Neural Crest-Specific and General Expression of Distinct Metalloprotease–Disintegrins in EarlyXenopus laevisDevelopment

Abstract

Metalloprotease–disintegrins are a family of membrane-anchored glycoproteins that have been implicated in diverse cellular processes, including fertilization and myoblast fusion, release of TNFα from the plasma membrane, and neurogenesis. Here we report the cloning of cDNAs encoding three full-length (xMDC9, xMDC11b, and xMDC13), and one partial (xMDC11a) metalloprotease–disintegrin from the amphibianXenopus laevis,and the analysis of their expression during earlyX. laevisdevelopment and in adult tissues. The most notable finding was the highly localized and specific expression pattern ofxmdc11aat the tailbud stage in the cranial neural crest and in a subset of neural tube cells in the trunk region. In contrast, expression of the closely relatedxmdc11bwas not detectable during the early stages ofX. laevisdevelopment, and remained low in the adult tissues examined here. Distinct expression patterns were also observed for two other highly relatedX. laevisgenes,xmdc13andadam13(Alfandariet al.,1997). Whileadam13is expressed in the somitic mesoderm and in neural crest cells, but not in adult testis,xmdc13expression is low and ubiquitous in the developing embryo, but is clearly present in adult testis. Finally,xmdc9,the putative orthologue of human and mousemdc9,was found at all stages of development, and in all tissues examined, suggesting a function that may be utilized by most or all cells. The noteworthy features of these fourxmdcgenes and the implications of their distinct spatial and temporal expression patterns are discussed.