Transcriptional regulation of Mesp1 and Mesp2 genes: differential usage ofenhancers during development

Mesp1 and Mesp2 encode bHLH-type transcription factors, Mesp1 and Mesp2, re spectively. The expression of both genes is observed in the nascent mesoder m, and subsequently in the rostral presomitic mesoderm. To determine the re gulatory mechanism for gene expression, we attempted to identify enhancer e lements by transient transgenic analysis. At least two enhancers, which are responsible for the expression of the two genes in the early mesoderm (ear ly mesodermal enhancer, EME) and the presomitic mesoderm (PSM enhancer, PSM E), and one suppressor, which is responsible for the rostrally restricted e xpression in the presomitic mesoderm, were identified. Deletion studies of these enhancer elements indicate that either gene may use the same enhancer for early mesoderm development, whereas both genes may utilize separate en hancers to regulate their expression in the presomitic mesoderm. (C) 2001 E lsevier Science Ireland Ltd. All rights reserved.