An interferon regulatory factor-like binding element restricts Xmyf-5 expression in the posterior somites during Xenopus myogenesis

The expression of myf-5, a key component of myogenic regulatory genus, declines progressively in mature somitic cells during, vertebrate myogenesis. Little is known about how this down-regulation takes place. Here we provide evidence that an interferon regulatory factor binding element (IRF element) within the Xenopus myf-5 promoter is responsible for the elimination of myf-5 transcription in mature somitic mesoderm of Xenopus embryos. We show that this IRF element mediates the down-regulation of Xmyf-5 transcription in gastrula embryos, and can specifically interact with nuclear proteins of early neurula. Moreover, deletion of this IRF element results in the anterior expansion of reporter gene transcripts within somitic mesoderm in transgenic embryos. Our results, therefore, provide insight into how the negative control of Xmyf-5 expression takes place. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.