A 5.5-kb Enhancer Is both Necessary and Sufficient for Regulation of Wnt-1Transcription in Vivo

Abstract

Wnt-1 encodes a secreted signaling molecule which is required for development of the midbrain and anterior hindbrain in the mouse. Wnt-1expression is initiated early in the development of the central nervous system in a region predicted to give rise to the midbrain. Later in development Wnt-1 expression is restricted to regions of the forebrain, midbrain, and spinal cord. Previous studies identified a 5.5-kb enhancer in the Wnt-1 locus which is sufficient to activate transcription of a reporter gene in a pattern very similar to that of the endogenous Wnt-1 gene. Here we have assessed if this enhancer is an important component of the endogenous regulatory sequences of Wnt-1 by gene targeting and by testing if it is able to express Wnt-1 in a pattern which is sufficient to rescue the phenotype of loss of Wnt-1. Our results show that the 5.5-kb enhancer is both necessary and sufficient for Wnt-1expression in vivo.

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