Spatially- and temporally-restricted expression of meltrin α (ADAM12) and β (ADAM19) in mouse embryo

The cloning of the full-length cDNA encoding meltrin β (ADAM19), one of the metalloprotease-disintegrins expressed in mouse myogenic cells, revealed that the meltrin β gene encodes a membrane protein closely related to meltrin α (ADAM12) which participates in myotube formation in vitro. To delineate the functions of meltrin α and β, we examined the expression patterns of their transcripts during embryogenesis. The meltrin α gene is activated in condensed mesenchymal cells that give rise to skeletal muscle, bones and visceral organs. Meltrin β mRNA, in contrast, is markedly expressed in craniofacial and dorsal root ganglia and ventral horns of the spinal cord, where peripheral neuronal cell lineages differentiate. Heart, skeletal muscle, intestine and lung also express meltrin β mRNA transiently. Although the meltrin α and β transcripts exhibit distinct expression patterns during embryogenesis, both genes are mainly activated in mesenchymal cells that are derived from both mesoderm and ectoderm.