urchin Strongylocentrotus purpuratus. These clones can both be identified as MMPs based on the presence of conserved domains such as the cysteine switch, zinc-binding, and hemopexin domains. In addition, both of these genes contain consensus furin cleavage sites and putative transmembrane domains, classifying them as membrane-type MMPs. We have named these clones SpMMP14 and SpMMP16 based on the vertebrate MMPs with which they share the greatest similarity. SpMMP14 is expressed in all cells from the egg to mesenchyme blastula stage embryo. Expression of this gene is strongest in the animal and vegetal poles early in gastrulation and in the animal pole only later in gastrulation. SpMMP16 is expressed at low levels in eggs. Expression of SpMMP16 becomes more pronounced in the vegetal pole region at the blastula and mesenchyme blastula stages and becomes confined to vegetal pole descendants, such as pigment cells, later in development. In the future, we hope to learn more about the possible functions of these genes in sea urchin development.