Expression of meltrin-alpha mRNA is not restricted to fusagenic cells

Meltrin-alpha is a myoblast gene product reported to be required for cell fusion [Yagami-Hiromasa et al. (1995): Nature 377:652-656]. Because Northern blots revealed expression only in muscle and bone, the suggestion was made that meltrin-alpha is expressed exclusively by fusagenic cells in these tissues (myoblast and osteoclast). We studied expression of meltrin-alpha mRNA in a panel of tissues and cell lines using the polymerase chain reaction and found it widely expressed. Meltrin-alpha mRNA was readily detected in the osteoblast, the most abundant cell type in bone. In situ hybridization analysis on sections of neonatal mice revealed high levels of expression in the trabecular meshwork of long bones, the basal regions of the dermis and its underlying mesenchyme. We conclude that expression of meltrin-alpha mRNA is not restricted to fusagenic cells and that, in bone, the osteoblast is the major source.