Analysis of CMF1 reveals a bone morphogenetic protein-independent component of the cardiomyogenic pathway

Disruption of the CMF1 function in anterior mesoderm inhibits cardiac myogenesis in avian embryos. In the present study, we show that CMF1 is a member of an emerging family of proteins that includes centromeric protein-F, mitosin, and LEK1. These proteins are characterized by their large size (350 kDa), dynamic subcellular distribution, and potential functions in cell division and differentiation. The current data suggest that CMF1 is a unique member of this family by virtue of its restricted protein expression and variant subcellular distribution. Immunochemical analysis demonstrates that CMF1 protein is expressed in cardiogenic cells prior to the activation of cardiac structural gene products. In addition, we show that expression of CMF1 is not dependent on the bone morphogenetic protein (BMP) signaling pathway during development. Still, CMF1 cannot direct cardiomyogenesis in the absence of such factors as NKX-2.5. Taken with our previous data, this study suggests that CMF1 is a BMP-independent component of the cardiomyogenic pathway.